E-2 Hawkeye avionics on E-1B Tracer airframe?

[Pioneer]

With the ever advancing speed of electronic technology, predominantly spurred on by military application, came the ever steady miniaturisation of electronics.

My question/topic to the forum pertains to whether the likes of the electronics/systems (APS-125 radar and associated electronics, computers systems) of the USN ‘OS-139’ Carrier-based AEW aircraft program, which lead to the Grumman YW2F-1 (E-2A Hawkeye), could have been incorporated 'into/on to' a modified Grumman E-1B Tracer variant, to create a smaller and cheaper E-1/E-2 hybrid AEW platform, to serve foreign/allied navies who operated smaller carriers than the US Navy, or aboard smaller US Navy carriers, which couldn’t operate the larger, heavier and more expensive Grumman E-2 Hawkeye? Or for that matter the hybrid Tracer could potentially give smaller air forces a cost achievable AEW platform?

Naturally, the Tracer’s radial engines would be replaced by ‘a then’ appropriate turboprop engine (pre-S-2T TurboTracker arrangement). This would not just give additional power for a lesser weight, it would undoubtedly give the hybrid a much improved high-altitude performance, which is critical to an AEW platform, as well as power for onboard electronics.

The following considerations/questions are what comes to mind:

- Being conscious of the inherent difficulties of inadequate cooling in the closely packed avionics compartment, by potentially utilising the operational gained experience of the ironed-out bugs E-2B Hawkeye variant - which replaced the unreliable rotary drum computer with the digital Litton L-304 computer system’
- Refurbishing retired USN Grumman E-1B, to serve as new hybrid AEW platform;
or
- Using existing surplus Grumman C-1 Trader’s fuselage’s (of which 87 samples were built), and incorporating an 18-nch (or more if required and feasible) stretch of the E-1B Tracer configuration, to serve as new hybrid AEW platform
- Would the APS-125 radar dish be too large for the E-1 hybrid? If so would it be feasible to cut-down the diameter of the ????? antenna arrangement, so as to make it more feasible? (understanding and excepting, by doing so it would undoubtedly effect the ?????’s performance!). Either way, the large and draggy the radome arrangement of the original Hazeltine AN/APS-82 radar would need to be replaced with a more aerodynamic arrangement!
- Specifically, aware of internal fuselage space and room and functionality of ‘Radar/Intercept Controllers’ (The original E-1B Tracer having two Radar/Intercept Controllers, and the E-2 Hawkeye having four Radar/Intercept Controllers, would it be feasible, as in the case of the Lockheed P-3 Orion/Lockheed S-3 Viking to operate the APS-125 radar with two Radar/Intercept Controllers?

P.S. Does anyone have a comparison drawing of the E-1 Tracer and the E-2 Hawkeye, so as to physically see differences of the two in size?

I look forward to your feedback and input!

Regards
Pioneer

 

[Arjen]

Does anyone have a comparison drawing of the E-1 Tracer and the E-2 Hawkeye, so as to physically see differences of the two in size?

3-views from 'Grumman Aircraft since 1919' by René J Francillon, Putnam 1989.
The lower right-hand corner shows two scale-bars ...
- upper bar from the original E-1B drawing
- lower bar from the original E-2C drawing
... to indicate to what extent modifying the E-2C drawing to the E-1B drawing's scale was succesful.

 

[Scott Kenny]

3-views from 'Grumman Aircraft since 1919' by René J Francillon, Putnam 1989.
The lower right-hand corner shows two scale-bars ...
- upper bar from the original E-1B drawing
- lower bar from the original E-2C drawing
... to indicate to what extent modifying the E-2C drawing to the E-1B drawing's scale was succesful.

Dimensionally it looks like you could stick the E-2 radome onto an E-1, it looks like there's enough space between the folded wings on the Tracer to fit the E2 radome. Even though the distance between wing folds is less on the Tracer.

 

[BlackBat242]

Dimensionally it looks like you could stick the E-2 radome onto an E-1, it looks like there's enough space between the folded wings on the Tracer to fit the E2 radome. Even though the distance between wing folds is less on the Tracer.

Since in both aircraft the outer wings rotate down and aft to fold, the radome could even extend past the wing-fold with no problems.

 

[Scott Kenny]

Since in both aircraft the outer wings rotate down and aft to fold, the radome could even extend past the wing-fold with no problems.

