Question for Walt B. (F-4D/APS-107)
g_al...@hotmail.com
topic (which had drifted quite a bit). I'd asked them for a description
of its display, but Ed only flew the D a little, and Dweezil's knowledge
of it was secondhand. IIRR, you flew the D model a lot, could you
describe how the display differed from the typical APR-25/-26 or
APR-36/-37's azimuth strobe and separate threat warning panel lights?
Dweezil was told that it actually displayed the strobe on the radar
display itself, although it rarely worked as it was supposed to. Every
source I've ever seen on the version of the APS-107 in the F-4D has
described its display as confusing, and the system as unreliable.
What's your experience?
TIA,
Guy
Sent via Deja.com http://www.deja.com/
Before you buy.
Walter Bjorneby
at DaNang. My Ds in the 390th just had the APS ? (CRS) without all the magic
symbology. (They had been in SEA about 7 years or so, right out of the
factory) We could get a strobe on the RHAW scope and that was good fro a
clock position but mainly I listened to the raw audio since I could tell
from the tone what was looking at me - Firecan or SA2, mainly; rarely a GCI
site or Height Finder. (Thanks to all that ADC experience!).
Never ever saw any RHAW info on the ship's FCS radar scope. Would have
pizzled the hell out of me because until you mentioned it I didn't know any
gear did that. Was it for
firing Shrikes? None of our birds had that equipment and I don;t think ever
flew one that had it working.
Walt BJ ftr plt ret
Ed Rasimus
That's interesting. The D's that I flew (fortunately only once or
twice) all had APS-107. The only other RHAW in use was APR 25/26 in
the '66 to '70 period and then APR 36/37 from '70 to '73. We were
getting retrofitted on our Korat E's with ALR-46 in '73 (but they
never upgraded the C's I flew out of Torrejon for the next four
years.)
The APS 107 didn't have a RHAW scope. It simply had a TDU (Threat
Display Unit) which was lights in various colors. If you were looking
at a vector scope, you were using something other than an APS-107.
And, regardless of whether you were looking at 25/26, 36/37, 107 or
46, you were never hearing "raw" audio--it was always processed
signals. If you wanted raw audio you needed to carry a Shrike--and
I'll guarantee you'd be impressed with the stuff that the missile
heard that the RHAW gear didn't.
The APR 36/37 was my favorite, because I got enough experience with it
to fully trust the output. I recall the first Pack VI sortie I took my
dedicated WSO on--he was a C-141 nav retrained in the F-4 and we got
crewed together during the gap between LB I and II. The first launch
tones started about Banana Valley and I reassured him that we would
hear a lot of them, but they were spurious. I would tell him when it
was "real". Sure enough, about 5 minutes later we got the first one
and it stands out very clearly from the normal background clash and
clatter. No doubt at all about it.
Ed Rasimus
Fighter Pilot (ret)
*** Ziff-Davis Interactive
*** (http://www.zdnet.com)
Dweezil Dwarftosser
> [...] If you wanted raw audio you needed to carry a Shrike--and
> I'll guarantee you'd be impressed with the stuff that the missile
> heard that the RHAW gear didn't.
The F-105G crews would often replay their intercom cassettes in
debrief. Amazing audio activity.
The AGM-78s most often would pick up, analyze, lock up and be ready
to go a minute before the first hint of sizzles on the RHAW audio.
- John T.
news
F-4, I have managed to spend a significant amount of time working on the
APS-107. As originally envisioned, the F-4D was to be the new "Wild Weasel"
replacement in 1966-67. To promote that end, the aircraft was fitted with a
Bendix Radar Homing and Warning system otherwise known as the APS-107. This
system had the primary warning functions that we see in the APR-25/26, and
the APR36/37. This function was accommodated by your normal install of 4
quadrant antennas and the low band missile warning blade. There were two
light panels and 2 Azimuth displays that functioned pretty much the same as
the other sytems. But, to support the "Wild Weasel" function, to provide
homing information to radars of interest, there were 4 additional antennas
installed on the 4 quadrants of the nose. This was so one could point the
nose at the target and hopefully the AGM-45s would also see the target. This
was the radar scope display mentioned above. there was a switch that removed
the radar information from the ICU and put in the direction information from
the APS-107. This was available in both cockpits.
I have never seen this function work correctly on any F-4D, either in the
Wolf Pack (67-68) or when I worked at Air Asia (70-75). This is probably why
the antennas and the homing function were removed from the F-4D starting, I
believe, in 1970.
This system was very sensitive and performed really great when it was
working. Unfortunately, the Bendix harness that was used in this
installation was very crappy and any time you removed a system component
(all over the airplane, maybe 20 or so boxes not counting antennae) as often
as not you would break a wire or a coax. And they were a bear to fix,
because of the heavy metal braid on all the wire bundles.
Some years later (1983 or 84) I saw a former 25th TFS F-4D (66-8797 or
therabouts) at an air show in Pensacola and the APS-107 had been replaced by
the ALR-46.
