Saturday, August 10, 2013


The Navy’s Unmanned Carrier Launched Surveillance and Strike (UCLASS) aircraft development program has issued an initial RFP for continued prototype work to four companies.  Unfortunately, actual specifications have been hard to come by.  The United States Naval Institute (USNI News) has released a few details (1).

Persistence/Range – UCLASS should be able to perform two orbits around its launch point at a range of 600 nm or one orbit at a range of 1200 nm.  It should be able to conduct a strike mission at 2000 nm.  A quick calculation shows that to be a total range of 8,000 nm or so - awfully impressive (skeptically so?) for a craft that size.  I'm not sure I believe that's possible.

Carrier Compatibility – UCLASS should be able to take off and land in Sea States up to 7 (29 ft waves).

Weapons/Payload – Payload is 3000 lbs and should include EO/IR capability.  A third (1000 lbs) of the payload must be existing carrier weapons.  A self defense payload is required although the details were not specified.

Communications – UCLASS should be compatible with existing communications systems including beyond line of sight and should be capable of being handed off between operators and systems.

Stealth – Major stealth is not a requirement although it should have enough to allow it to operate in “lightly contested areas”.

The competing companies and their expected entries are:

Northrop (X-47B)
Boeing (Phantom Ray)
Lockheed Martin (Sea Ghost)
General Atomics (Sea Avenger)

The issuance of the current RFP to the four companies is intended to initiate a Preliminary Design Review phase of development after which a down-select will occur (bearing in mind that the down-select of the LCS never happened!) in late 2014.

The current RFP seems to suggest a very low level of capability compared to original concept capabilities.  The UCLASS seems to be geared towards surveillance and intelligence gathering with only a minimal, light strike capability.  This is quite a departure from the original concepts but seems eminently reasonable – gather actual operating data from simple missions and functions rather than trying to leap into capabilities that are beyond reach, as happened with the LCS.  I find this approach sensible and refreshing.


  1. 8,000 nm range is challenging for a UAS, but not infeasible. An MQ-4 can already do that (300 kts, 30 hrs aloft).

    I fully agree that Navy is being very smart in its approach to UCLASS. Requirements seem fairly conservative and achievable, and fill an important "gap" in carrier air wing -- long range ISR.

    1. Anon, I'm not an expert on the MQ-4 but my vague understanding is that it is 50 ft long with a 130 ft wingspan, or thereabouts. Scale that down to carrier size (say 35 ft x 80 ft, or so) and toss in a 3000 lb payload and I wonder if the range can still be achieved.

    2. Its probably doable, depends on how much they want to push the engine tech. Most of the designs are various forms of flying wings/lifting bodies so the lift to drag should be fairly favorable. Add to the fact that the engines on the MQ-4 are 20 years old (they were designed for the Citation X originally iirc), and you can probably get on the order of 10-12% fuel burn reduction using a more modern engine.

    3. Agree with ATS. Envisioning a carrier-sized aircraft which can provide MQ-4-like range/endurance performance isn't that unreasonable.

      But I'd add that when you're talking about system-level persistence, it isn't simply a matter or range and endurance. You also have to consider transit speed.

      A designer could theoretically "trade-off" speed for endurance - meaning that each individual aircraft doesn't have to stay aloft as long provided its relief can get on-station faster.

    4. If a MQ-4-like range is readily achievable, why hasn't it been applied to the Super Hornet and JSF, both of which are acknowledged to be a bit short-legged? Each are credited with a range of around 2000 nm. Why wouldn't they be 4000 nm or 6000 nm, at least? It's not just a speed issue; the MQ-4 has a cruise speed of 360 kts which is probably about what a Hornet or JSF does. I'm truly puzzled about what makes a manned combat plane have such a significantly smaller range. Is it wing area? If so, a carrier sized UAV would have the same limitations as a manned aircraft. Is it something else? Any idea?

    5. That's a tough question, so sorry if I ramble...

      Wing area is part of it. It's also the weight of the pilot, instrumentation, climate control, ejection seat and related survival equipment. All of that translates into weight and subtracts from fuel load.

      It's also design philosophy. An MQ-4 isn't designed to dogfight. It's very unmaneuverable and isn't equipped with an afterburner. It does one thing very well - stay in the air for a very long time.

      Both the Hornet and F-35 go a lot faster than 360 kts. An F-18 cruises at around 650 kts, and its military rated speed is much faster. An MQ-4 will only go 360-400 kts no matter what you do.

