Increasing wing span
Increasing wing span
(OP)
I am looking into various plans built airplane designs in the experimental category.
One airplane in particular has a lot of the right numbers for me as far as time to build, complexity and cost, but the stall speed is a bit higher than I like and the climb rate is lower than I like.
What I am considering is increasing the wingspan to solve both problems AND to boost its useful load slightly. The span is currently 18 1/2 feet (short) and I would stretch that to 20 1/2. The current wing loading is 13.7 lbs/ft^2 (1150 gross, 84 ft^2). At 93 ft^2 and 1225 gross, wing load would be 13.2lbs/ft^2
A) Would increasing the span work address the stall speed and rate of climb? (W/o getting quantitative)
B) What would be the structural considerations for the spar and wing structure to ably handle the additional weight of the wing and the load it carries in flight? Basically, is increasing the span as easy as adding two more ribs on each side, or would the spar need to be lengthened and the skin thickness need to be changed?
One airplane in particular has a lot of the right numbers for me as far as time to build, complexity and cost, but the stall speed is a bit higher than I like and the climb rate is lower than I like.
What I am considering is increasing the wingspan to solve both problems AND to boost its useful load slightly. The span is currently 18 1/2 feet (short) and I would stretch that to 20 1/2. The current wing loading is 13.7 lbs/ft^2 (1150 gross, 84 ft^2). At 93 ft^2 and 1225 gross, wing load would be 13.2lbs/ft^2
A) Would increasing the span work address the stall speed and rate of climb? (W/o getting quantitative)
B) What would be the structural considerations for the spar and wing structure to ably handle the additional weight of the wing and the load it carries in flight? Basically, is increasing the span as easy as adding two more ribs on each side, or would the spar need to be lengthened and the skin thickness need to be changed?





RE: Increasing wing span
As far as the structure goes, I would imagine that the thickness of the skin would not have to change. But you might want to have to look at increasing the thickness of the spars which would have to be a little stronger (higher bending moments)
Hope this helps a little (if it is still relevant).
Ori
RE: Increasing wing span
RE: Increasing wing span
B) If you were to just add more ribs to increases the span, can you please tell me the tail number, so that I never hop on that aircraft.
Increasing the span will increase the lift, and move the moment arm further from the wing root, hence giving a much larger bending moment. If there is not sufficient strength in the spar, and its connection to the fuselage, then it may fail.
Increasing the length of the wing will also decrease it stiffness, both in bending an torsion. This may reult in unwanted aeroeleastic effects (flutter, among others) if properly excited.
As already stated, the tail/rudder area may be needed. Due to the lower stall speed, the tail may need to be increased to maintain the same level of control at lower speeds.
Will increased wing span will probably mean decreased angle of clearance, which may be an issue if not landing perfectly wings level.
These are just a few of the issues that I can think of immediately, but I am sure that there are many others. So NO, it isn't "as easy as adding two more ribs on each side"
RE: Increasing wing span
You might have a swept wing (forward or back), in which case, increasing the span of the wing will change the position of the centre of lift in relation to the centre of gravity.
You might need to (slightly) reposition your CoG accordingly (forward or backwards) to maintain the right static margin.
The best way to increase climb rate is with a bigger engine !
The best way to decrease stall speed is through flaps.
RE: Increasing wing span
WIll changing the spand, chord, airfoils etc, be handled in the existing airframe or are you going to beef those up to handle the new loads?
Joseph Moylan
moygr1@home.com