“Fighter Aircraft” Design: Driven by Operational Requirements (Part 3)

With the world about to bear witness at the Paris Air Show (#PAS17) this week that the F-35 is NOT the 'pig' aircraft that the propagandist critics (all of whom have NO material knowledge of the F-35) have claimed, I decided it was time to finally publish this post and close out the series. All the contrived elaborate and ignorant ‘stories’ assembled from twisted factoids  that have surfaced over the years, are about to fall flat, and will trigger much denial, wailing and gnashing of teeth from those quarters.
Now is also an especially good time for me to close out the series because it will be a handy reference for later smacking down a piece of anti-JSF Dezinformatsia that surfaced (as a metaphorical rotting dead cetacean) this week.

Behold! O haters and doubters.....and weep.

Super-manueverability without Thrust Vectoring, Check...

And so we proceed…

The entire point of this series has been and is to illustrate that fighter design isn’t driven by opinions, whim, or fashion; nor is the implementation of it either the least bit capricious. To recap, Part 1 of this series was just an initial outline of what I intended to cover/accomplish overall. Part 2 was an extended ‘two-parts in one’ review of the evolution of fighter design requirements from the earliest days and up through the emergence of ‘supermaneuverability’. We reviewed the developments that influenced fighter designs up through to the ‘fourth-generation’ of fighters and we could even say included design trends that influenced the earliest aerodynamics of fifth generation design: the F-22.

This brings us up to the starting point for Part 3, still somewhat in the past, but not so far as to prevent us from getting to the present from there. In the introduction of this series, I had originally envisioned that in Part 3 we would:

..."break down a 1 vs. 1 air combat scenario into a high-level conceptual model of constituent phases and associated combatant states. Then we will apprise the F-35’s potential advantages and disadvantages”...

As it turns out, we can leverage one and a half decades of expertise from professionals to accomplish the first objective and do so in fewer words than I had initially planned. We will also use the same for framing the discussion to meet the second objective: quickly ‘apprising’ the “F-35’s potential advantages and disadvantages”. It should shock only those with less than a passing interest in, and/or superficial knowledge of the subject, that by the time the first Part 3 objective is met, the second objective will become largely self-evident.


“Aircraft Maneuverability” or “Agility” research probably reached its zenith (in the West anyway) with the extremely successful X-31 Enhanced Fighter Maneuverability Demonstrator program.

Before the X-31 even flew, it was already viewed as a key investigative tool for ‘applied agility’ research, and the only effort at the time to span all “applied” research areas of interest.

Figure 1. X-31 Spanned Applied Agility Research Interests

I was TDY to Edwards AFB for one program or another and we had just landed (it had to have been sometime in 1992 or January-ish 1993 at the latest) and while sitting on the ramp waiting for a crew van, we watched the X-31 return from a mission and work the pattern with its chase plane. The discussion, led by our own test pilots and flight test engineers, turned to wondering: Just how much any additional maneuverability that might come out of the X-31 program would actually translate into any REAL additional combat capability? This is a question of the same kind of ‘asymptotic limits’ that were addressed in Part 2.

As it turns out, we still can’t quantify an answer to that question because nothing about that time on up through to the present day was, or is, “static”. Changes and developments in all the other fighter aircraft capabilities and technologies kept evolving long after we hit peak ‘supermaneuverability’ with the X-31. But from Part 2 and what we are about to review, we can answer the question in general:

1) Maneuverability beyond the F-16/F-18 characteristics doesn’t really get you all that much more capability (effectiveness and survivability), and  

2) When costs involved are considered, there are cheaper/better ways to increase combat offensive capability and survivability than improving AoA, turn rates, or g-loads past the present state of the art.

We know these are the answers because those involved in fighter design and development have known them for a long time. From 1986 through at least 1995, the NATO member countries of France, Germany, the United Kingdom, and the United States collaborated on a major study1 to determine where future fighter design efforts should be targeted.

Note:  

While I’ve been too busy to engage in substantial posting for a lot of reasons, another reason this post was so long in coming is the open source data has been fickle. I first typed out about 4K words (longer than this post) I had put to electrons just to go over the gory details in the study we are about to discuss. But after all that work trying to do justice to the contents of the study I found a copy of the original without a paywall in place. I slashed what I had written to leverage the source without saving the earlier version. Then the source disappeared again. If access reappears, I'll link to it.

The study had two major objectives:

• Through analysis and simulation, determine whether supermaneuverability is operationally useful in future air combat scenarios.  

• If operationally useful and technically feasible, determine the practical limits of supermaneuverability and full envelope agility.

The context of the study was obviously about the benefits of supermaneuverability in WVR combat. The authors referred to it as “Close In Combat” (CIC), of which choosing to engage in a turning fight is only one possibility. After all there’s not much point in doing a Danse Macabre if there’s no opponent within visual range to ‘appreciate’ it.

The study participants used the following definitions:

“Supermaneuverability is defined as very high levels of maneuverability and agility throughout the flight envelope of a fighter aircraft, especially beyond maximum lift.”  

“Agility is defined as the ability to change states rapidly with precision.”   

“Full envelope agility contains airframe, missile, and avionics attributes.”

It is important to observe here the recognition by the actual “experts” involved that the broadest definition of agility was important going in to the study. The definition of 'weapon system agility'  has become a somewhat standard one:

Figure 2. Weapon System Agility = Total Agility

(See also my backgrounder on modern Energy-Maneuverability,)

The study’s ‘statement’ of purpose was:

Previous analyses and manned simulations for close-in-combat (CIC), primarily emphasizing 1 v. 1, have indicated substantial improvements in air combat effectiveness when supermaneuverability (in particular, post-stall technology) was incorporated in advanced fighter designs. Recognizing that air combat scenarios are likely characterized by rapid transition from beyond-visual-range (BVR) to CIC involving multiple aircraft, the effect of supermaneuverability technologies on the outcome of this type of engagement needs to be determined.

This multi-national NATO-sponsored study began with manned simulation at Industrieanlagen-Betriebsgesellschaft (iABG), involving two piloted aircraft and three computer generated aircraft. Four pilots were trained on the baseline post-stall aircraft including avionics, weapons, and scenarios. After the training phase, the pilots jointly determined possible starting conditions (geometry, speed, weight, weapons load, number of runs, etc.).
The purpose of the manned simulation was to create a database to develop a digital pilot reaction model. The application of a batch model was necessary in order to generate the large number of computer runs needed to accomplish the project goals. The batch simulation strategy involved three different programs. First, the ‘Arena’ war simulation program was used to model a beyond-visual-range, many-on-many air battle and generate within-visual-range starting conditions. This was a valuable technique that got the study group past the ‘How do we set up realistic WVR combat starting points?’ question. Second, the Air-to-Air System Performance Evaluation Model (AASPEM) was used to model one-versus-one (1 v 1) engagements that were initialized under the Arena-derived starting conditions. Third, the Abductory Induction Mechanism (AIM™) was used to link AASPEM results to Arena as depicted in Fig. 3.
 

Figure 3. Source: Practical Limits of Supermaneuverability and Full Envelope Agility

As you can see by the parsing of function among different models, it wasn’t easy to do complex scenario modeling back in the 80’s-90’s. The primary models had to be linked because neither one could answer the questions ask if used as standalone devices. An evolved MIL-ASSPEM II was part of the USAF’s standard analysis toolkit as late as 2005. It might still be.

The study identified and used probability of kill, probability of survival, and exchange ratio as “the key parameters” using two types of weapons: missiles and guns. For each weapon type they assigned a probability of a kill (Pk) given a ‘hit’. Under a ‘massive-number-of-trials’ modeling effort, they established an average Pk of a (AIM-9L ‘like’) missile of 0.8 for each simulated missile fly-out. The Pk (given a ‘hit’) of the missiles being held constant may have made some of the long-term study quantifiable results more conservative ‘offensively’ and more optimistic ‘defensively’ than optimum, given the lethality enhancements seen with AIM-9 and AIM-120 developments ongoing at the time and later. The advantage of using a constant Missile Pk value is that it prevents missile lethality from dominating the calculations and masking nuances in outcomes due to other variations in the aircraft/missile (as a system) combinations. ‘Pk’ for the gun was more complex, and was based upon a function of the maximum burst length for one firing and the time duration of the gun hits within that burst.

