Buying a Jetjoe turbine

[jet-mad]

Help please,
I just want to buy a Jetjoe turbine kit. I've tried their web site with no luck. They didn't answer. Please could anyone that bought from these guys, tell me how to do it? Any details, most grateful. Thanks. Richard.

[HobbyCNC]

Help please,
I just want to buy a Jetjoe turbine kit. I've tried their web site with no luck. They didn't answer. Please could anyone that bought from these guys, tell me how to do it? Any details, most grateful. Thanks. Richard.

For a few bucks more I'd get a Wren 54MK3 kit and have a quality turbine.

Dave

[jet-mad]

Far too expensive Dave, and I don't need 'supa-doopa' quality. Thanks anyway.

[HobbyCNC]

Far too expensive Dave, and I don't need 'supa-doopa' quality. Thanks anyway.

Wish you luck!

Dave

[AirbusPilot]

Help please,
I just want to buy a Jetjoe turbine kit. I've tried their web site with no luck. They didn't answer. Please could anyone that bought from these guys, tell me how to do it? Any details, most grateful. Thanks. Richard.

Hi Richard,

Please contact support@jetjoe or I can sell you one I am a dealer for Jetjoe fernandoabasolo@yahoo.com

Regards,

Fernando

[jet-mad]

Hi Fernando,
Well... it looks like no one has bought a Jetjoe turbine !. Yes, I've already sent emails to 'support'...no answers from them. I don't mind buying from you or anyone that can sell me a kit. Thanks. Richard.

[AirbusPilot]

Hi Fernando,
Well... it looks like no one has bought a Jetjoe turbine !. Yes, I've already sent emails to 'support'...no answers from them. I don't mind buying from you or anyone that can sell me a kit. Thanks. Richard.

Just send me an email and I will make the sell to you, I will accept paypal fernandoabasolo@yahoo.com

Here is a video of my yellow Stingray powered by a JJ-1400 http://www.youtube.com/watch?v=Fdo8XV5AcxE

[motorbikemike]

I too am having the same problem. Ive been trying to contact jetjoe for over a month now. Is the company in good standing or are things getting shaky. It's very odd that their not returning e-mails, purchase requests or phone calls. I'd like to deal with jetjoe direct... Any ideas?

What's going on?

[J Klenske]

I too am having the same problem. Ive been trying to contact jetjoe for over a month now. Is the company in good standing or are things getting shaky. It's very odd that their not returning e-mails, purchase requests or phone calls. I'd like to deal with jetjoe direct... Any ideas?

What's going on?


Well... Depending on the type of ejection seat your sitting in I think it would be wise to reach over your head and pull the two yellow loops down and cover you face with canvas or grab the two red handels on each side of you knees and hang on!

EJECT!!! EJECT!!!! EJECT!!!!!

[Marty C...]

Help please,
I just want to buy a Jetjoe turbine kit. I've tried their web site with no luck. They didn't answer. Please could anyone that bought from these guys, tell me how to do it? Any details, most grateful. Thanks. Richard.

Hi Richard, Well I dont want to sound negative about Jet Joe, but IMHO I would also recommend considering other options, just my opinion like I say and speaking from personal experiance with variety of turbine brands over the last 8 years... with JJ's people have had various level of success? getting these to run reliably OR to manufacturers specification so that said if $$ cost is your deal breaker, yes JJ or maybe even seriously worth considering shopping for a second hand turbine could be the go! ... Quality wise Wren are at the top of small engine class as far as reliabilty and performance as fasr as Iam conserned, Artes or Jet Central offer the Super Bee 14 lb thrust and are similar to Wren quality wise, both of these brands offer great back up after sales service and are well proven performers that deliver performance as advertised or better. The other bonus is Wren, Artes can offer local Australian service support, Iam not sure about the service situation locally for JetCat and Simjet but thats very important for me when choosing any turbine...

So where do you fly in Sydney anyway, just curious as Iam local also.....

[Boomerang1]

Are not Jet Joes also sold as Jet Lucky Turbines (JLT)? If so they are available from any Australian model shop that deals with Model Engines and that means most of them.

For what it's worth a member in my club has one. It's fitted to a Baby Boomerang and performance is unspectacular. It took a lot of fiddling to get it to this stage, definately not plug & play! He is sorry he did not take our advice & buy a better quality turbine and has just ordered a Jetcat P-70. - John.

[Marty C...]

Are not Jet Joes also sold as Jet Lucky Turbines (JLT)? If so they are available from any Australian model shop that deals with Model Engines and that means most of them.

For what it's worth a member in my club has one. It's fitted to a Baby Boomerang and performance is unspectacular. It took a lot of fiddling to get it to this stage, definately not plug & play! He is sorry he did not take our advice & buy a better quality turbine and has just ordered a Jetcat P-70. - John.

Good point re- JLT, I wonder are they offering local service support also ?

[AirbusPilot]

My opinion is that jetjoe turbines two year ago wasnt ready to sell, but now they are. the only bad thing is that they dont have a good or any instruction manual, but i am pretty sure that someone that have owned a turbine engine before could make it run.

Here is a link of my YA Stingray flying with a JJ-1400, I will install a second JJ-1400 on a YA F-18 Single and I will install a JJ-1800 when ready in a Jetlegend F-15.

http://www.youtube.com/watch?v=Fdo8XV5AcxE

[Boomerang1]

I wonder are they offering local service support also ?

Um.....Er......... well someone said that someone else said that they know this guy that......... :rolleyes:

But, having said that, how do you define 'local support & service'? Is having a dealer 3000 km away on the other side of the country who has a post office down the street to send an engine to Europe a qualification for 'local support & service'? Is a stock of a few common 'replace them yourself' spares good enough? Or should he have the equipment & expertise to rebuild, balance & test run all in house? Still, is there a huge difference between putting an engine back in a box & sending it to the other side of Sydney and putting an engine back in the box & sending it to Europe these days?

Can say this though, it helps a lot if you speak a language I understand & reply to any communications sent, which the manufacturers of my turbine do absolutely without fault. Would be nice to get some cakes though! :) - John.

[wildnloose]

There was a post on another forum of a U.S. dealer. Check out his page at jetjoeus.com

[Nony]

Far too expensive Dave, and I don't need 'supa-doopa' quality. Thanks anyway.

You can't afford anything less with a turbine spinning at 160,000 rpm... I have seen two...one was a piece of junk from the get go. It was never run, because it was found to be full of manufacturing flaws, the other one kept going into unstable combustion, and set the owners plane on fire twice... That does not give me much confidence in the brand.

You can buy cheap and fiddle with it all weekend long and maybe, just maybe you might get it to run...or you can get an established brand with a good track record and being flying instead...

[Boomerang1]

Update on my friend's Jet Joe (JLT) in the Baby Boomerang. The engine went bang in flight on the weekend. Lots of flames from the back (tailplane toasted) and bits of flaming debris falling from the engine. :eek: Something's now rattling inside the engine, back to the supplier, again. :(

Like Nony said, you can't afford anything less than 'supa-dupa' quality with a turbine spinning at 160,000 RPM. I'm beginning to think that if you cannot afford a top quality turbine you cannot afford turbines full stop. - John.

[jet-mad]

Thank you all guys, for your comments, but they do not answer my questions, that still stand:

1) Has anyone bought a JetJoe KIT directly from them?
2) How s/he do it?

Back to you.
Richard

[Note: I do not fly turbines; I do not want to; I do not want any other turbine, cheap or otherwise. I like to make turbines and experiment with them, I have made 5 and building my 6th now; the JetJoe is the one I want.]

[Nony]

the JetJoe is the one I want.]

You could take the metal from an empty coke can and build a better turbine using a rock as your only tool......

Good luck.

[Marty C...]

You could take the metal from an empty coke can and build a better turbine using a rock as your only tool......

Good luck.


:D Now thats funny Wayne......

John, Local service and support should be= Full Monty, and include anything from basic check ups ie.run and check performance is as it should be and maintaining factory spec or including complete crash rebuilds, stripping down replacing damaged components as needed and reassembly along with accurate professional shaft balancing etc, Simply sending to a third party sales rep is lame and aint cheap for the customer either, anyway not if the claim is in fact that they do have an established local service center or technician etc. This needs to be made clear by distributor for the guys looking to buy if they are under impression service/support is local when it is being shipped O/S....
:)

[Boomerang1]

Marty, do any turbines offer 'local service & support' in Oz? My Wren had to go back to the U.K. but it was a warranty issue. Wren, to their credit, had the engine back ASAP. Have you used Perth RC's 'local service & support' for yours or was it bought elsewhere? - John.

[Marty C...]

Marty, do any turbines offer 'local service & support' in Oz? My Wren had to go back to the U.K. but it was a warranty issue. Wren, to their credit, had the engine back ASAP. Have you used Perth RC's 'local service & support' for yours or was it bought elsewhere? - John.

John, No I have not had any experience with local service for Wren or dealt with Perth R/C, hows their after sales Wren support??? Iam curious, what about service turn around times?? if going back to UK?....
I have been living in Canada for last six years, having returned to Sydney late last year.... so pretty much all my stuff was originally purchased while living in the 'Great White North'... Iam not sure what the local situation is for all the brands but I do know that there is a new local sales and service center opening very soon for Jet Central (ARTES) and JetsMunt (Merlin). That means 'ALL' service/repairs, spares sales would be taken care of locally for those two, Iam not sure if they will service other brands at this point though.
That said with Wren I know even though their turbines are being shipped back to U.K. in some cases that would not bother me personally as Wren are first rate when customers are concerned... plus they speak our lingo, but have no first hand experience yet with service turn around period from Oz?
AMT NL are also quick with service turn around from Oz, I know this first hand as we 'burried' an Oly (so to speak) 'big time' on a UAV project we were working on recently and Benny at AMT NL had our rebuilt Oly engine back to us ready to go again in less than three weeks all up!!!

I personally reckon any local service center regardless of brand would have advantages over non-local service support facilities, its just so much easier for owners in Oz as far as after sales comunication, O/S shipping cost, customs issues and turn around time goes just would be easier on us jet flyers in Oz, and likely boost turbine sales for any manufacturer that will offer full local sales, service and local event support. It does work well for the larger U.S. market, as example shows first with RAM then JetCat followed suite when RAM closed its doors filling the U.S. service/ sales pitch values, the manufacturers of course just need to be able to back up with turbine sales volume to be sustainable...marketing 101 eh! :)

[acrored]

I will make any JetJoe turbine engine to run, I could balance again, check everything and bench test the engine or fly if you want. Just send it to me and I will repair ;)

I think for anyone that has built and owned a turbine engine before and has some expirience will be easy to make a USD599.00 turbine run and performe like a USD2000.00 turbine.

