LocostUSA.com

For the builder on a budget, it would seem that the cheaper EPS* foam board insulation might actually have somewhat better overall impact energy absorption properties than XPS** foam board insulation...But details about this are admittedly a bit thin on the ground. While maybe not the 'best' option available, it sounds like it may still be one of the best bang for the buck.


*Expanded PolyStyrene (EPS)...The white foam board made up of many small individualbeads of foam.

*eXtruded PolyStyrene (XPS)...The blue or pink foam board with a smooth and uniform composition.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

http://www.indycar.com/Fan-Info/INDYCAR ... ifications

EPP foam.

The IndyCar "seat" is molded into the tub, as are most open wheel cars and WEC prototypes and such (or so I assume?). Which it seems to me is about as rigid as you can get.

But the teams puts a bag of foam beads on the monocoque, then seats the driver on the bag of beads, and once the driver is comfy they mix up the resin/hardener and pour it into the bag o' beads. The driver sits there until the foam is all solid.

https://www.youtube.com/watch?v=0Hl1clLoOuo

From that beginning, the seat "insert" is then contoured and fixed and fixed and such, until the driver is happy, at which point it is covered in tape (friction tape?). Kinda strange seeing a driver's name written on duct tape or white tape (or duck tape?), on a foam insert that is cover by tape, decidedly not real polished-looking.

https://www.youtube.com/watch?v=mXEfWZd4LBo

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***************
Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Out of interest I wondered if the downforce on the car was a factor in the suspension fail. The car was already fat with a V8, is it possible the wings were overloading the suspension while riding kerbs etc?

Bob

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Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave

I would bet that most of what those wings are doing is reducing the lift inherent to the Lotus 7 shape. Even if the wings are powerful enough to create a small amount of net downforce over the loads seen at rest, I doubt if it would be significant in comparison to the forces exerted by road irregularities.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Though I haven’t posted here in quite a while, I check in occasionally to catch up with what’s current. I just ran across this post and first of all, I’d like to extend a thank you to all of you who have wished me well with my recovery. I’m currently enduring week sixteen in the brace (with several more to go) all in the name of avoiding surgery which would require entry through my chest as well as my back and would require having a heart surgeon involved; and another twelve weeks of recovery. I’m trying really hard not to go there. And hopefully, I’ll be back in the air soon instead of simply flying a desk….and, hopefully, back to driving again.

While I’m here, I’d like to clarify a couple of things. First, the fracture on the a-arm mount was a fresh fracture, caused by impacting the pothole. There was no ‘failure in progress’ prior to the accident and for those who have questioned the discoloration present in the photo/s of the mount, it is, indeed, dirt. Below, I’ve added a photo of the lower a-arm bracket on the RH side of the car. You can easily see the fracture of the mount; though now discolored from sitting on a lift for three months, it’s was, at the time, a fresh fracture and happened once the car impacted the ground; this was after becoming airborne.

Secondly, I spent quite a bit of time compiling and creating the accident information all for the sake of safety, so that ALL who share the same passion for driving might gain something constructive from my experience. For those who are interested, here is an additional link to a USA7’s thread regarding my accident:

http://www.usa7s.net/vb/showthread.php?10354-XCarGuy

I did not, however, spend weeks analyzing and editing this information for the sake of being criticized for entering an apex too early and then choosing to power out onto the rumble strip and then off the pavement at the exit while carrying a passenger who also happened to be an instructor. Frankly, there was no pavement to run off of at the end of the rumble strip because the track had deteriorated and was no longer there. The person who made these comments is the very reason I stopped posting on this site for the most part, and those comments are a shinning example of why I chose not to share my information about my accident on this forum. But for those of you who have stayed on topic in this thread, thank you. This was my first time running this venue, and if the video is reviewed in its entirety, it is evident that during the next three laps (after hitting the pothole) leading up to the accident, I (early or not) come off the apex and stayed well clear of the rumble strip. Photos of the deteriorated track surface are also in the video.

As a professional pilot with 10,000 plus hours and many years of accident and incident free flying, as well as the current aviation department safety officer for a fortune 100 company, I can assure you that I absolutely do not do 'haphazard' well. Every component of every aircraft should be given the same attention to detail during a preflight for the first flight of the day......EVERY COMPONENT....EVERY PREFLIGHT. And if you choose to drive your car in a high performance environment, it deserves the same attention to detail before getting on track…..EVERY TIME. A tech inspection, by comparison, is cursory. Be thorough. If I sound preachy and condescending, my apologies; sixteen weeks into recovering from a compression fracture, a burst fracture (and two other fractures) and dealing with daily pain had made me a bit of bear to be around. More importantly, it motivates me to stress the importance of practicing safety, in the hopes of passing something positive on to others so that they may avoid what I'm currently enduring.