"Walter Bjorneby" <wal...@oneimage.com> wrote in message
news:398F6A90...@oneimage.com...
g_al...@hotmail.com
thu...@rmii.com (Ed Rasimus) wrote:
> Walter Bjorneby <wal...@oneimage.com> wrote:
>
> >Sorry, troops; I don't ever recall seeing an APS 107 neither
stateside nor
> >at DaNang. My Ds in the 390th just had the APS ? (CRS) without all
the magic
> >symbology. (They had been in SEA about 7 years or so, right out of
the
> >factory) We could get a strobe on the RHAW scope and that was good
fro a
> >clock position but mainly I listened to the raw audio since I could
tell
> >from the tone what was looking at me - Firecan or SA2, mainly; rarely
a GCI
> >site or Height Finder. (Thanks to all that ADC experience!).
> >Never ever saw any RHAW info on the ship's FCS radar scope. Would
have
> >pizzled the hell out of me because until you mentioned it I didn't
know any
> >gear did that. Was it for
> >firing Shrikes? None of our birds had that equipment and I don;t
think ever
> >flew one that had it working.
> > Walt BJ ftr plt ret
>
> twice) all had APS-107. The only other RHAW in use was APR 25/26 in
> the '66 to '70 period and then APR 36/37 from '70 to '73. We were
> getting retrofitted on our Korat E's with ALR-46 in '73 (but they
> never upgraded the C's I flew out of Torrejon for the next four
> years.)
>
> The APS 107 didn't have a RHAW scope. It simply had a TDU (Threat
> Display Unit) which was lights in various colors. If you were looking
> at a vector scope, you were using something other than an APS-107.
> And, regardless of whether you were looking at 25/26, 36/37, 107 or
> 46, you were never hearing "raw" audio--it was always processed
> I'll guarantee you'd be impressed with the stuff that the missile
> heard that the RHAW gear didn't.
Walt, Ed's recollection and all the sources I can find agree that the D
was originally fitted with the APS-107, and they imply that it was used
throughout the Vietnam period. Later ALR-46 (I think) was added (button
antennas on the donkey dick and drag chute door), and according to one
source they were used together.
It seems to me there's a couple of possibilities here. One is that the
Vietnam units were so disgusted with the APS-107 that a/c deployed there
had their APS-107s replaced by APR-25/26 or, more likely, APR-36/37.
Another possibility is that you had an updated version of APS-107, which
changed to a vector scope, and the a/c Ed flew hadn't been so updated
(they were all from TDY squadrons). The F-4D apparently was fitted (at
least initially) with the APS-107A. Some navy a/c used the APS-107B
(don't know how that differs from the A), and I saw an APS-107E version
mentioned somewhere once.
One thing that's always puzzled me, is about where the forward antennas
for the APS-107 were. Many sources state that the donkey dick was
reintroduced on the F-4D (many early a/c lacked one) to house the
APS-107 antennas and/or part of the equipment itself. OTOH, there are
numerous shots of F-4Ds in Vietnam that have four diamond-shaped
antennas around the nose, just aft of the radome, and spaced about 90
degrees apart at roughly the 10:30, 1:30, 4:30, and 7:30 positions, and
some sources say those were for APS-107. I've got photos showing those
antennas on Ds belonging to the 8th, 12th, 366th and 432nd wings in
Vietnam.
The odd thing about it is that those same antennas are also credited (in
Larry Davis' book "Wild Weasel") as part of the Az-El system added to
the F-105F, 'EF-4C,' and A-6B Mod 0. This allowed an emitter to be more
accurately located, and also allowed the location to be displayed on the
pilot's gunsight combining glass. What's even odder is that these
antennas seem to appear, disappear, and then reappear on some F-4Ds.
There's one sequence of shots (in "And Kill MiGs") of a Udorn bird,
66-7554, supposedly taken at roughly 1 year intervals from 1970 to 1972,
in which they are present, missing, and then present again. It appears
that they're more likely to be missing than present by 1971-72, and they
seem to have been removed from all Ds postwar, although you can usually
see the mounting plates where they had been.
As to how long the 390th had their birds, according to my best source,
they re-equipped with the D by January 1968. I've got serials for only
two a/c, 66-8800/BX 'Roadrunner', and 66-8805/BT 'William Lee', both
very late in the 'D' production run. I take it the 390th had changed to
'LF' codes by the time you assumed command?
g_al...@hotmail.com
"news" <robe...@mail.idt.net> wrote:
> As a phormer Phantom phixer with 9 years on all (American) models of
the
> F-4, I have managed to spend a significant amount of time working on
the
> APS-107.
<snip>
Boy, I wish I'd seen this reply before I wrote my last post. Talk about
having your questions answered before you ask them! Thanks for clearing
up the mystery of the diamond-shaped weasel antennas for me: I knew that
a couple of F-4Ds had served as prototype weasels before the decision
was made to mod the F-4E instead, but wasn't aware that so many were
fitted with the Az-El antennas as part of an all-a/c weasel mod. It
seems those same antennas served IR-133/ER-142/ALR-53/APS-107 at various
times, depending on the a/c.
Now, the only thing we have to wonder about is why the Ds Ed flew were
lacking the Vector scopes.
Walter Bjorneby
I heard equated, to me, to that radar's PRF, except fpr the nasty noises
associated with SA2.
Low purr for GCI (slow PRF) medium for Firecan, higher pitched for fighter
radars.
Rattlesnake and real high pitch for SA2.
So the TDU was the APS107 - yeah we had them but I d forgotten what it was
called.