This is what I do with a JetJoe engine:

1.- Check fuel injector
2.- Remove the rear bearing oring
3.- Check Preload Spring so it has a pressure of 4kg at working leng
4.- Check lubrication pipe
5.- Make sure that you have intalled new inconel combustion camber

Here is a video of my Yellow Stingray powered by JetJoe :D

http://www.youtube.com/watch?v=Fdo8XV5AcxE

[woody410]

I attended the Superman 2006 this year and JetJoe was there with their engines set up and running. They seemed to start well and run up good. I wouln't mind having one myself. My best friend is buying one to put on his enforcer. JetJoe had an enforcer there powered by their engine and it flew extremely well and fast.

[g-rookie]

I attended the Superman 2006 this year and JetJoe was there with their engines set up and running. They seemed to start well and run up good. I wouln't mind having one myself. My best friend is buying one to put on his enforcer. JetJoe had an enforcer there powered by their engine and it flew extremely well and fast.

I was at Superman and this is the US Rep. info. and he is a nice guy.

Gabriel Brown
2129 Hayes
Portales NM, 88130
505-749-1970
www.JetJoeUS.com
service@jetjoeus.com

[mcjustis]

My opinion is that jetjoe turbines two year ago wasnt ready to sell, but now they are. the only bad thing is that they dont have a good or any instruction manual, but i am pretty sure that someone that have owned a turbine engine before could make it run.


So the manufacturer hasn't owned a turbine before?? If they can be made to run, why wouldn't the manufacturer do it instead of putting out a substandard product? I guess at this point if you purchase one, you get what you pay for...

[AirbusPilot]

So the manufacturer hasn't owned a turbine before?? If they can be made to run, why wouldn't the manufacturer do it instead of putting out a substandard product? I guess at this point if you purchase one, you get what you pay for...

Are you afiliate with a turbine manufacter or what????

What I said is "I dont like that Jetjoe engine came without a MANUAL so may be dificult for a first time turbine owner to make it run"

[mcjustis]

Airbus,
No, I'm not affilitated with any manufacturer of a turbine. I only made my own. I know what it takes to make them work correctly.
Would the printing cost of a manual put the price out of reach of an average Jetjoe owner?? I think these turbines are marketed more toward the less experienced modelers who would absolutely need a manual, especially with the track record they have for being unable to get ahold of. (which by the way was the whole reason for starting this thread)

Martin

[AirbusPilot]

Airbus,
No, I'm not affilitated with any manufacturer of a turbine. I only made my own. I know what it takes to make them work correctly.
Would the printing cost of a manual put the price out of reach of an average Jetjoe owner?? I think these turbines are marketed more toward the less experienced modelers who would absolutely need a manual, especially with the track record they have for being unable to get ahold of. (which by the way was the whole reason for starting this thread)

Martin

I am agree with you about a very good full color manual should not cost a lot but if you have bought other product from china, you will notice that they have about same problem, dont know why :confused: :confused: :confused:

[Sara]

I think it is not the printing cost but the difficulty of writing the manual. It takes a lot of time and effort to produce a good manual and when the people making the product don't have a good command of written English it must be impossible. Rather than writing a poor manual in "Chinglish" they don't bother with a manual at all.

Not only do the JetJoe ready-built engines come without a manual, the kit engines have very little in the way of instructions and I've had people trying to get hold of one of our manuals to help them. That's why Wren don't put manuals on-line. Joe did his original "research and development" by buying one of our kits and our plans, we don't intend to give him more help by giving access to our manuals.

Incidentally, colleagues of ours went to a trade fair in China, where someone tried to sell them a copy of their product. This DID have the instructions - a photocopy of their own instructions complete with their own name and address.

Sara Parish
Wren Turbines

[AirbusPilot]

I would write a full manual with full color pictures for two turbines :D

Just kiding but not a bad idea ;)

[It's going in !]

Well we bought 3 JJ1400 from Dave at Northwest Turbines. Very impressed with Dave's demonstration, quick turnaround, modification and total after sales involvement and backup. From order to hand was 10 days. And Northwest turbines create there our manuals. Not in colour and just text, but i've never owned or run a turbine, but with there simple demo's, instruction and what text you get, i had no problem setting up and running my turbine.

And very impressed i am too !

[Marty C...]

Well we bought 3 JJ1400 from Dave at Northwest Turbines. Very impressed with Dave's demonstration, quick turnaround, modification and total after sales involvement and backup. From order to hand was 10 days. And Northwest turbines create there our manuals. Not in colour and just text, but i've never owned or run a turbine, but with there simple demo's, instruction and what text you get, i had no problem setting up and running my turbine.

And very impressed i am too !

Would you mind listing what Dave's modifications to the JJ are?? some seem to be running ok after being modified, but just wondering what mods actually are and how much they add to JJ's advertised initial purchase cost....
Iam still yet to see one run/fly reliably at any of the major jet meets I have attended over last two years.

[It's going in !]

Not 100% on all the mods, but i know that he changes the fuel/bearing feed pipes and connectors for festo type, other odds and sods and uses a better fuel pump.

Run mine several times, with reliable starts every time, and 160,000 reached every time. Very smooth too.

give Dave Swarbrick an email at dave@northwestturbines.co.uk.

cheers

Ian

[jet-mad]

Well...Many thanks to all that contributed with their opinions, most appreciated. However, the fact is that nobody was able to help me, because, quite remarkably, no one (that I’ve heard of) bought a JetJoe engine Kit yet!. And after such a long time and many emails to Jetjoe and many other people, I finally got an answer from the man himself, Joe (from ‘support@jetjoe.com’ ).
Yes, he does have a Kit for a JJ-1200 engine.
After some thought, I ordered the 'Combo 3' Kit, at US$729, plus US$40 shipping to Sydney, Australia. It is a complete engine, with all the basic accessories to get it going fairly quickly, if all goes well. As my intention is to only run the engine on a bench, at this stage the accessories supplied with the engine appear to be sufficient for the task. They accept Paypal, so it was quick and painless.
My plan is to put this kit together and run the engine, and then to report here on the assembly progress and the test results (time permitting…I still got to make a living). I'll try to insert pics as I go along, if possible. This promises to be an interesting project, that could shed some light into the inner works of this affordable new engine. See you soon.
Richard

[jet-mad]

24-11-06 Today I finally received the kit for the JetJoe 1200 turbine. I could hardly contain my curiosity, but I must confess I was initially rather disappointed by the shoebox-size, quite ordinary small cardboard box (see pic, just 10x20x30cmm!). Don’t know why but somehow I was expecting a much larger box, something 2 or 3 times the size. In fact, after collecting the package from the local Post Office, it was a real surprise when I got back to find out that it was the turbine kit (I assumed it was something else I was expecting from an eBay auction, because of the size, the very light weight and also the surprisingly short time that it took to come all the way from Shanghai...just 7 days from the day I paid, amazing is our present world!). Well done Joe, thanks.
The 2nd Pic shows what’s inside. Everything is very well packed, with ‘bubble’ and foam, and my first impression is that the quality is very good. Now I’ll have to check in detail each part, and let you know soon. (I’ll try my best to be thorough and as fair as I can, all opinions will be my own and based on my experience and knowledge, which is limited of course!. I will also try to answer questions as I go along, if I can).
Richard.

[It's going in !]

I understand that it's best to change the fuel and bearing feed connectors to Feasto, as the ones used on jetjoe engines are very good at transferring heat to the fuel pipes, which after a few uses means that the fuel pipe and bearing feed pipes can 'kink' and cause running problems...

I was told this by Dave (the uk rep) but i've not had the front of mine yet to take a look to see whats under the blue cowl.

When you take the front of yours can you take a pic and post ?

cheers

Ian

[jet-mad]

I had a very good look at each component of the Jetjoe 1200 kit individually. Nothing was damaged in transport, and generally, the quality of workmanship is quite good where it counts, most machining obviously the result of CNC. It is a basic ‘no frills’ turbine engine, and it should work fine if properly assembled and installed. And here is the first problem, because absolutely no instructions are supplied with the kit, not a single written note, nothing.
Most of the engine comes partially assembled, meaning most parts held by just a couple of screws or so, so one gets a pretty good initial idea of the engine’s general assembly. The other parts: the tail cone, the shaft/wheels assy and the bearings are easy to work out. Unfortunately, there is nothing else for the rest, I mean for the connection, installation, running and care of the engine.
So, this kit it is not going to be easy for people that has no previous experience with turbines, or the ‘un-initiated’. This is a little disappointing.
Over the next few days I’ll check each part one by one, in greater detail, to see if I can detect any problems and all checks OK, before assembling and finally running this engine. See you soon.
Richard.

[captinnitro]

Way to go Richard! You should video some of your more crucial assemblies. You know if you video the whole assemble you might be able to sell it to other pilots on a budget.

[timfly1]

I have a JJ1400 Be very careful that you dont pull apart the front bearing, they come apart easy, loose the ceramic balls and you will have to by another. I have a jj1400 that I traded for and have yet to get it to run by it self new ECU batteries good pump etc. I'm trying to figure out what to use to seal the rear with, some say a bit of silicone for the front, but the rear? I have no clue. Its in pieces now and I think over the winter I'll have another go at getting it to run. It cost too much to send it to joe from the USA. Anyway if you look at a Wren 54 it goes together the same way. Never ever take the turbine wheel off the shaft. I would mark the compressure wheel some how so it goes on the same way, Make sure those little fuel tubes are clear by hooking up a propane bottle to them and lighting them before assembly all flames will be the same if they are good. Oil the bearings with fuel/oil mixture before assmbly. Search the web there is alot of information on small turbines that you can use.
Tim.

[jet-mad]

:) 1-12-06-
The JETJOE 1200 Combustion Chamber- Today I looked at the CC. It arrived inside the engine, loosely attached to the diffuser. It is a very good close fit to the NGV, and this is very important.
Although I’ve never actually seen one except pictures, it looks very similar to the Wren MW54 design. It is very small (short), and I was surprised to note that, although also held by the NGV, it is secured by just the pipes connections and the threaded glow-plug bush (my shortest burner is 120mm long and held by 3 brackets). No other bracket or attachment is obvious (I’ll try to gain access to the original instructions for the MW54 and so be able to compare and analyse the design of these engines in more detail).
The basic materials are good, meaning the quality of the brass tubes and the thin SS shell parts is good. The SS appears to be laser cut because of the neatness. The spot welding is also quite good.
The whole appearance of the CC however, is a little grotty, in that the fine gas brass tubes are a little messy in the way they are laid out around the shell, and the fuel ring is a little out of shape, together with the untidy tube bending and welding (untidy, but the welds are good). Although I’m sure this won’t have the least effect on the good functioning of the engine; it’s that . . .it just doesn’t look nice (am I being too grumpy here?). Internally, everything looks good and tidy.
I have checked the 12 very fine needle injectors and the other pipes for obstructions and all is OK. I took many shots of the CC, but attached the two I think best shows the areas. If anyone wants any other view, just ask.
[IMG]

See you soon. Richard.
(don't know what's happening with the pics, can't get them on the post... forgot how I did it! ...help anyone?)

