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Building Tips and technical articles. => Building techniques => Topic started by: Stan Tyler on June 05, 2007, 02:30:13 PM
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I've never used adjustable elevator horns before and I'd like to know if it's best to use only a hatch on one side for access to the elevator horn for adjustment or if a hatch on both sides works better.
I'm planning on using Tom Morris ball link flap and elevator horns with the elevator being adjustable with the slider nut. All of this is going into Chizler for classic at VSC next year.
Thanks,
Stan
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If you use the slider nut, then all you need is the hatch on one side.
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For just a slider elevator horn (not using an adjustable pushrod) I cut a vertical slot in line with the horn about 1/8th" to 3/16" wide and 1/2" tall. The socket head driver will fit in no problem.
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Tom sells horns with the vertical slot already cut into them. He also has the sliders sold separately. I have one on my Cavalier profile. Works like a charm. H^^
I cut the slot in the fuselage side to access the Morris slider horn once it's installed and the plane is finished. Maybe I was confusing with what I said. ???
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Surprisingly, there's already a laser cut slot in the fuse side about 1/8" wide and about 1/2" long that appears to be in just the right place for the elevator horn adjustment.
Bill, do you cover the slot after adjustment or just leave it open? I would think that exhaust oil and such would quickly get into the slot. I think that a piped ship wouldn't be as much of an issue but a side exhaust could be a problem.
Also, anyone have any thoughts on pushrod length adjustments when the flap/elevator ratio is changed? It would appear that when the elevator is adjusted, the bias between the flap and elevator would change slightly.
Thanks,
Stan
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Hi Stan,
Sometimes I put a piece of hinge sealing tape over it, like when it is a "muffled" plane.
Haven't experienced any troubles with the flap/elevator ratios, nor have I heard anyone else having any. Since it's all in trimming, I guess that just isn't noticed during the process if it does affect a change.
Keith Trostle and I have exchanged a lot of posts on the subject of adjustable elev. ratios, so maybe he will read and reply. ;D
Bill <><
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Well, I only use a hatch on one side. And an interesting hatch it is. I got for the round, screw in unit. Works pretty well.
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Hi Stan,
Sometimes I put a piece of hinge sealing tape over it, like when it is a "muffled" plane.
Haven't experienced any troubles with the flap/elevator ratios, nor have I heard anyone else having any. Since it's all in trimming, I guess that just isn't noticed during the process if it does affect a change.
Keith Trostle and I have exchanged a lot of posts on the subject of adjustable elev. ratios, so maybe he will read and reply. ;D
Bill <><
I do not visit this part of the forum very often, so just picked up on this matter. I think the question is about access hatches or slots in the area of the elevator control horn to be able to adjust the flap/elevator ratio.
I have a bit of experience with different approaches to do this. Every flapped stunt ship I have built in the last 30 plus years have had sliders on the elevators (in on case on the flaps) to be able to make adjustments to the flap/elevator travel ratio. I have often rigged up hatches on the side of the fuselage beside the elevator horn and held these hatches in place with flat head 2-56 screws/blind nuts. Oil seepage has not been a problem into the structure around those hatch areas. Actually, a simpler and cleaner approach is to build a hatch and just hold it in place with a piece of wide clear tape. (That means that you have to clean the area to assure that tape stays stuck. Light, simple and clean.) Even if you do use small bolts to hold the hatch in place, it would still be advisable to completely seal it by a piece of clear tape.
The other way is to do what has also been suggested here particularly if all you are doing is to get into whatever your slide mechanism on the horn is to just have a slot on the side of the fuselage next to the horn/slider. Cover the slot with clear tape to seal it from oil getting into that area. There is basically no stress or stress risers caused by putting a slot or hatch in that area. There are essentially no critical loads being carried by the fuselage structure in that area as long as you have a substantial mount to hold the horizontal stabilizer in place.
In other forums at other times, there has been an Australian who has posted his approach to adjustable flap/elevator ratios with an elegant mechanism below the wing that is part of the bellcrank assembly. The mechanism allows adjustment to the flap to bellcrank response and adjustment to the elevator to bellcrank response. Access is through a hatch on the bottom of the airplane. I will try to find the name associated with that and maybe find the relevant forums/posts.
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I always install a hatch because I have often needed to ajust the pushrod length to cause the stunter to turn the same with up control as it does with down or the other way around. This also, of course, gives me acess for ajusting the ratio as well.
Blessings,
Will
P.S. _ I love Tom's opposite thread connectors for that use, no need to disconnect the ball joint from the horn! Just turn it the proper direction and viola!
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The Australian that Keith Trostle referred to is Brian Hampton from Adelaide. If I remember correctly, he uses the name Downunder on some forums.
Cheers
Geoff
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Everyone,
Thanks for the information.
Stan