Sweating bullets on this one

I would really like to check with you guys before I do this next step.

My RV-8 Canopy frame sits a good 3" above the rail. The plans call for it to be only a 3/4" to 5/8" gap. That is a lot of bending, and I am having a hard time believing that the rail won't bend in a single location, and possibly crack.

Is that a normal amount to have to remove? I'm trying to figure out why they make them so far off in this case. The other adjustments were very minor compared to this. Is their any special technique to minimize the risk of destroying the frame?

cdeerinck said:

I would really like to check with you guys before I do this next step.

My RV-8 Canopy frame sits a good 3" above the rail. The plans call for it to be only a 3/4" to 5/8" gap. That is a lot of bending, and I am having a hard time believing that the rail won't bend in a single location, and possibly crack.

Is that a normal amount to have to remove? I'm trying to figure out why they make them so far off in this case. The other adjustments were very minor compared to this. Is their any special technique to minimize the risk of destroying the frame?

Click to expand...

It's hard to say if this is a big problem from looking at your picture, but it looks to me like the slider frame isn't in the fully closed position. When the the canopy is fully closed, the rear "cross bow" should be just slightly above the turtle deck "approximately 1/2" or so from memory) and the rear pin assembyl sits down into the "pocket" in theturtle deck right behind the rear seat back. When this portion is all the way in the close position, the rear most part of the frame should be much lower than your picture shows. At that point, it may still require a bit of adjustment to meet the plans dimension.

Skylor
RV-8

Similar to mine

My canopy frame exhibited a similar position at initial fitting. I placed it on blocks and incrementally bent it down to the proper position without difficulty.

Sweating bullets - canopy

Put the slide rail in and the UHMW block that the frame seats in, then check that the front bow if the canopy frame is aligned with the roll bar in front a little to the high side and your gap at the rear should be less. As someone already said, make sure the frame is bottomed in the UHMW block so the frame sets down close to the top skin at the rear seat bulkhead. May still require some minor bending. The front of the frame may need to be raised up on the front rollers slightly for proper alignment. I believe it may mention that in the build manual, or used to anyway.
This is just one of those places on the 8 that typically doesn't fit perfect out of the box but still so much better than building the canopy frame from scratch.
Good luck,

Long story, short.

This subject could be a long drawn out one. I can tell you that after looking at a lot of RV-8's on the ramp, that no two are the same with respect to the canopy to frame fit. It is good that you are fretting this part of your build, the canopy is a high dollar item and takes a long time to replace if you crack it, too badly. In this case I can only tell you to go very slow. Fit, bend. fit bend, look and form to fit little by little. This is one of those items where you need to be an artist more than a machinist. Slowly get your curves of the frame to fit the canopy itself and keep in mind the skits have to fall off that outside curve of the canopy to match with the skin of the airframe. Your doing fine, just fine. Yours as always, R.E.A. III #80888

I was there a few weeks ago and just as Skyflyer I bent the frame down with no problems. Just watch that the bend will not be in one place only - anyhow it will not be seen later as it will be covered with the skirts.

I have not seen an 8 yet that did not require a little bit of help by bending this down.

Bend Away!
BUT! when fitting the canopy, be careful the prevent stress risers in the plexiglas.
Look at Skylor's picture, where the frame cross bow, diagonal frame member and the step to smaller diameter tube can all create a contact point that 'might' touch the plexiglas canopy. These seem to be the locations of many RV-4 and RV-8 canopy cracks. I know, mine cracked at the diagonal weld last week. Straight up, & more than 1/3 of the way across the canopy!
I'm not certain why it cracked, poor edge polishing of the plexi, or a stress riser?
Or if it was from sitting in the sun or running up to Vne? Or too much pulling force from the canopy latch distorting the frame?
It doesn't really matter why for me now. I just need to fix it.
1st plan, glue it in place with Acrifix 1R 0192.
2nd plan, if 1st plan fails, groove out the crack and fill with PlastiFix.
3rd plan, if 2nd plan fails, use Cut Off Wheel to cut canopy symmetrically across to the same point on the opposite side to fully stress relieve the canopy tail, lay a fiberglass 'Targa' strip over packing tape, then pull the 'Targa' finish it and bond it in place with SIKA.

Sorry for the delayed response. I thought I subscribed to this thread, but I never got any notifications that anyone had replied.

For clarification, the frame as shown already is fully closed, and the rear bow is very close to the skin. I never really had any doubt that I need to bend the farme down. My concern is that I do it in the right manner.

There is a note on the plans that said the frame cannot withstand a sudden bend near the weld, as it will crack the weld.

My question was meant to ask on any specific techniques that I can use to make sure the bend doesn't get focused on a single area, or how to make sure the bend doesn't occur where the welds are.

Skyflyer mentioned he "put it on blocks". Anything specific? Is the a detent in the blocks to avoid the weld? Where are the blocks positioned? Anything else?

All better

Thanks for the confidence injection guys, it's all good now.
Sorry for the bad lighting in the picture.

Glad you solved that one ...looks good . Good luck and take care with the plexiglass fitting. I Sikaflex-ed it and glad I did

Looks good

Nice work on that frame.

Good luck and take care with the plexiglass fitting.

I Sikaflex-ed it and glad I did

Click to expand...

I went with Van's stock and I am glad I did