Seatbelt Attach Hardpoints

[Cozy1200]

Last night I epoxied the plywood seatbelt attach points into the shoulder support. I've since discovered that Nat updated this to the 8.5" separation from about 10". One of the concerns from reading the archive is that the narrower measurement may cause the seat belts to rub your neck. For those using the newer dimension, I'd appreciate your feedback.

[Steve Innova]

Some people have thicker necks, and wider shoulders.

 

If you're one of them, consider making the pilot seat to your comfort level, but keeping the passenger seats at 8.5".

 

There are documents online that describe ideal aircraft harness separation levels.

 

Or you could make your decision based on the FAR requirements, that's what I've done.

[Edge 513]

If the 8.6 inch wide bolt location chafes you, you can also use the 2 inch wide belts which are sometimes listed as JR racing belts/harness'. They are a bit more flexible than the common 3 inch, and some guys like that they aren't biting on ones neck. Here's a pic of some G-Force ones that have a standard seat belt buckle type lock. 79.99 Three colors, Safe Racer Company probably Summit has them too.

[Big Steve]

Dennis:

 

 

I like the color of those seatbelts. The ones aircraft spruce sells are kind of like old fords. Any color you want as long as it is black. Do they make red ones?? Steve build on

[mfryer]

I just checked out the website they have quite a few different styles and it appears they all come in black, blue and red.

[krwalsh]

If I am not mistaken the plans change to 8.5" was made because there is a risk with the plans belts of the shoulder harness being too wide and you going through the middle of the belts. On our Cozy we opted for Simpson formula car racing harnesses. They are 3" wide and they can be installed to the original dimension and be within the Simpson installation instructions.

[schmeddz]

Go to google and type in "Racing Seatbelts" Endless prices and colors. Even for picking the type of belt clips and ends.

 

Wesco Performance has Hot Pink for $59.95! (And all other colors of the rainbow. Except green or orange. Hmmmm... I feel cheated!) I had custom smoke grey colors done for my first airplane.

 

Now come the arguments against 'Non aircraft hardware.'

[ErlendM]

Is it possible to mount a 5-point racing-seatbelt in the Cozy? How/where should I attach the crotch-belt?

[schmeddz]

Is it possible to mount a 5-point racing-seatbelt in the Cozy? How/where should I attach the crotch-belt?

You would have to create/install a hardpoint somewhere in the center bottom of the seat. It would have to have substantial structure around the hard point to be effective in a crash.

I myself don't much like the thought of a strap across my privates!

[ErlendM]

I myself don't much like the thought of a strap across my privates!

I can see that one . I was just thinking that since the seat is so reclined, wouldn't the body easily glide under the lap-belt in case of a chrash or instant stop?

[schmeddz]

I can see that one . I was just thinking that since the seat is so reclined, wouldn't the body easily glide under the lap-belt in case of a chrash or instant stop?

That's a whole can of worms, although I have posted on a public forum! There is probably going to be much debate about the merits of both. There are issues of spinal compression, straight line g-loading, hard point failure, etc...

I actually do know somebody who was in a crash. They are alive and well, and I refuse to I.D. them. I don't know the specifics of whether they came out from under the lap belt. I have actually heard of other crashes where the shoulder hard points were pulled out of the backrest. But again, I haven't confirmed that.

That is a good question and I haven't done the research. I've read a few crash reports, but I haven't actually given this much thought. Maybe I would consider a lap belt after some research.

[Phil Kriley]

Just one word on plans updates: do yourself a favor and take an evening or two and write in ALL of the updates from the newletters/archives - you'll be glad you did.

[Steve Innova]

I don't know the specifics of whether they came out from under the lap belt. I have actually heard of other crashes where the shoulder hard points were pulled out of the backrest. But again, I haven't confirmed that.

 

I'm pretty sure that the plans hard-points and harness set up doesn't meet FAR requirements. Experimentals might be exempt from the FARS, but seat-belt rules are one of those areas where you would be wise to reference them.

[TMann]

Is it possible to mount a 5-point racing-seatbelt in the Cozy? How/where should I attach the crotch-belt?

Spend the extra bucks and get a six-point harness.

[Edge 513]

I can see that one . I was just thinking that since the seat is so reclined, wouldn't the body easily glide under the lap-belt in case of a chrash or instant stop?

Thats a good point. Easily gliding out and under in an instant stop. That happens all the time with thses chrashing planes. Maybe a six point would be better. A 5 point would render you impoytent in an instant stop. At the very least squish it into uselessness...yechhh- those pesky Gee-forces. After the crash in a 5 point, you'd look down and say, " GEEE, I wish that was still attached to me"...

Tmann has a 8 point.

Jerry S. has a 10 point ''web' in his SpidermanCozy he dubbed, ''Webslinger''.

Me. I just have a single point.

Right on top of my head.

[TMann]

Tmann has a 8 point.

 

Mine are siz-point.

 

......save the gnads!

[Edge 513]

Mine are siz-point.

 

......save the gnads!

Makes you wonder though about the guys using the 5 point rigs.

But this brings up my tongue in cheek point about engineering all sorts of extras into the plane for 'possible' scenarios...when the plane is pretty well thought out as it is. In the end its a experimental airplane and whatever you feel is pertinent, you are allowed to do. [i think you did a plywood under belly under your seat...or something like that].