[SWAT1]

Send them to pilot@kc.rr.com and ill post them if you want

[timfly1]

I think the reason why my motor wont run by it self is because the person who had it before me over heated it. Lots of blued steel on the turbine end of the shaft, also the rear bearing does not get enough fuel/oil. The mod for that is to increase the dia. of the lube tube that runs behind the diffuser to the shaft tunnel. I dont know if joe is making those mods but it is well worth the effort to do so. If we in the USA ever get a jetjoe rep. I would very much like to have him take a look at my motor. There is no dout that jetjoe motors run and run well if you keep them in good shape. Wren may have changed a lot of things in there MW 54. I would not try to compair motors except for assmbly purposes. Wren are far better and much more bucks, too much bucks.

Tim.

[wildnloose]

timfly1,
you may want to contact jetjoeus to see if they can be of assistance. they are supposed to be the us rep...

www.jetjoeus.com

[SWAT1]

Here are the pics

[timfly1]

I've been to that web site and nothing works. I wonder if there will be a real rep. for jetjoe. Maybe I'll biuld a motor based on the Phoeinx, I have a few parts and the drawings.
Tim.

[wildnloose]

I don't have a problem with the site at all (ie6 sp2). you may want to email him at service@jetjoeus.com to ask questions.

[jet-mad]

:) 4-12-06 JETJOE 1200 Parts.
The Diffuser. The Diffuser is nicely machined in Aluminium alloy (see pics), finish is good, obviously CNC. It is an assembly of 4 parts: The front, the diffuser proper, and 2 covers. They are all well machined, hole drilling is quite precise, as seen in the pic, view from the top, that shows hole alignment between the diffuser disc and the shaft Tunnel.
The front is a single piece that includes the intake bell. I checked the surface match with the compressor as it is excellent, losses should be small if properly adjusted for minimum gap.
The diffuser disk has 2 small round covers, the smaller one at the front, held by six csnk socket hex hd screws (nice ones), through the disc screw and secure the tunnel. All surfaces are close fit, and holes do fit in any of the six possible positions, although only one (un-marked) is the correct one due to the small slot on the cover that clears the squashed (restricted?) oil pipe (see pic). The pipe is SS, and obviously difficult to bend sharply. It looks a little squashed at the bend exiting the oil connecting screw, but don’t think it is a concern given its squashed (restricted?) end, near the front bearing.
The last (larger) cover fits at the back of the diffuser disc. It has eight 4mm holes and one 2mm hole for the oil pipe. It is held by 8 screws, 4 with a nut inserted near the head, I assume to increase the clearance with the combustion chamber (CC) (see pics). The purpose of this cover is unknown (for me) at this stage, it doesn’t seem to do anything for a living.
The Tunnel. The Tunnel has a rather stiff spring fitted inside, and a sliding steel tube that presents the preload to the bearings. All is close fit and well machined. I haven’t measured the spring force on the bearings yet, but it seems to be in the order of a Kg or so. The bearings are supported by ‘O’ rings that fit in a grove in the tunnel wall, around the outer bearing races. The front bearing is the only one axially secured, held by a recess in the tunnel and the small cover.
In short, a nicely machined part. Can’t comment about its design, my only concern at this stage is the rather sharp edge on the diffuser de-compression area (see pic). This edge is surely not going to help a laminar air flow, and will need correction at a later stage (after the test run). The rest looks pretty ordinary for a current model jet engine.
See you soon. Richard.
PS. Thanks Greg for posting those pics for me (yes, that was it! thanks).

[timfly1]

How is the shaft tunnel to NGV fit. On my jj1400 it is a poor fit, the shaft tunnel was gauld badly. Jeo sent me a new tunnal and cc free of charge, but the new tunnal still will not fit the NVG properly its as if the NGV is out of round where the tunnal mates with it. My spring was a very bad fit, I had to work hard to pull it out of the shaft tunnel, so I had to put the spring in my lathe to grind down the od. so it would be a nice fit. I'm going to increase the bearing oil tubes i.d. to make sure the rear bearing is getting enough oil. I think I'll take off the turbine and replace the rear bearing with a spair I have and then try to ballance the assembly as Wren discribes for home builders.
Tim.

[jet-mad]

:rolleyes:11-12-06 Some more thoughts about The Jetjoe 1200 Diffuser. Before going on with other parts of the engine, more should be said about the diffuser, and also about diffusers in general.
I failed to mention before that the internal ends of nearly all of the threaded holes are not de-burred at all, and this should be carefully done before any tests to avoid any thin aluminium ‘flakes’ coming loose during the operation of the engine, for the sake of the expensive bearings.
I should add at this point that I have been loaned a manual of an old Wren MW54 engine (thanks Tom), and this will allow me to compare these 2 engines in more detail to some extent and refer to similarities when (and if) required.
The first immediate observation was about the reason for the apparently useless rear cover. This cover is similar to the one shown on the Wren instructions and, together with a very fine metal mesh filter, it is originally intended as an air filter chamber for the bearings cooling air. Alas, my diffuser did not come with any metal filter mesh of any sort!
Generally, the diffuser has become a highly controversial part for the simple reason that involves many design constraints that are difficult (and very costly!) to measure. Personally, I never quite accepted the shape and position of the so-called ‘wedges’ and ‘vanes’ around the compressor wheel exit area. No doubt their designers have arrived at its shape and angles after experimentation. The wedge surely solves a particular and important problem: the need for a rigid support for the front intake of the compressor housing. But in my view, some things don’t quite add up. The angles of the faces of the wedge are obviously of upmost importance, and they look wrong to me.
Why? Well, they do not seem to match the angle of escape of the air from the compressor wheel. In fact the face nearest to the wheel (with the angle it has at the moment (about 10 degrees re the tangential axis at the point of escape) presents itself more like a blocking wall to the high speed air escaping from the tip of the compressor, and this seems to me a ‘brute force’ way of reducing the air speed. As I see it, the angle of escape at the tip of the compressor wheel is (in theory) about 45 degrees and it is constant, i.e., it is independent of the rotational speed or the mass of the fluid (be it gas or liquid). This happens because with gravitational forces, the acceleration of a mass does not depend on its mass, i.e., it is a constant value. In our particular case of a centrifugal force, the 2nd variable (the air escape speed) is itself a function of the rotational speed, in fact this being the only variable parameter (for all practical purposes) in our situation.
This fact can be very easily tested experimentally, with a short length (20mm) of fine cotton thread held near the tip of a rotating compressor wheel by a pair of thin twicers. Whether 10 rpm or 10,000 rpm the angle remains the same.
With this in mind, I think the lower face of the wedge should be about 40 degrees and the top about 50 (instead of about 28 degrees), and with just 4 wedges, and only long enough to clear the diameter of the holding screws, the wedges being there basically to provide support for the front intake and to aerodynamically ‘shape’ the screws.
As it is well known, the main function of a diffuser is to convert the kinetic energy of the air to pressure, at the expense of velocity and (very important!) with minimum losses! It seems obvious to me that anything that unduly obstructs the free flow of air is going to increase the losses, be it ‘wedges’, screws, vanes or whatever. Furthermore, even the angle of the ‘vanes’ of this diffuser do not seem to quite match the angle of escape (wrong or not!) of the wedges, imposing (…always in my view…please corrections are welcomed) yet another unwanted loss. And taking near 15% of the available area, they obstruct the airflow significantly.
It is interesting to note at this point that none of the zillions of commercial turbochargers currently in use around the world have vanes, or wedges, or supports, or anything at all in the air path (…and oh boy! sure they have money and time for experiments!).
With this in mind, later on I intent to make an exact copy of this part soon after the test run, but without wedges (perhaps just 4 and with different angles) nor vanes, and test it against the original, just to see what happens (…time permitting).
See you soon. Richard.
(Important Note: corrections are needed and comments welcomed at any time so we can all learn a little more, please feel free. Thanks).

[timfly1]

This would be interresting to try out if I ever get my JJ to run. There are lots of things I want to try thats one reason I traded for the JJ. Need a good running platform first. I do have some of the screen from Wren that I'm going to use in the JJ. I also have the building manual and drawings for the Wren MW 54 MK1. Many many changes since then but still some good info.
Tim.

[jet-mad]

:) 7-12-06 The Jetjoe 1200 Housing- The outer case looks like the one I have used for one of my engines, an ordinary SS coffee cup, straight out of the shelf of a supermarket. It is nicely drilled and finished (just drilled, no Laser here). It fits well on the diffuser and at the other end, on the NGV (see pics). But it has a rather annoying edge that reduces its diameter precisely were it meets the ‘O’ ring on the diffuser and makes its assembly very difficult (and disassembly too, see pics). I tried to flatten this edge, thinking ahead, in the many times this engine will most probably have to be opened, but with limited success. The material is very hard and difficult to hold properly on the lathe, without damaging or distorting it.
The holes around the cover do coincide more or less well on any position with the threaded holes in the diffuser and in the NGV, but really it only goes in one position (unmarked) determined by the glow-plug socket on the CC and its corresponding hole on the cover. The glow-plug is supplied with a fibre washer and screws into the CC socket, holding the CC to the cover, and allowing ignition of the gas during the start-up sequence. All of the holes match their respective positions very well and assembly is without problems here. The screws are good quality; black finish/ hex socket. One had damaged thread that luckily I was able to replace, as an extra one was included with the Kit.
A faint serial number is etched near the glow-plug and the ‘JetJoe’ logo on the opposite side (...were normally nobody would be able to see it???). It looks nice, though (see pics). See you soon. Richard.

