Roll Bar

There are two types of canopy available for the RV-7: tip-up canopy and sliding canopy, I went with the slider because I used to fly a Grumman Tiger and liked the easy operation of the canopy during taxi and getting in and out of the craft. The slider features a fixed front windscreen supported by a heavy roll bar and brace. The downside is that there is just no way to get to the wiring between the panel and the firewall other than crawling under the forward cabin. My aim is to try to make as much of the wiring looms as possible available just behind the panels, which, for my Affordable Panels XL design, are easily removable in three separate pieces.

This page outlines my experiences installing and trimming the Roll Bar an its support brace.

The rollbar is a curved, quite heavy duty piece of steel which has a square bracket welded on each end (see further below). It is all powder-coated and quite sturdy. Each bracket has a flat surface which sits on the fuselage deck sheet. This sheet is not strong enough to support the potential loads on the roll bar. The roll bar forces are actually born by four slotted spacers which are milled so that they very neatly fit up against the rounded edge of the top longeron where it sits under the fuse deck (image 1). I stuffed my spacers up in my first attempts (trimmed the thin segment instead of the thick segment - dummy!). LESSON - ignore the dimensions for trimming these spacers in teh drawings. Use first principles. Lay the spaces on top of the deck with their round milled edges over the position of the longeron edges. Measure how much to be trimmed from the overlap withe the rounded fuse deck edge. Be cautions and conservative.

Image 1 shows SIX spacers. You only need four, but I got more given I was paying hefty freight from Vans to receive them. These have a thin segment and a thick segment (image 2). In final position, the thin segment lies OVER the profile of the upper longeron on each side. Image 3 shows the final position, but above, rather than under, the fuse deck. These spacers have to be trimmed and rounded to fit the curve in the deck skin as it forms a right angle (image 4). Two #30 pilot holes are drilled in exact position (called out in DWGs - be careful) through the deck where the AN3 front and AN4 rear support bolts will go. When you manage to get the spacer in position UNDER the deck (image 5), you can see their centrelines through the pilot holes and you can mark the hole position. Then you remove spacer and use a good drill press to drill the 3/16" and 1/4" holes in the front and rear spacers, respectively. I drilled these spacers in pairs, using one to support the other (image 6) so that the drill met the surface at a secure right angle (when clamped).. I then placed the roll bar over the fuse deck and found it was about 3/16" too wide!, There needs to be exactly 7/32" clearance between the roll bar bracket edge and the fuse edge. Image 8 shows that this was originally too little clearance

milled spacers

fit the longeron

like so..

in about this posn

but under the deck

drilling with a press

all done

roll bar bracket

 

Image 1 below shows how I attempted to reduce the width of the roll bar. It certainly helped, but in the end I had to apply a little pressure to the bar to get everything lined up. Image 2 shows how, fortunately, I did not need to use any shims to get my roll bar square. Thank you, quickbuilders in the Phillipines!! Image 3 shows the roll bar in FINAL position with EXACTLY 7/32" between the edge of the flange and the fuse edge, on the left side. The right side was not so good (6/32"), but Support@vans said that it would be OK. The next two pictures are with the front skin clecoed in place. You can see that the edges of the skin and the roll bar line up pretty much. Image 6 shows the roll bar bolted in final position, without the central brace. The central brace is a piece of powder-coated steel tube which bolts (1/4") to the centre of the roll bar up top, and which bolts (3/16" x 2) to the reinforcement angle of the front superstructure below. Images 7 and 8 show the dwg and actual components of this lower attachment.

bending it IN

90 deg exactly

7/32" exactly

lines up w front skin

on both sides

in place

brace attach dwg

brace attach actual

In its initial form, the brace is purposely made too long (Image 1). I slid it into the centre of the slot in the front superstructure and skin, and then aligned it with the rop bracket. It was about 3/4" too long (image 1). So I trimmed the top part of the brace (image 2), and re-fitted it to the front superstructure reinforcement angle (image 3). I then carefully drilled the top roll bar bracket and the brace tube for the 1/4" bolt. This is actually quite difficult. I used a 3/16" angle drill to get started (this could be aligned straight to the tube), and then disassembled everything for final drilling (image 4). In the end it all looked square, true and strong. On to the sliding canopy..

too long..

trimming

where to drill

all done