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Old Jan 01, 2013, 10:46 AM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
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with regards to your field length.. Any Boomerang jet will land with in 200' or less when you get used to it. They can take off in about 75' on grass, with a P80

Because they are not scale jets..They can incorporate all the GOOD stuff that make a plane fly well. Believe me..So much of your attention will be on the turbine its self in the beginning... that you dont need to be detracted by a demanding air frame.

Learn to fly jets first! Then sell it and get what you want. There's no more Instant power. Turbine lag will be an entirely new experience to you.
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Old Jan 04, 2013, 07:33 PM
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Wise words...

Quote:
Originally Posted by Dr Honda View Post
...what you need to do is go to a jet rally that is local to you, and talk to they guys, and watch how different models land....
Dr. Honda has wise words here. I went to three jet rally's as a spectator before I decided on my first jet turbine model. Even if you can easily afford a jet it is a sizeable investment and a big responsibility. Each of our experiences are different and will require different "training" to make sure we are safe with these turbine jets. While you're thinking about it fly a generation two Park Zone Habu

I ended up buying a ready to fly turbine jet from a respected modeler who knows what he's doing so I could learn first hand what a solid set up looks like and how it operates.

Good luck with your decision.
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Old Jan 06, 2013, 01:59 PM
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Well Dr Honda, that was one great post with lots of good info in it and I understand where you are coming from and appreciate the input. With more thinking on this, I am moving away from the F-15... even the lightest one would be a nearly 30lb airplane... the fuel consumption and hence model weight in this class is significant. While I would still prefer a military jet, I hear what you (and Vettster)are saying about the used trainer and am open to the idea. For scale jets, the biggest that I would want / manage would be something in the 16lb class like a Global Jet F-16 with the JC Bee - halfway to Henke's approach. I've done some wing area calculations and wing loading appears reasonable at 31oz in that weight range.

Regarding my field, it is in a flood control area so the airspace is wide-open 360 with no houses for at least 2 miles in any direction. The approach path is completely clear as far as vision goes, so there is zero pucker factor there.The only way one of my planes of any size could hit a house, land on a road etc would be if I lost radio and it flew away on me. I am very safety conscious ( I refuse to fly park flyers in parks) and would never attempt to operate any model, let alone a turbine, if there was danger to others.

All this said, I am not a foolhardy person, and I am very careful in how I spend my money. So I am not about to go out, buy something and try to fly it. As you guys suggested, the first thing I will do is go to a jet rally or a field active in turbines so I can see first hand how these fly, whether I have the skills/vision for this. Scott from Globaljet has already offered me to come to his hoime field and see how it is done. If all that checks out, then the turbine waiver will be next. After that we'll see.

Vettster - can you elaborate a bit on turbine challenges themselves? I understand I need to know startups (hotstarts etc) and sfaety, but do these require a lot of additional fiddling? How common are flame-outs? BTW, I love that Avonds F-104. I hope you got it sorted out handling wise.

Henke - that is a great video and some excellent piloting skills as well. In fact, one thing that strikes me about these jet vidoes is that you guys are really good pilots and your approaches landings are extremely good. If you are nervous on the sticks - you're not showing it. I on the other hand am still at the stage where nerves get the better of me at times. I can say that your venom would be a handful for me, or at least I'd have to be on the lowest throttle setting.

Flying Tiger - I also think a fast big EDF is a good interim step. The Habu is a nice plane but would I be better served with a tougher landing jet like the Efite Fhantom to at least learn energy management? Just wondering.

