Always in the register of the " faster, better, cheaper ", the method that I propose to you is fast, effective and economic! Just find the following components:
- an alveolate polypropylene plate (corrugated cardboard kind out of plastic...). One finds this marvellous material in do-it-yourself stores or building material sale in the form of panels of building site on which are reproduced the address, the number of permit building, etc... In most of the cases, you will get it free of charge or in the worts case it does not cost more than 3 Euros.
- a bottle (plastic preferably) of mineral water Badoit. The new bottle is appropriate very well and will give a look of hell to your foamy.
- a 3 mm diameter carbon stem found in the kite department of any sport store.
- 2 clamp (pieces of stell wire)
- double face and Scotch glass fibre armed tape.
- a speed 400 powered in 7,2 V (the 6 V could be fine too)
- an adapted propeller (6x3 " with folding blades)
- a 7 elements battery (I use the red SANYO 650mA but a 1000 mA would be suitable too)
- a variator with BEC and brake (Easy Line 3000 of KONTRONIK is a good deal )
When you have in hand the carbon stem and the alveolate plastic plate, you will not be able to resist the desire for threading the stem into a cell. You will note whereas they are made one for the other and that the stem re-enters in force without deforming the plastic. Nature is well made... one will use that to make a support motor/battery resisting and ultra light.
Find the gauge for polystyrene cutting of and draw a beautiful root profile on the plastic plate (cells parallel with the under-surface). Take a cutter and cut out all that while taking care to remove the trailing edge with the dimension of the control surface.
You will stick this profile with double-faced tape between the two half beforehand cloth-lined wings. For the covering it is better to use reinforced glass fibre Scotch tape ay the level of:
- leading edge
- trailing edge
- control surfaces
- central part of each half wing (approximately 15 cm on each side)
The remainder of the wing is ccovered with the white Scotch
tape.
Once the profile stuck between the wings, some tapes of
scotch/fibre-glass will come to reinforce the junction. Position
these tapes in the direction of the wing so that the glass fibres
are used for something!
Take your battery and roll up a plastic rectangle undulated around the accumulator, the cells parallel with the length of the pack. You should cut the plate so that the plastic comes free in and out without play. The length of this sleeve must be 28 cm approximately.
Remove the four corners of this part over a 4 cm length
approximately to preserve only the part in the prolongation of the
face punt of the battery pack. The two legs obtained to both ends
will be used to fix the whole under the wing.
With a same aim, but also to ventilate the accumulator and to
facilitate its installation, detach with a cutter a leg on both
sides of the battery. (cf photographs which are for sure clearer
than my explanations...)
Once stuck under the wing (with the bouble face on the punt part, and with the armed Scotch tape on the four legs, you'll just have to thread 2 sections of 30 cm carbon stem in two cells separated by 2 cm (leave 5 free holes between the two stems) to make the horizontal cradle of the motor support.
Finally another 30 cm stem is threaded in one of the central profile alveoles to supplement the driving support.
To fix the engine with this support, you just wrap to pieces of steel wire around the motor ... Nothing simpler !
For the adjustment of the centre of gravity, I positioned the face before reducer to 11 cm of the nose of the profile. The sleeve support of battery starts to 7 cm of the nose and finishes 18 cm further. It is while exploiting the position of the accumulator in the sleeve that one obtains a correct centering (approximately 12,5 to 13 cm of the nose of the profile).
Once found centering, the carbon stems is withdrawn from the cells, coated of liquid néoprenne adhesive then positioned back.
It remains to cut out a superb fuselage in the bottle of badoit. For that to cut up the neck to 6 cm top of the cork, remove the bottom to preserve 20 cm of bottle. Align the airfoil chord on the medium of the bottle (the line of junction of both half moulds is apparent and will be used as reference) and trace at the good distance the part before profile which will have to be cut out. Thread this cap on the engine and the wing, the lower part comes to cover the end with the battery support, the top will be scotched flat on the suction face, it hides all the interfacing of the servos as well as the receiver
Everything included, you'll obtain a wing loaded with approximately 30 grams per square decimetre.
And flight in all that ? It is rather pleasant, much more nervous than in the glider version. It is necessary nevertheless to pay attention because I obtained one or twice beautiful gimlets caught up in-extremis a few meters above the ground...