Maritime Patrol Aircraft - Best/Worst Features
 

Evening all!

I've been assigned a Uni Project, with brief to design a clean sheet Maritime SAR / Submarine Hunting aircraft. I thought this might be a good place to canvas some opinion on what makes a good aircraft for that role. Hence my question for those who have designed / built / flown / worked on / maintained any fixed wing Maritime Patrol aircraft (P-3, P-8 & Nimrod spring to mind) :

What are the best and worst features of these aircraft? Design features & capabilities that you admired and things that made your life difficult while working on them?

I'd really appreciate any input, whatever your link to the aircraft, so thanks in advance if you can contribute.

Cheers, RR

There must be literally 20 odd threads on here about MPA already. Have you had a look at those? Try a search for 'MPA replacement' 'Nimrod 2000' 'P8' 'tea-pots' (the last one will surprisingly also be about MPA...)

Why only fixed wing?


SAR and ASW roles are also heavily fulfilled by rotary wing aircraft.


Your title says MPA but your brief states SAR and ASW, whilst MPA do SAR and ASW actual recovery of persons from the water and generally detection and prosecution of submarines in the vicinity of the fleet are generally (for the UK specifically) conducted by rotary wing aircraft.

Sandy, so will any search for kipper, dairy cream sponge or fray bentos pie.

Come to think of it, just make up a random search and you are bound to find a MPA thread tenuously linked somewhere :ok:

Best/worst depends a lot on what the airplane is expected to do, and different nations have very different requirements/expectations. But I would guess that having engines buried in the wing root like the Nimrod, while not a "worst" feature, would definitely be a feature to avoid.

What, no love for the Atlantique 2?

Hey Op,

I'll take pity on you, seems no one is interested. I have 5000 hours flying on MPA (mostly, but not all Nimrod)

Assuming your spec id for long range maritime patrol, also known as blue water ASW.

Range/Endurance - The ability to transit long distances and loiter on patrol.
Speed - to get on patrol relatively/reasonably quickly.
Capacity 1 - to carry weapons, sonobuoys and other ordnance
Capacity 2 - to carry a largish crew
Capacity 3 - to carry a full sensor fit (radar, acoustics and other stuff)
Capacity 4 - to carry a load of communications equipment (LF, HF, V/UHF, Data Link, Satcomm etc)
Aircraft Systems - needs to have electrical capacity to drive all this kit and the cooling capacity to stop it overheating. Needs system redundancy to keep the thing operating at a consistent level. Needs the ability in terms of engines, handling and avionics to operate at low level over the sea for very long periods.

that should get you started.

Other aircraft types, smaller a/c or helos as mentioned can do shorter range stuff, but at this moment in time only fixed wing large aircraft can do long range maritime patrol.

Technology might change this one day, but it aint' here yet or even close.

PS and yeah, to keep everyone happy..it needs a galley.

It all flows from the Mission - define the mission, derive an operating concept, derive operational requirements, which lead to user requirements, which lead to system requirements that lead to system features. The actual aeroplane isn't at the top of the operational hierarchy - it comes a couple of steps down the tree. The following comes from a paper on the subject which started from the premise that:

"Engineering could be described as the field of endeavour associated with devising systems that provide a capability to undertake a mission"

Where “Systems” would be any combination of machines, people, skills, infrastructure and information, a “capability” would be the ability to utilise the system when required for its intended purpose and a “mission” is some activity required to meet a political or economic need, either as discrete events or a continuous activity. From this flows a view that can be visualised as a "mission pyramid":

http://i925.photobucket.com/albums/a...omposition.jpg

The problem with trying to jump straight to the systems requirements stage is that you can't establish the root justification for each requirement in terms of how it contributes to (or enables) mission success. They just become rabbits pulled from a hat, and that presupposes that some has actually put some rabbits into the hat in the first place.

HTH,

PDR

Good thread for an intelligence service to start in the hope that someone will, inadvertently, provide a useful snippet or three.

....and not forgetting the toilet capacity!

Galleys, toilets, and other crew amenities assume a large blue water patrol aircraft. But for some nations, a small austere twin, like a King Air 350LR, may the "best" feature. Even for a big and rich nation like USA, a medium turboprop twin may be ideal. Witness the US Coast Guard taking over the C-27Js USAF parked in the desert. And for a few decades a medium twin jet, the S-3 Viking, was the "best" way to go. Again, "best/worst" is totally dependent on the mission and absent a rigorous mission definition, "best/worst" cannot hope to be defined.

Mission (mis)definition is the trap the "F-35 cancelled" thread fell into for the first several years it ran. The airplane's mission was completely misdefined and misunderstood by the countless trashboys in that thread.

Carefully considering all the comments here, after operating P3B and P3C Update 2.5 airplanes for over 10 years (5,000+ hours), I think they are the 'ducks gutz', and I'm very disappointed Lockheed didn't go on with producing the P7.

While PDR's top down systems engineering approach is sound, don't forget the constraints eg the cost/price. Most MPAs start with an existing platform as it's likely to be the most cost-effective approach. Pick your platform with care as this will probably be the most important constraint.