[timfly1]

If you get something that is cone shaped you can spread out the covers edge just a little to alow the case to slipe over the o-ring. I have a tube of Corning high temp silicone grease that I use in big rockets put some of that onto the o-ring and it will help to seal the front of the case. You may have to heat the edge with a torch to red hot to do this. Heating the edge will do no harm to the case. Look at that hole, poor workmanship. I found the screws on my JJ to be a poor fit at best, screw holes did not line up very good at all, More than likely the tap they used was worn.
tIM

[jet-mad]

13-12-06- :rolleyes:
Some more thoughts about the Jetjoe 1200 Combustion Chamber – As I said before, I don’t quite like the design of the CC. Mainly because it is too complex. It has too many little tubes going everywhere and in particular, because of those fragile very fine hypodermic needles, so easy to damage (i.e. bend, squash and pull out of alignment) or block with fuel dirt of carbon residues. I can’t really think of anything going for the rotten things. And this CC is obviously, quite difficult to make (read expensive!). I’m sure there must be an easier way to do it, and with this in mind (and to save me the trouble of making one), I asked Joe (of Jetjoe turbines) to sell me a bare CC shell, with no tubes, no fuel lines, nothing welded, nothing inside, just the bare shell. And he provided me one (US$40.oo) that has just arrived (see Pic). I intend to re-engineer this CC in a way that, if possible, would be cheaper to make and easier to maintain, and would also retain the excellent performance of the present design. A difficult task, no doubt about that, but quite possible I think. I intent to base the burner on the use of a single tube, essentially the basic feature of all my CCs, that have worked so well to date under all kind of conditions and without any problems. And intend to test it against the one supplied with the kit, to see what happens (…time permitting). See you soon. Richard.

[timfly1]

I have made many of these based on Wrens design. The JJ cc is based on Wrens design. I'm sure theres room for improvment. With the proper tools a home builder can make one in about six hours. A sheet metal shop can make make many in one hour.
This winter I'm working on a micro spray nozzle to replace the needles, but at this scale I think even nozzles will be prone to clogging. Thats why we use very good filters. A sheet metal shop I know of can program there machines and turn these out very fast for them these are easy to manufacture. If I where to give them a SolidWorks model I could get them to make these for maybe $30.00 each if I buy 250 pcs.Simple would be good but I think you would have to drasticly change the design.

[mcjustis]

On the turbine I built I didn't use hypo needles for fuel, I used small tubing a little bit larger on the id than necessary and kinked the end of a small piece of wire. The wire is then pushed into the fuel tube with enough left hanging out so you could pull it out if clogged. The small wire keeps dirt out of the fuel tube, but if something does get in there you just pull the wire out and clean it out. Also no tiny needles to silver solder in. The od of the tube I use is about .080" so it's pretty easy to work with.
Martin

[jet-mad]

:) Hi Tim and Martin. Those are very good ideas, I think worth considering by anyone building a model jet engine. You didn't mention the sort of tubing and wire you used Martin, was it SS?, and the welding? layout? I'd appreciate more details if possible, please. Thanks. Richard.

[jet-mad]

:) 15-12-06
The Jetjoe 1200 Compressor- The compressor wheel appears to be a standard turbocharger wheel and is nicely finished; it is a very close fit in the shaft. Looks like it has been reduced or adjusted in diameter and perhaps in shape (it is hard to tell), it measures 53.91mm dia. and the rear face is not entirely flat (unlike all my other compressor wheels, that are flat), but it has a thicker section near the shaft bore (see pics). The shape seems to closely follow the Wren plans. This shape is probably related to the oil pipe that ends near the front bearing and also to air circulation, but it is not entirely clear at this stage (this is where instructions become so important, that I miss so much, even if they were just crude ‘chinglish’).
The shaft bore is 6mm dia ; the width of the blades at the tip (active area) measures about 4.1mm, which is about 0.8mm narrower (about 15%) than the width specified by Wren (4.9mm). The balancing has been achieved by a very shallow concentric milling (about 6mm wide by 0.5mm deep) on the rear face (see pic), and about 3mm from the edge of the wheel. I don’t think this would unduly weaken the wheel; it gives the operator very precise control over the static balance of the wheel (I’ve seen commercial wheels balanced by whole chunks milled out of the edge of the wheel! crude but it works; better? ...I don’t know).
The shaft- The shaft is another very nicely made part (see pic). It is hard steel; both ends have been grinded to size and fit the wheels perfectly, with no noticeable play at all. The wheel spacers already fitted on the shaft are also a very close fit and well finished. The compressor nut is aluminium, the turbine wheel nut is a std turbocharger nut (see pic), both are L/Hand Threaded. I spun-tested the shaft alone on the 2 bearings to about 50,000 rpm and it runs very quietly, with no vibration at all (as it should!).
The bearings- The two bearings are ceramic, made by GRW in Germany (see pic); one was in a sealed plastic bag, the other one was in a small un-sealed plastic bag, with no brand, but on close inspection they both look the same and appear to be from the same manufacturer. They are of std size: 16x8x6. See you soon. Richard.

[jet-mad]

:rolleyes: 17-12-06
Further thoughts about the Compressor Wheel. Yesterday I had to hang the Christmas lights on the pine tree on our front yard, and had also to replace many of the small globes which I found had the terminals corroded after only one year in the box, and so wasted most of the day. Anyway, later on, on a closer inspection of the compressor wheel, I noticed that when partially assembled together with the diffuser and tunnel, the edge of the compressor wheel outer rim does not correctly align with the surface of the diffuser (or is it meant to be like that? ...don’t know, no instructions!); there is approx. a 0.8mm step (the wheel overhanging the diffuser, see pic). This step could very well be the result of the width missing on the wheel blade (about 0.8mm, remember?).
Removing the shaft spacer allowed me to temporarily re-align both (see pic), but at the expense of an increased gap at the other side, i.e. between the compressor and the intake cover. This gap, if left un-checked, could have some pretty bad effect on the compressor-stage performance, I’d say (on the other hand, it could all very well work perfectly as-is, who knows? the test run will tell).
As I see it, there are many ways of solving this problem; the easiest I think is by reducing the thickness of the spacer until both surfaces are level. Then ‘moving’ the intake cover closer to the wheel to reduce the increased wheel-intake cover gap, by removing the required metal from the intake cover, on the lathe.
Unfortunately the wall here is quite thin as it is at the moment (about 2mm) and the required thickness to remove is probably of the order of 1mm, which would leave a wall too thin for comfort. But any other solution, like reducing the width of the ‘wedges’ requires more complex changes that complicates the adjustment and could also have some unforeseen consequences. This change will probably require a new front cover, we will see.
Now; in this zone, where air has the highest velocity, the area is being reduced by approx. 15% (about 1.35cm square); this cross-area will be missing from the wheel air exhaust. Because of the narrower blade width and given similar conditions, the air flow could be about 15% less when compared with Wren’s wheel (none of my other turbine compressor wheels have less than 5mm here, one has 6.5mm).
I’ve noticed too that Wren specifies a 3 degree slope angle on the front face of their diffusers, at the base of the ‘wedges’ where it meets the compressor and to match the compressor’s surface slope (see pic); this angle is not present in this diffuser, the surface is flat. There is a small step on the outer edge though (see pic), which may be the result of wrong or missing CNC commands, and that could represent the 3 degree slope had it been fully processed (in this area it is a rather difficult task to perform well if just a basic CNC machine is used).
Anyway, I think we’d all agree the overall picture is becoming more complicated than we first thought. And more is to come. See you soon. Richard.

[jet-mad]

:rolleyes: 19-12-06 The Jetjoe 1200 Turbine Wheel.
The turbine wheel it’s got to be the most critical part, due to the importance it has on the whole of the engine. The wheel is a 55mm class (measured: 54.77mm) sized and balanced, the NGV total gap measures 0.46mm (0.23mm peripheral gap).
The cast surface is average. There is the odd imperfection, but nothing remarkable. I can’t comment on the blade shape, angle or section itself as I lack sufficient knowledge, but they look pretty average and very similar to the ones I have used. Perhaps the leading edge could have been better shaped, a little less blunt (see pic).
The balancing ring cast into the turbine wheel has been completely ignored during balancing; a ground shallow concentric slot was used instead (much like the one on the compressor) on the internal side of the wheel (see pic). The machined surfaces are excellent and the bore fit on the shaft is superb, a real close fit (pic).
Yes, machining in good, unfortunately its accuracy deserves a comment. I measured about 0.6 degree misalignment on the bore axis re the shaft axis (see pic). This indicates a problem with the positioning of the wheel blank on the boring jig, with the jig itself or with the boring centring. This operation (boring) is very delicate because of the metal hardness and quite easily can result in a misaligned hole. The ‘wobbling’ is clearly noticeable by lightly spinning the loose wheel on the end of a shaft (see movie). The outer rim edge (at the root of the blades) has been machined after boring and referenced to the bore. As a result, the rim has been only partially surfaced, on both sides of the wheel (pic). Luckily there is still just enough ‘meat’ to finish it properly (if correctly re-aligned in a jig!). However, this would also require re-boring, hub re-surfacing and an insert (not an easy job!).
To the best of my knowledge I don’t think the wobbling could affect the functioning of the engine as such, but obviously it is not going to be kind on the bearings. It could result in unwanted vibration, but it is hard to guess its effect at this stage. I have always been very careful with this aspect of my earlier wheels and don’t have previous experience with this problem; the test run will tell. But...I wouldn’t be using this wheel with any confidence for extended periods, and so, I (presumably) have 3 basic options: 1) rework the wheel, 2) return the wheel for exchange, or 3) order a new one.
After some thinking, I chose to order another wheel because in doing so, I end up with a handy spare wheel for experiments (exchange would cost ‘shipping’ money anyway). But I intend to order a blank, ‘as-cast’ wheel. It is probably cheaper and I would be able to finish it and so retain control on its final accuracy (hopefully; it isn’t an easy job). And there you are. The pictures show the wheel and the partially machined outer rim. See you soon. Richard.

[Sara]

It's interesting to see that Jetjoe STILL isn't using the balancing ring. His early engines all had incisions like this in the hub and it's amazing to see that it's still not being done correctly. I'm sure the people who have been giving him help and advice about improving the engines will have told him how it should be done.

The reason for a balancing ring is because castings can never be exact enough for turbine wheels to balance properly, there will always be a slight imbalance. The wheels have a "sacrificial ring" designed so that material can be taken from there to correct the imbalance. Taking material from elsewhere may weaken the wheel.

All Wren turbine wheels are vacuum cast in Inconel at a specialist foundry. Then they are examined for defects, using Xrays and other tests. One of the standards of the aerospace certification we use is that there must be NO DAMAGE WHATSOEVER to the hub, and any wheel with defects - even slight surface ones - must be scrapped. So a wheel with a "JetJoe balance" incision in the hub would be regarded as defective, even if it had originally passed some sort of certification.

