Firewall Soundproofing

Time: 2 hrs

Things done today:

  • Installed soundproofing on interior side of firewall
  • Working on trying to fix lumps in rear fuselage skin near parachute box opening
  • Made extra spacer for luggage door area

I didn’t have much luck with fixing the little bit of lumpiness on the top of the rear fuselage near the parachute box. I drilled out a few of the rivets and trying to rework the area. It’s minimally better, but not much of an improvement. The good news is that once the skin that covers the hole for the parachute goes on you’ll never see it. So while I know it’s there at least cosmetically it will look OK.

A suggestion from Jean (Torrance TAF) was to install soundproofing on the interior side of the firewall. He had mentioned that he did this on the prototype and was very happy with the way it reduced the amount of engine noise in the cockpit. He wasn’t really concerned about heat he said that the firewall really doesn’t get very hot.

The job went much easier then expected since I had already installed a few items on the firewall I thought it would be much more difficult. I did one full sheet of material on the top part above the bracing and then I separated the bottom section into to pieces. On the bottom section I started by sticking the long edge of the material under the brace and then worked my way down by peeling the backing off the material. I used new, sharp exact blade to cut around the heater box and the console sides. The grommet holes were made form the other side of the firewall with a long razor blade. They came out OK, not as perfectly round as I’d like, but still not too bad.


I made an extra spacer for the short section on the right side of the luggage door. The spacer installs between the skin and a channel piece that fits above the luggage door. I had noticed that the skin was getting pulled in a bit too much on those two rivets that hold in this section. The gap between the skin and the channel piece is about 1/8″ and the spacer provided is only about 1/16″. I had some scrap material that got me pretty close to 1/8″.

Luggage Area Done

Time: 3hrs

Things done this morning:

  • Riveted luggage floor bracing
  • Riveted parachute box to bulkhead and luggage floor
  • Riveted parachute box to top skins

There were a few rivets on the underside of the luggage floor that hold in the bracing that I left to rivet until later. I was a little concerned that It would be difficult to rivet, but it wasn’t too much of an event.

Now off to the beach for some time with friends.

This areas is going to need some work. It gets covered by the parachute skin cover, but I’d like it to be a bit less bumpy. I think if I bend up some of the rib flanges it might help. I need to get a few more countersink 3.2mm rivets though.

All riveted. Almost ready to put on the front fuselage side skins, but I’m thinking of sound proofing the inside of the firewall first. I was thinking of doing this and Jean (from Torrance TAF) had mentioned that it really helps cut down on engine noise so I’m thinking it may be something worth doing.

Getting Ready to Close It Up

Time: 2.75 hrs

Things done today:

  • Finished putting edge grommet of rear fuselage ribs
  • Greased long elevator push rod at bushing in rear fuselage
  • Riveted hard to reach areas on luggage area and parachute box
  • Clecoed rear top fuselage skins
  • Drilled a few missing holes in skins for parachute box

Gnarly grease for the long elevator rod. You can put this after through the access door, but it’s much easier when the skin is off.

I decided I should rivet the above areas in the luggage area now since it’s going to be difficult to do later when the top skin is on.