Thursday, February 25, 2021

Fire Scout ASW - Promise and Challenges

Northrop Grumman (NG) recently conducted an internal test of an ASW (anti-submarine warfare) configured Fire Scout MQ-8C UAV (actually, a modified Bell 407 simulator of the Fire Scout) in Oct 2020.  The test was declared a success (it could have crashed on takeoff and it would have been declared a success – that’s the way these staged tests work) but the real point is that after years of commentator speculation about the benefits of UAV ASW, someone finally made an actual effort, regardless of the real degree of success or failure.  Yes, I’m aware of the 2017 MQ-9A sonobuoy tests but that was sonobuoy integration testing, not ASW testing. 


Moving on, let’s take a closer look at both the promise and challenges of UAV ASW.


A NG spokesman claimed that the Fire Scout could operate 100 miles from the host ship and with up to 12 hours endurance.(1)  Concept art and verbal descriptions depict a Fire Scout with two sonobuoy dispensers holding a total of 40-48 miniature sonobuoys although testing was apparently conducted with a single, smaller, sonobuoy dispenser.


Artist's Concept of ASW Fire Scout


Some advantages of an unmanned ASW platform include:


Extended Range/Endurance – The MQ-8C can, under the right conditions, extend the ASW range from the host ship and, again under the right circumstances, the endurance of the ASW effort.  The Navy/manufacturer claim 100 miles and 12 hours endurance, however, those are predicated on minimal loads and minimal sonobuoy usage – hence, the ‘right conditions’ and ‘right circumstances’. 


If the payload increases (carrying torpedoes, for example), the range and endurance drop dramatically.  NAVAIR lists endurance as 12 hours with a 300 lb payload (2) although this is somewhat misleading since transit time has to be accounted for (an hour out and an hour back, for example, at the 115kt cruising speed(2)).  Throw in reserve fuel/time and the endurance is further reduced.  Add heavier payloads – like a 600 lb Mk 54 torpedo – and endurance will drop drastically.  Still, several hours of loiter time is potentially useful and impressive.


Far more importantly, if the sonobuoy usage is heavy, the endurance becomes meaningless.  Once the sonobuoys are gone, the helo has little else to do but return to the host ship.  Yes, it can hang around and listen for a while but with no active contact, that would be largely pointless.  If sonobuoys are dropped in strings of, say, 5, a Fire Scout with 40 sonobuoys would be able to lay only 8 strings.  In a combat scenario, where every slight sonar twitch demands investigation, 8 strings would be used very quickly.  One might recall that S-3 Vikings, acting in the extended hunting role, tended to deploy sonobuoys in chevrons resulting in heavy sonobuoy expenditure.  Assuming a Fire Scout would behave similarly, sonobuoy depletion is an issue.  Thus, endurance is probably a misleading and meaningless claim. 



There are also some potential challenges to unmanned ASW which include:



Weapons – Currently, there are no plans to put weapons on an ASW Fire Scout.  This makes the Fire Scout only partially effective and requires two platforms (a second, weapon carrying platform) to perform the function of a single manned helo or P-8.  The lack of weapons also means that the Fire Scout will have to maintain contact until another platform can arrive which is no easy feat.


Communications – Operating at a range out to 100 miles puts the Fire Scout well beyond line of sight communications.  It will either have to climb to higher altitude to maintain communications or depend on some kind of satellite communications or other methods which are less likely to be available in combat.  This also raises the issue of the communications broadcasting the helo’s location.  The communications requirement to transmit the kind of data intensive packages involved in ASW detection and tracking – and from multiple sonobuoys! – is enormous, I would assume (not being a combat communications expert).  Add in the requirement that the data be near real time and the comm load is immense and continuous.  This just screams out detection of the Fire Scout.


Not to be ignored is the control communications link.  UAVs have a disturbing tendency to lose command link and wander off, never to be seen again.  There will be a certain degree of attrition attributed to command link loss.


