The model is photographed on a standard UK aviation map. Click the image to zoom in
The model is photographed on a standard UK aviation map. Click the image to zoom in
This Dak was scratch built, and weighs in at a shade over 60 grams (2oz). It is powered by two lithium 140mAhr cells, two series KP00 motors with gearboxes on a GWX ESC and props by Gordon Brown. Standard radio equipment is used, i.e. GWS Pico servos and receiver. These were lightened by removing the connectors and replacing with directly wired links as short as possible. Non essential bits were removed, i.e. the radio case, bottom of the servo cases and fixing lugs. The wings and tail are from 3mm depron, front fuselage from EPP, rest from 1mm depron. A 3mm depron profile fuselage was used as a construction aid, and mostly removed as the build progressed. Tail is scale outline and scale rudder / elevator. U/C wires from left over mini push rod piano wire, in torque tubes fitted to the leading edge of the wing. The tubes are left over outers. Engine cowls are from 2mm wallpaper foam, and hollowed EPP at the front fuselage and cowls to make it a little more robust. (Have you seen me fly?). The 3mm wings were shaped, cold forming by hand, sanded to round the LE and taper the TE. The Fuselage 1mm depron was harder to roll, and needed heat and care. 90deg C and wrapping in newspaper helped here. Paint is spray can acrylic (for RC cars), with some detail added by biro. Decals printed on paper and simply stuck on. The scheme was chosen from a picture found on the web of an Air Atlantic Dak dressed WW2 RAF style. The front fuselage is retained by tiny magnets top and bottom, so it knocks off easily in a bump and gives easy access for battery charging.
Inspiration came from seeing a Dak from Coventry based Air Atlantic flying very low over local field as part of a remembrance day event, and the technology learnt at Aeronutz - http://www.aeronutz.flyer.co.uk/. The drawings were obtained on line from a copy of the full size operating manual, and scaled up from the printed page about 4.9 times. http://members.tripod.com/pcmuseum/dc3/. The 1/40 scale was chosen after careful weighing of the RC and motors, copious wing area and loading calculations, and settled by the size of the smallest wheels I had. The wing area is around 0.7sq ft, so my target wing loading of 3oz/sq ft is not far out. There is easily enough reserve to carry a retract servo, but in the interests of simplicity I have elected to keep it a simple and durable as possible. This is my first ever scratch scale model, perhaps surprising as I have been aero modelling since the 60s, and a member of CADMAC as early as 1972. (Who remembers the Stanley Model Aircraft cardboard Apprentice and Craftsman trainers of the 80s?)
Flies with excellent climb and cruises at less than half throttle. Elevator control is positive, rudder requires slightly more anticipation. Sounds just right with the two gearboxes rattling away at cruise power. It has flown indoors before and outdoors before being painted. With over 5 grams of decoration it still is capable of non scale aerobatic manoeuvres! These sometime are required to recover for indoor situations or radio glitches.
Graham Stanley
Coventry
England
Graham@Modelfly.com
Contact the club at cadmacweb@leezpc.freeserve.co.uk