It appears that "Joe" either doesn't know what the ring is for, or doesn't care!

Sara Parish
Wren Turbines

[Turbo-Tom]

I'm also quite amazed that Joe is still using the compressor wheel with the vane tips too small. It's probably a result of not having a better suitable wheel available locally. But it's really funny that Joe doesn't modify the diffuser to provide the proper clearance.

Richard, the only way to get proper compressor wheel clearance would be to reduce the width of the diffuser vanes by about 0.6mm on a lathe. Yet, this requires many more modifications that cannot be done easily and quickly. Been there, done that (about three years ago). This particular engine now has only got two or three of the major parts in original condition, everything else had to be modified. But it's running and producing specified thrust finally and a friend of mine who's the current owner of the engine, is flying it in a jet model for more than one year by now.

But to be honest, I would just give the whole thing a try and assemble the package as received from Joe. If the engine won't work properly, I would simply ask for a refund and be quite curious about the reaction of Joe...

There's only one thing that you cannot complain about - you have been warned by several group members about the possible shortcomings of this engine.

Good luck,
Thomas

[HobbyCNC]

Far too expensive Dave, and I don't need 'supa-doopa' quality. Thanks anyway.

A quote from post #3.
Ya got your wish and you're monies worth! :-((

"JetJoe..for those that would rather fiddle than fly"

Bye Bye!

Dave

[jet-mad]

:) 20-12-06 The JETJOE 1200
The NGV. The Nozzle Guide Vane is nicely cast and machined (see pics), couldn’t see anything wrong with it. The casting quality is excellent and so is the surface finish, it should work very well. The tunnel is a close fit in it, so is the CC.
The tail-cone.
This part comes fully assembled (see pics). It is nicely formed (no welds) and finished, all SS. The inner cone is held, not by flat (aerodynamic) supporting vanes but by round (4mm OD) tubes and cup screws and nuts (see pic). I don’t like the idea of having tubes here because of the turbulence they obviously must create in this zone of nearly supersonic hot gas flow, other than it is simple (... and cheap!). I’d like to find out what difference does it make the tail-cone to the thrust of this engine and, if the tubes have any adverse effects at all. I’ll run some tests later on, if I can. And that’s all for the ‘tail’. See you soon. Richard.

[jet-mad]

:o Thomas, you are absolutely correct; I’ll have to ‘peel’ the redundant thickness out of the vanes. And Sara...well, I’m sure what follows will interest you.
In the mean time, I’d like to wish everyone a Merry Christmas and Happy New Year. Richard.

[jet-mad]

:rolleyes: 20-12-06 More about the Jetjoe 1200 kit turbine wheels.
(Well... I think this will definitely horrify Sara).
As it turned out, the as-cast wheel wasn’t to be as Joe couldn’t supply a blank ‘as-cast’ wheel. I had to order a finished one (US$90.00+US$20.00 postage). The wheel arrived in due course and yes, it is a ‘good one’ (see pic). Apart from a rather heavy cut on the internal side for balancing and a slightly deformed leading edge on one of the blades (see pics), it looks good. (I am inclined to not to touch the blade, but question is: is it possible to safely flatten an Inconel blade without long-term ill consequences? comments anyone?). I couldn’t see any marks on the blade that could indicate an impact of some sort; I suspect could be a defect of the casting mould itself.
Most of the blades have been filed to flatten the casting marks, but four blades still had some rather thick burrs (see pic), which I intend to remove later on after the initial tests. The balancing heavy cut was milled (not ground as in the first wheel), and indicates some large initial mass unbalance. I measured the thickness of the blades on the opposite side: 1.10mm (against 1.21mm).
Both wheels look different, probably from different batches or even perhaps from different manufacturers. I could note that the blades on this wheel are slightly thicker and the angle slightly smaller than the ones on the first wheel (perhaps 1 or 2 degrees difference), also the trailing edges on the first wheel are razor sharp as compared with this wheel. Balancing is excellent, with no detectable wobbling at all, and hub and bore surfacing very good, and a close fit on the shaft as well. So I now have 2 wheels (it was my choice), and we will see the differences in performance when tested ‘as-is’, if any.
There was no certification/x-ray furnished with the wheel, the material supposed to be Inconel 718 (or 625?). I tried with a small magnet on the wheel and on the NGV, and they are definitely non-magnetic (like Inconel and standard SS). To the best of my knowledge I think it is extremely difficult to determine the true nature of the alloy with any degree of accuracy, with commonly available tools (anyone tried a magnet on the turbine wheel or the NGV?; is it possible to verify the basic nature of the alloy with a magnet or some other ordinary tool or method? (comments anyone?). See you soon. Richard.

[Turbo-Tom]

Oh my God! I get a rollercoaster down my spine when I see this kind of balancing. Richard, if possible at all, please try to return the second wheel to Joe. Either try to get a refund or to get another wheel in return for this. It is a "lethal mistake" (initially for the turbine wheel, but if you use it, who knows for whom) to balance any kind of rotor with a router bit with sharp edges. In the corners of these slots you will get stress accumulation and the wheel WILL fail there. Maybe not during the first one hundred runs but this thing is definitely a time bomb. Please do yourself a favor and don't use it. It's not uncommon to use a mill to balance rotating equipment, but if done so, a router with a radius at the tip has to be used. I attached a photo of a titanium compressor impeller (Holset) which is balanced this way.

In your situation, I would rather prefer the first turbine wheel with the ground balancing mark since this at least hasn't got sharp edges.

On the other hand, slight bending of cast inconel parts is possible. Yet, the part should be tested for cracks afterwards (dye penetration). I know of several homebuilders in Germany who used to twist the blades of cast turbine wheels to close down the flow area a little for use in a shaft power engine. On the other hand, these engines usually run at significantly lower speeds than their thrust counterparts.

I'm not sure which material Joe is using for the cast components, yet I guess the NGV is cast stainless since when running, there's heavy hot corrosion on the surface and also some cracking can be found due to thermal cycling (not too uncommon on "real engines" as well so no need to worry if no loss of material is to be expected). But to find this after maybe only 20 starts is a cause to worry. Anyway, as I told before, this certain engine is running allright for more than a flight season with probably 50 flights. In this engine, still the original turbine wheel is used, so far without problems. But I told the new owner about the possible shortcomings and to take care when he runs up the engine to speed.

I really don't know why Joe is using so little common sense on his turbines. He probably hasn't read any machining handbook and didn't do any calculations on centrifugal stress in these cast components. If all of his engines are built like this, I would definitely recommend not to buy any!

Merry Christmas,

Thomas

[HobbyCNC]

I see quality at JJ is improving! They haven't learned a thing in over 2 years! Who's the first to get killed?

Dave

[AirbusPilot]

I see quality at JJ is improving! They haven't learned a thing in over 2 years! Who's the first to get killed?

Dave

First I have to said that I am a JetJoe dealer for Chile.

Jet-Mad, I am pretty sure that Joe get turbines wheel from two manufactures because I have seen the difference in my engines too.

About turbine wheel balance, I have seen pictures at RCuniverse showing balance job that looks a lot worst or more dangerous from others well known manufacturers and anybody said that they dont know how to do it.

JetJoe have sold more than 2000 engines in the last couple of years and we have read about bearing failures, combustion cambers and others, but never, never a turbine wheel failure.

Merry Xmast to all here at RCGroups :D

[HobbyCNC]

First I have to said that I am a JetJoe dealer for Chile.

Jet-Mad, I am pretty sure that Joe get turbines wheel from two manufactures because I have seen the difference in my engines too.

About turbine wheel balance, I have seen pictures at RCuniverse showing balance job that looks a lot worst or more dangerous from others well known manufacturers and anybody said that they dont know how to do it.

JetJoe have sold more than 2000 engines in the last couple of years and we have read about bearing failures, combustion cambers and others, but never, never a turbine wheel failure.

Merry Xmast to all here at RCGroups :D

At over 2,000 units sold, how many actualy run? How long before a repair is required? Just read the extensive posts and I'll bet NONE make past 10 hours. Do you have pictures (proof) of the "others" factory balanced as poorly as JJ?
I stand by my statement: "JetJoe, for those that would rather fiddle than fly"

Merry Christmas too!

Dave

[AirbusPilot]

At over 2,000 units sold, how many actualy run? How long before a repair is required? Just read the extensive posts and I'll bet NONE make past 10 hours. Do you have pictures (proof) of the "others" factory balanced as poorly as JJ?
I stand by my statement: "JetJoe, for those that would rather fiddle than fly"

Merry Christmas too!

Dave

You could find more about jetjoe safety here http://www.rcuniverse.com/forum/m_3141723/mpage_1/key_jetjoe/tm.htm

Merry Xmast

[Turbo-Tom]

That's quite some funny argueing ;).

If "cheap" manufacturer "A" produces bad quality and doesn't use common sense and good engineering parctics, and you find the same thing on a product by a well-established manufacturer "B", then the craftmanship of manufacturer "A" couldn't have been that bad.

I tell you, both "A" and "B" are producing crap, even if manufacturer "B" is usually known for decent quality. They may have had a problem with quality control or just a new employee, not yet experienced enough.

There are areas in a turbine engine where there's room for compromise but most definitely not so at the rotating assembly! For my own part, since collaborating with a turbine manufacturer, I know which parts to reject or scrap. This turbine wheel is definitely one of those. It doesn't matter how many engines are already sold (makes the situation only worse) and apparently runnig without problems (which I doubt at least in case of the JJ1200). A balancing job like this WILL eventually lead to a hub fracture. It's just one doesn't know when. It may last one hour and twenty cycles or 500 hours and 10,000 cycles. But probably no longer. If this turbine wheel is used in a test bed engine that's just operated for display purposes, you may be fine when limiting RPM to 50% but that's not the purpose that most of the customers bought their engines for.

