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Fuji Abound
19th Mar 2007, 21:48
Three point car type harnesses seem to be becoming the norm on new aircraft. I know they are convenient and easy to use. Perhaps the passengers even feel more at home with them.

However having recently hit my head hard on the canopy its made me realise that they dont work. Great for restraining forward momentum perhaps, but useless for stopping you going up and down.

It is definitely not what you want for aeros (and fortunately they are never seen in aerobatic aircraft) but also not what you want in an instrument platform or anything that you might fly in more "severe" conditions.

BackPacker
19th Mar 2007, 22:27
The Diamond DA-40 that I fly has a three-point harnass that passengers always take to be exactly the same as a car-style harnass, but it isn't. The lap strap is completely separate from the chest strap. They just share the same buckle. But the lap strap needs to be tensioned first and stays that way. The chest strap is on a reel. So the lap strap prevents you from going up and down, the chest strap prevents you from going forward in a crash. But indeed nothing prevents you from going sideways.

For aerobatics, I agree you need a four- or even five point harnass.

Fuji Abound
19th Mar 2007, 22:33
So the lap strap prevents you from going up and down

With respect, unless perhaps you have it done up uncomfortably tight, I can guarantee you it does not, unless the strap on the 42 is different - I am sure it is not.

denhamflyer
20th Mar 2007, 08:17
A three point harness should stop upward momentum if fast - the roller should lock and the lapstrap should hold you in. If not then I think this would be a fault or perhaps the lapstrap was too loose. It wont be as effective as a full harness but in my fast car days I actually practiced being turned upside down in a three point harness and not being a lightweight I was impressed by how easily it held me. (The point of the exercise was to release yourself without breaking your neck! - apparently very common in car accidents)
The key problem for me is that there is still a reasonable amount of play 2-3 inches so if your already near the roof you may be stuffed. Flying in the recent howling winds at one point during decent I lost the ability to acturately control since I was in being buffeted in mid air for some of it. Only lasted a short while at which point I pulled the belt tighter. (The cessna belt if essentially the same as a car - but with lumpy airbags)

Mad Girl
20th Mar 2007, 08:28
denham flyer
The key problem for me is that there is still a reasonable amount of play 2-3 inches so if your already near the roof you may be stuffed.


Cool.....so there are some advantages in being a short ar*e then?????

My bonce will not be bonked on the roof ;)

ShyTorque
20th Mar 2007, 09:18
Quote: The key problem for me is that there is still a reasonable amount of play 2-3 inches so if your already near the roof you may be stuffed.
Cool.....so there are some advantages in being a short ar*e then?????
My bonce will not be bonked on the roof

Phew! Did you re-read that before posting it? That's the best "Ooer, missus!" I've read in ages! ;)

kalleh
20th Mar 2007, 11:24
One of the reasons (beside comfort and ease of use) 3-point belt is used in cars is that you want the uppe body to be able to move sideways in case the roof is deformed. When using a 4-point your shoulders are fixed and the only thing that can move is your head - a good way to break your neck.

This should not be an issue in monocoque-style aircraft like the Cirrus where it's unlikley the roll-over-bar will deform - don't know about older aircraft though.

waldopepper42
20th Mar 2007, 17:36
"For aerobatics, I agree you need a four- or even five point harnass" (sic).
Nah mate - my aircraft's got a seven point harness.

Cos I can't find a nine point one!!!:E :E