Oooo, ya bugger! (Although I feel obliged to ask how bad the "going up" injury would have been without the helmet )In 20 years of competing in motorsport the worst injury I had was caused by a helmet! :-(
We hit a particularrly large yump on the Scottish International Rally and my helmet got jammed between the roll cage and the seat head rest, wrenching my neck as i came back down and my helmet/head didn't!
The Scottish International is quite a big one, isn't it. Most of my competing was only in Land Rovers (with 5.7l V8 engines but still Land Rovers) in safari events, but we wore lids all the time, even when practising on our own farm land.