What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Help - Windscreen Intimidation!

[email protected]

Well Known Member
Well, this is the last major step in my RV-7 build and it seems I've been on my heels a bit. After finally jumping all in yesterday and drilling the windscreen, it wasn't as bad as I thought it would be (seems like most of this ~5-year build has been like that).

You can see from my pictures I have about 1/2" to 5/8" separation/outward bow of the plexi from the fuselage on the lower sides. I think this is somewhat normal.

Can someone point me to a picture or provide a description of how they used a clip to pull this in tight? Seems like a lot of stress will be concentrated in this area if I pull it in tight; but I need to pull it in, right? Can this be re-shaped with a heat gun? Maybe this is not a big deal to simply pull it in tight. Edges are finish-sanded smoothly.

Any help would be much appreciated. Thanks!
Ryan
 

Attachments

  • Windscreen #1.jpg
    Windscreen #1.jpg
    202.3 KB · Views: 258
  • Windscreen #2.jpg
    Windscreen #2.jpg
    343.8 KB · Views: 278
Windshield

I had a little spread at the bottom aft corners. Mine is bonded with Sika so the windshield was held in place by boards till it cured. After cure, I put one clip either side and another just a bit forward. Watch the roll bar weldment. Rivets may not fit. I had to put the aft clip forward of the roll bar weldment.
Be very careful about heating. I wouldn't.
 
Thank you for the good info Larry!

I won't try heat. On both sides of the lower portion that runs parallel to the fuselage is a span of about 12-13 inches that bows out. If I place one clip approximately in the center of this span, then I think that would do it. There is a small tendency for the upper portion to lift from the skin when I press down on the plexi from the sides where the clips would go, so I may also place a clip on either side of centerline near the top, just to keep the plexi from wanting to rise off the forward top skin.

Ryan
 
I used sika to bond my windshield. I held down those splayed corners with scraps of balsawood temporarily cyanoacrylated to the metal, and then shimmed tight.

Stewart Willoughby, 6 final assembly
 

Attachments

  • 20220424_163022.jpg
    20220424_163022.jpg
    452.3 KB · Views: 282
Relief

I had a lot of stress/force to pull my sides in on my RV9A (same fuse as a 7).
I ended up changing the radius on the lower windscreen that transitions from the front top to the left (or right) side. For me this is what was holding it out.
In other words, I carefully trimmed the lower curve a little at a time to allow the sides to pull in better/easier. With sikaflex, I think it is more forgiving since sika will tolerate a 1/4" gap or so when bonding. I ended up only using one clip on each side to hold the sides in while the bonding dried.

In looking at your picture, your radius appears way sharper than mine. Here is a picture of mine for comparison.
 

Attachments

  • CB307F6E-15A8-4A63-BAFE-70B7CA203EB0.jpg
    CB307F6E-15A8-4A63-BAFE-70B7CA203EB0.jpg
    390.9 KB · Views: 246
Last edited:
Very timely, I’m Sika bonding my windshield this week and have the same issue with the bottom corners. Thanks for the tips!
 
Line

The line between the windscreen and fuselage top piece seems to follow a curve one would get if a plane intersected the top of the fuselage at about 45degrees. There was a guy who made a metal fairing, and this only works if the intersection is a line formed by a plane intersecting the fuse top, if you understand what I mean.
 
The line between the windscreen and fuselage top piece seems to follow a curve one would get if a plane intersected the top of the fuselage at about 45degrees. There was a guy who made a metal fairing, and this only works if the intersection is a line formed by a plane intersecting the fuse top, if you understand what I mean.

Like the line that would be made by a laser level if it was projected down from the top of the roll bar? Do you think that would work to help with trimming and fitting?
 
Don't overthink it too much. I used a clip but tried to minimize the pressure on the plexi. I could not get both sides to match, but a lot of that will be hidden by the fiberglass work on the transition.
 

Attachments

  • _20220425_072200.jpg
    _20220425_072200.jpg
    306.9 KB · Views: 178
  • _20220425_072246.jpg
    _20220425_072246.jpg
    235.8 KB · Views: 183
Andrew,
QQ, did you Sika bond yours? If yes did you bond to both the roll bar and the fuselage? I'm thinking I do both and was planning on several clips to help secure and align the windshield while setting up. Thanks.
 
