Performance Evaluation Wanted
 

To convert the Wing Mfg A-26 I elected to use two Gary Wright Endoplasma/GP Gear Box systems to power the plane. MotoCalc claims the configuration should work well. So here is the results:

MotoCalc estimates the thrust would be 112.7 oz. I measured 64 oz! To measure the thrust I set the plane tail first on my digital scale and had two friends gently balance the plane. Under full power the plane weight decreased 4 lbs. Not the seven (7) MotoCalc estimated.

So my questions are; Do you believe MotoCalc, do you think my thrust measurement is valid, what would you do to check for problems in my configuration?

System info:
Motor: Kyosho EndoPlasma 16T; 3785rpm/V; 2.5A no-load; 0.022 Ohms.
Battery: Sanyo HR-4/5FAUP; 10 series x 2 parallel cells; 1800mAh @ 1.2V; 0.006 Ohms/cell.
Speed Control: GP- C-50; 2 controls (separate); 0.003 Ohms; High rate.
Drive System: Great Planes Gearbox 4.6:1 3-Blades; 2 motors (parallel); 11x7 3-bladed (Pconst=1.11; Tconst=1) geared 4.6:1 (Eff=95%).
Airframe: A-26 EndoPlasma; 748sq.in; 147.6oz; 28.4oz/sq.ft; Cd=0.048; Cl=0.46; Clopt=0.6; Clmax=1.11.
Stats: 70 W/lb in; 56 W/lb out; 26mph stall; 36mph opt @ 73% (16:01, 123°F); 41mph level @ 82% (13:12, 129°F); 963ft/min @ 17.7°; -309ft/min @ -5.6°.

Your help and ideas will be appreciated.

RE: Performance Evaluation Wanted
 

I have never been a believer in negative measurements. If you can find way to measure positive thrust on your scale THEN you will be able to prove MotoCalc wrong.

Cheers, Phil

RE: Performance Evaluation Wanted
 

It sounds to me like the motors are running at about half throttle, like you're trying to run both motors from one battery. Have you cycled the packs? Check their voltage during and after charge? How are you charging them? Do you have a Whattmeter, or know someone who does?

Each Endoplasma setup, with a 12x8 prop, should be able to hover a 3lb airplane, presumably producing at least 3.5lb of thrust.

If it were me, I'd run each power system completely separate.

RE: Performance Evaluation Wanted
 

Thanks for the reply Matt,

Each power system is separate, Endoplasma, GP600 4.6:1 gear box, GP- 50A ESC, 10 cells Sanyo HR 1950FAUP 4/5A NiMH. Throttles are slaved using the mixing function of a Futaba 9C.

I have not cycled the packs. I will, No load voltage after test was 13.7 and 13.8 on the two packs. I use a Hitec CG355 charger. I do not have a wattmeter but it looks like I better get one.

Possible issue is my 3 blade 11x7 prop, MotoCalc likes it slightly better than the 12x8 2 blade. I have just received a couple 12x8s that I will test.

I will follow up on your idea that the motors are operating at 1/2 throttle. The GP C-50 ESC sets the low and high throttle position at turn-on... maybe.....