This is an indoor or parkflier semi-scale Piper J3 Cub.
One of the benefits of e-plans is the ability to easily scale models up or down to your own requirements !
Winter (and often Summer) here in Scotland can sometimes not be conducive to flying outdoors and, not wishing to miss out on some flying, I decided that an indoor r/c electric was the way to go. Having seen some of the pictures and reports at the E-Zone, I thought it shouldn't be too difficult to "roll-my-own". I'm not a scale flyer by any means, but felt that some of the indoor models lacked that "something".
So, having decided to build, how do you select a model? I'd like to say that I spent months poring over scale model books and magazines for a suitable subject - I didn't - my friend Mike had a plan for a rubber Cub and I had a few pictures - and the Cub is the right "shape" - so that was it !
I presume other people have built aircraft exactly the same way, but if they have, I haven't seen it. The principle is to cut the foam into sheets and build it just like a balsa model - makes life very easy and doesn't require too much thought. The wings are wire cut to section using special universal templates shown on the plan.
I used a couple of different techniques in some places - the windscreen and upper front fuselage were heat formed (hair dryer and Coke can) to get the correct shape - saves having to make templates to hot-wire cut foam block. The wheels were turned from the same foam and fitted with dowel centres - I used a lathe, but it's just as easy with an electric drill - once sprayed with matt black acrylic, they definitely look the part. The special sanding tool is shown on the plan.
First flights (as usual with any new model) were a bit scary - new model, never flown r/c inside before, lots of free-flight indoor folks watching - but I got away with it. I'd like to say that it flew perfectly first time - it didn't - there was insufficient rudder authority, so I resorted to taping another piece of "non-scale" foam to the rudder - this cured it, but it looked nothing like a Cub fin) Another member at the club suggested making it all flying - this is what the final version has, and works extremely well. I built a second Cub for my friend, making a few modifications in the process - more dihedral and the all flying rudder (hereinafter referred to as an AFR :-) - he added his gear slightly forward and pushed the CG about 10 to 15mm forward of mine and, on the first flight it flew PERFECTLY - very slow and very controllable. I have since modified the prototype by changing to an AFR, adding more dihedral and moving the CG forward - it too flies perfectly - and SLOOOW (well slow is relative - probably closer to a brisk walk or a slow run).
Indoor r/c flying certainly adds another dimension to flying (actually another five to be precise - four walls and a ceiling - all of which have to be missed ! )
Technical Details...
Span
1200mm (about 48")
AUW
260g (8.5oz)
Motor
Simprop "Slow Drive 250"
Speed Controller
Jeti JES 05 BEC
Prop
APC 254*120mm (10"*4.7") (comes with Simprop slow-drive pack)
Battery
6 * 110mAH Sanyo
Construction ...
Fuselage
4mm polystyrene
Tail surfaces
5mm polystyrene
Wings
6mm polystyrene (clark - Y profiled)
Wing struts
3mm shaped dowel
Wheels
58mm dia turned polystyrene
Finish
Either bare foam, or sprayed with Tamiya/Humbrol Acrylics
The Plans ...
Note: The plans are free, but the copyright © is MINE! (basically, don't start selling kits commercially or I'll get annoyed and send someone round to break your legs :-).
The plans are now in PDF format rather than expect everyone to have a CAD program to print them.
All the plan units are in millimetres !!! (we don't do Imperial units here - 95% of the world use the metric system, and I have ten fingers - not twelve - and FYI, Wilbur and Orville were metric - rant mode off :-))) There are two sheets to the drawing - both A0 size - the main plan plus a sheet of parts outlines so you can cut out all the bits and stick them to the foam without destroying your plan :-)
Download ...
Garden Cub Plans
Garden Cub Parts