Funplanesdude
Member
Hi All:
I am planning a modification to a Pietenpol Air Camper project that I am building. I am planning to make the wing using the Riblett 613.5 airfoil, which will provide better flight characteristics for me. I am a large pilot (6'4" and 250 before my diet...) and I live in a hot environment, so to make the project a more desirable plane for me, I am changing the wing's airfoil to the Riblett verses the original FC-10.
My question is about the formula spar strength if I were to add one rib bay to each wing. This would add 12" to each wing tip, and I am trying to determine spar strengths.
The standard spars are 1" thick and roughly 4.75" tall solid Sitka Spruce, and there are 2 spars in each wing, front and back.
Since the Riblett Airfoil is about 6 inches thick at the spar stations, I planned to make the wing spars to fill the total gap and I am thinking that this would be strong enough for the extra wing area that I plan to add. If I am adding over an inch to each spar's total height, and only adding 2 feet of wing span to the total wing area, how can I determine if this will be sufficiently strong enough for the design changes?
Also, I plan to move the strut connections to the wing out one bay from the original design to provide additional strength to the extension.
I want the final gross weight to grow from the 1045lbs to closer to the LSA limit of 1320lbs. I plan to put a 100 HP Corvair engine up front, so I know I have plenty of power for that weight, but I want confidence in the final design numbers to prove justified in the changes I make.
Can anyone recommend a book with formulas and design info that can guide this kind of decision?
Many thanks!
Mark
I am planning a modification to a Pietenpol Air Camper project that I am building. I am planning to make the wing using the Riblett 613.5 airfoil, which will provide better flight characteristics for me. I am a large pilot (6'4" and 250 before my diet...) and I live in a hot environment, so to make the project a more desirable plane for me, I am changing the wing's airfoil to the Riblett verses the original FC-10.
My question is about the formula spar strength if I were to add one rib bay to each wing. This would add 12" to each wing tip, and I am trying to determine spar strengths.
The standard spars are 1" thick and roughly 4.75" tall solid Sitka Spruce, and there are 2 spars in each wing, front and back.
Since the Riblett Airfoil is about 6 inches thick at the spar stations, I planned to make the wing spars to fill the total gap and I am thinking that this would be strong enough for the extra wing area that I plan to add. If I am adding over an inch to each spar's total height, and only adding 2 feet of wing span to the total wing area, how can I determine if this will be sufficiently strong enough for the design changes?
Also, I plan to move the strut connections to the wing out one bay from the original design to provide additional strength to the extension.
I want the final gross weight to grow from the 1045lbs to closer to the LSA limit of 1320lbs. I plan to put a 100 HP Corvair engine up front, so I know I have plenty of power for that weight, but I want confidence in the final design numbers to prove justified in the changes I make.
Can anyone recommend a book with formulas and design info that can guide this kind of decision?
Many thanks!
Mark
