I assembled the Wd-644/C-658 roller assemblies (see DWG 41, Detail A) and inserted them into the tubes of the Wd640 Canopy Frame. Light clamping pressure with a small C-clamp held them in — I did not need to drill them to the frame until all canopy fitting adjustment had been made.
I cut the C-657 Canopy Tracks to length as shown on DWG 41.
DWG 41
I laid-out and pre-drilled the screw holes using a #40 bit using DWG 42, Sliding Canopy Top View for screw hole spacing. I then clamped the C-657 canopy tracks onto the F-721B Aft Canopy Decks.
DWG 42
I drilled the hole through C-661 per DWG 43, C-661 Detail View and then positioned the C-661 rear slider block under the receptacle on the rear center of the canopy frame weldment.
DWG 43
I drilled through C-661 and the canopy frame and inserted the bolt as shown in DWG 43, Detail J. Then I removed C-661 and de-burred the holes.
I removed the roll bar and drilled the holes up to final size in both the roll bar and in the aft canopy decks. The holes were #12 for the forward holes, ¼” for the aft holes. I used a unibit for the F-721B holes to keep the holes from wandering and then deburred all the holes.
I installed bolts/nuts/washers to hold the roll bar in place for further fitting. When the nuts had been tightened, I double-checked that the roll bar was square to the fuselage longerons. See DWG 42, View C-C. I used shims as required particularly on the right side.
I laid out and drilled #40 pilot holes for the 3/16” and ¼” bolts through the F-721B Aft Canopy Decks as shown on DWG 42, Detail A. I then drilled the aft pilot hole through both the upper surface of F-721B and the lower flange of F-721B.
DWG 42
The C-668 spacers were needed to provide a flat surface for the nuts and bolts that attach the roll bar to the longerons. See DWG 42, Section D-D.
DWG 42
I modified the C-668 spacers provided in the kit as shown on DWG 42, C-668 Detail Views.
DWG 42
When done, I had a forward left, forward right, aft left, and aft right spacer. The centerlines were marked on the upper surface of each spacer. I held the spacers, one at a time, in place against the bottom surface of F-721B and nested them tightly against the inboard edge of the longeron with the fastener centerline mark visible through the #40 pilot holes I drilled earlier. I drilled #40 through the pilot holes just enough (about 3/32” deep) to make a good center point for finish drilling the holes through the spacers off of the fuselage. I then removed the spacers and used a drill press to drill the #40 holes all the way through the spacers. Then I finish-drilled the holes to final size. I was careful to put the correct size hole in the correct spacer! #12 for the forward two spacers, ¼” for the aft two spacers.
I placed the Wd-641 Roll Bar on the fuselage in the position shown on DWG 42, View C-C.
DWG 42
The roll bar needed to have a 7/32” gap between the fuselage sides and the outer edges of the bar. If the gap had been within 1/16” of desired, I could have pushed or pulled it into position, otherwise I would have had to bend it slightly to make it fit within 1/16”. It could be adjusted quite easily by hooking one end behind something and pulling (to make it wider) or by putting one end on the floor and leaning on the other (to make it narrower). I went very slowly, as it was easy to do too much.
Once I had the width close, I clamped the roll bar in the proper position of the fuselage (vise grips worked well) and using a #40 bit, I back-drilled the 4 bolt holes up from the bottom using the pre-drilled pilot holes in F-721B as guides. The aft two holes were back-drilled using the holes in the F-721B flanges as well as the holes through the upper surfaces.
After the empennage, the sliding canopy probably raises more questions than any other installation. Fitting a structure of welded steel spaghetti to a hand-built fuselage is an exercise in patience and perseverance. Given the inevitable variations between individual frames, roll-bars and fuselages, it is not possible to give dimensions that will work every time. Instead, builders are cautioned to slow down and work carefully from “first principles.” The amount of effort and time spent on preliminary positioning and alignment, adjusting both the canopy frame and the canopy skirts, makes a big difference to the quality of the final fit of the canopy.
The RV-6/6A Sliding Canopy Assembly consists of two main components; the Windscreen/roll bar assembly which is fixed to the fuselage, and the Sliding Canopy Frame/Plexiglass canopy which moves fore and aft.
