|Jul 19, 2012, 10:53 AM|
Joined Jan 2012
Need advice on design and build of a large scale model airplane;
Before I buy parts and build this model, I would like some of you, experienced individuals in design and build of such models, to verified my design calculations and recommend if this model will fly, or not, as designed. Most of all, I am not sure that 13 lb. weight of airplane (not including engine and fuel) is the correct weight for this size of a model.
Wing Span = 134” ; Chord = 22” ; Aspect Ratio = 6:1 ; Area = 2950 Sq. In.
All I have at this point is an Engine runs at 7200 RPM, 1.1 hp , torque of 0.811 ft. lb./sec.
I am presenting here the results of my design calculations (based on googled formulas and web sites calculators):
Cruising Speed = 55 mph
Propeller Size = 20 x 8
Total Airplane Weight = 20lb (engine + fuel = 7 lb.) that leaves 13 lb. for the construction materials, controls, battery etc.)
Wing Loading = 15.62 oz./sq. ft.
Thrust-To-Weight = 1.17
Cl = 0.128
Lift = 19.3 lb (used rho=1.18 kg/m cubed) – not sure why this number resulted in less than 20lb). The 20 lb number given above was used in calculating Wing Loading and Thrust-To-Weight). Should I use the 19.3 lb number instead or what should I use for my final total weight target?
I can provide the formulas/calculators I used for all the numbers, if needed. Just wanted to save text space.
Thanks from David
|Nov 05, 2012, 04:28 PM|
|Nov 09, 2012, 07:56 AM|
I've bought 3 short kits from Bob Holman and he does TOP NOTCH work! The plans are clear and the parts are well done. I've heard negative opinions on other short kits providers, but never been disappointed with Bob.
Here are the three:
Carl Goldberg Sailplane
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