Wednesday, July 15, 2015

A Mysterious LM CUDA Missile Update

Just gets more interesting as time goes on...

Major Hat Tip to Marauder for finding the relevant AFIT Technical thesis and passing it along

Regular readers may remember one of my most popular posts on LM’s CUDA missile concept. In that post, I hypothesized some about the CUDA’s weight and resultant performance by using a comparative analysis of what little was known about the CUDA and existing missiles with known physical characteristics. Key assumptions were that the same kind of propellant characteristics and relative scaling of the different components of existing missiles would apply to the CUDA.

Based upon a recent AFIT paper I no longer believe that approach is sufficient.

Employment of a CUDA missile ‘concept’ was used in a thesis written by Army Major Casey D. Connor, and published earlier this year. In his paper “AGENT-BASED MODELING METHODOLOGY FOR ANALYZING WEAPONS SYSTEMS”, Major Connor modeled and examined the relative effectiveness of different missile loadout combinations for a very specific A2A mission using two methods of attack: 'straight-in' and ‘pincer’.
The paper was exploratory in nature, and there’s not enough in the paper to come to any more conclusions than Major Connor did -- but I’m sure someone will read more ‘findings’ into it than he did. In fact, I'd expect 'some' to leap to all kinds of ‘conclusions’ about a lot of different sub-topics because the paper really does raise some very interesting questions that someone else will probably/hopefully pick up and follow-up on going forward.
The value of the paper to us in this instance is that it gives us an indication of some key performance—shall we say—“possibilities” for a CUDA-like weapon system. The paper uses the terms CUDA-like and SACM (Small Advanced Capability Missile) interchangeably. Given the rumblings on the web and in aero media since the CUDA concept’s existence went public, the relationship of the CUDA (a Lockheed Martin concept) to SACM (the programmatic objective of CUDA) is now better known. No surprises there.

What is Surprising?

What IS surprising (to me at least) are the characteristics used for the CUDA/SACM in Major Connor’s thesis. Specifically, Connor provides the CUDA/SACM weight used in his simulations as 49Kg (108 lbs). This has HUGE implications. 

If by my original speculation where I extrapolated known data about existing technology, I had arrived at a weight estimate that was 45.5 lbs higher (153.5 lbs) than the 108lb weight Connor uses, then it almost certainly speaks of significantly more advanced/miniaturized technology than simply scaling down 'more of the same' from existing systems.

I had toyed with putting a wedge in my original estimate for a reverse-weight spiral (less structural weight is needed the lower the non-structural weight), but thought that would have been pushing all the ‘estimating’ a little too far. As it turns out I would have come closer, but still nowhere near a mere 108 lbs for a CUDA weight estimate by my using current weapons for baseline info. I think now that ‘Next generation’ guidance, control, structure, and maybe  propulsion technology breakthroughs almost certainly permeate that CUDA/SACM design concept. As the scaling of RM propellant weight probably still applies (harder to make lighter propellant than other components), I don't think there's much weight change per cubic inch of volume there. But even so, this new lower weight could potentially drive the CUDA/CACM higher in the ‘Delta V’ performance than what I had previously estimated.

What Changed?

If only the weight is lower, with the other factors such as the ratio between pre-launch and expended rocket motor weights, and propellant/rocket factors, etc., then the CUDA potential top speed would not necessarily be higher than my first estimate (~24% higher than AMRAAM using existing missiles as guides). But I don’t think that at this new lighter weight, the same ratio CAN still hold true: a larger percentage of the total CUDA/SACM weight is now more likely found in the rocket motor -- if only just because everything else got lighter.
This shift in weight contribution, in turn, would mean a larger percentage of pre-launch weight is propellant that will be expended in acceleration. The scope of the impact of such a change is unknown, but here is a parametric exploration of the impact of various possible RM weight ratios from no change (54.53%) and up to a little more than 5% increase (60%):
What if the CUDA has a higher percentage of propellant weight than the AMRAAM?
(updated verbiage for more clarity less obfuscation)
As you can see, very little increases in the ratio of propellant weight to total weight yields significantly higher potential Delta V that could be tapped into to:

  1. increase range, 
  2. enable shaping complex flyouts, and/or 
  3. increase end-game dynamics. 
That this improved performance is likely a ‘truism’ in the CUDA/SACM design concept is reflected in Major Connor’s findings.