The strobe meant more to me anyway. I suppose we had APS 25/26; we normally
(ha!) worked in-country because our gear was hard to maintain while the 4th
and the 421st(worst) went North more. Although we did get the job of digging
the SAM vans out of MR1 after they came across the DMZ in 72.
The 366th DM consciously held back maintenance on our WCS and RHAW gear to
concentrate on the F4E until we too had to go North. Then we had a bitch of
a time fixing all the delayed discrepancies on the WCS and RHAW gear. I
complained a lot about his policy but he was an O-6 . . .
Yeah we had LF on the tail.
When I got command in Dec 71 the 390th had just failed a PACAF maintenance
inspection and each bird was carrying about 225-250 dleayed writeups.
Nothing serious that would keep the birds from flying and dropping iron
bombs using the optical sight .... but about 2 months of hard work to clean
up.
The RHAW isntallation was a PITA because baing an afterthought ti was stuck
in many places all tied together with real skinny fragile coax cable. Some
boxes were behind panel 22 over the wing - a long skinny mother fastened in
with screws. Theyw ere always breaking off and requiring sheet metal to fix.
And if you moved the bird with that panel off you had to jack the bird to
get the panel to fit. Always 2 hours extra because of those bloody screws.
Bloody McD design that went right along with putting the UHF radio under the
WSO's seat . . .The E was a lot easier to maintain which was why we sucked
hind tit.
But it worked ok I guess - I'm still here and you can hear the chirps and
buzzes and cricket noises on my audio tapes still.
WAlt Bj ftr plt ret
Dweezil Dwarftosser
mysteries about the APS-107.
"news" <robe...@mail.idt.net> writes:
[ snipped all the good stuff...]
> This system was very sensitive and performed really great when it was
> working. Unfortunately, the Bendix harness that was used in this
> installation was very crappy and any time you removed a system component
> (all over the airplane, maybe 20 or so boxes not counting antennae) as often
> as not you would break a wire or a coax. And they were a bear to fix,
> because of the heavy metal braid on all the wire bundles.
Was that the microdot coax? (About 3/16ths in core diameter, with heavy,
stiff braid but only a single/double strand center conductor.) The
whole thing spiral wrapped in thick, strong, white teflon wrap?
The Westinghouse radars (F-4) used lots of it, and I recall seeing
quite a bit of the stuff tied in to the RHAW gear.
- John T.
g_al...@hotmail.com
Walter Bjorneby <wal...@oneimage.com> wrote:
> Sorry about 'CRS'.
Walt, given that we're often talking about 28 or more year-old memories
of fairly minor equipment designations, I think you, Ed, John, Robert
and others like you remember far more than most people would, and far
more accurately than most, and I and others on r.a.m. are very much
aware of and appreciative of it.
<snip>
> So the TDU was the APS107 - yeah we had them but I d forgotten what it
was
> called.
> The strobe meant more to me anyway. I suppose we had APS 25/26; we
normally
> (ha!) worked in-country because our gear was hard to maintain while
the 4th
> and the 421st(worst) went North more.
<snip>
It appears from Robert's post that the vector scope was part of the
APS-107, not APR-25 or APR-36. Which still leaves the mystery of why
the Ds Ed flew were missing the scope entirely.
Robert's info has allowed me to understand labels on two switches that
never made sense before. Checking cockpit diagrams of the D (in the
Detail & Scale book on the C and D), I found that it had not one but two
switches left of the throttle quadrant in the F/C/P which control where
the APS-107 _homing_ info is displayed. There are two two-position
toggle switches; the forward switch controls what's displayed on the
gunsight combiner glass, the after switch what's displayed on the radar
display. When aft position is selected on either switch, then the
normal info ("ASG-22 LCOSS DIS" and "APQ-109 DVST DIS", respectively) is
displayed.
Flipping the respective switch to the forward position sends the APS-107
homing data ("DIS-107" in both cases) to the respective display instead.
I don't know whether the capability for the gunsight display was
actually implemented on the F-4D (Robert?), but that capability
definitely was available on the F-105F (when it worked). I've been
unable to find similar switches in the R/C/P, but this is a bird modded
for Pave Spike, so maybe they've been removed.
Presumably the E only had one of these switches, as John mentioned. On
the E cockpit diagram I have, it's either been removed/replaced or else
deliberately not shown). In roughly the position of the aft switch is
what appears to be a three position toggle, labeled "APU-REJECT."
Forward is "NORMAL", middle is "REJECT", and aft is "TEST". Can anyone
explain what that did?
Thanks again to all for their answers and info. Personally, I find I
often find out the answers to otherwise insoluble questions from little
asides like Walt's description of Panel 22's quirks or Robert's
description of the wiring, as there is often no obvious logical
connection between a particular piece of equipment and why something
is done a certain way.
Which reminds me: Robert's statement that the APS-107 diamond antennas
were removed starting in 1970 or so, which jibed with my own
observations that they seemed to be mostly missing in 1971-72, lead me
to re-examine that sequence of photos purporting to show an F-4D
assigned to the 432nd, 66-7554, over a three year period, with the
antennas present, missing, and then present again. I'm always leery of
captions as they're often wrong, and especially leery of dates in
captions.
