macrafic
Well Known Member
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!!!!
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!!!!