The World Models SPITFIRE (sort of...) 

 

 

 

 

The World Models Company in China manufactures many ARF models and they have a series of "Air Combat" models that seem to be made for conversion into electric. 

 

Wingspan:   1220 mm    Wing area:   28 sq dm 

Weight:       1410 g (My model ca 1500 gr) 

 

There is the Spitfire (of course...), Zero, Thunderbolt and the Yak-9. All are the same size and shape, except cowl, colour and markings. When you look inside, you can see it is a light- weight construction. Mostly Lite-ply and holes.

My first set-up was a Kyosho AP36L Special (normally one of the more powerful ferrites) on 8 Panasonic 2000 NiMH. The gear is an Olympus 2.33;1 beltdrive, Graupner CAM Prop 11x8. 

 

First test flight, 22 May 2003 

The test flight was really disappointing, I could take off, but the power just was not to be found for more than flying around in level flight. OK for a first aileron trainer.... 

 

I measured the amp draw - only 20A static! It should have been close to 30. I tried re-timing but could not find a better set up. There is probably something wrong with the motor.

 

 

 

 

 

Second test flight, 29 May 2003 

I made some (?) changes: a new motor - a  Kyosho Magnetic Mayhem, a 10 cell pack of Sanyo 1950 FAUP NiMH. This is  a new cell that seems promising, weight is only 39 gr and they are good for at least 30A (I have seen 50A mentioned, but have only tested up to a bit over 30A). I use a Graupner ECO CAM Prop 11x6. 

 

With the new power train I got a completely new aircraft! I have lots of power; big loopings from level flight, vertical climb (not for ever, but enough for a couple of rolls), slow rolls and avalanches.  

 

The CG is probably moved aft a bit with the new gear. I tried to spin, expecting a spiral dive but got a real fast rotating spin. No problem to stop it though. 

 

The Olympus belt drive is an excellent choice for this model. There is not much sticking out of the cowl and the motor gets direct cooling air. It is also a very quiet gear! I added a separate air intake for the batteries, 30A for a NIMH may generate some heat! (No problem though,as I found after the flight test. The batteries were just warm, not hot.) The air outlet is on the underside, just in front of the tail (and I also needed the hole to be able to remove the old control rod tubes).

Lots of space inside. Receiver away from the batteries/cables. I forgot to solder  the capacitors on the motor - no interference noticed! (I will add them nevertheless...). 

The original control rods were very stiff so I substituted NyRods with wire ends. 

In general: good behaviour and more than enough power for some aerobatic flying. 

I really can recommend The  World Models Aircombat series for an electric conversion with a Magnetic Mayhem on 10 cells and a gear! 

BUT.... 

do not use a prop larger than a size giving you 25-27A!!!! 

My using a 11x6 and drawing 30+A ruined the motor in ca 15 flights. The collector was totally worn down and so rough that it used up the brushes in only 1-2 flights. A 10x7 might be a better choice.  

 

I made an attempt of using my new LRK brushless outrunner (350/20/12,5), the same 10 cells, but a more suitable propeller; 12x8. Talk about POWER!!!! 

I had to throttle down after take off, it went too fast! Unfortunately I had not heard of the interference problems people had earlier in the day.... After some strange behaviour of the airplane, I first blamed this on the high speed, it started to make up/down elevator movements while I made a turn, and then it stopped responding on my control and dived into ground. 

 

(Later found out to be interference from the motor, picked up by too long motor cables, through the ESC and into the receiver)