Apr 18, 2024     Cockpit floor update - (8.0 hours)       Category: Interior Finish

Was monkeying around trying to figure out assembly sequence for the cockpit area prior to covering, so I got the cockpit floors out to see where in the sequence they would need to be installed. Turns out it's pretty early in the scheme of things.

The finish on the floors is pretty nice, so I'd hate to scuff it up too badly and planned to cover them in masking paper prior to install. Got me to thinking about heel scuff plates for the rudder pedal areas. It will be easier to install now than anytime later, so I did.

Forward ones are stainless steel and bonded in place. The rears are screwed down as there is one floor install screw that needs access underneath the rear plates.

  Nov 07, 2020     Cockpit floors - (27.0 hours)       Category: Interior Finish

Began the cockpit floors with the forward pair. Forward cockpit floor is in two pieces, a left and right split longitudinally down the middle. Made a cardboard template (didn't get a picture of it before I tossed it) of the right half first, then after using it to fab the right floorboard, flipped it over to produce the left floorboard. Two identical 3/16" thick acft plywood blanks were used. Seems kinda thin for floorboards, although this stuff is pretty stiff and they are criss-crossed with all kinds of support from below, the two panels would flex past one another along the centerline. Scribbled outside the lines a little by bonding strips to the right panel along the centerline and installing T-nuts so the two panels will now screw together along the centerline. The third picture shows the bend in the forward floorboards. The forward floor panels also require cutouts for the rudder pedal pivots. I waited until the panels were installed before locating these cutouts from below to ensure an accurate cut and full rudder pedal travel.
Will likely install some sort of anti-chafe plates behind the rudder pedal locations near the heel brakes. TBD.
The aft floorboard is one piece and steps up one inch from the forward ones. The aft floor requires spacers bonded to the bottom to lift it off the steel framework and longer screws to attach it to the installed nutplates. Spacers for the rear floor are bonded to each of the aft ends of the forward floor panels and threaded inserts installed to accept the #8 machine screws holding the aft floor in place.

  Feb 09, 2020     Cockpit seat construction - (54.5 hours)       Category: Interior Finish

Sets appeared simple enough. Frames are 3/4" X 0.035" tubes with four bends at 4" radius. Packed tubes with pool filter sand (fine grained white stuff looks like hourglass sand) and plugged the ends. Previous bends on longerons and horiz stabs with this stuff went well but the 4" radius is tighter than the others. Attempts with bending blocks and Baliagh tubing bender dies either left dents or flat spots or wrinkles I wasn't happy with. As a last resort, went with a conduit bender... worked great but I'm surprised I didn't break it. Packed and plugged with sand this 4130 steel tube has got to require t least four times the force required to bend the same size conduit. Basically had to climb on top of the bender with all my weight balanced on it. Drew bend angle templates on the tabletop to match bend angles consistently but still difficult to get all four accurate enough to produce an accurately dimensioned frame with no twists. Ultimately cut the nose portions apart in the middle and re-welded together with an insert and rosettes to get the width dimensions correct. Then cut the full nose portions off and similarly re-welded in a seat jig when I discovered I had the fore-aft dimension incorrect and had a full-aft stick to seat nose interference issue. The nice thing about welding everything up in a seat jig is both seat frames are dimensionally accurate with no twists or tapers going forward from here.
Front seat was trimmed and fitted with legs into the fuse first, then seat mesh added and 1/8" rod across the top to tie the cut mesh ends together. Shamelessly copied another Hatz builder, Ed White, who modified his aft seat to include a tilt mechanism to access the area behind the pilot's seat. Two clevis pins will secure the top of the seat while two pivot points allow the seat to tilt when the pins are pulled. If tilted too far the seat nose will contact the elevator pushrod just aft of the torque tube. not good. Welded rectangular tube wedges to the angled pivot legs to limit the seat tilt. After welding in the seat mesh considered adding a crotch strap wrapped around the seat nose. Will require cutting a small section of the seat mesh out along the nose and reinforcing the mesh loose edge. On a related note, pictures of me in the seat shows my shoulders several inches above the fuselage top longerons and adjacent crosstube. Observed several other Hatz's where the shoulder harnesses installation lies across that crosstube. I think that position is too low for me even without sitting on a cushion. This is a safety issue as spinal compressive forces can develop from too low mounting positions if the harnesses are ever used in extremis. I believe the recommended reference is something like 5 degrees below to 20 or 30 degrees above; This being the angle formed from the anchor point to the top of the shoulders. Will undertake to engineer a higher shoulder harness support location.