F18 Sonic Boom

Pressure Trace
- Recorded by a SABER II Boom Event Recorder, located at approximately Lat 34.9497 N Long 117.8874 W
- Sample rate 10,000 Hz
- Signal low-pass filtered by a 3-pole Butterworth low-pass filter set at 2,258 Hz
- Aircraft travelling at M = 1.33 and 30,000 ft altitude
- 1.5 psf = 70 Pa
Simulations of boom using PCBoom3d
- Available weather balloon data from 16:29 GMT were used. Boom occurred at 21:07 GMT.
- Overlay of prediction on observed boom.
Map of aircraft trajectory, locations where boom was launched, wavefronts at arrival, and pressure contours.
- No boom is predicted in Lancaster or Palmdale, where it was heard at locations + and x.
- Low values of pressure bunch up to the north, but not the south.
Seismic Record
- Obtained from Tri-Net seismograph EDW TRI at Edwards AFB, located at Lat 34.88303N, Long 117.99106W
- Sampling rate 100 Hz.
- Instrument signal deconvolved to displacement, with passband 0.3 - 40 Hz.
- The record shows that the N-wave pushes the earth down about 0.4 microns and then pulls it up by about the same amount (U).
Record of seismically measured velocities
- They show a second boom which looks something like a U-wave, i.e., a focused wave.
Some pictures taken during the September 22nd meeting.

Last modified: Tue Oct 6 17:19:14 PDT 1998