Geometry, anyone?

Stuka Stunt Main Forum · 5 of 5 known posts recovered

Dzlstunter · Jul 15, 2001 08:42 PM

I am building a Freebird which has engine, wing, and stab all on the centerline of the fuse. The plans show a flap horn configuration which has one horn up and one horn down (with two pushrods) in order to separately operate the flaps and elevators in the correct direction. Is there a good way to accomplish this without having the flap horn configured this way and thereby using a more conventional bellcrank/flap connection? At this point I am considering a small vertical "transfer" bellcrank located immediately behind the wing. John

Steve Helmick · Jul 15, 2001 09:03 PM

#1 source

How about calling up Tom Morris and ask if he'll make up a custom flap horn with double levers? All he'd have to do is put two stock levers on one joiner wire. You want to have the pushrods at 90 degrees to the pivot & hingeline in all cases. I'd send him $ and a sketch to be sure he understands what you want, but his catalog is pretty comprehensive, so maybe he has stock bits that will work for the zero-zero setup. Steve

Dzlstunter · Jul 16, 2001 01:34 PM

#2 source

Steve: I think you are absolutely right about biting the bullet and going with the original designer's intent. So I built an over and under flap horn and it is sitting on the plane as we speak. We can end this string at this point. Thanks

Dzlstunter · Jul 16, 2001 01:35 PM

#3 source

LAST EDITED ON Jul-16-01 AT 01:39 PM (EST)

TigreST · Jul 16, 2001 02:55 PM

RE: Geometry, ...ask Col. Tom Mac ie: F-104#4 source

LAST EDITED ON Jul-17-01 AT 05:31 AM (EST)

Dzlstunt,
See if you can find a picture of Col. Tom Macs'.(sp) newest jet stunter; profile F-104 Starfighter. (think he posted them at RCO at one time?) He used a rather nice R/C elbow-bellcrank set up to allow the push rod motion to change direction, so that the "T-tail" config. of the Starfighter could be retained (ie: fore-aft motion became up-down motion). A similar set-up would also give you the required motion "direction change" needed to run two control horns that exit the same side of the wing/stab, .. be it top side, or bottom side of both. This mid point bellcrank (no elbow needed) may also give you some interesting tune-ability related to flap to elevator deflection ratio's. Ball-links would help to keep the system "tight", as in no slop. May have to file this one away for myself. Something to keep in mind for the next project, where control fit is a problem ..hmmmmm.

I've often wondered at the possibility of using the R/C separate-horn aileron control technology to effect stunter flap movements. Balllinks and threaded fittings would allow you to fine tune the "flap tweak" without bending the horns, ..just turn the ball links in/out as needed. But that's another story. Check out Col. Tom's F-104 linkage, it may give you idea's. Perhaps he'll re-post the pix here, ...hint hint.

Tony

p.s.: So now that I've re-read the starting thread, I see that I got lost along the way, . Don't play with a loaded computer when your half asleep guys!