Shoulder harnesses for rear seat

[Zzz]

I could have sworn there was a discussion on this here a while back, but I can't find it now.

I'm spec'ing safety restraint systems for my 4-place right now, and while not ideal, I think the overhead crossbar immediately behind the front seats will be okay for anchoring the 3-point Y-strap inertial reel style I plan to use. I don't plan to reinforce the crossbar with a compression or tension member.

For the rear seats though, there's really no good place to anchor a shoulder harness reel. It looks like one could weld a crossbar into the triangles that are formed by the top of the fuselage between stations M and L. Has anyone done this?

[Mark Goldberg]

Zane, would you be interested in helping develop a seat belt package by this company we have been working with? They developed and have delivered the first seat belt package for a Patrol. It looks very good. I think they will be a good source. The quality looked very good. They make seat belts for the certified world also. Contact me privately if interested. Mark

[Greg_Marlow]

Any progress on the seat belt source? I'm at that point...

[S Lathrop]

I designed my harness system for the 4 place and had the Hooker Harness company build the system.

For the front seat I am using a 3-point Y type shoulder harness with the reel for the shoulder harness mounted just above the cockpit ceiling. I added a diagonal tube to the 2 diagonals above the rear seat to mount the reels. I tried to align the reel and shoulder harness so that the mounting of the reel would not be torqued ( deflect ) if the harness was loaded as it would be in a crash.

The rear seats use a cross the chest shoulder harness, with the adjuster just above the shoulders. The harness is mounted to the vertical members behind the seat and the vertical member above the cargo door center.

I raised the mounting points for the lap belts from where they are shown in the plans. I felt that the angle of the belts across the lap was too low with the original design. I chose to use the standards from my work on race cars for harness mountings. I have had the unfortunate opportunity to test seat belt mountings in race cars on several occasions.

[Bcone1381]

I think it is rare that a builder community would have someone with such a high level of expertise in seat restraint.

[S Lathrop]

Here is a picture of the shoulder harness reel mounting.

[S Lathrop]

Here are some pictures of my lap belt mountings. The lap belts for the rear seat have similar brackets but the brackets are welded to the seat on the outsides and the center is a bolt on bracket to that mounts to the floor tubing structure. The mounts have a 5/16 bolt in double sheer and the brackets are free to rotate about the mounting bolt.

[Zzz]

Zane, would you be interested in helping develop a seat belt package by this company we have been working with? They developed and have delivered the first seat belt package for a Patrol. It looks very good. I think they will be a good source. The quality looked very good. They make seat belts for the certified world also. Contact me privately if interested. Mark

Mark, yes. I can help. I'll email you.

[Zzz]

I raised the mounting points for the lap belts from where they are shown in the plans. I felt that the angle of the belts across the lap was too low with the original design. I chose to use the standards from my work on race cars for harness mountings. I have had the unfortunate opportunity to test seat belt mountings in race cars on several occasions.

Thanks for the info and photos. Do you really think that there's such a thing as the lap belt being too low across the waist if there's a shoulder harness?

[S Lathrop]

Thanks for the info and photos. Do you really think that there's such a thing as the lap belt being too low across the waist if there's a shoulder harness?

Yes, but I am certainly not an expert. All the racing organizations I have experience with want the lap belt to secure you hips. When I mocked up the lap belts originally, they just secured my legs to the bottom of the seat. With the belts raised as I have them, I can have the belts tight without hindering my leg movement. Also the lower the lap belts, the more load the shoulder harness will have to carry.

The only time I have had belts any tighter than in a race car was the one time I did some spin training in an aerobatic plane. In that plane, the belts were just as they are in my race cars. That plane had a second set of belts that were tightened with a ratchet system.

I even studied installing a second pair of shoulder harness belts that came from the floor, up my back, over my shoulders and down to the lap belt. These belts would help support my upper body if the plane were inverted. That is something the current belts do not do. The over the shoulder belts would be loose enough to allow the upper body to move as necessary in the cockpit but hold you down in the seat when inverted or in severe turbulence. I gave the idea up. In a race car the shoulder belts are mounted even to slightly below you shoulders. You actually use the shoulder belts to support you upper body.

I felt that the higher belt location would be more comfortable when the belts were worn tight enough to secure you lower body adequately.