metals "crumple" to absorb some of the shock of impact.
There are a few tricks that F1 have that are surprising in their effectiveness.
They fill voids with tiny balls around 2mm in diameter made of a material that when crushed turns to a fine dust. The drivers tub is made of carbon fiber and aluminium ( or a synthetic) honeycomb that prevents it shattering.
The weight of a F1 nose cone is unbelievable at around just 3kg.
Yet it can help de-accelerate the 750kgs mass of a F1 car so a driver can walk away from a head on 100mph impact.
These principles when applied at design stage would reduce typical heli de-accelarations could have a dramatic impact on survivability.
But my general contention is for the cell to be able to break and tumble away from the load bearing structure of the craft, leaving fuel tank and the heavy bits behind. Dodging the rotor blades is the tricky bit!
Mickjoebill