The tub-within-a-tub

[Franklin]

There could be some further gains in safety possible by putting the existing tub of an F1/CART/IRL car inside an outer larger tub and filling the space between them with a crushable energy absorbing material such as aluminum honeycomb. This would allow the inner tub an extra interval of deceleration when the outer tub has stopped moving due to contact with a fixed object such as a wall.

[cmd]

Franklin,

Today's "tubs" are of a carbon skinned honeycomb construction.

An outer skin and an inner skin of carbon fiber (sometimes uni-directional, and sometimes directional) with a aluminum core.

What you are suggesting is not a reasonable alternative.

What could be done is to increase the core thickness of the aluminum core, but that is usually sized for the section properties desired at that point and for any penetration (using ballistic Kevlar core)protection desired, like in side pods and around the cockpit.

[Peter Mallett]

Anybody remember the Lotus 81 (I think) which Chapman designed to circumvent the ground effect rules. It had a twin chassis. I wonder if he'd have got it approved by the FIA if he'd used the safety argument.

IMHO. If you put a tub within a tub, yopu would be increasing the impact problems with the inertia effect. I am willing to be corrected on this though.

You do have a fertile mind Franklin. Keep it up.

[Franklin]

It's pretty straightforward physics. You're taking advantage of crush space. (And I'm not talking about a chassis within a chassis like Chapman, I'm talking about a tub within a tub the same way IKB built the Great Eastern with a hull within a hull in 1859.)

Outer tub hits the wall. The wall is an immovable object so the outer tub stops moving. The momentum of the inner tub keeps it moving. Since the space between the inner tub and outer tub is filled with a crushable material (such as aluminum honeycomb) that crushable material decelerates the inner tub until it runs out of room and contacts the outer tub.

Since it is the material between the tubs that you're crushing NOT THE WALLS OF THE TUBS, it is immaterial that the walls of each tub are themselves sandwich composites with NOMEX honeycomb as their core material.

[enzo]

What Frankie suggest here is entirely feasable, except that not all areas of the inner tub will be subject to the same inertial loading, with the result being that you cannot design a system tat will work well in all situations ( angle of impact). However, a much more economical way to accomplish the same thing is already being done/experimented with : increase the space around the driver & fill that space with energy absorbing material pre-selected for its crush characteristics for the particular area of the body in contact with it.