Vietnam era F-4s Q

Tex Houston wrote:

"Guy Alcala" wrote in message
. ..
This was separate from the QRC-317 SEE-SAMS/QRC-317A ALR-31, which was
eventually incorporated into the APR-25 ('SPOT SAM') and turned it into
the
APR-36 (the 'centered in both beams' A/S light). Jenkins, further on his
his
section on the Weasels, also seems to mention the same mod you call the
'Bowman', although not by name. The description certainly fits:
Guy


I suspect it is not "Bowman" but "Bauman" as this sounds very much like the
project he invented at Takhli about 1966-1967.

So it seems, given the link Bob found.

Guy

Guy Alcala wrote:

Ed Rasimus wrote:

Guy Alcala wrote:

"The Air Force also conducted a quick look evaluation of a potential APR-26
replacement in April [1966].

Not to disparage Jenkins, who's done great research on the F-105, but
"potential replacement in April (1966)" doesn't track well with my
experience. I arrived at Korat in May of '66 and at that time the
APR-25/26 was just being initially installed in the operational jets.

As noted below, this was the WWIII fit, and they were just starting procurement.

OK, WW III was the F-105F. And the elaboration that it was
pre-deployment of the system helps, but it still doesn't make sense to
be seeking a replacement before you've operationally employed the
already purchased equipment. Things were happening fast in EW at that
time, so maybe that's the excuse.


I'm not a "squeaks and beeps" EW, but here's what I was taught about
the sequence for the SA-2. The initial TDU (Threat Display Unit) light
were for "Lo" indicating a low PRF (pulse recurrence frequency), as
you got lit up with both beams of the Fan Song (Az & El), you got a
"Hi" for high PRF.

H'mm that seems a bit off. Normally, fire control sets search at a lower PRF, then
track at a higher one.

So, Low PRF would indicate general search mode, High PRF would indicate tracking
_somebody_ (at shorter range). That at least would be the case with the APR-25.

About ten minutes after that post above, an aging synapse fired and I
recalled that 25/26 didn't really deal with Azimuth/Sector, but the Lo
PRF was search and the Hi PRF was switching to track mode.

So, prior to the ALR-31/APR-36, you might be in one or both beams and getting High
PRF, but not be in the center of the Fan Song sweep because it was actually
targeting some other a/c close to the same angle between the radar and you, leading
to unnecessary maneuvers and high pulse rates. You'd also pick up the L-band
guidance signal, again without necessarily being the target.

When missile data upload was taking place, another
frequency was employed (that's where an EW could tell you more) you
got an "Activity" light and when command guidance signals were
received, indicating control signals to the missile airborne, you got
the "Launch" light.

Right, the guidance used the C-band dish on the left of this picture (the E/F or
G-band tracking antennas are the horizontal and vertical troughs):

http://fas.org/nuke/guide/russia/airdef/fan_song2.jpg

Here's what I'm talking about (again from the Air & Space article
Bob pointed out):

"As tactics were developed in the air, field modifications to the Wild Weasel
systems continued on the ground. A key weakness of the equipment was that if
several SAM sites were displayed on the scope and the light that signaled a launch
was illuminated, there was no way to know which site had fired and from which
direction the SAM was coming. "I heard the crews complaining about that," says
Weldon Bauman, who in 1967 was a junior enlisted technician at Takhli. "---details snipped---

No ****! You bet we were complaining. It was a "good news/bad news"
kind of thing. We were glad the RHAW gave us info, but really wanted
more detail. Discrimination between radars in the saturated
environment of Pack VI was important and knowing where to look in a
split-second to acquire the missile visually was critical to survival.

Thanks. BTW, in the case of say a two-ringer growing to a three, did the strobe
extend in from the periphery, or out from the center? I've always assumed it was
the latter (looking similar to a PPI display), but I've never seen a source I trust
which says which it was.

You are correct. The "origin" of all strobes was the center of the
scope. The strobe extended outward in the direction indicated by the
integration of signal strength from the several antennae on the
aircraft skin. Lot of folks never really broke the code that the
length of strobe (1-ring, 3-ring, etc.) was signal strength not
proximity to the emitter. There was some correlation, but technically
it was strength not range.

In less saturated areas, we could often work a single Fan Song and get
station-passage, just like flying over a VOR. On the nose, on the
nose, then swing to the tail. Good way to find a likely spot to leave
some CBU.


Ed Rasimus
Fighter Pilot (ret)
***"When Thunder Rolled:
*** An F-105 Pilot Over N. Vietnam"
*** from Smithsonian Books
ISBN: 1588341038

Guy Alcala wrote:

--snipped---


Guy,

Since I know you love all the techno details, have you gotten Anthony
Thornborough's book, "Iron Hand: Smashing the Enemy's Air Defenses"?

Great source with incredible detail. Better than Jenkins and
head/shoulders above Larry Davis' Squadron Signals soft-cover
mini-book, "Wiild Weasel".


