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Slider black voodoo questions

C

Captain Avgas

Well Known Member
On the RV7A slider canopy frame Vans instructions call for an inset between the rear canopy bow and the F-7112 rear skin of 1/16". That's OK but I find that if I set up for a 1/16" inset at the top of the rear bow the inset grows to 3/16" at the bottom of the rear bow. This is determined by the 1/16" dimension required between the side canopy bow and the side of the fuselage. I've attached a photo to show what I mean. In the photo, which is looking down at the intersection of the rear and side bow, I've clamped angles to the fuselage side skin and the F-7112 skin to show the extension path of the skins.

I'm sure others who have done the canopy will understand what I'm talking about.

My first question is.....did you too get an increase in inset along the rear bow ranging from 1/16" at the top to 3/16 at the bottom.

And the second question is: Vans calls for 1/16" inset for the rear bow but did anybody use a larger inset to get a tighter fit of the rear canopy skirt.

Bob B RV7A (guess what stage I'm at)

 
Rear canopy bow acceptible?

Like Av Gas, I have a problem with the rear canopy bow. He apparently never got an answer to his question and I don't know what he finally did and how it turned out so I will try again. I have a 1/16 clearance between the canopy bow at the top of the turtle deck, the bow being low as on the plans. Then I have a 1/16" inset of both sides of the side bow when compared to the canopy deck, also as per the plans. However, like Av Gas had, I have a little less than a 1/4" gap on the right side of the bow from about 9:30 to 11 o'clock so that it rests below the turtle deck skin. The left side conforms to the turtle deck OK.
Can I accept this low side on the right?
 
Have you mounted and drilled your nylon blocks yet? That will pull both sides even. I also used .032 SO for the rear skirts and with a body hammer and a dolly I have my skorts fitting perfectly with no gaps all the way around. I have more time in the canopy than any other assembly on the airplane. It is a real challenge but very satisfying when it is done. Don
 
cleve_thompson said:
Like Av Gas, I have a problem with the rear canopy bow. He apparently never got an answer to his question and I don't know what he finally did and how it turned out so I will try again. I have a 1/16 clearance between the canopy bow at the top of the turtle deck, the bow being low as on the plans. Then I have a 1/16" inset of both sides of the side bow when compared to the canopy deck, also as per the plans. However, like Av Gas had, I have a little less than a 1/4" gap on the right side of the bow from about 9:30 to 11 o'clock so that it rests below the turtle deck skin. The left side conforms to the turtle deck OK.
Can I accept this low side on the right?
Click to expand...

Would you believe Cleve that I am STILL working on my canopy (5months and counting). In the end I don't believe that the Van's specified gap between the rear bow of the canopy frame and the turtledeck of 1/16" is all that relevant. What I'd be more concerned with is getting consistency of the gap whether it be more than 1/16" or less than 1/16". If you have 1/4" at 10 OClock and 1/16" at 2 OClock then you probably do not have reasonable gap consistency and I would recommend further tweaking of the rear bow. If you do not have reasonable gap consistency then it will be more difficult to get a good fit of the rear skirts. But as I said, if in getting consistency of gap you find that the gap is more or less than 1/16" I certainly wouldn't worry about it.

After looking at several other local builders' sliding canopies (and a couple of hundred more at Airventure last year) I came to the conclusion that it is virtually impossible to get a nice tight fit around the rear skirt at the fuselage using flat aluminium sheet....unless the aluminium is worked. You need to generate some double curvature in the aluminium to get a proper fit. So Yakdriver is quite right in that regard. However I went another way to him....I used a shrinker along the rear edge at strategic locations to induce the double curvature...and then I buffed the shrink marks out with a belt sander with a Scotchbrite belt. Perfect fit. Hope this helps.

In the end I gave up completely on Van's instructions for the canopy. I didn't even think their suggested construction sequence made any sense. I just decided to fudge my way through... making it up as I went along on a day by day basis. Maybe that's why it's taken me over 5 months !!!
 
Fibreglass...

Hi Bob,
As I told Cleve a few days ago, none of these measurements are that critical. As far as the skirts go, I've seen many of them made out of fiberglass, so 1/16" here or a 1/4" there doesn't matter. The gap between the rear bow and the fuselage is bridged with something like duct tape by strips fore and aft from the bow to the turtledeck, overlapping a little as a support for the 'glass to be laid on....three layers. Later the glass is removed, the rear ends trimmed nicely and drilled to fit the rear bow....one way around all these pesky dimensional problems.

