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Canopy Frame Not Wide Enough

snoopyflys

Well Known Member
Cabin Frame Not Wide Enough

Hi Gang,

Working on building the cabin frame for my -7a tipper and after measuring and remeasuring the width of the frame and the width of the fuse at the skins countless times, I find that after riveting the canopy frame together that the width winds up being a tad bit narrow, 42 1/32" instead of Van's plan callout of 42 5/32". Not sure how to go about fixing the latest issue in my build. Can this be salvaged by shimming it up with some .063 stock on each side of the mounting brackets? Or is this part critical enough to start over :eek: ?

Thanks,
 
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Snoop,
I remember solving this by turning the frame upside-down, bracing it against a padded (but solid) surface, and gently/firmly bending the frame outward. Small movements, then remount and recheck. I don't have immediate access to my builder's manual, but it mentions something about this.

Take your time. The canopy and frame is just one of those frustrating parts of an otherwise brilliant kit.
 
Are you talking about the forward frame not the rear hoop? Now is a good time to assess the match of the contour to the forward skin and subframe. I put mine in a hydraulic press to bend it. I would suggest that you begin matching it to the contour, then when that is done, recheck. Most likely it will match.

This frame is tricky to get matched all the way around. I took a lot of time to make it match only to move on and found it changed. It is flexible and has to be all assembled to really get fitted. Proceed with that in mind.

Good Luck.
 
Hey Bill,

Yeah I have a tendency to refer to the cabin frame as the canopy frame when they are totally different parts. This is the cabin frame (a.k.a., The Roll Bar) in my -7a. Sorry for the confusion :eek:

Dan
 
Hey Bill,

Yeah I have a tendency to refer to the cabin frame as the canopy frame when they are totally different parts. This is the cabin frame (a.k.a., The Roll Bar) in my -7a. Sorry for the confusion :eek:

Dan

Ok, that part is really really stiff. If it is really 1/4 inch too narrow, then the best bet is to remove and reinstall (remake) the splice. Bending is a problem because it is so wide. Mine is 1/16 off and I am waiting until final install of the plexi to see if I want to fix it. It was a bear to get flat.
 
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I have to agree. I don't think you can stretch the roll bar.... Like was stated... might take the splice apart and do it make new spacer blocks and re rivet it.
Jack
 
Roll Bar Too Narrow

Dan: My roll bar was equally narrow as your's. I wrote Van's, got a response from Ken Scott.

Below is a copy of my email and his answer. I'd ask them about it before you do it over, see if you get the same answer I did.



[Steven: it's pretty easy to expand the roll bar or contract the fuselage to fit. It will take som muscle or a carefully controlled small jack, but opening the roll bar 1/4 should be possible.]

On 26 May 2009 at 13:19, Steven and Charissa Hild wrote:

>
> My finished "roll bar" came out overall ? inch too narrow. It fits in
> the attaches but, with a .125 spacer on either side.
>
> As I near the point of cutting and fitting the canopy, is this width
> discrepancy fatal to the canopy/roll bar fit?
>
> I?m asking now as I have gathered the part numbers for the replacement
> parts I?ll need to make this right.
>
> Thanks,
>
> Steven Hild
> Belen, NM
> RV-7, # 70289
 
Problem solved...

Thanks for the reply Steven. I did the same by contacting Van's Tech Support and received a response from Ken Scott as well. Basically, I used a hand pump hydraulic jack and a couple of 2x4 blocks and carefully/slowly spread the frame. I had to expand the frame a to a yield point (about 1.75 inches) before it would not spring back to the original starting point. I stopped when I got it to within 1/32nd on both sides. It simply amazes me just how much leeway there is in these airplanes
 
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