Ed Rasimus
Fighter Pilot (ret)
***"When Thunder Rolled:
*** An F-105 Pilot Over N. Vietnam"
*** from Smithsonian Books
ISBN: 1588341038

On Sat, 09 Aug 2003 06:05:51 GMT, Guy Alcala
wrote:

As noted below, this was the WWIII fit, and they were just starting procurement.
The question was whether they'd confirm
procurement of the APR-26 or go with the HRB-Singer set. Almost no sets of either
type had yet been fitted to trials a/c, and only a few of the APR-25/-26/IR-133 to
the F-100F WWs.

HRB-Singer set test Apr 66
F-105 weasel test flying Jan 66 Deployed May-Jun 66
F-4 weasel flying sometime before June 66
Didn't find out APR-26 might be faulty until after Jun 66..

Ok. They took a chance with the APR-26 since it was flying and ended
up being wrong..

It might have also been a maintenance thing keeping the 26 over the
Singer. Simple transistors against (maybe) multi-layer ic type boards
that would require extensive tech rep or depot support.

H'mm that seems a bit off. Normally, fire control sets search at a lower PRF, then
track at a higher one. FWIW, the first available site I could find credits Fan
Song C/E with the following PRFs:

PRF 828-1440 Search. 1656-2880 Trk.

Makes me wonder now. Did they "flip a switch" and double the prf? Or
did the prf double because the aircraft was in the box and two beams
at the same prf were hitting?

"The Fan Song was one of the first electronic scanning radars--it directed its
energy without having to move its antenna. "The way the Soviets built the Fan Song

Tech school memory - Lewis scanner. English name for soviet radar
scanning? English name for U.S. developed radar technique in late
40's-50's. Not further developed by U.S. because it was inefficient
use of power.

Thanks. BTW, in the case of say a two-ringer growing to a three, did the strobe
extend in from the periphery, or out from the center? I've always assumed it was
the latter (looking similar to a PPI display), but I've never seen a source I trust
which says which it was.

Center going out as you got closer to source.If I remember right on
the APR-25 a really strong signal would cause the signal to go to the
outer edge of the scope and curl back in a loop. Lots of strong
signals - lots of loops..

Factory schools on equipment were interesting. Fresh off the drawing
boards and the solder still cooling.G
APR-36/37
Student - What does that circuit do?
Instructor - I don't know.
Student - What does the engineer that designed it say?
Instructor - He can't remember..

Buzzer wrote:

Center going out as you got closer to source.If I remember right on
the APR-25 a really strong signal would cause the signal to go to the
outer edge of the scope and curl back in a loop. Lots of strong
signals - lots of loops..

See my previous regarding proximity vs signal strength. Sure, as you
get closer, you get a stronger signal, but the parameter was strength.

No looping. The strobe went out to the limit of the display, that's
all.


Ed Rasimus
Fighter Pilot (ret)
***"When Thunder Rolled:
*** An F-105 Pilot Over N. Vietnam"
*** from Smithsonian Books
ISBN: 1588341038

On Sat, 09 Aug 2003 16:12:58 GMT, Ed Rasimus
wrote:

Buzzer wrote:

Center going out as you got closer to source.If I remember right on
the APR-25 a really strong signal would cause the signal to go to the
outer edge of the scope and curl back in a loop. Lots of strong
signals - lots of loops..

See my previous regarding proximity vs signal strength. Sure, as you
get closer, you get a stronger signal, but the parameter was strength.

Probably why I set the sensitivity of each freq band to x db that
would give y deflection. Instead of x number of yds from sam site
would give a certain deflection since not all sam sites put out the
same exact power?G

No looping. The strobe went out to the limit of the display, that's
all.

Must have looped on the bench due to the loopy technician.

Ed Rasimus wrote:

Guy Alcala wrote:

Ed Rasimus wrote:

Guy Alcala wrote:

"The Air Force also conducted a quick look evaluation of a potential APR-26
replacement in April [1966].

Not to disparage Jenkins, who's done great research on the F-105, but
"potential replacement in April (1966)" doesn't track well with my
experience. I arrived at Korat in May of '66 and at that time the
APR-25/26 was just being initially installed in the operational jets.

As noted below, this was the WWIII fit, and they were just starting procurement.

OK, WW III was the F-105F. And the elaboration that it was
pre-deployment of the system helps, but it still doesn't make sense to
be seeking a replacement before you've operationally employed the
already purchased equipment. Things were happening fast in EW at that
time, so maybe that's the excuse.

Yes, they had multiple systems in concurrent development, and were essentially trying everything.

snip

So, Low PRF would indicate general search mode, High PRF would indicate tracking
_somebody_ (at shorter range). That at least would be the case with the APR-25.

About ten minutes after that post above, an aging synapse fired and I
recalled that 25/26 didn't really deal with Azimuth/Sector, but the Lo
PRF was search and the Hi PRF was switching to track mode.

Yeah, I thought you might be conjoining APR-25/-26 with -36/-37.


So, prior to the ALR-31/APR-36, you might be in one or both beams and getting High
PRF, but not be in the center of the Fan Song sweep because it was actually
targeting some other a/c close to the same angle between the radar and you, leading
to unnecessary maneuvers and high pulse rates. You'd also pick up the L-band
guidance signal, again without necessarily being the target.