      A carrier sized aircraft could be designed for range/endurance, but you'll likely be sacrificing maneuverability. Which is probably OK, since an As which can outthink a human is still a long way off.

      I'd think UCLASS can and should be more like an S-3 than an F-18. Big emphasis on surveillance, little emphasis on strike.

    6. CNO, wrt to SH and JSF and range...

      The requirements and designers made explicit tradeoffs of range for flight envelope performance. There are significant differences between the engines used in an MQ-4 and a JSF or SH. In addition there is the massive gulf between sub-sonic, trans-sonic, and hyper-sonic.

      The engined used in jet fighters tend to be high specific thrust engines. This is required to maintain high levels of thrust at high sub-sonic velocities and allow thrust levels at super-sonic velocities. In contrast, a low specific thrust engine loses significant thrust as velocity increases.

      This also interacts heavily with the aerodynamics of the plane. Something like a commercial or private jet airplane relies on high lift/drag ratios and low specific thrust engines to maintain fuel economy. In contrast, military jets value maneuverability more than fuel efficiency and therefore have much lower lift/drag ratios and are generally aerodynamically unstable. They rely on high thrust at high velocity to overcome drag and maintain performance.

      For the roles that a UCLASS type jet is going to fill, Reinsurance and Strike, it really doesn't need the dynamic maneuverability or acceleration capabilities of a jet fighter. Being able to cruise at a reasonable mach .8-.85 and having commercial like acceleration should be sufficient. It isn't like UCLASS are going to be involved in a dogfight: the main regime where the performance trade-offs of dynamic instability, low lift/drag, and high specific thrust actually matter. So using a commercial turbofan with low specific thrust should be reasonable which will significantly lower specific fuel consumption (primarily from using engine power to turn a reasonably large fan).

      Just to explain specific thrust a bit more, an easy way to think of it is the velocity of the jet exhaust. At low vehicle velocity, a large cross section of low velocity exhaust provides a large amount of thrust, but as vehicle velocity increases, the differential between the vehicle velocity and the exhaust velocity narrows resulting in less thrust. With a high specific thrust engine, the cross section of the just exhaust is smaller but at much higher velocity, which means that the thrust lost as vehicle velocity increases is reduced.

      There actually is a lot of US government funding on adaptive jet engines primarily for military applications. And adaptive jet engine can vary both its exhaust cross section and its exhaust velocity in order to achieve the best of both worlds. During takeoff and lower velocity and/or endurance flying, the bulk of the engine power is derived from turbo-fan like operation. When higher speed and high speed thrust is required, the engine will transition into a turbojet like operation with a much smaller exhaust cross section and greater exhaust velocity but at the cost of fuel economy.

    7. ats, that's a great explanation. Thanks! I'll have to ponder it a bit more but it seems perfectly reasonable.

      One statement, in particular, caught my attention. You say the UCLASS performance (lack of speed and maneuverability compared to Hornet/JSF) is justified because it won't be involved in dogfights. Fair enough but the original intent was for an unmanned plane that could penetrate vast distances against very high threat defenses. It seems that a slow (350 kts), limited maneuverability aircraft would be unable to survive long enough to carry out its purpose. It would be, in essence, a target drone and an easy one at that. Sure, it has some stealth but that alone won't be nearly enough. If it were, we could used manned aircraft. Admittedly, the current specs for UCLASS seem intentionally reduced to only low threat environments and perhaps performance will someday be ramped up for the higher threat areas.

      Thoughts on this?

    8. Its not really that slow, we're still likely talking about a mach .8-.85 airframe which is effectively the same as what commercial air traffic run at.

      Realistically in the strike role, aircraft don't rely on their maneuverability to survive. First and for most is don't get shot at, you do that via a combination of jamming and stealth. Second is active counter measures if launched against: flares, chaff, burst jamming, etc. Last is maneuverability. And in general, you better hope that it doesn't get to that last phase. Even an F22, a Eurofighter, or a SU-35 is going to be hard pressed to out maneuver an anti-air missile that still has kinetic energy. It becomes a force/mass game at that point and the missile is going to win.

      If I was designing a UCLASS, I would concentrate on forward profile stealth, design it to be able to handle low altitude penetration, minimize its engine IR signature, and not rely on maneuverability for defense. Most of the time it will get out, but when it doesn't, its only money.

      Also, its important to remember what actual designed strike aircraft look like. The F15, F16, F18, and F35 were not designed as strike aircraft. They were designed as air to air fighters. The fact that they have strike capability is simply because both the airforce and the navy backed themselves into a corner without any actual strike aircraft.

