Vietnam era F-4s Q

Buzzer wrote:

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

Are you registered here?
http://www.jedonline.com/default.asp
Quick Search apr-25
At the bottom of results
EW 101 1/1999

Apparently I haven't been there in quite awhile, as they
wouldn't accept my login and I had to register again.
Thanks for the cite.

Guy

Buzzer wrote:

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

snip

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?

snip

I imagine PRF changed automatically as soon as they started auto-tracking. Otherwise,
they could do so manually when jamming required manual track. The Fansong actually had
three guys to do manual tracking, one each for range, altitude and azimuth.

Guy

Juvat wrote in message . ..
After an exhausting session with Victoria's Secret Police, Ivan
blurted out:

:-)

You're welcome!

Many thanks!

I also have a copy of the Project CHECO report "COMBAT SNAP: AIM-9J
Southeast Asia Introduction," but Guy addressed the issue for you.

Would you mind posting some other details from these both reports?

No problem...anything you're looking for, specifically? The Rivet
Haste report is only 22 pages. The COMBAT SNAP report is about 30 or
so pages long.


Hmm, ideally all those 52 pages will be fine. ;-)

But more seriously, I dont know what is in this reports included,
generaly I am looking for some technical descriptions and info about
operational use.

Cheers
Ivan

In article ,
(Zajcevi) writes:
Hello

Many thanks for all answers here, I needed some time to sort
everything what was writen here and I got some additional questions.

Guy Alcala wrote in message ...

APQ-72 (F-4B) and APQ-100 were almost identical for A-A use, the main
difference being that the Air Force required the latter to have an
adjustable range strobe for bombing (not a very useful feature, actually,
given the way it was implemented). IFF interrogators were later added to the
APQ-100 and 109 at least, APX-76 IIRR.

So the first APQ-72s and APQ-100s/109s were without any IFF systems?
When they have been added?
Was APX-76 used on F-4Js/Es, and also Combat Tree birds?

Walt Bjorneby, who'll hopefully chime in, has stated in the past that the
APQ-109 was longer-ranged than the APQ-120, owing to the larger antenna.
Basic A-A options were a normal B-scan search and lock-on mode, Boresight,
or Gyro Out,

Have I understand it correctly?
A-A
1. B-scan - basic mode used for search
2. Lock-on - once was target acquired in B-scan, it was tracked in
Lock-on and it also provided illuminating for AIM-7s

ALso known as an F-Scope. The pipper deflection is governed by
bearing rate. If the target is on a steady bearing, the dot's in the
middle, if it's moving in one or more axis, the dot moves to show it,
The amount of deflection of the dot is the rate of change. There's
also an Artificial Horizon bar, so's you don't fly into the ground
while sqinting at the scope, and a couple of concentric rings that
show you time to some range marker (Rocket fire for, say, an F-86D or
F-89, or the Max and Min rages that the interlock ciruits will allow
for Guided Missile firing, and how fast you're closing on the target.
Somewhere in there will be an antenna Az & El marker, too.
It sounds very complicated, but it was determined in the 1950s to be a
good way to get intercept info to a pilot.

Lock On, BTW, is when the radar is given a target at a particular
Azimuth, Elevation, and Range and told to follow it automatically.

3. Boresight - used during dogfights, generally radar looked at the
same point like pipper. In another topis about F-4E some time ago
Dweezil Dwarftosser wrote about some Auto Acq mode and his
generations. Was Auto Acq submode of Boresight or it is only another
designation the same mode?

Boresight is aligned with the gunsight pipper. Put the pipper on the
target, and, either the Guy In Back or, in some mods, the Pilot locks
on. With Auto Acq, the radar automatically starts tracking the
closest object on the pipper's sightline.

4. Gyro out - another one used in dogfights

5. TV - used only on F-4Es with TISEO

Were there any other modes or submodes, or some differences dependable
on F-4 version?

A-G
From another topis about F-4E byDweezil Dwarftosser:
MAP-B - ?

A B-scan showing the ground map. This ends up being very at the edges
and bottom end of the scope, because angle measurements are translated
into the Y coordinate of the scope. Think Mercator Projection,
especially toward the poles.

MAP-PPI - for offset bombing
A more usable map, where the angular deflection is actually angles,
giving a pie slice shaped display, in most airplanes. It's good for
Navigating, too.