I once owned one of these enignes and I know what I'm talking about. But what did I read some day? The cleverest are those who learn form mistakes of others... ;)

Merry Christmas,
Thomas

[jet-mad]

I trust you all had a happy Christmas and very nice presents! (...a turbine anybody?)
I would have thought Dave, that you can ‘fly’ thanks to ‘those who rather fiddle than fly’; don’t forget that ‘fiddlers’ developed the engine that now allows you to ‘fly’, as you say. (Kurt Schreckling, Mike Murphy and Thomas Kemp, amongst the best well known ‘fiddlers’).
I tend to agree with Thomas thinking. An Inconel hot bit of wheel flying in my direction at supersonic speed is something I would rather try to avoid at all costs (wouldn’t you?). And the idea of changing the molecular structure by bending the blade after it has been cast is a little worrying, a ’time bomb’ as you quite rightly describe it. The sensible thing to do here is to have this wheel exchanged if possible; I’ll contact Joe, and see what he has to say about this.
I’m not entirely sure what ‘AirbusPilot’ is trying to say here; is it that there are other manufacturers of turbines that do not know how to properly balance the wheels?; that there are pics of wheels showing bad balancing practices by those manufacturers? If this is the case ‘AirbusPilot’, I (and I’d imagine many others) would like to have more details please (links or the pics please); this is very interesting, I think. Thanks. Also ‘AirbusPilot’, I find hard to believe that out of the more than 2000 engines you mention, I was the only ‘unlucky’ one to receive all those dodgy parts combined in the just one engine. And what about if my wheel is the only one that has been balanced this way... and it explodes at the first test-run? So, question is: have you seen any other of your wheels balanced this way before? or that even looks like my wheel? (pic if possible, please). If so, then I could begin to believe that this practice is (so far) somewhat safe. However, I would definitely need some kind of proof, otherwise I’d rather stick with the universally well tried and known: ‘better safe than sorry’. See you soon. Richard.

[Graeme Marion]

Duh ????
jet-mad
Today 02:52 PM
I’m not entirely sure what ‘AirbusPilot’ is trying to say here; AirbusPilot
You could find more about jetjoe safety here http://www.rcuniverse.com/forum/m_3141723/mpage_1/key_jetjoe/tm.htm
Is JetJoe likely to be dangerous ?
Yes 32% (59)
No 67% (121)

Total Votes : 180

It looks like you are in the minority.

[Graeme Marion]

Yesterday 02:52 PM
jet-mad
I’m not entirely sure what ‘AirbusPilot’ is trying to say here; Dec 24, 2006 10:16 PM
AirbusPilot Quote:
JetJoe have sold more than 2000 engines in the last couple of years and we have read about bearing failures, combustion cambers and others, but never, never a turbine wheel failure. Perhaps you know better.
Yesterday 02:52 PM
jet-mad
I (and I’d imagine many others) would like to have more details please (links or the pics please); this is very interesting, I think.
Yes jet-mad, show us the links and the pictures of these exploded JJ turbines.

[AirbusPilot]

Hi All,

When I bought my first JJ-1400 (S/N 650 or so), I read so many things about turbine wheel material in JJ engines that I looked for a turbocharger expert advice (one of biggest shops in Chile) and he told me that those wheels were made from inconel, also he rebalance my turbine.
Like I am an Airline Pilot and I need that job for living so I don't want to loose one eye playing with a microturbine I made like big airplanes turbine manufacturer do, so I ran my engine so it could fail, I starter the thing I make it ran to full speed (160K Rpm), what happen to my engine was two rear bearing failures and one old SS combustion camber failure, but nothing wrong with rotating parts or NGV.
My first engine has logged about 10 hours now, 6 of them are flying the other 4 playing on the ground.
Maybe my testing are not long enough but I would like to hear someone that could test JJ engines till the turbine wheel fail so we may know how many hours or runs are OK for this kind of engines.

Cheers,

Airbuspilot

[joeflier]

Airbus,
Where do you get your information from? I find it hard to believe that Jetjoe has sold 2000 turbines (maybe you ment 200).

There are about 800 turbine waiver holders in the USA, and how many turbine modellers worldwide..... 3000, 4000 ?? If there were 2000 JJ's out there half of the turbine pilots would have one. I attend several several jet meets a year and have seen only one JJ turbine.

How many JJ dealers are there worldwide and how many have you actually sold?

Joe

[jet-mad]

I must apologize to (no name?) ‘AirbusPilot’, I should have followed his link before my last posting. I’ve read most of the relevant postings in the link provided, in particular looked at the 6 pics of JJ balanced wheels. It was very interesting to see that the 4th one definitely looks like my wheel; this wheel also has a rather deep cut, which shows there is a lot of mass in the wheel casting to balance out. The wheels appear to have been in use, because of the surface decolouration (comments anyone?), and most of them look like my second wheel, I mean: from the same supplier. In a way, it is a little comforting to see that similar wheels have been in use... and still are in one piece (...or were, at the time of the pics!). I picked from one of the postings that the NGV could be SS; is this so?
In any case, I’m growing a little uneasy about this whole ‘wheel’ subject, and I’m thinking about taking some precautions during the tests, until the ‘air clears’; perhaps running the engine inside a larger steel tube or something along the lines.
And now, the 60 million question...Has anyone seen a JJ wheel failure at all? (pics please, thanks). I tend to think that if in that many years and after some 2,000 engines (mine is #2064) NOBODY have seen, knows of or can produce PROOF of a wheel failure...well, JJ wheels must be somewhat safe to use despite their ‘savage balancing’! don’t you think?. May be later on, for peace of mind, I’ll order one from Horace, but for now, I’ll give these wheels a go.
If I can, I’ll try to exceed the rpm ratings of these 2 wheels (160K) under safe and controlled conditions during one of the last tests, to 200K or higher if possible, although this engine will most likely require some changes or ‘some external help’ to reach those levels. That should hopefully clear this subject once and for all. Richard.

[Graeme Marion]

As you know, I live in Brisbane which is by no means a big city. I know three local very satisfied JJ engine users. I am sure there are others.

I have on order a JJ 1200 MK2 kit. That is why I was interested to see what you had to say on this forum.

I will have the help of Ken Jack, a local turbine expert, to help me assemble and balance it. I want to learn how to do my own maintenance on this engine. In other words fiddle with it.

For people who don't want to fiddle with their turbines, buy a Wren and let them do the servicing.

If you want a Rolls Royce engine expect to pay Rolls Royce prices. I can't afford a Rolls Royce engine, but I can afford a JJ and I know that they work.

[J Klenske]

Airbus,
Where do you get your information from? I find it hard to believe that Jetjoe has sold 2000 turbines (maybe you ment 200).

There are about 800 turbine waiver holders in the USA, and how many turbine modellers worldwide..... 3000, 4000 ?? If there were 2000 JJ's out there half of the turbine pilots would have one. I attend several several jet meets a year and have seen only one JJ turbine.

How many JJ dealers are there worldwide and how many have you actually sold?

Joe


The S/N on my JetCat P60 is 6500. I purchased it new in July of 06

[joeflier]

J Klenske,
Thank you for that bit of information. Not sure what it has to do with the number of JJ's produced.

Joe

[jet-mad]

:) 26-12-06 - The Jetjoe 1200 Kit accessories. This engine kit comes complete with almost all the necessary bits and pieces to get it going. There is a Fuel Pump, a Control box, a starter, a 7.2V Nicad Battery Pack, a set of ‘Festo’ fuel connectors, two 3mm ID x 50cm lengths of plastic tubing (one clear, the other orange), a Glow Plug, and a mysterious short cable with croc connectors on one end and a plug that fits in the control box on the other, for unknown (at this stage) purposes.
The battery.
The battery is a std Sanyo KR-1800SC 7.2V Nicad 6-cell Pack (see pic01), it should be more than enough to start and run this engine quite a few times, I’d say. However, as received, it was full of surprises.
The first one was that the connector that was fitted to the cable (pic02) apparently didn’t fit any of the four sockets in the control box, not even the starter’s socket. Because I couldn’t easily locate a local source for these (rare) 6-pin connectors, I decided to change the connectors on the battery, the starter and the control box as well. It wasn’t until I tried to remove the battery connector (fortunately, it was the first one!) that I found out the ‘connector’ had actually been supplied with a socket plugged on it (???)(pic03), so well coupled to each other that the joint was undetectable. What I thought were the pins, were in fact the socket solder/wiring pins and not the pins of the plug itself at all. Once I pulled the socket from the plug, I found to my relief that the plug would fit the box sockets (ah...those instructions!). [Why on earth a pcb socket was supplied plugged on the battery plug? ... I don’t know].
The second surprise was that when I checked the voltage, it measured just 3.3V. This is very unusual for a new battery, but more surprising was the fact that it failed to take any charge at all. It was then that (on close inspection again) I realized that the cable’s polarity appeared to be reversed (see pic04 ‘before opening’), and on cutting the insulation open and removing the end-cover, this proved to be the case (see pic05 ‘after opening’). The cables were soldered to the battery, and so it was a quick procedure to correct the mistake (although not the best for the cells!). Luckily the battery recovered quite well when recharged.
The Fuel Pump.
The Fuel Pump with the kit is made by JetJoe. It came with a short clear plastic pipe looping the input and the output connections, with some fuel just visible inside (see pic06). It has a very faint ‘JetJoe’ logo etched on one side, a ‘DO NOT RUN DRY’ on the opposite side, and ‘6V’ near the positive terminal. The motor is ‘NICHIBO’, the overall pump dimensions are 24mm dia. x 54mm long, including fuel connections. Weight is about 62 gr. It starts turning with about 1 volt, and current is about 500mA; it runs very fast with 3 volts. I think it will need about 1.5 volt for normal use. I can measure the max. fuel pressure, but I haven’t had the time (I’ll try to do it later on, during the test run). I pulled it apart to see its construction (see pic07). It is a std ‘gear’ pump, it looks well built, internal surface finish and parts fit is quite good, it should perform well. Looks like the body and the cover plate are made of aluminium and the gears of steel. The cover plate holds the fuel connections and has no locating pins, so its position can shift during use if not treated with care (this should be easy to correct I think, installing a couple of pins, preferably before running the pump at all); it is sealed with a thin synthetic O-ring gasket (see pic). By adjusting the 2 holding screws it is possible to squeeze the gasket and so adjust the amount of play between the gears and the plate (too much pressure stops the pump). At just US$30 I think it is very good value, although JetJoe does not recommend this pump for airborne installations (I don’t know why, comments anyone?...’AirbusPilot’?).
The Control Box.
The ‘Micro Turbine Bench Control Unit’ box is intended for manually controlling the fuel pump and the starter’s electric motor while test-running the engine on a bench (... it just occurred to me that the mysterious cable with the croc clips could very well be for the glow plug!). The C.Box measures 80x125x40mm, on top it has a rotary knob, marked ‘Fuel Pump Cntrl’, a recessed pushbutton marked ‘Starter Cntrl’ and a ‘Charge Light’ LED(see pics08-09a); and 4 sockets on one end. Since no instructions were supplied, I had to open the box to check the electronics and so find out how it was supposed to be connected up (...when the instructions are missing it helps if your line of work is electronics!).
Two of the connectors are green and the other two are red, all are mechanically identical. A red one is marked ‘Starter Battery (7.2-9.6V)’ and is obviously for the battery, the other red one, ‘Starter’, for the starter electric motor; a green one ‘Fuel Pump (4.8V)’ for the pump and the last green one is marked ‘Battery (4.8V) Recharge’ and I don’t have a clue what it is for, as there aren’t any rechargeable batteries in the box (see pic09b, only an empty ‘AA’ battery holder).
The CCT is a simple duty cycle control based on a dual 555 (556). It looks like it has been modified a few times, I couldn’t detect a connection with the required voltage for a glow plug. Using an external Power Supply set to 7.2V, I tested the box with the pump and it worked well, but was not satisfied with the effective speed control the C.Box was providing to the pump motor, particularly at very low rpms.
On the other hand, this C.Box if of no importance if the engine is used in a plane because it isn’t used at all in that case.
The Starter.
Basically this is a handle made of a 215mm long aluminium bar (30x6mm) with a ‘Speed 300-6V’ electric motor interference fitted on a hole on one end (pic10). A robust micro-switch, connected in series with the motor is screwed on one side half way up the bar; the connecting cable with the plug on the other end, is polarized and about a meter long. The motor has an aluminium ‘drum’ press-fitted on the shaft with a rubber grommet inserted in the bore (very much like a miniature I.C.Engine field starter, see pic11). The grommet’s hole fits more or less well on the rounded end of the compressor nut. I imagine that after a few starts it should take its shape OK, and the grommet is easy enough to replace when worn out.
In short, the starter is very simple, well built and it should work very well and without any problems, and it should also work OK for starting engines that have easy access, as in simple model plane installations (external engines and the like).
The other bits and pieces.
All the necessary screws for the engine are supplied and are good quality. The screws for the NGV (8) and for the case and front cover (10) are all SS/hex cups. The rest are steel/black hex cups (10). There are other screws for the straps.
The strap is std type, supplied flat, in 2 parts, SS, nicely finished, no sharp edges, it needs to be shaped before use.
The much talked about spring came out of the tunnel quite easily in this engine, and it doesn’t rub on the shaft, as far as I could see. It is 4 turn-21mm long, and I measured a load of approx. 3.1kg at 15mm.
A ‘Shanghai CS Model Ltd’ 1.5V Glow Plug is included (pic12); its filament appears to have been pulled out just a little (pic13).
Also supplied is a nice in-line aluminium fuel filter. Inside it has 2 fine mesh discs (pic14), that should be enough, I think, to stop particles large enough to block the thin injector needles.
The external front cover is made of very nice looking thin blue anodised aluminium (pic15), very well finished, fits very well and it looks great on the engine.
There is also a TPM-4 ‘Y’ fuel line connector, and 3 ceramic 47nF capacitors, for noise filtering, I imagine (no instructions, pic 16).
And this ends the engine kit parts analysis. If anyone wants more details, just ask.
The next phase is the test-run. All that remains now is to finally assemble this engine ‘as-is’, complete the auxiliary equipment and run it. If possible I’ll try to save the ceramic bearings and use ordinary ones because I suspect the rear bearing will run dry for the ‘as-is’ test due to the ‘venturi’ suction generated by the compressor step. If anybody wants something in particular tested, let us know.
I would have liked to have RPM and Temperature measuring accessories, but this is not included with this kit, these components are optional. I will have to make them for this engine, so to have some accurate references while testing.
Temperature is not a problem, but rpm is. Earlier I failed to mention that the compressor nut has a very strong tiny magnet inserted at the bottom of the threaded hole (not in the centre, I may add; the flats of the nut aren’t symmetrical either, this nut could need balancing). I plan to use a sensitive Hall Effect sensor with the supplied compressor magnet-nut and a frequency counter, to implement a simple rpm measuring system. This could take some time to get going, don’t know. See you soon. Richard.