The baseline “good-guys” (Blue aircraft) were assumed to have the ‘agility’ of the X-31, and the baseline “bad-guys” (Red aircraft) represented an “F-18 type aircraft”. Given the study timeframe we can probably assume the “F-18 type” aircraft comparisons were based upon the F-18C/D versions.

The study group ran multiple excursions of the 'sort-of-a-metamodel' they created, exploring the relative impacts of increasing aircraft and weapons capabilities on the outcomes of air combat engagements. A recreation of the contents in the matrix of different test cases explored and as summarized in the study’s Table 8 is shown in Figure 4.

Figure 4. Cases studied in "Practical Limits of Supermaneuverability and Full Envelope Agility"

The engagements were run under set conditions to control the number of variables. The following are the rules of engagement used for 1 v. 1 engagements:

• 120 second duration  

• No kill removals  

• Each aircraft started with same fuel load  

• Each aircraft had 4 missiles and a gun  

• Conditions for gun firing:  

- Minimum range = 500 ft  

- Maximum range = 3500 ft  

- Tracking delay = 0.2 seconds  

- Pipper size = 3.5 MIL (±2°)

All of these criteria were controls based upon expert analysis and historical records except the “No Kill Removals”. The ability to count wins and losses in a test run without ‘kills’ that would remove the killed aircraft from the equation allowed for many more engagements (trials) to add up within each computer simulation run. This approach in modeling was akin to the process of re-spawning adversary aircraft in Red Flag or similar exercises, though with a somewhat different purpose. Today, we would run more trials with actual removals because computer time is cheaper and the runs are faster.

What was learned

Figure 5. The Bottom Line of  Modern WVR Combat

In trying all the various combinations of possible enhancements (and degradations) the authors produced many relevant ‘findings’ associated with each of the design changes and combinations thereof.

1. Aircraft Agility Changes: Blue’s losses were serious, but Red Losses were even worse. Blue losses were seen as high (around 45%) for the baseline case; aircraft agility increased the red losses by 20%, while blue losses increased slightly.  

2. Enhanced Missile Capability: Blue’s losses were still serious, but Red Losses were even more severe. Blue losses were high (around 45%). However, red losses increased drastically to near 70% against the most capable missile option.  

3. Enhanced Avionics: Just improving avionics didn’t help Blue’s effectiveness or survivability. Overall, there was virtually no effect on exchange ratio or losses (which, once again, were around 45%) for the Blue Force.  

4. Combined Short-Range Missile (SRM) and Avionics Enhancements. Blue losses are again high (40-45%). Red losses were slightly lower than that for the same missile using baseline avionics, but still significant approaching 70%.  

5. Aircraft Agility with SRM Enhancements. Losses remained high (up to 52% for blue and up to 66% for red).  

6. Aircraft Agility with Avionics Enhancements. Red losses were again higher than blue losses (20% higher), but both remained high (above 45%).  

7. Combined Enhancements. Again, blue losses were high (48% for the "best" system). Red losses increased to beyond 70%.

The biggest benefit of EFM that could be drawn from the study was that EFM pays off significantly IF the A2A fight STARTS very ‘close in’ under 1 v. 1 situations AND inside the minimum range (Rmin) of the ‘then-era’ of Short Range Missiles with limited OBC (Off-Boresight Capability up to 30°), AND IF no further aircraft enter the combat (remains a 1 vs 1 engagement). Within the study, EFM largely enhanced gun firing opportunities that come well after the initial ‘long-game’ has been played and those outcomes settled. That advantage is now questionable with SRMs that have very high OBS capability. No one has to actually point anywhere near the opponent in WVR combat anymore to be able to take offensive action against that opponent.

And for the readers who just skimmed the WVR engagement outcomes above and didn't see Figure 5, let us now explicitly state that the WVR ‘short game’ IF it comes at all, during the course of this study was determined to be an unsustainable “loser’s game” between comparable opponents. This has now been known for decades, and findings such as these had to have influenced the definition of the F-35’s requirements.

Given that 1) ‘modern’ low observability predates this study significantly-- at least in the U.S.—and 2) low observability makes a foe far more lethal to 4th generation and earlier aircraft as well as more dangerous surface to air systems, it should speak volumes to any reasonable person as to why the design thrust of the F-22 and F-35 (and now others) emphasizes the reduction of susceptibility to being targeted in the first place, while (as in the case of the F-35) also emphasizes the ability to sense, discern, and assist the pilot in dealing with external threats as effectively and efficiently as possible.

We can be certain that the responsible agencies involved conducted manifold similar studies involving the effects and limits of low observability in combination with all other design drivers to produce the latest fighter designs. I can’t imagine what kind of thinking is required by the uninvolved to imagine the professionals make these kinds of analyses and force structure decisions without due diligence.

How many more pilots, planes, and support assets would ‘blue’ forces need to win a war of attrition if only WVR-capable “day fighters” and/or non-‘stealth’ aircraft are involved? This is an important question. After all, simple ‘less capable’ fighters are what all those earnest and/or Faux Reform critics advocate to varying degree when they are insisting the actual experts are doing fighter acquisition “wrong”. Advocates of less capable systems are advocates for a strategy of Wars of Attrition.

The frequency--how often WVR conditions would occur between aircraft (again, they were all non-LO aircraft) -- was to be a subject of the Arena runs of the future. I’ve not found the results of this effort in unclassified sources, but given what we’ve learned from all air combat that has occurred since that time, and experiences in major exercises such as in recent Red Flags, I would suspect WVR encounters, and certainly 'extended turning' fights, will become even more of a rarity.

Given the improved min-range performance of short-range missiles and future non-kinetic weapon solutions on the horizon, extended maneuvering fights might become extinct. At the very least, they could become ‘black-swan’ encounters not worthy of driving aircraft design in the future nearly as much as in the past, that is, at least for the foreseeable future.

How potential enemies see the future is indicated in how hard they work to either follow the US lead in design trends or in attempting to devise ways to mitigate the advantages sought by the U.S. and its allies. “Advantages” such as those that come from the capabilities of the Fifth Generation fighters.

The entirety of EFM-AASPEM work performed during the study was devoted to within-visual-range 1 v. 1 combat. Comparisons were made based on firing opportunities, exchange ratio, and losses. One really needs to read the study to understand the nuances of the findings, but by way of introduction to the findings, let us observe what key conclusions were drawn. [ My comments in brackets]:

• The most significant contribution to operational effectiveness was increased OBC coupled with enhanced avionics (mainly due to helmet mounted displays). Further improvements were possible when Rmin [Minimum Range] was reduced. [Missile Rmins have been getting smaller, and off boresight capabilities have expanded wildly beyond any assumptions in the study since the report was published. The utility of an advanced HMD has been recognized as far back as the earliest F-15 requirements list. It’s good to see technology has finally advanced enough for the concept to have come of age in the F-35.]  

• Missile and avionics enhancements have to be harmonized to fully make use of the improvement potential. It should be noted that missile/avionics OBC enhancements will provide even higher impacts in the many-on-many environment. [And the F-35’s integrated avionics/sensor fusion are now the epitome of this idea made real.] 

• Aircraft agility contributes to a certain extent, although not as significantly as missile/avionics enhancements. To make full use of agility, new aircraft designs might be required concerning aircraft kinematics and aerodynamics. [‘Agility’ as defined by the research pointed to just the kind of design philosophy used for the F-35.]  

• Conventional aircraft performance enhancements do not improve system effectiveness. If envisaged, they would also require new aircraft designs. [Asymptotic limits of maneuverability have been reached. Perhaps it is a plateau for the current technology available, but I would suspect there will have to be a breakthrough no one has yet identified as needing to happen first.]  