When missile data upload was taking place, another
frequency was employed (that's where an EW could tell you more) you
got an "Activity" light and when command guidance signals were
received, indicating control signals to the missile airborne, you got
the "Launch" light.

Right, the guidance used the C-band dish on the left of this picture (the E/F or
G-band tracking antennas are the horizontal and vertical troughs):

http://fas.org/nuke/guide/russia/airdef/fan_song2.jpg

Here's what I'm talking about (again from the Air & Space article
Bob pointed out):

"As tactics were developed in the air, field modifications to the Wild Weasel
systems continued on the ground. A key weakness of the equipment was that if
several SAM sites were displayed on the scope and the light that signaled a launch
was illuminated, there was no way to know which site had fired and from which
direction the SAM was coming. "I heard the crews complaining about that," says
Weldon Bauman, who in 1967 was a junior enlisted technician at Takhli. "---details snipped---

No ****! You bet we were complaining. It was a "good news/bad news"
kind of thing. We were glad the RHAW gave us info, but really wanted
more detail. Discrimination between radars in the saturated
environment of Pack VI was important and knowing where to look in a
split-second to acquire the missile visually was critical to survival.

One hopes they gave Bauman a DSM. Rare for enlisted, but not unknown. They gave one to Senior
Chief Radarman Nowell, the senior controller on U.S.S. Chicago in 1972 (aka "The Voice of Red
Crown"), for his controlling of 13 successful interceptions. Admittedly, he was only the second
navy enlisted man to be awarded one, but Bauman's work would seem to be as important. Googling I
see that he's an inductee of the Association of Old Crows Hall of Fame for "Missile
Warning/Launch Circuits."


Thanks. BTW, in the case of say a two-ringer growing to a three, did the strobe
extend in from the periphery, or out from the center? I've always assumed it was
the latter (looking similar to a PPI display), but I've never seen a source I trust
which says which it was.

You are correct. The "origin" of all strobes was the center of the
scope. The strobe extended outward in the direction indicated by the
integration of signal strength from the several antennae on the
aircraft skin. Lot of folks never really broke the code that the
length of strobe (1-ring, 3-ring, etc.) was signal strength not
proximity to the emitter. There was some correlation, but technically
it was strength not range.

Thanks. I knew that that generation of RWRs indicated signal stength rather than range. What was
the problem with crews not being able to grok it? I assume they were told what the strobe length
represented, so was it a cognitive problem in combat, i.e the brain is used to seeing a vector
length represent distance, so they automatically reverted to that under pressure?


In less saturated areas, we could often work a single Fan Song and get
station-passage, just like flying over a VOR. On the nose, on the
nose, then swing to the tail. Good way to find a likely spot to leave
some CBU.

Better you than me, although flying directly overhead is probably fairly safe as you'd be inside
SA-2 minimum range. It's a damned good thing that they didn't have any shorter-ranged SAMs
(co-located with the SA-2s), or I fear you would have only been able to do this once, if that ;-)

Guy

Ed Rasimus wrote:

Guy Alcala wrote:

--snipped---

Guy,

Since I know you love all the techno details, have you gotten Anthony
Thornborough's book, "Iron Hand: Smashing the Enemy's Air Defenses"?

Great source with incredible detail. Better than Jenkins and
head/shoulders above Larry Davis' Squadron Signals soft-cover
mini-book, "Wiild Weasel".

Been trying to find it through the library system, but no luck so far.
If that doesn't work, I'll just have to break down and buy it, but I try
to keep the size of my permanent library down to just the essential
references so I don't have to live outside. I'm a big Thornborough fan
anyway, although occasionally he gets some bad info. If he's more
detailed than Jenkins', who did the best job I've seen yet describing the
USAF Vietnam-era fighter RWR/ECM gear, it sounds like one of those must
haves.

Guy

Buzzer wrote:

On Sat, 09 Aug 2003 16:12:58 GMT, Ed Rasimus
wrote:

Buzzer wrote:

Center going out as you got closer to source.If I remember right on
the APR-25 a really strong signal would cause the signal to go to the
outer edge of the scope and curl back in a loop. Lots of strong
signals - lots of loops..

See my previous regarding proximity vs signal strength. Sure, as you
get closer, you get a stronger signal, but the parameter was strength.

Probably why I set the sensitivity of each freq band to x db that
would give y deflection. Instead of x number of yds from sam site
would give a certain deflection since not all sam sites put out the
same exact power?G

No looping. The strobe went out to the limit of the display, that's
all.

Must have looped on the bench due to the loopy technician.

I have a vague memory of seeing a photo or film of an APR-25 display
somewhere, which IIRR did loop. Maybe this was film of a bench test, and
you'd never get close enough to a site in flight for the signal strength to
be great enough for that to happen?

Guy

On Sat, 09 Aug 2003 07:06:15 GMT, Guy Alcala
wrote:


Are you registered here?
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EW 101 1/1999