Given Robert's comments, I re-examined the "last" photo in the sequence,
to see if I could put the lie to it being taken in 1972 and show that it
was more likely taken earlier. I think it almost certainly was taken
prior to 1972, and in fact probably earlier than 1970. Chalked on the
left side of the nose, just forward of the "installed armament" panel
(don't know what its "official" name is, but it's the rectangular 'box'
where the ordies chalk the weapons load), are the words "CREW V" and
under that "433rd" or maybe "435th". In both the other two shots, you
can see the tail codes, and the a/c is definitely part of the 555th at
Udorn at the time ("OY" codes). The shot in question only shows the
left side of the nose area of the a/c, but the "433rd or "435th" shows
that it's part of the 8th at Ubon, not the 432nd at Udorn.
Of course, the a/c could be assigned to the 8th in 1972, but there's a
couple of details that make me think not. For one, it's lacking the
electro-luminescent formation-keeping light strips. While apparently
not universally installed by 1972, they were on many if not most a/c by
then (BTW, anyone know when they first appeared? I'm tentatively saying
1970, although one photo purportedly taken in November 1968 shows an a/c
with them. I've got my doubts on the date). Oh, and does anyone know
if the "installed armament" panel was moved to the intake flank just
above and forward of the wing leading edge because of the installation
of the strip light on the side of the nose, or just because with the
boarding ladder installed the original location was hard to see/write
on?
Second, the inside of the forward landing gear door is painted in a dark
color (red, blue, green, black?) with the "last three" painted in very
large, probably white numerals on it. Almost all photos of F-4s show
the inside of the door painted white, but the 8th did paint at least
some F-4D a/c like that, with numerals that size, during the RT period
and possibly into the bombing halt (the 388th also painted some of their
Es this way, during the bombing halt). I don't know if the inside of
the door was painted in squadron colors or not. I've never seen a photo
of a 432nd bird painted this way.
Finally, the kill stars in this particular photo are of a style
and size typical of the 8th in RT, i.e. red with white outlines. Many
(by no means all) shots of 432nd a/c tend to show plain red stars, or
else red with a different color center dot; both photos of the a/c when
it is definitely assigned to the 432nd show such kill marks.
While all of this is circumstantial, and none of it positively
eliminates the photo as being from 1972, I think the preponderance
of evidence makes it likely that the caption is wrong on the date.
Ed Rasimus
>; we normally
>(ha!) worked in-country because our gear was hard to maintain while the 4th
>and the 421st(worst) went North more.
Say what you want about airplanes, ECM gear, zippers and spurs, but
don't talk nasty about my first fighter squadron. Of course, when I
was in the 421st, it was the "Fighting Cavaliers" rather than the
Black Widows "Kiss of Death" and we flew single seat, single engine
fighters downtown.
Today, of course, the 421st is equipped with Vipers as part of the
388th TFW at Hill. Lots of guys don't know that the reason they are
Black Widow is that the original squadron established for only 18
months during 1943/44 in the Pacific flew P-61s.
Dweezil Dwarftosser
[ big snip ]
> Of course, the a/c could be assigned to the 8th in 1972, but there's a
> couple of details that make me think not. For one, it's lacking the
> electro-luminescent formation-keeping light strips. While apparently
> not universally installed by 1972, they were on many if not most a/c by
> then (BTW, anyone know when they first appeared? I'm tentatively saying
> 1970, although one photo purportedly taken in November 1968 shows an a/c
> with them. I've got my doubts on the date).
I'm not absolutely certain, but I seem to recall that F-4E 69-7551's
arrival at Korat early in 1971 marked the first time I saw the EL
panels. (It was eerily "ghostlike" taxiing at night...)
That same aircraft (fresh from the factory) also boasted the first
extended gun fairing I had seen. It was the only one on base with it.
The armament placard location appeared in either position for a number
of years; it took a depot/IRAN trip before anyone bothered to repaint
the jets back then.
> Second, the inside of the forward landing gear door is painted in a dark
> color (red, blue, green, black?) with the "last three" painted in very
> large, probably white numerals on it. Almost all photos of F-4s show
> the inside of the door painted white, but the 8th did paint at least
> some F-4D a/c like that, with numerals that size, during the RT period
> and possibly into the bombing halt (the 388th also painted some of their
> Es this way, during the bombing halt). I don't know if the inside of
> the door was painted in squadron colors or not. I've never seen a photo
> of a 432nd bird painted this way.
Only one of the 388th's units used the squadron's color (green) inside
the nose gear door, as you describe. But that is probably because the
34 TFS color was black - and they preferred large black numerals inside
the standard white-painted door.
- John T.
g_al...@hotmail.com
Dweezil Dwarftosser <wc...@usa.net> wrote:
> g_al...@hotmail.com writes:
> [ big snip ]
>
> > Of course, the a/c could be assigned to the 8th in 1972, but there's
a
> > couple of details that make me think not. For one, it's lacking the
> > electro-luminescent formation-keeping light strips. While
apparently
> > not universally installed by 1972, they were on many if not most a/c
by
> > then (BTW, anyone know when they first appeared? I'm tentatively
saying
> > 1970, although one photo purportedly taken in November 1968 shows an
a/c
> > with them. I've got my doubts on the date).
>
> I'm not absolutely certain, but I seem to recall that F-4E 69-7551's
> arrival at Korat early in 1971 marked the first time I saw the EL
> panels. (It was eerily "ghostlike" taxiing at night...)