• Degraded aircraft performance [Aero efficiency and Thrust to Weight for the most part] can hardly be compensated by enhanced agility. The degradation decreases the conventional turn capability which is a "defensive" potential. A decrease of this potential enables the opponent to generate increased firing opportunities. [In a WVR world fighters will still need to be able to turn and burn. Think of it as the lower limit of maneuverability isn’t going away just because the practical upper limit has been reached.]  

• Degraded aircraft performance might be compensated by suitable missile/avionics enhancements. Although the same degradation concerning "defensive" potential applies, more firing opportunities can be generated earlier. [This is actually not a new thought. If Glenn Bugos’ history of the F-4 is to be believed (and I believe most of it is quite on target), much of the F-4 Phantom design was philosophical: driven by how best to divide the ‘capability’ between the missiles carried and the aircraft carrying missiles and to a lesser extent fleet radar support.]

Some of the last findings in the study report can be said to have become even MORE true since it was written [Brackets still mine]:

During the last 10-12 years, [and now two decades since the study report] there has been significant improvement in missile technology. Next generation missiles [ASRAAM, AIM-9X, etc.] have better seekers and more sophisticated fly-out capabilities to make successful use of better thrust vector control, thereby improving missile agility in the close-in environment as well as endgame performance. [The missile performance realized in today’s generation of missiles exceed that ever envisioned in the study]. In addition, [aircraft] avionics have improved to make use of high OBC. [And of what the study authors would have considered impossibly-high OBC.] These developments [through and past 1995 and that were and are ongoing] make the new generation SRM/avionics attractive; however, the high mutual loss rates [expected to increase further] with all type of enhancements will "stress" the recommendation to urgently improve situational awareness as well as beyond-visual-range effectiveness to avoid WVR/CIC. [And unsurprisingly has been incorporated into the F-35 design.]

“Fighter Aircraft” Design as Always is STILL Driven by Operational Requirements

(Bumped)

Operational requirements have evolved continuously since the first fighters flew. It would be as large a folly to insist that a fleet of 4th generation fighters could meet the needs of current and foreseeable operational requirements as to insist a WWI aircraft could meet the requirements of a WWII operational environment.

Compare what we know now about ‘where’ air-to-air combat is going with the kinds of capabilities built into fighters like the F-35 and F-22, and what potential ‘near-peers’ are trying to build. Given the study findings, 5th generation fighter capabilities, and actual air combat history, WVR combat is now something to be even avoided more; something any A2A combatant would seek to avoid if at all possible and only to be endured if unavoidable.

Defense planning and foresight informed by experience and research, such as that embodied in the study we just reviewed, produces the requirements for future weapon systems that resulted in the F-35. I marvel at how much hybris the uninformed must possess to shamelessly assert alternate realities while second guessing legions of actual subject matter experts who have done the work day-in and day-out for decades to deliver viable solutions to defense requirements, and who have access to the kind of data and history needed to actually carry out such responsibilities.

The future of fighter design and design requirements will change as the operational environment changes. This is why as soon as one ‘generation’ of fighters is being fielded, work begins to define what will be needed in the next generation. Work on what became the F-15 began as soon as the AF got the F-4. The F-22 is descended from the first efforts to define what would be needed after the F-15 as the first F-15s were in development. Yes, we can envision some of these future changes (lasers anyone?) and can imagine how strategists and designers will cope with them. But the entire battlespace will continue to be reshaped beyond any analyst’s imagination and prevent them from peering too far into the future just as it always has been.

NOTE:

Nowhere in this series of posts, or in any other posts the reader will find here, is the assertion made that ‘maneuverability’ (however one defines it) is "unimportant"-- in the past, modern day or immediate future. This must be stated unambiguously up front because I've seen the tiresome broad-brush accusation of same made too often when anyone dares challenge some closely held belief as to maneuverability’s relative importance to fighter design, or dares challenge the vague reasons why many of the uninitiated think “maneuverability” is important.

A Request in Closing: If history repeats itself, when this post is referenced on a ‘board’ or comment thread somewhere, some yahoo is probably going to contest what I have written as “SMSgt Mac is wrong…”. As if their disagreement is with ‘me’-- when they’re really expressing their disagreement with…y’know…the ACTUAL experts I cited. I usually trip over these weak statements. while looking for something else, ages (sometimes years) after the mischaracterization of what I typed is displayed: long after the disinformation damage is done and everyone has since moved on to other topics. Soooo…If one finds this happening somewhere after this post, it would be much appreciated if a reader or two would reply in response that “SMSgt Mac said you would try that B.S. deflection”. Feel free to use the direct quote.



1. Practical Limits of Supermaneuverability and Full Envelope Agility; B.A. Kish, D.R. Mittlestead, G. Wunderlich, J.M. Tokar, T. Hooper, R. Hare, H. Duchatelle, P. Le Blaye; Proceedings from the AIAA Flight Simulation Technologies Conference, San Diego, CA, July 29-31, 1996; PP 177-187; AIAA Paper 96-3493.     

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)

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.

Charter Cable: Media Malpractice

Charter News, 'Isn't'

(Still working on a lengthy 'aircraft/F-35 maneuverability' post, but this HAS to go up tonight.)

Charter Cable is my cable provider. NO complaints about the internet speed or connectivity, not even though I suspect their move to 'all digital' last week wreaked havoc with signals (off and on) as thousands of users finally added even more thousands of cable boxes and cards to the network in just a few days. It now seems to have stabilized, so 'no problem'.

But Charter Cable's 'homepage' has a section with rotating 'news' headline pictures and captions. All too often the caption and photo make it appear that some tragedy has happened in the US or even just the 'Modern' world, and you click on the link talking about a school being bombed with what appears to be a typical American elementary school (they've done school buses too if I recall correctly) and the story is about a school in some war zone in a 'turd world' country. The Chief and I just chalked it up to lazy web content developers and editors.

Today, they went beyond 'lazy' and deep into 'media malpractice' . I got home and booted up the laptop to check the web and this is what greeted me (left headline):



Charter Home Page 9 April 2013 ~1920 Hrs CST

 



WTFO? "Veteran Kills 13"?

I clicked on the link, and this is what popped up:

Charter 'Article' 9 April 2013 ~1920 Hrs CST

Oh. A Serbian 'vet' in Serbia loses it and goes on a rampage. Tragic in it's own right. Why the 'trick' headline?

You would have to be either incompetent or agenda-driven to put this one up.  Either way it doesn't 'inform' but misleads and distorts several issues in one nice swoop.

Besmirching veteran's mental health? Check!

'Tragedy' as background for upcoming 2nd Amendment legislation? Check!

The Chief likes to try and calm me down when some unthinking slug nearly kills us because they're doing something clueless in traffic. She says something like "I'm sure they didn't see us". She forgets what makes me the MOST angry is the fact that they probably were clueless as to what was going on around them. If I assume Charter was just being 'brain dead' in this, it just p*sses me off more. tell me again: What business are they in? Do they have any standards?
 
Either way, Charter's website is Media Malpractice writ large in a Low Information Consumer world.

Are There ANY Adults At Charter Cable?

Air Force Magazine on the Latest From the F-35 Program Vaults: Part 3

Part 3 of what looks like...yep, 3

Part 2 Here

Solomon over at SNAFU! posted a piece centering on an excerpt from an Air Force Magazine article “The F-35’s Race Against Time” (November 2012 issue). I had read it already, and didn’t see anything ‘earth-shattering’ at the time. But with Sol’s posting, it occurred to me that it would probably become more interesting to people the further you got away from those familiar with the current state of aeronautics, and it may draw secondary comments from the anti-JSFers to boot.

 Situational Awareness? You need Data AND Understanding  (Source: www:SLDinfo.com)

Networking & Situational Awareness

As F-35s criss-cross enemy airspace, they also will automatically collect vast amounts of data about the disposition of enemy forces. They will, much like the JSTARS, collect ground moving target imagery and pass the data through electronic links to the entire force. This means the F-35 will be able to silently and stealthily transmit information and instructions to dispersed forces, in the air and on the ground.