In any case, thank you very much for all the replies - all are appreciated. I did not mean to come off as know-it all - my writing style can give that impression sometimes - I am far from that and I do listen, so your advice is not wasted.
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Old Jan 06, 2013, 04:34 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
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Quote:
Originally Posted by TTRotary View Post

Vettster - can you elaborate a bit on turbine challenges themselves? I understand I need to know startups (hotstarts etc) and sfaety, but do these require a lot of additional fiddling? How common are flame-outs? BTW, I love that Avonds F-104. I hope you got it sorted out handling wise.
I dont know if there are Challenges with regards to turbines.. Its just that its a totally different experience. Newer turbines dont have as much turbine lag as older ones. I have a RAM750 and once you hit zero on the throttle stick, it takes 6 seconds to get to full throttle. Now think of that when you balk a landing and your very slow with gear down and flaps down and the plane weighs 25lbs. But that will not be the case as I would assume that you are going to buy a newer model of engine. Todays engines have a much faster spool up time. Maybe 2 seconds from 0 to full throttle. But still there is a bit of lag at the bottom end. 1/3 to full throttle now aways is hardly even noticeable. All I was really saying is that if you fly a gasser or an EDF and you need that little burp of throttle to help you on final...Its just not there as instantly as you may be used to. Rookies tend to look for that instant power, and when it doesnt come, they add more throttle,.. whell before you know it the turbine has spooled up and your coming in hot. From your replies I dont think you would have any trouble at all. But still every thing i just mentioned means your attention will be on the engine and not the plane as much. Combine this with a warbird that has heavy wing loading and gear doors etc all to worry about as you make your approach and it can be over whelming.

Flame outs are not that common but the DO happen. They can always be tracked down to one thing or another. I have an Angel jet with a Jetcat Titan(35lbs)that has had over 50 flights on it without issue. I was at an event last fall and I had landed and fueled up, and was out to go again. I was on the runway..went to full throttle as usual and just as the plane lifted off the engine quit. Not good! No air speed, full of fuel, bad angle of attack. Needless to say she bounced. Why all of a sudden did it decide not to work? I had purchased the plane used and RTF. The original owner had used Festo fitting coming out of the UAT. I now know that this is a mistake. They work fine for awhile.. but then the tygon changes shape and thus changes the shape of the o-ring in the festo fitting allowing air to be sucked in only at full throttle. The second thing I learned was not to use tygon between the UAT and the Fuel pump as it will collapse on the suction side.

There are many many reasons for flame outs. Low batteries, Old fuel pump, Clunk get stuck.. Its up to the builder to learn as much as he can during the installation and not to be afraid to ask questions.

I hope Im not scaring you too much lol. There's really nothing to them once you have the knowledge. You will enjoy flying a turbine more than any other plane you have ever flown.

You wont fully understand what I mean by having all your attention on the engine until the day you go to maiden your new plane. Its then that you will be greatful that you purchased a trainer As I was once told.. "once you forget there;s a turbine on the back..then you will start having fun"

Good luck with what ever you choose. Keep us in the loop.

ps: thanks for your comment on the F-104.. she;s good to go for next season
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Old Jan 06, 2013, 07:45 PM
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A lot of good information has been provided already, so I will simply emphasize attending some jet events that are relatively close to you and talk with some of the participants is definitely a good starting point. Take a look at some of the planes being flown, specifically take off and landing speed and the amount of runway used for both. I personally found doing this really alleviated a lot of the guest work for me when it came to selecting the airframe that would fit my particular needs and interest.

Like you, I to was not very interested in the non scale planes like the Boomerang, Shokjet, etc. However, since I had previous flown ducted fans, I had a couple of scale jets (F-16, F-18, AJ37 Vig, etc) that I converted as my fly turbine-powered models. I was able to cut the intial cost of my introduction to turbine, because I only needed the engine and some support equipment (fire extinguisher, etc). I did however find that scale jets tend to be less forgiving and more costly is the long run for everyday flying. So if I were to suggest a particular airframe for someone interested in flying alot, those airframe would be the Boomerang, Shokjet, and perhaps the Turbinator. With the exception of the Boomerang (size dependent), you could actually stay within the $4000 price range.

Good luck with your decision.
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Old Jan 06, 2013, 09:03 PM
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Quote:
Originally Posted by Vantagepoint View Post
....... I did however find that scale jets tend to be less forgiving and more costly is the long run for everyday flying. .................
That's also a good point.

