tim
|
| posted on 1/2/04 at 09:05 PM |
|
|
roll bar height?
Anybody any idea if there is a recomended height for the roll bar from the top chassis rail on a locost. I am using sparco ultra seats. Have seen a
picture of a tiger, and the bar just clears the top of the seat!
|
|
|
|
|
Mark Allanson
|
| posted on 1/2/04 at 09:49 PM |
|
|
I think it depends what you want to use it for!
If you want it to protect you in the event of a roll, it needs to be 150mm higher than the seated height of the tallest driver/passenger ever likely
to be in the car. This is due to seat belt stretch & vertebal extension under G forces. however, in a roll, your arms will flail up and will
sustain injuries unless your roll bar is about 6' above the road.
How many seven type cars have ever rolled - I am in the crash trade and have never heard of one. I'm not saying it has never happened, but with
the CPOG of the car, I think it is a low probability.
My roll bar is for seatbelt anchorages and cosmetics - IT LOOKS GOOD!
You decide the height YOU want.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
|
|
|
Simon
|
| posted on 2/2/04 at 10:41 AM |
|
|
Tim,
I sat in the car, and had a ruler behind me head mounted on top chassis rail.
Decided how high I wanted it that way!
ATB
Simono
|
|
|
David Jenkins
|
| posted on 2/2/04 at 12:12 PM |
|
|
quote:
Originally posted by Mark Allanson
How many seven type cars have ever rolled - I am in the crash trade and have never heard of one. I'm not saying it has never happened, but with
the CPOG of the car, I think it is a low probability.
I'm sure I've mentioned this before... my son's friend managed to roll a Caterham Superlight! Extenuating circumstances: he booted
it a bit too large on a wet corner, slid, and hit the kerb sideways on the other side of the road. Also, the previous owner had set the shocks to max
resistance. He walked away totally unscathed, and Caterham repaired the car for £3K or so.
|
|
|
chrisg
|
| posted on 2/2/04 at 07:12 PM |
|
|
Asthetics alert!!!!
Nothing to do with road safety, but if your roll bar is much higher than your screen it looks silly.
If you're not having a screen then you'll need a helmet, measure to the height of you plus helmet.
Cheers
Chris
Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the
error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!
|
|
|
tim
|
| posted on 2/2/04 at 09:06 PM |
|
|
Thanks folks. Intend to put a robin hood screen on the car, but dont have it or the mesurements yet (other than its 38in wide) I also know of a westi
that ended wrong side up, car was a write off but the driver escaped with only hurt pride.
Got a friend to measure me in the car with a helmet on, (that is - I was wearing the helmet!) Looking at aprox 22in above the top rail! Looks high,
but then there is no screen on yet to compare it with. Might be best to get the screen sorted 1'st!
|
|
|
craig1410
|
| posted on 5/2/04 at 11:58 PM |
|
|
Mine is only 390mm (15.4" above the "O" tube to the underside of my rollbar. I am 5'11" and this is defintely the
minimum you would want with seats as low as possible. I'd say 17" would be a safe bet for most folk, again to the underside of the rollbar
tube.
HTH,
Craig.
|
|
|
Stu16v
|
| posted on 7/2/04 at 07:57 PM |
|
|
I suppose a lot depends on whether you want the roll bar to actually do it's job should the worst happen, or purely just 'for
looks'. Chances are even a roll bar that is above your head when you are wearing a helmet is little more than useless, unless it also has rear
brace bars.....
My bar is above my head, but at present, no brace bars. It is something that I rteally do need to sort though, especially with more track days planned
this year.....
[Edited on 7/2/04 by Stu16v]
Dont just build it.....make it!
|
|
|
craig1410
|
| posted on 8/2/04 at 11:07 PM |
|
|
Stu,
Out of interest, how high is your rollbar above the top face of tube "O" (backrest tube)? As I said, mine is 15.4" to the bottom of
the tube and about 17.4" to the top of it. I have included backstays but they are only 38mm x 16swg tubing and attach to the top rail of the
luggage rail instead of to the back corners.
I hear what you are saying about the rollbar not being as good without proper backstays but it's got to be better than nothing and should easily
be able to support the weight of the car if it did a slow roll. At higher speeds obviously it might "dig in" and experience much greater
longitudinal and lateral forces which might cause it to bend back or forwards but even then it's surely better than trying to hide in your
footwell with no roll bar at all... (Easier said that done with a 4 point harness on!)
It's also interesting to hear your experiences Mark and the fact that you've never seen a Seven roll but I used to drive go-karts (100cc
and 210cc) and managed to roll the 210cc at a decent speed so I guess no matter where your CoG is, it is still a risk. At the end of the day though,
the Seven is never going to win prizes for safety I fear, I think the best bet is to just try to go in nose first as the prospect of a side impact
scares me more than a little...
Cheers,
Craig.
[Edited on 8/2/2004 by craig1410]
|
|
|
200mph
|
| posted on 8/2/04 at 11:48 PM |
|
|
what a guy, he's even planning his crashes!!
Mark
|
|
|
craig1410
|
| posted on 9/2/04 at 12:08 AM |
|
|
I'm a true professional you know....think of everything I do!
Seriously though, I was sitting in the car the other night after I fitted my seats and was marvelling at how I could place my elbow on the rear wheel
(no arches yet) and just felt like I was in a go-kart. I then looked at the chassis around me and suddenly felt a bit scared at how little protection
the chassis gives me!
This was only in my mind because I was doing some research into euro-ncap stuff recently and I wondered just how a Seven type car would fare...
It's a sign of getting old (only 31) I think as I used to drive a turbocharged Mini like a maniac and never once thought about mortality! I even
outran the traffic police in their BMW traffic car once (allegedly ) They tried to follow me through country roads which I knew much much better
than them and although I meant to turn off up a farm road on several occasions I was always going too fast to stop and ended up running for nearly
twenty miles before hiding behind a friends house. They appeared less than a minute behind me and proceeded to search for me for over an hour to no
avail... (Ha!) I got pulled over a few weeks later for a random road check and the local police admitted that the traffic cops had told them to watch
out for a sooped up Mini with "Christ knows what" under the bonnet!! The local coppers though it was hilarious that the traffic boys
couldn't catch a little Mini...
 
Anyway, for what it's worth, I don't plan on crashing in my baby Locost. Oh no no no!
Cheers,
Craig.
[Edited on 9/2/2004 by craig1410]
|
|
|
Stu16v
|
| posted on 9/2/04 at 08:02 PM |
|
|
quote:
Originally posted by craig1410
Stu,
Out of interest, how high is your rollbar above the top face of tube "O" (backrest tube)?
I havent got the foggiest mate. If ever car and tape measure meet soon, I will endevour to find out. But TBH, your milage is gonna vary....
quote:
As I said, mine is 15.4" to the bottom of the tube and about 17.4" to the top of it. I have included backstays but they are only
38mm x 16swg tubing and attach to the top rail of the luggage rail instead of to the back corners.
At least you have backstays, which has got to be better than nowt (and mine!)....
quote:
I hear what you are saying about the rollbar not being as good without proper backstays but it's got to be better than nothing and should
easily be able to support the weight of the car if it did a slow roll. At higher speeds obviously it might "dig in" and experience much
greater longitudinal and lateral forces which might cause it to bend back or forwards but even then it's surely better than trying to hide in
your footwell with no roll bar at all... (Easier said that done with a 4 point harness on!)
I put it to the jury....if you are gonna roll a Locost, what do you think are the chances of a slow roll?
Ideally, a properly braced roll bar that is above the helmet *may* still be useless, if the theoretical line drawn between roll bar and the next
substancial construction in the front of the car is below your head.
I'm not 'preaching' by any stretch of the imagination, because as i said before, my roll bar is far from perfect. I certainly
wouldnt like to 'trust' it, unless the car was placed gently 'belly up'. And the taller the roll bar, the more likely it is
to fold without brace bars.....
However, when it is finally finished, it will be a lot more substancial than some of the 'mainstream kit' offerings, should the worst
happen.
Dont just build it.....make it!
|
|
|
craig1410
|
| posted on 9/2/04 at 09:17 PM |
|
|
Stu,
As an avid Rally fan I would say that I've seen as many slow rolls as fast ones. You know the sort of thing: Power sliding around a corner, back
hangs out just a bit too much and either clips a kerb or slides the car down an embankment. This as opposed to the car going over a "yump"
in the middle of a long straight followed by a nasty fishtail left and right and then a horrible barrel roll down the road at 80MPH...
As for the line drawn between the rollbar and the next solid object up front, if it is of any interest, I actually canted my rollbar slightly forwards
at the top just like the Caterham. The reasons are many-fold starting with the aesthetics but also including the fact that this should provide better
protection (as long as it doesn't smack you on the head) by being closer to being above the seat. I think, assuming that most rolls will occur
whilst travelling in the forwards direction, having it slanted slightly forwards should help resist bending and if it does bend slightly then it
should still be in a better position to provide protection.
Anyway, I hope none of us ever find out the rights and wrongs of Locost crash resistance...
Cheers,
Craig.
|
|
|
Stu16v
|
| posted on 9/2/04 at 09:22 PM |
|
|
Ah, but how many Locosts go rallying?
Good call on the canted bar mate.
Dont just build it.....make it!
|
|
|
200mph
|
| posted on 9/2/04 at 10:14 PM |
|
|
I suppose though, were the worst to happen, assuming the line from roll bar to next point (probably somewhere on bonnet/scuttle) would bisect the
head, at least with a roll bar this would be compensated for by the neck. The bend, although it would probably cause some damage, could be absorbed
by the neck.
If the same roll happened with no roll bar, it would be curtains, undoubtedly.
havent worded that very well, but I'm sure you know what I mean..
rollbars: never leave home without one
Mark
|
|
|
fastavatar.jpg){kind=avatar}