Wasn't sure how far the upper edge of the folded wing was above the wing.

 

[BlackBat242]

Here is an E-2 with the radome in the flight (up) position:


And folded with radome up:



Here is an E-2 with wings folded and the radome lowered (the variable-height function was designed for the Midway class carriers with their low 17' 6" hangar height - after that class was decommissioned the radome was permanently locked up):

 

[Scott Kenny]

Here is an E-2 with wings folded and the radome lowered (the variable-height function was designed for the Midway class carriers with their low 17' 6" hangar height - after that class was decommissioned the radome was permanently locked up):


View attachment 711219

Thank you!

What was the Hangar height of the Foch and CdG?

 

[BlackBat242]

Clemenceau/Foch clear hangar height was 22' 7" (6.9 m). Freeboard at aft (deck-edge) aircraft elevator 24' (7.315 m).

This is what I have:


A couple pics of hawkeyes in CdG's hangar (the second is a bit hard to see, but look near the far end for the radome):

 

[Scott Kenny]

Clemenceau/Foch clear hangar height was 22' 7" (6.9 m). Freeboard at aft (deck-edge) aircraft elevator 24' (7.315 m).

This is what I have:
View attachment 711279

Awesome, thank you again!


So it looks like a Super Tracer (E-1 with E-2 radar set) would have been beyond possible. I guess the only real issue would have been cooling the new radar.

 

[Arjen]

During E-2 development, cooling the electronics inside the fuselage proved to be a major problem. Stuffing the same electronics into the smaller E-1 would have exacerbated the problem. Newer electronics generated less heat, but, at one point, the original E-2A was so unreliable that production was halted in 1965.

 

[BlackBat242]

During E-2 development, cooling the electronics inside the fuselage proved to be a major problem. Stuffing the same electronics into the smaller E-1 would have exacerbated the problem. Newer electronics generated less heat, but, at one point, the original E-2A was so unreliable that production was halted in 1965.

That was mostly due to the E-2A's rotary-drum computer, which had a miserable reliability record.

52 of the 59 E-2As were upgraded to E-2Bs, with the Litton L-304 digital computer replacing the rotary-drum, and some other avionics systems upgraded.

 

[Scott Kenny]

During E-2 development, cooling the electronics inside the fuselage proved to be a major problem. Stuffing the same electronics into the smaller E-1 would have exacerbated the problem. Newer electronics generated less heat, but, at one point, the original E-2A was so unreliable that production was halted in 1965.

RR Dart engines, the likely conversion for UK use in the 1960s, are a couple hundred horsepower more each, so could power some pretty big chillers.

 

[orlovsky]

Are these nrs roughly right?
Wright in E-1B: ~1.1 MW, with APS-82/20ft radome
Dart in Alizé: ~1.5 MW, later versions 2+ MW
T56 in E-2A: ~2.5 MW, with APS-96 and later (as E-2B) APS-120/24 ft radome
T56 in later versions: up to 3.9 MW (?), E-2C with various upgraded radar versions

So maybe later versions of the Dart would provide enough power to handle the "E-2B standard" - if you can fit the electronics into the E-1 fuselage.
Would you need a 3rd radar operator? Another demand on space.
Any ideas of how the internal volumes of the E-1 and E-2 compare? The E-2 is (empty/full) almost twice as heavy.

Costwise, with a small series and the E-2 equipment, I'd guess the improved Tracer will cost about as much as the comparable E-2.

 

[Scott Kenny]

Are these nrs roughly right?
Wright in E-1B: ~1.1 MW, with APS-82/20ft radome
Dart in Alizé: ~1.5 MW, later versions 2+ MW
T56 in E-2A: ~2.5 MW, with APS-96 and later (as E-2B) APS-120/24 ft radome
T56 in later versions: up to 3.9 MW (?), E-2C with various upgraded radar versions

So maybe later versions of the Dart would provide enough power to handle the "E-2B standard" - if you can fit the electronics into the E-1 fuselage.
Would you need a 3rd radar operator? Another demand on space.
Any ideas of how the internal volumes of the E-1 and E-2 compare? The E-2 is (empty/full) almost twice as heavy.

Costwise, with a small series and the E-2 equipment, I'd guess the improved Tracer will cost about as much as the comparable E-2.

What matters here is not total engine power, but how much electrical power they can be set up to generate.

