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.

Rear Fuselage Skins Done

Time: 5.5hrs

A momentous day for the airplane. Today the rear fuselage got closed up. Before closing it up I doubled checked that all the holes that need to be dimpled for the parachute area where correct. The only way to really check is to place the cover one the parachute box hole and verify that any holes that are covered by the cover skin are dimpled. I missed two on the right front side so it was good I checked.

Lots of photos below

Here’s the left and right side, checked and ready to go for riveting. The two areas I had some fitment issues where the tail cone along rib 6 (I think) and up in front on the right side along the join to the bottom skin… maybe 10 rivets. Other then that everything lined up great.

All the dimpling finished and checked for the parachute area.

Com1 antenna mount in place. I’ll need to install a few rivnuts here later for mounting the antenna.

Top of fuselage along the join. I used an edge tool to put a bit of a bend on the edge so that it seals well. Seems like it will work well. Thanks Peter for sharing this on your build log.

This is the luggage door area. The spot where the open rivet holes are have a spacer behind them. The spacer fits between the inside of the skin and a channel piece, But I noticed that the spacer they give isn’t really thick enough so I’ll have to make a thicker one or add to the existing. I found this after I riveted it and saw that he skin was being pulled a bit so I drilled out the rivets. I’ll have to come back to this.

Here’s where the space goes. It’s a good size gap, probably 1/8″ or a little less.

Here’s the spacer only about a 1/16″

Almost done

A good shot of the holes that I sized up to 4mm. There are a few on rib 6 and the last 4 holes on the top join. The long line on the top to bottom skin join is because of a prior issue with the skin and the longeron holes not lining up.

Still need to do some work here.

And it’s done. It all came out pretty good. Not too many bumps or pulls in the skin.

The only area that may need some work is the top middle section right where the com1 antenna and parachute box area is. Even though I made a spacer along the rib for the antenna bracket there is bump in the skin. It’s not that big of a deal since the parachute cover will cover that area up, but it would be nice to get it looking better. I did notice that even on the factory built planes this area is bumpy so I don’t feel too bad.

So next is to finish up riveting the luggage area… floor, parachute box, etc. then I should be good to put the front fuselage side skins on.


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.

Grommet Edging for Rear Fuselage Ribs

Time: 1.5 hrs

Things done today:

  • Drilled out a few rivers on the tail cone/rear fuselage skin area to 4mm
  • Installed edge grommet on ribs where wiring passes through

This was suggested by Jean. He said that sometimes even if the wiring is wire tied it will rub on the edges of the ribs. I went through and installed a small piece of edge grommet on all these areas… maybe 10 or so. I wish I would have thought of this before the bottom skins were on… boy what a pain to do this now.

Good to Go

Time: 2.25 hrs

Today I worked on the fitment of the top rear fuselage skins at the tail cone. Prior to priming the skins I had do a quick check to see how everything lined up. It seemed like everything was lining up well, though I hadn’t looked at all areas. Now that I’m getting ready to rivet the skins on I’m seeing there are a few areas that need some work. The tailbone section is one of them. It’s looking like I’ll need to up size a few rivets to 4mm since there is just no way to get things to line up using the existing holes.

Also Jean from Torrance TAF came by to check out the project before I start closing things up. He was very happy with what I’ve done so far and had a few suggestions. So it looks like I’ll work on implementing what he mentioned and then I’ll start to close up the rear fuselage.


Parachute Box and Cable Tray

Time: 1.0 hrs

Did a test fit of the parachute box and the cable tray. Had to drill out a few missing holes, but everything fit well. Still trying to schedule time with Jean from Torrance TAF to come up and look over the build before I start closing things up.

Just one missing from the right side parachute box.

These three holes were missing for the new cable tray.