About the AIM-54C

[CarbonFox]

Two questions:

 

 

Did the AIM-54C ever get both the Mk.47 and Mk.60 rocket motors or did it just receive the smokeless Mk.47?

 

 

Will the improved AIM-54C ECCM (AIM-54C+) be developed at some point for the Tomcat?

[Quid]

According to Navy Training System Plan documents on the AIM-54 from 1997, by that point the AIM-54A, C, and C ECCM/Sealed used the Mk.47 MOD 1 motor. It doesn't mention the Mk.60 for propulsion. As it stands, I have a few books which include the same line from F.B. Newman from Hughes stating the very vague: "the AIM-54C was the model that had everything they'd ever wanted in it - a higher thrust motor, an improved warhead, and an improved fuse."

 

The problem is: what is meant by "higher thrust" - it's utterly ambiguous. Other segments of the missile have been discussed with specifics (e.g., the AIM-54C had a 25g limit), or in at least a descriptive (e.g., the DSU-28C/B fuse allowed the AIM-54C to properly range/fuse/detonate against a high-speed cruise missile in a steep, high-angle, high-velocity dive which the AIM-54A's fuse could not reliably do), but the Mk47 MOD1 was "higher thrust" than the MOD 0 of the 1970s doesn't really say anything meaningful, unfortunately.

 

EDIT: Further ambiguity is sources from the 1980s which list a general "Rocketdyne Mk.47 or Aerojet Mk.60" rocket motor for all variants of the AIM-54 that they list.

Edited August 14, 2020 by Quid

[Southernbear]

"the AIM-54C was the model that had everything they'd ever wanted in it - a higher thrust motor, an improved warhead, and an improved fuse."

 

My understanding was the AIM-54C was in response to the Iranian issue, with A model guidance being analog they needed to switch to a digital because their analog seekers were assumed to be compromised by Soviet intelligence and they needed a larger frequency bandwidth to make sure the Soviets and or Iranians couldn't spoof the missile. In turn this gave it much better ECCM.

 

However. From reading what I could. As well as a comment posted on a pilot forum from a mechanic/designer/technician for the AIM-54 (yeah I know take it with a pound of salt ofc) that the AIM-54C has essentially the same level of guidance as the A and that due to it being heavier and the logic pathways being more complicated it actually made it *less* accurate then the simplistic AIM-54As.

 

Of course this all could be not true but this is what I've found after digging around

[near_blind]

 

However. From reading what I could. As well as a comment posted on a pilot forum from a mechanic/designer/technician for the AIM-54 (yeah I know take it with a pound of salt ofc) that the AIM-54C has essentially the same level of guidance as the A and that due to it being heavier and the logic pathways being more complicated it actually made it *less* accurate then the simplistic AIM-54As.

 

Of course this all could be not true but this is what I've found after digging around

 

I'd be curious to read that, as it runs contrary to just about every official document or public interview I've seen. It'd be like someone saying the AIM-7E is superior to an AIM-7M because analogue is simpler.

[Quid]

My understanding was the AIM-54C was in response to the Iranian issue, with A model guidance being analog they needed to switch to a digital because their analog seekers were assumed to be compromised by Soviet intelligence and they needed a larger frequency bandwidth to make sure the Soviets and or Iranians couldn't spoof the missile. In turn this gave it much better ECCM.

 

However. From reading what I could. As well as a comment posted on a pilot forum from a mechanic/designer/technician for the AIM-54 (yeah I know take it with a pound of salt ofc) that the AIM-54C has essentially the same level of guidance as the A and that due to it being heavier and the logic pathways being more complicated it actually made it *less* accurate then the simplistic AIM-54As.

 

Of course this all could be not true but this is what I've found after digging around

 

I don't think that's correct. Work on the AIM-54C started in October 1976[1], three years before the revolution in Iran. The first 15 pre-production rounds were delivered in early 1980 for initial flight testing and firing. First launch of a pre-production AIM-54C using solid-state electronics was 2 June 1980 against a QF-4, which was a successful intercept[2]. The initial production batch of 30 was delivered to the US Navy 27 October 1981 with full production starting in 1982[3]. The decision to go with solid-state electronics was to improve reliability, ECCM capability, reduce internal heat generation to eliminate the complex cooling loops needed for the A and B models, and correct the gap in performance noted with the AIM-54A's ability to intercept a high-speed diving cruise missile. This wasn't some quick-reaction acquisition in response to the revolution, it was deliberately developed over years. Could the revolution have sped up the timelines to get the missile into service earlier? Possibly, but three years of development had already been undertaken by that point, so it wasn't the cause.

 

I also don't really buy the second part. The C model was more maneuverable, fully digital (to include transmitter/receiver, programmable digital signal processor, autopilot and inertial reference unit), with an improved fuse, improved target discrimination, range discrimination, reduced drift, and better performance into beam attacks.[5],[6] That tells me the missile would not have had an arbitrary reduction in accuracy from the former, analog model. The weight differential was not substantial for a missile that size; only around 30 pounds.

