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Author Topic: "E" Gas Coupe Build  (Read 98317 times)

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Offline maguromic

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Re: "E" Gas Coupe Build
« Reply #270 on: October 18, 2012, 09:39:19 PM »
We got a little more work done on the Firebird today.  The headache bar and the other “A pillar bar was tacked in.  Also final parts of the firewall and the shock towers came out (I can’t believe all the spot welds and layers of metal that were used by the factory).  Also since the driver pod is going to be very stiff we designed some areas of the frame to fold away from the driver pod and not transfer the energy to the pod.  Tony 




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Offline Tman

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Re: "E" Gas Coupe Build
« Reply #271 on: October 18, 2012, 11:42:37 PM »
That is a nice cage, tight to the a pillar!

Offline Saltfever

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Re: "E" Gas Coupe Build
« Reply #272 on: October 19, 2012, 03:19:37 PM »
Re: Reply No. 265
edit . . . It was a bit of a bugger and a struggle to drill out all the spot welds on the strut towers and get them out of the way for the new front suspension and wheel tubs. Tony
Tony: This is a very interesting comment. What kind of front suspension are you going to substitute? Any links to pics of this area?

Offline Saltfever

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Re: "E" Gas Coupe Build
« Reply #273 on: October 19, 2012, 04:03:04 PM »
Re: Thread 270
edit . . . Also since the driver pod is going to be very stiff we designed some areas of the frame to fold away from the driver pod and not transfer the energy to the pod.

Tony: You have hit on an incredibly important area. I have equal concerns and have talked to various SCTA principals in the past about building-in various crumple zones to absorb some of the impact. I would like “crush” to take some of the energy and attenuate the forces acting on the driver. Everyone has been very interested and helpful but the common thread seems to support cage design as spelled out in the rule book. IOW, cage rigidity is paramount. I completely agree but there is little focus on how the rest of the car could be part of the “system”.  

In particular, I think any space between the cage and the body is a plus because that becomes a “crumple-zone” on impact. However, all cages I see are as tight to the car body as can be fabricated. Why? I could even see adding some kind of crushable material in the void between the cage and the car sheet metal to further attenuate force. I have never seen anything like that at Bonneville. Obviously, I must be wrong but what am I missing? Secondly, could you expand on your statement? I am in complete sync with you and would like to learn more. Maybe some pics or a description on how or where the frame will fold away or just additional thoughts would be valuable.

I realize this is a build-thread but your experience and approach to fabrication is high value. I’m not requesting an engineering dissertation! However, more thoughts or pics on crumple-zones would be well received. Also, I know that would take precious time so all I’m asking is to keep my request in mind and maybe address these issues as they come up along the way. Many thanks for starting this thread.
« Last Edit: October 19, 2012, 04:06:03 PM by Saltfever »

Offline hotrod

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Re: "E" Gas Coupe Build
« Reply #274 on: October 19, 2012, 04:42:51 PM »
Quote
Obviously, I must be wrong but what am I missing?

Your not missing anything on the construction side of things, energy absorption in design is well founded and used by several racing organizations in their rule packages, as are penetration barriers for racing environments that might expose the driver to "spearing".

F1 and Indy racing league require Zylon anti penetration and energy absorption panels in the chassis construction of the drivers safety cell.
Both nose cone and rear crush structures are also mandated to absorb energy on impact when the car noses into or backs into the wall. In older designs the rear trans-axle formed a very rigid structure that causes huge deceleration loads if the car backed into the wall at speed. Now they have a little crush structure that is bolted on the rear of the trans-axle to dissipate energy on such an impact.

http://www.formula1-dictionary.net/nose_cone.html

The New generation NASCAR cars have foam inserts, and a penetration barrier steel panel in the doors to absorb crash energy, and distribute loads.

http://stockcarscience.com/scienceTopics/scsCarSafety_IMPAXX.php

Energy absorption is often the only way to make protective structures survive major critical impacts.
Even radioactive materials casks include energy absorption structures so they can physically survive catastrophic impacts.

It is a very well demonstrated concept and rules packages should not make it impossible for the builder to design crush and energy absorption into the design. Unfortunately well meaning regulations that require roll structures placed as close as practical to the exterior body panels do in effect make it impossible to design into the structure planned crush and energy absorption.

Larry


Offline maguromic

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Re: "E" Gas Coupe Build
« Reply #275 on: October 19, 2012, 09:35:05 PM »
Re: Reply No. 265
edit . . . It was a bit of a bugger and a struggle to drill out all the spot welds on the strut towers and get them out of the way for the new front suspension and wheel tubs. Tony
Tony: This is a very interesting comment. What kind of front suspension are you going to substitute? Any links to pics of this area?

