Hangar Flying => Hangar Flying => Topic started by: GlennBob on July 09, 2006, 11:26:23 PM
Title: Rear Pass. strake windows
Post by: GlennBob on July 09, 2006, 11:26:23 PM
Gentlemen, . . . Anybody have any tips on strake windows ? So my passenger can see something closer than a mile away over the strake ? I've seen some at the airshow, but not sure how to go about it or how to smoothly join the plexi to the bottom of the strake. Any hints ? I did a search but didn't find anything. Glennbob :wink:
Title: Rear Pass. strake windows
Post by: Waiter on July 10, 2006, 08:20:16 AM
I used 1/4 inch Lexan sheet, approx 9 x 12 inches. (Plexiglass should work OK also.
Look at photos on my site from about December 2004.
www.iflyez.com
The window location isn't critical. Mine are positioned about 2 inches in front of the fuel tank bulkhead, and about 2 inches out from the fuselage.
I can't remember the exact sequence, but it went something like this:
Before glassing the bottom strake outside surface, I marked the approx location where the window would go. When I glassed this surface, I added three layers of BID all the way around where the window would be installed. This adds a little more stifness for the lip that the window will sit in, and also helps transfer strake loads around the window.
With the outside skin of the bottom strake glassed (inside not glassed yet) I cut the window openings in the bottom of the strake approx 1/2 inches smaller than the window, all the way around. This provides the window with a 1/2 inch lip/frame, all the way around, to rest in.
From the inside, I created a "frame" by cutting away foam so the window would rest perfectly on the inside surface of the outer skin. The inside surface of the outer skin needs to be sanded so its a good bonding surface.
With the window temporarly laid into this frame, sand the inside surface of foam so it is even with the inside surface of the window.
Use duct tape as a release and mask the window (inside and out) so that 1/2 inch of the outer edge of the window is expose all the way around, on both the inside and out. This 1/2 lip will be the surface that gets bonded to the inside and outside skins.
Using 100 - 200 grit paper, carefully scratch this 1/2 inch lip all the way around, on both sides.
Do a final fit check of the window. Make sure the duct tape isn't caught between the window and the outer skin.
When ready to glass the inside of the strake: Coat the inside of the foam with micro like you would normally do. Wipe off any micro that gets into the window frame. Then recoat the entire frame lip (this is the inside surface of the outer skin that the window is going to rest on) with a very light film of epoxy. Now lay in a moderate layer of flox all the way around the on the lip.
Press the window into the frame opening, the flox will oozz out from the bottom and the top. Delay wiping off the bottom of the strake until your done with the layups. Make sure the flox fills any gaps between the window and the foam are filled. A very thin layer of epozy shoul extend onto the 1/2 inch window lip.
Lay up three layers of BID (2 or 3 inch wide) all the way around the window frame, so that it laps up and onto the 1/2 inch exposed lip of the window, and approximately 2 to 3 inches onto the surounding foam. Now lay up the normal number of layers inside the strake.
Place peel ply so it extends onto the window.
wipe excess flox from the bottom of the strake.
When you can do a good knife trim, (use a new blade) carefully trim to where the edge of the duct tape is on the window. Do not press down hard, as you do not want to run the knife into the window, as this would create a stress point that could later crack.
When the layups are cured, you should be able to remove the duct tape from both sides of the window, and have a perfectly framed window.
Waiter
Title: Re: Rear Pass. strake windows
Post by: GlennBob on April 12, 2011, 10:36:48 PM
Just found this post from Waiter, . .from the last time I asked this question. Looks like he frames the plexi in from both sides. I'm thinking I won't cover the outside edge of the plexi on the outside or bottom of the strake / window. I'm hoping to be as close to flush to the strake bottom as poss.