I don’t think at this time we can possibly overemphasize how the F-35 systems allow a pilot to gain and exploit superior situational awareness relative to legacy systems nor how much an edge it gives to any F-35 on the network. So I’m going to refer to Barry Watts’ excellent McNair Paper “Clausewitzian Friction and Future War” (Updated PDF version here) for insight on what this means in terms of reducing Clausewitzian Friction for F-35 drivers while increasing the same for their opponents. In the early part of his Chapter 9, Watts leans heavily on R.L. Shaw’s classic "Fighter Combat: Tactics and Maneuvering,"but there is much after it that I’ve read nowhere else.

I’m asking for a slight indulgence here. I’m going to beat a dead horse to again drive home a point the advocates of simple lightweight and ultra-maneuverable fighters NEVER come to grips with: ‘first look’ (almost always) equals ‘first kill’. [To keep clear which quotes are from where, Watts quotes are normal font and the AF magazine quotes are in italics]

What factors have tended to drive engagement outcomes in air-to-air combat? Surprise was linked to general friction in chapter 6. Air combat experience going at least back to World War II suggests that surprise in the form of the unseen attacker has been pivotal in three-quarters or more of the kills. In writing about his experiences flying long-range escort missions over northern Europe with the U.S. Eighth Air Force, P–38 pilot Mark Hubbard stressed that “90 percent of all fighters shot down never saw the guy who hit them.” Hubbard was by no means alone in observing that friction in the form of the unseen attacker from six o’clock played a dominant role in engagement outcomes. The American P–47 pilot Hubert Zemke (17.75 air-to-air kills in World War II) stressed that “few pilots are shot down by enemies they see.” Similarly, the German Me-109 pilot Erich Hartmann, whose 352 kills during World War II made him the top scorer of all time, later stated that he was “sure that 80 percent of kills never knew he was there before he opened fire.”

Subsequent technological developments in the means of air-to-air combat did not change the basic pattern observed by Hubbard, Zemke, and Hartmann during World War II. These developments include the shift to jet fighters for air superiority during the Korean War, the advent of infrared air-to-air missiles by the mid-1950s, and the appearance of radar-guided air-to-air missiles in time for American use in the Vietnam War. The best combat data are from the American involvement in Southeast Asia. From April 1965 to January 1973, American aircrews experienced more than “decisive” air-to-air engagements, meaning encounters in which at least one U.S. or North Vietnamese aircraft was destroyed. These engagements produced some 190 aerial kills of North Vietnamese fighters against 92 American losses. Detailed reconstructions of the 112 decisive engagements from December 18, 1971, to January 12, 1973, revealed that 81 percent of all aircrews downed on both sides either were unaware of the attack, or else did not become aware in time to take effective defensive action. In the jargon of contemporary American aircrews, such failures to be sufficiently cognizant of what is taking place in the combat area around one to avoid being shot by an unseen or unnoticed adversary have come to be described as a breakdown of situation (or situational) awareness. In an air-to-air context, situation awareness (or SA) can be understood as the ability of opposing aircrews to develop and sustain accurate representations of where all the participants in or near the air combat arena are, what they are doing, and where they are likely to be in the immediate future. This understanding of situation awareness is, of course, crucial to appreciating that the driver in 81 percent of the decisive air-to-air engagements in Southeast Asia from December 1971 to January 1973 involved more than just the “element of surprise,” although this was the interpretation at the time. Surprise can certainly affect combatant situation awareness on either side…

… Even without the evidence from subsequent tests like Air Combat Evaluation (ACEVAL) in the late 1970s and the Advanced Medium Range Air-to-Air Missile (AMRAAM) Operational Utility Evaluation (OUE) in the early 1980s , combat data from Europe in World War II and Southeast Asia during 1965–1973 not only confirm the contention in chapter 8 (proposition I) that general friction can dominate combat outcomes, but indirectly quantify what the term “dominate” has meant in historical air-to-air combat. If some 80 percent of the losses have resulted from aircrews being unaware that they were under attack until they either were hit or did not have time to react effectively, then a relative deficit of situation awareness has been the root cause of the majority of losses in actual air-to-air combat. A deficit in situation awareness accounts for four out of five losses. While this statistic may not measure frictional imbalances directly, it does reflect the influence friction has had on outcomes over the course of large numbers of air-to-air engagements.

“You’re only about one-third as efficient as you think you are [at sorting in complex engagements], which is why you go out with a sexy missile and lose your ass anyway.”

Watts goes on to iterate the ‘surprising’ (to some) AIMVAL/ACEVAL and the AMRAAM OUE results, then follows up with a discussion that hints as to what the F-35’s SA advantage brings to the mix (Boldface mine):

By 1984, Billy R. Sparks, a former F–105 “Wild Weasel” pilot with combat experience over North Vietnam, had been involved in analyzing or running three major humans-in-the-loop tests: AIMVAL/ACEVAL, the AMRAAM OUE, and the Multi-Source Integration test (also conducted in simulators). Yet, in reflecting on all that experience, Sparks felt that he had not once witnessed perfect sorting in 4-v-4 and more complex engagements. “You’re only about one-third as efficient as you think you are [at sorting in complex engagements], which is why you go out with a sexy missile and lose your ass anyway.” As Clausewitz wrote, in war “the simplest thing is difficult,” and it is hard for normal efforts to achieve even moderate results. Such observations go far to explain why even small SA deficits relative to the opposition have been statistically more dominant in engagement outcomes than differences in aircraft, weapons, force ratios, or other conditions such as having help from GCI. It also strongly suggests that friction’s influence on outcomes in air combat during World War II was not noticeably different in Korea’s “MiG Alley,” the Vietnam War, the Middle East in 1967, 1973, and 1982, or even in Desert Storm. In this sense, general friction’s “magnitude” does not appear to have diminished noticeably over the course of all the technological advances separating the P–51 from the F–15.

Could information technology be used to mitigate this longstanding pattern of very low sorting efficiencies in complex engagements arising from seemingly small lapses in situation awareness? Early experience in 4-v-4 and more complex engagements with the recently fielded Joint Tactical Information Distribution System (JTIDS) indicates that the answer is “yes.” JTIDS not only provides integrated, all-aspect identification of friendlies and hostiles based on available information, but even displays targeting decisions by others in one’s flight. The aggregate gains in air-to-air effectiveness resulting from these improvements in situation awareness and sorting have been nothing less than spectacular. During Desert Storm, F–15Cs, aided in most cases by E–3A Airborne Warning and Control Systems (AWACS) aircraft, downed 28 Iraqi fighters without a single loss, including 15 kills from engagements that began with BVR shots. When JTIDS–equipped F–15s flew against basically the same fighter/AWACS combination that had done so well in the Gulf War, the JTIDS “information advantage” enabled them to dominate their opponents by exchange ratios of four-to-one or better. Hence technology, properly applied, can certainly manipulate the differential in friction between opposing sides to one’s advantage at the tactical level.

The F-35 MADL capability adds another dimension beyond the JTIDS/LINK16 capability: More information and more kinds of information integrated and synthesized for easy (i.e. transparent) operator consumption and shared over a more secure link for use while skulking about in ‘Indian Country’. The system ‘sorts’ for the pilot. (Now you know why Northrop Grumman bothered with highlighting this capability in producing this video.)

Hey, Here’s That ‘Maneuverability’ Thing Again!

Because it was designed to maneuver to the edge of its envelope with a full internal combat load, the F-35 will be able to run rings around most other fighters, but it probably won’t have to—and probably shouldn’t.

"If you value a loss/exchange ratio of better than one-to-one, you need to stay away from each other," said O’Bryan, meaning that the fighter pilot who hopes to survive needs to keep his distance from the enemy.

He noted that, in a close-turning dogfight with modern missiles, even a 1960s-era fighter such as the F-4 can get into a "mutual kill scenario" at close range with a fourth generation fighter. That’s why the F-35 was provided with the ability to fuse sensor information from many sources, triangulating with other F-35s to locate, identify, and fire on enemy aircraft before they are able to shoot back.

