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In flight window loss

Replaced

Well,I got my window installed and ended up using the Weldon from Vans. It is just as bad to work with as described. Was going to use Lord,but Aerosport was out of stock and could not give me a definite date when they would have it. I wanted to get flying sooner that that. Used Vans window vs Cee Baileys b/c Vans is .150 and Cee Bailey says their side glass is .125 But the trimming is time consuming for sure! Now I am putting on my flame suit,but I have decided to put c/s #6 screws in the corners of All my windows with nylock nuts on the inside so that I will only lightly snug them. I have a full Flightline interior and the "rope" trim will cover the nuts. Experimented with the remaining parts of the old window as well as the cutoff parts of the new window and it works quite well. Gonna glass over it anyway so I like the belt,suspenders & elastic waistband! Flame if you choose but if you haven't lost a window in flight,turn down the heat just a bit. This is why they call it experimental,right? Just thought I would relay "the rest of the story"
ps;Vans tech support didn't see anything wrong with my plan,thought it sounded feasible.
 
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Your choice on adding the screws, but if you do take steps to mitigate possible crack issues by:
- Use a Unibit to oversize the glass screw holes to something like 3/16?.
- Countersink the holes to accept a #6 tinnerman.
- Glass over the screws and tinnermans as you suggest.

The objective here is to have the tinnerman spread out the screw clamp pressure over the edge of the hole, and the screw does not touch the glass so you avoid creating a hot spot.

This process worked well on RV-8 and 8A canopy glass.

That said - I offer that adding the glass over the outside as I discusses should be more than enough to let you sleep at night. But - your plane so build it like you want.

Carl
 
My experimenting has definitely been with holes larger than required for a #6,but not as large as 3/16ths. Wasn't planning on tinnermans though. On the scraps I countersunk to where the screw head is slightly below flush to allow for sanding the plexi down for glassing. I wasn't planning to have any tension on the screw at all,just engaged in the nylock and still able to rotate fairly easily. More of a backup safety device. But I listen to all input and welcome it.
 
49clipper

Which Weld-on are you planning to use? #40, or other? I am about to do a windshield on my build (not RV) and have decided on Sika-flex 295UV due to the fact that Weld-on looks like it could be a real PITA. Saw a lot of comments on how hard the process and mixing is. Comments?
 
Offering this tidbit up. Beech Muskeeters have bonded side windows that were done with proseal. The 56 year old airplane in my hangar I'm doing an annual on shows no sign of delamination.
 
I used Weld-on 10 from Van's,Aerosport was out of the Lord adhesive that I would have much preferred but they didn't know when it would be back in stock.
I can confirm Weld-on is a pain to work with. Stringy and at least in Tx summer temps,a very short working time. But got it done. Didn't find mixing it to be difficult though.

I bet Muskateer windows have never been subjected to the lift generated at 200 mph! 😂
 
Which Weld-on are you planning to use? #40, or other? I am about to do a windshield on my build (not RV) and have decided on Sika-flex 295UV due to the fact that Weld-on looks like it could be a real PITA. Saw a lot of comments on how hard the process and mixing is. Comments?

I used sika. Very secure, but you need a plan to deal with the expansion and contraction. The sila bulges when the window expanda and creares a valley when the window contracts. Must changes happen at the two front corner and the rear arc. I wish i had taken the time to clean up the joggle edges and did what Jan did. I have the old green top and the workmanship was horrific. I used a flexible bondo instead. Not bad, but the bulging would be less noticeable with the black accent

One of the reasons it is so secure is that the adhesive flexes and conforms. With a ridgid adhesive loke weldon, the glue joint is taking all of the stress from the expanding plexi. Any weakness ther and it will snap loose like the op saw.
 
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I used Weld-on 10 from Van's,Aerosport was out of the Lord adhesive that I would have much preferred but they didn't know when it would be back in stock.
I can confirm Weld-on is a pain to work with. Stringy and at least in Tx summer temps,a very short working time. But got it done. Didn't find mixing it to be difficult though.

I bet Muskateer windows have never been subjected to the lift generated at 200 mph! ��

As you noticed, the force on the window in flight is minimal. The stress on the joint is from the difference in expansion rates, in my opinion. I believe that baking on the ramp is the real evil here.
 
Maybe I said something confusing but no,I don't think the force in flight is minimal,I think there is quite a bit of lifting force on the side windows in flight. As there is on the doors. But I agree with you that heat on the ramp leads to the cracking in the paint from the different expansion of Plexiglass to fiberglass.
 
I had a similar problem

About 2 years ago, I noticed the my back windows were separating and debonding from the canopy. Thank goodness I had the foresight to recognize that this can separate and I had the windows removed rebonded , fiberglassed and painted by a guy with lots of experience in fiberglass. I did not build my 10, so I wanted to get someone with experience. Sorry you had to go thru this scary experience, but I must say I?m proud of myself for recognizing this and being pro active about it.

Ted Chipps
Rv10 498EC
 
That's a bit different than my situation. I had the expansion/contraction cracks at the corners but no separation or debonding that was apparent until the window departed. The cracks were the same as they had been for the 5 years I have owned it. No difference in height with the surrounding fiberglass or widening of the cracks over the years. But I'm glad you saw yours debonding and got them fixed!
 
Does your RV-10 have optional additional NACA vents?

Thank you for sharing your experience. It makes us all safer and more aware.

I was wondering if your RV-10 has the optional NACA vents folks are putting on the sides of the tail-cone for additional cabin airflow?

Thanks
 
I'm glad to see this event had a positive outcome - well done!

I come from another "brand" of aircraft, Glasair. If one does a search on youtube one will find a series of videos posted by Zach Chase of Fibertech Composites in which he details the installation methods used to install windows in the Glastar and Sportsman aircraft. He is a detail-oriented guy and the method which he pioneered has proven highly successful and has been adopted by the Glasair factory.

The material used in installing the windows is also used for the installation of windows in skyscrapers - Silpruf SC2000. It has very little strength in a thin film but has tremendous strength in a thick film. It does not require the use of primers or other bonding-prep agents. The only caveat is the product has a definite shelf life (12 months) and one wants to ensure one acquires product which is fresh.

The experience in the Glastar/Sportsman fleet using the Silpruf method has been excellent. I am aware of one bond failure - the builder conducted an analysis and concluded his Silpruf material was right at its expiry date when he installed the window. The experiences of other builders has been that window removal can only be accomplished through the use of an .020" safety wire "rope saw" to slice through the Silpruf bond.

It is my understanding that several RV builders have successfully used Silpruf to install their windows and canopies.

I provide this information merely to expand the list of available options for window bonding in the RV line of aircraft - I can't say any one technique is better than any other. I know from personal experience that my Sportsman windows were installed using Silpruf and Zach Chase's methods and the final result looks like the airplane rolled out of the Gulfstream factory rather than a homebuilders basement or garage - I am completely satisfied with the finished product.
 
I am also a believer that the large differences in the thermal expansion rates of the plexi vs F/G requires an adhesive that provides some flex to support those differences. Think the world of Van's but believe they got it wrong in specifying the weld on adhesive. It is simply too rigid with very little give for this application. Even the Weld on tech said it was a bad fit and recommended a different adhesive that was more flexible. Instead, look to the marine industry that regularly adheres plexi windows into F/G frames/structures.

I used sika 290 (the gold standard in marine window adhesive) and you wouldn't believe the amount of expansion and contraction that I have observed in the seams (goes from aggressively concave in cold to aggressively convex in heat). If that were rigid adhesive, every event would be trying to shear the adhesive off. No wonder we have seen the windows depart unless the bond is near pefect.

Larry
 
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