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Building Tips and technical articles. => Building techniques => Topic started by: Steven Kientz on October 19, 2015, 02:51:50 PM
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I have a Sig Super Chipmunk wing kit that I'm going to use with a profile fuselage. It didn't come with any hardware. My question is, Should I buy a flap horn from Tom Morris, RSM or just use a nylon control horn and 3/32' music wire for the joiner? My next question is, If I purchase a flap horn what is the difference as far as where the flap and elevator linkages attach? I noticed some are straight and some are bent 90 degrees. I assume I need to stay at 1:1.
Thanks
Steve
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I have surface horns mounted on my (565 sq in) Tanager flaps and it flys just fine, my Banshee too. Just go with 1/32" ply top and bottom. I think the Tom Morris or the Brodak unit would be better though. The tilt forward design is to get the same travel up and down because of the angle on the flap pushrod. I'd go with a little more elevator travel not 1:1.
MM
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If you use the separate nylon control horn and there is any wiggle in the joiner, the airplane could fly poorly.
Keep in mind the need for the elevator pushrod to clear the flap.
You can get a linear control response with either a straight or bent control horn. The control system is three dimensional, so you need to do a three dimensional analysis to see if you got it right. I could send you a spreadsheet.
There is no aerodynamic significance to 1:1. It could work best with either less or more elevator than flap. Even better is a nonconstant ratio.
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I assume I need to stay at 1:1.
How well do you fly? If you're above Intermediate you should probably get or make a slotted elevator horn and experiment with different elevator:flap ratios to see what works best for your plane.
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Go to Tom Morris for controls..
That said, why use a profile fuselage??? A full fuselage will always be better. Profiles tend to vibrate and the tail surfaces are always moving. I know that many will argue with me, but in most cases when people tell me they are not ready for a full fuselage, it is the profile that is holding them back.
I know there are several newer profiles that are more rigid, but I still say why ruin the Chipmunk kit?
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Tom is so right about going to full fuse. Doesn't have to be fancy, look at the Hobo. Your engine will love you for it also. Two sides, top and bottom.
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I'm still very crash prone. I can usually repair and fly again. Profile is easier for me to repair. The only part of the Chipmunk kit I have is the wing, looking to pair it with a 36"(approx.) fuselage. Not looking to build a world beater, just something that can handle a few collisions with terra firma. I know a lot of people will say use the Skyray 35, but the majority of my engines are 40/46(LA). Besides I like building my own (granted someone else's wing). I have a Primary Force and a Naughty Girl to build, once I get past the basics.
How does one bend the T. Morris flap horns? Does it take heat and a jig to make sure the bends are aligned in the same plane? I know once installed you might have to "tweak" a flap. maybe I'd be better off buying the "custom bent" horns for the extra$$.
Thanks
Steve
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I've done it both ways, with an RC style nylon horn and joiner, and with a proper steel flap horn.
For quick and dirty flaps I'd go for the nylon horn.
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It hasnt been so long that I was where you are,, Tim can tell you about the plane he built to be durable,, and I thought as you did.
the first thing to know,, what is your aspiration? do you want to fly stunt, or fly sport?
It matters
also, a GOOD flying well trimmed plane is easier to learn how to do manuevers,, Look for my thread on my Impact ish profile,, and the tribulations I went through with it,,