Building and Flying Related Boards › miniMax, Hi-Max, and AirBike General Discussions
JGlassFNPAugust 28, 2019, 11:33am
Ok I am approaching the time to mock up my wings and as we know there is a 3 degree angle built in the root to allow for the dihedral angle. Now I need to know if I’m doing this right before cutting my metal for my struts and wasting my money. If the wing root and tip were on a level plane, and want to rise 3 degrees over basically 12 foot then how many inches would it be blocked up at the wing tip? I used a right triangle trig calculator that rendered 7.5 inches. Does this sound right? I will post the picture of the calculation. Thanks, James
radfordcAugust 28, 2019, 4:07pm
I used this calculator to check and it shows pretty close to what you have:
https://www.inchcalculator.com/rise-run-degrees-calculator/It actually shows that a rise of 7 5/8" is closer to 3 degrees. If you can get accuracy to 1/8" you're better than most.
Bob DalyAugust 28, 2019, 4:45pm
For small angles the tangent and sine trigonometry functions are equivalent so confusing the two doesn't hurt in this application. For 3° they are 0.05. So for a 139" wing, the tip would be raised 7".
Keith103August 28, 2019, 4:50pm
Distance from wing root to tip = 139 inches.
Tan of 3 deg = 0.0524
Rise of wing tip from root = 139 x 0.0524 = 7.2836
I used 7 and 1/4 inches for verifying the dihedral.
Keith103August 28, 2019, 4:59pm
I used a similar calculation to figure out how much to tilt the top of root rib from vertical.
JGlassFNPAugust 28, 2019, 7:51pm
Sounds good. I appreciate you guys. James
Greg DoeAugust 28, 2019, 8:42pm
Don't worry about it. 6 1/2" or 8 1/2", you will never know the difference.
mullacharjakAugust 30, 2019, 4:04pm
Bob DalySeptember 2, 2019, 4:40pm
Sure would. And if one determines the position of the strut attachment point on the wing relative to the attachment point on the fuselage or axle one can simply use the Pythagorean theorem (z2 = a2 + b2 + c2) to calculate the precise strut lengths without blocking up the wing at all. For example, the Himax main wing strut attach point is 1.37" behind the fuselage strut point (the strut angles slightly aft) and 38.47" above it and 63.38" out. These distances can all be determined from the plans. Then the strut length is 74.15" plus the necessary bolt hole edge distances. The same procedure will produce the rear strut length.
