SR71 - 40 inches

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This is a 40 inch SR71 built of 5mm depron/biofoam


It has two tractor motors, one each in the LE of the nacelles.. The plan has some modifications in the aspect ratio and other dimensions, and the details are as below





Controls are just elevons on the outer wings (outside of the nacelle)  with 1 X 9gm servo each.. there is no moving control surfaces on the central portion of the wing or on the vertical tails.. btw the vertical tail surface are straight and not canted inwards. Note , the LE droop on the other wing panels. The landing gear is  tricycle wire skids.. to protect the prop and underside of the aircraft.. have a look at the photographs below


The finished aircraft , just before the 1st flight. Notice the bty compartment... because of the low roll/ lateral stability the bty had to be in the center, hence the fuse had to modified.. and before that the CG had to be right..


First flight was done with the CG at 30.5" from the tip of the nose.. it turned out to be a bit nose heavy and was moved to 29.5" .. or 10" (25.4cm) from the LE where the wing joins the fuselage stakes

Setup 2 X 2212 1400Kv motors with 7045 3 blade props and 2200mah 3S bty.. AUW 840gms
The motors are contra rotating so you need CW and CCW props.. Any suitable ESC will do, I am using 30A (that is what I have).. 
NOTE IMPORTANT : The ESCs are connected to CH 3 and CH 4.. imp take out one red connector from any one of the ESC so that the RX does not get dual supply.. (this is advisable  and may not be necessary .. depends on the ESC)









The 1st flight was good.. she flies at 50% throttle.. Second flight was with the CG at 10" from the LE of the wing or 29.5" from the nose tip.. It is a stable and docile aircraft with good fast and slow flying characteristics (the outer LE droop helps)  ..and awesome to look at .. very pleased..

Here is a flight video
https://www.youtube.com/watch?v=yXxycxUaB4k&feature=youtu.be

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