Introduction My Builder's Log My Flight Log Tips List of Builders Gallery Ideas for Paint Links News





As those of you who have progressed to putting the nose gear together will know, the contraption delivered with the kit that's supposed to retract the nose gear doors doesn't work properly. Due to the way it was designed, it will only pull the nose gear doors almost closed, but no matter how you re-position it or tighten it, the doors will not be pulled up tight.

I'm aware that Lancair have a new mechanism in the works, and have seen pictures of the prototype on Don's web site. When I inquired about it, however, I was told that it would be an option, but that it was "not available!" Dunno what that means, so I built my own. The two pictures show it installed on my Legacy, one shot from above, the other from below, in the gear down, doors open position. The mechanism consists of two 5/16" chrome moly rods that attach to T-pieces on either end, each rod running through two Delrin guides that are mounted in an aluminum frame. The ends of the lower T-piece serve as the attach points for the push-rods to the doors, and the upper T-piece serves as the attachment point for the springs that hold it in the down position.

The assembly mounts in the same holes as the gear Up stop supplied with the kit, and by making slotted bolt holes in the mounting frame, the Up stop position can be adjusted the same as with the factory part. A 1/4" thick block of Delrin serves as a cushioning pad for the Up stop. To adjust the Down stop, there is a screw and lock nut at the top of the frame. The material cost was more or less nil, since everything came out of my various junk boxes. The 5/16" chrome moly rods were salvaged platen rollers from an old daisy-wheel printer (yeah, I know, that dates me!). If I ever make "production" models, the one change I'd make would be to use a stainless T-piece at the bottom. I'd run the rods about 1/6" through, then weld them, keeping the weld fillets on the under side so it would still seat nicely on the Delrin guides. For my prototype, I threaded the ends of the rods and attached the lower T-piece with 10-32 x 5/8" stainless screws, with internal tooth lock washers and lots of Loctite. The upper T-piece is attached to the rods with roll pins, so the entire assembly can be taken apart.

Locating the brackets on the gear doors turns out to be pretty critical. If they're too far outboard (i.e., near the hinges, the roughly 3-inch travel of the retract mechanism makes the doors open too far. Conversely, if they're too far toward the centerline, they won't open far enough, and won't open quickly enough to clear the wheel as it drops. The brackets need to mount on the hat section, so some kind of spacer is required so the hat section isn't just squashed when you tighten the attaching bolts. I drilled #12 holes all the way through, then enlarged the holes in just the hat section to 5/16", then added aluminum spacers. This seemed easier than sliding a piece of phenolic into place from the open end, but either way would work. The pushrods were made up of rod end bearings and some threaded aluminum rod. (It would have been easier to use all-thread and checknuts, but I mistakenly ordered male thread rod ends from ACS instead of female thread.)

All the parts and pieces can be obtained from Small Parts, Inc., except maybe the Delrin rod, which has to be at least 7/8" diameter to make the guides. Most plastics outfits have some around, but I'm sure it could be obtained on-line. There's quite a bit of machining involved, so it might get expensive if you have a shop make it on a one-off basis. I might make it available for other builders, but it depends on several unknowns: (1) How well it flight tests, (2) How much interest there might be, (3) what Lancair charge whenever their new mechanism becomes available, and (4) What it might cost to have some made in quantity.

Any feedback welcome. E-mail.

Jim Cameron
Legacy #232





Home | Introduction | My Builder's Log | My Flight Log | Tips | Legacy Builders | Legacy Gallery | Ideas For Paint | Links | Legacy News

Copyright © 2005. All rights reserved. This site is the builder's log of Don Barnes and for the purpose of sharing information and opinions related to building a Lancair Legacy. Any person using these images, ideas and tips does so at their own discretion and risk. No responsibility is expressed or implied and is without recourse against anyone related to this site. This site is not affiliated with Lancair International or Neico Aviation Inc., however, we love their aircraft.

Design by Cellar Ideas and produced with GoLive CS. Hosting generously provided by Rob Logan