AN/APG-37 and MG-4 size and weight

[msxyz]

I was wondering how much these two pieces of electronic equipment contributed to the growth in weight of the F-86D/K over the F-86.

Does anybody has some data? Also, I understand the MG-4 fire control system what somewhat less advanced than the Huges E-4 that was exclusive to the US F-86D. What were the main differences between the two?

 

[Maury Markowitz]

The Dog was originally supposed to mount the E-1, also used in other aircraft like the F-94 and F-89. In this case, it would be mounted in a wing-suspended pod, as was the case for any number of WWII aircraft, especially Navy. However, for the high-speed role, there was concern that the drag would affect performance too much, so Hughes proposed re-packaging the E-1 into a smaller form that would fit in the nose. This became the E-2. The main difference, aside from the packaging, was the addition of an artificial horizon line so the pilot could fly heads-down.

The E-2 was never delivered, instead, the USAF decided future interceptors would be fire air-to-air rockets, so it was modified for this role as the E-3. The main difference between the E-3 and E-2 was the addition of a lead-computing calculator to put the aircraft at some distance behind the target rather than using a simple collision-course, and to add range cueing to the display. This allowed it to be used in completely blind engagements - this was not useful for the E-1 as the guns would be fired within visual range anyway. I'm not 100% clear what the difference between the E-3 and E-4 were, they appear to have identical functionality.

The E-series continued until the E-9, which was the first to differ significantly, moving to the APA-84 computer. This became the MG series, which in turn became MA-1. Unfortunately, the article I have doesn't have weights except for the MA-1, which was 2520 lbs. This was significantly more advanced than the E-series, including autopilot guidance, datalink to SAGE, firing modes for the Falcon, and more advanced intercept imagery, but it's unclear what items are part of that weight number.

Overall I would say it's safe to say that the entire system, including the radar, was on the order of 1,500 to 2,000 lbs.

 

[msxyz]

Thanks for the reply. Knowing the weight of the engine and other equipment I also came to a similar conclusion but I was a bit perplexed by the result. In 1945 US had small airborne radars for the TMB Avenger and the P-38 Lightning that weighted around 250lb (AN/APS-4/6). Considering the small dish antenna and its range, the radar mounted on the F-86K must have been similar in size so the rest of the weight must have come from the guidance package.

 

[Maury Markowitz]

Indeed. There were 200 boxes in total in the case of the MA-1, so there's that.

 

[P-STICKNEY]

The Dog was originally supposed to mount the E-1, also used in other aircraft like the F-94 and F-89. In this case, it would be mounted in a wing-suspended pod, as was the case for any number of WWII aircraft, especially Navy. However, for the high-speed role, there was concern that the drag would affect performance too much, so Hughes proposed re-packaging the E-1 into a smaller form that would fit in the nose. This became the E-2. The main difference, aside from the packaging, was the addition of an artificial horizon line so the pilot could fly heads-down.

The E-2 was never delivered, instead, the USAF decided future interceptors would be fire air-to-air rockets, so it was modified for this role as the E-3. The main difference between the E-3 and E-2 was the addition of a lead-computing calculator to put the aircraft at some distance behind the target rather than using a simple collision-course, and to add range cueing to the display. This allowed it to be used in completely blind engagements - this was not useful for the E-1 as the guns would be fired within visual range anyway. I'm not 100% clear what the difference between the E-3 and E-4 were, they appear to have identical functionality.

The E-series continued until the E-9, which was the first to differ significantly, moving to the APA-84 computer. This became the MG series, which in turn became MA-1. Unfortunately, the article I have doesn't have weights except for the MA-1, which was 2520 lbs. This was significantly more advanced than the E-series, including autopilot guidance, datalink to SAGE, firing modes for the Falcon, and more advanced intercept imagery, but it's unclear what items are part of that weight number.

Overall I would say it's safe to say that the entire system, including the radar, was on the order of 1,500 to 2,000 lbs.

