[macrafic]

I have just about completed final trim of the canopy for my 7A. Just have the sides to trim up for fitting to the canopy side rails and I am pleased as punch with the fit! 1/8" Sika spacers all the way around the roll bar and side rails; 1/16" spacers along the front, between the canopy and the canopy skin. Thanks to Twin Cities VAF chapter member Jim Fogarty for his phone conversations, emails and overall encouragement to get me through the cutting/trimming/etc.!

In looking ahead to the Sika process, I have some very specific questions. Jim did not Sika his canopy, so if somebody wants to be a "mentor" for the process, by phone/email, please contact me privately. In the meantime, I am hoping for some answers to the following.

1. Many forum posts talk about "tacking" the canopy initially, then going back a day or two later and filling in/filleting the final product. Yet, I keep reading about the fact that the adhesive must be applied within 2 hours of the primer being applied. I am confused about this. Do you re-apply the primer when you go back later? Or, is the primer from a day or two before still good?
2. Once the canopy is tacked in place and cures for a day, can the canopy be removed from the aircraft and the rest of the Sika process (fill in, fillet, etc) be completed on the bench? Any downside to this? Sure would be easier to work on the bench.
3. Where the aft (stationary) part of the canopy fits under the aft top skin, dead center, there is no room for 1/8" of Sika (or much at all). Do you simply skip this 2-3" when you apply the adhesive between the aft top skin and the rear canopy?
4. Similar to question 2 above, where the aft stationary canopy fits between the roll bar and the top aft skin, along the sides, there is very little room for more than the canopy itself. Do you just skip this couple of inches with the adhesive, tapering the Sika down from 1/8" to zero as it comes down the side of the roll bar?
5. Since the rear canopy can't fit the 1/8" Sika either at the top or at the rol bar sides relative to the aft top skin (see above 2 questions), are people still trying to achieve 1/8" along the rest of the skin, or going with a much thinner layer?
6. I have my canopy side rails fit so that the skirts will fit exactly even with my fuselage side skins, per Van's instructions. However, 1/8" of Sika between the side rails and the canopy will push out the side skirts 1/8", no longer allowing them to line up with the fuselage side skins. To make matters worse, adding another 1/8" of Sika between the canopy and the skirts, should I choose to Sika the skirts to the canopy, will puts the skirts out another 1/8". How did you handle this? Did you allow your skirts to overlap the fuselage side skins, using spacers where necessary? Something else?
7. Finally, per the plans, the aft bottom corners of the tilt canopy are designed to fit between the roll bar and aft top skins, when the canopy is closed. Given the lack of stability in the tip-up, this seems to me like a natural place to catch the corner of the canopy and crack it. I see some create an inside corner so the canopy does not need to fit there. I don't like this option as an inside corner also seems like a good place to create stress. I see one post of a builder who did the 45 degree thing, covered by a targa strip so it is not visible from the outside. This seems like the best solution to me. Any other ideas builders have used here?

Thanks, from someone trying to finish this proces while the weather is still relatively warm in Minnesota!!!!

 

[RV7A Flyer]

7. Finally, per the plans, the aft bottom corners of the tilt canopy are designed to fit between the roll bar and aft top skins, when the canopy is closed. Given the lack of stability in the tip-up, this seems to me like a natural place to catch the corner of the canopy and crack it. I see some create an inside corner so the canopy does not need to fit there. I don't like this option as an inside corner also seems like a good place to create stress. I see one post of a builder who did the 45 degree thing, covered by a targa strip so it is not visible from the outside. This seems like the best solution to me. Any other ideas builders have used here?

These work great:

http://www.bullerent.com/CanopyGuide.htm

 

[sahrens]

PM sent

PM and email sent with my contact information.

 

[bruceh]

I documented my sika flex install here. You can come back within 24 hours and finish off the gaps in the sika flex. You'll want to get 90% or more done in the first pass. Once that sets up it isn't moving around. Taking the canopy off and doing a finishing pass to clean up the look of the edges is easy and you can fill in any tiny gaps left from the spacers. Trying to fill in much more than that is difficult with the caulking gun.