      Examples of actual designed strike aircraft are the much misnamed F117 (an F designation without a gun nor AA missiles!), the A6, the also misnamed F111 (no gun and no AA missiles!), canceled A12, and to some extent the B-1B and B-2 bombers (they are primarily used for strike missions and not bombing missions). With the exception of the F111 and the minor exception of the B1, these are subsonic airframes. They all had significantly larger combat radii than their contemporary fighters and even significantly larger than modern jet fighters.

      They all rely on a combination of stealth, EW, low detection flying (aka on the ground), etc. None of them are particularly maneuverability by jet fighter standards, and none of them are going to out maneuver an AA missile or SAM. But they all had the capability to get the payload to the target at long range. Something that a warmed over fighter is never going to be able to do.

  2. Copied from the General Mattis thread:

    Scott Brim August 10, 2013 at 10:57 AM said:

    An RFP for UCLASS was released earlier this summer. My initial impression that the scope of the original concept has been severely reduced is confirmed by the article.

    This is not good. Over the next two decades, the survivability of manned aircraft over a highly-contested land battlefield will come increasingly into question, and the evolutionary development of unmanned strike aircraft will become increasingly more important.

    This will be an expensive and time consuming proposition, especially the artificial intelligence development efforts, but it has to be done if airpower is to maintain its long-term value as a national strategic asset.


    ComNavOps August 11, 2013 at 10:52 AM said:

    Scott, you are undoubtedly aware that the historical record for surface to air missile effectiveness is pretty poor - on the order of 1% to, perhaps, 20%, at best, per launch. There is no reason to believe that will change significantly in the future. You may argue that missiles and radars are getting better but then you have to allow the opposite side, that countermeasures, stealth, jamming, anti-radar missiles, etc., are also getting better. In fact, an argument can be made that SAM effectiveness will decrease in the future. The point is that we are just speculating - there is no evidence one way or the other to assert that survivability of manned aircraft will decrease.

    Even if survivability decreases, it will decrease for UAVs, as well. As UAVs get more expensive, their rationale for use will decrease (other than the saving of pilots lives which is a huge benefit!). No one knows the costs but, presumably, a UCLASS that has performance specs that approximate (or beat) a JSF will cost around what a JSF costs. If so, there's no real advantage to the UCLASS (other than the pilot's life, again!).

    I'm quite dubious that UAVs are going to be the magic panacea that we all believe.

    See my response below:

    1. ComNavOps, it is my opinion that over the next four decades, highly networked and integrated A2/AD systems combined with advanced IAD systems which include laser battlestations, massive sensor capacity, and massive information processing horsepower will gradually gain the upper hand over aircraft, manned and unmanned alike.

      The process will be gradual, to be sure. UAV's will buy some time, but by mid-century, 2050 or thereabouts, the advantages that a capable adversary's defensive systems will have over aircraft operating above a land battlefield will be complete.

      Not to say that victory against such a capable adversary in some particular engagement in some particular battlespace over some particular land battlefield will become impossible.

      In that kind of scenario, stand-off weaponry will play a significant role in preshaping the battlespace. The assault begins with a massive barrage of stand-off ordnance types, followed by UCAVs followed by manned aircraft. Armored land forces attack simultaneously and place their own pressures against the centers of A2/AD and IADs resistance, with the armored land forces supporting the aircraft just as much as the aircraft are supporting the land forces.

      A conflict with a capable adversary in the year 2050 will be a wild maelstrom of combat action. In that kind of Big War scenario, it is easy to predict that the price of victory measured in human and material casualties will become extraordinarily steep in comparison with what we think of today as being acceptable losses.

      The upside of strike UCAVs is that they will have greater maneuverability and greater endurance while operating inside the most dangerous parts of the battlespace, and they won't risk a human pilot. The downside is that it will take decades of work and a whole lot of money to slog through the arduous process of developing some practical combination of reliable UCAV artificial intelligence capability and secure UCAV C&C data communications capability.

      If we look strictly at the airframe as something apart from its AI software, a UCLASS airframe which could do everything the F-35 airframe will eventually be able to do -- and more, or so I personally think -- would be easy enough to develop and field. The fundamental issue lies in how much time and money it will take to develop the AI software, the secure UCAV data communication links, and then a CONOPS for the aircraft which can make effective use of whatever the future AI software and data communications network can deliver.

