Text 22153, 179 rader
Skriven 2012-03-07 15:19:30 av HAP NEWSOM (1:123/140)
     Kommentar till en text av GLEN JAMIESON
Ärende: SILENT SERVICE 20306
============================
Ahoy Glen!
-> 
->  ->  -> 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.
->  ->  -> 
->  -> Picture a spherical aluminium pressure tank (using Imperial units,
->  -> which is what we had at that time, long ago) about 10" diameter,
with
->  -> a yard long, 4 1/2" diameter nylon tube (made by spirally wrapping
->  -> strips of nylon sheet around a former, glued with a resorcinol 
solvent
->  -> glue).  The base of the pressure tank sat in a base similar to that
->  -> used on modern computer monitors so that the launch angle could be
->  -> adjusted.  The foot operated air pump, also of aluminium, was hinged
->  -> to the base so it could be folded up for easy carrying.  The dart,
->  -> also made of nylon, comprised a cylinder into which the camera was
->  -> placed, above it a conical pressure tank charged by the launch air
->  -> through a rubber flap valve, and above that, the telescopic shock
->  -> absorber.  The launch trigger was a small button on the side of the
->  -> tank.  No electrical stuff anywhere in the system.
->  ->  
->  ->  ->  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!
->  -> 
->  -> The original idea came from an old man who made his own wooden 
camera,
->  -> stuck it on a wooden dart launched by big rubber bands, and took
->  -> aerial photos of his neighbours' back yards.  He used a string to 
spin
->  -> up his gyro stabiliser before launch.  We greatly refined the idea.
->  ->
->  HN> Hmmm was he looking for lady sunbathers??
-> 
-> That is what we always suspected.  He didn't admit to it, though.
->
Probably married! 
  
->  ->  -> My launcher used foot-pumped compressed air stored at 120 psi in 
a
->  ->  -> spherical aluminium tank surrounding the quick-opening valve 
->  HN> 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.
->  ->  ->
->  -> I think it was only about 2 minutes to pump up the tank.  Enough
->  -> volume to expand it almost down to atmospheric pressure by the time
->  -> the dart left the barrel.  Not much.  I was particularly proud of
the
->  -> very light quick-opening valve that dumped the whole of the 
compressed
->  -> air store into the space beneath the dart in about a millisecond.
->  ->
->  HN> Two minutes is not bad at all!
-> 
-> I had the choice of any lightweight energy source to propel the dart,
-> and after looking into the alternatives of springs, rubber bands and
-> blank .22 cartridges, decided on compressed air storage of the
-> operator's energy biscuits.
->
With that much weight, I'd have suspected
a much more powerful launching system.
You would want to get as much altitude 
as possible for two reasons 1) more 
photographic coverage and 2) better
chances of remaining undetected both
during flight and recovery.
  
->  ->  -> 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
->  ->  -> pre-set pressure, the remaining air was dumped into an actuator
->  ->  -> released the camera "shutter".  This was usually set to occur 
just
->  ->  -> before apogee, while the dart was still rising vertically.
->  ->  ->
->  ->  HN> 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
->  -> 
->  -> The engineers working on the project were both mechanical, so all
->  -> components were simple mechanical.  :) To measure launch and landing
->  -> accelerations I used bits of resin-cored solder of different
lengths,
->  -> which bent or didn't bend.
->  ->
->  HN> Now you could do it with miniature
->  HN> electronics and a small battery.
-> 
-> Very likely, except that if I was designing the modern equivalent to
-> do that same function it would be a tiny, battery-powered, remotely
-> controlled drone aircraft carrying a digital camera.
->
As would I but it'd have to be a very
small to remain undetected..I know that
they have remote controlled blimps with
digital cameras attached. I have seen
them in use at the ballpark!!
 
->  ->  -> After that, my next project was a super-efficient air-launched
->  ->  -> submarine detection sonar buoy...  Nothing like variety!
->  ->  -> 
->  ->  HN> Ok...now that's just WRONG!!!(grin)
->  -> 
->  -> That entailed going down in a one-man capsule towed by a work boat,
->  -> with its depth controlled by paravanes worked by 2 handwheels
inside.
->  -> Once I got the hang of it, control was easy, and I could skate
along,
->  -> just clear of the seabed, banking to one side or another.
->  -> After work the boat master/owner sometimes dived down and caught
->  -> scallops for us to eat.  They were delicious, with a little white
->  -> wine, which I often happened to have with me.
->  ->
->  HN> Now why am I not surprised at that?
->  HN> (grin)...I like scallops!
-> 
-> So do I.  My favourite shellfish.
->
One of my favorites!
  
->  -> And so the defence of Australia was kept in good hands.
->  -> 
->  ->  HN> BTW I have a new friend in Oz..she's
->  ->  HN> a medic on a collins class sub out of HN> Sydney!
->  -> 
->  -> I sympathise with her.  Those subs have been notorious for faults.
->  ->
->  HN> Boy are they ever! 
-> 
-> And now they are talking about replacements.  Suggestions that we
-> should buy US, Brit or French nuclear subs have been countered by
-> comments that they are all too big, and can't operate in shallow,
-> littoral waters.  Only smaller, non-nuclear submarines can go there.
-> Modern conventional craft built with air-independent propulsion and
-> lightweight lithium-ion batteries can operate for weeks without
-> surfacing.
-> 
There is a lot of discussion in the 
Submarine community on just that 
subject. There is a powerful lobby
in Aus that wants to build them
domestically and an equally vocal 
side that points out how poorly 
that plan worked when it was last
tried (Collins Class). There are 
classes of smaller nuke boats that
would be capable of working "inshore"
just as well as "blue water". Many of
the US boats spent more time in
"shallow" ops than in deep ops! 
However if it were ME making the
purchase...I'd be looking at the
Swedish boats..specifically the
Gotland class boats, with air
independent propulsion. There's
not much of a need for huge 
range and those dang boats are
very VERY quiet!
chat with you soon!
ha
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