Chris Golds F-4J Tomcatter Phantom [Archive]

Robert May

Jul 04, 2006, 03:27 AM

Here is a sneak preview of Chris's latest project, An F-4J Phantom of VF31 Tomcatters.

This is a 30" span bungee model with twin Vasa55 fans, Hacker B20-12 and Flightpower 3s2p 5000mah Lipo.

The model is fantastically simple for a twin EDF model and I have been staggered just how quickly it is coming together. We are hoping to maiden before my Australia trip in 2 weeks time.

Finished Photos post 26, Flying shots post 50

Synwpn

Jul 04, 2006, 04:22 AM

Incredible! Another wonder from Chris Gold. Thank you for the peek Robert! I definitely will need to build this one! Will the plans appear in QEFI?

Sluf7

Jul 04, 2006, 04:59 AM

Does that man never Sleep. Must be the Tea dunked Coc Bickie's.:0)

Nice job as always.:0)

Ah so ya going to the Lucky country eh. Don't forget ya snake & Spider bite kit also a good Croc repellor is a good Idea & watch those Bloody Kangaroo's Rob they can really kick.

Robert May

Jul 04, 2006, 05:49 AM

Thanks guys

Chris is in his workshop at 6am, 4 days a week in the summer, 5 in winter. He has finally admitted that he is addicted to designing and building.

On a technical note does anyone know if there is a problem "Y" leading two BEC Kontronic speed controllers and feeding both ESCs from one pack? We are wondering if we need to run a separate receiver battery.

I am looking forward to the Oz trip, I have heard that it is a fantastic place and the folks are real nice.

dave morris

Jul 04, 2006, 08:02 AM

Robert May

Jul 04, 2006, 08:21 AM

are you using heat sinks on the hackers?

The reason I ask is I overheated that same setup with older tech Lipos, My guess is with the better lipos today you may risk overheating and demaging the motors with out a heat sink.

Don't know about the Kontronic BEC's I just read on the castle forum that the becs on the castle ESC's can be run together as you described. Perhaps a post on the kontronic forum would be in order.

Nice looking project

Thanks Dave

The Phantom offers a lot of good modeling points I am surprised that it is not modelled more often. There are some fantastic colour scheme, almost too many to choose from.

:eek: There no heatsinks on the Hackers and the model has been built around them. We are using the Flightpower Carbons, not the latest technology so we might get away with it!?
Ron is getting some heatsinks made up for the ESCs, those will protude into the inlet ducts.

We are aiming for 45-50oz on a flat plate wing of about 1.8sqft so this is not going to be a ballistic model. A bungee launch and nice simple ducts should mean it is capable of flight. Fingers crossed!

Alex says that Haldor will probably have the definitive answer on the BEC issue, it will be nice if we can make do without anther ounce or so of ballast

dave morris

Jul 04, 2006, 08:34 AM

I was fine until one extended full power run (prob 2 min wide open) that plus our hi ambiant heat here in central Florida, was more than the poor hackers could take. Some very bright folks did a lot of math some time ago on my situation and explained it very well.

Your best bet will be to limit the full power runs to short burst with plenty of low power in between, Or fly in the cool months of the year. I was able to check the temps of the motor using a IR temp prob gun.

If you later decide to do the same setup you may check into a heat sink that I think is carried by Maxx products. It fits the 20mm motor and with little or no machining should be adaptable to the vasa motor tube. The heat sink works very well, I do not know why more people dont use them, esp the very high power guys that keep melting motors. Think of it like running a two stroke glow engine with no cooling fins.

Robert May

Jul 04, 2006, 09:14 AM

We don't get too may days here in Devon that most folk would call hot! 25-26 degrees C is a max. The sea breeze comes in about 11:00 and keeps us cooled down.

I will mention adding heatsinks before we go much further. Corrugating some Litho plate and attaching with heat transfer epoxy should be a very easy and quick precaution. We might find that we don't have the luxury of partial throttle given the size and weight of the model

dave morris

Jul 04, 2006, 09:36 AM

That sounds nice, it will be around 32-35c here today with 90% humidity most likely. Best of luck with the project.

tow

Jul 04, 2006, 11:20 AM

On a technical note does anyone know if there is a problem "Y" leading two BEC Kontronic speed controllers and feeding both ESCs from one pack? We are wondering if we need to run a separate receiver battery.