> That same aircraft (fresh from the factory) also boasted the first
> extended gun fairing I had seen. It was the only one on base with it.
Thanks, John, we're narrowing it down.
> The armament placard location appeared in either position for a number
> of years; it took a depot/IRAN trip before anyone bothered to repaint
> the jets back then.
Do you know if it was moved because of the light strip, or because the
portable ladder was in the way, or a combination of the two? I assume
that the placard wasn't moved on a whim.
> > Second, the inside of the forward landing gear door is painted in a
dark
> > color (red, blue, green, black?) with the "last three" painted in
very
> > large, probably white numerals on it. Almost all photos of F-4s
show
> > the inside of the door painted white, but the 8th did paint at least
> > some F-4D a/c like that, with numerals that size, during the RT
period
> > and possibly into the bombing halt (the 388th also painted some of
their
> > Es this way, during the bombing halt). I don't know if the inside
of
> > the door was painted in squadron colors or not. I've never seen a
photo
> > of a 432nd bird painted this way.
>
> Only one of the 388th's units used the squadron's color (green) inside
> the nose gear door, as you describe. But that is probably because the
> 34 TFS color was black - and they preferred large black numerals
inside
> the standard white-painted door.
>
> - John T.
Yes, the paint scheme I describe is on 469th birds (well, I'm sure about
the ones with tail codes. When the 40th --> 469th first arrived, the
a/c didn't have codes). 67-0288, "Arkansas Traveler," credited as Wing
CO Col. Douglas's a/c, is lacking codes in the photo I have, but is so
painted. There is a difference between the 8th and 388th's style. The
388th either has the first two digits of the last three together, with
the last digit separate, or else all three evenly spaced, while the 8th
separated the first digit from the last two.
RJConnolly
shows up twice.
(I'm posting this from home, not work so all my names are different-but it's
still me! (robertjc))
This thread is bringing back some memories, but sometimes they are not so
clear.
Aft radar display 107 disconnect switch - I can't remember where it was, I
seem to remember that the aft radar scope wire bundle had a pigtail that
went off to a relay panel, the same as the fwd display. The F-4D cockpit
diagram that I have is apparently the final configuration and doesn't show a
switch in the aft cockpit. Maybe it's just old age (!!).
I do remember that the first F-4Ds with the electro-luminescent strips that
we saw belonged to the 25th TFS. That Squadron arrived at Ubon RTAFB in late
May, 1968. ( By the way, the Triple Nickle left the Wolf Pack just a week or
so before and was replaced by the 25th. Tail code changed from "FY"(8th) to
"OY"(432nd).)
The 25th came from Eglin - 33rd TFW, and all the aircraft had the Pave
Phantom configuration Loran-D, Electro-strips, and several other goodies
installed. After this, most of the Air Force F-4s in PACAF received the mod
during either PDM (periodic depot maintenance(IRAN)) or Speedline mods at
Air Asia in Taiwan. Speed line was the program that performed depot level
TCTOs without the paint and other inspections of the PDM. We were still
installing these strips on the odd F-4C and Korean F-4Ds in 1975.
I believe the later block F-4Es (48 and up) had an emergency hydraulic power
pack (thermal battery powered hydraulic pump) installed on the stabilator
actuator and was labeled "APU".
g_al...@hotmail.com
The earliest photo I have showing the strips is on a 25th TFS bird,
dated Nov. 1968, so that agrees with your memory. I was sort of loathe
to trust the date, as there are two definite errors in the caption. It
says the a/c is armed with 750-lb bombs, when they're clearly Mk.82s,
and it says that Capt. Albert Piccirillo, the pilot of the a/c
in the photo (66-8782, "Flave") is the CO of the 25th, which is highly
unlikely and contradicted on the next page which states that the CO was
Lt. Col Lloyd C. Ulrich at the time. Elsewhere in the same book
("Wolfpack", Jerry Scutts), another photo caption ID's Piccirillo as the
8th TFW Wing CO, which is certainly rapid promotion for a captain:-).
The 25th was sort of a test and development squadron that got sent to
SEA to try out all the new stuff, so it makes sense that they'd have the
latest. I take it these a/c had the original internal ARN-92 antenna at
the time, rather than the later towel rack on the spine?
> I believe the later block F-4Es (48 and up) had an emergency hydraulic
power
> pack (thermal battery powered hydraulic pump) installed on the
stabilator
> actuator and was labeled "APU".
The D&S book on the F-4E (same source I got the cockpit diagram from)
has an Air Force provided chart showing the main differences between the
F-4C, D, E, and G, and it claims Block 40 and up for the APU, so if that
"40" isn't a typo for "48" it came in somewhere in the range of 68-452
through 68-494. It also shows Block 41 and up for the "Self-Sealing
fuselage fuel cells;" I assume they really meant foamed cells?
BTW, I take it the hydraulics APU served a "get you out of Indian
country so you can eject over less hostile territory" purpose, as a
somewhat similar mod to the F-105 did?
The a/c used for the cockpit diagram in the book is a slatted bird with
the -556 mod, fitted for ALE-40 and Pave Spike and with the DSCG scope,
so it's clearly dating from sometime post-war. It doesn't have ARN-101
though. The APS-107 switch may be there in the F/C/P, just deliberately
obscured, just as the APX-81 control head in the R/C/P is (labeled a
blank panel, but you can see that it's just been darkened to eliminate
details in the photo, as is probably the case with the APS-107 switch
panel).
