What is the best split elevator setup?

[madkiwi]

Can anyone please help me. I'm doing a large scale cub (yes don't laugh) and want to build in some redundancy. I've decided to go with split elevator setup but need to know whether it is better to drive each half elevator with a seperate servo, or use something like MK dual elevator crank assembly to drive both halves with one servo. I think because I want some redundancy the 2 servo way is the best, but I have the MK crank and thought maybe I could utilise it?

Is it possible to use 2 servos linked together that then drive the crank to drive halves? If one servo dies the other servo can still drive both halves? Will this be a problem? I have a computer radio so trimming individual halves wont be a problem but crank will reduce any slop etc. Not sure what flying with one half elevator would be like!

Thanks in advance


Dwayne :)

[vintage1]

half an elevator is no problem unless the other half is fully deflected...in which case there might be a problem.

You need to examine each potential failure mode and assign a probability and a degree of liklihood of it causing a crash.

Then do the mahs and work out which redundant solution will essentially cover most of the possibilities.

In the final analysis what you are looking to do is to increase the mean time to catastrophc failure. No more than that.

As the first part of the exercise you list all the possible failure modes you can think of, and assign a tentativve degree of probaility, and a degree of seriousness.

E.g. take an elevator hinge that results in partial or complete separation of the hinge along one side.

Is it better to perserve the integrity of one half and let the other rip free, ? Or connect the two halves and hope that one side can effectively keep the other attached enough to land the plane?

And so on.

No magic answers.

Just a lot of thought experiments and a fair bit of basic maths.

Which will all come to naught if the plane is so heavy it breaks its wings :D