F-104A Radar

[Petrus]

I'm just reading "History of Air Defense Weapons 1946-1962" by Richard F. McMullen (http://www.northcom.mil/FOIA/docs/History%20of%20Air%20Defense%20Weapons,%201946-1962.pdf).

On page 316 of the PDF the author says with respect to the F-104A's radar:

The radar developed by WAD's Armament Laboratory could track a target at a range of 10 miles or less, but had no search capability.

Does anybody have any information on how the radar of the F-104A actually worked?

Piotr

 

[sferrin]

I'm just reading "History of Air Defense Weapons 1946-1962" by Richard F. McMullen (http://www.northcom.mil/FOIA/docs/History%20of%20Air%20Defense%20Weapons,%201946-1962.pdf).

On page 316 of the PDF the author says with respect to the F-104A's radar:

The radar developed by WAD's Armament Laboratory could track a target at a range of 10 miles or less, but had no search capability.

Does anybody have any information on how the radar of the F-104A actually worked?

Piotr

Sounds like a missile radar. GCI tells it where to look and then it locks on when it finds the target at that location.

 

[Michel Van]

can this help you, Petrus ?

Dweezil Dwarftosser <wcsys@usa.net> wrote:
>Quick question:>
>Were the rumors about the unusual F-104 radar dish true ?
>I never saw one with the radome open.
>>- John T., former MSgt, USAF - and member of the 1st, 4th, 15th
> 36th, 50th, 56th, 86th, and 388th ( Korat Dive Toss )
> Tactical Fighter Wings.
>

Indeed it was. The first time I saw one running (on the test bench)
I almost broke out laughing. The ASG14 was a very simple set even
compared to the to the E4(F86D). It used a spiral scan about a fixed
axis about 3 degrees (I think) below the aircraft waterline. In search
the entire antenna dish and feedhorn assembly was spinning about 100
rpm and slowly 'opened up' from dead center to 45 degrees off boresight.
That took about 3 seconds. Then it snapped back to center (the test
bench seemed to jump) and the cycle repeated. The max range on the scope
was 20 n.m. If you picked up a target the blip was a small segment of an
arc if it was 45 off axis, the length of the arc increasing as as the angle
off axis decerased until when it ws on axis the blip became a complete circle.
There was no angle track capability at all; the pilot did that by flying the
104 to point at the blip. Once inside 10nm the pilot could lock on in range
only by depressing the radar ranging button on the stick. The antenna stopped
its diverging scan and simply spun about the boresight axis. The pilot could
position a range gate over teh target and once locked on the set fed radar
range to the gunsight's ballistic computer. A needle in a gauge at the bottom
of the scope indicated overtake. The sight reticle would indicate range in nm
if missiles were selected, 1000s of feet if guns were selected. The radar was
tunable to combat ECM and also had a tunable ECM HOME function where it was in
receive-only. (This did work quite well on B52s and EB57s) There was also an IR
sight - that hafmoon window at the base of the armored windshield - that used a
scanning system like a Nipkow disc TV set of the early days. There were 2
spinning discs, one with an arc shaped slit running one way, the other
with a reverse arc. If there was no target out there, the senstive CdS
(I think) element's output was cut off by an AGC-like circuit. But a spot
IR target would result in a momentary signal and that, amplified, would
flash a neon bulb. The resulting flash would be foucssed through a pair
of similar synchronised spinning discs and that output was reflected off
the gunsight combining glass. The resulting 'arced cross' was visible to
the pilot and he flew the aircraft to put the pipper on the cross. The
range was adequate for guns, around 3-4000 feet. As simple and as crude
as it sounds, it worked! The AIM9Bs were boresighted along with the
radar and the gunsight. I got to shoot at a Firebee once and I was
tracking the drone strictly on radar. When I got a mile behind it I
called "Flares" and seconds later heard the buzzing growl in the missile.
I looked up through the sight and the pipper was on the flare. The
missile then knocked the flare off its mount. (The warhead was clipped to
save the drone - #2 got the other flare and #3 got the drone itself.

All in all the ASG14 was a simple reliable and effective weapons system - it's
simplicity was enabled by the 104's ability to catch anything it was after.