[jet-mad]

Well Graeme... go for it! it is a ‘fiddlers’ heaven! (you and Jack sure are going to have lots of fun). Richard.

[Graeme Marion]

Thanks Richard.

[AirbusPilot]

Jet-Mad,

I have never used a JetJoe Pump or that equipment that you have in your last pics. I just run JJ engines with Nades Full Auto Start and FlightWorks Pump. Anyway I want to buy one JJ pump to use it with a smoke system.

Cheers,

Fernando
AirbusPilot

[Marty C...]

Duh ????

Is JetJoe likely to be dangerous ?
Yes 32% (59)
No 67% (121)

Total Votes : 180

It looks like you are in the minority.

Yeah not likely to be dangerous I would have to agree......well sort of,
As since day one 'ALL' stock JJ's as delivered do not seem to run even ok unless modified????? guys that is the bottom line simply put. The JJ does not run to factory specifications unless MODIFIED, tinkered with etc. etc. if you do not mind that 'fact' ok then, buyer be aware though.........
Also remember there is no owners manual supplied with JJ's apparently either? why not??? this is a BIG issue especially if you are a newby to turbines and not familiar with gas turbine assembly, install, set-up and operating. ECU parameters need to checked and set for reliable safe operation, these basic details are always supplied by the manufacturers in owner/operators manual.

Interestingly part of the AMA turbine approval process for turbine destruction testing requires a manfacturers turbine to be run at max RPM (JJ would be 160k) for 5 min max. From what I have seen heard and read the stock JJ 1200 will not run reliably at 160k for long if at all ....
Please prove me wrong and I will buy a JJ tomorrow.

P.S. no time for tinkering or BS ;)

[acrored]

Yeah not likely to be dangerous I would have to agree......well sort of,
As since day one 'ALL' stock JJ's as delivered do not seem to run even ok unless modified????? guys that is the bottom line simply put. The JJ does not run to factory specifications unless MODIFIED, tinkered with etc. etc. if you do not mind that 'fact' ok then, buyer be aware though.........
Also remember there is no owners manual supplied with JJ's apparently either? why not??? this is a BIG issue especially if you are a newby to turbines and not familiar with gas turbine assembly, install, set-up and operating. ECU parameters need to checked and set for reliable safe operation, these basic details are always supplied by the manufacturers in owner/operators manual.

Interestingly part of the AMA turbine approval process for turbine destruction testing requires a manfacturers turbine to be run at max RPM (JJ would be 160k) for 5 min max. From what I have seen heard and read the stock JJ 1200 will not run reliably at 160k for long if at all ....
Please prove me wrong and I will buy a JJ tomorrow.

P.S. no time for tinkering or BS ;)

My first (S/N 650 or so) JJ-1400 run at 160K for 10 minutes run after run no problem at all after I installed a new Inconel CC suplied by JetJoe and I change the first very restricted lubrication line, but newer Jetjoe engines come with that modification as stock.

[captinnitro]

It is my understanding that if you by from the US jet Joe, they stand behind them. Furthermore, you can buy an assembled turbine and even have them test them before shipped out. In my mind that’s a better rout to take and still much cheaper then the competition. I will keep a close eye on these guys. I still would love to hear from guys who bought the turbine assembled from the US distributors rather then from 3dr parties. And please don’t take me the wrong way. I am not trying to be neither ignorant nor rude in any way. I like many others would love to own turbine but are a bit out of our reach. Any alternative is well received. I have looked for used turbines and they are very hard to find. Ether they last forever or people just don’t sell them at a reasonable price.

[J Klenske]

J Klenske,
Thank you for that bit of information. Not sure what it has to do with the number of JJ's produced.
Joe

There are about 800 turbine waiver holders in the USA, and how many turbine modellers worldwide..... 3000, 4000 ??
Joe[/QUOTE]


It has nothing to do with JJ but it shows that your estimate about the total number of micro turbine jets might be low. Or it could be that there are alot of them out there that never make it to a model.

[hendrix]

Hi and first of all i want to wish you all a happy new year and good health.

I bought a jj1400 some time ago i think the s/n was 790 or something i dont remember. I asked for the engine to be tested before shipment but i can assure you that it was not tested.
I bought it assembled with full autostart and a "flight works" pump.
It never went up to 160k except from one time and always with a sky high EGT, around 720 to 800 degrees. Usualy it could do only 145K rpm and the EGT was getting up to 800C like something was holding it.
Jet joe told me to keep it running below 100Krpm for a while and after that everything will be OK.
That was the first bell i heard in my mind as i know that turbines dont want or need break in like a reciprocating engine.
Another problem was the frequent flameouts no matter what acceleration and deceleration delays i used.
I want to make sure to all that i used the best parts, Clean fuel, turbine oil, filters and procedures for testing the engine and never let it work for over a few seconds at a time since it was evident that something was wrong.
After i decided to remove the cover i inspected visualy the engine but i couldn't see anything wrong inside except from the very thin lubrication tube and a badly bent brass fuel line, still functional though.
One thing i found was that the turbine wheel had a wobble of ~1mm for and aft like the shaft hole was not 90 degrees to the turbine wheel or the wheel blades were not at the same plane.
I just looked from the side and i could clearly see the turbine blades move for and aft while rotating. I just couldn't believe it so i persuaded my self that i was seeing ghosts.
Also the clearance between the NGV wall and the turbine wheel was excessive but above all it was not equal, one side of the Ngv was closer to the wheel fins than the other indicating that the NGV was either distorted or not positioned dead center in respect with the shaft.
By that time i knew that i couldn't depend on JetJoe for a "in warranty" repair
because i realised that it was his policy to send untested low quality engines as fully working engines so i contacted someone (a friend) far better than me in order to have a look at my JJ1400.
I can't say his name but he was a Jetjoe dealer in UK sometime ago but not now.
He found that the turbine wheel was out of alighnment, the rear bearing toasted and the NGV distorted.
After replacing the NGV and the rear bearing the jj1400 still woudln't run ok.
The turbine wheel could not be rebalanced again so i had to decide if i will throw more money away or stop here.
I told him to just stop doing anything and throw the engine in the garbage bin somewhat joking and somewhat seriously as i was truly frustrated.
The following days he did exactly that :D and the mechanical parts ended up actualy in the garbage bin.
This happened due to a misunderstanding (English is not my native language)
I didn't requested any warranty repair or refund before sending the engine abroad as i was certain that i was waisting my time and money by sending the engine back to China (at least that was my impression then).
Right now i know that this was a good move as this engine needs a lot of machining experience, parts and money in order to make it work somewhat acceptable but still i wouldn't trust this turbine flying an expensive jet, not even a trainer.
After recovering from the loss of money but above all from the endless failures i had with this engine i decided not to buy anything from China again unless it is endorsed from a reputable European (since i live in EU) manufacturer.
I am not a racist but nobody can convince me that China can make something of high tech on its own or it has any credibility since they lied to me in many areas indicating a real policy and not just bad luck.
I dont blame anyone but me for making that order.
Maybe the Jetjoe turbines are mature now i just dont care any more.
I want to make clear to everyone that this is my experience only and i hope all the other Jet joe owners had better luck than me.
Maybe i am too hard on JetJoe but in my mind this particular turbine i bought should never left from the factory in the first place.
PS sorry for the long post but it is not easy to explain my experience with the JJ1400 in a few words.
Chris

[captinnitro]

Hi Hendrix, Happy New Year. First of all thank you for your sincere post. Did you buy direct from jet Joe or did you purchase it from jet Joe US. I seen there warranty and it looks good. However I do understand what you are saying. I am in the trades. We hate Chinese tools. For accurate tools we go with German, Italian, and if we are lucky enough, American. (Something that’s becoming impossible.)