Far as I know, the "Jazz" series Kontronik Controllers allowes you to run two from one battery with the Bec enabled. You can always disconnect the + on one of them just to be sure nothing bad happens.

Ed Waldrep

Jul 04, 2006, 11:54 AM

I ran two Kontronic Smile 40-6-12s with both BECs enabled on my own design A-10 and then my scratchbuilt F-22 for probably 60 flights total and never had a problem with th ebec. I was running 8000 mah packs so I never really came close to running low on voltage and having the motor cutoff activate. I did have thermal shutdowns in the A-10 though with no heat sink (one controller in that one was a 30-6-12) but as far as BEC goes no issue. Both controllers were feeding off of one large 8000 mah pack.

Robert May

Jul 04, 2006, 12:16 PM

Thanks Ed

Dave, I have just spoken to Chris, it is too late to do a proper job of adding heat sinks to the motors. We will have to see if we have the same problem.

Haldor

Jul 05, 2006, 07:13 AM

BEC enabled on both Kontornik ESC's are not an issue, just use an Y-lead as mentioned and go fly.

The possible problem with 2BEC's Y-d together is if one is outputting more voltage than the other = the lower BEC is causing a load on the stronger one.

The BEC's in question are tight in specs and therefore this issue isnt of consern.

Robert May

Jul 05, 2006, 12:11 PM

Thank you Haldor.

We like had a feeling we would be OK but like to check these things out rather than blow 2 ESCs and a receiver.

Robert May

Jul 08, 2006, 04:29 PM

More progress

My practical contribution, a set of Decals, This will be vinyl printed and simply rubbed onto the painted model.

If I am going to be glued to a computer I might as well do something constructive

Final versions now posted to the Decal thread in "Scale"

Robert May

Jul 08, 2006, 04:56 PM

I spent a couple of hours with Chris today finalising the installation and setting up the radio ready for a maiden next weekend (weather permitting)

I also got an excuse to try my new Canon lens 70-200 F.4 L, Next investment a wide angle lens and a tripod

Gordon

Jul 10, 2006, 04:07 PM

Hi Rob

Looks like the 99 Phantom books I lent you finally came in handy.

I thought this was gonna be your project :confused:

Gordon

Robert May

Jul 10, 2006, 05:17 PM

It was Gordon, the retracts are finished and this drawing had been sitting on my board for 5 months!, Chris popped in to collect the flash card of Hunter photos and was looking something to feed his addiction for building. My work schedule means that it will be September before I can pick up a scalpel to start cutting balsa.

We decided not to use the retracts as we didn't think the Vasa/Hacker combo would deliver enough push for a 55oz model (estimated weight with retracts fitted). The motor runs so far seem to indicate thate they are throwing out more than the accepted 12-15oz thrust. With luck Friday PM will answer that question.

The Phantom is one model Chris has never modelled although he did the paint job on the Molmark Phantom several years back.

Your reference library of Phantom books has certainly been interesting to read through and a great souce of inspiration, Thank you. Lets see if we can get a squadron of small EDFs in the Chivenor skies before we lose this fantastic sunny weather.

hammo6

Jul 10, 2006, 08:57 PM

Good luck on Friday. Love the Phantom can't wait to see the video and the plan for this one.

David

Gordon

Jul 11, 2006, 01:31 AM

Don't forget ya snake & Spider bite kit also a good Croc repellor is a good Idea & watch those Bloody Kangaroo's Rob they can really kick.

Hi Rob

If you haven't read it, get hold of Bill Bryson's book. It's a great read, and he says there are more ways to meet your death from the flora and fauna in Australia than in any other country in the world :D

Enjoy!! ;)

Gordon

Gordon

Jul 11, 2006, 01:38 AM

Lets see if we can get a squadron of small EDFs in the Chivenor skies before we lose this fantastic sunny weather.

Good idea :cool: Don't forget to bring your Bantam along!

Metcheck.com has the weather looking good for Friday pm. Have they finished cutting the grass while I've be away?

Gordon

Robert May

Jul 11, 2006, 04:37 AM

They have finished the grass Gordon but its not up to their usual standard. We have a fairly course stubble to land in. The southern site looks best.

