Geo

Was it homologated with the back brace installed?

Also, the SCCA only requires a back brace be used on seats that do not carry the current FIA homologation.

Thanks for the splendid information on that seat. It will figure into my safety gear at some point, but like most people, I have to make compromises. This year my big addition is going to be a HANS.

BrandonH

From the Tide/Downy racing site, some interesting specs on their PPI seat. Sounds like the seat I want.

Seat

Purpose:

To reduce driver injury in stock car racing accidents


Designed by:

PPI Motorsports and Reynard Motorsport



Consultants:

Ford, Dr. John Melvin, Gordon Coppuck



Manufactured by:

Reynard Motorsport, U.K.



Distributed by:

C&R Racing Incorporated, Indianapolis, IN



Approved by:

NASCAR, January 2002






Seat Construction
› Aluminum honeycomb with carbon cloth applied to both sides
› Bead foam head insert that surrounds the driver's head
› Six-point restraint system mounted directly to the seat
› Energy-dispersing bead foam body insert custom-fitted to each driver
› Optional integrated foot box
› Standardized seat and seatbelt mounting
› Layered with Gentex to resist heat transfer to the driver
› Layered with Dyneema to resist intrusion of objects
› Cannot be modified by individual drivers/teams
› Symmetric — same protection for driver and passenger side impacts

Why Composite v. Aluminum?
› Testing showed standard and reinforced aluminum seats do not yet withstand multiple impacts like the composite seat.
› Testing of composite seat for frontal, rearward and passenger lateral impact — incorporating Willans six-point restraints, HANS restraints, bead foam head and body inserts — showed impact loads well above survivable
› More rigid — prevents belts from loosening during impact
› Higher fatigue resistance
› Will always try to return to its as-made shape
› Will not crumple and injure the driver as aluminum can
› Lighter — composite seat is up to 8 lbs. lighter than a comparably equipped aluminum seat

http://www.tide.com/tideracing/teamt...rix/seat.jhtml

fatbillybob

snip..."interior safety net"...

What does an interior safety net look like? How is it set up to catch your body? Any pictures? I have never heard of this before. Is the net specfic to a particualr seat or can any seat be retrofitted?

924RACR

See the other thread that I started about the Tom Gideon presentation. I have pics of the relevant net in my car on my homepage.

robmug

I've been involved in FIA testing of composite race seats. The FIA test conists of 3 parts, all which must run concurremtly, without modificatio to the rig.

A bare seat shell (no padding or cover etc) is mounted to a rig, and a 50th percentile crash test dummy (75kg) strapped in with full race multi-point harness.

The rig is then fired to simulate a 25g deceleration in a backwards direction. (ie with the driver backwards). A forwards impact only tests the harness. The onboard acceleromiters must record a minimum of -30g for 50ms continuously. The second part is a sideways 10g yest, followed by another rearwards at, if my memory serves, 15g.

The seat shell must be undamaged after these 3 tests.

High speed video footage is incredible, and it is the flex of the composite seat that actually helps the driver.

I've not tested an aluminium seat, but the mounting of any race seat is critical. If there is something solid behind the seat (roll cage, bulkhead etc) then this reduces the rearwards travel of the seat under all circumstances.

A FIA seat is designed to be mounted at the base only, and to withstand any impact rearwards, even if there is absolutely nothing behind the seat. What the FIA test is trying to do is to stop the seat breaking.

As you can imagine, restricting the rearward movement of the seat by attaching it to a bulkhead or rollcage makes the seat much safer, and therefore, the seat doesn’t need to be as strong. It’s the rollcage that needs to be strong.

If it were me, I’d use a FIA seat, mounted to the rollcage! Best of both world.

I’d be interested to know how the aluminium seats are tested…

Geo

Excellent information! Thank you.

I have one question however. You've left me with some confusion.

You state that you'd mount the seat to the cage to restrict rearward movement, yet you previously stated that the flex of the seat actually helps the driver. Can you reconcile these two statements for me?

Oh, and one other question.....

If my neighbor can do the welding this weekend, the cage is going into my car this weekend. I haven't mounted the seat, but it appears to me that I will have roughly 18cm between the back of the seat and the cage. Is this insufficient space to account for the flex of the seat?

924RACR

Hear hear! I'd also like to point out again that, as you've mentioned, the pass/fail criteria for these seats is only the condition of the seat after the tests are complete. While there may be seat flex, and it may help reduce loads on the driver, this is not part of the testing, and certification of a seat by the FIA does not say ANYTHING about the loads on the driver/test dummy during these tests.

Have you been involved in any other FIA certification tests? Harnesses or H+N restraints?

robmug

Geo - The flex helps the driver by effectively inreasing the distance over which the loads are applied. The bulkhead or roll cage help by preventing, under any circumstances, the seat collapsing.

18 inches is plenty to allow for the seat flexing - it only moves an inch or two.

