My own trainer!

With all the recommendations for a plane for Sarah I though I would try to design and build one.

The criteria were in order.
Very cheap, light, robust and 3 channel (rudder and elevator).

I had to hand a 3000kV Emax 2805 (£3.75) and a 12A ESC (£5.99) which rather dictated a small fine pitch (6x3) prop driven by a 1300mAh 2s (£2.99) along with two 3.7g servo (£1.79 each).

After quite a bit doodling with various 'Cub' type designs I kept coming back to a pod and boom pusher layout as it gave the greatest crash resistance for its target weight of 9oz.

So what could be done with a fishing pole boom (£1) and a full sheet of 3mm Depron (£2.99)?

First the wing made up of three 12" panels, the centre flat with generous dihedral outer panels. Rather unusual construction with no spar, just the Depron skins drawn over Depron 'spacers'. At 6.25" chord and 1" deep giving a fairly generous 16% t/c ratio.

In effect a hollow foam monocoque. The two wing joints were reinforced with a tissue bandage glued on with PVA.
The complete wing weighs only 1.2oz yet held only by its tips it can support an 18oz centre load. This represents the stress approaching 8G with a 9oz airframe so it should not break under aerodynamic load.

Following my usual practice the rudder and elevator servo are right at the back buried in the fin, in fact they provide most of the support the whole tail feathers.

The wing pylon, tail feathers and the rest of the fuselage are all built up from 3mm Depron (there is still 1/5 sheet left). The only balsa in the whole structure in the fin spar and I am not sure even that was really necessary.
It looks like this.

It even uses my super cheap second hand 2.4 radio (£30 with 2 receivers).

By no means perfect it needed a big chunk (1/2oz ) of lead and a over size battery in the nose but it flies well enough at 8oz all up.

It is being rebuilt to move things around a bit so it should end up 1oz lighter.

Cheap in LSD (you have to be certain age to know what that means!) but in man hours no way.

Hehe, have you made it flame proof, stream proof, cabbage proof (allotment proof), tree proof and erm Sarah proof

Looks fantastic, 3 channel (rudder and elevator)-is the third channel the one that picks up radio 2 then?

Throttle Sarah ,brilliant idea and the most important factor --cheap ,well done

The Beard wrote: Throttle Sarah ,brilliant idea and the most important factor --cheap ,well done

Throttling me wont shut me up you know!!

You're a true gent Quorneng though I'm not sure there is such a thing as Sarah proof

Not just the trees Eric

I heard that!!

What Receivers does it need

Ive forgotten!!!!!!

willowlea wrote: Ive forgotten!!!!!!

Haha You cant say that when the model is in a power dive and someone shouts "up elevator"

Well you CAN if you have pleanty of glue

Garry

beats me pushing the throttle up as I was the first time thinking I was going up hahahha!!

It will take the receiver you are likely to get but as it is really only a park flyer you could lash out big time and buy an Orange R610 that is compatible with your Spektrum for:

wait for it!

£7.38 post free!

Quorneng wrote: It will take the receiver you are likely to get but as it is really only a park flyer you could lash out big time and buy an Orange R610 that is compatible with your Spektrum for:

wait for it!

£7.38 post free!

Sarah, these are the same as the ones I showed you the other night, cheap as chips. I use them more than the orginal Speccy ones now, and I've never had a problem to date. I often add the satellite, mainly for added insurance, but also because I fly much higher and further out than your average park flyer will (I have a big race course to cover), but I've never had a problem without the satellite either.

cheers chaps, will get ordering this weekend then- anything else I need to get?? Apart from a shed load of depron and glue