Firebird25

Yesterday, when reviewing the Hobby Lobby catalog, I noticed ready made spoilers for sailplanes. That made me think that such a device may be an effective way to curb the tendency of the Sr Telemaster to balloon on landing. I plan to finish an ARF and also built a kit this winter and if this provides an effective solution, I will incorporate it. Anyone care to share your thoughts about that?

highhorse

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Have you considered reflexing (both up when mix switch thrown) the ailerons ? Not hard to do w/ comp radio. MUCH simpler than insalling spoilers !!! If not familiar w/ the concept do a search for "crow"

good luck to you, Don.

Firebird25

Don,

The thought certainly crossed my mind and your suggestion is a good one, but those spoilers looked like something different. I am just toying with the idea...

Thanks &

highhorse

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I hear ya. Sometimes different for it's own sake is half of the fun !!

crasherboy

Go for it. That is how we learn. Will it work well or will it be a flunk? Every improvement started with an idea,lets see how it works out.

BMatthews

Spoilers would definetly bring the model down and result in less tendency to balloon. But ballooning is mostly caused by incorrect methods for landing approach. Try flying with the nose a little high but still well shy of the stall. The added drag from this will help bring the plane down more predictably and result in a total lack of ballooning. But it is a trifle more tricky to do it this way and if the model has too nice a glide it may just not want to come down very well. Then it's back to the drawing board....

The other option is inboard flaps that come down a full 90 degrees. They add some lift but mostly they add lots of drag to help slow the model down and quickly beed off speed when you lift the nose back to level. A variation of this is a flap that has a flat forward portion that fold upwards to form an upper surface spoiler when the other portion deflects down. I'll do a little sketch later tonight of this and post it.

Firebird25

Bruce,

Thanks for the help. I have both an ARF and a kit of this model. It's probably easier to incorporate a set of flaps in the ARF and go the route of the spoilers with the kit.

While I have spent most of my professional life in the Marketing/Sales end of aerospace, building this is going to be a good learning experience for me, as I am a rather recent convert to RC Model Aviation. Having more fun with this than I thought possible. It's probably regarded illegal in some quarters...

BMatthews

This is a sketch of the combo spoiler and flaps setup I reffered to. Mostly they are just speedbrakes since any lift the flap portion provides will be counted by the spoiler effect of the upper blade. But as a drag maker I suspect it would work very well. I think these could be made as a fairly small portion of the trailing edge span and still be very effective. Like perhaps the inner 25% of the span?

seanreit

My Feedback: (60)

Bruce,

My composite Arf Lightning incorporates the device you are referring to, and yes, VERY effective.

I refer to it as a speed braking flap.

FWIW.

Sean

Firebird25

Bruce,

Your sketch has been added to my building info. Seems like an effective way to bleed some speed from the critter when landing. Thanks again!

rscarawa

I have seen this used on Telemaster 40s in the 1980s and it worked well. Controlled speed as well as reduced the need for down elevator with flap deflection.

pimmnz

And very similar to Hanno's flaps on Super Sicroly and Curare.
Evan.