The F-35’s systems will even allow it to shoot at a target "almost when that airplane is behind you," thanks to its 360-degree sensors.

According to O’Bryan, the F-35 also can interrogate a target to its rear, an ability possessed by no other fighter.

If you survive a modern dogfight, O’Bryan claimed, "it’s based on the countermeasures you have, not on your ability to turn."

I think that last comment is a slight overstatement. You want to be able to get out of a jam if you get your self into one. The fact that the F-35 probably won't lead you into a bad spot, doesn't mean it won't keep a really determined pilot from getting into one on his own.

Options… Options…

If the situation demands a turning dogfight, however, the F-35 evidently will be able to hold its own with any fighter. That is a reflection on the fighter’s agility. What’s more, a potential future upgrade foresees the F-35 increasing its air-to-air missile loadout from its current four AIM-120 AMRAAMs to six of those weapons.

Since the F-35’s biggest advantages (that are talked about publically anyway) in going up against large numbers of adversaries are its Stealth and its situational awareness provided by on-board/off-board systems, I’d say even the 4 AMRAAM loadout should be seen as ‘sufficient’ for otherwise pretty scary “bad guy/good guy” ratios of 3-4 to one. A 6 AMRAAM (or follow-on missile in perhaps greater numbers) loadout? Even better.

The F-35, while not technically a "supercruising" aircraft, can maintain Mach 1.2 for a dash of 150 miles without using fuel-gulping afterburners.

That works out to about 12 ½ minutes of ‘dash’ at 30K feet. The fact there is a time limit indicates that supersonic drag is slowly pulling the plane down to subsonic at Mil Power. The fact that it would take about 12 and a half minutes at 30K feet is indicative the plane is pretty slick aerodynamically without external stores. Even if the reason has to do with having no external stores and nothing else, that makes the F-35 far superior to any alternative that would be dragging around external stores.

"Mach 1.2 is a good speed for you, according to the pilots," O’Bryan said.

This is a mildly interesting data point, as M1.2 is commonly understood as the point where the definition of “transonic” ends and true “supersonic” begins (see chart below).

At Mach 1.2, you are usually still high on the supersonic drag rise. Source: DESIGN FOR AIR COMBAT,, Pg 46,  Ray Whitford   Update: Graphic now showing drag rise for swept wing configuration vs. straight wing.

 If Mach 1.2 is a ‘good speed’, then I would deduce that probably means that the F-35 supersonic aerodynamic drag, the F-35 installed thrust, or simply the F-35 thrust/drag ratio is among the best possible for a fighter operating within the laws of physics and given current propulsion/airframe technologies.Though may not be a ‘worldbeater’, it will hold its own aerodynamically, and it definitely means the F-35 is nowhere near a ‘dog’ as some might fear (or hope).

A Questionable Advantage (AKA “4th Gen Fighter Think in a 5th Gen World”)

The high speed also allows the F-35 to impart more energy to a weapon such as a bomb or missile, meaning the aircraft will be able to "throw" such munitions farther than they could go on their own energy alone. 

As I noted in the comments at Sol’s SNAFU! site, I really don’t see a very large benefit here. I do see an artifact of the ‘speed is life’ religion.

'Fairly Easily'?

There is a major extension of the fighter’s range if speed is kept around Mach .9, O’Bryan went on, but he asserted that F-35 transonic performance is exceptional and goes "through the [Mach 1] number fairly easily." The transonic area is "where you really operate."

Agreed.
But I wonder about the earlier ‘warning signs’ that the transonic acceleration time KPPs were unlikely to be met? Perhaps this hints at changes to the KPP? If so, I believe it would be completely justified: The spec was originally written to surpass or equal those of legacy systems, but as far as I can determine, all legacy aircraft performance was verified/validated using a clean, unarmed configuration.
Since there is no aerodynamic difference between the F-35 in its primary unarmed or armed configuration (internal stores only), the KPP should have been written to be one that was based upon legacy platforms combat capabilities with loadouts comparable to the F-35’s internal load. This would have kept the relative measure comparison an ‘apples to apples’ exercise. A potential side-benefit of changing the KPP might be the entertainment value from inducing know-nothings to whine about the F-35 ‘cheating’ on KPPs…again.

More Range? Mo Bettah!

In combat configuration, the F-35’s range exceeds that of fourth generation fighters by 25 percent. These are Air Force figures, O’Bryan noted. "We’re comparing [the F-35] to [the] ‘best of’ fourth gen" fighters. The F-35 "compares favorably in any area of the envelope," he asserted.

Conclusion:

The F-35 is an all aspect low observables, net-centric systems, long-range, yankin’, bankin’, killin’ machine.

Works for me.

An Airpower History Lesson in 3 Parts

Updated: F-108 Mission (Below Original Post)

---------------------------

B-52 vs. Flying Wing?... B-70 Canceled: Why?... What exactly WAS the F-108 'Mission'?

In a recent comment thread, three questions were raised as to the facts surrounding 50s-60s aircraft program histories. Normally I would blow off trying to address such diverse issues even those as narrowly defined, in one post. But it just so happens all involve information I already know via sources I’ve already acquired for other purposes.

Last of the '49's: YRB-49A in flight

In this post I intend more to let the sources tell the facts vs. my making observations on the facts: ie, this post will be heavy on the quotes, light on the sidebars. It will also ensure I don’t spend a lot of time that I can better spend elsewhere.

Flying Wing Was an option to B-52 Development

As I showed in an earlier post, the B-52 for a while faced extinction until a program cancellation decision was fortunately reversed. One of the B-52’s competing concepts, contrary to what you may have been told, was the Northrop B-49 flying wing, a jet variant of the earlier propeller-driven theme. Fielding the ‘flying wing’ would have been the fruition of Jack Northop’s lifelong dream, but alas it was not to become true until after he passed away. He did die knowing the wing WOULD fly in the form of the B-2 Bomber. I could detail ‘why’ the flying wing was B-52 competitor but that is beyond the scope of this post. To the sources we go!

The year 1948 began under a dark cloud for AMC’s B-52 program managers. Air Staff officers succeeded in canceling, not simply Boeing Model 464-29, but the entire Boeing heavy bomber program due to doubts about the B-52’s ability to achieve the required range and speed. Some Air Staff officers preferred the Northrop YB-49 turbojet powered all-wing aircraft over Boeing’s conventional B-52 design: others favored opening a new competition for a heavy bomber. (Mandeles, pg 49)

Craigie added that AMC analyses of other studies of optimum airplane performance relied on extrapolations from past performance. However, these extrapolations were unreliable because aeronautic and aerodynamic knowledge was growing so quickly. Therefore, it was necessary to use the most current data and knowledge, which did not necessarily involve only extrapolations of past performance. For instance, he noted, that in 1941 Douglas Aircraft Company analyzed the predicted performance of the B-36, and concluded that the requirement of a 10,000-mile range with a 10,000-pound payload was unlikely to be achieved. The Air Force and Convair, however, used improved weight control and planning, and proved the study wrong. Despite increases in armament, radar, equipment, and the difficulty of development under wartime conditions, Convair and the Air Force produced an airplane which could meet the Air Force’s objectives. Craigie also urged discarding the alternatives to the B-52-the XB-35 and YB-49 Flying Wing and delta-wing designs. By May 1947 the delta wing did not have any marked superiority over a conventional airplane for long-range, high -speed operation. Craigie wrote that a reevaluation of these designs should be made only when “jet engine specific fuel consumption is reduced to a point to permit their [sic] use” in a bomber. (Mandeles, pgs 75-76)

