25-05 step 6 Aft Window

[Gagarin737]

I installed the aft window but it looks ugly. Between the screw holes the turtle skin "bulges". When the aft window was attached with clecoos I didn't see/notice it. At the rollbar the window fits perfect.
More builders with the same problem?
Any solutions?

Regards, Joeri.

 

[JBPILOT]

Over-tighten the screws maybe - -

Can you turn the screws with your bare fingers now ? They will crack the window if too tight.

John Bender

 

[Gagarin737]

They are not that loose. Try that tomorrow.

Thanks, Joeri.

 

[JBPILOT]

Hey Joeri - -

The ones on the 'roll-bar' should not be overly tight either. If the window can move tiny amounts, it is less likely to crack in my opinion. I think it will solve your other issue also.

John Bender

 

[Geico266]

It looks like you had the window on the outside of the skin when you drilled the window? You are going to have to get the skin to "relax" by either replacing the rear window or over sizing the aft holes in the window.

Let's us know how it turns out.

 

[MartySantic]

Oversizing the holes is a very good idea in both the rear window and the canopy (where screws are used).

 

[Gagarin737]

It looks like you had the window on the outside of the skin when you drilled the window?

The window was in the correct place.

Oversizing the holes is a very good idea in both the rear window and the canopy (where screws are used).

Marty, do you remember what drill size you used? (To much information in your blog, I can't find it )

 

[MartySantic]

I do not recall the exact size, BUT, I did use a unibit to enlarge all of the holes. (After reading all of the horror stories of enlarging any kind of hole with a normal or plexi bit). The unibit step I used was the next step larger than the hole size the plans suggested. I did not enlarge the holes on the canopy front bow where rivets are used. Think it was 5/32", which is close to a #23. Think Van's indicated a #27.

The hole size recommended by Van's gives you about 0.001" clearance between the screw and the plexiglass or lexan. IMHO, way too little to allow for expansion/contraction of the plexi. Van's should change the plans here to allow for the expansion/contraction.

 

[Gagarin737]

I'll give it a try with the unibit 4mm=5/32"

I also get the following advice via PM;

Your problem is likely cause by the window not being in proper position when the holes were drilled to the roll bar.
If you remove the screws on the sides of the roll bar and push aft on the window at this point, it will lift the window at the rear sides. This will make the window fit tighter to the inside surface of the skin and reduce the puckering (because the screws will not be attempting to pull the window to the skin).

At the moment it is 55F in my garage, I'll try it again when the temperature is going up.

Thanks all for the help, Joeri.

 

[GDS]

Our window/turtle deck fits the same way. The holes are oversized and the screws can be turned by hand. We eliminated those unsightly midriff bulges between fasteners, but end up with a ~3/16 gap on the curved portion. I filled it with silicone to prevent major water leakage. I saw an RV12 at Oshkosh on which the builder "broke" the edge on the curved part of the turtle deck. It looked great, I plan to do the same thing, but not until the window needs to be replaced.

 

[DonFromTX]

I had the same problem when I recently replaced my Ercoupe rear windows, they mount the same way as the 12. I drilled the holes the correct size by using the old window for pattern, and had the same effect you had. I too just used the unibit to step the holes to the next siza, it fit perfectly flat after that procedure. Seems to be some strange things going on unless you make the holes with more clearance.

 

[Gagarin737]

I saw an RV12 at Oshkosh on which the builder "broke" the edge on the curved part of the turtle deck.

I thought about that but was reticent/scared to break the edges.
I first try to enlarge the holes.

 

[joedallas]

I installed the aft window but it looks ugly. Between the screw holes the turtle skin "bulges". When the aft window was attached with clecoos I didn't see/notice it. At the rollbar the window fits perfect.
More builders with the same problem?
Any solutions?

Regards, Joeri.

From looking at the photos it looks like the back center of the window is to low
To check this remove all the screws accept the top center at the back and at the roll bar.
Then have someone press up at the back of the window from the inside (not to hard)
If a gap appeared at the bottom of the roll bar then that is probably the case.
The Skin is being pulled down by the window
By raising the back of the window will make the distance at the contact surface the same. (Skin to Window)
If this is the problem the holes need to be elogated toward the roll bar each one a little more
When installing the window the back of the window was a little low.

Take the screws out roll bar first, and then work your way back to see if the skin will lift the window.

Good luck