...remember also that you're very unlikely to hit -25g backwards...

924RACR - I agree, the FIA tests fall short in my opinion. There's no grey area in the regulations, and they fail to take into account, for example, how the seats are mounted, yet it is the mounting that takes a lot of the force of an impact. I know one UK manufacturer who is considering selling FIA seats only with approved mounts. I think it is also unrealistic to test a seat without padding.

I've not been actively involved in any other FIA testing unfortunately. Ultimately, the regulations are a good thing, even if they fall short of a perfect set. I'm in no doubt that a seat carrying the latest FIA certification is better than the 'old' static testing that they used to do.

Geo

Thanks for the info. The distance is actually 18cm, not inches, but appears to be enough. Makes me feel a whole lot better.

M758

Ok so now that we have some info on how an FIA seat gets its FIA stamp... What Standards to Aluminium Seats meet. I know there is the Viper Comp seat tested to 42g's by its manufacturer I assume in some maner of rear impact. What about the other popular Aluminum seats?

So it would seem that all FIA seat meet a minimum the above testing. Some may be better, but this is not easily determined from that testing. I does also appear that some Aluminum seats are tested to higher loads, but are all aluminum seats tested to at least some standard?


I guess this issue with Seats and H&N devices. The goal of True indepentant testing by groups like the FIA, SFI, and Snell are designed to show that Product X meets at least a minimum standard. Therefore when the racer goes out to buy they know that they are least protected to level set forth by testing in XXX org. I do NOT think it is goal nor should be of these orgs to find the BEST device. Too much politics involved, but they should develop tests that are based on real world conditions and then only approve products that meet or exceed them.

924RACR

Very interesting that you should say 25g is unlikely! What are likely values, and under what circumstances? As long as you're not running on a concrete oval?

JCP911S

Great info... these safety threads are addressing some serious issues that I think have not been given enough attention.... keep it up... good info on the FIA tests

One pet question of mine that we still have not addressed head on, and that is hard mounting the seat to the cage provides virtually no "give" in the event of a hard rear impact.... (assuming that your body won;t deflect the cage much is probably a safe one IMHO)....

FIA seats are designed to deflect... this reduces peak g-loads the same way stretching of harnesses does in a front collision... I have to belive this is a good thing in terms of overall survivability.

If steel harnesses are a bad idea... and I suspect we all agree they are... why is a seat mounted to the cage a good idea?.... just a rhetorical quesion

In the event that the seat does break, having a seatbrace as a last line of defense before hitting the harness bar of the cage seems like a smart precaution... two layers of protection.

JCP911S

PS... clarification of above.... the seatbraces should be mounted so as to give the FIA seat maximum flex room.... I have mine about 4 inches behind the seat... but 18 cm is over 7 inches using my bad math.... thats alot

924RACR

Wrong. Sorry, you're stating an assumption as a fact here. In actuality, while the composite seats (FIA-approved or not) DO flex in an impact, this does not mean they are necessarily designed to flex! This does not mean that the flex is required to receive FIA certification! This is exactly the assumption that so many people have been implying in these discussions!

If A then B is not the same as if B then A!!!

I have no arguments with your speculation that this may improve surviveability, or with the desireability of some stretch in the harness. I would, however, challenge an assertion that flex is designed into the harnesses, particularly with respect to the FIA certification. I did not finish reading the FIA cert procedure for belts, but I doubt (based on reviews of the FIA certification for seats and the HANS device) that it does.

All that said, I can't help agree with my casual speed-reading of your last comment, about (the sanctioning bodies) having two layers (lawyers) of protection in event of a hard impact... (my additions in parens)...

Just trying to clear up some of the inaccuracies that continue to resurface... and to improve the signal-to-noise ratio in these safety discussions.

JCP911S

924... yes your are right...technically nothing in the FIA spec "requires" the seat to flex, but in my actual experience most of them do... flexible materials will absorb KE with less max G-Load than hard materials.... it is my assumption that this is the way most manufacturers have chosed to meet the standard.

It is the maximum "point" G-load that determines injuries, not G-Sum (if you'll pardon me...)

Harnesses are designed to stretch.... this from Simpsons web site:

"Through testing, we have found that there is a delicate balance between force and elongation of the webbing. Traditional standard nylon webbing available in the U.S. has elongation (stretch) of approximately 15% to 17% at 2,500 lbs."

Bobmug... does the FIA test have the accellerometer on the sled or the dummy....? Be interesting to see if the G-Load is different...

Again I am no phycisist, but I have a hard time believing that attaching the seat directly to the cage reduces max G-load in a rear impact... the seat breaking does not hurt you... its what you hit after it breaks that hurts you.

That said, spreading the load over a larger surface should help you... if a deformed seat concentrates the load on one point, that is not good.... either.... seems to be a tradeoff here

I am not stating facts or even assumptions... just asking the question... because it is an important point and there seems to be a variety of opinions on it....