C

chris mitchell

Well Known Member
Patron
I've read various previous postings about this topic and also looked at a number of builders web sites. however, I'd be grateful for any observations about the problems I've been having with this step over the past two days. Its very frustrating not to be able to move on with any confidence!

I've tried four methods(!0 and none seem very satisfactory - (1) the plumb-bob method that Vans specify seems pretty hopeless; (2) next we tried using 6 foot lengths of angle clamped to the ends of the gear legs and tried to get the lengths of angle parallel and the ends of the legs equidistant from a mid-line reference down at the tail; (3) then we tried getting the stub axles aligned with each other using a length of angle, with the gear legs equidistant etc, and finally we tried the method specified by Vans on drawing 45, which is a variation on (3).


No matter which method we use we end up with the same problem which is that the right gear leg looks too far back compared with the left, so that we start to have edge distance issue with the outermost rivet holding part number F802 in place to the skin, and also that the outer locating block U803 and the associated outer wear plate is not parallel with the longeron - if we get the 3/16" at the forward bolt, then the aft bolt is like 3/8" inboard - the left side looks good.

Instinctively I feel like I should pull the right leg forward and push the left one back - but then they will be different distances from the tail reference point. If I had to guess the cause of the problem I'd say the gear legs are not real mirror-images - I think the right one has some twist. Other possiblities I guess are that the fuse is twisted somehow (its a QB) or that I'm doing something dumb and incompetent - but any suggestions on how to proceed will be really helpful and appreciated.

Thanks

Chris :(:(:(

PS when I work out how I'll edit and add some pictures
 
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I'm no expert mind you, but I would think the primary goal, would be to get them parallel to each other so that it will track straight.

If the wheels/gear legs are not the same distance fore and aft, that isn't going to make a whole lot of difference in how it handles down the taxi/runway. So if it's not off by too much, I wouldn't worry about it and just concern yourself with them both being at the same line of travel.
 
Mine Too

After several attempts I found my right gear tower was further forward than the left one placing the right gear leg aft in the pocket to get proper alignment. Everything still seems to fit correctly but I did have to open up the fuse skin a bit to get proper edge distance. All of this is covered by the intersection fairings when complete. I also have a QB.
Bill Woods
RV 8 QB
 
I was lucky that mine lined up parallel while equidistant from tail....but I think I agree with the theory that parallel is more important than equidistant with the tail. This is important enough that to sleep better, I'd make a call to Van's and ask them. Sometimes, I just want to hear it from the engineering authority!

Paul
 
Laser

I started with Van's method and got more than a little frustrated. Then after getting idea planted from another thread, decided to buy two of levels with lasers. Hanger wall was 30ft from gear. Clamped levels side by side and measured parallel error on wall. Clamped level to each gear at wheel flat and measure spots on the wall. I figure if it is straight at 30ft it is pretty darn good. Also ran one laser down the center of the fuselage to get center point.

Found that if your fuselage is pretty straight the gear should end up pretty centered from weldments and bulkheads as well. After all was laid out, the bolt holes drilled an equal distance from weldment ends and each gear were the same distance from the bottom floor brace and firewall. At least mine did.:)
 
Almost there - good news!

Thanks for the comments. I thought you would be interested in the outcome - eventually, after staring at the set up for a while (like an hour) and trying to imagine what the problem was (obsessing about the apparent twist in the right leg) and thinking - am I about to be the first RV8 builder that can't get this step done properly - I moved the legs to where I thought they looked right, just by eye, mainly using the outer wear-bar edges and their alignment with the longeron. Then I clamped on the angles on and set about measuring, expecting to find that I would just about be able to achieve parallel axles, even if the measurements from the tail were way off, squeaking in with the wear-bar edge clearances. It didn't take much tweaking to get the angles parallel within 2mm at the ends of the angles (I'm using using 6 foot lengths of angle, centered at the axle-mount midpoint) and fine withthe edge distances. Then I thought, just for curiosity really, lets see how far out the measurement from the tail is - less than 5mm!! :D:D I just don't understand what I'd done wrong in the previous efforts. :confused:

Previously it just seemed like the right leg had to go so far back, but its such a reiterative process with a single movement affecting all the measurements that I think I just got more and more confused about what I was doing.

Anyway, I've just left everything now and will recheck the measurements a few more times before finally drilling holes this upcoming weekend.

What a relief!

Thanks again - its always helpful to have access to other builders' ideas and methods.


Chris
 
If I had it to do over, heres what I'd do... I'd get it all lined up, I used a $20 three way laser, then, drill the wear plates into the longerons first. I had the whole thing shake when I tried drilling into the weldment and everything moved on me. By drilling the wear plates, the bolts stay in and keep things lined up and drill the easy stuff first, then bolt them securely and drill the 805 i think it is? I'm pretty sure you'll be ok any way you go about it. Just my hindsight on the project.
 
Aligning and Drilling

I went through this about two weeks ago. I didn't have any trouble at all getting stuff lined up using five plumb bobs. I had big trouble initially getting the drilling correct. I would absolutely agree with the previous on drilling the wear plates first. I gave my whole stepwise approach in this thread:

http://www.vansairforce.com/community/showthread.php?t=22464

Who know why is was to funky to begin with. One of those mysteries of construction is that sometimes it just doesn't fit/work/function until you sleep on it and come back.

Good luck

Michael Wynn
RV 8 Fuselage
San Ramon
 
Jeffro - thanks - I can see that shaking/movement would be a problem so thanks for the heads up. We'll do it in the order you suggest.

Mike - thanks - I saw your experience/suggestions, and so that's exactly what I planned to do. Drills and reamers should be at home when I get there this evening.

Tom Agin, QB RV8 builder from New Jersey, is calling by on Sunday as he is in England for a few days, and as he's already done this step I'm hoping he will direct operations!

I've got to say - as have others -that this web site is incredibly helpful, and it will be a huge pleasure to meet someone from so far away with the same interest. Hope to post some pictures of the operation to complete this thread.

Chris
 
Chris, Jeffro has got it right, you need the wear plates in there first to hold everything together. In fact I never took them out when I removed the gear after it was over. No need. I drilled the wear plates on a drill press as I recall. Much easier! I didn't need reamers, just drilled them to the size specified with a cobalt drill.

Glad to see you ordered new drill bits. You'll need 'em. Also be sure to have some drill lubricant otherwise the bit will overheat and go nowhere.

I don't know if you have any laser levels. I'll bring over the small one I used on mine. No problem to throw in the suitcase. I managed to do mine with one plus tape measures, strings on the floor, etc. The laser level I have is small and with a magnetic base that sticks to the gear leg.

See you on Sunday!! My lawyer [solicitor to you] is drafting a disclaimer and legal release you can sign before you put your drill to it if I am supervising. I'll only know how I did when when I get it on the wheels at 60 mph.

Tom
 
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