Thanks for your answers,
Dweezil Dwarftosser
> Yes, the paint scheme I describe is on 469th birds (well, I'm sure about
> the ones with tail codes. When the 40th --> 469th first arrived, the
> a/c didn't have codes). 67-0288, "Arkansas Traveler," credited as Wing
> CO Col. Douglas's a/c, is lacking codes in the photo I have, but is so
> painted.
I happened to take a quick snap of the wing CC's bird on the washrack
- but wouldn't you know it? I can't remember the tail number, and
the washed-out pic is no help!
http://www.geocities.com/32271q/washrack.jpg
- John T.
g_al...@hotmail.com
Probably a different a/c; at least a different paint job, with the Wing
CO stripes across the spine (they're lacking on "Arkansas Traveler").
Not to worry though, I'd bet that the a/c in your photo is "Betty Lou,"
67-308, if the CO when you took the photo was Col. Allen K. McDonald.
308 does have the over the spine, multi-colored stripe.
Pirate
this discussion was highly interessting.
I would like to ask you something not in a direct connection
with APS-107, but with one other part of equipment for F-4Ds.
Relatively recently I learned about something called APX-
80 "Combat Tree", a system for interrogation of enemy IFF
signals, built into a few F-4Ds of the 555th TFS, somewhere in
1971, and used during air-to-air combats over North Vietnam in
1972.
Did anyone of you ever worked with this item, and if yes, how
could you read what APX-80 found out?
Thanks
Pirate
-----------------------------------------------------------
Got questions? Get answers over the phone at Keen.com.
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Walter Bjorneby
on the left panel and the info about the LCOSS display but none of that
stuff was hooked up on the Ds I flew at both Homestead and DaNang. I suppose
the 'black boxes' weren't installed but never got into that. I was on test
orders so if they had been operational we wopuld have checked them out.
Would have been nice to have them working as one of our tasks after the
April72 invasion was taking out the SAM sites they'd brought down south. As
it was our own Fast Facs (Gunsmoke) would mark the SA2 van and we'd hit it.
But there were always some hiding in the weeds like the one that shot at us
south of Mu Gia pass as we were RTBing and nothing left to hit them with.
Walt Bj ftr plt ret
g_al...@hotmail.com
Pirate <muffin00...@lycosmail.com.invalid> wrote:
> Gentlemen,
> this discussion was highly interessting.
>
> I would like to ask you something not in a direct connection
> with APS-107, but with one other part of equipment for F-4Ds.
>
> Relatively recently I learned about something called APX-
> 80 "Combat Tree", a system for interrogation of enemy IFF
> signals, built into a few F-4Ds of the 555th TFS, somewhere in
> 1971, and used during air-to-air combats over North Vietnam in
> 1972.
>
> Did anyone of you ever worked with this item, and if yes, how
> could you read what APX-80 found out?
>
> Thanks
> Pirate
I'm virtually certain that John's not going to say a word:-) Having
corresponded with a pilot who'd used it, I got the impression that it
was simply a matter of "if you get an SRO (MiG-21 transponder) IFF
response from a Combat Tree interrogation, them's bad guys." Now, as to
exactly how an IFF response might differ from a normal skin paint on the
APQ-109's display, that I don't know. There've been various methods
used over the years, and I'm afraid I'm more familiar with those used by
ATC. On the Brit CH sets in WW2, using an A-scope, it was typical that
an IFF return showed below the line of a normal range sweep, where a
normal target return would show above. However, an AI radar like
APQ-109 is using a B-scan, so one method used by ATC include a blip with
slashed lines running through it, or three parallel lines (computer
generated display). You can give the blip a distinct shape, make it
oscillate, brighten it, etc. if you're looking at a raw blip, then an
IFF return will be much stronger than a skin paint, but that's of more
use with an A-scope than a B-scope. I'll be happy to see what the domain
experts can add, should any of them feel comfortable doing so:-)
RJConnolly
by the APX-76 IFF interrogator), you would only get a reponse from the bad
guys's IFF when the antenna was pointed at it. The APX-81 video was inserted
on to the b-sweep and lit it up whenever the antenna was pointed in the
right direction. Now, if you did this while your own radar was in stby then
normal returns didn't interfere with the APX video. Of course you didn't get
range info, but a quick radar look with the antenna on the target gave
enough data to sneak up on the bad guy without setting off his RWR.
<g_al...@hotmail.com> wrote in message news:8mvj02$ief$1...@nnrp1.deja.com...
g_al...@hotmail.com
"RJConnolly" <rcon...@socal.rr.com> wrote:
> Since the APX-81 used the dipole array on the APQ-109 antenna
(normally used
> by the APX-76 IFF interrogator), you would only get a reponse from the
bad
> guys's IFF when the antenna was pointed at it. The APX-81 video was
inserted
> on to the b-sweep and lit it up whenever the antenna was pointed in
the
> right direction.
So, you're saying that the return brightened more than normal as the
jizzle band swept across, for a Tree return? Of course, oOne of the
more obvious signs that you had a Tree return was that it was possible
to get contacts at previously unattainable ranges, e.g. 50-60nm on a
fighter.