Regards,
Pierre
 
I was going to do mine in glass but a friend that has an award winning 6 told me I was cheating so I arose to the challenge and made them in metal. As with anything I think I could do a canopy now in about a week and get it to fit absolutely perfect. I keep saying the next RV I build will be a lot better than this one. I guess that is why there are so many multiple builders. Don
 
Slider canopy VooDoo

Hello,

The canopy was a chore. 112 hours of fun, I am glad that I am past that part. I tried the metal skirts and gave up and made them out of fiberglass.

One piece sides and rear, fits tight and looks great. The fellow I had help me laid up the glass skirts in less that 2 hours.

Cheating? Maybe. But it worked and I moved on. :)

Mike Ice
RV-9, firewall forward
Anchorage, Alaska
 
pierre smith said:
Hi Bob,
As far as the skirts go, I've seen many of them made out of fiberglass, so 1/16" here or a 1/4" there doesn't matter.
Click to expand...

Hi Pierre, when I was at AirVenture last year I saw quite a few sliding canopies with fibreglass skirts. But some of them didn't look all that good to me. Mostly they looked very rough from the inside. And some had developed waviness with age and I didn't like that.

It definitely takes more hand skills to get a nice fitting aluminium rear skirt. But done properly I like it better. Probably just personal preference.

In the end it probably doesn't matter which way you go....either way, the only thing that's important is learning the proper skills and taking the time to get a nice finish.

The "move-on-and-take-no-prisoners" style of building doesn't tend to lend itself to the canopy construction...it requires definite patience and finesse for a nice fit and a stress free canopy.
 
How do I bend that pesky rear bow?

Thank you for all the good advice. I, however, still need to bend the pesky rear bow about an 1/8 to 1/4 inch on the right but no matter how hard I try, all I am able to do is bend it enough for it to spring right back.

How did you bend your back bow?
 
cleve_thompson said:
Thank you for all the good advice. I, however, still need to bend the pesky rear bow about an 1/8 to 1/4 inch on the right but no matter how hard I try, all I am able to do is bend it enough for it to spring right back.

How did you bend your back bow?
Click to expand...

Cleve, this raises an interesting question. If you don't know how to bend your rear bow (which is only 1/2" and very easy to bend) then how did you bend the side bows, or the front bow. If your canopy frame was anything like mine then they would all need tweaking. On my initial canopy as supplied by Vans the central top bow didn't remotely align with the windscreen brace (which in the end it HAS to). In other words the front curved bow was grossly lopsided.

I also had further problems beyond the spaghetti mess of the canopy frame in that my canopy bubble was assymetrically blown. This caused me nightmares. I haven't heard anybody else mention this but I'd be confident I'm not the only one with an assymetrically blown canopy...it's probably common. Most builders probably just can't pick up the error because it's hard to measure it. They probably just wonder why they're having so much difficulty getting everything to come together.

Incidentally, one way to bend the rear bow is around the spare tire on your car. Do it slowly...and keep checking for movement...the bows tend to give suddenly at a certain point of flex.
 
Thanks Jim

Thank you, Jim and Kevin! I am on way now to the hangar and will give that method a try. I believe that even I can get it to work.
BTW, Bob, I was lucky in that my forward bow and side bows are fairly close to what I need, I think. So if I can get it bent some more and if I don't mess up the others in the process, I think that I can move on to the BIG CUT.
 
Hey Cheating isn't so bad if you get results like that!!!

Hey Pete,
The way you did your rear deck is great! I certainly hope that mine will come out as well. I guess that I am not opposed to CHEAT a little. ;)
 
fiberglass aft skirts

Nice little write up Pete. Wish I had done mine that way - Im sure I would have gotten a better fit.

One comment on the fiberglass method: Looks like you made your aft skirts, then attached them with Sikaflex. Seems like one could easily enough permanantly attach the skirt by applying the packaging tape release only onto the turtle deck and not on the aft edge of the canopy. The fiberglass would simply overlap onto the aft edge of the canopy and permanantly bond to it (assumes appropriate pre-scuffing). Sound ok?

erich weaver
 
Erich -Yes

Hi Erich,

The only thing that might be tough doing it that way would be trimming to size. If I did it again, I'd try to make it work as you said. You could use the same FG to canopy techniques as with the slider wind screen.
 
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