[Milsurplus] [Boatanchors] Hallicrafters and A-Bombs (Hello, NSA and HSA!)

[J. Forster]

> Possibly, though most of the weapon peripherals were developed by LASL for
> specific purposes because of the magnitude of the forces involved.

Well, the overpressures decay pretty rapidly away from ground zero. The
ART-4 was designed to measure thye pressure from an exploding AA shell,
several inches in diameter, a few tens of feet away.

> The
> canister instruments finally decided upon were specially designed and
> built condenser microphones.

So are te ART-4s. I can take pics if you like, and I have the book if you
want it.

> I'm not near my documents at the moment, but
> I think there was an air bleed to the microphone chamber that allowed the
> microphone to ignore slow changes in pressure, such as the altitude change
> during the drop, while maintaining calibrated accuracy for the over
> pressure pulse.

Of course.

-John

===============
>
>> On Mar 30, 2014, at 12:59 PM, "J. Forster" <jfor at quikus.com> wrote:
>>
>> I wonder if those pressure probes might have been ART-4 derived, because
>> that's exactly what the ART-4 does...  it monitors pressure pulses to
>> determine target scoring for gunnery practice.
>>
>> They transmit on 55.5 and 56.75 MHz.
>>
>> -John
>>
>> =============
>>
>>
>>
>>> Nope.  The radar altimeters were in the 400mHz range.
>>>
>>> Three AN/ARR-5 receivers were used in whatever Silverplate airplane was
>>> designated the instrumentation aircraft for each mission, with the task
>>> of
>>> dropping three parachuted pressure instruments to monitored the
>>> pressure
>>> wave created by the weapon.  With that data and knowing the altitudes
>>> and
>>> positions of the three canisters, it was possible to calculate the size
>>> of
>>> the over pressure pulse and thus the yield of the weapon.  The
>>> instrumentation aircraft preceded the weapon carrier, IIRC, to allow
>>> the
>>> canisters time to descend a bit from the high altitude the aircraft
>>> were
>>> flying. The canister frequencies were clustered around 50MHz or
>>> so...somewhere back home I have the specific freqs involved from a LASL
>>> report years after the fact.  So, the S-36 was probably in the rack to
>>> permit calibration of the pressure sensors for testing.
>>>
>>> 73,
>>> - Mike  KC4TOS
>>>
>>>
>>>
>>>> On Mar 30, 2014, at 11:01 AM, "David Stinson" <arc5 at ix.netcom.com>
>>>> wrote:
>>>>
>>>> I guess it would work better with the link:
>>>>
>>>> http://www.alternatewars.com/Bomb_Loading/Bomb_Guide.htm
>>>>
>>>> The receiver is an S-36, so likely to listen to the altimeter
>>>> transmittters.
>>>> _____________________________________________________________
>
>