[ChrisB]

I remember reading some time ago in SELOC that one should not use the windshield frame as an aid in getting in and out of the Elise because it is made from GRP with no metal reinforcement. Some had experienced cracked windshield glass as a result of doing so. I believed what they said, but a recent experience demonstrated to me the extent of the situation.

At the recent SoCal Temecula outing, Shinoo (who is not a big burly guy) used the windshield frame as an assist getting into the Euro 111 there. I was amazed at the amount of deflection of the entire windshield that resulted from that. When I mentioned that to Shinoo, he reached up from his position in the driver's seat and fairly gently pulled on the upper windshield frame. The amount of movement was more than a little disconcerting.

Several people on this forum have expressed concern about chassis rigidity in an open top car and, wrongly, assumed the hardtop would add significant rigidity. I'm now left wondering if it might not be a good idea to have the top (either top) in place during very high-speed runs to counteract the wind force. I've never heard of a windshield failure at high speed, but then again, most Elise won't go as fast as the 111R and Fed, And, probably very few people in Sport 160s or Sport 190s were on a track at that speed without a top.

Any comment from Europe? Arno?

 

[Derek]

I can't imagine that Lotus would be stupid enough to design a car that’s windshield would fail when the car traveled at speed (even flat out at top speed)

Are you sure you didn't mean to post this question Here

 

[mikester]

Hi Chris -

As a former stress engineer in aerospace, I can assure you that's not an issue. The load that Shinoo put on the windshield in pulling/pushing is probably substantially more than just about any wind load (at least, in the direction he was applying that load), because the windshield is "raked" and not flat to the wind. Also, a little flex is not a big deal in terms of strength. Think about a large aircraft wings during an abrubt maneuver or turbulence. They're absolutely designed to flex, but that doesn't mean they're any where near a failure mode. So, no worries there !

Cheers, Mike G.

 

[rtking]

But ChrisB does bring-up an excellent point: One should never use the windscreen as a "handle" to lift yourself out of the car. (I saw the panic-stricken faces of everyone on the Temecula Tour as I reached up to the windscreen's header for support to get out of the car. )

I suppose that makes the vehicle even more "personal" in terms of who does and does-not drive it. Instructions will need to be remarkably clear to passengers to not use the windscreen for support.

Bob

 

[mikester]

Indeed. I'm going to be so incredibly paranoid with this car, it'll be pathetic ! :huh:

I'll be pestering everyone - don't slam the door! Don't scuff the sills ! Careful how you get in and out !

 

[ex-M3]

Hi Chris -

Think about a large aircraft wings during an abrubt maneuver or turbulence. They're absolutely designed to flex, but that doesn't mean they're any where near a failure mode. So, no worries there !

Cheers, Mike G.

IIRC the 777 wing was flexed over 20 ft until failure. I've seen the video and when it fails it sounds like a big freakin' gun going off.

 

[mikester]

IIRC the 777 wing was flexed over 20 ft until failure. I've seen the video and when it fails it sounds like a big freakin' gun going off.

Yeah I think you're right. Similar for the DC-10, and probably the other jumbo jets etc. Those test videos are pretty impressive ! It takes a tremendous amount of load to make an airliner's wing fail.

 

[ChrisB]

IIRC the 777 wing was flexed over 20 ft until failure. I've seen the video and when it fails it sounds like a big freakin' gun going off.

If you want to see wings flex, check out the B-52. On the ground they need wingtip wheels to support them. Watching them go down the runway (a very looong runway), the wings take off first, going from a very droopy curve to straight before the fuselage begins to lift off. At speed, when climbing and low on fuel, they flex upward about as much as they droop when parked.

By the way, in my question about windshield failure, I wasn't imagining the windshield frame breaking off and flying away, but whether it might flex enough to cause the glass to crack, as has apparently happened by people using it as a support.

A 150 mph wind is quite forceful...that's F2 tornado force. However, it wasn't clear to me how much of that actually hits the windshield versus being deflected upwards by the front clam surfaces.

 

[MOKOSpeeD]

To avoid damaging your windshield and for easy entry and exit from the Elise while in the garage, hang two trapezes from your ceiling. When you need to ingress, take a few steps and leap onto the trapezes allowing your body to slide naturally into the seats. When egressing, simply reach up for the trapeze and use inertia from your legs to swing backwards, away from the vehicle. Ta da! :clap:

Caution: Acrobatic abilities may be required. Moko corporation will not be responsible for any injuries associated with trapezes

 

[smoseley]

IIRC the 777 wing was flexed over 20 ft until failure. I've seen the video and when it fails it sounds like a big freakin' gun going off.

777 wings aren't made of glass

 

[smoseley]

Several people on this forum have expressed concern about chassis rigidity in an open top car and, wrongly, assumed the hardtop would add significant rigidity.

I assure you that having the hard top in place will make the windshield stiffer if someone tries to use it as a handrail.

 

[Randy Chase]

I can assure you that having the hardtop in place will make it more unlikely they would use the windshield as a handrail.