Off-board Processing.  The communications discussion leads directly to the issue of off-board data processing.  Unlike the old S-3 Viking, SH-60 type helos, or P-8s which have sonar analysts aboard the aircraft, the Fire Scout will, of course, be unmanned and data processing will have to occur aboard the host ship.  This causes the communication issue just described and introduces a degree of lag between the Fire Scout and the host ship.  Of course, ASW is, generally, a pretty slow affair so this will likely not be a severe problem.


Payload – Fire Scout is a small helo and payload capacity is uncertain but limited.  I’ve seen widely varying claims but NAVAIR lists the payload as 700 lbs (2).  By comparison, a Mk 54 lightweight torpedo is around 600 lbs.  NG demonstrated a very small, very lightweight, 220 lb torpedo drop from a Bell 407 in 2016.(3)  Of course, it’s highly questionable whether such a small torpedo would be effective against a submarine given that our largest, Mk48 torpedoes, were deemed to be of questionable lethality against Soviet Union submarines.  Smaller diesel subs, less stoutly constructed, might be hindered by such a small torpedo but that, too, is questionable.






We see, then, that unmanned ASW potentially offers benefits for range and endurance but those benefits exist only under certain conditions and are potentially offset by the challenges such as limited payload, communications, lack of weapons, and off-board data processing.  The ability to potentially push the ASW outer layer further away from the host ship is useful and, to a limited extent, makes up for some of the capability we lost when the S-3 Viking was retired without replacement.


The major challenge seems to be the lack of weapons which means that any prosecution requires two aircraft to equal a single Seahawk or P-8.  The ability of an unmanned aircraft (or any platform, to be fair!) to hold contact on a submarine for an extended period until a weapon carrying platform can show up is highly suspect.


On balance, I’m not seeing sufficient justification for an unmanned ASW Fire Scout to replace a full size Seahawk helo.  Now, a very small, UAV carrier with a bunch of Fire Scouts might well be a useful addition to any naval group and this is the developmental direction I’d explore. 





(1)USNI News, “Northrop Grumman Pitching Fire Scout Helicopter Drone for ASW Missions”, Sam LaGrone, 16-Feb-2021,




(3)The Drive website, “Northrop Grumman Reveals New Mini Torpedo Aimed At Arming And Defending Navy Submarines”, Joseph Trevithick, 21-May-2020,


  1. What's the price for one of those?

  2. Off-topic, but relevant to the wider mission of the site: USAF has concluded F-35 is not a suitable replacement for F-16.

  3. The lack of weapon issue may be solved with a longer ranged ASCROC (if your comms are good enough to send live acoustic signals, they sure are good enough to have some king of CEC for underwater weapons) ...

    BUT : there is a cost/benfit analysis to be made, you save weight on the UAV by taking the weapons away so it cheaper to operate, but does the increased cost of the weapon itself cancel all this ?

    BUT : it all relies on the comms, cf your previous post.

    So overall big doubts.


    1. "longer ranged ASCROC"

      The current VL-ASROC has a range of 11 miles. Jumping that to 100 miles is a huge step! Possible but cost, cost, cost!

  4. Think the sonobuoys shown fitted with Ultra Electronics 4 kg miniature sonobuoys, so substantially smaller than standard sonobuoys with smaller batteries and so have much shorter active operational life when in sea, assume you need one active sonobuoy pumping out ~200 dB?, with for four or five passive sonobuoys to listen for any returns and so able to triangulate subs position.

    No mention if fitted with a yet to be developed automatic AI Multi-Static Active Coherent (MAC) System? to process data from sonobuoys, otherwise need to transmit all data to the mother ship MAC

    Think NG funding development of the VLWT based on the 2018 cancelled carrier CAT, countermeasure anti-torpedo, suggestions variation of CAT may be installed on Columbia and new Virginia subs to target enemy torpedo attack.

    No mention if fitted with a lightweight dipping sonar, the MH-60R fitted with the AN/AQS-22 Airborne Low Frequency Sonar (ALFS) its primary undersea warfare sensor.

