Rocket riddle

[A. Chesnick]

Hello All,
  Being that I am a total pack rat and never throw out any old magazines...
I was rereading a few and found these letters in the "New Scientist" of 1994
that still may be of interest to those followers of the V-2 sound and time
inversions of Gravity's Rainbow.

Regards Scott


Rocket riddle
                                           25 Jun 94


      Few in London had an inkling as to how good our defenses against
      V-1s were ('The V-1 menace: secret weapons that saved Britain', 4
      June). I was in London during the war and a V-1 landed in a road 60
      yards from our shelter, leaving a crater, 30 feet wide and 15 feet
      deep. The houses around were just piles of rubble.

      One day a V-2 landed 300 yards away. After the bang there was a
      loud rushing sound for several seconds. The Imperial War Museum
      says the rocket may have broken up on descending, the after sound
      being the casing coming down. Do any New Scientist readers know if
      you can hear a supersonic missile arriving, after it has arrived? I have
      puzzled over this for 50 years.

      Ernest Spratt Hayling Island, Hampshire

      ERNEST SPRATT
        From New Scientist magazine, vol 142 issue 1931, 25/06/1994, page 52

Hearing backwards
                                           16 Jul 94


      I, too, recall hearing this sound when a child and I remember the same
      explanation being proffered afterwards. Though this seems plausible, I
      now believe that there might be another, probably concurrent,
      mechanism.

      In the course of experimental work, I frequently detonate charges of
      high explosive weighing tens or a few hundred grams on, or directly
      above, steel plates lying on the ground. If no solid debris is likely to
      be projected, I usually observe the events from a distance of 20 or 30
      metres, protecting my ears with my hands.

      As soon as I see the flash, hear the (attenuated) bang and feel the
      blast, I remove my hands. Quite frequently (one in every hundred
      shots, perhaps) I hear a sound varying from a metallic ringing to a
      whine or even an apparently disembodied and rather eerie howl which
      sometimes lasts for several seconds.

      On such occasions I have frequently seen a smoke ring rising steadily
      from the cloud of smoke still at ground level. Such a vortex, which
      sometimes remains visible for tens of seconds, I suspect to be the
      generator of the sound. The most favourable condition for the
      generation of such vortices seems to be the detonation of an
      explosive charge in an open-ended, upright pipe.

      The characteristically deep conical crater of the fast V-2, as
      described by Spratt, perhaps similarly favoured vortex formation. A
      smoke ring is also frequently to be seen issuing from the muzzle of a
      large gun.

      The energy contained in vigorous vortices is, I believe, considerable,
      and, if not disturbed, may be retained for a surprisingly long time. On
      one memorable occasion a couple of years ago, wishing to be rid of
      some hundreds of kilograms of explosive, some old fuel oil and an old
      motor car at the same time, I retired to a promontory about a mile
      away.

      A splendid flash was followed by a generous bang. Though too far
      away to hear any howl, I saw an enormous smoke ring rise to a few
      hundred feet and drift slowly over my head where it became wobbly
      and dispersed some four minutes later!

      Sidney Alford Corsham, Wiltshire

      SIDNEY ALFORD
        From New Scientist magazine, vol 143 issue 1934, 16/07/1994, page 48
Hearing backwards
                                           16 Jul 94


      Yes, you could hear a V-2 coming after it had arrived (Letters, 25
      June). It was my good fortune, both from the points of view of my
      own personal safety and Ernest Spratt's curiosity, to be standing
      some distance from, and perpendicular to, the flight path of a V-2.

      It announced its arrival with its customary signature of a double bang
      (bow wave followed by explosion) followed by a sound as of
      something shooting away on a parabolic trajectory from the point of
      impact. This could have only been the sound of the final stages of its
      journey to us, in reverse.

      Instead of the usual double bang we had BANG, BANG, WHOOSH all in
      very quick succession.

      Ken Harrow West Wickham, Kent

      KEN HARROW
        From New Scientist magazine, vol 143 issue 1934, 16/07/1994, page 48