Canopy oversized Holes And Rubber Insert Technique

[FinnFlyer]

If you have the patience (doesn't take all that long with a 1/8" dremel bit), don't oversize the holes.

Expansion/contraction is mainly fore-aft.

Pick a stationary reference point. Then gradually increase the holes to a slot, bigger and bigger slots the further away from the reference point.

Example from my RV-4:
Alum: 12
Acrylic: 38
Diff: 26 micro inch/F
Elongate Slot width Elongate Slot width Ref temp Min temp Max temp
Position inches 160 80 -10 150
2.60E-05 Inch Inch mm mm More aft More forward
3 0.012 0.137 0.3 3.5 1.9 1.6
6 0.025 0.150 0.6 3.8 2.0 1.8
9 0.037 0.162 1.0 4.1 2.2 1.9
12 0.050 0.175 1.3 4.4 2.4 2.1
15 0.062 0.187 1.6 4.8 2.5 2.2
18 0.075 0.200 1.9 5.1 2.7 2.4
21 0.087 0.212 2.2 5.4 2.9 2.5
24 0.100 0.225 2.5 5.7 3.0 2.7
27 0.112 0.237 2.9 6.0 3.2 2.8
30 0.125 0.250 3.2 6.3 3.4 3.0
33 0.137 0.262 3.5 6.7 3.6 3.1
36 0.150 0.275 3.8 7.0 3.7 3.3
39 0.162 0.287 4.1 7.3 3.9 3.4
42 0.175 0.300 4.4 7.6 4.1 3.6
45 0.187 0.312 4.8 7.9 4.2 3.7
48 0.200 0.325 5.1 8.2 4.4 3.8
51 0.212 0.337 5.4 8.6 4.6 4.0
54 0.225 0.350 5.7 8.9 4.7 4.1
57 0.237 0.362 6.0 9.2 4.9 4.3
60 0.250 0.375 6.3 9.5 5.1 4.4
63 0.262 0.387 6.7 9.8 5.2 4.6
66 0.275 0.400 7.0 10.1 5.4 4.7
69 0.287 0.412 7.3 10.5 5.6 4.9
72 0.300 0.425 7.6 10.8 5.8 5.0
75 0.312 0.437 7.9 11.1 5.9 5.2
78 0.324 0.449 8.2 11.4 6.1 5.3
81 0.337 0.462 8.6 11.7 6.3 5.5
84 0.349 0.474 8.9 12.1 6.4 5.6

I can e-mail you the spreadsheet if you want.

Oh, and I found it easy to countersink the plexi for the dimpled side skins. Just slide the 1/8" microstop countersink back and forth in the slots.

Finn

[JoopSJ]

Originally Posted by mfleming

...

PS: I'm also thinking of Sikaflex but want to thoroughly explore all techniques before deciding.

Hi Michael,
I just finished glueing the canopy with SIKA.
It is very easy and clean and I can’t imagine going the route of holes, screws and Rivets.
B.t.w. Did we meet in 2017 during the Vans factory tour?

[F1Boss]

We have been using the oversize hole process on the Rocket canopies since 1994 or so. Many aircraft used that exact process too.

Drill the hole to match 1/4” OD fuel line, and cut the line to match the thickness of the plexi. Use tinnerrman washers and #6 screws to hold things in place - don’t tighten the screws totally. If need be, you can use a slightly longer piece of tubing as a shim if the plexi does not quite lay down on the tubing

Don’t use the attach screws to force the plexi to conform to the tubing if the plexi does not quite follow the tubing shape (under 1/16” or so), or as it was with clecoes.

Drill the plexi with a step-drill on low RPM.

Build up your normal fiberglass fairing between the windshield and slider, and along the aft & side skirts.

Use household exterior caulk of your color choice to waterproof the slider plexi along the side and aft fairings; attach with the suggested fasteners. Before final assy, lay a length of masking tape along the metal fairings to keep the caulk off of the exterior
Plexi.

Do not use silicon caulk - just the inexpensive water based stuff.

The caulk is amazing regarding how long it lasts. Never did hear of anything coming loose.

I have never heard of a Rocket canopy cracking when this process is used.

[mfleming]

Originally Posted by JoopSJ

Hi Michael,
I just finished glueing the canopy with SIKA.
It is very easy and clean and I can’t imagine going the route of holes, screws and Rivets.
B.t.w. Did we meet in 2017 during the Vans factory tour?

YES... I remember meeting at Van’s... glad to see you are building....good luck.

[PhatRV]

I would like to request pictures of this grommet technique. I read Danny King post but the pictures on tinypic are no longer there.

Thanks.