Connor’s modeling of the engagements he selected resulted in outcomes where the ‘pure’ CUDA/SACM loadout successfully engaging the RED AIR targets at significantly greater distances (32%-38% greater, depending on attack method used) than the Medium Range Missile Model (AMRAAM-basis) used (see Fig. 43 below from the source). That kind of range advantage would be consistent with a higher Delta V for the CUDA/SACM weapon.

[Note: Read the paper for information on the mixed loads of a short range missile (AIM-9X ‘like’), medium range missile (MRM) and the CUDA/SACM weapons]

The higher performance of the CUDA/SACM also shows up in the higher 'effectiveness' ratings of the pure CUDA/SACM loadout over the pure MRM loadout. As Figure 42 from the paper below illustrates, the pure CUDA/SACM missile loadout kills targets at better than a 2 to 1 advantage over the MRM’s kill rate as well as doing so at ranges farther than the MRM. 

This increased effectiveness suggests perhaps an even better end-game kinematic CUDA/SACM design performance than the MRMs due to a higher percentage of propellant design weight, working with the hit-to-kill Attitude Control Motors (ACMs) in the front-end. 

Connor’s focus in the paper isn’t on getting into the nuances of the CUDA/SACM’s capabilities, but the higher performance of the CUDA concept indicated by the data is supported by his observations within the text as well:
The main characteristics of the new missile technology examined in our research include hit-to-kill technology in which the missile uses a kinetic warhead to attack the target, agility in that the missile’s guidance, propulsion, and control surfaces allow it to maneuver more flexibly towards a target, and a smaller size allowing each fighter to carry more missiles. These new weapons have the potential for dramatically changing the range of possible tactics and mission roles allowed. (p.1)
Tactics best suited to the new missile are ones that maintain BVR to take advantage of the increased engagement ranges and possibly combined tactics that allow the flexible maneuvering characteristics of the new missiles to engage enemy aircraft at angles that the enemy aircraft will be unable to counter. (p.102)
There’s a lot of other ‘food for thought’ on many air combat topics in the paper. Connor was meticulous in documenting what he could of the methodology that he used including the limitations, ground-rules and assumptions. There’s also some excellent sources listed for further reading in the list of references.

Time will tell if the SACM concept will be developed into a full-up weapon system. But I must say that if it doesn’t go forward in some iteration or another I will be even more surprised than I have been so far in following the CUDA/SACM story.

Note: minor edits for readability and clarity made 16 July @ 1945 CST.


Antonio said...
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Antonio said...

So first time commenting on your blog, and I have to say that your site is one of the few that I go to for F-35 info. I noticed that Sol was talking b.s. again, wanted to see if you had any comments on any of his "points" (if they can even be called that).

SMSgt Mac said...
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SMSgt Mac said...

Hi Antonio,
Heh. Too funny. This go-around, I specifically avoided any mention of what this could mean outside pure missile performance possibilities, including utility to LO-enabled fighters of any kind, much less just the F-35. I wanted to focus on the new data point and implications for the missile design capabilities.
I don't know about anyone else, but when I read Connor's study, the first thing that struck me was how his scenarios and GR&As went out of their way to avoid/minimize non-missile factors (while keeping RED AIR numerical superiority). Opponents in his scenarios could have just as easily all been flying F-15s, as they were all modeled to be 'F-15 like'. The potential advantages of the CUDA/SACM concept might just be greater for keeping 4th Gen fighters alive at the edges of a fight as for making LO airplanes more effective. Who knows?
Thanks for coming by, and for the kind words.

TOMARI IV said...

Connor's results cannot be relied upon at least in so far as tactics are concerned because of the simplistic assumptions made. For example he finds pincer tactics to be inferior to a straight run attacks, while in fact the exact opposite holds true. Further straight run attacks will only be used by the F-35. Fourth gen jets do not use them (unless the target is unaware, a 4th gen fighter will offset then point-and-shoot and then offset again). Target reactions are not modeled and it may well be impossible to model them and this is the reason why decisions cannot be made on the basis of simulations such as this. You need to put some flight time in the Nevada ranges,