Ultimate 10-300

Ultimate is a superb 3D model and pretty accurate to scale as well (outline, that is). Small enough to transport easily but big enough to give decent stability. This is a good model which I strongly recommend if you want to fly 3D or learn to fly knife-edge.

I have two versions: The 280 sq in version is suitable for double CDRom motors (or the Axi 2208/34) and the 200 sq in version is for single CDRom motors (or the Axi 2204 or similar). The larger one has a 30" span and the smaller is 25". They weigh about 8oz and 6.5oz (184g) with 3x340 LiPols. They both fly well with up to 860mAh 3 cell Lipo packs. The plane will knife-edge with ease and even do knife-edge loops. Prop-hanging is quite stable although needs quite a bit of right aileron to prevent torque rolling. The roll rate is brisk and rudder has very good authority. I use mainly 8-9g servos on the larger model. On the small one I still use a 9g servo on ailerons (because there are four of them) but 6g on Elevator/Rudder. A safe CG position is indicated on the plans but I normally fly with it 10mm or so further back to improve elevator response.

As with Mumbo Minor I used 2mm Depron for the fuz and 3mm for the rest but 3mm all round will be fine. I used a hollow 3mm spar to strengthen the bottom wing. On the larger version I used 1/64" ply spars on both surfaces of the top wing but I no longer think this is necessary and now rely on the carbon spar on the bottom wing only. Both planes feature an all-moving tailplane pivoting on a 3 or 2mm carbon rod through a brass or ali tube. The carbon is usually a bit a of a loose fit so drip thin cyno on the carbon, allow to cure, sand smooth with fine sandpaper until you get a snug but free-moving fit in the tube. A small problem to note is that on take-off the elevator can stall the model and even act as a brake against the ground. The take-off technique is to open the throttle and to leave the elevator neutral until you have flying speed. A small amount of elevator will get you airborne after which large movements are wild!

As usual you may build the model but may not profit from the design. Please send me photos of colourful designs and suggestions for improvements. Plans in various formats follow. Check the reference line and use a photocopier to adjust the size or drop me an email...