  5. Wow, lots to cover here.
    - In the renderings this sonobuoy system always uses the pass through the cabin pylon system for the Bell 407. Is that even possible in MQ-8C? Will doing so remove a gas tank? Is this why they used the manned platform to test?

    - When the brochure for the UE dispenser was on line it specified a 60lb on board data processor. The pods themselves 369-413lbs depending on type of sonobuoy used. Obviously this blows the numbers for anything this airframe has carried right out of the water. A good comparison is the fact an APKWS and a type A sonobuoy weigh about the same. By that logic this platform would be limited to about 14 buoys.

    - Weapons - Jane's indicates the roadmap in an article yesterday. They are pursuing CVLWT officially. I would love that to turn into a quad packed future VLA. They also lay out the plan to operationalize HAAWC with the current Mk 54. It then lays out Mk 54 mod 2 which can't be used with HAAWC or VLA. Makes me think statements made a few weeks bacck mean there is a new VLA now under development and is not yet public. TBD.

    1. The Mk54 light weight torpedo has a 96 lb warhead and the torpedo is twice the size of the VLWT so, presumably, the warhead on the VLWT would be around 45 lb or so. Is that enough to do worthwhile damage to a sub?

    2. RBU-6000 has a 43 lb warhead.

    3. Per The Drive, the "new VLWT is based is only six and three-quarters inches in diameter, around 85 inches long, and at just around 220 pounds." Compared to the Mk 54, the VLWT is about half the diameter (6.75 vs 12.75 inches), about 20 percent shorter (85 vs 107), and about 1/3rd the weight (220 vs 608). If diameter and weight are the primary factors, the warhead is likely smaller, maybe in the 30 lb range.

      But, the VLWT were designed to defeat other torpedoes, an underwater version of SeaRAM, as it were. They probably have decent speed, but I can't imagine they have much range if they're only trying to hit a torpedo coming at you. You might hit a sub if you dropped one right over it, but I think you need a bigger torpedo.

  6. So we've basically taken a JetRanger and removed the pilot. What does all the remote control gear weigh? What was the payload capacity of a standard, off the shelf JetRanger?? And what did they cost?? Considering the long history and production of that platform, wouldnt we be better off with a piloted version that can carry some weapons?? At least one standard torp, or a couple lightweights (the choice there is another discussion)?? Maybe a cheap JetRanger with pilot and weapons built en masse might be a better route(??) Sure we already have Seahawk, but Im sure they are significantly more expensive. Maybe an ASW JetRanger could bolster the helo numbers, as a less capable but cost effective addition?? Maybe not,I honestly dont know, but it seems like theres a lot of expense and effort here, with little return, just to be "unmanned"...

  7. Bring back the S-3, or some updated replacement. Taking the S-3s off is one big factor in the decreased in size of the carrier wing. Nimitzes hauled them around before, no reason they can't again.

    Have a squadron of 12 per carrier air wing, 6 for ASW, 5 for tanker, 1 for COD.

  8. The USAF is now making noises about dumping the F-35 and getting a different plane.

    They're also considering nationalizing the military plane industry.

    I look forward to your upcoming post(s) about this!

    1. I don't follow Air Force matters, per se, but I have seen no explicit announcements on either of those topics. Do you have a reference?

    2. "nationalizing the military plane industry."

      As I said in the previous comment, I've seen no such announcement. That aside, what do you think of the concept? Would a nationalized aircraft industry be a good thing? Given the decrepit, deplorable state of the Navy public shipyards and the immense backlogs of maintenance work associated with them, is there any reason to believe that a military aircraft industry would perform well?

    3. Well, *replace* is perhaps too strong a word. What the USAF is looking to do is replace the F-16 with another plane that is not the F-35. The F-35 was intended to replace the F-16, so this new airplane will replace unbuilt F-35s.



      (if you do a search for "F-35 replacement" you'll find a bunch of reporting on the subject)

      Nationalizing the military plane industry:

    4. And my apologies for not seeing your question!

      I see the USAF's moves to nationalizing the military aircraft industry as a disaster waiting to happen. The government can make small successes in-house: think of how influential China Lake has been in terms of military technology.