 

[orlovsky]

Sure, but I could not find anything specific on electricity generation in the E-1/E-2. Just that the maximum power of the radars is usually 1 MW.

In loiter, even with the early E-2A/B, a good junk should go the generators, and the propulsion advantage of the lighter E-1B should not be that big. That's why the early Darts with 1.5 MW look a bit weak to me, but that could be way off.

 

[orlovsky]

After further search, I found that the E-2C has 2 "60/90 kva generators" producing 48/72 kw of electricity. This was upgraded to 150 kva for the E-2D.
I'm not sure that this is the total capacity or how much engine power is diverted to the generators, but yes, it looks like a rather small share.

Addendum: The weight of the E-2 mission specific equipment is given as 10k lbs.

Aircraft Carriers

In the post-1945 era, the aircraft carrier has remained a valued weapon despite the development of nuclear weapons, cruise and ballistic missiles, and highly capable submarines. At times, as in the early days of the Korean and Vietnam Wars and in the Falklands conflict, carriers alone could...

www.google.at

 

[Scott Kenny]

After further search, I found that the E-2C has 2 "60/90 kva generators" producing 48/72 kw of electricity. This was upgraded to 150 kva for the E-2D.
I'm not sure that this is the total capacity or how much engine power is diverted to the generators, but yes, it looks like a rather small share.

Generators are listed by output, and I suspect that each engine on the E-2C has two generators. One 60kva, one 90kva, 150kva total.

Addendum: The weight of the E-2 mission specific equipment is given as 10k lbs.

Aircraft Carriers

In the post-1945 era, the aircraft carrier has remained a valued weapon despite the development of nuclear weapons, cruise and ballistic missiles, and highly capable submarines. At times, as in the early days of the Korean and Vietnam Wars and in the Falklands conflict, carriers alone could...

www.google.at

Oh, that is an awesome find!

 

[orlovsky]

The nrs for the generators are murky. Searching https://www.google.com/search?q=E-2+hawkeye+"kva" I get for the E-2C to D change:

"Two 170/225-kVA units will replace the current 60/90-kVA generators"

Could also be the output settings, all talk about 2 generators per plane.

Weight is interesting. The E-1 was about 4000 lbs heavier than the C-1. If this is the "AEW weight", I don't think getting 10k lbs and the associated volume into the airframe is possible.

An improved E-1B would need a tailored electronics suite, but with the progress in electronics, 4000 lbs in 1980 might do what 10000 lbs did in 1970 (random years just for illustration).

I haven't found anything about a USN Tracer upgrade even at the study level. They wanted to get to an all E-2 fleet as fast as possible, and had no interest in an AEW plane that might give the Essexes some lease on life....

 

[Scott Kenny]

Weight is interesting. The E-1 was about 4000 lbs heavier than the C-1. If this is the "AEW weight", I don't think getting 10k lbs and the associated volume into the airframe is possible.

But remember that the C-1 could carry up to 8500lbs cargo.

Interesting, the RR Dart engine I suggested is the same weight as the R1820 radial, ~1200lbs. I was not expecting that and do not like it. The TPE331 they actually used on the Turbo Trackers is much lighter at 385lbs dry and would give us another 1600lbs to work with.

As is, the E-1 has a MTOW that is 2000lbs more than the C-1. Between more powerful engines and hopefully newer electronics, we should be able to stuff at least 6000lbs of AEW gear in one.

I haven't found anything about a USN Tracer upgrade even at the study level. They wanted to get to an all E-2 fleet as fast as possible, and had no interest in an AEW plane that might give the Essexes some lease on life....

Unfortunate, but makes sense. The Greyhound was really that much better, mostly due to the massive engine power increase.

 

[orlovsky]

But remember that the C-1 could carry up to 8500lbs cargo.

I'm afraid that's the payload as in the difference between empty and max, including fuel and pilot. Actual Cargo was 3500 lbs.

https://www.aahs-online.org/images/Navy_SAC/C-1A.pdf

Comparing the SACs, the E-1B also carried more fuel, ~4500 vs 3100 lbs.

As for the TPE331, if I got the right data:
The -14 had only ~900 kw. The -15 got to 1200kw, but is only available from 1988 on. The Dart is available from the beginning, and it's been used in naval aircraft.

 

[Scott Kenny]

As for the TPE331, if I got the right data:
The -14 had only ~900 kw. The -15 got to 1200kw, but is only available from 1988 on. The Dart is available from the beginning, and it's been used in naval aircraft.