      Pure speculation on my part here, but upon further reflection, it could be that the USN has looked at what it will take in time and money to get the AI software and the C&C network architecture well enough developed to properly enable a full size UCAV, and has decided to wait until that very complicated and expensive software is further along.

    2. Scott, that's a very nicely written and well reasoned piece! My only rejoinder is, as I suggested before, that you're giving full credit to the defensive side of the equation without allowing for similar benefits, gains, and capabilities on the offensive side.

      I could imagine supersonic/hypersonic UAVs, hyper-maneuverable UAVs (since they're unmanned - current maneuverability is limited by pilot G-force tolerance), UAVs that fly literally 10 ft above the ground (who cares if one crashes?) to reduce exposure to near zero, adaptive stealth surfaces, refractive (invisibility) aircraft surfaces, hugely more effective electronic countermeasures thanks to massive information processing horsepower, etc. All of that backed by standoff support aircraft using airborne laser weapon stations to instantly shoot down any SAMs or enemy aircraft and hypersonic anti-radar missiles or lasers to degade enemy sensor capabilities. And so on ...

      The point being, again, that you have to give credit to both sides of the equation.

      The equation and the results of the equation have held true since the start of WWII despite the fact that technology has improved by immense leaps over that time period. It's just as hard (and the kill probability is just as low) to kill an attacking missile or plane now as it was for a ship to shoot down a plane in WWII. The technology has changed but the results haven't.

      Will one side or the other of the equation gain an upper hand? I have no idea but until I see some definitive evidence of a change I'll stick with historical results.

      That said, you've written a great comment with lots to think about. Thanks!!!

    3. ComNavOps: "The point being, again, that you have to give credit to both sides of the equation. ..... Will one side or the other of the equation gain an upper hand? I have no idea but until I see some definitive evidence of a change I'll stick with historical results."

      In predicting which side or the other of the equation will eventually gain the upper hand, and viewing the situation from a technology management perspective, I give the defense a slight edge at this point in time, but one that will slowly grow as the decades pass.

      The defense holds the initiative in determining the costs the offense must pay in order to achieve victory. The defense holds that kind of initiative both during a combat engagement and also prior to the engagement in forcing a potential adversary to expend ever more resources in developing and fielding the systems and the force structures needed to overcome the ever-evolving defenses.

      We are seeing a prime example of that situation with the F-35 program and its history over the last fifteen years as a highly complicated and expensive technology management endeavor.

      The performance specification for the F-35 is now more than a decade old, and two decades will have passed before the performance capabilities specified a decade ago will actually be fielded. In the meantime, the A2/AD threat and the IADS threats are still evolving, and will continue to evolve.

      But the costs of achieving those capabilities for the F-35 is massively higher than was originally predicted a decade ago, and the result will be many fewer F-35 airframes purchased -- my guess on that score is roughly a thousand airframes in comparison with the 2800 that were supposed to be produced under the original cost estimates from 1995.

      The true cost of the F-35 program is driven by a performance specification heavily influenced by an ever-evolving A2/AD and IADS threat environment.

      The technology development issues of countering that evolving threat environment, combined with the fundamental mistake of attempting to build the STOVL version as a variant of the other two airframes, will have had the long-term effect of shooting down roughly 1500 F-35 airframes before they were ever even constructed.

    4. Scott, you state that the defense holds the initiative in determining the costs the attacker must pay to achieve victory. I understand your point but I disagree, at least in many instances. For example, IEDs (roadside bombs) are the attack and they are cobbled together for a hundred dollars of spare parts while the Army is spending hundreds of millions of dollars defending against them. On a much higher tech level, the Chinese claim to have developed a carrier-killer intermediate range ballistic missile. The mere threat of that has forced the defense, the Navy, to spend billions on BMD. I'm guessing the Chinese missiles cost several hundred thousand or a million dollars each - cheap compared to what we're being forced to spend on defending against them.

      I can go on with examples but you get the idea. Your point is valid - one side has a cheap option and the other side has to pay heavily to overcome it. However, it's not always the defense that has the advantage.

  3. Funnily enough, I ended up having a discussion which might answer your first point, re: orbits, a few months back in the comments section of this post:

    In short, apparently 'orbit' has a different definition in naval air circles than it does for the rest of the world, and doesn't mean 'a flight in a circle around a fixed point at a specified range'. Apparently.

    1. Orbit has been used by the Air Force to describe its UAS force structure for quite some time.

      Navy has also adopted similar terminology to describe BAMS/TRITON.