Buzzer wrote:

On Fri, 08 Aug 2003 21:09:57 GMT, Guy Alcala
wrote:

"The Air Force also conducted a quick look evaluation of a potential APR-26
replacement in April [1966]. An HRB-Singer 934-1B missile warning receiver
was installed in 62-4416 and test flown at the Sanders facility, which had a
Fan Song missile guidance simulator not available at Eglin.

And there we were in June 1966 sitting on the ground at Eglin with the
F-4C WWIV waiting for range time on the SADS and cancelling for rain
when another site was available. Here I thought and was led to believe
the Eglin SADS was the only one available..

The 934-1B
differed from the APR-26 in that it analyzed the modulation characteristics of
the C-band [i.e. radar L-band] guidance signal to differentiate between SA-2
missile activity and missile launch modes, while the APR-26 simply looked for
an abrupt amplitude increase. The HRB-Singer set performed well, but the Air
Force was already committed to a large APR-26 procurement and saw no
compelling reason to buy another system to perform the same function.

Shame they didn't have to stand up before a couple hundred pilots and
say we see no compelling reason to give you a better system that would
give you more confidence and might save your life! Welcome to the
realities of the Vietnam War..

At the time I'm sure the APR-26 seemed adequate, and they didn't realize its
shortcomings. If the APR-26 was already in low-rate production, it was probably
figured that getting something into action soonest was better than waiting for
something potentially better later. Jenkins describes a whole bunch of concurrent
programs and fits which they were experimenting with, and just getting some F-105F
Weasels completed and functional so they could test them was very difficult. There
were a lot of systems that were better on paper, but which proved difficult if not
impossible to make work in the time required. He also covers the APS-107 which was
rejected for the Wild Weasel II (F-100F) program and later considered as a
potential system (APS-107B internal for the F-105D along with the navy's ALQ-51
jammer (which later were installed in RF-101s), as well as the Bendix DPN-61
DF/homing system (the Az-el antennas) and various competing systems.

Only
after the Wild Weasel III F-105s were in combat was it learned that the
APR-26's design was based on possibly faulty intelligence regarding the
amplitude increase. This led to numerous incidents of flase lower
threat-level 'activity' indications when 'missile launch' should have been
displayed. The APR-26 was later modified to analyze the guidance signal and
the improved sets redesignated APR-37."

The original story I heard in June 1966 at the APR-25/26 class at
Keesler and later from the tech reps was the missile guidance signal
was feed into a dummy load. That caused the Activity Light to come on.
Then when they launched and switched to active guidance at a higher
power the Launch Light came on. Another variation on that was they
interrogated the missiles at low power before launch that gave the
Activity and then went high power to guide giving Launch light.

The latter would seem to make more sense assuming that the VPADF were really
'playing the L-band' to make us think they'd launched when they hadn't. I wonder
if our receivers would be sensitive enough to detect a dummy load at the time --
after all, the whole point was to warm everything up without warning everyone in
the area that they were ready to go (like a radar in standby).


No
mention at all of how the missile was quided until I took the
APR-36/37 factory course in 1968 at ATI/ITEK in Palo Alto, CA. Here
they went into the guidance pulse train and what the APR-37 looked at.
They talked like this was recent intel and here the info had been
around for years.

snip

It may well have been recent. They only got the missile prox. fuse and some
guidance data in Feb. 1966, from a Firebee drone that they flew around trolling for
SAMs, relaying the data to an RB-47 just before the drone was destroyed. And then
we got our hands on complete SA-2 systems after the Six Day War.

Guy