But for the actual past # of people sliding out from under a snugged plans Cozy lapp belt in a crash...I dont think you NEED to change to a six point.

If you have sat in a Cozy, you note that the reclining position with a snugged belt wont lend itself to allowing you forward motion- unless the lapp belt breaks....because you butt is LOWER than your thighs and knees. YOU aint going forward.

[TMann]

I think you did a plywood under belly under your seat...or something like that.

Nope, I added a couple plies of kevlar to the underside of the fuselage.

 

I have a six-point to keep me in the seat more securely should my plane become intentionaly inverted and the like. It is substantially more than say the Archer I usually rent (for an example.)

 

Personal chioce, that's all. I would recommend the six-point over the five if you really think that 'extra point' is necessary.

[Vacabrava]

Hi,

I bought one 4-point Wesco red seatbelt with wrap around end shoulder harness.

I will not use the shoulders hard points, since I am not confident about then.

Instead I will fix one 1" SS tube inside the shoulder foam/glass, with 2 slots of 2" wide(separate 8.5") to wrap the seatbelt around the tube.

I will use the tube to hold the canopy latch too. Two latchs tongues fixed both sides in the FHC frame get inside the foam, through split gaps, to close the canopy holding around the tube.

Well, if the seatbelts are for car use, the thought is that if in some roll over crash when the crew remain steady on the seatbelts upside down, you can easily release the seatbelt with all the weight of one body being hold, and get free. If the latch of the seatbelt could not be released the airplane or racing car seatbelts quality are just trash, not to use nor in the childrens buggy car.

I made my side hardpoint very different, you can see that on my ch08 site.

[TMann]

I will use the tube to hold the canopy latch too.

Are these latches within your field of vision?

[Marc Zeitlin]

I made my side hardpoint very different, you can see that on my ch08 site.

Without doing a lot more analysis than just looking at you pictures, I can't be sure, but my first reaction is that your lap belt attach points are far weaker, both in the attachment to the fuselage and the pullout strength of the belt attach hole than the plans design.

 

I wouldn't fly with that belt arrangement unless substantial analysis of strength and pullout were done to compare it with the plans version, and the safety factors were identical or higher (which I don't believe they are).

 

You didn't use a quasi-isotropic layup in the mount layups (Carbon and Kevlar), so the stresses will be substantially different depending upon which direction the "pull" is from.

 

You don't have anywhere near as much glass (carbon, kevlar, whatever) distributing the load from the attach point throughout the surrounding structure - you've basically only tied the attach points to the skinny little lower longeron, which is just a weak piece of wood.

 

I don't like it at all - I think that you've substantially decreased the safety of your aircraft. Elegant? - yes. Safe? Not so much.

 

My $0.02.

[Vacabrava]

Are these latches within your field of vision?

TMann,

Sorry, but could you ask me another way? I don`t understand what is fiel of vision.

 

...You didn't use a quasi-isotropic layup in the mount layups (Carbon and Kevlar), so the stresses will be substantially different depending upon which direction the "pull" is from.

Marc,

I accept your care, and is welcome to me. To be quasi-isotropic my layup must have more two plies of 60/-60, ok?

But listen, please, I don`t finished the supports yet, Ok? I will write that on my site sorry.

I have to make more 3 plies kevlar and 2ply BID glass each side of the support extending bottom and side fuse by 4". I think like that is suitable to hold one impact. Since the plans method is one plywood of aprox. 3sq.in. laped 1" 7plies BID all sides.

You know that the kevlar do not break up catastrothic, like carbon or glass.

The support could get off the sides and longeron, but never will break. That is what I know and hope.

 

Let`s do some calcs.

Each ply of kevlar holds 200kgf/cm², with the 13ply kevlar I have 2600kgf/cm², and I have the 2plies of carbon and the 4 plies of 7725.

 

I think the concern is attenuated now, or are not?

[Marc Zeitlin]

I accept your care, and is welcome to me. To be quasi-isotropic my layup must have more two plies of 60/-60, ok?

Well, there are different methods for obtaining quasi-isotropic layups, using various combinations of +/-60, 0/90, and +/-45 angles. Usually, with +/-45's you also use an equal # of 0/90's. But as I said, there are many ways to obtain QI layups.

 

But listen, please, I don`t finished the supports yet, Ok? I will write that on my site sorry.

Got it.

 

I have to make more 3 plies kevlar and 2ply BID glass each side of the support extending bottom and side fuse by 4". I think like that is suitable to hold one impact. Since the plans method is one plywood of aprox. 3sq.in. laped 1" 7plies BID all sides.... I think the concern is attenuated now, or are not?

With that explanation and the extra plies both top and bottom to distribute the load, I would guess that you'll be fine - that's a lot more fabric to go on what you've already got.

[TMann]

Are these latches within your field of vision?

TMann,

Sorry, but could you ask me another way? I don`t understand what is fiel of vision.

 

Field of Vision: As you sit looking forward, can you see the canopy latch without turning your head?

[krwalsh]

I didn't mean to start a crap-storm with the info that we have Simpson formula car restraints in ours. We have only installed the lap and shoulder belts right now, and have not addressed or installed the anti-sub belts at this point. The one advantage of a 6 point is that you could, in theory, attach to the lower longeron and the heat duct, just like the lap belts. This would avoid the question of additional hard points in off locations.