      When it comes to widespread military procurement, it'll be slower, more expensive, more corrupt, and 100% politicized.

      As you said, the military can't keep its own existing infrastructure running effectively. There's no reason to think that the USAF suddenly had an epiphany and will somehow not screw us all over.

      As I read through that article in horror I couldn't help but think of the Mark 14 disaster from WW2.

    5. "nationalizing"

      Okay, thanks for the link. It's not quite a case of the Air Force talking about it … it's one guy, in the procurement side of things, warning what the extreme outcome might be if the existing industry further contracts. Here's the relevant quote from the article:

      “If our industrial base collapses any more, we'll have to nationalize advanced aviation and maybe other parts of the Air Force that currently are competitive,” Roper said."

      That does not sound, in the least, like any active, sanctioned, discussion of nationalization. That said, the guy's warning is perfectly valid and I've already addressed how to maintain the industry with more competition and producing cheaper aircraft, faster.

    6. "The F-35 was intended to replace the F-16, so this new airplane will replace unbuilt F-35s."

      Ah, that's stretching and twisting the logic a bit. Yes, the AF is looking into the possibility of building a new, lower end (hence, F-16-ish) aircraft. You have to go through some logical gymnastics to get to a new F-16-ish replacing the F-35. That's not at all what the articles or the AF thoughts suggest. The new F-16-ish seems to be more of a complement or addition to the F-35 buy rather than a replacement for it.

    7. "“Technical talent is at a premium,” he said. “If the design opportunities are so few and far between that joining a defense company means you may get to design one thing in your career ... — and that's if you're lucky — that that talent will go elsewhere into commercial innovation where the opportunities are more plentiful.”

      Roper’s project envisions developing and buying plans at a much quicker rate than traditional tactical fighters which often take a decade before they are produced in large quantities. By that time, technology is already dated and brand new planes must undergo costly and time consuming upgrade projects."

      At least this Roper guy understands the situation!
      Good for the Air Force, if they listen to him.

    8. Navy dislike F-35C because it is a single engine fighter. Navy usually choose twin engine fighters for safety because there is no back up landing platform in open sea.

      Other issues both Air Force and Navy have concern:

      F-35 is stealthy thus can carry much less weapons - internal weapon bay has limited capacity.

      F-35 is the slowest air superiority fighter in US. Initially, F-35 was designed as attacking fighter to compliment F-22 but heaps of problems of F-22 itself caused that program ended. Do you believe the official reason as "too expensive"? think about DDG-1000.

      F-35 fails to deliver low running cost. Maintenance costs are much higher than planned. Businesses can usually tolerate high capital investments but not high running cost.

      Ironically, Air Force moves toward Chinese model - J-20 supported by advanced 4th generation fighters (J-16 and J-10). J-20 has no gun. Its mission is to use its stealth to open up enemies' line and then J-16 conduct following attacks.

      Now, Air Force wants more F-15 and Navy actually wants to maintain F/A-18, both can load lots of weapons.

    9. "Navy dislike F-35C because it is a single engine fighter."

      I don't think that's the reason. While safety may be a factor, I think it's a fairly minor one. The Navy has operated single engine aircraft before. The A-4 and A-7, come to mind. Dual engines probably has more to do with obtaining the requisite thrust in a manageable package than redundant engine safety.

      The Navy's ambivalence towards the F-35 likely stems more from not seeing it as an ideal fit for the anticipated role and recognizing that it's a very expensive option for a marginally adequate role fit.

      In addition to the immense direct costs of purchase price and operating costs of the F-35, the Navy is also incurring massive secondary costs to modify carriers and amphibious ships to operate the F-35. It is apparently costing tens to hundreds of millions of dollars to modify flight decks, rearrange underlying compartments, add additional soundproofing and thermal protection, add new communications and data processing capabilities, add a second parts storage and workshop facililties. etc. Finally, there's the tertiary logistics cost in establishing a new parts train, depot support services, etc.

