If you try to design a road vehicle with efficient streamlining you soon realise that if the front of the 'tear drop' is going to be of a practical size the entire vehicle is a long as a bus.

The idea is to make the rear part of the vehicle a simple inflatable bag that is only deployed above a minimum speed. At lower speeds the bag is reeled in and stowed returning the vehicle to the length we are all accustomed to.

Note that the tail is not inflated by movement of vehicle as that would just be added and continued drag. A small compressor is required to inflate it and some sort of winding up mechanism is required to retract the tail.

The advantages are very low weight, no significant stability issues **, cheap and at least the illusion of some sort of padding between you and the idiot tailgater.

** Long tailed race cars have been tried at various times but once the tail is long enough to be effective it becomes susceptible to cross winds. The inflatable tail would just be blown aside.
-- KiwiJohn, Jan 06 2004

"Note that the tail is not inflated by movement of vehicle as that would just be added and continued drag. A small compressor is required to inflate it..."
You could have an aperature let moving air fill the form. Once the form is filled, close the aperature. This saves the weight of the compressor.
-- phoenix, Jan 06 2004


For some reason I thought this had something to do with Cher Impersonators
-- duroncrush, Jan 06 2004


it doesn't?
-- dickity, Jan 06 2004


not retracting tails for all, either?
-- po, Jan 06 2004


Dag, stiff or not it could actually be attached via a properly faired hinge and it would still do its purpose.
-- KiwiJohn, Jan 07 2004


I'll take mine in Stegosaurous!
-- Letsbuildafort, Jan 07 2004


Can I still bolt a spoiler to it?
-- dobtabulous, Jan 07 2004


I believe this has been tried on tractor-trailers. While it worked well in reducing drag, it was found to be cumbersome and not worth the trouble.
-- Freefall, Jan 07 2004


The practicality of it primarily rests in your ability to make it automated and automatically deployed. Systems used in trucks required the user to take them off and put them on during loading and unloading operations, and that's a pain.
-- kevinthenerd, May 31 2006



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