At AMC, senior officers attempted to save the B-52. Maj Gen Franklin O. Carroll, AMC’s director of R&D, analyzed Northrop’s claims of superiority for the Flying Wing, and found them wanting. The basic premise for proponents of the all-wing aircraft was that the space requirements for military stores matched the space available in the optimum wing. Under this assumption, the all-wing aircraft would be more efficient than the conventional airplane. Carroll, however, argued that Northrop seriously underestimated the space needed for military stores. More space would be needed in the aircraft, and adding a body or nacelle to contain the extra military stores would vitiate the theoretical advantages of the all-wing design. The YB-49 Flying Wing also demonstrated longitudinal instability at high speed. Little was known about this instability and it could present severe engineering difficulties. The flying wing would not be versatile in a tactical setting and would be overly sensitive to changes of center of gravity caused by the position or absence of cargo. Such problems seemed not to justify reliance on the all-wing design. Carroll concluded by recommending the conventional Boeing design and that the B-52 be accorded the highest support from Air Staff. (Mandeles, pg 83)

Several days after the Symington-Allen meeting, Craig, Frederic Smith, and Craigie decided that “if the B-52 meets the requirements of the contract under which it is being bought, it will satisfy strategic requirements.” These requirements included unrefueled range of approximately 8,000 miles and a cruising speed of 500 MPH over 4,000 miles of enemy territory. 103 Boeing Model 464-35 (fig. 4) matched these strategic requirements, and Air Force Undersecretary Barrows confirmed the decision to retain Boeing as prime contractor of the heavy bomber rather than adopt the Flying Wing in early March. (Mandeles, pg 83)

Partridge and Craig urged the staff to stand firm, noting support from RAND and the National Advisory Committee for Aeronautics for the Flying Wing design. At Symington’s urging, Allen agreed to give the Flying Wing due consideration. After further discussion, key members of the Air Staff met on February 14, 1948, and decided to keep the Boeing contract and issue a change order. Undersecretary Barrows concurred in the action. Despite the painful experience, the B-52 program had been radically redirected and was now aimed at fulfilling a new concept of strategic air operations. Thus even before the Aircraft and Weapons Board met in January, two of the major proposals up for consideration had already been approved. Both the B-36 and the B-52 had received a new lease on life, as had, incidentally, the Northrop YB-49 Flying Wing. (Moody, Pgs 182-183) Note: 'Moody' is a huge PDF file.

Read the complete sources for more information illustrating the point that the flying wing, specifically the YB-49 version was ‘competition’ for the B-52, and the whys and hows the B-52 came out on top.

Why was the B-70 Not Pursued?

North American XB-70 'Valkerie'

That the B-70 was cancelled because of ICBMs and the existing capabilities of the B-52 being sufficient is easily shown, but I’m not going to type the proof out, just show it in situ:

Source (can't find my copy dangit!):
"Politics and Force Levels: Politics and Defense Inside the Kennedy Administration", Pg 216

(The footnote #10 referenced is “President Kennedy, Special Message, Pg 11)

The F-108 Rapier Mission? Long Range Interceptor

If one believes in infallible ‘fact sheets’ the F-108 according to one 'fact sheet', was to have two missions: Long Range Interceptor and Escort Fighter for the B-70. Evidence supporting the escort mission assertion is so thin, it is ’invisible’, while evidence supporting the Interceptor role is bountiful.

XF-108 Rapier: Never Reached Beyond Mock-up Stage

As I've noted to a commenter, I did not say or imply it (F-108) couldn’t or wouldn’t be an escort fighter if the need arose. I would assume it would do any ‘fighter’ mission it was assigned to varying degrees of success. I also asserted: There can be little doubt that there was someone, somewhere in the entire AF command structure who thought it would be a good ancillary/alternate mission for the F-108, but it was not part of the F-108 design requirements NOR was it part of F-108’s operational concept. I will say now that I would consider the ‘factsheet’ to be wrong in asserting an escort role (beyond possible for any fighter as a generic capability).

Most critically, given the nature of the operational concept envisioned for the F-108 and planned end strength, the use of the F-108 as an ‘escort fighter’ would probably be less likely than the F-106 it was designed to replace. This too is easily shown. And now it will be shown, thanks to my  serendipitous and very slight connection to the author of the following in his 1988 ACSC paper titled: “The Search for an Advanced Fighter: a History From the XF-108 to the Advanced Tactical Fighter”.

Then Major (later Colonel) Robert Lyons wrote (beginning on Page 4):

The MX1554 "Ultimate Interceptor, 1954" produced the Convair F-102 that fell far short of the planned speed, altitude, and range performance (95:159-165). It could only fly at 677 Knots at 35,000 feet, with a maximum ceiling of 51,800 feet and 566 nautical mile combat radius (95:173). While the F-102 and its follow-on F-106 served as "interim interceptors," the Air Force developed requirements for a long range interceptor. These long range interceptor requirements, first developed in April 1953, were rewritten in July 1955 and November 1956, after several attempts failed to get an acceptable proposal from competing airframe contractors (114:Ch 2). The Air Force sought an interceptor to counter the perceived 1960 bomber threats of Mach 2.0 speed at 61,000 feet, and the revised 1963 bomber threats of Mach 2.2 to 2.7 speed at 65,000 feet (118:7,32; 114:Ch 2). Design studies to satisfy these requirements began in 1953 at Air Research and Development Command and in industry with the MX1554 designed to achieve a Mach 4.5, 150,000 pound Gross takeoff weight aircraft, but the aircraft appeared to lie beyond the state of the art (118:7,Fig 24). So another round of design studios attempted to meet the 1955 LRI (long range interceptor) requirements. These studies called for an aircraft with a cruise speed of Mach 1.7 at 60,000 feet and combat speed of Mach 2.5 at 63,000 feet, with a gross takeoff weight of 98,500 pound, But this aircraft would have had only marginal capability against the postulated 1963 bomber threat (118:7,Fig 24). 

A subsequent design competition in 1955 between Lockheed, Northrop, and North American was little better than previous ones, but North American came closest to meeting the goals, (114:23).

North American Aviation's letter contract of 6 June 1956 called for a long range interceptor that could operate at 70,000 feet with a combat speed of at least Mach 3. The all-weather interceptor aircraft was to have two engines, two crewmen, and at least two internally carried nuclear or conventional air-to-air missiles (95:330-331). Their Weapon System 202 configuration sported a single vertical tail and large delta wing, and was adopted in 1958 after considering iterations with as many as three vertical tails and a large canard (118:7, Fig 24; 95:331).

In 1960, toward the end of the heyday of the "Century Series" fighter aircraft, Weapon System 202, renamed the XF-108 Rapier interceptor, promised to serve the Air Force with a Mach 3 cruise speed and 1,000 nautical mile range as a companion to the proposed B-70 supersonic bomber (106:44). [SMSgt Mac Note: I believe the fact that the Rapier was based on common design concepts with the B-70, coming out of the same design stable and discussions concerning the parallels in performance parameters may be as much of a source of ‘escort’ fighter role stories for the F-108 as any other. ]  The XF-108 design evolved to meet all of the expected Soviet bomber threats of the early 1960s. It was to have been fabricated from stainless steel sheet, a welded sandwich and honeycomb, rather than aluminum to withstand the high temperatures and stresses of sustained supersonic flight. Its two General Electric J93-5 turbojet engines were to have used a special high energy synthetic fuel (ethyl borane) (7:14). It would also use the ASG-18 Fire control system, and the GAR-9 missile. All these were under development simultaneously with the basic airframe. This combination of features allowed a totally new concept of long range interception of the supersonic bombers believed to be under development by the Soviet Union. The F-108, with its superior radar and high speed missile, was to patrol the DEW (Distant Early Warning) Line and make SAGE (Strategic Air Ground Environment) directed, semi-autonomous interceptions well before incoming bombers could launch their weapons against the major cities of Canada or the United States (118:7-8,Fig 25-26,Fig28-30). 

But intelligence sources eventually proved a serious Soviet bomber threat did not exist. That news reinforced growing concerns in the Department of Defense (DoD) over the cost and viability of manned aircraft. Offensive and defensive missiles now seemed to be the logical technological choice for the 1960s (7:14; 8:7). In August 1959 the Air Force canceled the chemical fuel development program (7:14), and on 23 September canceled F-108 development (94:402; 8:7). The Air Force announced that the program had no technical difficulties and had met all goals it the time of cancellation, but that there was a shortage of funds and programming priorities had changed (57:63). Both the fire control system and the missile developments continued at a lower level of Funding. The cost estimate of five to eight billion dollars for a few squadrons of F-108s was more than could be accepted to replace the F-106, given the doubtful nature of the threat (7:14) and the unresolved fate of future manned aircraft.