I think I added an additional screw or two with different size nylon washers to move the plexi away from the roll bar and stabilize the bottom aft end of the windscreen, to make it stable for the fiberglass wrap. I don't have a picture of my plane. The attached picture is of the Van's RV-9A demonstrator at OSH in 2005, showing how the aft end of the windscreen blends into the side of the plane. Van's added some kind of filler to cover the gap after the windscreen fairing was done.
 

Attachments

  • OSH 035.jpg
    OSH 035.jpg
    296.5 KB · Views: 140
Trim and Sika

So i trimmed the lower end of my windscreen so a 3/32” cleco held the windscreen against the side of fuse. The trimming mainly was around the area where the top skin turns down the sides. After the sika was set for a few days, I removed the clips and will plug the holes on the inside and touch of paint.
 
No

Like the line that would be made by a laser level if it was projected down from the top of the roll bar? Do you think that would work to help with trimming and fitting?
No the line would be formed by a laser level mounted over the engine. ( 90 degrees to what you mentioned above)
 
Plan

So i trimmed the windscreen and bonded it to the plane using sikaflex.
Now I am working on the fiberglass.
I put packing tape down and made the tape tight across the gaps so it makes a smooth transition for the first layer of glass.
The first layer of glass will use black dye I got from the aviation aisle of Hobby Lobby.
The rest of the layers will use normal fiberglass.
I have elctrical tape on there so i can peel it off before it sets to make a nice edge line, but I am think that will be too hard to do. I think I will lay up the glass as close as possible to the tape edge, and error on the side of a little overhang if it is not perfect.
The glass cloth is all cut, should be putting the first layers down this week.
Once all done, i will pop off the fiberglass, remove the tape, trim and glue on with sika.
No snading the fiberglass on the plane.
Wish me luck
 
Andrew,
QQ, did you Sika bond yours? If yes did you bond to both the roll bar and the fuselage? I'm thinking I do both and was planning on several clips to help secure and align the windshield while setting up. Thanks.

No Sika, I used the traditional plans method. There is nothing between the roll bar and the plexi, just a lot of care used in drilling and enlarging the screw holes. [Edit: upon reflection, that's not entirely true, I placed a few nylon washers from the Aviation Aisle at Lowes at the lower ends of the roll bar. I think I was following someone else's build log on that recommendation to prevent stressing the plexi too hard.] The gap between the windshield and forward fuselage is filled with an epoxy/micro slurry tinted black and is basically invisible against the glareshield.
 
Last edited:
I sure appreciate everybody's response to my original question and those who provided some pictures of how the clip works!

It seems that Van's recently provided a step-by-step video of their process and use of clips. I'll go back and re-watch those. If I'm not mistaken, those clips became a permanent part of (imbedded into) the fiberglass lay-up.

I'm not sure of the advantages of bonding with Sika (I'll do some research here). I'm assuming that over the roll-bar area, folks have chosen to either bond with Sika, or drill and tap for screws. Are there advantages to doing both? The forward portion of the windscreen would still need the fiberglass layup for the smooth transition anyway, correct?

I have no experience with Sika, but I was able to carefully drill and enlarge the slider-portion of the plexi and attach as per plans.

Thanks again All!

Ryan
 
I sure appreciate everybody's response to my original question and those who provided some pictures of how the clip works!

It seems that Van's recently provided a step-by-step video of their process and use of clips. I'll go back and re-watch those. If I'm not mistaken, those clips became a permanent part of (imbedded into) the fiberglass lay-up.

Yes. They are held on with pop rivets, which fall forward of the panel area, so they won't be seen from the interior unless you're looking up from the footwell. Then they are buried under the transition fiberglass.

On another note, due to the nature of how the plexi is formed in the mold, I could not get the windscreen to line up perfectly centerline of plexi to centerline of aircraft without it sticking out on the side worse than if I let it sit a bit crooked. Go for best overall fit. I doubt you would notice the slight right side bulge now looking at the finished aircraft unless you were using a laser line. Making small trims at the bottom to eliminate contact with the fuse can change how it sits relative to the fuselage so if you aren't happy you can keep working on it, but beware it is possible to overdo it and end up without enough plexi and too big a gap to bridge. Only you will know if it isn't perfectly symmetrical in the end, so don't let the big picture get lost and perfection become the enemy of completion. Good luck!
 
Last edited:
Back
Top