I think that may not be quite correct - The E-3 and E-4 calculated a lead-collision (Constant Bearing) course to the rocket release point - Lead Pursuit, which is what is used for a guns solution, is a Bad Idea when you're trying to make a pass at a bomber which is nearly as fast as, or is faster than your interceptor - it invariably puts your fighter directly behind the bomber, in full view of, and in an easy shot for his tail guns. Also, since bombers of the 1950s generally had more maneuver margin than a transonic jet fighter, a turn by the bomber as the fighter is close to firing range means that the fighter can't turn enough to pull lead on the target. Add in the problems of converting a head-on intercept into a stern pass that does not require a long tail chase, and Lead Pursuit with guns or rockets isn't effective.
I've been searching through my archives, and I don't have the Weight and Balance summaries for an F-86D/L or a K.
I can throw in this - the early model F-86D-1s that were converted to TF-86Ds and used as safety chase aircraft at Tyndall and Yuma were 750 lbs lighter, but also had ballast added to keep the Center of Gravity in the right place. The total system weight was probably on the order of 900-1200#, but that's only a guess.
The difference between the E-3 and E-4 systems was that the E-3 used the 50 KW AN/APG-36 radar, (F-86D-1 only), and the E-4 used the AN/APG-37 at 250 KW.

 

[P-STICKNEY]

Indeed. There were 200 boxes in total in the case of the MA-1, so there's that.

I've been able to dig up some decent numbers - Here are weights for the various fire control systems, from the Standard Missile Characteristics of the GAR-1 (Radar Falcon), FAR-2 (IR Falcon, GAR-11 (Fat Falcon / Nuclear Falcon), and AIM-4E

Aircraft Fire Control System FCS Weight (Radar/Computer) Missile Auxiliaries Weight Weapons
F-89H MG-12 907 lbs 343 lbs FFARs, GAR-1/AIM-4A GAR-2 (AIM-4C)
F-89J MG-12 (IR Only) 669 lbs 152 lbs FFARs, GAR-2, MB-1 (Genie)
F-102A MG-10 1200 lbs 234 lbs FFARs, GAR-1, GAR-2, GAR-11
F-101B MG-13 831 lbs 232 lbs GAR-2. MB-1 (Note - early installations were 3 GAR-1 + 3 GAR-2 on opposite sides of the rotating armament pallet, this was prototyped only. Service aircraft carried 2 GAR-2 + 2 MB-1
F-106A MA-1 2017 lbs 145 lbs AIM-4E, AIM-4F, GAR-2
Genie

Now for the Various Dogship Sabres - we'll need to do some inference here -
It's safe to assume that the E-4 FCS would weigh about the same as the system on the F-89H and J - since we know that the radarless D models (TF-86D) weight 760 lbs less, but included ballast, let's go with 900 lbs.

So - what was the penalty for SAGE compatibility? The equipment lists in the Flight Manuals list the Data Link Receiver/Interface as the only difference.
F-86D Empty Weight: 13518 lbs
F-86L Empty Weight 13822 lbs
So, a difference of 309 lbs - easy, right? Well, no - the F-86L upgrade also included the slatted 6-3 wing, with 24" more span.
That ends up adding 240 lbs. So the added weight of the Data Link is 69 lbs or so.
So - the F-86K, with the same radar, but a simplified computer (Remember that this is all analog, tubes and gears and cams)
tips the scales at 13367 lbs, so the computer has had about 150 lbs of simplification.

 

[Larcrivereagle]

The E-series continued until the E-9, which was the first to differ significantly, moving to the APA-84 computer. This became the MG series, which in turn became MA-1. Unfortunately, the article I have doesn't have weights except for the MA-1, which was 2520 lbs. This was significantly more advanced than the E-series, including autopilot guidance, datalink to SAGE, firing modes for the Falcon, and more advanced intercept imagery, but it's unclear what items are part of that weight number.

I've only now discovered that the E-10 fire control system did exist, apparently it's the APG-37 radar used by the F2H-4 Banshee/Banjo

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