I think the best way to die in Oz is the McGuigan Vinus Juicus, Bin 2000 Shiraz or Black Label Chardonnay. No wonder the French are having to turn their fine wines into surgical spirit.

stumax

Jul 11, 2006, 06:24 PM

I am looking forward to the Oz trip, I have heard that it is a fantastic place and the folks are real nice.

Can't argue with that! You'll have to drop in and learn how to say "G'day!". Where do you plan to go?

Gordon, I think it's time you paid Oz a visit - lotsa cool stuff to see!

Great build, BTW, I wonder if it would scale up well? I'm a little concerned about the effect of the heatsink on the inlets. I think feeding them from a NACA style inlet buried in the inlets may have been cleaner, so that the air off them doesn't go into the fans.

Stu.

flying-inspecto

Jul 11, 2006, 07:12 PM

Robert May: Due have any plans available for the F-4 or know where I may get them. I worked I worked on all of the Navy and Air Force including the development of the F-4E and the British F-4K amd F-4M models at the factory here in St. Louis. Your build is fantastic and I can hardly wait for the maiden flight. Good luck with the maiden.

Cecil

Robert May

Jul 12, 2006, 06:14 AM

Can't argue with that! You'll have to drop in and learn how to say "G'day!". Where do you plan to go?

Stu.

We're going Walkabout! Sydney (Coogee and Surrey Hills), then Port Douglas via Whoop Whoop! My boss is Australian, he lives out at Mittagong and we have friends at Coolum so I am hoping that I won't have too many proplems with the lingo. I hope tadoo good.

Cecil, Plans will be published in Q&EFI (traplet publication)in 3 months or so, if it flies!

Robert May

Jul 14, 2006, 08:19 AM

Awaiting deployment, 23 days of drawing, building and decorating! AUW 48oz

like2fly!

Jul 14, 2006, 08:24 AM

WOW Robert! Mighty Fine Job you guys have done! Looks Brilliant!!

so much for bungee huh!

Sweet!! :D

Alex

Ron Laden

Jul 14, 2006, 08:36 AM

Fantastic Robert it looks great, see you at 4 pm for the maiden, I will bring along the Typhoon, maybe a two ship flyby ;)

Cheers
Ron

Robert May

Jul 14, 2006, 08:37 AM

It still is bungee, the wheels are just there for the photographs but depending on performance I might retro fit the sub micro air retracts I built during the winter. 70 grams for the set with wheels

Robert May

Jul 14, 2006, 08:42 AM

Fantastic Robert it looks great, see you at 4 pm for the maiden, I will bring along the Typhoon, maybe a two ship flyby ;)

Cheers
Ron

... Gordon will be there too with his little Lightning which is roughly the same scale. You "minfan" boys might have to be patient, this old truck has a full compliment of stores (flight one at least) and a pair of 55's. I don't think we will be setting the sky alight like you two

gerg

Jul 14, 2006, 09:27 AM

Absolutly magnificant. It's about time someone made a good model of the best jet fighter ever. So any plans for this beauty on the horizon?

Robert May

Jul 14, 2006, 09:46 AM

Chris is writing up building notes and sending plans to Traplet publications' Q&EFI, for publications in a couple of months time.

Eddie P

Jul 14, 2006, 10:52 AM

Nice work guys. It looks beautiful!

gerg

Jul 14, 2006, 12:54 PM

Beauty. I can't hardly wait.

Robert May

Jul 14, 2006, 01:31 PM

:(

Either through miscalculation or the pack deciding it prefered sitting in economy we ended up with a rearward CG. Chris made for the Keilkraft grass but spot landed on the tarmac. He has taken a badly broken model home to mend. We will try again in a month when I get back.

BTW, PPM JR 700 receivers do not like twin BEC operation, we changed it for a spare spcm one and it was fine

unclecrash

Jul 14, 2006, 06:52 PM

Sorry to hear about the wild ride. I was hoping this would go off without a hitch Im sure Chris will figure her out I am thinking seriously about building this plane when the plans come out. I had a JR 601 in my CASA Aviojet and it didnt like working in this setup. so I swapped it out and the problems went away. Dave

Robert May

Jul 15, 2006, 04:54 AM

I have just seen a video Gordon took, definitely rearward CG. Chris says the battery stop is still intact so it was a mis-calculation. This is the second Phantom I have seen where the calculated CG has been too rearward. I wonder what extra factor we need to be considering. Anhedral tail? big bulky fuselage? I don't know.

