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Mounts for wing-mounted wire gear

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Mounts for wing-mounted wire gear

Old 07-25-2005, 05:00 PM
  #1  
dabigboy
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Default Mounts for wing-mounted wire gear

Howdy all,

I just finished restoring my Tiger 2 in late '04. Among other changes, I converted it from tricycle to taildragger configuration. I've got probably a dozen or so flights on it since the restoration, a couple of hard landings early but since then all landings have been pretty smooth. However, the wire gear are starting to become loose in the mounts. I'm using a setup similar to the original tricycle gear.......I made some new mounting blocks from birch and glued them in front of the spar to move the gear forward, and drilled 1/8" holes to put the wire gear in.

The blocks were made by laminating two 1/8" slabs of birch with epoxy. They were then epoxied onto the front of the spar, between two ribs, oriented similarly to the original blocks (I also reinforced the ribs with 1/8" birch....the mounts seem to be holding up well).

Thing is, I didn't originally build this plane, so I don't know exactly how the original mounting blocks were installed. They appear to be 1/4" hard wood of some sort, glued onto tbe back of the spar, between two reinforced ribs. The gear never loosened up inside the mounts at all, and this is an 8+ year old plane. Is there some sort of reinforcement you're supposed to do after drilling the holes for the gear? The gear originally slid into my new mounts nice and tight, but now have a bit of play. I'm afraid it's only going to get worse the more I fly the plane.

One possibility is that my original drilling job was sloppy and the part of the gear that slides into the block was only being supported in a few places, thus bearing more than normal loads, and flattening out after some use.

I'm thinking of getting some metal tubing with 1/8" inner diameter and epoxying it into the blocks. This would eliminate metal-to-wood contact of seperate parts.

Thoughts? Suggestions?

-Matt Bailey
Old 07-25-2005, 05:48 PM
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hattend
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Default RE: Mounts for wing-mounted wire gear

Get a set of aluminum gear, put some 1/4" ply on the fuselage just in front of the wing, reinforce with tri-stock and bolt the aluminum gear to the wood block.

Transfers the loads to the fuselage instead of the wing and works just as well. If you buy an aluminum gearset that has a sweep back, mount it so the gear is back under the leading edge when the plane is level.

I'll post a picture of my mod when I get home.

Don
Old 07-25-2005, 07:12 PM
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dabigboy
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Default RE: Mounts for wing-mounted wire gear

Yeah, I've seen a few Tigers like that, but I reeeeaaaally like the look of the wing mounts better. But if I can't fix the wing mounts, I will probably end up going this route.

-Matt Bailey
Old 07-26-2005, 07:55 PM
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sbd-5
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Default RE: Mounts for wing-mounted wire gear

the birch is too soft and the hole for the wire is getting larger from the landing,like hitting a piece of wood in the same spot with a hammer.most lg mounts are made from maple a very hard wood.the easiest fix i can think off to reduce the play is to first melt candle wax all over the wire gear where it touches wood,just a thin coat to act as a release agent.mix up some 30 minute epoxy and put it in the hole and slot as well as coating the gear then install it.after the epoxy cures you should be able to flex the gear a bit to brak it's bond from the epoxy and it should be good and tite and last a long time
Old 07-26-2005, 10:30 PM
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dabigboy
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Default RE: Mounts for wing-mounted wire gear

Argh, wrong wood selection then. I should have looked closer at the snip from the Tiger plans someone posted here a while back. I didn't realize it was that critical. Thanks for the tip.

-Matt Bailey
Old 07-29-2005, 09:54 PM
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pilot_adam
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Default RE: Mounts for wing-mounted wire gear

Looking for some help converting a Tiger 2 to taildragger with the original main landing gear affixed to the Wing as in the tricycle option. Wondering about how to best go about balacing it, its somewhat nose-heavy.. if i counter it with tail weight will this affect flight performance at all? Thanx guys , any help would be appreciated.


Adam.
Old 07-29-2005, 10:26 PM
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dabigboy
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Default RE: Mounts for wing-mounted wire gear

Ehhh, you're not going to get around re-positioning the gear. I moved my gear to just in front of the spar (about the same distance as they originally were behind the spar), and I still had to bend them forward a bunch to keep the plane from tipping over occasionally on grass (and to keep enough force on the tailwheel for it to be effective). I have a page detailing the project here: http://rtccom.net/~mattb/tiger.html the pics don't work right now, but there's lots of text. Notice the ground handling problems mentioned near the top of the page..........I'm not sure I would even want to mount the gear in the same place if I were to do this again, I'd probably go forward at least another 1/4" or so.

My plane ended up slightly more tail heavy than before, due to removal of the nose gear, and added weight of the tailwheel and more covering in the tail. It was fairly docile before, moving the CG back very slightly like this livened it up a bit. If the plane flies well now, DO NOT mess with the CG to make the gear work. And if it's a bit tail heavy already for aerobatics, definitely make a note of the CG location and add nose weight after the conversion to make sure you maintain this CG.

If you were to add enough tail weight to make the plane even just taxi ok as a taildragger with the main gear in the same mounts (even if you bend them forward a bunch), the plane would probably be uncontrollable, if it even flew at all.

A probably simpler option would be to remove the old gear altogether and mount some aluminum gear on the fuselage just ahead of the wing. Some folks have done this, I stuck with the wing mounts as I felt it looked better, and provided wider stance and put the gear closer to the CG (better ground handling).

-Matt Bailey
Old 07-30-2005, 06:38 AM
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sbd-5
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Default RE: Mounts for wing-mounted wire gear

years ago there was a formula published to determine the location of conventional gear.if you have the plan draw a line dow perpendicular to the leading edge.measure down this line the total distance of wire strut and wheel for desired ground clearence.now measure up half the distance of wheels being used to locate the axle location.now draw a 15 degree angle from this pointtowards the wing using the perpendicular line as the base.this will indicate the centerline of the mounting blocks.

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