Tightening seatbelt harnesses

N941WR · #1 12-04-2006, 06:51 AM

A post in a different thread indicated that there is a misunderstanding with regard to the proper sequence for tightening your harness.

First off let?s talk about sub-straps. These are not so much to keep you from submarining under the lap belts as to keep the lap belts in their proper place in the event of a sudden stoppage. Their main goal is to keep the lap belts down low, across the hip bones. If your lap belt can ride up across your stomach it is not properly adjusted.

In an accident, IF the belt rides up across the stomach, it CAN cause serious damage to your internal organs. You may survive the accident but you probably will die later from this damage. This is one of the main reasons why all SCCA sanctioned race cars are required to have sub-straps with two attach up points. (All this is learned from five years as an SCCA Safety Steward.)

If your airplane is not equipped with a sub strap, tighten the lap belts first, pulling them down across your hips as best you can. Then tighten the shoulder harnesses. If you tighten the shoulder harnesses first, you will lift the lap belt up across your stomach.

Just another thing for you to think about when strapping yourself in. Remember, speed does not kill but rapid deceleration can be deadly.

AlexPeterson · #2 12-04-2006, 07:22 AM

Bill,

Do you know of any crash test dummy video of 4 vs 5 pt. harnesses? I would suspect that might convert those holdouts flying 4 pointers.

Thanks.

LettersFromFlyoverCountry · #3 12-04-2006, 08:27 AM

I realize much of the attention from this latest crash is focusing on seat belts, but i would think the quality of the seat itself is quite important.

fl-mike · #4 12-04-2006, 11:07 AM

Quote:

Originally Posted by N941WR

In an accident, IF the belt rides up across the stomach, it CAN cause serious damage to your internal organs. You may survive the accident but you probably will die later from this damage. This is one of the main reasons why all SCCA sanctioned race cars are required to have sub-straps with two attach up points. (All this is learned from five years as an SCCA Safety Steward.)

Schroth has a good write-up on proper belt routing etc. on their website. They recommend AGAINST 3" lap belts for the same reason you stated, it puts the loads too high on your belly. The section on shoulder harness mounting and strap angles is interesting too. Might explain why some folks end up in the baggage compartment (6/7) following an accident.

N941WR · #5 12-04-2006, 12:24 PM

Quote:

Originally Posted by fl-mike

Schroth has a good write-up on proper belt routing etc. on their website. They recommend AGAINST 3" lap belts for the same reason you stated, it puts the loads too high on your belly. The section on shoulder harness mounting and strap angles is interesting too. Might explain why some folks end up in the baggage compartment (6/7) following an accident.

Could you find the link and post it?

Thanks, it sounds like good reading.

fl-mike · #6 12-04-2006, 01:09 PM

http://www.schrothracing.com/docs/Co...structions.pdf

http://www.schrothracing.com/tech/10

Jconard · #7 12-04-2006, 02:33 PM

The mounting points in an RV are not well optimized and the 5th strap simply keeps you from submarining...which the high spar does a good job of anyway. The sub strap mounting is a joke in terms of both strength and positioning.

These harnesses, when installed in a race car, are installed specific to the car, the cage, the driver, and the seat. We do not even approach those ideal mounting locations.

The problem with the shoulder harnesses in the RV6&7 is that there is no guide/support where they cross your shoulders. All race cars limit the width of spread between the belts, which we do not. Look at the shackles on a decathlon, which grab the belts and make them approach the pilots shoulders at just the right angle to the shoulders for both correct restraint.

If you really wanted to improve the shoulder harness design, you would mount some sort of a guide bar on the bulkhead immediately behind the seats which would limit the width spread of the harness and create a slight wrap over the shoulders.

The sub strap should fasten under the floor back where the lap belt fasteners fasten and loop through another guide immediately under the seat to come up to the latch. If you ever look at a formula car installation, the sub belts are typically moutned this way.

captainron · #8 12-04-2006, 04:33 PM

[quote=Jconard]The mounting points in an RV are not well optimized and the 5th strap simply keeps you from submarining...which the high spar does a good job of anyway. The sub strap mounting is a joke in terms of both strength and positioning.

Anyone have a pic of Van's 5th attach hardware, or a pic of a better enginered 5th point mounting?

Jconard · #9 12-04-2006, 09:43 PM

Go to sparco or schroth and read through all the installation data. Neither the sub strap, nor shoulder harness cable would pass tech in any sanctioning body.

tangocharlie · #10 11-05-2007, 05:38 AM

[quote=captainron;88999]

Quote:

Originally Posted by Jconard

The mounting points in an RV are not well optimized and the 5th strap simply keeps you from submarining...which the high spar does a good job of anyway. The sub strap mounting is a joke in terms of both strength and positioning.

Anyone have a pic of Van's 5th attach hardware, or a pic of a better enginered 5th point mounting?

I know this is an older thread, but am looking for a picture of this as well...

Thanks in advance,

Tammy