I'm not a typical "Jet Jock" at all... but I love the sound, and smell of my turbines. So... I just bought a Shock jet as my "beater" or "Every day" jet, because I just joined a club with a short grass field. Yes... it's ugly... and yes... it supposed to be a trainer... but it's a jet you can fly without worry.

With that said... It's going to get a 22 Lb thrust Jet Central Falcon turbine. (it was designed for 15 Lbs)

Anyway... what I'm saying is... get your trainer... and your warbird. Depending on your local field... you may find that you fly the "Sport" model more than you thought you would.
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Old Jan 07, 2013, 02:15 AM
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Quote:
Originally Posted by Dr Honda View Post
I never responded (originally) because you have the wrong attitude. Since you fly RC already... you should understand the importance of a trainer.

As others have said... you need to start with a "Trainer". If you are a good pilot... jet's aren't any harder than any other model to fly... but you need to learn how to handle them.

Go buy a used trainer... fly it... get your waiver... then sell it for the same $$$ you paid for it.

As an FYI... most warbirds will land fast and heavy, despite what others say.

If you don't like my answer... then what you need to do is go to a jet rally that is local to you, and talk to they guys, and watch how different models land. Everyone has a different opinion here... but the only "Military jet" that I think a good pilot could start with is an F-16, or any "Military" trainer. (Like an L-59/39) I know guys say that an F-15 will land easy, but I've seen more of them damaged on landings than any other military type jet.


Finally... the 500' runway all depends on what the overfly areas look like. If it's wide open on either end... and you can use the entire runway... it's not a problem. If there are tall trees, or other things to crash into... then it's small.

Here's the deal... as you are aware... a turbine at idle is still producing high velocity thrust. A "slippery" model will pick up speed fast, if you need to put the nose down to clear trees, and then hit a runway. With a jet... flaps, and nose high attitude helps keep the speed in check... but that leaves you using the engine to control decent. BUT... since the throttle lag at idle is so long... a newb will wind up crushing the landing. A trainer will allow you to learn throttle management, and how to bleed off speed properly.

When you are flying your prop warbirds... the prop, at idle, is actually acting like a brake. The air velocity is low, and the "Disk" of the prop is high drag. So... if you are using a lot of runway now... you will overshoot with a jet. (and that's why a trainer is good)

I'm not trying to be harsh... but I see it all the time... guys try to not use trainers, and they wind up spending a lot of $$$ just to crash.
Very good post you should listen and heed what has been said
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Old Jan 07, 2013, 09:31 AM
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Just to give a different viewpoint -

My first jet was an F-86 Sabre, Trim kit, weight about 22lbs at take off, 12lbs thrust, 270ft tarmac runway with rough run off at each end. It's still flying today 9 years later, with over 500 flights and more than 6,000 miles on the clock (GPS logger says so!) Upgraded it to 14lbs and then 18lbs of thrust over the years.
See http://frettavefur.net/video/mpx/ for videos of my first ever jet take off and landing, with it.

Second jet was an Avonds F-104 but from a much longer runway!

So a first jet can be scale, can be swept wing, can be operated from a short runway IF you really can fly proper, accurate, consistent approaches and not do the usual model flier approach of throttle to idle and stick the nose down and dive at a steep angle with far too much speed, you do need to be able to fly a shallow, power on, attitude controlled approach.

H
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Old Jan 07, 2013, 12:37 PM
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[QUOTE=vettster;23732322]There are many many reasons for flame outs. Low batteries, Old fuel pump, Clunk get stuck.. Its up to the builder to learn as much as he can during the installation and not to be afraid to ask questions.

I hope Im not scaring you too much lol. QUOTE]

Thanks Vettster - did not quote everything to save space but it is all taken in. A fuel-powered engine would definitely be a whole new world to me. I've never flown even nitro or gas. That would seem to be even more reason to buy a built up jet from a reputable modeler that is set up right, so I can see what that looks like. Then again, you never know when you are getting someone else's problem. My question is - which way is better? I assume most of the engines sold today are pretty complete, and I would definitely want the newer more responsive designs. So should I buy, let's say, a new Bee II and get it running and learn it, or should I go for a complete trainer?

