Important thoughts on safety (how to avoid actually testing your firesuit)

[Racer28173]

A couple of old and/or inconsequential threads inspired me to collect some thoughts in a place that people are likely to find it.  I will start with the high level point and then include some supporting info.  A shout out to @skierman64 and @Hi_Im_Will for their input on this.

 

SUMMARY:  All car owners that don't have rear "glass" installed (i.e. lexan) should strongly consider installing it.

 

Reasons:

• It may save a life.  The lack of side and rear windows causes the windshield to create a low pressure area where the driver is sitting and can suck fire (or Carbon Monoxide) into the cockpit.  This isn't a hypothetical - both have happened and one of them was a very close call.  Had the car owner not been young, nimble, and very familiar with his car, he would have been badly injured or killed.
• It may make your car faster.  In almost all cases, you will reduce drag by putting the rear "glass" back in.  (Note, I am not talking about cars that have no front "glass").
• It drastically reduces the amount of rain/mist that swirls into the cockpit, and will make driving in wet conditions safer and more enjoyable.

 

There are reasons why the rules used to tell you to remove your glass, but events that have happened since then have provided data to suggest that the reasoning was misguided.  I'm not going to write a novel on that - you can find it in other posts if you choose to look for it.

 

I wasn't sure if just putting the back window in would do the job, so I consulted with Will.  He shot me a bunch of impressive stuff and an interpretation that said having the side glass gave some benefit, but the vast majority of the benefit could be gained by the installation of just the rear glass. 

 

Here is the link to what happens if you don't have any glass other than the windshield and you have a fire:

 

 

Here is some more of the backstory.  It was posted in an E36 thread so I can't imagine very many people were reading it 

 

@skierman64 added this to the thread:  "Oh, while you're at it, make sure all the holes in your firewall are sealed with some kind of metal or at least metallic tape.  There was a under hood fire at COTA last year that got into the cabin of the car through firewall holes.  The driver suffered some significant burns due to someone not prepping the car properly and sealing up firewall holes before the race."

 

Here is the link to that incident, as well as a thread that went into the topic pretty well

http://sopwithmotorsports.com/blog/short-track-racing/item/342-trapped-in-a-burning-race-car-part-i.html

If you decide to blow off the suggestion, you may still want to consider getting this for your cockpit (thanks @Jamie).  It will let your driver figure out whether or not the stuff coming into the cockpit will kill him (not fire, Carbon Monoxide)  https://www.amazon.com/Quantum-Multi-Level-Carbon-Monoxide-Detector/dp/B003UDAHIO/ref=sr_1_1?ie=UTF8&qid=1488932145&sr=8-1&keywords=carbon+monoxide+detector+for+car

 

My final safety item for the evening:  I saw a car at VIR that had the fuel filler almost straight above the side-exhaust pipe.  I assume they located the filler there (it wasn't the stock location) because they wanted to have the filler on the side nearest the pit wall (most tracks, that will be the passenger side).  I assume they decided to exit the exhaust on the passenger side because it made for slightly less noise for the driver.  Both decisions make sense when made alone, but when the inevitable "small spill" occurs we will have a very ugly situation on our hands.  Please look at your car and make sure you aren't at risk for what follows below (OK so I MIGHT have exaggerated on this one!)

 

 

In all seriousness, if the spill happens and a small fire ball erupts, the gas man could drop the dump can which would provide a LARGE fire ball that could affect a lot of people.

[Ron_e]

So just to be clear, FYI not all vehicles have the same aerodynamics.  You can choose to put in a rear Lexan rear window or not.  If you have an underbody fire and no Lexan rear window you may or may not get fire into the cockpit, you need to assess this yourself.

 

Take for example the Miata which has a windshield but is not known as a firetrap - with or without a rear window or hardtop.  Another example is our Mustang, we have turndowns before the axle and if we had the aerodynamics to suck underbody exhaust into the cockpit I would be installing a rear Lexan window to help prevent that and fire path as well.  We do not have exhaust odors so I am not installing a rear window.  We have raced in the rain without a rear window and our drivers stay dry, occasionally I have noticed some mist on the back of the windshield but it was usually in traffic with spray in the air from other cars alongside.  This would be a low pressure area behind the windshield but it seem to suck in from the sides rather than the rear - maybe our Mustang has a weird aerodynamic I don't know, I do know it has horrendous aerodynamics overall.