After exepriencing the slavery required to maintain an F86D/E4 and then
the F102's MG10 with its incessant need for WSEM (missile system) testing
the 104/ASG14 was a real treat. Imagine changing the radar package in 20
minutes! And aircraft availability averaged <AVERAGED> over 90%! What a
change from even the F102!

Walt BJ ftr plt ret

 

[sferrin]

Ha, ha, "Dweezil" I forgot about him.

 

[Petrus]

can this help you, Petrus ?

Yes, it absolutely can! Thank you.

And in the meantime I've found a Chinese (Rep. of China) website with the AN/ASG-14 description. http://translate.google.com/transla...ttp://www.defence.org.cn/article-1-63058.html

EDIT: Google is really our friend. I've just googled the thread (dated August 1998!) in a forum from which the quote comes

Redirecting to Google Groups

 

[Petrus]

At http://www.fighterpilotuniversity.com/alumni-house/alumni-news/zipper-at-fl-730 I've found another pilot's account on the AN/ASG-14 radar:

I don't know how familiar you are with RCA's ASG14 but it's a modern analog to the RAF's AI Mk 8 used in WW2. Basically it is a spiral scan search radar with no angle track capability. Very simple in construction and operation; just find him on the 20-mile (max!) scope, turn toward him to fly him to the center and go get him. He'll show up as a small arc on the scope when he's 45 degrees off the nose in the turn. You know when he's dead ahead (on boresight) because then he paints as a circle around the center of the scope - the circle's radius is his range. The set can, however, lock on and track a target in (only!) range from 10 miles on in. Press a button on the stick grip and the antenna reverses direction and generates about a 10 degree conical scan. The pilot has to keep the target centered by flying the airplane, as I said, since there is no angle track capability at all. It does, when locked on, feed range to the computing gunsight; effectively, too. Range numbers show up on the sight; in miles when missiles are selected, feet when guns are selected. Handily, the Sidewinders look right along the same axis and will growl when they see the target.

 

[Petrus]

From "F-104 Starfighter Units in Combat" by Peter E Davies:

Weapons were controlled with the lightweight RCA AN/ASG-14T1 fire control system, using a 24-in, pencil-beam radar antenna and independent optical and infrared sights. In Search Mode the radar displayed a range of 20 miles (40 miles in later versions) and a spiral scan pattern covering a 90-degree cone.
The difficulty, in the era before pulse-Doppler radars, of overcoming the degrading effects of ground return limited the use of Search Mode up to an altitude of about 3000 ft. Closing to within ten miles of the target, the radar could be switched to Track Mode, using a track button on the control column. The radar scan then narrowed to 20 degrees and a range strobe began to sweep between 300 and 3000 yards in auto-acquisition mode. Holding down the track button set the range strobe at the point where the button was released. Pressing the button again made the sweep range move back to zero. A pilot could thereby set the range to coincide with the target, and at that point a lock-on light illuminated and the radar started to send range information to the optical sight in order to establish correct lead angles. On his radar scope, the pilot got a ‘paint’ of the target every three seconds. A separate meter showed closure rate to the target, and the radar could be set to ‘receive only’ if it was subjected to electronic countermeasures (ECM) interference. It would then home onto the interference in ECM HOM mode.
To complete the attack the computing optical sight, with a single gyroscope, projected a reticle ‘pipper’ that was also adjustable for manual
sighting.
The AN/ASG-14 radar was sufficiently powerful for the air superiority mission, performed within visual range for which it was designed. The
concept of combat beyond visual range using much larger search radars was still some years away.

From a brochure "Lockheed L-242 Day Fighter" that was available at retromechanix.com:

Alternate Fire Control System—An alternate radar fire control system which replaced the AN/APG-34 with a new type radar had been studied and appeared to have substantial merit. This device would have eliminated the main operational limitations imposed by installing the AN/APG-34 ranging radar with the Mark 16 optical computing sight in the Lockheed Model L-242 fighter. Furthermore, it appeared to be feasible with negligible increase in equipment weight and complexity. This system included a simple lightweight search radar combined with the Mark 16 sight. To justify a change, an examination of the inherent deficiencies in the APG-34 radar was in order. Its primary disadvantage was that it was designed to supply radar range information “only” to an optical computing sight and therefore had essentially no target detection capability. In contemporary jet fighter aircraft, flying at supersonic speeds, it was believed desirable to extend detection of fighter targets to ranges of 10, 12 and possibly 15 miles. Since detection of these same targets by visual means was definitely limited, it followed that a search radar with these capabilities could have been employed if it were simple enough and had a simple presentation.