With the cancellation of the F-108, there appeared temporarily to be a hiatus in supersonic interceptor work in the United States. Indeed, although the Air Force continued trying to gain support for new interceptors in general and the F-108 in particular, the DoD continued to oppose the requirement pending verification of a threat (9:3).

7. Air Force Times. 15 August 1959, p. 14.

8. Air Force Times. 3 October 1959, p. 7.

9. Air Force Times. 11 March 1964, p. 3. 57. "F-108 Cancelled." Canadian Avionics (November 1959), p.63.

94. Kennedy, William V. "Future of the Fighter." Ordnance (January-February 1970), pp. 402-406.

95. Knack, Marcelle Size. Encyclopedia of US Air Force Aircoraft and Missile Systems Volume1. Washington, D.C.: Office of Air Force History, 1978.

106. McCormacK, James, Jr., Maj Gen, USAF (Ret). "How the Air Force Is Buying Its Newest Manned Weapons." .Skyline (Fall 1958), pp. 44-47.

114. "NORAD's Quest for NIKE Zeus and a Long-Range Interceptor."(U). Ent AFB, CO: HQ NORAD/HO, 1962. SECRET-Declassified 31 December 1962. "Unclassified information only used from this source."

115. Neufeld, Jacob. "The F-15 Eagle: Origins and Development 1964-1972." (U). Pentagon, Washington, D.C.: HO USAF/HQ November 1974. SECRET "Unclassified information only used from this source." 

118. Parsons, T. R. "B-70 and F-108 Perspectives on Supersonic Cruise." .Proceedings of the Conference Ob the Operational Utility of Supersonic Cruise (U).Wright-Patterson AFB, OH: ASD/XR, May 1977. SECRET.-Declassified "Unclassified information only used from this source."

From the combination of the limited number of F-108 platforms, the operational concept of roving long-endurance patrols conducted at the farthest distances from home with limited and possibly nuclear payloads, as well as the intended purpose of replacing ‘interim’ interceptors, it is doubtful the F-108 would have had time for anything other than its interceptor role. If the Rapiers were to be ‘escort’ fighters at all, it would be in accompanying aircraft returning post-nuclear strike that might wander/enter their patrol areas, in a manner of what ANY fighter or other aircraft would do.

Updated 26 April 2012:

The  "Standard Aircraft Capabilities" of the F-108

Commenter BB1984 below reminded me of another public resource we can draw on in evaluating the accuracy of the Air Force’s F-108 ‘fact sheet’. Based upon review of the F-108’s Standard Aircraft Capability (SAC) sheets, from the earliest available at the resource (2 May 1958) to the last one available, 12 June 1959 (which was less than 6 months before the program was cancelled) we find two key points:

1. The F-108A mission was pure "long-range ‘interceptor". Anything else it could do would fall under ‘miscellaneous’ capabilities to be employed the same as for any GI’s job description: ‘other duties as required’.

From the 12 June 1959 F-108A SAC:

The primary mission of the F-108 weapon system is to deter armed attack against the U.S. and its area of defense responsibility by providing maximum defense potential against all airborne threats in the post-1962 time period. This defense function is implemented by the F-108’s potential to search out, evaluate, and destroy these hostiles at ranges beyond the capabilities of other defense systems. The F-108 is designed to operate not only in conjunction with SAGE and in cooperation with other weapons in the defense inventory, but to be equally effective well beyond the bounds of ground environment surveillance and under minimum operational control, relying on its self-contained high performance search, navigation, and communications equipment.

In time of war, F-108 operations can include directed intercepts and organized search missions resulting in repeated attacks with up to three kills by each interceptor. Operating beyond SAGE, the F-108 can make positive identification of DEW line violations, attack and trail hostile raids through remote areas, and report directly via long-range radio. Operating within the ZI, the F-108A performance features of all-weather capability, long range at Mach 3, and 15-minute turn-around, permit flexible commitment of forces to achieve the precise concentration of power required at any battle area with maximum retention of reserves.

The F-108A carries two crewmen and internally stowed missile armament. This high performance air vehicle cruises and combats at mach 3 with a 1000-nautical mile radius on internal fuel. It has a 1.2g maneuver ceiling in excess of 77,000 feet and a zoom-climb ceiling of 100,000 feet. Under normal loading and weather, the air vehicle requires runway lengths of only 3200 feet for take-of and landing. It can be operated from 6000-foot runways in all conditions of weather.  From a nominal 70,000 foot combat altitude , missile launch can be accomplished against any air-breathing target flying at altitudes from sea-level to 100,000 feet. The pulsed-doppler radar, with 40-inch antenna, provides target detection in excess of 100 nautical miles at all altitudes and is backed up by infrared search and track devices.

F-108A = Long Range Interceptor. First, Second, Last.

2. The weapons capability from beginning to end consisted of a payload of 3 GAR-9 missiles.  No Guns, No Bombs.No Rockets**

12 Jun 59 Standards Aircraft Capabilities Sheet, Weapons Sections

AF Museum and History Program's 'Factsheets': Swing and Miss

Unless someone threw ‘bombs’ on the F-108 in the last couple of months of the program trying to save it from the axe, The AF Museum and History Program has some ‘splainin’ to do. But even if it was an idea thrown out there in the death throes, if it didn’t get buy-in from the users, it didn’t count, in which case they still have some ‘splainin’ to do.

 **Definition of the term "rocket" in this timeframe was transititory. The GAR-9 indicated above stood for 'Guided Air Rocket'. The weapon would soon be renamed 'AIM-47' for 'Air Intercept Missile'-47. For real confusion look up the GAR-1 and it's short distinction as the 'F-98' before becoming the AIM-4. (the BOMARC was also known as the F-99 at the same time).

Debunking The Close Air Support Myths: Part 6

CAS, the Air Force, and the A-10
Part 6: A-10s 'Forever' ?
(scroll down for links to Parts 1-5 and 'Sidebars)

As noted previously, the A-10 design was from the very start designed to be operated in a ‘permissive environment’. This limitation had been a concern of AF planners since the A-10’s inception, and its vulnerability to weapons larger than those it was designed to encounter became more of a concern with the advent and proliferation of Man-Portable Air Defense Systems (MANPADs) such as the SA-7 (and successors) as well as increases in numbers and types of larger mobile systems that filled the gap between short range low-altitude MANPADs and longer-range high-altitude fixed site systems (SA-2/3s and successors). Before the A-10 was even out of flight test, evidence that the battlefield was getting a lot nastier was seen in the 1973 Arab-Israeli ‘October War’:

Egyptian SAMs (SA-2s, SA-3s, and SA-6s) along with 23-mm ZSU23-4 antiaircraft cannons destroyed some 40 Israeli aircraft in the first 48 hours of the war, or 14 percent of the frontline strength of the IAF.3 In contrast, only five Israeli aircraft were destroyed in air-to-air combat during the entire conflict. Coupled with the high number of aircraft lost to ground-based air defenses in Vietnam, the results of the October War prompted some analysts to ask whether tactical aircraft had outlived their usefulness on the modern battlefield.(link)

Air planners saw the world’s Integrated Air Defense Systems (IADs) evolving at an alarming rate and anticipated that flying low-and-slow would soon be a poor survival strategy. 
Other developments were also occurring that would influence AF attitudes and decisions concerning future CAS capabilities:

1. Israeli successes with the F-16 in the Osirak Reactor Strike (air-to-ground) and the Bekaa Valley (air-to-air) “reenergized proponents of fast multi-role fighters”.

2. The emergence of the Army’s Air-Land Battle doctrine which “envisioned a faster and freer-flowing battlespace without a traditional battle line”. This was a doctrine that clearly favored use of a faster aircraft and operations that were less reliant on air-ground coordination.