[Racer28173]

3 minutes ago, Ron_e said:

So just to be clear, FYI not all vehicles have the same aerodynamics.  You can choose to put in a rear Lexan rear window or not.  If you have an underbody fire and no Lexan rear window you may or may not get fire into the cockpit, you need to assess this yourself.

 

Take for example the Miata which has a windshield but is not known as a firetrap - with or without a rear window or hardtop.  Another example is our Mustang, we have turndowns before the axle and if we had the aerodynamics to suck underbody exhaust into the cockpit I would be installing a rear Lexan window to help prevent that and fire path as well.  We do not have exhaust odors so I am not installing a rear window.  We have raced in the rain without a rear window and our drivers stay dry, occasionally I have noticed some mist on the back of the windshield but it was usually in traffic with spray in the air from other cars alongside.  This would be a low pressure area behind the windshield but it seem to suck in from the sides rather than the rear - maybe our Mustang has a weird aerodynamic I don't know, I do know it has horrendous aerodynamics overall.

I will let someone who has studied aero more than I have comment on why the hardtop Miatas wouldn't have this problem.  I have to admit that I was focused more on normal sized cars with permanent roofs and full-size real windows.

It would be interesting to know if the "sucking air from the sides" on your Mustang could be reduced with the installation of rear "glass".  With air coming in from the sides in a big way, you probably still have the risk of pulling the fire in if it happens because the fire is likely to be forward of the windows (whereas your exhaust is likely exiting behind the windows)

[Ron_e]

2 minutes ago, Racer28173 said:

I will let someone who has studied aero more than I have comment on why the hardtop Miatas wouldn't have this problem.  I have to admit that I was focused more on normal sized cars with permanent roofs and full-size real windows.

It would be interesting to know if the "sucking air from the sides" on your Mustang could be reduced with the installation of rear "glass".  With air coming in from the sides in a big way, you probably still have the risk of pulling the fire in if it happens because the fire is likely to be forward of the windows (whereas your exhaust is likely exiting behind the windows)

 

This is a side view of a notch Mustang, same as ours.  When I said mist I meant to say very light mist as in hardly noticeable, and only when other cars are along side.  I highly doubt adding side rear windows would change this and it is of very little concern.  If it was sucking fire from underneath the car and into the side windows then I would be wishing I didn't have a rear Lexan window as I would be looking to that as my escape.  As you can see our exhaust dumps would be at, or in line with the rear windows but underneath the car, as well the rear windows are quite small.  We do not get exhaust odour in the car.

 

Just saying - everyone needs to make their own assessments on the need for a rear window in their particular car.

[skierman64]

I applaud @Racer28173 for this post.  In the vast majority of cases, side (aft of the driver door) and rear windows will keep the bad stuff out and give you room to live.  I ask that all consider lexan as a safety improvement.

[BigMoneyWasters]

The WRL requires rear windshield be installed, even original glass one. I assume this is why.

[tommytipover]

I always thought the no-glass rule was silly.  I figured it was an artifact left over from the Condren, LeMons, Altamont-crashfest days.  For some reason little oval tracks are afraid of tempered glass, and for that matter antifreeze, road racers have been racing with those things for years.

[csadn]

5 hours ago, tommytipover said:

  For some reason little oval tracks are afraid of tempered glass, and for that matter antifreeze, road racers have been racing with those things for years.

Reasons I can see: First, unavoidable contact on ovals is a bit more prevalent than road courses, which makes it more likely a window will get popped out, or a radiator line knocked off; second, lap times of around 17 sec. mean if a window or fluid does comes out, there's that many more cars which will be forced to deal with it; third, cleanup is a PITA.

 

FWIW: I never agreed with the no windows rule; but it wasn't my place to comment on it. (I'm not a fan of it at the short-ovals either, having seen similar effects to what's shown in the OP even at those speeds.)