A/G - ranging for boms, rockets, guns

The radar tracks the reflection from the ground in front. With a
ground map, it's also possible to put a range/angle cirsor on a
prominent point a known bearing/distance fron the target and use that
offset as a reference for bombing calculations.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

On 12 Aug 2003 15:21:56 -0700, (Zajcevi) wrote:

5. TV - used only on F-4Es with TISEO

1967 Walleye on F-4Ds out of Ubon, Thailand.
The debriefings I caught they blew a barge out of the water next to a
dock, and flew a bomb into a cave.

http://www.fas.org/man/dod-101/sys/smart/agm-62.htm
"Air Force began Walleye combat tests in Vietnam during August 1967
that achieved excellent results in good visibility against targets
that gave a strong contrast and were lightly defended."

(Peter Stickney) wrote in message ...
3. Boresight - used during dogfights, generally radar looked at the
same point like pipper. In another topis about F-4E some time ago
Dweezil Dwarftosser wrote about some Auto Acq mode and his
generations. Was Auto Acq submode of Boresight or it is only another
designation the same mode?

Boresight is aligned with the gunsight pipper. Put the pipper on the
target, and, either the Guy In Back or, in some mods, the Pilot locks
on. With Auto Acq, the radar automatically starts tracking the
closest object on the pipper's sightline.

So boresight was a different mode than Auto Acq, or Auto Acq was
development of boresight (used and APQ-72/100/109) which was used on
APQ-120 and eventually APG-76?

APQ-72/100 radar dish had diameter 81 cm. Do you know these number for
the later types? F-4D/J had more bulbous nose than their earlier
version and this could be only becouse of larger diameter of radar
dish. APQ-120 on F-4E has on the other side smaller antenna.

Ivan

In article ,
(Zajcevi) writes:
(Peter Stickney) wrote in message ...
3. Boresight - used during dogfights, generally radar looked at the
same point like pipper. In another topis about F-4E some time ago
Dweezil Dwarftosser wrote about some Auto Acq mode and his
generations. Was Auto Acq submode of Boresight or it is only another
designation the same mode?

Boresight is aligned with the gunsight pipper. Put the pipper on the
target, and, either the Guy In Back or, in some mods, the Pilot locks
on. With Auto Acq, the radar automatically starts tracking the
closest object on the pipper's sightline.

So boresight was a different mode than Auto Acq, or Auto Acq was
development of boresight (used and APQ-72/100/109) which was used on
APQ-120 and eventually APG-76?

As I recall it, Auto Acq was a development of Boresight. If my
memory's correct, Boresight still required the WSO/RIO/Pilot tp place
the Range Gate over teh target and initiate tracking. (In the
early days of U.S.A.F. F-4 operations, bith seats were filled by rated
Pilots. The Guy in Fron was labelled as the Aircraft Commander, and
the Backseater was the Pilot. (Yes, it doesn't make any sense)
With Auto Acq, the pilot/Aircraft Commander held the pipper on the
target, and a single switch action would cause the radar to track the
nearest target.


APQ-72/100 radar dish had diameter 81 cm. Do you know these number for
the later types? F-4D/J had more bulbous nose than their earlier
version and this could be only becouse of larger diameter of radar
dish. APQ-120 on F-4E has on the other side smaller antenna.

The inital version of the Navy F-4, the F-4A, had a 24" (61cm)
antenna. This wasn't providing the acquisition range that was
specified, so the antenna was enlarged to 32" (81cm). This size was
used for the F-4B, F-4C, F-4D, and the F-4J. The F-4E's APQ-120 had a
smaller elliptical antenna roughly 18" X 27" (46 x 69 cm) With teh
smaller antenna, and the use of solid-state electronics in the radar
itself, there was enough volume freed up in the nose for the gun adn
its ammunition drum.


--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

Zajcevi wrote:

Hello

Many thanks for all answers here, I needed some time to sort
everything what was writen here and I got some additional questions.

Guy Alcala wrote in message ...

APQ-72 (F-4B) and APQ-100 were almost identical for A-A use, the main
difference being that the Air Force required the latter to have an
adjustable range strobe for bombing (not a very useful feature, actually,
given the way it was implemented). IFF interrogators were later added to the
APQ-100 and 109 at least, APX-76 IIRR.

So the first APQ-72s and APQ-100s/109s were without any IFF systems?

Without IFF interrogators. They always had transponders.


When they have been added?

Don't remember offhand, but will try and check.

Was APX-76 used on F-4Js/Es, and also Combat Tree birds?

No idea. The diagrams of F-4E cockpits I've got show the IFF interrogator panel (in the RCP, left of the radar scope) as a
blank panel, but photos show that it is indeed for that purpose. Unfortunately, the label can't be seen. Photos of the
back cockpit of F-4Gs show a panel labeled APX-80 in the same spot.

Walt Bjorneby, who'll hopefully chime in, has stated in the past that the
APQ-109 was longer-ranged than the APQ-120, owing to the larger antenna.
Basic A-A options were a normal B-scan search and lock-on mode, Boresight,
or Gyro Out,

Have I understand it correctly?
A-A
1. B-scan - basic mode used for search

Yes.

