BSwayze

BSwayze

Well Known Member
I'm at a point in the center section of my fuselage where I need to make a decision about seatbelts. I notice that Vans sells 4-point seatbelt and harness kits, or 5-point kits with a crotch strap. Now would be the time to install the brackets if I go with a crotch strap. So I'm wondering...

What are most builders using? I admit I haven't paid much attention to this matter until now. What are the advantages/disadvantages of each kind other than the cost? Is it a compromise in safety to go with a 4-point seatbelt?

Thanks for any comments, suggestions, or input
 
I think the main difference is the 5 (or now, 6) point harnesses prevent "submarining" in an impact. Eg, you can't slide down under the lap belt.
 
Better in turbulence

The 5 point is much better when it gets bumpy. Helps keep you in the seat better with less chance of hitting your head on the canopy.

Cheers

Peter

PS You can retro-fit these later but it's much easier when building the centre section.
 
re: go 5 point

My brother did a 4 point in his 9A. The problem I have, is the shoulder harnesses pull the lap belt up into your gut. For that reason, I'm putting the 5 point in my -10, front & rear seats.

Marshall Alexander
RV10 N781DM
fuse/panel/cabin top
 
I like the crotch strap as it keeps the lap belt down across your thighs where it is supposed to be and doesn't let the shoulder harness pull it up. Mandatory for any negative G acro. Don
 
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Safety and comfort

I'm not convinced of the merits of the crotch strap preventing "submarining". I don't think this is a likely scenario. This is more likely in a car where you can get hit from behind.

However, I do agree with Marshall, the crotch strap does keep the lap belt low on the hips where it belongs. The lap belt should be installed so that it holds you down into the seat. The crotch strap helps this be preventing the shoulder straps from pulling the lap belt up. The shoulder straps should prevent forward movement (into the instrument panel), not to hold you (via the shoulders) into the seat when in turbulence or inverted! Without the crotch strap, we will find the shoulder straps will exert downward pressure on your shoulders in these situations. This can cause broken collar bones.

In the corporate jets I fly, one does not have a crotch strap and it drives me nuts. The lap belt is always riding up towards my stomach where it will do no good (maybe some harm?). Fortunatly, that airplane will soon be replaced and the new aircraft will have a five point system.

Go with the 5 point, it is more comfortable, safer and will give you the feeling of strapping in, becoming one with your machine, not just getting in it!

Scott A. Jordan
N733JJ
 
In the UH 60 I fly there is a five point harness. In the C-12 (Army King Air) there is the standard 4 point. The 5 point harness is much more comfortable because the lap belt doesn't have to be as tight to stay in position. In the event of a negative G loading the lap belts posiion is maintained by the crotch strap not your hips. My -8 will have the five point harness.
On the subject of restraints, do any of you guys use an inertia real on your harness? Pros? Cons?
 
Do it!

If you have the option of installing the crotch strap, do it.
The best thing it does is to keep the lap belt low where it belongs.
 
Never Armour All critical surfaces.

I have a four point belt systems and would prefer five because of the turbulence we get in the Rockies.

Install the hardware needed for a five point.
 
If you ever have a ground accident, the crotch strap will help keep the lap belt down over the pelvis. The pelvis is very strong, and can take the loads from a substantial deceleration without causing signficant bodily injury. Without a crotch strap, the lap belt will ride up above the pelvis, and the loads are taken by the internal organs. The internal organ may receive significant damage that would have been prevented if the lap belt had stayed in place over the pelvis.

Install the crotch belt. The life you save may be your own.
 
Crotch Strap Adjustment

The only problem I have with Van's crotch strap is that the entire seat bottom (and likely the seat wedge) have to be removed so the belt length can be adjusted. Then the passenger has to sit down and test-buckle up. It would be so much more convenient if the passenger could adjust the belt length while sitting.
Leland
RV9A
 
N733JJ said:
I'm not convinced of the merits of the crotch strap preventing "submarining". I don't think this is a likely scenario. This is more likely in a car where you can get hit from behind....
Click to expand...
FYI - The crotch strap will do nothing for you in a car, if hit from behind as all the force pushes you into the back of the seat. In fact, the seatbelt does very little on the initial impact when hit from behind, secondary impacts are another story.

This topic has been discussed on the forum a number of times. Here are just some of the threads a search pulled up:
http://www.vansairforce.com/community/showthread.php?t=37650
http://www.vansairforce.com/community/showthread.php?t=21922
http://www.vansairforce.com/community/showthread.php?t=15279

The idea of the crotch strap is to keep the lap belt from laying across your stomach, injuring your internal organs in the event of an accident.

Most people tighten their shoulder harness first, then the lap belts. This is wrong. In a four point setup, you tighten the lap bet as tight as you can and then tighten the shoulder harnesses. With a sub-strap, get that right, then the lap belt, and then the shoulder harness.

Sub-straps really don't have anything to do with negative G's as you won't be doing those in your -9, except when you hit those air pockets.

BTW, I have the sub-straps in my -9 and have yet to have a passenger complain. Get some camloc seatbelts, brand does not matter, and they are very easy to use, you won't need a third hand to put them on.
 
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Thanks, everyone, for all the comments and input!

I have definitely decided to put in the brackets and go with a 5-point system. The issue of the lap belt riding up on your gut is something I would have never known about or thought of had it not been for your help. Thanks again!

You can follow my progress on my web page, if you like.
 
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