3. The discovery that the A-10’s structural design life was significantly less-than-specified, and that would require remedy either via an extensive and expensive modification program and/or replacement of much of the A-10’s structure or the development of a replacement aircraft far earlier than anticipated.

All these factors contributed to the Air Force considering an A-10 replacement that was a ‘fast mover’ and viewing an F-16 variant as a good candidate for that replacement. Making aspersions that the Air Force ‘doesn’t want to do Close Air Support’ because it has sought (and seeks) to perform the mission using resources more survivable than a relatively ‘low and slow’ platform such as the A-10 says more about the ignorance of what is necessary in performing the CAS mission by those making such accusations than anything else. 
If one were to make a list of all the things that the A-10 brings to the battlefield that make it a good CAS platform, none of them are directly dependent upon the ability to fly ‘low and slow’ : its ability to fly low and slow enables it to provide timely and effective CAS in  many cases...in a highly permissive environment, but timely and effective CAS can be provided in any number of different combinations of weapon systems and tactics See here and here for examples. 

General Chuck Horner, the 'Air Boss' in Desert Storm, gets to have the last word on whether the A-10 or an A-10 'like' platform qualifies as the 'best' CAS tool in the future (LINK):

Q: Did the war have any effect on the Air Force's view of the A-10?
A: No. People misread that. People were saying that airplanes are too sophisticated and that they wouldn't work in the desert, that you didn't need all this high technology, that simple and reliable was better, and all that.
Well, first of all, complex does not mean unreliable. We're finding that out. For example, you have a watch that uses transistors rather than a spring. It's infinitely more reliable than the windup watch that you had years ago. That's what we're finding in the airplanes.
Those people . . . were always championing the A-10. As the A-10 reaches the end of its life cycle-- and it's approaching that now--it's time to replace it, just like we replace every airplane, including, right now, some early versions of the F-16.
Since the line was discontinued, [the A-10's champions] want to build another A-10 of some kind. The point we were making was that we have F-16s that do the same job.
Then you come to people who have their own reasons-good reasons to them, but they don't necessarily compute to me-who want to hang onto the A-10 because of the gun. Well, the gun's an excellent weapon, but you'll find that most of the tank kills by the A-10 were done with Mavericks and bombs. So the idea that the gun is the absolute wonder of the world is not true.

Q: This conflict has shown that?
A: It shows that the gun has a lot of utility, which we always knew, but it isn't the principal tank-killer on the A-10. The [Imaging Infrared] Maverick is the big hero there. That was used by the A-10s and the F-16s very, very effectively in places like Khafji.
The other problem is that the A-10 is vulnerable to hits because its speed is limited. It's a function of thrust, it's not a function of anything else. We had a lot of A-10s take a lot of ground fire hits. Quite frankly, we pulled the A-10s back from going up around the Republican Guard and kept them on Iraq's [less formidable] front-line units. That's line [sic] if you have a force that allows you to do that. In this case, we had F-16s to go after the Republican Guard.

Q: At what point did you do that?

A: I think I had fourteen airplanes sitting on the ramp having battle damage repaired, and I lost two A- 10s in one day [February 15], and I said, "I've had enough of this." ....

The Air Force Tried to Give the A-10 to the Army?
One of the most recent episodes fueling the “Air Force Doesn’t like CAS” myth often pops up in real and virtual discussions on the subject as a form of 'proof' or evidence is the simplistic claim that “the AF tried to give the A-10 to the Army”. This argument has its roots in a singular event after Desert Storm, when General Merrill McPeak, shortly before his retirement as Air Force Chief of Staff, proposed a radical change in DoD and Service responsibilities based upon his particular view of “roles and missions”. The A-10 ramifications were collateral damage in the scheme of things. It was McPeak's view that such a restructuring would reduce redundancy and exploit each Service’s strengths to the most effective level.

Per 'Learning Large Lessons' (p.197), McPeak asserted:

In my view, modern land warfare can be seen as containing four “battles”—the rear battle, which includes all the base and supporting elements; the close battle, in which the main opposing ground forces engage one another; the deep battle, which includes hostile territory well beyond the line of contact; and the high battle, the arena of air and space combat. . . . The rear and close battles should be the responsibility of a ground forces commander, an Army or a Marine Corps officer. His forces should be capable of relatively autonomous operations—they should be capable of engaging the enemy in the friendly rear and immediately in front of them, without a lot of outside help. True, the ground commander has a deep and abiding interest in what goes on overhead in the high battle or over the horizon in the deep battle and he may even have some capability to get into these fights. But, his forces are not the most effective for the high or deep battle. Air assets provide the best, most often the only capability to operate in these parts of the battlefield. . . . [T]his approach to dividing battle space provides a logical starting point for identifying unnecessary overlap and duplication. If you accept the scheme I just laid out, it follows that the commander with responsibility for the close battle does not require systems or capabilities that reach across the boundaries into the deep and high battles. If there are such systems in the field or on the drawing board, they might be good candidates for retirement or transfer to another service. Alternatively, the commander with responsibility for the deep battle does not need forces that are configured for direct support of close combat operations. If there are any, they too could be transferred out. 

McPeak called for the Army to give up the ‘deep battle’, the Air Force to give up ‘close battle’, and called for, among other things, the other services to get out of ‘space’ operations. His proposal (thankfully) went nowhere with the other services nor anyone else in the Air Force. Thus, the ‘give CAS to the Army’ was the idea of one man – now long gone and most definitely ‘not missed’, as part of a complete realignment of service roles and missions, essentially dictated by geography of the battlespace.

There were very large problems with inter-service cooperation and conflict that McPeak saw and was trying to solve. The challenge was real, but his solution would have created as many problems as it would have solved, even without entrenched interests subverting such an effort (and there would be). Desert Storm experience, if it did nothing else, clearly exposed the Army’s parochial and incorrect view that Airpower is nothing more than a support element. When in reality it should be viewed as a maneuver element.
Updated and expanded references 7/28: Some excellent papers on differing Airpower-as-manever-or-support views (large .pdf files at links):

Thunder and Lightning: Desert Storm and the Airpower Debates (1995)
Airpower and Maneuver Warfare (1994)
Integrating Joint Operations Beyond the FSCL (1997) (Army POV with AF POV Intro)
Unity of Effort: Crisis Beyond the FSCL (1999) (Army POV on resolving ambiguities in Joint Doctrine)

Conclusions

Thus we have found:
 
1. The Air Force supports the CAS mission better now than when it was part of the Army.

2. The Army was the primary antagonist in creating inter-service friction over CAS post-WWII and in it's Army-Centric way of war it continues to generate friction to this day.

3. CAS is a mission NOT a platform.

Post Script: 
There were a lot of sub-topics we could have pursued and I was/am tempted to further explore the effects of organizational culture and tendencies of the services on the CAS debate, but I fear that will drive the discussion down a ‘rabbit hole’ from which there may be no return. There are also some interesting dynamics now changing the Army’s way of fighting that could lessen the perceived friction between the services, but I am content to simply monitor them for the present time. I could have also expanded greatly on what makes up 'Effectiveness' for a CAS mission. Finally, the Marines insistence on being the primary provider of CAS as an organic USMC function is another topic for another time.

Update 7/27/11@~19:45hrs: Added part of a response that Gen Horner made in the Q&A above that had been dropped in copying the file from a word document to Blogger.(Now the answer makes sense.)

Part 1: The “Big Two” Close Air Support (CAS) Myths
Part 2: Those "not so good old days”
Part 3: Vietnam and the Rise of the “No-CAS Air Force” Myth
Part 4: Origins of the A-X Program
Part 5: Defining a New CAS Platform: the Evolution of the A-10
CAS Myths Sidebar: The A-10 and the 'Cult of the Gun'
CAS Myths Sidebar: Army-Air Force Views on CAS and Airpower
Second Edition: 
Part 7: Sourcing AF Hates A-10 Nonsense
Part 8: The AF 'Had To" Buy a CAS Plane?