BigDog. – 11/06/2013 16:07 GMT
IIRC, car alarms have a ‘trembler’ switch that detects anyone tampering with the vehicle and set off the alarm. Concorde used reheat on takeoff (basically fuel was sprayed into the jet pipe and caused extra gas expansion and thus power), this also caused a ‘crackling’ type of sound which was the right frequency to cause the tremblers to tremble.
When she took off from LHR, you could hear car alarms triggered in the closest staff car parks.
That’s my opinion.