Acceleration does play a part in qualifying a new Land Speed Record.  So does deceleration.  The measured mile being located in the middle of a twelve mile course, allows a distance for acceleration xACC of only 5.5 miles (29,040 ft). This graph shows that as speed records increase, the minimum acceleration aMIN must increase according as the square of speed record vREC.  The expression aMIN = vREC² / 2 xACC comprises the solutions for the puzzle.

 According to the specifications, Bloodhound LSR is capable of 2 g in acceleration and 3 g in deceleration.  The graph above calls for 1.15 g in constant acceleration to reach 1,000 mph over a distance of 5.5 miles.  As shown in the diagram below, aerodynamic drag increases with speed in a complicated way and makes constant acceleration difficult to achieve, especially above transonic speeds Mach 0.8.

Among the many technical challenges faced by Bloodhound LSR is the requisite turn-back maneuver between the outbound run and the inbound run.  During the acceleration phase of each run and upon reaching the start of the measured mile, Bloodhound LSR will be traveling at or above 1,000 mph. Approximately 3.6 seconds later the deceleration sequence begins...

[a] The jet engine returns to idle and its afterburner extinguishes.
[b] The rocket cluster shuts down.
[c] The airbrakes fold out into the airstream.
[d] The two drag chutes deploy.
[e] The wheel brakes gradually become effective. 

Of course, none of these actions will take place instantaneously.  Each passing second of delay can result in hundreds of feet of overshoot.  As a straight-line racing vehicle, Bloodhound LSR is limited to only five degrees of front-wheel steering left or right.  The conventional procedure for the turn-back calls for dispatching a truck that is trailoring a ramped dolly to meet the stopped racer, then to load and haul it to the remote facility for refueling and servicing.

Home Page

Puzzle Page

Math and Models