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Old 07-01-2018, 04:45 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 1,846
Default Canopy drilling

The issue I've found with drilling the canopy to canopy frame holes is making sure you drill at exactly the right place on the frame to avoid unnecessary stress on the glass.

For the first project (8A) I copied a trick to find the exact tangent point between the canopy glass and the steel frame. After running some standard masking tape very lightly on the frame, the canopy is carefully put in placed and clamped. The result is a perfect line in the tape where the glass touched the frame - the tangent point.

I found out the trick does not work with powder coated frames (first plane was pre-powder coating). There is not enough color contrast between the powder coat and the tape to see the line. The fix was to first run black electrical tape on the frame, and the masking tape on top of that.

The photos show the clear tangent line. Note that the tangent line is not at the horizontal midpoint - the glass curves under.

Next steps:

- With the glass off, use a sharpie to mark the line and then space out where the holes will go.
- Drill the #40 holes in the frame.
- Put the glass back on, check position a few hundred times then drill through the glass into the #40 holes. Clecko.
- Take the glass off and using a unibit drill the glass holes to 1/4" and slightly countersink the outside (more for the canopy bow than the sides as the sides have the fiberglass skirt that gets countersunk for the tinnermans). The objective is for a tinnerman to fit into the glass and then the CS4-4 rivet to fit into the tinnerman - the tinnerman spreads out the attachment force.
- Drill the frame #40 holes to #30.
- The roll bar gets tapped for #6 screws per the plans, but tinnermans again used under the screws on the glass.
- If you hate the powered coat color as much as I do, remove the frame and roll bar for final paint. Reassemble after the rest of the interior is painted.

Have fun,

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Old 07-01-2018, 06:47 PM
Champ's Avatar
Champ Champ is offline
Join Date: Apr 2012
Location: Kingsville, Ontario, Canada
Posts: 227

Itís been a while but used a trick I probably got on VAF. I Applied a thin film of oil on the canopy frame then set the canopy on the frame. Oil showed a perfect line at the tangent point.
Dennis Enns
Kingsville, ON
Bellanca Champ 7ACA since 1986, restored 1990.
RV-8 IO375, Hartzell CS, dual PMags.
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