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Aug 15, 2019, 01:54 PM
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jwfinn's Avatar
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Discussion

In search of 200 mph with foamboard


Yes, you read that right, and yes it's silly and ridiculous, but I want to do it anyway. Here are a couple of setups I've tried and what they've gotten me:

Speed Deamon V1 (28" span): Turnigy 2826-2200, APC 5.25x6.25, Lumineer 6s 1300 30C, 116 mph (radar measured).
Super Deamon V3 (24" span): HET 2W-25, APC 5.25x6.25, Mystery 100A esc, 4s 2200 60C, 116 mph (radar measured at half throttle; abandoned further attempts for safety's sake).
Combat Deamon (50" span): Aeolian 4260-720 kv, APC 9x10, 80A esc (can't remember brand), 2x 4s2200 60C (8s2200), 125 mph (GPS indicated, Pitot showed 120, but it was consistently reading 10 mph below radar indicated speeds in calm air during partial throttle passes).
-tried this plane on a GM 10x23 on 6s and burned through two motors, never got much over 100 mph.
Sharknado (40" span): GoolRC 3670-2800, APC 6.5x6.5, Red Brick 200A opto, 2x 3s2200-25C (6s 2200), 143 mph (GPS indicated).

Here's a video showing some of the goings on with the Speed Deamon which started this process:
Speed Deamon: a 100+ mph foamboard plane that you can build! (7 min 9 sec)


And here's footage of the other three planes (Sharknado footage is all on a 4s 2200, haven't uploaded the 6s footage yet):
Compilation of 100+ mph Foamboard Speed Planes and Hotliners! (16 min 9 sec)


Any advice on power systems and the like to go faster would be welcome, bearing in mind the context of these planes being made from foamboard (I'm using the FT water resistant foamboard on these models). I'm using carbon rods for some fuselage reinforcing and of course 3/16" cf tubes for the wing spars. Would like to stay with that basic arrangement so that other modelers can easily repeat the results. The original Speed Deamon proved decently popular and several others have been seen flying at various fields.
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Aug 15, 2019, 01:58 PM
Free Flight rubber flyer
jwfinn's Avatar
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And for reference, a couple photos of the Sharknado, my current fastest foamboard plane. Ecalc is saying it's drawing around 170A on the cheap Turnigy 3s2200 pair. I already killed a pack doing that; the other pack in series survived. I've got some Xilo 6s 1250 packs on the way to run in parallel; I've tested those individually to about 120A without damaging them, so hopefully that along with a spinner will get me some more speed.
Aug 16, 2019, 07:48 PM
Wake up, feel pulse, be happy!
Piece's Avatar
The best type of crazy 143mph with foamboard is already cooking pretty good. Your fastest one definitely shows improvement and refinement over the earlier attempts (thinned/sharpened, etc.).

It looks like you're on the right track with power systems. The trick will probably be to keep slimming the airframes down and mitigating drag everywhere you can. It's not easy with foamboard. I suppose glass would be against the "spirit of the game", so to speak, and hotwiring airfoils doesn't make sense with this construction style, so you might have to blaze some trails here that nobody has really been down.

In any case, I'll be watching this project with interest

Here's one of mine from way back. The wing is made from two laminated Depron layers, sanded to shape, with a 1/4" fiberglass tube embedded in the underside. Power system was a 70g 3850Kv heli motor, APC something, and 3S 1800mAh. It died of an aft CG, but its (identical) successor clocked 115mph by Doppler.

Latest blog entry: Jeti ESC resto-mod
Aug 17, 2019, 08:35 AM
Airspeed is my drug
MikeRx's Avatar
I love inexpensive speed!

Tmotor F80, 2500kv
Kamikaze 80a esc (8s)
4x4.5" APC quad
650-1050 mah 75c, 8s.
The pictured 28" can outrun the 130mph Avanti at half throttle!
The foamboard models need sharp and stiff trailing edges for speed.
See my carbon t.e. in the Minishark thread..
Latest blog entry: 250 gram auw speed!
Aug 26, 2019, 09:37 AM
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57sailplane's Avatar
Keep the same power set up and make air frame smaller. Like everyone else says your already scooting.
Last edited by 57sailplane; Aug 26, 2019 at 09:44 AM.
Sep 03, 2019, 09:24 AM
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jwfinn's Avatar
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I got a few more Xilo 6s packs recently so I could fly this plane on good batteries. Going from a pair of Turnigy batteries to a pair of Xilo batteries drastically upped the power, but I burned out the 3670 inrunner on my second pass, recording another 140 mph pass. Ooops.