The windshield frame also serves as an overturn structure or “roll bar”. It consists of a formed steel tube weldment with a flanged base which is bolted to the fuselage upper longerons and cockpit rails. The roll bar also includes a center brace which attaches to the upper forward fuselage. The windscreen is screwed to the roll bar and bonded to the top fuselage skin with an epoxy/fiberglass base molding.
The sliding canopy frame of is made of welded steel tubing and moves on nylon rollers and slide blocks. The canopy is trimmed and attached to the steel tube frame with blind rivets and machine screws. Aluminum skirts are used to fair the bottom and rear of the canopy to the fuselage.
The canopy has three contact points with the fuselage; two rollers at the lower forward corners of the canopy frame, and one slider block at the rear top of the canopy frame. The rollers move in extruded aluminum tracks and the rear slider block moves on a builder-fabricated guide track.
The sliding canopy is held closed with an over-center spring-loaded hook latch operated by an internal/external handle. This handle is also used for sliding the canopy open or closed. There are two pins at the rear base of the canopy just aft of the canopy tracks which engage nylon blocks mounted on the fuselage. The front of the sliding canopy is held down by a molded fiberglass lip on the windscreen. The pins and lip serve as passive hold-downs, so operating the sliding canopy requires just one latch and one hand.
The empennage fairing was installed according to the details found on drawing 44.
Empennage Fairing Installation
The fiberglass fairing was fitted to the empennage surfaces by filing and the application of heat. Nut plates were installed in the indicated locations.
Nut plates locations
The rubber channel seal was adapted and installed.
The elevators were fitted to the horizontal stabilizer during construction, but the lower bolt hole in the elevator horns (to which the pushrod attaches) had not been drilled yet. These holes were best drilled with the elevators mounted to the stabilizer. This hole had to be be exactly perpendicular to the horns. If it wasn’t, when the bolt installing the pushrod was tightened, one horn would be pulled forward and the other aft, mis-aligning the counterbalance arms.
I clamped the horizontal stabilizer to the bench with the hinges hanging over the edge and mounted the elevators on the stabilizer. I then aligned the elevator counterweight arms to the stabilizer tips and clamped them so they would not move. I then measured the distance between the inside faces of the elevator horns.
The horns are individually welded and seldom does one side match the other exactly. Usually the mis-match is slight. I determined which horn was aft, then removed that elevator and drilled a #30 pilot hole in the horn at the dimensions shown on DWG 27A, Side View.
DWG 27A – Side View
I made a hard wood block that fit exactly between the inside faces of the horns. The exact size of the block was unimportant, but the two outside faces had to be parallel. I used a drill press to make a #30 hole perpendicular to the faces of the block.
Then the elevator was remounted and the counterweight arm was fixed to the stabilizer. The block was clamped between the horns and the hole in the block was aligned with the hole in the one horn. Then the block was used as a guide to drill the other horn. Once pilot holes had been drilled in both horns, they were enlarged to full size. This could be done one horn at a time.
Fitting the Horizontal Stabilizer
The horizontal stabilizer was clamped to the aft fuselage. The stabilizer needed to be perpendicular to the longitudinal centerline of the fuselage. I pre-positioned the inboard edges of the skins parallel to the longerons. This was checked by running a tape measure from the outboard end of the stab to the corner of the firewall. Using similar points on both sides of the airplane and the stabilizer was adjusted until the measurements are equal.
Once the stabilizer was located, it was time to drill the holes though the HS-714 attach angle on the forward spar.
The outboard holes had to go through the fuselage longerons, the F-710C spacer and F-710B angle (see Detail B, DWG 27A). These parts were underneath the F-714 deck and invisible. I took careful measurements and located these bolts as accurately as possible. I remembered that the vertical leg of the longeron is 1/8″ thick and the bolt had to center in the available 5/8” of the horizontal leg.
DWG 27A – Detail B
When the HS-714 angle had been drilled, I made the F-798 shims, slipped them between the deck and the angle and used the holes as guides to drill the shims.
Alignment of Empennage
I then temporarily bolted the forward spar and shims to the fuselage. Using a 3/16″ spacer I slid it between the rear spar of the stabilizer and the aft deck. This set the spacing necessary to obtain the desired 0 degree incidence. I checked this by measuring from the deck to the tooling holes in the inboard stabilizer ribs. The measurements were be the same, fore and aft.
When the stabilizer had been located, I drilled the bolt holes though the F-711C bars and the rear spar of the stabilizer.
Leonard's RV-7A Build 