BlackRV7

BlackRV7

Well Known Member
Since I am going to shoot paint on my top cowl and forward deck again this Sunday...and I totally dislike the hinge pin on the top cowl at the firewall, I am going to install skybolt fasteners this evening.

I do understand we need to scallop the fasteners strip on the firewall. Question, has anyone, or could one, simply cut 15...say two inch strips, one for each receptacle and rivet those on the firewall thereby doing away with the time consuming scalloping?

Drawbacks, bad idea, why reinvent the wheel comments welcome.
 
It goes under the top skin/firewall lip..

....Dana, as you know. So if you're gonna drill out the rivets that hold the hinge in place, yep, you can use several shorter sections.

Regards,
 
Dana, sounds good to me.

If I had it to do over again, I would not scallop the vertical sections on the sides of the firewall. There's a tendency for the rear corners of the cowl halves to slip in between the scallops if you don't manage to align things closely when you slide the cowl into place. Sooner or later I just might wind up missing some paint.

It's hard to bend .050"-.060" scallops for fit with the strip in place; the edge of the firewall flexes. Individual sections as you describe (assuming you had them clecoed in place) could be removed one at a time for adjustment. You could easily pound a little compound curve into them if required. Just lay them on a piece of soft wood (instead of a shot bag) and use a big face hammer.
 
Solid strip, no scallops

First time I did this, I did scallop in between the fasteners. What a PITA that was.

For the rebuild, used a solid strip, and fluted between fasteners to get a nice curve.

Just FYI,
 
Thanks gang, I sure was not looking forward to scalloping. I do like these skybolt, as I have them on the bottom of my cowl. The initial fitting of the cowl, while drilling the #30 holes was a piece of cake.

No more drilling a canopy, no more hinge pins!!
 
BlackRV7 said:
Since I am going to shoot paint on my top cowl and forward deck again this Sunday...and I totally dislike the hinge pin on the top cowl at the firewall, I am going to install skybolt fasteners this evening.

I do understand we need to scallop the fasteners strip on the firewall. Question, has anyone, or could one, simply cut 15...say two inch strips, one for each receptacle and rivet those on the firewall thereby doing away with the time consuming scalloping?

Drawbacks, bad idea, why reinvent the wheel comments welcome.
Click to expand...
Actually, scalloping need not be time consuming. I found it to be a quick and easy process, actually. Using a band saw, I cut out a "V" shaped area between each fastener location in an effort to remove the majority of excess material possible using the band saw's relatively straight cuts. Then, I installed a rotary file in the drill press and adjusted the drill press so the rotary file fitted to it barely penetrated the surface of the table through the hole in its middle. Sort of like using a router.

2mhugja.jpg


With the strap now laying flat on the table, I simply "walked" it around the spinning rotary file to shape and finish each scallop. I did the whole 48" long strap that way in a matter of several minutes. I had no need to flute or cut up the .050 strap either as -8 builders might have to because the -8 series has a more severe cowl curvature to it than the -6 series. -8 series builders may well have to make up several strap segments for its cowl to fit properly. In my case, the one piece .050 strap I fabricated fit just fine with no fluting required either. Additional pictures here:
http://www.vansairforce.com/community/showthread.php?p=308527#post308527
 
I agree with Rick, and did similarly with the scalloping of a single piece. IMO, having a single piece of Al makes more sense and is actually less likely to be an issue with misalignment (I've had no problems so far). Making the small bends required was not an issue.

greg
 
How did it work out?

Just reading threads about cowl fitting and 1/4 turn fasteners and read this one with interest. I'm wondering if Dana or anyone tried the individual strips for the fasteners and if so how it worked. I'm seriously giving it consideration.

Thanks
 
We took advice from Peter James in Australia and the process was quite quick.

Measure the distances between the camlocs, step drill for the radius of the scallop, straight lines to the edge, round off, bend down to fit the cowling, the end :D

Peter - can you post your photo please if you read this ?

Mike
 
Another alternative

You can do it with a single solid strip, no scalloping, no fluting, no shrinking. The secret? Recognize that the curvature up there is actually not complex, but it is conical, not cylindrical. That means that for the strip to be able to follow the curvature correctly all the way around, its aft edge that nests against the firewall will actually need to be curved, not straight.

Getting the curve right is an iterative process of progressive trimming, but not too difficult or time consuming. I got mine done in a couple of hours one evening.

Disclaimer: I haven't actually fitted my cowling yet, so I can't report the final results. But I have fitted this strip to the firewall, and it does continue the curvature of the boot cowl perfectly. And worst case, if the fit with the cowl still isn't good, then I'll cut some scallops and bend tabs as needed. There's always that fallback. But even if it comes to that, then what I have now should be a much closer starting point. FWIW.
 
Scallop to Hinge pin connection?

I've placed the aluminum strip along the top cowl area and am planning on using camloc's along the top cowl as well as the horizontal line connecting both cowls. I'm using stainless hinge piano hinges on the bottom of the lower cowl and aluminum piano hinge on the sides of the lower cowl.

I'm also going to use the fiberglass guru's (Dan H.) fiberglass strip along the horizontal line of the lower cowl.

I'm trying to figure out a way to connect the upper and lower cowl at the point where the horizontal line connects them together at the firewall.

Do I run the fiberglass strip all the way to the fire-wall and use a camloc to connect the upper cowl to the bottom there? or Do I have the scallop continue down to that point and connect the top cowl to the scallop alum? The second idea gives me the feeling there won't be a good mate at the point.

Any ideas and pictures would be appreciated.
 
We have Skybolts over the top and on the bottom - piano wire down each side.

The piano wire slides in from the back and is locked with a 3/4" 90 degree bend at the rear, tucked into a notch in the lower cowl.

Got the idea of here somewhere..........

Works really well, simple, quick to remove and install, no stress on the piano hinge ears.

A great compromise.
 
roee said:
Getting the curve right is an iterative process of progressive trimming, but not too difficult or time consuming. I got mine done in a couple of hours one evening.
Click to expand...

How about just taking the forward top skin of the fuselage and use the forward edge as a template for the strip? If you lay the top skin out flat, you can see there is a slight curve to the forward edge of the top skin. Assuming this shape matches the conical curve of the fuselage, the underlying strip for attaching the camlocs should match the same curvature.
 
That'll work

bruceh said:
How about just taking the forward top skin of the fuselage and use the forward edge as a template for the strip? If you lay the top skin out flat, you can see there is a slight curve to the forward edge of the top skin. Assuming this shape matches the conical curve of the fuselage, the underlying strip for attaching the camlocs should match the same curvature.
Click to expand...

Bruce,

Yeah, that should work fine.

Note that the nominal curve for the strip will actually be ever-so-slightly different because of the way it under-laps the skin. But the easy way you suggested will get you plenty close enough (I checked mine, and the max difference between the two is only about 1/32" at the outboard ends).

In any case, the key to getting the installed strip to match the curvature of the skin accurately (after having cut the curve as discussed above) is to make sure that it's clamped in position accurately when you match-drill the rivet holes. With the strip clamped in place, check by laying a straight edge on the skin, perpendicular to the skin edge, projecting forward over the strip, and make sure that the strip is parallel to the straight edge (i.e. there's an even gap between strip and straight edge). Do this at intervals of a few inches along the entire length of the strip. Adjust the position of the strip as needed. When it's all good, drill.

-Roee
 
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