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prkaye

Well Known Member
My biggest air drafts in my canopy are through gaps where the side-skirts don't quite sit flush with the sideskin when the canopy is closed. Looking down behind the canopy rail (between the canopy rail and the sideskirt) there is quite a visible air gap. I tried putting some self-adhesive foam weather-stripping on the inside of the sideskirt, but as soon as I opened the canopy this got caught, wedged and pulled away, because the curved contour of the sideskirt changes in relation to the fuselage and the canopy rail as the canopy is slide forward or back.
How have you guys managed to get a nice tight seal here? Or is it too late now that my plane is totally finished and painted and i'm not about to start bending my sideskirts to fit tighter?
 
The easy way is to slit a piece of foam pipe wrap lengthwise and drop it in the slot between your canopy rails and the canopy skirts after you close the canopy. It sucks right down into the gap in flight and seals things very well. You need to remember to remove it before you open the canopy, or it may get blown across the ramp by the prop blast.

A V-shaped piece of rubber with one leg glued to the side skirt and the other leg free to suck down into the gap *might* be a better, more permanant solution. But the pipe insulation does just fine for me on the 10 days a year my cockpit would be too cold otherwise.
 
OK, This works

prkye, when you open and close your canopy you notice the there is NO NATURAL parallel surfaces between the fuselage and the canopy skirts through the full travel of the canopy. The solution involves creating them. I submitted it several years ago and it was published in the RVator but the author (Ken Scott I believe) did not understand the fundamental design and got it wrong in his description! It is also in this forum in at least one thread (one started by Ricka I believe).

First I have no skirt overlap of the fuselage skin - the bottom edge is parallel with the plane of the canopy deck when fully closed.

Is there a surface in the fuselage that is parallel with the direction of travel of the canopy? Well yes there is - it is the curved outer surface of the extrusion (track?) on the left and the right canopy deck.

Now, if you added a structural member (rib) to the canopy side skirts with a surface parallel to the outer surface of the extrusion you would have a starting point for creating seals in the area of concern.

I made my ribs out of 3/16" aluminum bar stock bought from Aircraft Spruce. It takes some patience but It can be done with precision. I marked off the canopy decks outboard of the tracks in 1/2" increments. Then I measured the horizontal distance from the outer surface of the track to the side of the fuselage at every mark and recorded them with the distance of the associated mark from the front of the deck. Next I made a pattern out of file folder material (cardboard) with a straight edge and perpendicular marks at 1/2" increments and ... this get tedious so I'm going to cut it short. Layout the non-straight edge on the bar stock with respect to the straight edge using the pattern. Then I sawed out the two ribs using a hack saw (now I have a band saw and it would go much faster) and finish the sawed edge so that it fits nicely inside the canopy skirt at a location above the canopy deck that is the same as the height of the maximum width of the extrusion (track). Match drill the skirts and the ribs, dimple the holes in the skirts, countersink both ends of the holes in the ribs, double flush rivet the ribs to the skirts. Use the patterns created earlier to make oversized seals out of rubber sheet. Glue the seals to the bottom of the metal ribs with 3M yellow weather strip adhesive. They are below the maximum lateral extension of the extrusion blah blah blah. I also have some 1/16"x1/2" braces from the canopy frame to the shirts above the ribs.

Anyway don't expect to walk out to your hangar or garage and knock this job out in a day or two. It requires precision and precision takes time and you have to think about what you want to do and how it is coming along as you work. But for 7 years now my canopy does not leak - at all - and there are no canopy to fuselage abrasions or wear marks.

Good luck with however you decide to work the problem.

Bob Axsom
 
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G"day Bob
Any chance of a picture of this arrangement. I am fitting my canopy now and was wondering about sealing?
 
Phil,
I didn't really understand from your post exactly what problem you're dealing with. Is it a draft coming into the cockpit, the appearance or the air noise from the gap? If it's a draft, then I may have an idea for you.

I struggled with drafts for quite a while. First I had air hitting the back of my neck from the slider bar. When I sealed that better, I had it coming in around the stick (bad area to get cold!). Then it was the flap pushrods. Then it was the rear bulkhead. They were driving me nuts (and for me that's a short trip!).

