A very exciting but challenging model! I built the canopy and shroud in 1996 after seeing the full size at Farnborough. The plane inspired me and I and thought it would be an ideal project for an Electric. Work pressures, and the realisation that this probably should not be my FIRST electric (!), dampened my enthusiasm a bit. However, after hearing Nigel Nixon describe his experiences developing a 1/3rd scale model for a film, I knew I had to complete the aircraft which I did in April 2000. I'm now pleased because it is an interesting subject and it flies well. Thanks to Tony Shortell and Phil Metcalf for some excellent in-flight photos...
|Wing area:||1041 sq"|
|Wing loading:||25 oz/sq'|
|Motor:||Astro 40 Cobalt #640|
Changing to a 25mm Crocodile motor
|Gearbox:||Astro standard 1.63 : 1|
Changing to direct drive
|Prop:||Graupner 11x7 3-blade|
|Prop speed:||7700 RPM|
|Batteries:||20 x RC2400|
Changing to 6 Lipos
|Motor current (full power):||33A|
Probably changing to 40A
|Power loading:||60 w/lb (input)|
|Static thrust:||1.9kg / 4.2lb (take-off; fresh cells)|
|Flight times:||10 minutes (excluding thermalling!) conservative flying in good weather (8 mins with 2000's); 6 or 7 minutes with heavier throttle usage on 2400's such as in brisk winds.|
|Receiver:||Futaba 6ch single conversion|
|Servos:||2 x FMA360 (Rudder/Elevator) 2 x Futaba S148 (Ailerons) 1 x Futaba S6 (Nose wheel)|
|Speed control:||Jeti JES80 (JES40 would be adequate)|
|Rx battery:||700mah 4 cell nicad|
|Model design:||Scratch built|
|Airfoil:||Eppler 210 (slight undercamber). The full size actually uses a NASA GA(W)-1 airfoil but I only found this out later from the airfoils site you can find on my Links/Further info page.|
|Wing construction:||Conventional; 6mm spruce spars; 3/32 balsa ribs; cap strips; 1/16" leading edge balsa sheeting; built-up ailerons. Two pairs of spars pass through the shroud to support booms, u/c and wings. Only the front spars are used in the outer wing panels. The Rx is housed in one of the centre wing panels to minimise electrical wiring lengths.|
|Canopy/Shroud:||Plugs made from balsa (shroud) and insulation foam (canopy). Finished product moulded out of fibreglass, carbon and epoxy resin. Home-made windows pulled with 0.25mm vacuum-forming plastic over separate moulds (using a domestic 2-bar heater to soften the plastic).|
|Booms:||Built-up from 1/8" balsa formers and 3/32 balsa sheeting (cut to 1/8" strips). Glassed with 1.5oz cloth after sanding. Each epoxy'd in place between two ply wing ribs.|
|Undercarriage:||4mm piano wire (a bit 'wobbly' but adequate); 100mm main wheels; steerable 70mm nose wheel on coiled 5/32" leg.|
|Covering:||Solarfilm on flying surfaces; canopy and shroud sprayed.|
|Extra features:||Detailed cockpit; full lenght Pilot.|
Windows held by retaining screws which only need about 1 turn to loosen to allow plastic to be released.
Wings panels attach with 1/4" ply joiners, retained with two strips of Velcro.
The plane thermals in reasonable lift.
|What would I do differently?:||The incidences and perhaps motor thrust are probably slightly out as the plane requires a bit of up-elevator trim for level flight but then climbs when power is reduced.|
To minimise electrical wiring, I used long plastic pushrods (on rudder and elevator) which change length slightly in different temperature ranges.
I increased the wing area proporationately from 100" wingspan to 108" to reduce wing loading. This was not necessary.
Home-made wheels have not been successful on this aircraft as they seem to take a beating (especially the nose wheel).
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