Its great to see you sharing the knowledge in hopes of preventing it from happening again - thanks.

Thanks for checking in and keep hanging in there. You'll be back in the saddle before you know it.

_________________
-Andrew
Build Log
Youtube

Keep us posted of what changes you make to the chassis on your next build in light of this accident.

So what ya gonna do now? I mean once you are mobile again.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

While I'm already planning what I consider (or at least hope) to be a relatively safe build, this valuable information has definitely caused me to make some changes to those plans that should provide an additional degree of improved safety, and sounds like it might do the same for some others here as well. So in my humble opinion, I think that should be more than enough to make it worthwhile to share here as well, even if it means dealing with some criticism outside the scope of your intentions. I really do appreciate your candor in sharing your unfortunate (and extremely painful) experience, even if not originally directed towards this site.


Please don't take this as antagonistic, as I think this is simply another area of concern that further discussion could be beneficial to the community. I am honestly curious what makes you so certain that there was absolutely no possibility of any crack formation in the heat affected zone next to the weld before hitting the pothole? The early initiation of fatigue cracking in the heat affected zone are not necessarily going to be easily spotted in black coatings, and may not even be visible under thicker coatings. Now don't get me wrong, I'm not saying that a tiny crack would necessarily have had to already begun forming there either, but I don't see any evidence pertaining to just how fatigued the heat affected zone on that particular of bracket was (or was not) before the impact.

Either way, regardless of fatiguing or not, the photograph basically shows the bracket failing in the exact location and exact manner as expected. It's a reasonably well known shortcoming of that type of bracket mounting scheme, with a demonstrated history of failures. Even without any crack propagation, if it had any degree of fatigue weakening it prior to impact, some might still consider that to be a sort of "failure in progress"...Just a longer term one, if it hadn't been for the pothole. If you are in, or expect to be in, any communication with the manufacturer regarding this incident, I think it would certainly be a worthy point of discussion with them for future improvements to the long term durability and overall strength of the design...Since that could have the potential to prevent such failures from injuring (or worse) other Stalker drivers/passengers in the future as well.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Thats how I see it and will be addressing this in my build. I cant agree with this dispensable wishbone mounts/lugs to save bending the chassis ethos. Sod the chassis its only a lump of replaceable steel , those lugs/mounts,wishbones and hubs need to stay on the car no matter what is driven over.

Bob

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Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave

I said, simply, that it was a fresh fracture. As to how I came to the conclusion, after the fact, that this was a fresh fracture, with no previous fracturing having been present, was by applying the knowledge I’ve gained over the years through the study and review of aviation accidents; as stated earlier, I’m the safety officer for my company’s aviation department, and aviation accident review is part of my job. Some of the accidents I’ve reviewed were caused by metal fatigue. Once metal begins to fatigue, it will begin to fracture. A fracture, over time, will exhibit signs of wear and corrosion in the affected area. The fractures and breaks were both clean (sans the dirt) and neither showed any sign of wear (very sharp, crisp edges on both sides of the fracture with no deformities) or corrosion (rust) in the area in question. The total damage to these mounts occurred that day,; first, after impacting the pothole which was followed by impacting the ground after a four foot drop.

Thanks for clarifying your background in identifying metal fatigue crack propagation. I expected, or at least hoped, something like that might be the case.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Thanks for posting information on this unpleasant event. I put thought into how my seat would move in front,rear,side impacts, but I never considered severe downward impacts. I kind of assumed that the suspension will take up enough of it, but there is nothing saying in a wreck your wheels are what will hit first (or even still be intact). I will definitely look into some foams. My suspension mounts are massively overbuilt, but I wanted to be able to abuse this car and not have to worry about exactly these sort of failures.

I hope you back heals well, and doesn't leave any long-term issues.

Cheers.

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Build log: viewtopic.php?t=9291

This is as good a picture as I can find, but would a UCA mount like this have fared better in your crash?



The picture came from here.

https://www.facebook.com/media/set/?set=a.10152625776619942.1073741841.383242759941&type=3

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

I truly couldn’t say with any certainty. The pothole and the associated deteriorated portion of the track located at the end of the rumble strip left a 2-3” deficit between the eroded area and the actual surface of the track. It was a very hard hit at just under 100mph.

This is where I beg to differ. That lug welded to the chassis is being hammered in just about every plane. Under braking with the torsional twisting and over bumps, it`s failure in my eyes is inevitable. Having the lug hanging off the side of the chassis like that is a failure waiting to happen and believe the outside portion of the lug should be braced back to the chassis. I think that the bracket has work hardened to the point of becoming brittle and sheared of when the car hit the pothole. Hence the clean break, its not torn off its a fracture.

Bob

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Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave