Exocet vs Elise

In reply to codrus:

True, but you get my point. A theoretically ideal space frame each element would only see pure tension or compression.

DaveEstey wrote: In reply to Keith Tanner: Nobody has shown up with a Caterham or Atom and tried to pass tech inspection. We can wax philosophical, but tech guys get to say yes or no. The Exocet gets a no for us with its current design. Shame, because one of my favorite competitors bought one and can't race it with us.

With as many racing series not in the US running Caterhams/Locost, Atoms and Exocets I would also like to know the reason for failure. Not trying to start anything on this thread, but I would question the officials on that one. I would want a detailed explanation as to why it failed. You know, to make sure when I return it passes.

If the guy had a base, I get it, if he had a sport, eh borderline on that one, but the race model, I can't see why the chassis would fail tech.

In reply to Adrian_Thompson: I already said that somebody had been actively turned away.

I know the tech guys well - they don't turn away racers, especially the guy they had to with the Exocet, without having safety concerns. Both parties know and like each other and have been doing this a long time. To assume someone is being sanctimonious is just being combative.

We should also be aware that Hillclimb is not road racing on a track - it's tarmac rally where the runoff is trees, boulders or a long drop. The protection necessary for these events exceeds that of normal track work.

The above referenced Caterham designed is braced far more heavily across the floor.

That's tough for that guy turned away. If it helps the race chassis has steel plate floor. I wouldn't suggest the tech inspection guys are wrong. They are just doing thier jobs and following the rules. If it were me I'd appeal to the sanctioning body to take a look at my specific vehicle. Have them look at the car or send pictures and approval of the other sanctioning body that is to thier standards. If they deem it unsafe then your just stuck. It just seems like this might be a safe vehicle that's being caught by a wide net (that's there for good reason for the majority of other cars). Hopefully the guy can eventually do what he wants with it.

Adrian_Thompson wrote: In reply to codrus: True, but you get my point. A theoretically ideal space frame each element would only see pure tension or compression.

Sure, but cages are also designed to take impacts, and some tubes will see bending loads from unusual angles in that situation (the ones that actually hit the tree or whatever). You can upsize the square tube to give it a minimum strength the same as the round tube, but then it gets even heavier.

(But I agree it's not really relevant to the question at hand)

This not passing rules thing is bothering me. So I pulled the rules.

There are a few things the Exocet might come up short for but nothing that couldn't be addressed by the owner.

AA. Construction
1. In absence of full factory steel floor and firewall, chassis structure must be reinforced to prevent driveline intrusion into driver's compartment.
2. Driver must be guarded from driveshaft.
3. Front driveshaft loop required on rear-wheel-drive cars.

D. Interior and Trunk
11. Cars must have at least 2 sections of side protection. Roll cages must have at least one bar in the door area. Stock door beam found in most cars is acceptable as a section, as is a substantial outboard frame rail or rocker panel.
12. Protection for the foot well area, and from “drive train intrusion”, (as in 3. AA.1) must be incorporated into the chassis/roll cage structure. Full, continuous (stamped, OE) steel floor is considered adequate.
13. Energy absorbing features must be incorporated into the chassis structure ahead of the driver’s feet, and to the side of the driver.

Adding some honeycomb core aluminum sheet in the right places would fix all of this.

In reply to Schrödinger's Flight Service:

I get how a stock car with a cage still has the energy absorbing structure in front of the driver that an Exocet doesn't, but a gutted door with cage bars against it offers little no energy absorbing features.

In reply to MrJoshua:

I am not debating the effectiveness of the rules compared to their intent, just the rules that would deny an inspection sticker

First for Tuna55 if you are not aware of it already Datsuns are 6-8" narrower than a Miata. My friends Exocet is frequently parked next to my Datsun 1200 at track days....you'd be amazed how much bigger the Exocet is than an old Datsun.

@Schrodingers Flight Service back tracking and off on a tangent, those motorcycle videos you provided are backwards to what you intended; the young Finn riding side saddle on the Moto 3 bike pulled of one of the most saves ever. I can slide a production bike all day long on dry pavement, it isn't that hard at all (obviously doing it at a much lower level the the MotoGP video linked). As someone who road raced the 125 class (albeit as an amateur) these small bore GP bikes (even 50hp 175lb 250cc Moto3) do not have the raw power to keep the bike sliding, they slide for a ways then the back hooks up, which violently loads the forks, the whole mess bottoms hard and spits you off.......the young Finn actually did this and hung on.

Whoever mentioned gutted doors; I have a rally spec cage in my back but intentional left the full door because the door offer a good bit of impact absorption. I do realize bigger drivers don't always have the option.

Finally back on topic; I'd go with an Exocet, I've driven both vehicles on track. The Elise is amazing to drive but as was mentioned the Exocet just brings out that hooligan factor. On the 3.4 layout at Spring Mountian Motorsports you can go flat through the last part of the esses but you arrive at the 90 right turn 5B way to fast, in the Exocet you just brake chuck it sideways on turn in and scrub off the needed speed. It's hard to put a price on that kind of fun, couple that with the low price of an Exocet and you have a win win. Naturally this is my totally biased opinion.