I'm mostly not liking that it wasn't any lighter than the radial engine... The whole point of a turboprop is that the engine is much lighter for the same horsepower... *grumble, cuss*

 

[orlovsky]

The versions vary a lot. The wright -82wa weighs close to 1500 lbs: https://airandspace.si.edu/collecti...-model-r-1820-82wa/sova-nasm-1987-0115-ref155

The more powerful versions of the dart are ~1300 lbs, could not find the weight for the Mk21 in the Alizé.

So roughly
wright 1500 lbs, 1200 kw, length 1.2 m ?, diameter 1.4m ?
dart 1300 lbs, 1500 kw, length 2.48 m, diameter 0.96m
tpe331-15 400 lbs, 1200kw, length 1.2 m ?, diameter 0.53m ?

The dart has some weight advantage, but it's also quite long. Not sure how well it would fit.

 

[Yellow Palace]

Wright in E-1B: ~1.1 MW, with APS-82/20ft radome
Dart in Alizé: ~1.5 MW, later versions 2+ MW
T56 in E-2A: ~2.5 MW, with APS-96 and later (as E-2B) APS-120/24 ft radome
T56 in later versions: up to 3.9 MW (?), E-2C with various upgraded radar versions

After further search, I found that the E-2C has 2 "60/90 kva generators" producing 48/72 kw of electricity. This was upgraded to 150 kva for the E-2D.

Worth noting that the difference here - the generators have an order of magnitude less power than the radar - will be that the quoted radar figures are peak power output, while the generator figures are constant. Radars operate with pulsed transmission - high output for a short time, followed by a longer period of listening for returns - so the average power is considerably less than the peak power. A considerable part of the electronics needed for a radar is the capacitors and assorted gubbins needed to level out that power consumption!

 

[Scott Kenny]

The versions vary a lot. The wright -82wa weighs close to 1500 lbs: https://airandspace.si.edu/collecti...-model-r-1820-82wa/sova-nasm-1987-0115-ref155

The more powerful versions of the dart are ~1300 lbs, could not find the weight for the Mk21 in the Alizé.

So roughly
wright 1500 lbs, 1200 kw, length 1.2 m ?, diameter 1.4m ?
dart 1300 lbs, 1500 kw, length 2.48 m, diameter 0.96m
tpe331-15 400 lbs, 1200kw, length 1.2 m ?, diameter 0.53m ?

The dart has some weight advantage, but it's also quite long. Not sure how well it would fit.

It's not likely to be an issue, since
1) there's already a Dart/1820 swap that's been designed; and
2) we're adding weight forward of CG with the Darts and and weight aft of CG with the new radar, it's a wash.

The big thing Darts would do is push the props forward of the cockpit.

 

[orlovsky]

1) there's already a Dart/1820 swap that's been designed; and

Was that for a Tracker?

 

[Scott Kenny]

Was that for a Tracker?

Looks like DC3s, Turbo Trackers were a late development and got TPE331s.

But the install should be very close to the same from firewall forward on a Tracker versus the DC3. All the engineering and math has been done on how the Dart install shifts the engine CG forward.

 

[orlovsky]

Interesting. The large radome may cause special problems, but they should be solvable.

I'm still sceptical whether the 10k lbs of E-2 equipment can be squeezed into the E-1 of half the weight. Although the only alternative in naval aircraft would probably be the S-3...

 

[orlovsky]

I admit that I now have a certain fascination with the E-1/E-2 hybrid Traceye.

Could not find more on power requirements or weights, but on costs in the US defense appropriations hearings. In the 60s and early 70s the E-2B/C cost about 15 million $, the C-2A 4 million. So roughly 10 mln $ for radar, electronics.

In the early 80s the E-2C cost about 40 million $, the new C-2 tranche 20 million. Roughly 20 mln $ for radar, electronics.

So replacing the airframe with the E-1 won't save much and

Or for that matter the hybrid Tracer could potentially give smaller air forces a cost achievable AEW platform?

will not work on the financial side, leaving the technical problems aside.

But who would buy this anyway? UK or France.
For the US, the E-2A was designed for the essex class.
For France, it might just work from the Clems.
For the UK, Ark/Eagle will have problems with lift size and hangar heights; CVA-01 should work.

So if size is the problem, can you do additional folds, weight savings, size reductions on the E-2?

