Frontal Protection in a '40

[Tom Hudson]

91740GT :
"Three years ago at Oulton Park i was out in practice session on a wet track for one of the SR&GT races. 6th lap and i merrily go powering up the Clay Hill section and at the "crest" the front lifts up and i,m airborne and steeringless ( wheels were estimated to be a foot or more of the track ).Round we go and hit the armco at around 80 mph taking the front off and then spinning, hitting the rear end into the armco and coming to a halt 100 yards down the track."

This is a very worrying incident for me as my replica 40 nears completion and,at long last,track days become a reality. Can a 40 really generate enough lift to raise the front off the ground, in the wet, at a relatively gentle crest such as Clay Hill?

Perhaps Graham would be good enough to give us more info. and hopefully put my mind at ease.

Regards

Tom

[Jim c]

Keith

In reference to the pole damage.
In OZ all our poles outside our pubs are extra extra heavy duty.

Jim

[Keith Hardy]

That figures if that was a typical closing time incident!

[David Morton]

Closing time? Does that exist there?

[Lynn]

Graham,

I'm with Tom, more info please sir? What chassis was this.


Tom,

While the 40 does lighten up at speed:

Lift/Drag for the MK II
100 lbs. @ 150 mph, with 525 lbs. of drag
144 lbs. @ 180 mph, with 756 lbs. of drag
177 lbs. @ 200 mph, with 933 lbs. of drag

And I have heard numbers like 10% of the cars weight

Unless you are up well over ≈ 170 in a plane MK I replicar, you are not going to start flying; even then I think the issue is more one of degredation of handling than reaching Vr (airplane speak for speed for rotation.) Now it sounds like you are more familiar with this particular crest than I am, but GT40s will obey the laws of physics and if conditions are just right and the upward vector of inertia is large enough and some outside force (aerodynamics) doesn't intervene, up she gos. With a wet track and a corner to deal with, it doesn't take much loss of directional control to get in very bad shape.

Lynn

[91740Gt]

Tom and Lynn.

You must understand that this was not a track day accident but a pre race practice session. I had already completed five laps to bed 40 down and find its feet in very wet and slippery conditions and i decided to go for a better grid position from then on. I was flooring it in third up that slope and as i came over the top of what is a gentle crest the nose lifted. The marshals stated that the front wheels lifted at least a foot of the deck and that was it.

This is a notorious part of the track and the great and the good regularly fall foul of this section. Almost certainly i had the car set too soft for the wet conditions and probably suffered from rear end squat setting in at full acceleration. One should never underestimate the amount of rear end downforce that the 40 generates and i do sometimes worry about the extra spoilers that some builders are putting on their road cars to replicate race vehicles without thinking of the potential problems in the right/wrong circumstances.

I only mentioned this racing accident because Keith was asking about protection in a 40.

Regards,

Graham @ GTA.

[Pete.]

Originally Posted by David Morton

Closing time? Does that exist there?

Closing time over here is when the bouncer chucks you out, or you fall over. Whichever comes first.

[Keith Hardy]

Originally Posted by 91740Gt

I only mentioned this racing accident because Keith was asking about protection in a 40.

Regards,

Graham @ GTA.

And in that regard, answered my question very well with your experience. The '40's seems tougher than they look for sure....at least the originals did, I have no experience of replicas at all.

What was that prolific '40 racer's name, Ron Fry? I know he had some quite lurid moments in his '40 - I saw one in the '70's which would have totalled a lesser car, at Brands I think, but it was up again racing within a couple of weeks.

He was quite a boy, probably the hardest '40 racer ever.