As for the looks and aero; I often wonder if you could fit EP or GTL Miata fiberglass panels to the Exocet. Either that or come up with a shape similar to the old Panoz front engined prototype.

MrJoshua wrote: In reply to Schrödinger's Flight Service: I get how a stock car with a cage still has the energy absorbing structure in front of the driver that an Exocet doesn't, but a gutted door with cage bars against it offers little no energy absorbing features.

Door bars in a cage, if done correctly, are energy absorbing. The point of a cage isn't to be rigid, it's be the compliant in the right ways.

DaveEstey wrote:

MrJoshua wrote: In reply to Schrödinger's Flight Service: I get how a stock car with a cage still has the energy absorbing structure in front of the driver that an Exocet doesn't, but a gutted door with cage bars against it offers little no energy absorbing features.

Door bars in a cage, if done correctly, are energy absorbing. The point of a cage isn't to be rigid, it's be the compliant in the right ways.

I was referring to the energy absorbing structure to the side of the driver requirement. The exocet has "door bars" like a caged car. The door skin offers more intrusion protection, but not a significantly greater amount of energy absorption to meet that rule.

In reply to MrJoshua:

Significant wasn't the rule...

In reply to Schrödinger's Flight Service:

I'm probably trying to put logic to rules across different classifications and that rarely works. The rules are centralized to the average entry into a class. Production cars are good at energy absorption and open wheel cars are not so they require open wheel cars to add an energy absorption layer in front of and to the side of the driver. In this case I think the gutted caged production car and the exocet overlap but if the rules don't agree it really doesn't matter.

In reply to MrJoshua:

When I was doing F2/F3 boats we had a rule change to say the nose cones of the capsule had to have impact protection to prevent penetration into another capsule in the result of a collision.

So we made a mold of the tip, cut it off, glassed-in a flat back wall, glued a deflated bouncy ball in there and put a super thin cover over it from the mold we took.

It was a weekend worth of work and read to the rules. Now was it to the intent? No. But it did follow the rules.

All because someone spun, got t-boned and had a capsule piercing.

A lot goes wrong in boat racing that has to be tolerated due to the conditions, but capsule intrusion isn't one of them.

As far as the ball, we haven't had a capsule pierced since as far as I know.

I get a thin piece of metal on either side of the exoskeleton seems silly, impact protection in front of the driver's feet is an extremely open statement.

A thin sheet of aluminum and a front wall of aluminum honeycomb instead of sheet metal would fix all of this.

The honeycomb would actually do what the rules intended too, better than a rubber ball.

In reply to Schrödinger's Flight Service:

I think everybody would get a laugh if somebody did the honeycomb and then taped a rubber ball on the side of the car as well.

Unfortunately, an Exocet owner decided to provide an example for us today. That's a Sport frame, the Race would have the upper part of the cage as well. That's pretty much worst case for a side impact. I've seen this same hit on a Miata, although I have no idea of the relative speeds. This car was at "a decent rpm" in fourth. 4th is 16.7 mph per 1000 rpm, so you decide what "decent rpm" is.

Driver is "bruised and sore".

In reply to Keith Tanner:

Oof. Looks like that sucked.

And that, campers, is why I decided not to do any more track days in a Lotus 7 without added side impact protection. Can you imagine if those were two 1 1/4" x 18 ga square tubes right up against the drivers hip?

Holy E36 M3....

Any conjecture on how much better/worse a race chassis would've been? I'm assuming they had a helmet on...

I has a solution...

Edit: That is already 7 supplied.

accordionfolder wrote: Holy E36 M3.... Any conjecture on how much better/worse a race chassis would've been? I'm assuming they had a helmet on...

The race chassis adds the tube at the top of the halo, so there's 33-50% more structure right there - depending on how you feel about that 1" square tube on the floor. It's also not bent. The Race adds welded steel floors instead of the riveted aluminum ones.

But this isn't a racetrack style hit. This is the sort of thing that you get in a rally or hillclimb accident where there are inconvenient trees. I've seen a Miata that took the same sort of impact on a pole and it also had significant side intrusion. This is just a sucky way to crash a car, all that force concentrated on the area of the car with the least crumple zone.

In reply to Keith Tanner:

Yeah. As the rule stated a normal "door with side impact beam would suffice" wouldn't have done any better in that situation.

It would have made people "feel" better about looking at it because you won't see the seat, but the driver wouldn't have came out any better off.

An impact like that could have been even uglier in an Arial Atom, where the driver's hips/legs would only have been shielded from the tree roots by a thin tub of plastic:

Photos to not do justice to how flimsy that plastic seat is. We actually had an Atom perform a similar maneuver locally, I don't have pictures but the passenger was pretty banged up.

Sliding sideways into a tree is a bad plan. Don't do it.

Schrödinger's Flight Service wrote: In reply to Keith Tanner: Yeah. As the rule stated a normal "door with side impact beam would suffice" wouldn't have done any better in that situation. It would have made people "feel" better about looking at it because you won't see the seat, but the driver wouldn't have came out any better off.

A normal car has a rocker that's a good deal more structure than a 1" square tube.

The rule is "Cars must have at least 2 sections of side protection. Roll cages must have at least one bar in the door area. Stock door beam found in most cars is acceptable as a section, as is a substantial outboard frame rail or rocker panel."