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Multiplex LS3 kit build

Started by Darkstar56, July 13, 2015, 18:09:11 pm

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Darkstar56

I am currently building a Multiplex LS3 kit that I got from a friend who was giving up.

The kit has a very complex system to operate the elevator with huge ply bellcranks the height of the fin, approx 200mm ish.

I am intending to put an HS85MG servo in the fin to do the job.

What I cannot decide is whether to put it down at the bottom of the fin and put a small bellcrank system at the top or whether to just put the servo at the top and live with the weight of the servo at the top of the fin.

The fin is epoxy glas and integral with the fuselage.

Does any one have any thoughts on which way to go?

TIA

Max
"... acquisition of knowledge is never too dear."
Sir Francis Walsingham, Spymaster to Q Elizabeth 1.

Anthony

Hi Max, put the servo at the top or bottom, whichever fits best and have a short direct drive to the elevator, shorter the better. Fiddle around with the orientation of the servo and pushrods until it feels right and no slop.  Ant.

paulinfrance

I had one it's a great flyer, put the servo down as near as you can to the bottom of the tail it will reduce whiplash on landing that cracks and eventually breaks the tail.
Mode 2 THE only way to fly

Darkstar56

Thank you both for those thoughts. Think I will put the servo at the bottom and use a small bellcrank that I have at the top.

Max
"... acquisition of knowledge is never too dear."
Sir Francis Walsingham, Spymaster to Q Elizabeth 1.

w8racer

Quote from: Darkstar56 on July 15, 2015, 08:38:50 am
Think I will put the servo at the bottom and use a small bellcrank that I have at the top.

Do you need a bellcrank at the top? Is it possible to connect the vertical pushrod directly to the elevator and minimise any slop?
Robert Welford

paulinfrance

Yes of course, I put my elevator servo in the bottom of the tail in  my ASW 19 rippin-top 3.75m


Mode 2 THE only way to fly

Darkstar56

Quote from: w8racer on July 15, 2015, 23:52:43 pm
Do you need a bellcrank at the top? Is it possible to connect the vertical pushrod directly to the elevator and minimise any slop?

That is something I have done in a previous Tee tail model and it worked well.

Not too sure I can get a good run in this case but I will look again.

Thank you for the prompt.

Max
"... acquisition of knowledge is never too dear."
Sir Francis Walsingham, Spymaster to Q Elizabeth 1.

Anthony

Quote from: Anthony on July 13, 2015, 20:46:20 pm
Hi Max, put the servo at the top or bottom, whichever fits best and have a short direct drive to the elevator, shorter the better. Fiddle around with the orientation of the servo and pushrods until it feels right and no slop.  Ant.

Hellooooo......exactly what I said..........!