We wanted to look at how the air behaves in the wheel well and use the suspension components to move the air, after all the tire/wheel combo is a big pump and the air can’t be too happy in there.   Part of our solution is to move the shock and sprigs out of the air stream and to do this we will either use a push rod suspension or use the upper “A” arm as the rocker.  The hold up has been on my part designing the cage structure, as it’s an integral part of the suspension and carries the loads.  These pictures are from the net, which shows the different styles we are looking at, the last picture is of the shock on top of the frame and is from a Mustang. Tony

Push rod style


Upper "A" arm used as the rocker on an AAR Indy Car (this was very common on Indy Cars and Can-AM cars)


Horizontal shock layout with push rod activation (Used on a Mustang)
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Offline maguromic

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Re: "E" Gas Coupe Build
« Reply #276 on: October 19, 2012, 10:09:24 PM »
Re: Thread 270
edit . . . Also since the driver pod is going to be very stiff we designed some areas of the frame to fold away from the driver pod and not transfer the energy to the pod.



The rules are what they are and with .120 wall the car can drive through a wall, the way I am designing the cage it’s going to be very stiff.  The Firebird was designed with crush zones from the factory, but once we added the cage structure that all changed.  If you think about it most if not all of the loads on the cage are compression loads not shearing loads, so the driver cell will be affected in an violent event.  To minimize the force seen by the driver cell we have designed the front frame to fold away and dissipate energy if it comes down on the nose (same for the rear).  We did this by removing the metal in the areas we want to fold and replaced it with a thinner metal that would give during an event.  Part of our other straggly is as Larry mentioned crush zones on the top, side and “A” pillars of the car.  We are using the bracing to dissipate some of the energy before it gets to the cage.  Notice the roof and “A pillar bracing on this Audi DTM car.  Tony

Picture from the net.
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Offline Saltfever

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Re: "E" Gas Coupe Build
« Reply #277 on: October 20, 2012, 06:03:59 AM »
Tony and Larry, thanks for responding with the links and more information. The foam offered by BSCI in one of the links Larry provided may be worth looking into. I may consider some door panels similar to the NASCAR COT. The Audi pic also has some great ideas. In the past few posts there is a ton of information to consider.

Offline maguromic

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Re: "E" Gas Coupe Build
« Reply #278 on: October 20, 2012, 11:14:35 AM »
Saltfever, This picture is of the door protection on a BMW race car.  We are leaning towards this style with our similar door bar configuration.  Tony
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Offline Glen

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Re: "E" Gas Coupe Build
« Reply #279 on: October 20, 2012, 11:27:01 AM »
Is it flame proof????
Glen
Crew on Turbinator II

South West, Utah

Offline Tman

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Re: "E" Gas Coupe Build
« Reply #280 on: October 20, 2012, 03:54:19 PM »
A  ton of good info in the last few posts.

Offline Tman

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Re: "E" Gas Coupe Build
« Reply #281 on: October 20, 2012, 04:05:38 PM »
Is it flame proof????

Should be, the stuff passed the SFI specs. I could not get all the PDFs to open tho....

Offline Saltfever

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Re: "E" Gas Coupe Build
« Reply #282 on: October 22, 2012, 04:02:19 AM »
Glen, one of the links provided by Hotrod said the Dow foam did not support flame and did not drip. However, I was drilling around the other day and tonight I can't get any of the links to work. I can see I will be spending a lot more time researching this subject and material.

Tony that door picture (#278) really helps with ideas on how to incorporate this stuff. I was thinking more along the lines of the NASCAR COT design (as seen in the link in post #274). But I like the way the foam is being constrained with the cage on the BMW. I could see creating similar features on both front and back of the car. This is great information.

Offline maguromic

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Re: "E" Gas Coupe Build
« Reply #283 on: October 22, 2012, 11:15:17 PM »
Saltfever, I wouldn't use the foam for the front or back.  The common methods for the front and rear are either carbon fiber or honeycomb to absorb the energy.  Its not that hard to fabricate the honeycomb units and I am going to do them for the front and rear of the Firebird. This link should give you an idea of the carbon fiber units from  ycom.  Among other things they developed the carbon crash box that is currently used by the Brazilian version of Nascar. http://www.ycom.it/2011/projects/projects.htm  Tony
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Offline Saltfever

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Re: "E" Gas Coupe Build
« Reply #284 on: October 23, 2012, 07:18:49 PM »
Impressive company, Tony. But even more significant are the resumes of the principals. I would sweep their floors just for osmosis!   :-D :-D

Honeycomb is one of the first things I thought off. However, I have no experience on how to fabricate it, but most importantly, I have absolutely no idea of honeycomb cell size. I took an EAA class on composite construction so I am eager to put some of that fabrication information to work. But I lack the design knowledge to even approximate a beginning cell size. I don’t mind iterative destructive testing but have no shop to do it at the moment. I’m kind in a “holding pattern” just learning as much as I can. Also, that is one of the reasons I was considering the Dow foam since I might benefit from NASCAR R&D. However, you have presented yet another approach for a different part of the car and I am now very interested in how you are going to apply it.  I can't keep up with you  . . . :-)

I am not a big fan of using expensive carbon fiber in the LSR environment when e or s-glass could be designed with ample strength. On the other hand I haven't looked at the cost/strength trades of the materials. That is another topic I may post, but I am very busy right now and I might bring it up when I get back from SEMA.
Thanks for your continued sharing to this thread.  :cheers:  
« Last Edit: October 23, 2012, 07:33:44 PM by Saltfever »