2. Lock-on - once was target acquired in B-scan, it was tracked in
Lock-on and it also provided illuminating for AIM-7s

Yes, with both manual or auto-tracking available, in both range and/or azimuth/elevation.

3. Boresight - used during dogfights, generally radar looked at the
same point like pipper.

Always aligned with the pipper, until lock-on achieved, then it would auto-track the target.

In another topis about F-4E some time ago
Dweezil Dwarftosser wrote about some Auto Acq mode and his
generations. Was Auto Acq submode of Boresight or it is only another
designation the same mode?

Auto-acq allowed an automatic acquisition and lock-on while in boresight or later, in CAA mode. Essentially, it eliminated
the need to manually position the range gate around the target.

4. Gyro out - another one used in dogfights

Yes.

5. TV - used only on F-4Es with TISEO

F-4Ds equipped for A/G PGM use had a separate TV, the Sony scope.

Got to go, I'll finish my reply later.

Guy


Were there any other modes or submodes, or some differences dependable
on F-4 version?

A-G
From another topis about F-4E byDweezil Dwarftosser:
MAP-B - ?
MAP-PPI - for offset bombing
A/G - ranging for boms, rockets, guns

Were there any others?
How was called mode when adjustable range bombing strobe on F-4C was
used?
The some for additional modes for F-4D?

APG-59 was a high PRF Pulse Doppler (alternatively pulse) set, with a
considerably higher average power in PD mode than the earlier sets. Good
for head-on detection of look down targets, at least over water, and
apparently considerably longer ranged on closing targets than the pure
pulse sets, at least when ground clutter wasn't a problem. Friedman's
"U.S. Naval Weapons" states that it was credited with detecting a 5 sq. m.
target at 60nm, which should be considerably better than the other radars
were capable of.

APG-59, APQ-120 were both low/ high PRF, APQ-72/100/109 were only low
PRF?
Have APG-59 some different operational modes like USAF types?

Regards
Ivan

Guy Alcala wrote:

Zajcevi wrote:

snip previous post details

Got to go, I'll finish my reply later.

Guy

And finishing the rest:

Were there any other modes or submodes, or some differences dependable
on F-4 version?

A-G
From another topis about F-4E byDweezil Dwarftosser:
MAP-B - ?
MAP-PPI - for offset bombing
A/G - ranging for boms, rockets, guns

Already answered by others.


Were there any others?
How was called mode when adjustable range bombing strobe on F-4C was
used?

That seems to be part of various nuclear bomb deliveries, rather than having a specific "mode" to itself. The bombing range
strobe appears when "MAP-PPI" mode is selected. Here's what the F-4C-34-1-1 says:

"Bombing Range Strobe. In PPI mode, the bombing range strobe is a series of straight lines which take the form of a true arc
of a circle. This strobe is ground adjustable to be displayed at a point between 0 to 50 miles. The bombing range strobe is
used as a range reference when bombing blind ground targets in conjunction with the sequential timer of the ARBCS [Guy note:
Attitude Reference and Bombing Computer Set]."

and elsewhe

"The bombing range strobe is present with the MAP-PPI display. The strobe must be precisely adjusted (using ground test
equipment) so that the outer edge of the strobe represents a predetermined range at a given altitude AGL."

Since this is really just for nuke deliveries, info on using it doesn't appear in the -34-1-1, but in the confidential or
secret supplements (-34-1-1-1 or -34-1-1-2). Ed has described how the strobe was used.


The some for additional modes for F-4D?

Can't help there, except to say that the F-4D's WRCS could accept range and probably slant angle and even velocity inputs from
a ground radar lock, in Dive Toss mode. The F-4C was pretty much manual, loft or LADD.

APG-59 was a high PRF Pulse Doppler (alternatively pulse) set, with a
considerably higher average power in PD mode than the earlier sets. Good
for head-on detection of look down targets, at least over water, and
apparently considerably longer ranged on closing targets than the pure
pulse sets, at least when ground clutter wasn't a problem. Friedman's
"U.S. Naval Weapons" states that it was credited with detecting a 5 sq. m.
target at 60nm, which should be considerably better than the other radars
were capable of.

APG-59, APQ-120 were both low/ high PRF, APQ-72/100/109 were only low
PRF?

No, the pulse radars (including APQ-120) were all low PRF. AFAIK ALL pulse radars are low PRF. Here's a (reasonably) concise
definition of the three PRF classes, from Stimson's "Introduction to Airborne Radar":

"Because of the tremendous impact the choice of PRF has on performance, it has become customary to classify airborne radars in
terms of the PRFs they employ. Recognizing that the regions of unambiguous range and and unambiguous doppler frequency are
very nearly mutually exclusive, three basic categories of PRF have been established: low, medium, and high."