And not, you're not scaring me. I'm a tinkerer and way too stubborn anyway!
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Old Jan 07, 2013, 01:57 PM
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Just as a suggestion, if you don't want to have multiple turbines in your inventory, consider purchasing a medium thrust unit. I would suggest a turbine with a minimum of 22-28 lbs of thrust. There is a good selection of airframe available for turbine with this thrust rating. Also, if you are serious about turbine powered-models, bite the bullet and get a unit that has been around for awhile and is known for having good service support. I would personally steer away from anything that has just been released from company new on the scene.
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Old Jan 07, 2013, 04:36 PM
"Take Off" eh!
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As Vantage says.. stick with a company that has been around for a while. JetCat for example. Kingtech is about 5 years old now but still has earned a good name.

This is just an example of a VERY sweet deal and is active now! http://www.rcuniverse.com/market/item.cfm?itemId=891397
I have this engine and it runs flawlessly. 22lbs of thrust and very responsive.
Any Jetcat with SE on the end is the new more powerfull and consumes less fuel. Non SE's are old teck, but still have a place in the hobby, plus cost less.

Here's an example of the type of plane that "I" recommend. Others opinions may vary..
http://www.rcuniverse.com/market/item.cfm?itemId=892240
As a curticy to the person selling this jet(I dont know him) I wont comment other than to say that the engine is a tad small. Pm me if you would like to discuss it more.

Trevor
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Old Jan 07, 2013, 08:41 PM
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Thx Trevor. Thanks to you, I'm trolling that section every day to get an idea of prices. I know this is for example only, but I might stay away from this particular one though, as I've read that the P-70 is a bit of a dog among modern turbines with especially slow spooling. I saw some nice-looking boomerangs complete for $3K the other day.
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Old Jan 07, 2013, 08:45 PM
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Just another point to consider when buying from the RCU Marketplace, always check the seller's rating, the date he joined RCU, and read some of the feedback buyers from that particular individual may have written. Unless a person is highly recommended by someone well-known in the hobby, steer clear of anyone who has just recently joined (couple of months as member) RCU. I am sure you know this, but don't hesitate to ask for more detail pictures of the model being considered (pictures from all angles including the some internal shots of the airframe).
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Old Jan 07, 2013, 08:57 PM
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Quote:
Originally Posted by TTRotary View Post
Thx Trevor. Thanks to you, I'm trolling that section every day to get an idea of prices. I know this is for example only, but I might stay away from this particular one though, as I've read that the P-70 is a bit of a dog among modern turbines with especially slow spooling. I saw some nice-looking boomerangs complete for $3K the other day.
Yes... P-70's are some very slow spooling turbines... but they were a good solid engine. I hear people joking about starting them, pushing up the throttle... going to get a drink... and then coming back... and the turbine is just coming up. (lol) But realistically... I think I've heard 6 to 10 seconds from idle to full. (very slow) But... when you are flying... if you keep it above 1/4 throttle... the response to full is only around 3 seconds. (not too bad)

One thing to remember... with a turbine, the thrust isn't linear, as with a prop engine. Turbine thrust is exponential. So... 1/4 throttle, is only about 1/10th the thrust. (not too bad)

The newer Jet cat engines are around 3 seconds. (idle to full)
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Old Jan 08, 2013, 03:05 AM
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WHOA!

Quote:
Originally Posted by TTRotary View Post
I have moderate flying skills at this point and am focused on .60-.120 size warbirds. I am at the point where I can land these pretty consistently and can manage fairly high wing loadings, retracts, flaps, etc. .
Quote:
Originally Posted by TTRotary View Post
A fuel-powered engine would definitely be a whole new world to me. I've never flown even nitro or gas.
So which one is true TTRotary?
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