 

References:

1. Tony Holmes, Grumman F-14 Tomcat All Models 1970-2006 (UK: Haynes Publishing, 2018 ), 41.

2. Bill Sweetman et al., The Great Book of Modern Warplanes, (New York: Portland House, 1987), 634.

3. Ibid.

4. Jon Lake (ed.), Grumman F-14 Tomcat Shipborne Superfighter (UK: Aerospace Publishing London, 1996), 86-87.

5. Ibid., 87.

6. Draft Navy Training System Plan for the AIM-54 Phoenix Missile, June 1997, I-3.

Edited August 15, 2020 by Quid
Formatting

[Bearfoot]

[TL;DR -- the C was an improvement over the A in many respects, and one of the major practical goals of this improvement was to take on cruise missiles. There is no documentation to suggest that it was a worse performer in any respect to the A.]

 

• 
   
  
• The first part of @Southernbear's post (the move to digital avionics as response to the Iranian issue) is incorrect, but not entirely off base. As given by the reference linked to below: "An increased emphasis was placed on the missile [AIM-54C development] after the Iranian revolution to minimize usefuell of any information about the AIM-54A ..." So the C model development was already in the works, independent of anything going on with Iran, and while there was increased motivation for it, it was not in any way a response to Iran.
   
  
• The most specific statement I've seen of how the C is improved over the A is the ability to take on smaller targets, in particular cruise missiles (see attached excerpts).
   
  
• The second part @Southerber's post is, well, much more difficult to accept/justify/defend. There is absolutely no documentation historical or otherwise that I've seen has indicated that the C was a regression in any level or measure of performance.
   
  
• The biggest problems I've read about with the Phoenix in US service is (initially, until procedures were changed) insufficient training for the ordnance crews, rather than design issues. I've attached screenshots of sources. I do remember watching some documentary where the crew had no idea to how to put the fins on the missile and we saw them going through the manual to try and figure it out. I thought it was very odd at the time. Unfortunately, I cannot remember where I saw that, nor of course should this be taken as reflective of the more general situation with the USN!
   
  

 

Of course, all this could be wrong. Would be happy to learn from folks who know better, if so.

Edited August 15, 2020 by Bearfoot

[Southernbear]

Yeah I came across it when trying to look for, or rather challenge, a friend's statement that was that the AIM-54A missiles could not maneuver or could not maneuver very well while the rocket motor was firing and that the AIM-54C could and thus would make a MUCH better WVR weapon if you messed up and only had a target at <20nmi and didn't have any Sparrows or AIM-9s.

 

Ofc after even the smallest testing within DCS I found both to be able to guide while burning but I took my search to google as DCS sometimes isn't correct and with HB waiting on ED so they can put in their new Missile API you never know so I went looking and found the other info above...neither are probably true but thats how I got there

[Southernbear]

Ah I found it

 

"AIM-54C. When the Shah's regime fell into the hands of the Ayatollah, the DOD claimed the missile was "Iranian Compromised" because many missiles were examined in KGB labs and determined the missiles transmitter frequencies and first and second intermediate frequencies used for processing. Thus, there was a rush to implement a "digital version" which was named the AIM-54C. 54C employed modern high speed bit slice microprocessor with reprogrammable memory and digital filters and digital signal processing. This design allowed the missile to operate over a wider range of frequencies, sniff the RF environment, and pick frequencies not jammed and well as implementing more advance electronic countermeasures algorithms. The missile used linear frequency modulation which would allow the missile to know its range and range rate to target. Later version AIM-54C (ECCM/Sealed) missiles did not required the aircraft thermal coolant and could operate over a wider temp range. Because the 54C was more complex and new it did not achieve quite the success that the 54A did in term of probability of kill but was still an effective weapon.

 

I'll look up my notes on the propulsion sections to see what the ifference in the Rocketdyne solid propellant rocket motors were and their thrust ratings.

 

Hope this helps a little from an AIM-54C Test And Evaluation Engineer"

 

This statement above was found on the ED forum of all things but I very much remember finding this same thing almost word for word somewhere else so my guess is it was copy pasted from here. I don't necessarily believe it but its what I found when looking for how effective the AIM-54 was going to be in WVR combat

 

https://forums.eagle.ru/showthread.php?p=4203421 here is the thread, its pretty old and mostly full of people that complained about the F-14 being "too good" when it was first release, the paragraph in question was posted by Beyond_the_Infinite, apparently

[Southernbear]

Allow me to reiterate as well, I am not questioning the AIM-54's ability to shoot down fighters or do what it was designed for and how well and how far it can do that. I am simply asking PARTICULARLY since the AIM-54A Mk 60 has much more range then, if the AIM-54C guides about as well as the AIM-54A Mk 60 then with DCS the Mk 60 would just be simply better.

[Quid]

So, the AIM-54C started development before the Iranian Revolution but was accelerated in response to assessed/potential compromise - it was not started because of it. The statement about "Because the 54C was more complex and new it did not achieve quite the success that the 54A did in terms of probability of kill" is vague. That doesn't say "it was less maneuverable" (it wasn't, based on published figures) nor does it say anything about its physical performance. That could be a comment about the fact that several were fired in anger and missed on account of different reasons as compared to Iran's claimed victories with the 54A, or it could be a comment about test range performance, or it could be something someone said during a conversation at a bar.

 

As it stands, this has become a rabbit-hole; I don't think any of us has adequately answered OP's original question, other than to say after a certain point (at least the mid-1990s), the missile had a Mk.47 MOD 1 motor in it and not a Mk.60. That said, if the sources are reliable and if the Aerojet contract ended in 1978 for the Mk.60, I'm guessing it wouldn't have been used for the AIM-54C.

Edited August 18, 2020 by Quid
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