Chris has been up since 5am and has the model back in one piece, there is a chance of a flight Monday evening once the PVA has had time to dry properly.

Are you going to post the video Gordon?

stumax

Jul 15, 2006, 06:41 AM

Real bummer! Such a shame as the model looks super, as you'd expect from Chris. I'd be cautious about the rearward CG theory with an F4. Was the power on during launch? If so, and it pitched up violently, I'd be looking at the thrustline. The efflux blows directly under the tail, which will cause a low pressure region under it and cause the nose to pitch up. this effect will be greater when airspeed is low and thrust is high. Also, the efflux cones seem to point straight, whereas they should angle down slightly so that the thrust passes slightly over the 3D CG position. Steve Neil had this problem with his big Huck and Me1101. Good luck for the next try!

stu.

pontious

Jul 15, 2006, 06:41 AM

Shame it didn`t work out the first try lads, but I`m sure the Devon crew will sort it out.These little blips are sent to try us & makes eventual success all the more rewarding.Good luck lads & I`ll burn a candle to the `E` gods tonight.
Its a great model so keep trying.
Terry.

stumax

Jul 15, 2006, 06:49 AM

BTW, Robert, you'll love Coogee (the coast walk from Coogee to Bondi & back, with the obligatory ice cream in Bondi & fish'n'chips in Coogee is superb on a nice day), be careful in Surrey Hills (it's inner city and full of unsavoury types), Port Douglas is extra super, Mittagong is freezing right now (perfect to cure any homesickness!) and whoop whoop is the coolest place when you find it!

Stu.

wimpy

Jul 15, 2006, 04:11 PM

robert,

is there a chance that chris design it for 2x90mm fans that will be nice:-) :)

Robert May

Jul 15, 2006, 04:41 PM

robert,

is there a chance that chris design it for 2x90mm fans that will be nice:-) :)

I suggested a twin DS-31 and was told that would be too much work. A nice project for someone though!

Well I have just got back from the workshop where Chris and I investigated a lack of push from the back end. I don't know who told me the Hackers would draw 15amps but the actual figures we recorded was 27amps (each) and 270 Watts :eek: We think the lack of push was all the high alpha (angle of attack) the model went though during it wild ride.

I think Gordon must be struggling to edit the cussing out of his video. It was certianly useful for us to see that the ailerons were too powerful. Chris was too busy with the pitch changes to note the aileron throws.

So 540watts on a 3lb model= 180 watts/lb this is Gordon and Ron territory. If Chris had known this at the start this model would have been at least 50" span and weighed in around 5lbs with drag chute, flaps and retracts.

We have also realised that the Flightpower Carbons 5000mAh we are running are only 10.5C, so 52.5 amp continuous is a bit close for safe comfort.

I left Chris with the task of installing a twin pack of 20C 1800 mAh. The model is back in one piece and would fly tomorrow if Chris weren't off to Dorset to judge a Scale competition.

We are hoping to fly Monday evening if the weather holds.

JetPlaneFlyer

Jul 15, 2006, 05:31 PM

I met up with a retired Phantom pilot at a model flying meet last year... He was an incredibly interesting guy having flown everything from Hunters to Tornados and actually been involved in 'action' in a few of them.. He would have flown the Eurofighter Typhoon too if it had been delivered on time :rolleyes: ...

He had a lot of hours on Phantoms, he said that aerodynamically it was a nightmare and the fact that it flew at all was a triumph of thrust over aerodynamics (his words)... Maybe the model is displaying some of the full size characteristics ;) . I hope you get it sorted out.

monkamarm2000

Jul 16, 2006, 02:12 AM

I went the same path as Stu, I have seen 2 F-4's that had up thrust issues, 1 was mine the other was not. I also did a micro jaguar that had the same problem but it was after the F-4 so i was prepared and was only a few degrees off on that one.