The proposed radar was basically a simple single-purpose 100 KW “X” band pulse type search set with one sweep range, 25 nm. Detection information including range and approximate target direction were simultaneously displayed to the pilot on a 5″ diameter high-intensity cathode ray tube indicator. With this information the pilot was able to fly his aircraft and track the target to a visual detection range. This was accomplished without target lock-on and automatic tracking circuitry was was used in contemporary systems such as the AN/APQ-41 and the AN/APG-37. Once visual contact was made the radar was used to supply target range information to the Mark 16 optical computing sight from which gunfire was directed. A receiver-transmitter modulator, antenna, indicator synchronizer, and control box were included in the proposed radar. The following is a brief itemized operational description of the system:
a) Controls—Operation was instigated by the pilot who had one primary control, an ON-OFF switch. Focus, brilliance and receiver gain controls were added so that the picture could be adjusted for optimum viewing. These latter controls could be set on the ground during pre-flight checks.
b) Antenna Scan Coverage—The search antenna, a paraboloid approximately 22″ in diameter, mounted in the aircraft’s nose section, revolved at a high rate of scan in a circular pattern about the airplane’s centerline covering a conical area of plus/minus 60° from this same center line. This coverage was accomplished by mechanical movement of the antenna as it spun in either a spiral or nodding manner.
c) Indicator Presentation—The cathode ray tube indicator picture which was used by the pilot for search and tracking purposes was a vertical type PPI display which revolved in synch with the antenna’s rotation. In other words, the fighter airplane was at the center of the scope and the sweep gave range and approximate elevation and azimuth position information of the target. This is further illustrated in Figure 14. Roman numeral I of Figure 14 shows how this presentation would have appeared, based on a sweep range of 25 nm. The earth’s radar return would have essentially formed an artificial horizon at the bottom of the scope and further given the pilot his approximate altitude and attitude above the earth’s surface. Reference marks showing range, as well as horizontal and vertical reference lines were etched on the face of the cathode ray tube. Targets that appeared above the horizontal line were those targets above the fighter and those which appeared to the right of the vertical etched line were to the right of the airplane and those that appeared on the left of this line were to its left. Thus, if a target was detected as shown in Roman numeral II, it was up and to the right at a range of 15 miles. The pilot’s next move was to fly in the general direction of this target as shown in illustration III. When the target was approximately on the airplane’s center line it broke into a circle as shown in illustration IV. The circle resulted from the fact that the antenna beam was illuminating the target in all of its axial rotational positions. The pilot then flew the presentation keeping a circle on the scope at all times. This meant that he was tracking the target accurately. As the range reduced, the circle shrank in size until he could visually see the target. At this point, the radar could be locked on to the target in range only and would supply this range information to the Mark 16 sight. From this point to the kill, tracking and subsequent gunfire was identical to the normal operation with only a range radar. It was believed to be highly desirable to develop such a fire control system to improve the utility and target acquisition range of the day fighter airplane. If the principles of operation outlined above were strictly adhered to and no additional requirements were imposed on the radar system, Lockheed believed that a truly simple system could have been devised.

Note that the document doesn't name the 'Alternate Fire Control System' (the primary one was the Mark 16 sight coupled to the AN/APG-34 ranging radar), but obviously its desrciption fits to the AN/ASG-14 radar. The Figure 14 indicated in the text is below.

Piotr

 

[marcox43]

I'm just reading "History of Air Defense Weapons 1946-1962" by Richard F. McMullen (http://www.northcom.mil/FOIA/docs/History of Air Defense Weapons, 1946-1962.pdf).

On page 316 of the PDF the author says with respect to the F-104A's radar:



Does anybody have any information on how the radar of the F-104A actually worked?

Piotr

Do you have the pdf somewhere? the link is down...

 

[yahya]

Check here:

Index of /afhracollection/ADC Command Historical Studies (Select 1-40)