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Learning how to build Lotus Seven replicas...together!
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PostPosted: Thu Jan 12, 2012 6:30 pm 
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Mid-Engined Maniac

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The upper side rail scares me because it's so close to the driver's head. Even a minor side-impact would be like getting hit with a steel baseball bat. The car immediately above is slighly better because the seats contain their own helmet containment. Either way it sure argues for a HANS device...

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PostPosted: Thu Jan 12, 2012 7:57 pm 
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HANS shine in front impact, for side and diagonal hits there are much better options (ISAAC)

I definitely wouldn't want a tube that close to my head unless I was wearing a helmet in a full containment seat, either way.


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PostPosted: Fri Jan 13, 2012 1:30 pm 
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The voice of reason
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Quote:
The upper side rail scares me because it's so close to the driver's head.


I worry about this in the frame I'm working on. Any thoughts on that roll bar padding? The real stuff made for that, not pipe insulation.

I'll have to do the FEA on it without the high tubes. Perhaps they should not be included on a street build, or be made removable.

Not having the upper tubes is another risk though. It's not hard to think of accidents that you would want them. I haven't been able to a deign a good tall front hoop yet, I'll have to try some more...

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PostPosted: Fri Jan 13, 2012 2:40 pm 
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horizenjob wrote:
I worry about this in the frame I'm working on...

How about moving those side diagonal tubes high enough to miss the driver's head pivoting to the side?

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PostPosted: Sun Jan 15, 2012 6:01 pm 
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I was concerned about bumper intrusion from a classic T-bone side impact. When I built my full-size mockup I found that the rear wheel provides a substantial amount of protection, depending on its lateral locating links.

Hitting a pole or a tree... I've seen several cars ripped completely in half when they hit a bridge abutment or light standard sideways. I bought one of them, a late-model Camaro that was delivered in two pieces after hitting a light standard that has claimed at least one other victory the same way, a Mustang, oddly enough. The Camaro's NHTSA-approved side impact protection was a piece of thin muffler pipe in the plastic door, which did absolutely nothing, as you'd expect.

I view a Seven as a four-wheeled motorcycle. There's only a limited amount of protection from the weather, crazies, or stationary objects. And as several people have pointed out, the cage structure itself can become a problem. And even if you solve that, there's nothing stopping something pointy from coming through the spaces between the tubes.

In the end you pay you money and take your chances. The street is a wild and wooly place compared to the safety of a racetrack.


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PostPosted: Tue Jan 17, 2012 5:55 am 
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TRX wrote:
I was concerned about bumper intrusion from a classic T-bone side impact. .


It bewilders me why Locost builders don't make some real nice looking dual side intrusion bars similar to this, nice tube and rounded bends of course, even a nice aluminium bolt on ...


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PostPosted: Tue Jan 17, 2012 8:36 pm 
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Kinda like a Sprint cars Nerf bars?

Image

Image

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PostPosted: Tue Jan 17, 2012 8:46 pm 
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Then again ...... sometimes ya just need luck ....... http://www.autoblog.com/2012/01/16/watc ... t-130-mph/

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PostPosted: Tue Jan 17, 2012 10:37 pm 
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The voice of reason
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sometimes ya just need luck


It's hard to imagine that little bar actually helping instead of just digging into the sand or dirt.

I like how in the video he says "that's odd the car suddenly oversteered then got better." A moment later it's "suddenly without warning". What did he think was happening 10 seconds earlier? :rofl:

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PostPosted: Wed Jan 18, 2012 1:29 am 
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horizenjob wrote:
I like how in the video he says "that's odd the car suddenly oversteered then got better." A moment later it's "suddenly without warning". What did he think was happening 10 seconds earlier? :rofl:
Not even in a race, not on the street, and certainly not on a track day, would I carry on after a "that's odd". I'd be off the throttle and pulling over before you can say, "I've seen enough hentai to know where this is going." You can pretty much guarantee an unexplained oddity in suspension is going to get odder.

Note the after-crash pics at the end. Our Locosts have more side protection than those Cobras.

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PostPosted: Wed Jan 18, 2012 6:57 am 
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JackMcCornack wrote:
[Note the after-crash pics at the end. Our Locosts have more side protection than those Cobras.



Yeah, most Cobra's and their replicants are just the two main rails and everything else is just outriggered off of those two rails.

Tom

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PostPosted: Thu Jan 19, 2012 7:50 pm 
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cheapracer wrote:
TRX wrote:
I was concerned about bumper intrusion from a classic T-bone side impact. .


It bewilders me why Locost builders don't make some real nice looking dual side intrusion bars similar to this, nice tube and rounded bends of course, even a nice aluminium bolt on ...


Typical American truck/SUV bumpers are higher than your top bar; they'd just go over the side and hit your shoulder. Your protection, if any, comes from the rear wheel getting in the way of the bumper.


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PostPosted: Fri Jan 20, 2012 10:57 pm 
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cheapracer wrote:
TRX wrote:
I was concerned about bumper intrusion from a classic T-bone side impact. .


It bewilders me why Locost builders don't make some real nice looking dual side intrusion bars similar to this, nice tube and rounded bends of course, even a nice aluminium bolt on ...
Mine are similar, but they're light and spaceframed because I feel for optimum protection in a book/McSorley/etc frame, it's important they not be more rigid than the diagonal tube at the side of the driver. A nice stiff side intrusion bar from materials like roll bars and rear braces (1-3/8" ERW 14 gauge tubing is what I used on my rollbar and braces) would punch right into the driver's rib cage in a side impact; you're better off with none, and hoping the other car hits your wheel.

Then why not run a brace up from the side intrusion bar to the upper seatback bar...

I was getting to that. Because a brace won't fit, the rear wheel will hit it in jounce. I'm strongly considering moving the rear wheels back 2" on my next Locost, specifically so I can triangulate the side intrusion structure.


Attachments:
File comment: How it is now (though you can't see it 'cause it's under bodywork at present).
MU53SideGuard.jpg
MU53SideGuard.jpg [ 25.57 KiB | Viewed 495 times ]
File comment: I'd brace it like this if my car didn't have suspension travel, or if the rear wheel was back a bit.
MU53SideGuardBrace.jpg
MU53SideGuardBrace.jpg [ 22.28 KiB | Viewed 495 times ]

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PostPosted: Sat Jan 21, 2012 12:15 am 
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My thought is that this is the place for an aluminum structure so that it deforms and absorbs impact before the frame deforms.

And just like a car bumper styrofoam blocks inside the structure.

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PostPosted: Sun Jan 22, 2012 9:54 pm 
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Yuck!


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crunched 7.jpg
crunched 7.jpg [ 77.62 KiB | Viewed 431 times ]

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