Re: [Phys-l] Robbie Maddison's Motorcycle jump

["Matt Coia" <matt.coia@gmail.com>]

Using the brakes and engine to change the speed of the wheels is a common
(and quite necessary) practice in any motorsport where jumping occurs.  It's
not only motorcycles but also 4 wheeled atv's and even snowmobiles that use
this to their advantage when off the ground.  I sometimes race
radio-contolled vehicles (1/10th or 1/8th scale) on off-road tracks with
jumps and the same is true.  Using the throttle to raise the nose or brakes
to drop the nose is needed to maintain control on landings, set-up for the
next jump, etc.  With r/c vehicles, it is common for over-zealous drivers to
completely flip their vehicles due to the rotational force generated.

Matt


On 1/3/08, David Abineri <dabineri@fuse.net> wrote:
> I have always supposed that a motorcycle jumper (ie Evil Knievel) has to
> worry about the orientation of the motor cycle during the flight so that
> the landing is made on both wheels when possible.
>
> Not having observed much in the way of aerodynamic surfaces on these
> motorcycles I am lead to believe that perhaps the rider uses
> conservation of angular momentum in order to orient the cycle in
> midair.  For example, putting the brakes on during the flight should
> bring the front wheel down.
>
> In observing Maddison's new world record of about 320 feet in the air on
> new year's eve, it was certainly clear that at one point in the flight
> the front wheel does in fact suddenly move downward in what seems to be
> a controlled manner.
>
> Does anyone know if such jumpers are in fact using conservation of
> angular momentum or some other method to keep the orientation safe for
> landing?
>
> Thanks for any insights.    David Abineri
>
>
>
> --
> D. Abineri     dabineri@fuse.net
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l