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.
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
- increase range,
- enable shaping complex flyouts, and/or
- increase end-game dynamics.
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.
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)And…
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.