Text 21923, 93 rader
Skriven 2012-03-02 20:44:58 av HAP NEWSOM (1:123/140)
     Kommentar till en text av GLEN JAMIESON
Ärende: SILENT SERVICE 20301
============================
Hey Glen!
-> 
->  ->  HN> That would have probably been the HorizonT a
->  ->  HN> swinglens all mechanical camera...basic but
->  -> 
->  -> I think so.  A simple design, but solid, and it worked well.  Our
->  -> camera was made of fibreglass, took 75 mm film, weighed 1/3 lb and
->  -> took high quality pictures (one at a loading) from an altitude of
100
->  -> feet, of everything from directly below, to above the horizon.  It 
was
->  -> carried in a nylon dart that was launched, almost silently, from a
->  -> foot-pumped compressed air gun.  My job was designing the gun, the
->  -> dart, timer and camera actuator.  Others did the camera, which was
->  -> designed to take launch and landing accelerations of 1000g.
->  ->
->  HN> The really critical elements would be the 
->  HN> film transport (to keep the film flat 
->  HN> on the film plane) and to keep the lens
->  HN> working properly. those would be the only
->  HN> moving parts to deal with once the body
->  HN> was sturdy enough to take the impact of 
->  HN> landing.
-> 
-> The camera was loaded in a light-proof box by feel.  A pre-cut film
-> 125mm x 75mm was slipped into the curved detachable back, which was
-> clipped onto the camera body, and the lens swung to the "ready"
-> position.  One of the most difficult problems was light-proofing the
-> fibreglass body.
-> 
Would be very interesting to see
photos of the contraption! And
it sounds like it was fun to use!!
 
->  -> When demonstrating it to the military, to show its easy portability, 
I
->  -> arrived at the test field on a bicycle, carrying the complete
->  -> equipment on the handlebars.
->  ->
->  HN> Sounds interesting too! I would have liked
->  HN> to have seen the launching system and 
->  HN> design for the "projectile"...would be
->  HN> fun to do even today!
-> 
-> My launcher used foot-pumped compressed air stored at 120 psi in a
-> spherical aluminium tank surrounding the quick-opening valve mechanism
-> which allowed the pressure to be instantly dumped under the nylon
-> dart, about 120mm diameter, which fired it out of the metre-long
-> nylon barrel.  As the propelling air was expanded almost down to
-> atmospheric pressure by the time the dart left the barrel, there was
-> practically no noise, which was one of the design requirements.
->
How long did it take for you to 
pump it up to 120psi? and how
much volume are we talking about
with the tank??
 
-> A portion of that high pressure air was stored in a space within the
-> dart, and slowly leaked out through an adjustable needle valve.  At a
-> pre-set pressure, the remaining air was dumped into an actuator which
-> released the camera "shutter".  This was usually set to occur just
-> before apogee, while the dart was still rising vertically.
->
Sounds quite complicated!!
 
-> To prevent the dart from rolling during its upward flight, I used a
-> vane with a tiny gyroscope, similar to that used by the US Sidewinder
-> missile. The gyro was spun up by a swinging weight during launch.
-> Amazingly, everything worked!  I thought that the quick-opening valve
-> in the launcher would have been patentable, but then, in my later
-> research, I found that a Russian had also invented one using the same
-> principle, for use in a Wilson cloud chamber.  Unfortunately he
-> published first. The only patentable device that came out of my design
-> was the high hysteresis shock absorber which protected the camera, etc
-> when the dart hit the ground at the end of its flight.  That was a
-> simple design using an "educated" piece of polythene tubing.
->
Very interesting...I'm 
surprised you did not use
some sort of accelerometer
and gyro combo!

-> After that, my next project was a super-efficient air-launched
-> submarine detection sonar buoy...  Nothing like variety!
-> 
Ok...now that's just WRONG!!!(grin)
BTW I have a new friend in Oz..she's
a medic on a collins class sub out of
Sydney!
chat with you soon!
ha
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