>Now, if you did this while your own radar was in stby
>then
> normal returns didn't interfere with the APX video.
I take it you're referring to using Tree in its passive mode, reading
NVN GCI interrogations?
>Of course you
>didn't get
> range info, but a quick radar look with the antenna on the target gave
> enough data to sneak up on the bad guy without setting off his RWR.
H'mm. The problem with IFF antennas has always been that they rarely
have the same beam shape as the antenna they're supposed to be
supporting, making it very easy to think you're looking at this guy when
you're really looking at that guy. Presumably, that's why the RoE
specified that Friendly a/c had to be at least 15/5nm away from the
Tree target, for FQ/RQ shots, respectively.
rp
RE: APS-107
> could you
>describe how the display differed from the typical APR-25/-26 or
>APR-36/-37's azimuth strobe and separate threat warning panel lights?
The APS-107 strobes were "coded." Also the test pattern was 12 & 6
instead of the "normal" X, and seemed to take quite some time to
complete compared to the APR-25.
Misc info: The antennas on the front were log periodic antennas.
Inside looked like a 1/16 inch or so thick gold plated Christmas tree
set in foam. Some crews discovered if they switched to the forward
antennas they could still get threat warnings off the nose when the
jamming pod was operating..
matheson
"Assam Dragons", Kadena AB) but IIRC the system gave you the option of
interrogating Mode 1, 2 or 3 and the SRO, plus discrete codes in some modes
( 2 and 3?). There also were some lights on the control box as I recall.
The result was coded strobes that were superimposed on the radar sweep that
could ID target by transponder mode and code (if radar in operate) or target
azimuth (if radar in standby). As an Air-to-Mud unit we never really
practiced with it in an Air-to-Air tactical way, and most times it didn't
work (written up as inop).
Les
RJConnolly <rcon...@socal.rr.com> wrote in message
news:yHJk5.69985$LE.3...@typhoon.we.rr.com...
> Since the APX-81 used the dipole array on the APQ-109 antenna (normally
used
> by the APX-76 IFF interrogator), you would only get a reponse from the bad
> guys's IFF when the antenna was pointed at it. The APX-81 video was
inserted
> on to the b-sweep and lit it up whenever the antenna was pointed in the
> right direction. Now, if you did this while your own radar was in stby
then
> normal returns didn't interfere with the APX video. Of course you didn't
get
> range info, but a quick radar look with the antenna on the target gave
> enough data to sneak up on the bad guy without setting off his RWR.
>
>
>
>
Pirate
at least some aspects of APX-80/81.
Please, permit me, nevertheles, two further questions.
As I said, I don't have too much info about APX-80 (the
designation I've heard) or APX-81 (as RJ stated). I also don't
know how wide it was used, especially in F-4Ds. However, I
suppose that it was used - for example - during the hectic
battle on May 10th, 1972, when Maj. Robert Lodge, of the 555th
TFS, lead the Oyster-section during a MiG-CAP over North
Vietnam. Capt. Locher, Lodge's WSO on that (and several
previous) missions, picked the first two radar contacts from a
range of some 40 or more nm (over 74 kms), supposedly from dead
ahead, which is - for a target the size of MiG-21 - pretty far
away. Could it be so, that the APX-80 could indicate/detect
Vietnamese MiGs whose SRO transponders were on "active" even if
they operated out of the range/outside the envelope of F-4D's
radar?
Another point regarding the same topic seems very interessting
to me too: was APX-80 (the designation I've heard) or APX-81
(designation mentioned by RJ) a standard part of equipment on
every Phantom at that time, or only some, or if it became a
standard issue (perhaps on F-4Es?) afterwards? I must honestly
admit, that I'm looking for this information also because I'm
researching about F-4Es delivered to other Air Forces around the
world, and would find it very interessting if the USAF/NSA were
ready to share such knowlege with other allies.
g_al...@hotmail.com
Pirate <muffin00...@lycosmail.com.invalid> wrote:
> Guy, RJ, Les and Rp, thank you all for your answers, they clear
> at least some aspects of APX-80/81.
>
> Please, permit me, nevertheles, two further questions.
>
> As I said, I don't have too much info about APX-80 (the
> designation I've heard) or APX-81 (as RJ stated). I also don't
> know how wide it was used, especially in F-4Ds. However, I
> suppose that it was used - for example - during the hectic
> battle on May 10th, 1972, when Maj. Robert Lodge, of the 555th
> TFS, lead the Oyster-section during a MiG-CAP over North
> Vietnam. Capt. Locher, Lodge's WSO on that (and several
> previous) missions, picked the first two radar contacts from a
> range of some 40 or more nm (over 74 kms), supposedly from dead
> ahead, which is - for a target the size of MiG-21 - pretty far
> away. Could it be so, that the APX-80 could indicate/detect
> Vietnamese MiGs whose SRO transponders were on "active" even if
> they operated out of the range/outside the envelope of F-4D's
> radar?