"These are defined in terms not of the numerical value of the PRF per se, but of whether the PRF is such that the observed
ranges and/or doppler frequencies are ambiguous. While exact definitions vary, all are similar. The following is a widely
used, consistent set of definitions:"

"A low PRF is one for which the maximum range the radar is designed to handle lies in the first range zone. In the absence of
return from beyond this zone, _range_ is _un_ambiguous."

"A high PRF is one for which the observed doppler _frequencies_ of all significant targets are _un_ambiguous."

"A medium PRF is one for which neither of these conditions is satisfied. Both _range_ and _dopppler_ are _ambiguous_."

"Which category a particular PRF falls in depends to a considerable extent on the operating conditions. A PRF of 4 kilohertz
-- first range zone extending to 20 nautical miles -- would be 'low' if the maximum target range were _less_ than 20 nm. Yet
the same PRF, 4 KHz, would be 'medium' if the maximum range were greater than 20nm and the spread between maximum positive and
negative doppler frequencies exceeded 4 KHz."

"Similarly, a PRF of 20 KHz might be 'medium' for a 3-centimeter radar (X-band), yet 'high' for a 10-centimeter radar (S-band)
if, say, the radar's velocity were 200 knots and the velocity of the fastest target, 1,000 knots -- maximum closing rate 1,200
knots."

"In practice, not all of the possible PRFs within each category are used for any one radar band. at X-band, for example, PRFs
in the low category typically run from 250 to 4000 hertz; PRFs in the medium category are on the order of 10 to 20 kilohertz;
PRFs in the high category may range anywhere from 100 to 300 kilohertz."

To put this in perspective, the APQ-100 PRFs vary from 330 to 1,060 Hertz, depending on the mode and range selected. APG-59
was probably operating up around 200 kilohertz in Pulse Doppler mode.

Have APG-59 some different operational modes like USAF types?

I'm sure it does but I don't know what they are, other than a high PRF Pulse Doppler mode that the USAF types lack.

Guy

Guy Alcala wrote:

Zajcevi wrote:

How was called mode when adjustable range bombing strobe on F-4C was
used?

That seems to be part of various nuclear bomb deliveries, rather than having a specific "mode" to itself. The bombing range
strobe appears when "MAP-PPI" mode is selected. Here's what the F-4C-34-1-1 says:

"Bombing Range Strobe. In PPI mode, the bombing range strobe is a series of straight lines which take the form of a true arc
of a circle. This strobe is ground adjustable to be displayed at a point between 0 to 50 miles. The bombing range strobe is
used as a range reference when bombing blind ground targets in conjunction with the sequential timer of the ARBCS [Guy note:
Attitude Reference and Bombing Computer Set]."

and elsewhe

"The bombing range strobe is present with the MAP-PPI display. The strobe must be precisely adjusted (using ground test
equipment) so that the outer edge of the strobe represents a predetermined range at a given altitude AGL."

Since this is really just for nuke deliveries, info on using it doesn't appear in the -34-1-1, but in the confidential or
secret supplements (-34-1-1-1 or -34-1-1-2). Ed has described how the strobe was used.

The nuke delivery in the F-4C was done with a two stage timer. You
would calculate the distance to the target at a pre-determined ground
speed from a known IP (initial point). This could be a visual
landmark, or a set distance from a ground radar return. If choosing a
VLD/RLD (Visual or Radar Laydown Delivery), you started the timer by
depressing the pickle button at the IP (when the radar bomb strobe
touches the target or IP radar blip) then flew straight ahead at fixed
speed. When the timer expires the blivet is released.

Or if lofting the bomb in a VLADD/RLADD (Visual or Radar Low-Angle
Drogue Delivery), two timer settings were used. Same IP definition,
either visual landmark or intersection of the bomb strobe and blip.
Pickle and hold, maintain airspeed until first timer setting elapses
then start four-G pull up straight ahead for second timer run (usually
about six or seven seconds). Bomb releases in climb at about 30-45
degrees of pitch and flies forward to the target in a ballistic arc. A
"drogue" chute deploys based on a bomb timer to stabilize the bomb and
slow descent until a radar ranging mechanism detonates the bomb at a
preset height above the ground (air burst rather than the ground
burst of the laydown delivery). The delivery aircraft completes a
wing-over and escapes about 90-135 degrees off the original run-in
course.

The strobe was screw-driver adjustable and was manually tweaked by the
WSO against the BIT (built-in test) range marks generated during radar
pre-flight checks. Usually five or four mile range was used in range
work.



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