Fuselage

Today I drove down to Vans to pick up a few important items that I need before going any further. Let me explain. First, I became aware that I need to make a decision about seatbelts while I'm working on this part of the center fuselage. Van's has two options regarding seatbelt systems. They offer a 4-point system that includes the lap belts you would expect, and two shoulder belts that come down over your front. Then, there's a 5-point system that includes all of that plus a crotch strap that comes up out of the seat between your legs and attaches to the lap belt. I hadn't thought about the details of seatbelts before now, and I was undecided as to which option to use. I've never given this any thought, and I don't know which way to go. The 4-point system costs less, obviously, and is easier to install. Basically, I'm done already. If I go with the 5-point system, however, I have to install brackets for the crotch straps in between the seat ribs. Now would be the optimum time to do that, while I'm working on this section of the fuselage with all the seat ribs. I wanted to check with some other builders and pilots to see what other guys are doing and make sure I'm not overlooking something important. This is a decision I don't want to take lightly.

So I wrote an email to my technical advisor, Randy Lervold, and asked him what he did and his opinion. I also posted my question on a couple of online forums. I was surprised at the fast responses from Randy and at least 15 other people on the forums. The overwhelming number of opinions were strongly in favor of the 5-point system with a crotch strap. Apparently, if you have a crash landing, God forbid, there's a chance of "submarining" where you slide under the belt and impact against the instrument panel or the canopy. Not a good scenario. But the main thing that convinced me is that several people pointed out that the crotch belt serves a very important daily function of holding the lap belt down around your pelvis, so it doesn't ride up onto your belly. Not only would that feel funny, but if you hit some turbulence or bumps, you can easily hit your head on the canopy if you aren't held down in the seat. Being held down in the seat is a very good idea. And again, in the event of a crash landing, the lap belt should be down as low as possible where your pelvic bones are. This is a much stronger part of your body and you won't suffer injuries to your soft internal organs from the belt riding up on your belly. I know this is a morbid subject. The guys also commented on how the 5-point system was just more comfortable and felt more secure. Finally, I found out that all fuselage kits now being shipped from Vans have a crotch strap kit included as a standard part of the kit. Mine didn't come with one, and I didn't order it with the fuse kit. So I had to pick one up. Now is the time to install it, before the seat ribs are riveted in place. It can be added later, but you would have to use pop rivets and it's much easier now. So once all the facts were considered, this was a no-brainer.

Here's the crotch strap kit that I picked up at Vans, with the drawing, instructions, and hardware bag. There's a pair of these brackets for each seat. (The long bolts in the upper left corner of the picture are not part of this) You'll see how it goes together very soon.

Since I was driving down to Vans, I considered another option that I didn't order with my fuse kit. These are the steps for the airplane. There's a right one and a left one and they attach to the fuselage right behind the wings. For any of the nosewheel RV's that sit level on the ground, it's a huge step up to the wing. You really can't step up there without a step of some kind, and this option makes the most sense. These weldments really impress me. They're very well made. And they are aerodynamically made with airfoil-shaped tubing, as you can see above. So the aerodynamic penalty for having these stuck out into the airstream is probably very small, or neglible. All I have to do is clean them up a bit and paint them before installing them.

The reason this is an issue right now is because if I'm going to install steps, I have to drill a hole in one of the baggage ribs for the tube to pass through and fasten to a block on the next rib, to hold the end of the tubing in place. I also have to cut "scallops" or shallow curves in the flanges of the F-623 corner ribs, to allow room for the tubing to pass through that area. I'm working on this area with the baggage ribs right now. I already cut holes in two of them for the tubing to pass through. Next I needed to cut the scallops on the F-623 corner ribs. I needed these steps so I could fit them in place and see exactly where these scallops need to be cut, and how deep. Also, as I noted a few days ago, there is a discrepancy between the construction manual and one of the drawings as far as how large to make the hole for each step. If I have them in hand, these questions can all be easily answered and my work can continue.

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