Barry

Gordon

Jul 16, 2006, 05:06 AM

I don't know what the thrustline setup is, but Stu and Barry could be right, though the CG clearly was not where it should have been.

The pic below from Rob's first post seems to show a bit of downthrust on the tailpipes:

Here's the family version of the vid ;)

Edit 25 July: Sorry guys, I've had to dump the vid to make space in my 50Mb video upload allocation for newer material.

Gordon

JetPlaneFlyer

Jul 16, 2006, 07:22 AM

How unlucky was that :( ... Anywhere else and it would have came to earth in the long grass but it had to hit the tarmac... What is known as 'sods law' I guess.

It looked like a reaward CG to me.

Robert May

Jul 16, 2006, 06:37 PM

Thanks for sharing that Gordon, Filming the flight is certainly a great help with the debrief.

I bet you are pleased with the results from that Camera. I will have to take some video of you models when I get back.

corsair nut

Jul 16, 2006, 09:22 PM

i had a cg issue where it would go straight up then strait down, lukily, i put it in some really tall weeds with out hurting it...thats too bad, what a great looking phantom! i hope you can fix it!

Sluf7

Jul 16, 2006, 09:50 PM

Bummer

Robert May

Jul 17, 2006, 04:49 PM

These say it all,

CG has been moved 1.25" forward and this model now flies fantastically!!!! :D

We are now a little nose heavy but that can be easily sorted out now we have tamed the beast.

The UK guys can see the Phantom at Colerne but Chris will not be flying it there. But you can look forward to the Hunter.

Now I have posted this I had better go and pack.

Chris was cruising at 50% throttle. ( I have programmed a linear throttle curve into the transmitter) once I am back I will post what the cruising draw is.

Kevin Cox

Jul 17, 2006, 04:53 PM

Tell Chris congrats!

Sluf7

Jul 17, 2006, 08:26 PM

Nice job and I always like the way Chris has Stores of Weapons on his Machines as they look naked other wise.

Jolly good Show Lads Well done Toodle Pip then Ole Bean.

pontious

Jul 18, 2006, 04:18 AM

Many congrats, I knew you would get there.
We have been grass cutting at Colerne last week with another final cut scheduled for this Thurs. Looking forward to seing the Phantom & Hunter there. I shall be taking my Lightning & Vulcan so the R.A.F. will be well represented.Fingers crossed for good weather.
Terry.

like2fly!

Jul 18, 2006, 04:56 AM

very! :cool:

:D

dave morris

Jul 18, 2006, 09:06 AM

Very nice, looking forward to the video. FYI 15amps on a 3s pack sounds about right for a 50mm micro fan, no overheating problems. the 270 watts sounds about right for the VASA 55mm fan, I think I was a little higher than that, not sure, type of pack and voltage suppression plays into the calc. That is why I was concerned about your setup with no heat sinks. If you can restrain yourself you should be ok glad to here it can fly at reduced settings. Just try to not run wide open for more than a short burst. again congrats, very nice looking bird.

Gordon

Jul 26, 2006, 09:17 AM

Dave Brock's video of the Phantom's second flight is here:

Edit 28 July. Putfile seem to have cleared the interloper off my web page, so the video is now here:

http://media.putfile.com/Chris-Golds-Phantom

It's in widescreen format, so in the size box, click on wide.

Gordon

PhilLin

Jul 26, 2006, 12:28 PM

These say it all,

CG has been moved 1.25" forward and this model now flies fantastically!!!! :D

We are now a little nose heavy but that can be easily sorted out now we have tamed the beast......

Chris was cruising at 50% throttle. ( I have programmed a linear throttle curve into the transmitter) once I am back I will post what the cruising draw is.

Please add my congratulations for Chris' success! Now there is a small brother to my Bandwagon 102 (see attached). And Chris even had more details than I had. Hope the smaller twin will get more people to have a crack at it. There are so many colorful schemes for the F-4, serving over such a long stretch & in such large quantities :)

Moving CG forward 1.25" :eek: :D That seems to be quite a lot on a smaller plane. My 44" span flew definitely much more stable with a half inch more fwd CG. I lost it at Winamac 06 when its two top packs shifted aft during take-off :( I'm sure a half inch more fwd CG would have allowed enuf control to bring it back on the runway :o

Phil