Will Aldridge
Well-Known Member
I've been thinking about flaps for my plane. The idea of having 3 flaps on each wing (it's inverted gull like a corsair) was always a deterrent but I just came up with the idea of splitting the middle flap on each wing in half and combining each half with the flap next to it. The flaps would have piano hinges on the bottom surface which would run full span (a la ch 650) except for the curved part that came from adding the portion of the middle flap to each wing.
As implied the complexity of the system is the biggest deterrent, and if I can't keep it simple enough I stay with speed brakes I've had drawn in for the past year, but I'd rather have flaps if I can. So I've been brainstorming ways to actuate the four panels while keeping things simple. The idea I have right now and that I am asking advice about is this:
Have the control horn protruding from the bottom of each flap attached to a cable that will pull the flap down, with a spring attached to the top of the flap and the aft spar that will retract the flap when tension is relieved from the cable.
I've heard I think that the the Piper Cub uses a similar setup though I've never seen it. In A&P school right now I'm working on reassembling a Piper Cherokee and the flap torque tube has a cable running to it from both ends of the sprocket with a spring used to retract the flaps even without the pilot trying to move the handle (the button must still be pushed). In my idea there is no return cable just the spring from the flaps to the rear spar.
Thinking of failure modes and consequences; what if the spring broke? Flutter and probably losing the flap and more than likely crashing as a result. I could however have it rigged so if the spring broke I could extend the flaps which would mean I'd be flying pretty slow to wherever I would land but I would at least make it to a runway.
Anyway enough blabber on my part. If this is a bad idea shoot it full of holes and hopefully suggest a better one. Remember the objective is a simple, reliable actuation system.
As implied the complexity of the system is the biggest deterrent, and if I can't keep it simple enough I stay with speed brakes I've had drawn in for the past year, but I'd rather have flaps if I can. So I've been brainstorming ways to actuate the four panels while keeping things simple. The idea I have right now and that I am asking advice about is this:
Have the control horn protruding from the bottom of each flap attached to a cable that will pull the flap down, with a spring attached to the top of the flap and the aft spar that will retract the flap when tension is relieved from the cable.
I've heard I think that the the Piper Cub uses a similar setup though I've never seen it. In A&P school right now I'm working on reassembling a Piper Cherokee and the flap torque tube has a cable running to it from both ends of the sprocket with a spring used to retract the flaps even without the pilot trying to move the handle (the button must still be pushed). In my idea there is no return cable just the spring from the flaps to the rear spar.
Thinking of failure modes and consequences; what if the spring broke? Flutter and probably losing the flap and more than likely crashing as a result. I could however have it rigged so if the spring broke I could extend the flaps which would mean I'd be flying pretty slow to wherever I would land but I would at least make it to a runway.
Anyway enough blabber on my part. If this is a bad idea shoot it full of holes and hopefully suggest a better one. Remember the objective is a simple, reliable actuation system.
