4 Point Harness in an Avid

[C5Engineer 1170]

I want to look into converting over to a 4 point set up after hearing about some of your stories. Anybody have pictures or info on attachment points for the second shoulder harness?

[Mendlerr 4]

Not sure if my kitfox could help or not but I may be able to snap a pic in a couple days. I believe some tabs are simply welded to the fuselage behind the seats

[C5Engineer 1170]

Not sure if my kitfox could help or not but I may be able to snap a pic in a couple days. I believe some tabs are simply welded to the fuselage behind the seats

Mine is not going to have those Tabs. Trying to remember if there's a bolt back behind the seat anywhere where you could use a Y harness set up like this.Would having them come up and over the bar that the seat back goes over make them too low?

 

[C5Engineer 1170]

Another thought I was having was something like the Cobeau bolt in set up bolting the shoulder straps in on the same bolts as the lap belt...Thoughts? Sorry I'm trying to do this with pictures on my laptop again while my plane is a million miles away. The answer would be pretty easy I think if I could run out to my hangar for a minute...too bad it's 8800 miles away!

 

I don't think going straight back down with the shoulder straps is the right way to do it after doing some reading on the race car sites.

 

[Mendlerr 4]

Looks similar to mine.  I have multiple sets of harnesses here at the house, some are new.  Let me take a look and see what I got.  2" belts are greatly preferred over 3 inch and you typically want the pull-down style shoulder harnesses and I prefer camlocks.

 

In my experience with harnesses I weld 3/8 plates with eye hooks into the truck of the car, over the structural frame substitute on unibodies.  I mount the harness all the way in the back at a specific angle around 10%-12% like pictured.

 

Obviously we cannot do this in a plane though.  The reason for mounting the harnesses in this fashion is so they stretch the proper amount on impact.  If you simply wrap a harness around a bar to take up the excess harness you will have a fun time in the hospital with broken collarbones or a severely hurt neck!

Edited 30 Jul 2013 by RMendler

[EDMO 1078]

I don't think I have a photo of my "Foxy" that shows the original tabs like Kitfox uses, but there are tabs on the lower tubes behind the seats for 4 belt ends to attach - there are tabs on each side back where the window tubes are, for the outside shoulder belts, and one center tab at rear of turtledeck, or a tube just forward of that, for attaching both inside shoulder belts. If you cant understand my jibber, I will try to take some photos of them.

NOTE: AC43-13 (I believe) gives acceptable "for your safety" degrees of mounting shoulder belts - Not too high, and definitely not too low - shoulder belts attached to the floor would be unsafe in their opinion. Something like 5 to 30 degrees UP from the shoulder is what I remember to keep from breaking your collar bone, or your whatever? Check it out.

If not in AC43-13, then I have it in another book. I will check on it.

EDMO

Edited 31 Jul 2013 by Ed In Missouri

[Mendlerr 4]

I was unclear, in the cars we had a harness bar behind the seats, the belts would ride along the setback brace which actually put the harness at the proper angle across your shoulder, then they turned down and ran all the way to the trunk. This allowed us to utilize the full length of the harness while still keeping it on your body and seat properly.

[EDMO 1078]

The FAA even allows the use of steel cables to extend your seat and shoulder belts to reach the mount - Of course, inertia reels are the most comfortable - if you trust them - I don't...

EDMO

[Mendlerr 4]

We used to have inertia reels in the helicopters I flew, I hated them. I greatly prefer my kitfox setup

[EDMO 1078]

I don't think I have a photo of my "Foxy" that shows the original tabs like Kitfox uses, but there are tabs on the lower tubes behind the seats for 4 belt ends to attach - there are tabs on each side back where the window tubes are, for the outside shoulder belts, and one center tab at rear of turtledeck, or a tube just forward of that, for attaching both inside shoulder belts. If you cant understand my jibber, I will try to take some photos of them.

NOTE: AC43-13 (I believe) gives acceptable "for your safety" degrees of mounting shoulder belts - Not too high, and definitely not too low - shoulder belts attached to the floor would be unsafe in their opinion. Something like 5 to 30 degrees UP from the shoulder is what I remember to keep from breaking your collar bone, or your whatever? Check it out.

If not in AC43-13, then I have it in another book. I will check on it.

EDMO

WELL, I will correct myself - I didn't find this in AC43-13, so it must be in one of my design books, or possible in Tony Bingalis' SPORTPLANE BUILDER Book? I know I have read this somewhere.

ED