Tuesday, April 6, 2010

A little wing-work

So the next step is the one that I've been putting off the longest, actually cutting the wheel-wells for the retractable landing gear. I was extremely nervous about removing so much of the wing, but decided I finally needed to get over my fear and do it.

I don't have any pictures of the wing during the process, but it basically took me an afternoon of fitting, cutting, refitting, testing, and generally worrying if I was doing things right to get the wheel wells cut.

I'm actually pretty proud of the final product.


Oh, I bought a new sanding bit for my dremel that made all the world of difference. It let me make the wheel wells with nice smooth sides and flat bottoms and made cutting the wing way nicer than cutting the servo hole was. I used a Cone Grinding Stone (with a flat top).

There's a cylinder one that I think would work just as well.

Here are some more pictures of how it all fits together with the landing gear actually in there:





The servo isn't actually hooked up yet, since I ran into a bit of a snag. In order to get the amount of movement that I'm going to need to actually work the retracts, I'm going to need to put a larger head on the servo (to give it more movement distance). Since I'm basically out of wing at the leading edge, that means I need to move the servo back a little bit so there'll be room (since I can't go right to the edge of the wing).
The probem? Well, I'd already cut the hole for the servo! (Big mistake it turns out.)

So, in order to get the servo moved back, I needed to plug up the hole. I used a bit of foam I had lying around and glued it into place.


I still need to re-cut the hole to re-position the servo, but I'm definitely not going to cut as much out this time. I think I only need to make a square hole large enough to just barely fit the servo through... I also shaved off some extra space on one side so that the linkage will be able to reach the bottom of the servo head. I think it might actually work!

Anyways, after getting the wheel-wells for the landing gear cut, I decided I should probably strengthen the wing a little bit (I'm worried that I managed to weaken it enough that it'd just break off if I landed too hard). I just happened to have some carbon fiber strips that I'd bought by accident earlier on hand, and decided to glue them along the wing to add some strength.



You can see I had to cut a channel to lay the strips in and epoxied them in there. I'm going to have to spackle it when it dries before I glass the wing so that it's nice and smooth, but that can wait for another day.

As a side note, I found that I actually had to cut out a V shaped channel in order to get the strips to slot nicely into the wing, and applied generous amounts of epoxy to secure it. I tried just having a slit in the wing and jamming the carbon fiber strip in there, but it was putting a lot of stress on the wing and I was worried it wouldn't hold up under stress.

Next up, some more spacklin', sandin', glassin'


Well, after a long winter of procrastinating the weather is finally looking nicer and now I'm thinking of flying again, and that means I'm making progress on the plane again.

The next step is to get the retractable landing gear setup, and so with that in mind I bent and cut the gear. I installed the wheels and am holding them in place with some rubber stoppers I had lying around from some pushrod connectors.


I probably need to secure the wheel stops with a dab of glue, but I'm going to leave that until I'm sure everything is sitting right. It turns out bending wire exactly is harder than I thought, so one is very slightly longer than the other. I'm hoping it won't be a problem.

I went through a bunch of the little tasks that I'd been putting off as well. I finally glued in the plywood that will hold the elevator and rudder servos in,


I finally got around to gluing in the rods that will hold the engine nacelle on,


(Tip: I left the nacelle actually assembled as the glue dried to ensure the pieces would fit together night and snug. I used vaseline on the ends of the tubes to keep them from getting glue inside them and a peice of paper-towel in between the two halves to absorb any excess glue. Worked great.)

And made some cardboard sidewalls for the exhaust ports,


Also I got the steel plate and magnets glued in for the cockpit (the hatch that covers the battery),



Now the cockpit sits in nice and tight and is held in place by the magnets. It's actually beginning to look like a real plane now (about time).


Next stop, more wing-work.