 

[Archibald]

I didn't put my grain of salt in this thread - and I don't know why. Here we go.
Searching Google books I've found that in the mid- 1960's the Aéronavale had clearly identified the E-1B as the only AEW that could fit the Clems. From what I've found, they considered a few E-1Bs in the 1960's (but no money) and again, twenty years later: in the late 1980's. That time they wanted to put a Thompson CSF radar on second-hand Tracker airframes - no idea if they thought about Tracers, which had been send to the boneyard by the USN in 1978.
Note that the french flying firemen - La Sécurité Civile - loves their Turbotrackers since at least 40 years. And yes, the Aéronavale noted that too.

 

[orlovsky]

E-1 or S-2+radar, both with turboprops, are the cheaper and simpler solutions, no doubt. Both should work easily from the Clems.

But if you want the E-2 performance you need something bigger. Starting from E-2A, 49k lbs launch, ~40k lbs landing, 56'4"
- catapult: wod mostly negative with the C-11, would work with BS5
- arrest: also wod slightly negative for mk-7 gear, should work with UK sourced mk13
- deck strength 44k lbs, maybe a bit too heavy. 33k lbs for landing, but the slow speed of the E-2 might help.
- hangar height: no problem
- lift size: too long for the forward lift, would have to shed 2ft [edit: the forward lift of the Clems is given as 17m or 17.4m long. From the drawings it is 17.4m, so the E-2A/B (not the longer C) would just fit with 17.17m]. Should fit on the deck edge lift.
- lift weight: 44k lbs maximum, so fully tanked it would be too heavy.
- size of landing area on Foch from middle to safety line is 12.5m, E-2 would need more (1.5-2.5m?) room or less wingspan
- arrestor pullout 70m; E-2 might just need some extra space as on CdG
- Maybe landing problems in higher sea states

So with a bit of F-4K style fiddling it might just fit. Of course, it would still be a royal pain on the small flight deck, even with just 2 in the air group.

Then there's this, not sure if the info is correct or what it means exactly: "A noter que du 18 au 28 juin 1991, des essais d'évaluation opérationnelle du Hawkeye (un E-2C de l'U.S.N.) ont lieu sur le porte-avions Clemenceau." http://www.ffaa.net/aircraft/hawkeye/hawkeye_fr.htm

 

[Scott Kenny]

I'm still sceptical whether the 10k lbs of E-2 equipment can be squeezed into the E-1 of half the weight. Although the only alternative in naval aircraft would probably be the S-3...

Could probably drop one operator station from the E-2's setup in the 1960s to save weight. Won't save all the weight, of course, but will save a good 1000lbs, probably. (crew plus 2x or 3x CRTs plus all their hardware)

If we're doing this in the 1980s, we have lighter engines available and can just data-link down to the ship with no air controllers in the E-1 at all. Or one guy in back to keep the radar and datalink working.

 

[Pioneer]

Wow, thanks gents for revisiting this thread and contributing further evaluation and thought. Some very interesting infomation and analogies which gives much food for thought.

Naturally, my whole notion was that of an affordable carrier and land-based AEW aircraft. Affordable in the sense that due to their replacement by the E-2 in the USN, numerous (88 x E-1 Tracer's were produced, I believe..) E-1's would be made available for smaller navies equipped with small to medium-sized carriers, as well as small air forces which would greatly benifit from a patrolling/loitering (E-1B - range of 1,665 km
(1,035 miles), with an endurance of almost seven hours) AEW aircraft like a modernised, turboprop-powered E-1T Turbo Tracer. Also affordable, when one considers the cost of purchasing, let alone flying and maintaining a Boeing E-3 Sentry.

P.S. Given the weight of the E-1, with the benifit of turboprop engine weight and additional power, does one think such a E-1T would be able to operate from a Majestic-class carrier?

Regards
Pioneer

 

[Scott Kenny]

Given the weight of the E-1, with the benifit of turboprop engine weight and additional power, does one think such a E-1T would be able to operate from a Majestic-class carrier?

Yes!

The Royal Netherlands Navy operated basic S2Fs off of their Majestic class, the Karel Doorman.

 

[Archibald]

The Tracker was a relatively small and light aircraft with piston engines, so pretty close from a WWII airplane, as far as carriers are concerned. Not surprised he could fly out smallish carriers.