Pirate, you want to buy or at least read two books, Anthony
Thornborough's "The Phantom Story," and Marshall Michel III's "Clashes,"
which will answer many of your questions. However, for right now, both
Lodge/Locher in Oyster 01, and Ritchie/DeBellevue in Oyster 03 were
flying Combat Tree equipped a/c on 10 May, and both Oyster 01 and Oyster
02 (Markle/Eaves) fired BVR from the FQ (not quite head-on, the MiGs
were on about a 150 deg. Track Crossing Angle), although the targets
were WVR at impact. And yes, a transponder allows you to contact an a/c
far outside the range at which you can get a skin paint; that's why ATC
relies on "secondary radar" (transponders) almost exclusively, rather
than skin paints ("primary radar").
Indeed, if you read "Clashes" you'll see that this capability and bad
COMSEC almost certainly led the NVN to believe that the SRO-2 was no
longer secure. Apparently, the Tree-equipped a/c were able to pick up
squawking MiGs at 50-60nm, even in ground clutter, and on several
occasions Tree contacts were called out on the radio with these ranges
given (with the crews getting their butts chewed back at base). The N.
Vietnamese (and the Soviets) were listening in all the time, so this
sudden doubling of radar range undoubtedly made them perk up. Shortly
thereafter, it was noticed that the VPAF had begun to use their
transponders much less frequently, only turning them on at turn points
and at other critical moments in intercepts, rather than using them
continuously as had previously been the case.
The first indication I ever saw that we could read MiG transponders was
in an account I read of the Oyster flight battle maybe 15 years ago.
Although Combat Tree was still never mentioned by name then (I believe
the first time it was so identified was in Ethell and Price's excellent
book "One Day in a Long War: 10 May 1972"), the account had Chuck
DeBellevue telling Ritchie at one point, "He's squawking MiG, he's
squawking MiG! Shoot! Shoot!" I think that one just slipped by the
Air Force. As it turned out, Ritchie didn't fire head-on, for reasons
I don't know, and took his shot WVR from the RQ.
> Another point regarding the same topic seems very interessting
> to me too: was APX-80 (the designation I've heard) or APX-81
> (designation mentioned by RJ) a standard part of equipment on
> every Phantom at that time, or only some, or if it became a
> standard issue (perhaps on F-4Es?) afterwards? I must honestly
> admit, that I'm looking for this information also because I'm
> researching about F-4Es delivered to other Air Forces around the
> world, and would find it very interessting if the USAF/NSA were
> ready to share such knowlege with other allies.
There seems to be some confusion in sources about the APX-80/81 , and
which was on what. Most sources seem to agree that APX-81 was the
system normally used on the F-4E, but many others say that APX-80 was
Combat Tree, on the few F-4Ds fitted with it, and I've got a cockpit
diagram of an F-4G which labels an "APX-80 Control Panel". The Gs were
all converted from FY-1969 Block 42-45 a/c.
It seems possible to me that APX-80 was the interim system, and APX-81
was the "production" system, but if anyone here knows for sure, I'm all
ears. Combat Tree was in very short supply initially: originally, there
were 8 F-4Ds transferred from the 3rd TFW in Korea, fitted with it and
assigned to the 432nd TFW at Udorn, from the end of 1971. Thornborough
lists the serials of these a/c, based on info provided to him by Alan
Howarth: 65-0783, -0784, -0785, and -0801, plus 66-0232, -0237, -7463,
and -7482. I've been able to check the serials of some of these against
known kills by Tree equipped a/c, and they match.
Typically, the flight lead and, if enough a/c were available, the
element lead would be in Tree-equipped a/c. Udorn would normally put up
two to four MiGCAP flights for a mission, so resources were stretched
pretty thin given the usual equipment failures.
The a/c can often be identified by a rectangular red warning sign on the
left intake splitter plate, which in large white letters reads:
WARNING
and below it, in smaller type
Destruct Safety Pin [or pins, the photo I have is cut off]
Must Be Installed
Prior To Ejection
Seat Maintenance
T.O. 1F-4C-2-3CL-1
This apparently referred to an auto-destruct package fitted to Combat
Tree, and which would be armed by ejection seat operation. If you've
got Lou Drendel's "And Kill MiGs," there are a couple of photos showing
this warning sign, with the closest one (where I was able to read the
stenciling above) showing Dan Cherry standing on a cockpit ladder.
There's another shot showing 66-0267 with the sign, and this a/c is
credited as the a/c John Madden was flying when he scored his twin
MiG-19 kill with AIM-9Js on 9 September; according to Red Baron, Madden
was flying a Tree-equipped a/c that mission. Red Baron normally lists
whether an a/c was Tree-equipped or not.
Attrition losses of 3 a/c by June 1972 led to another batch being
converted. He doesn't know how many a/c were converted in this batch,
but according to Mr. Howarth known serials include 66-0239, -0240, -0267
(see above), -0268, -0269, -0271, -7459, -7461, -7468, -7486, and -7501.
It seems to have become a standard fit on F-4Es subsequently. The
"Rivet Haste" slatted, T.O.-556'd F-4Es that were sent to Udorn in
September 1972 were apparently all fitted with it.
As to whether it was ever exported, I'd have my doubts. It seems
unlikely given the NSA, but we've come a long way since then, so who
knows?
Pirate
thank you really very, very much for all this exhaustive
explanations and answers. Great stuff! It really clears all of
the questions I had about Combat Tree (except that about
possible exports, but that's of little value after reading this
post of yours) and also gives good points for further readings
and research. I'll certainly follow your advices.