After taking some measurements, I concluded that I could still get the plane to balance with a 40mm inrunner, so I ordered a GoolRC 4074-2250. That is an absolute beast of a motor. Balance was...interesting...

With a 6.5x6.5, the speeds were predictably lower, around 120 mph, so I upped it to a 7x10. Ceilings were low and visibility unexceptional on Saturday, but I still got in a flight with it. First pass was 130 kts (my transmitter readout is in kts and haven't figured out how to make it convert on screen))! With the batteries warmed up, entered another pass, starting around 300', diving to 200 and then holding level after I hit the throttle. Less than 5 seconds of power and then she coasted for a long while. 144 kts!!! I landed after that; She's a happy bird and needs a spinner before I do anymore flying.

So I'm officially in the 150 mph foamboard club, which is a fantastic feeling, and she's a good 10 mph faster than Ben Harber's Yellow Jacket. Since these were GPS runs, the speeds are of course somewhat questionable, however having seen 150 mph planes on many occasions, I have no doubt she's doing every bit of that and more.

Video will be forthcoming.

57sailplane mentioned making the plane smaller. I'm a bit hesitant to do that. My early foamboard speed birds were all in the 20-28" span range. They became horrifically uncontrollable as I upped the power to go faster. It just stopped being fun, which was why I started building bigger and then just packing in more and more power to go faster. This plane is 54.6 oz all up with two 6s1250 Xilo in parallel. Pretty hefty for a 40" span, but there's enough wing area to slow down nicely for landing with crow braking. The glide is quite impressive, although it's gotten much faster as I've added bigger batteries and motors.
Last edited by jwfinn; Sep 03, 2019 at 12:59 PM.
Sep 14, 2019, 10:45 AM
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New speed record! The Sharknado gained another 10 mph to achieve 175 mph today (GPS indicated 152.9 kts). The new Graupner 42mm spinner definitely played a major role in achieving this speed. There's much more to come, but I stripped a flap servo somewhere along the way and that made the model start getting rather unhappy. Probably time to stop using cheap servos in these planes now that we're pushing FAR beyond the realm of normal toy airplane speeds.

At this point I'm going to have to start doing research on ways to beef up the power system. I'm running a Red Brick 200A esc which has hopelessly undersized wire for the 230A+ that I believe this plane is drawing. Cooling inside the fuse is terribly inadequate and I need to open things up to provide more cooling (or cut a hole in the top of the fuse so that I can surface mount the esc to expose its heat sink to the airflow). Also I've gotten away so far with XT60 connectors, but that just isn't safe and I'm surprised I haven't killed them yet. I'll probably just go up to an XT90 feeding into the ESC for now, but eventually it needs bullets.

Anyone who's got some wisdom on this, please provide input because this is far outside my knowledge base. The goal is to stay cheap, so a Castle esc or something like that is kinda outside the realm of what I want to do, if at all possible. It looks like cleaning up the airframe a little more will get the desired speed (stab is double layered foam, for example, GPS is mounted externally, etc, etc. Plus if we cut down on the internal resistance of the power system by upping the wire gages, it should be able to dump more power into the motor.

Oh one other thing--those cheap Chinese inrunners are AMAZING.
Sep 14, 2019, 11:14 AM
Registered User
Wow! That is awesome!

Sincerely,
Doug and Becky
Sep 16, 2019, 09:35 AM
Free Flight rubber flyer
jwfinn's Avatar
Thread OP
Flight footage! I don't have the 175 mph run on here yet, but it's not that impressive since I never got below 300' during that run. Enjoy...it's a good, loud airplane.

Fastest foamboard airplane in the world! (7 min 43 sec)
Sep 16, 2019, 10:12 AM
Registered User
Great Job! 200mph is sooooooo close!

Sincerely,
Doug and Becky
Sep 16, 2019, 12:07 PM
Youtube channel : solentlifeuk
solentlife's Avatar
This gives me a sense of Deja Vu .....

Few years back - Need for Speed group started on Wattflyer ... spread to RCG ... but seemed to die out after I hit 222kph (138mph).

I know - long way short of the 175mph here.

What did we use ? Hobby King Parkjet. The original one - not the later smaller 2S version.



My 222kph was achieved with 4700kv 450 Heli Motor, 5x5 APC, 80A ESC, 3S 1500 ... but run time was VERY short ... ESC and LiPo were dead after it ...



My last PKJ had twin 3400kv 200 size Heli Motors ... 4.1x4.1 APC props, twin 80A ESC and 3S 1800 ........... couldn't get it to fly ...



I've since stopped going such crazy speeds - getting older and eyes not so good ... but I wish all here best of luck and achieve your goals.

"Need for Speed" ...................... YEH !!


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