scsmith
Well Known Member
I am thinking ahead to a repeat offense. Premeditation, if you will.
I have a question about the shape and fit of the canopy on a fastback.
When I look at my standard canopy and look at the cross section at the station where the fastback canopy frame/skirt would attach at the back seat bulkhead, the standard canopy has, well to use a naval architecture term, tumblehome. This means that the canopy contour is wider up away from the bottom edge of the skirt, and is getting narrower along the bottom edge. Said another way, the canopy bulges out beyond the skirt.
The Showplanes website says their kit uses a standard canopy, yet the shape of the bulkhead at the rear seat back does not fit this tumblehome shape. It is widest at the bottom, and has a normal oval shape.
So, it would seem that fitting a standard canopy to the fastback skirt and fuselage shape would require flexing the canopy to fit that shape. This concerns me because it puts a bunch of pre-stress into the canopy.
When I fit my standard canopy, I took care to shape the canopy frame so that it fits the canopy in its completely relaxed state - no built-in stresses. That plus Sikaflex and I think/hope it will never crack. I would be really worried that forcing the canopy into a different shape would be asking for trouble.
Thoughts? DanH? Scard? Scott Hersha? Others?
I have a question about the shape and fit of the canopy on a fastback.
When I look at my standard canopy and look at the cross section at the station where the fastback canopy frame/skirt would attach at the back seat bulkhead, the standard canopy has, well to use a naval architecture term, tumblehome. This means that the canopy contour is wider up away from the bottom edge of the skirt, and is getting narrower along the bottom edge. Said another way, the canopy bulges out beyond the skirt.
The Showplanes website says their kit uses a standard canopy, yet the shape of the bulkhead at the rear seat back does not fit this tumblehome shape. It is widest at the bottom, and has a normal oval shape.
So, it would seem that fitting a standard canopy to the fastback skirt and fuselage shape would require flexing the canopy to fit that shape. This concerns me because it puts a bunch of pre-stress into the canopy.
When I fit my standard canopy, I took care to shape the canopy frame so that it fits the canopy in its completely relaxed state - no built-in stresses. That plus Sikaflex and I think/hope it will never crack. I would be really worried that forcing the canopy into a different shape would be asking for trouble.
Thoughts? DanH? Scard? Scott Hersha? Others?