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Building Tips and technical articles. => Building techniques => Topic started by: Airacobra on January 26, 2009, 08:04:18 PM

Title: Flap horn on a Profile.
Post by: Airacobra on January 26, 2009, 08:04:18 PM
Just out of curiosity, can some of you show the setup you use on a profile. I have seen some folks use the standard plastic horns and others using something like the Morris offset horns. I was hoping some of you guys could shed some light on your technique.
Title: Re: Flap horn on a Profile.
Post by: Crist Rigotti on January 26, 2009, 08:37:46 PM
Keith,
I use an offset horn.  The pictures says it all.
Title: Re: Flap horn on a Profile.
Post by: Airacobra on January 26, 2009, 10:05:45 PM
Yes it does Crist, Thank you for the post.
Title: Re: Flap horn on a Profile.
Post by: Greg L Bahrman on January 26, 2009, 11:24:57 PM
here ya go
Title: Re: Flap horn on a Profile.
Post by: Airacobra on January 27, 2009, 07:03:11 AM
Thanks guys, the input has been very helpful.
Title: Re: Flap horn on a Profile.
Post by: Russell Shaffer on January 27, 2009, 09:56:02 AM
Would either of you guys have a picture of your setup before covering?  Thanks
Title: Re: Flap horn on a Profile.
Post by: Steve Helmick on January 28, 2009, 09:31:58 PM
One of the bigger problems with the nylon R/C horn is that it's usually attached to the inboard flap. Then, the flap joiner wire has to receive & transfer the torque to the outboard flap. With the horns shown, the lever applies the torque to the wire, then both flaps. If anything, you'd want to apply the torque to the outboard flap...might eliminate the need to use a 'wart' on the outboard flap, ya know. For the same reason, it would be logical to have the flap horn on the outboard side with any sort of flap horn...the outboard torsion bar being shorter.

Anyway, most those R/C horns are just too flexible, so if you just have to use one, get one for Giant Scale and mount it on the outboard flap. Give it a flex test, if you can. Glass fiber reinforced nylon would be ideal. Cheapies will not be a good choice. I'd be glad to use 1.25" at both flap and elevator. You can use one bolt through both ball ends at the flap. Put the elevator pushrod closest to the fuselage, to reduce the pushrod/flap interference. Adjust the control ratio to suit the plane's weight. Don't fail to experiment with this, you'll learn a lot!  mw~ Steve

Title: Re: Flap horn on a Profile.
Post by: Dennis Moritz on January 29, 2009, 07:34:15 PM
On Alan Brickhaus' recommendation I doubled the horns on my Twister. Guess it helps.
Title: Re: Flap horn on a Profile.
Post by: Steve Helmick on January 29, 2009, 08:50:08 PM
On Alan Brickhaus' recommendation I doubled the horns on my Twister. Guess it helps.

That'll work! Another good option is the long steel Sullivan control horns. Given some time, I could come up with a Pn., but not real soon. Gotta try to get ready for flying Saturday. Tower stocks them, so you can look 'em up in their big cattledog.  n~ Steve
Title: Re: Flap horn on a Profile.
Post by: Randy Powell on January 30, 2009, 02:00:39 PM
I would usually use an offset horn like those shown, but the current profile I'm working on, well, that's really not going to be an option. So I'm planning to use an aluminum inset into the flap (with appropriate reinforcement) and music wire for the connection between the flaps. Sigh...