I tapered the sides down from the top of the roll bar with 1/8" spacers to almost flush with the side skirts. I used some 1/32" monofiliment nylon line as a spacer to make sure that I still had some underlying space between the canopy and skins on the sides and back where the rear window tucks under the top skins.

It came out great and was much easier than you think it will be. The canopy bubble does expand quite a bit when the airplane sits out in the full summer sun. I had to come back and sand down the gap between the canopy and the rear window to a bit more than Van's has on the plans.

 

[rv7charlie]

I did the same thing, tapering from 1/8" on top of the rear bow (at roll bar) to tight against the frame at the longeron. Wish I'd thought of the fishing line trick. I installed the back glass with just a thin layer of sika between plexi & skin, & a bead of sika spanning between the edge of the plexi & the skin.

Not flying yet, so no long term data.

 

[sahrens]

Sika application

I

1. Many forum posts talk about "tacking" the canopy initially

2. Once the canopy is tacked in place and cures for a day, can the canopy be removed from the aircraft

3. Where the aft (stationary) part of the canopy fits under the aft top skin, dead center, there is no room for 1/8" of Sika (or much at all).

4. Similar to question 2 above, where the aft stationary canopy fits between the roll bar and the top aft skin, along the sides, there is very little room for more than the canopy itself. Do you just skip this couple of inches with the adhesive, tapering the Sika down from 1/8" to zero as it comes down the side of the roll bar?

5. Since the rear canopy can't fit the 1/8" Sika either at the top or at the rol bar sides relative to the aft top skin (see above 2 questions), are people still trying to achieve 1/8" along the rest of the skin, or going with a much thinner layer?

6. I have my canopy side rails fit so that the skirts will fit exactly even with my fuselage side skins, per Van's instructions. However, 1/8" of Sika between the side rails and the canopy will push out the side skirts 1/8", no longer allowing them to line up with the fuselage side skins.
How did you handle this?

7. Finally, per the plans, the aft bottom corners of the tilt canopy are designed to fit between the roll bar and aft top skins, when the canopy is closed. Given the lack of stability in the tip-up, this seems to me like a natural place to catch the corner of the canopy and crack it. I see some create an inside corner so the canopy does not need to fit there. I don't like this option as an inside corner also seems like a good place to create stress.
Any other ideas builders have used here?

1. I did not "tack" the canopy. I laid down a bead along the front edge and the aft edge. I used tongue depressors under the leading edge to maintain the clearance. After several hours I pulled the depressors out and filled those in the next day.

2. I did not wait a full day until I pulled the canopy, just over night. I did the initial application around 2:00PM and pulled the canopy the next morning. It was much easier to work on the bench. After finishing I let it set for a week without moving it. Probably do not need to wait that long, but I did.

3. I applied enough sika to ensure a tight seal. In order for it to come out the leading edge at the roll bar must separate first. Even then the canopy will break as the wind will force it toward the rear of the aircraft.

4. I am not sure I understand your question. I believe you are asking for the width of the sika along the sides of the roll bar at the rear canopy. I tried to maintain an 1/8" but was more concerned about the alignment with the forward canopy. If that does not answer your question, send it again and I will try again.

5. I believe you are asking about the sides where the aft canopy meets the inside of the fuselage. I tried to ensure a nice even consistent application. You are probably not going to get 1/8" here.

6. I applied sika on the outside of the canopy and the inside of the skirts and clecoed them inplace. There is not 1/8" here.

7. I installed the guides an earlier poster mentioned. I also sanded a radius at the bottom corner of the canopy. These two items seems to make it easier to close the canopy without banging the corners into the roll bar. Time will tell.

It is my understanding the 1/8" is recommended for marine window applications were the windows are as large as 8'x10'. This thicker application is to assist in the expansion of the large flat surface. Our canopies will expand multidirectional so the amount of change at the Sikaflex is less. That is not to say you should ignore the 1/8" recommendation, but there are locations you won't get it. The aft canopy is a good example.

Hope this helps.