[hendrix]

Hi.
Yes i bought it directly from Jetjoe, payed about 100 Euro in custom taxes
and the only thing good i got was the Nades Fadec, pump and sensors.
Even the battery was bad as it could hold only 1100 mah and not 1800 as the rated capacity was declared.
I dont know maybe the USA dealer is backing the turbines well which should be the case since USA is not China and consumer trust is high.
In my eyes the problem is poor machining, poor if at all quality control
and i suspect but cannot say for sure, recirculation of returned defective parts.
With that money i could buy now a trefz tt66 (KJ66) or a Frank or a funsonic fs70 or a RT hammer 80 turbine. All of those are very good turbines, well respected in Europe.
Chris

[joeflier]

It has nothing to do with JJ but it shows that your estimate about the total number of micro turbine jets might be low. Or it could be that there are alot of them out there that never make it to a model.

My estimate may be low. The point I wish to make is that the model turbine market is a small market and that serial numbers are not necessarily an indication of how many were produced. Your P-60- could be the 6500th turbine produced by Jetcat since the started about 10 years ago, or they might have started producing P-60's with serial number 6001. I really don't know Jetcat's or JJ's numbering scheme.

Most importantly I don't believe that JJ could have sold 2000 turbines in the past two years. I have read a lot of the JJ postings on this and other forums with interest and couriosity. I can understand a few being attracted by the low price and some by the challenge of getting one to start and run properly.

The fact is most JJ's do not run right out of the box like other manufacturers. Additionally they require major modifications and components from other manufactures to start and run properly. Those who have taken them apart report major quality issues. While a lot of Chinese manufactures are good at copying, they lack understanding of the basic technology, critical design standards, proper quality control, and proper metallurgy.

With all the effort required just to get one to start and run i have zero confidence that one would ever make it to 25 hours. It is highly unlikely that anything close to 2000 modellers would want the hassle or to risk their money on something with such a low probability of success.

Joe

[HobbyCNC]

Another JJ Happy customer! From thread on the other forum.....

I started a JJ1400 for the first time two times today, both times it started OK but during the ramp up to idle it coughed and popped quite a lot, second time it was with low light and I could see that everytime it popped a small flame got out and at one time a flame came out between the seam of the exhaust cone and the casing. Once on idle it went OK, but after the event I did not feel confident to bring it to full power. Waht could be causing this? My RAM 500 does not do this at all, could the CC be disintegrating?

Still not getting it right after "2,000" units!

Dave

[hendrix]

Still not getting it right after "2,000" units!

He probably waits until the stock runs out.
Do you think that after finding out that a part is not correct and not repairable he will thow it in the garbage or that this part will eventualy find its way in to a turbine?
Even i could build a very good turbine after 2000 tries :D
I also believe that even if someone is lucky enough to get a turbine that runs well it wont be long before the engine starts to deteriorate in an accelerating fashion (i estimate it to be about 20~30 minutes or 3 to 4 runs)
Some very lucky people might get a turbine that runs well continiously.
I must say that it is very good to see that some dealers like the USA one have decided to service and back up what they sell (jj turbines)
I remember that everytime i started the turbine it behaved differently each time.
At first it lighted up very well but could not reach 160Krpm and after a couple starts it started poping and coughing (if this is the correct word)
After that it started to flame out at approximately 90Krpm during acceleration
and after only 15 litres of fuel i decided to stop testing it.
Chris

[AirbusPilot]

He probably waits until the stock runs out.
Do you think that after finding out that a part is not correct and not repairable he will thow it in the garbage or that this part will eventualy find its way in to a turbine?
Even i could build a very good turbine after 2000 tries :D
I also believe that even if someone is lucky enough to get a turbine that runs well it wont be long before the engine starts to deteriorate in an accelerating fashion (i estimate it to be about 20~30 minutes or 3 to 4 runs)
Some very lucky people might get a turbine that runs well continiously.
I must say that it is very good to see that some dealers like the USA one have decided to service and back up what they sell (jj turbines)
I remember that everytime i started the turbine it behaved differently each time.
At first it lighted up very well but could not reach 160Krpm and after a couple starts it started poping and coughing (if this is the correct word)
After that it started to flame out at approximately 90Krpm during acceleration
and after only 15 litres of fuel i decided to stop testing it.
Chris

I think for that time that you were using the old NO Inconel Combustion Camber thats why the engine deteriorated but now JJ has new Inconel CC.

happy new year to all turbines flyers

[hendrix]

Happy new year to everyone.
Yes i had the non inconel CC, you are correct.
Chris

[jet-mad]

:) More about the Jetjoe 1200 Kit Fuel Pump: Fuel supply is, in my opinion, a critical aspect of running a model jet engine, and I give fuel pumps a high degree of attention. All the internal contact surfaces are normally machined with precision, to reduce fuel leaks during operation. However, in a new pump those rubbing surfaces are not totally and finally ‘formed’ and they need some running before they become ‘mated’ to each other. After that, it is of upmost importance that those parts are not disturbed in any way, in particular they do not move relative to each other, because if they do, the precious ‘mating’ would be lost, the leak losses increased and the fuel pressure reduced (perhaps forever!). As mentioned before, I had concerns about the pump body cover being kind of loose in this pump, and so have added 3 roll pins, to fix the position of the cover (see pic). This modification still allows the cover to be removed if necessary, for inspection, etc, but ensures it goes back to the same spot afterwards. I felt that I had to do this before any tests because it is important for an accurate evaluation of the useful life of this pump under normal conditions, so that more people can take advantage of its low cost and use it if the result is good.
After the mod, I ran the pump with the tubing loop and kero for about 10 minutes, and then checked the fuel flow rate and pressure; during the run, very fine metal swarf appears inside the clear plastic tubing, which of course must be cleaned a few times until it runs clear.
I’ve also finished the changes to the electronic speed control for the pump that now allows precise control of the pump flow rate.
I then proceeded to measure the max Pressures with a digital manometer calibrated in Bar (1bar=approx. 1Kg/cm2=approx. 14.5 pound/sq.inch) and the max. Flow Rates with a chronometer, an empty cylindrical metal can and a metal ruler. This is what I measured:

Supply Voltage (V) --- Max. Flow Rate (ml/min) --- Max. Pressure (Bar)
1.0------------------------69.3------------------------0.14
1.5-----------------------134.7------------------------0.36
2.0-----------------------184.8------------------------0.59
3.0-----------------------300.2------------------------1.24
4.0-----------------------412.7------------------------1.95

From the figures above I’d say this pump would be OK for the engine, considering that the Flow Rate will drop somewhat, at the working pressures.

For those interested, this is what I did: I first scratch-marked the motor/pump body/cover, to maintain their original relative positions throughout the procedure. The 3 pins are 1/16” dia. x about ¼” long (because I happened to have some in my junk box but any other similar diameter is ok, and 2 pins would probably be enough). After marking the positions for the 3 holes (not very critical, but make sure the holes are well clear of any other internal parts of the pump) and tightening well the pump cover screws (make sure the cover is perfectly centred on the body), I first drilled with a 1mm drill to about 7mm deep. Then enlarged the holes with a 1.6mm drill. Then cleaned the swarf very well and removed the cover. Then inserted the 3 pins into the pump body holes (I found necessary (with a small hammer) to very lightly and carefully hammer the pins in, while holding the pump in one hand...do not miss!!!). I then enlarged the holes in the cover with a 1.7mm drill; this provides a light-push fit for the cover, also allowing its removal if necessary, the pins remaining in the pump’s body, permanently. I added 2 wave washers to the holding screws, and after thoroughly cleaning and re-assembling the pump, I re-connected the tubing loop, filling it with kero and a few drops of motor oil. I then ran the pump with 2 volts, carefully adjusting the 2 holding screws and carefully moving the pump body re the motor, for the lowest current and the smoothest running. At that point, I stopped the pump and without moving anything, secured the position of the (well cleaned with Metho) pump body to the motor (not the cover!) with cyano glue along the joint.

I’m now looking at the bearings and at the rpm counter. I’ve ordered a few parts and all should be ready shortly, for the test run. See you soon. Richard.

[lazy-b]

Guys: its our fist time to setup and Run a JETJOE 1400 TURBINE ENGINE in the Philippines.....the jetjoe engine is own by Christian Chua, and its was setup on the engine test stand by JET ACUNA, with ERWIN FELISARTA and me Ellion Cham taking the Video documentation.

there has been a wrong wiring on the FADER units, the Wiring on the NEGATIVE WIRE of GLOW PLUG and NEGATIVE WIRE of the FUEL PUMP is INTERCHANGE, we just cut the 2 wiring and interchange it.......Upon initial Test Run, it say Glow Disconnected, we found out a defective Brand New GLOW PLUG.

Initially, its quite difficult to start the engine, cause we do not have a PROPANE Gas Regulor, we just use a COLEMAN POWERMAX BUTANE and transfer its Butane gas into a small CANNISTER (come with the packages) and use a small silicon tubing (we just clip the tubing to prevent gas from excaping).......upon start it just make a small PUFF sound, I guess all Butane gas is all used up.

Next, we use a SMALL BUTANE TORCH (Pencil size).....this is much easier to control the flow of Butane gas to the engine.

Its Really AMAZING able to SEE & HEAR a REAL JET ENGINE WORKS

Here its video:

http://www.youtube.com/watch?v=Zhva5cN1K7g

Here is the 2nd Run:
Have prematurely shut-off the the engine due to loose in Jet Engine Holder, maybe due to heat the holder get loose.


http://www.youtube.com/watch?v=kjPKmnzK4NM

Here is the 3rd Run:

http://www.youtube.com/watch?v=5Cc9A2whysg

[Graeme Marion]

Congratulations.
Thanks for posting the videos.
Now install it in a model and go flying.