      Cost and suitability are the Navy's concerns far more than the safety aspect.

  9. Do you think it would be possible to lob a sonobouy out of a mortar to a useful distance? Or better yet out of a 5 inch gun. If you can punch out sonobouys to useful distances that should help no matter whether you are using manned or unmanned systems.

    1. Given that submarines are effective out to a hundred miles or more, depending on weapons and circumstances, what do you think a 'useful distance' would be? Passive sonar operates with convergence zone distances which means something on the order of 20-100 miles so 'useful distances' would seem to be the same. Do you think we're going to get 20-100 miles ranges from a 5" gun?

      Also, the usefulness of sonobuoys depends on laying them in fairly precise patterns. Do you think we can produce such precise patterns by firing from a 5" gun over 'useful distances'?

    2. Don't no if we could. It was more a question than an answer.

    3. Current sonobouys are fairly lightweight and cheap, which is just as well, since they get used in large numbers.

      Making a machine whose job is to detect faint sounds robust enough to survive being shot from a gun and then falling from a high trajectory into water sounds hard. I bet some contractor would be willing to try, but it sounds like a fine way to make them far more expensive, less reliable and less sensitive.

    4. "It was more a question than an answer."

      Fair enough. Nothing wrong with a good question!

      I note the problems the Navy had trying to get the Zumwalt's LRLAP munition out to 100 km (they never did!) so this would be a challenge!

  10. I really think a carrier based sea Guardian if the fastest path to useful at this point. Or better yet, Navair really gets a game plan for UAVs on deck aside from a gas tank. In the world of vertical UAV, what the world could use from the logistics vantage point is a single engine platform that uses a T700-GE-401C

  11. Sonobuoys are very effective of finding submarines, especially in shallow waters. Active sonobuoys can "torture" crews in submarines as their sounds are really really really anointing. Place large number of sonobuoys in shallow waters (say, less than 200 meter deep) can make submarines unable to operate in very large areas. Downside of sonobuoys is they are one-use consumable.

    UAV and P-8 can only operate in areas where enemies have no control of skies. In war time, this means that if an enemy has local air superiority, than neither UAV nor P-8 can safely launch sonobuoys and stay nearby to listen signals from these sonobuoys.

    1. Effective at finding submarines, or effective in localizing submarines?


    2. Sonobuoys can find, locate, and track submarines. They are very effective in shallow waters (roughly say, less than 800 feet deep). Unlike sonar mounted on ships which provide background noise, sonobuoys are quiet. While use active mode, they act like radars. They use GPS or Beidou to locate themselves and report suspected objects' locations.

      Advanced sonovbuoys have made submarines unable to survive in shallow waters. This means submarines cannot approach coast with large body of shallow water next to it.

      Downside is that they are one-use consumable. Also, there are not many nations have this kind of technologies.

  12. " Now, a very small, UAV carrier with a bunch of Fire Scouts might well be a useful addition to any naval group and this is the developmental direction I’d explore. "

    Another area the LCS failed. Imagine a robustly built Indy Class. Could handle....3 UAVs? And there are so many LCS.


    1. After the Gulf War and Soviet Union collapse, US Navy thought that they will not face any enemy in open sea. What they need to do is to support land invasion. Under this thinking, LCS, DDG-1000, ... etc. were made to suit this strategy.

      As China rises, the whole thinking has become strategic mistake. Navy has found that it overlooked fighting another capable fleet in open sea. This makes Navy re-think on what next. Constellation and DDG(x) are proposed but already too late. Weapons work on weak nations usually don't work while face China.

      However, how to react to Chinese navy is another topic which cannot be written in such a short comment.

  13. Another iteration of unmanned fad. What I see is an inferior platform in everything except endurance.

  14. and purchase cost and maintenance costs.

  15. The Chinese concept is closer to what you describe. They have a 1100 lbs unmanned ASW helicopter that will supplement manned ASW helicopters.


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