 

[orlovsky]

Could probably drop one operator station from the E-2's setup in the 1960s to save weight. Won't save all the weight, of course, but will save a good 1000lbs, probably. (crew plus 2x or 3x CRTs plus all their hardware)

If we're doing this in the 1980s, we have lighter engines available and can just data-link down to the ship with no air controllers in the E-1 at all. Or one guy in back to keep the radar and datalink working.

The question is, how modular is the E-2 avionics set? Can you leave bits out and it works? Would be good for a lighter E-2 or an improved E-1B. I would not bet on it, the E-2C 0 group could not be upgraded to ( I think group II) without the cost of a brand new plane (said the navy, at least).

 

[orlovsky]

Naturally, my whole notion was that of an affordable carrier and land-based AEW aircraft. Affordable in the sense that due to their replacement by the E-2 in the USN, numerous (88 x E-1 Tracer's were produced, I believe..) E-1's would be made available for smaller navies equipped with small to medium-sized carriers, as well as small air forces which would greatly benifit from a patrolling/loitering (E-1B - range of 1,665 km
(1,035 miles), with an endurance of almost seven hours) AEW aircraft like a modernised, turboprop-powered E-1T Turbo Tracer. Also affordable, when one considers the cost of purchasing, let alone flying and maintaining a Boeing E-3 Sentry.

Affordable as E-1B, definately. 2 mln $ new, maybe 1 mln second hand, turboprops maybe a few 100thsd.

But the E-2 avionics package is probably 10 mln $ in the early 70s. So even if you can stuff it into the Tracer, it will cost almost as much as an E-2 (and that is the best case). Maybe just stick with the old radar and try to get as much computing power into the airframe as possible.

As for the majestics, apart from the dutch, the Australians and the Argentines flew S-2 from the Majestics. The E-1 is not much heavier and just slightly bigger; however, the E-1 with E-2 avionics would probably go above 30k lbs and this might run into problems.

 

[orlovsky]

Addendum: The weight of the E-2 mission specific equipment is given as 10k lbs.

Aircraft Carriers

In the post-1945 era, the aircraft carrier has remained a valued weapon despite the development of nuclear weapons, cruise and ballistic missiles, and highly capable submarines. At times, as in the early days of the Korean and Vietnam Wars and in the Falklands conflict, carriers alone could...

www.google.at

Now I'm getting a bit sceptical. As usual, a nr is thrown around, but the book does not give a source and does not say what it includes and for which version of a 60 year old model it is valid. It seems to relate to the initial model(s), but who knows where the nr came from.

All empty weight:
As stated, the E-1B weighs 4000 lbs more than the C-1.

The E-2A was 4000 lbs heavier than the C-2A.
The initial E-2C was 6000 lbs heavier than the C-2A.
The E-2C of the early 80s was 7000 lbs heavier than the C-2A (reprocured).

The C-2 has a wider fuselage and a ramp, no idea how much weight is attributable. Stronger structure maybe, too?
The E-2 has an extra ~1000 lbs comparing launch weight excluding fuel and freight, probably the 3 (4?) extra crew.

So for later versions we may get close, for early versions the C-2 would have to have put on a lot of weight to even out.

 

[Scott Kenny]

The question is, how modular is the E-2 avionics set? Can you leave bits out and it works? Would be good for a lighter E-2 or an improved E-1B. I would not bet on it, the E-2C 0 group could not be upgraded to ( I think group II) without the cost of a brand new plane (said the navy, at least).

I was talking about dropping a display set. You're deliberately forgoing some better air control abilities for weight.

 

[orlovsky]

I was talking about dropping a display set. You're deliberately forgoing some better air control abilities for weight.

Yes, I was just wondering whether you could drop other "modules" or whether this further weight reduction would mean a redesign of the whole electronics suite.

 

[orlovsky]

Continuing the weight mystery: The S-3 AEW would integrate the E-2C avionics and with extra fuel tanks be 7300 lbs heavier than the S-3A:

Source:

http://home.comcast.net/~wmiipms/NewsLetters/1994/WMIIPMS_09-1994_NL.pdf

As this includes ~4000 lbs of external fuel and an additional crew member, the weight gain would be ~3000 lbs.

For the ES-3A, 3000 lbs of ASW equipment would be deleted:

Air Force Magazine

www.google.at

So ~6000 lbs of AEW avionics. Of course just a rough guess, as all those numbers are fuzzy.