One day it dawned on me that maybe the problem wasn't the gaps; after all the cockpit isn't/can't be air tight. Air only comes in if the pressure inside is less than the pressure outside. Maybe the problem was that I was somehow generating a partial vacuum in the cockpit. The obvious opportunity for that was the high-speed air across the canopy-windshield cuff.

Sure enough I was able to slide paper between the canopy and windshield when the canopy was closed. It took me 5 minutes and some sticky weather stripping tape to get a better seal. Eureka! My problem was solved. Even tho there are gaps, the drafts gone. And I didn't have to repaint anything!
 
Thanks Guys.

Kyle, your trick would probably work, but i would probably find it less embarrassing to tell a passenger to wear a jacket than to have him stuff a piece of foam insulation down there after closing the canopy.

Bob - your solution would have been perfect if I'd done it before finishing and painting the plane, when it was still in the shop. At this point I'm not sure I have the patience to spend trying to do it without risking damaging the paint job.

Riffelj (no signature?), it is indeed the draft. I did try stick weather stripping, but as I wrote in my original post the problem is that this just gets pulled away or jammed as I open and close the canopy, precisely because of the lack of parallel surfaces during this motion that Bob described. I'm surprised you didn't encounter this problem with weather stripping. I guess you probably used much thinner stuff than I was using... maybe I'll try that if I can find some.

Sounds like this draftiness is just a minor annoyance I will have to live with for the relatively small amount of flying I do in the very cold months.

Thanks for your thoughts on this!
 
PIN 37 said:
G"day Bob
Any chance of a picture of this arrangement. I am fitting my canopy now and was wondering about sealing?
Click to expand...

If you look up Ricka's thread "Slider Canopy Sideskirt" I posted some photos there some time ago. I also made up a Power Point file several years ago that covers my approach to sealing the canopy. I will send that to you if you, have Power Point software to display the package, want to have it and give me your e-mail address. When I get some time I will try to remember to post some photo's here as well.

Bob Axsom
 
I would like the PP as well -please

Can you send it to rawhittier at aol dot com? Thanks.

Bob Axsom said:
If you look up Ricka's thread "Slider Canopy Sideskirt" I posted some photos there some time ago. I also made up a Power Point file several years ago that covers my approach to sealing the canopy. I will send that to you if you, have Power Point software to display the package, want to have it and give me your e-mail address. When I get some time I will try to remember to post some photo's here as well.

Bob Axsom
Click to expand...
 
Wow Florida John that's very helpful

I went through those and I may have missed it but there is one more that I think is important. On the RV-6 at least there is a space from the aft upper fuselage skin and forward to the aft canopy pin receptical blocks the needs to be addressed. Van wraps the aft canopy skirt around the fuselage an inch or so at this point to close this area. So every time you close the canopy this skag on each side on the read canopy skirt comes against your painted fuselage skin. I chose to close on the inside rather than the outside and made a part for each side from 1/16"x3/4"x3/4" aluminum angle. They are riveted to the longeron and the upper aft fuselage skin. Here is a photo:

reargapclosureangle2.jpg


Note the small tab riveted to the inside if the angle at the front which goes into position inside the rear end of the canopy track extrusion.

Bob Axsom
 
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Phil,
Sorry if I wasn't clear.

I am suggesting that you look to see if there is a gap in the fiberglass CUFF between the windshield and the LEADING edge of the canopy (where the slider comes forward to meet the windshield)... NOT the lower edge of the slider. It's the tubes that run from the left fuselage side, up to the canopy handle, and then down to the right fuselage side and the canopy plexi meets the windshield plexi. That's where you may be getting high speed air from the windshield, over your head, across the canopy and then aft. Because that curve acts like an airfoil, if you have a gap it'll cause a low-pressure inside the cockpit and draw air into the cockpit where ever it can. If you seal that up you won't have drafts even though you've got gaps in other areas (canopy sides, flap rod slots, aft bulkheads, etc.).

I put weather stripping on the windshield side so that the canopy will jam into it when it's closed to form a tight seal. There is no side-to-side (tearing) force when you do that.

"Jerry"
 
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