Sun May 23 2010

Canopy frame work

Here's one of the CS4-4 rivets with the mandrel removed so I can check the countersink depth. Note that I'm going to use solid rivets on the inside of both forward and aft curved sections, so the outside will get pop rivets on both forward and aft sections. My brother, Chris, made me up a bucking bar to allow bucking the rivets on the inside of the canopy frame. Thanks, Chris!

Here are all four canopy frame channels with the outer holes countersunk with a 120 degree countersink. I had intended to countersink these by hand, but the bit chattered terribly, so I had to use the countersink cage. It wasn't too bad actually. Here's what I did:

  1. Adjust the countersink cage on a piece of scrap to the nominal depth.
  2. Back off the countersink depth by 0.010 inch. This ensures that the holes along the curve don't get countersunk too much.
  3. Countersink all the holes.
  4. Check the depth of all the holes using the test rivet shown above. If the countersink depth is correct, put a checkmark next to that hole.
  5. Increase the depth of the countersink by 0.002 inch and re-countersink all the holes that don't already have a checkmark.
  6. Go to step #4

After switching to a 100 degree countersink, I did all the holes along the inside of the curve. The process was the same as for the outside, except I started with the nominal depth and increased it by 0.002 inch after each cycle.

Next, I got looking at the attachment of the F-632A center channel. I was surprised to find that the part didn't look quite like the drawing. Here's what the preview plans show for the attachment of the channel to the F-706 bulkhead.

...and here's the exploded view from the preview plans.

However, when I looked at the full sized plans, the design has changed. This drawing matches the parts supplied. Unfortunately I hadn't noticed this previously or I would have used AN426AD4 rivets where the forward turtledeck skin attaches to the F-706 bulkhead as shown here. Instead I used AN426AD3 rivets. I'm thinking of just leaving the 3/32 rivets or possibly using oops rivets. Maybe I'll call Van's to discuss.

Here's the exploded view from the full sized plans.

When test fitting the F-732A channel, I noticed it appeared the canopy rear window would be a tight fit between the channel and the F-774 forward turtle deck skin. In order to allow a bit more room, I elected to use a slightly thicker spacer (3/16 inch instead of 1/8 inch) for the F-732F plate. I used the prepunched holes in the channel to drill the spacer, so I should be able to return this part.

Here's the spacer with countersunk holes. The #30 holes attach to the channel only whereas the #40 holes attach to the skin and the channel.

I also fabricated these angle brackets for attachment of the forward end of the channel to the canopy frame.

On the aft sections of the canopy frame, the plans call for AN470AD4 rivets, but I decided to countersink the bottom two rows of rivets to accept AN426AD4 countersunk rivets. I did this because I'm going to add a cover plate to close up the channel and possibly mount some baggage lighting or map lights to the cover. I figured using flush rivets would look better and allow easier installation / removal of the cover. The top two rows of rivets are not countersunk and will receive universal head rivets per the plans. Note this picture shows the canopy frame upside down.