EAP

The question pre-judges that the solution is actually an aeroplane - there's no particular reason why it has to be and artificially constraining the options too early in the process is rarely a good idea.

For example a requirement that calls for “a bridge capable of handling 500 cars per hour in each direction” would allow bidders to offer a suspension bridge, a box-girder bridge, a pontoon bridge or indeed any of many other technical approaches, but all of them must be bridges.

A requirement calling for a “river crossing capability for 500 cars per hour in each direction” would allow all of these, or a tunnel, or a ferry service, or a catapult-and-net system. It might even allow an enterprising contractor to offer a service-based solution using a fleet of surplus heavy-lift helicopters that he happened to see coming up on Ebay with 1 minute to go, no bids and a £0.99 minimum bid price. That could achieve the requirement with a totally different financial profile (minimal capital, higher revenue) whilst also adding the benefit that it could be in operation in a matter of weeks with no construction disruption rather than needing five years of construction investment and constipating of local traffic for the duration.

Focus on the mission first - never prejudge a solution. Some maritime patrol requirements can be fulfilled with remote video camera with a zoom lens. That solution wouldn't need a galley or a toilet...

PDR

My suggestion is also a 'role bay'. An area that can quickly be reconfigured to take a crate/pallet of auxillary equipment that can adapt the role of the aircraft quickly. When not in use the role bay could be fitted with Pax seats or a small rest area with a couple of bunks.

In addition make the aircraft maintainer friendly for example trim that is easy to remove and refit.

O2 on tap for all to alleviate the Kokinelli headaches.

PDR1 - my argument against Concorde (don't get me wrong, a brilliant aeroplane in whose building I played a small but proud part) - but if the objective is to get from city centre to city centre as quickly and economically as possible, Concorde was just maybe the "wrong" answer

Absolutely - for journey distances much below about 5,000 miles, anyway. It's like putting out requirements for ever faster carrier pigeons when someone is selling telephones!

I once read a Fast Jet URD which included the phrase "the aeroplane must be able to retract its undercarriage".

A few seconds of thought and you realise that this isn't a requirement at all - it contributes nothing to the mission objectives. It's actually a system solution to the operational requirement:

"Shall operate from CVS-class carriers"

and the performance requirements

"Shall deliver death, mayhem and Xmas presents to a target 500 miles away within 80 minutes of mission tasking"

"Shall have a mission radius (with reserves) of at least 800 miles"

and the operating constraints:

"Shall fit down a standard CVS lift"
"Shall fit in a standard CVS Hangar space allocation" [yes I made this up to keep it simple]
"Shall not require external refuelling support to achieve standard missions"

Within these constrains and requirements most of the available solutions will use a wheeled undercarriage, and it's highly unlikely that the drag of a non-retracting undercarriage would be tolerable. So the undercarriage is a system solution, not a requirement.

QED

PDR

Not sure of your involvement with P7, but that program had sufficient warts on it that it deserved being cancelled (in part due to some dodgy claims LM made). Not saying the aircraft necessarily should have been, but sometimes (see also A-12) the program kills itself.

Thanks for the feedback and tips so far

No need for actual recovery in this case, more the "S" part of SAR

I'm looking at long range missions, so fixed wing is probably the only way to go. In any case it's an artificial constraint of the project, so fixed wing it is!

Im particularly interested in the advantages (if there are any) that going for a clean sheet design might offer. Was there anything that the Atlantique (or the Kawasaki P-1 if anyone has any experience) is able to do better than the MPA's adapted from airliners?

Ahem, the most important.....
 

.....component of any new MPA/MMA must be a well trained crew. Not just the execs but including all the equipment operators. They should operate together and not in little cells.
One of the worst phrases I ever heard was "Aft of the flight deck door is mission crew ****"

The Ancient Mariner

AM'

No doors on Shacks'. It was the ability to hurdle the Main Spar at speed which improved Fore' and Aft' communication'.

AD

I too operated P-3C for some years. In addition, I participated in the LRAACA program which was intended to replace the P-3. Douglas proposed a UHB powered MD-80 derivative, Boeing proposed a 737 derivative, and Lockheed proposed a P-3 derivative. After Lockheed won the contract, the Navy redesignated it P-7A. The P-7 had LOTS of problems, not the least of which was that Lockheed had based their proposal price on the estimate that the new airframe would be 80% or more common with the old one. As it turned out less than 2% was common, costs spiraled, schedules ballooned, and USN terminated the program for default.

Lockheed proposed a much more ambitious Orion 21 for the MMA RFP. But Boeing won that contest with a 737 derivative which became the P-8. Lockheed tried to market Orion 21 internationally and even offered bits and pieces of Orion 21 as P-3 upgrades, but got scant interest and no orders.

What machine?
 

I spent some years playing with the Searchwater radar in a Viscount and so have some interest in the project

Naturally we are concentrating on winged types but there are others

Long loitering lighter than air vehicles might be worth a look as are satellites

In general satellites are not considered capable of delivering payloads to the surface but in the early days photo packages could be dropped

:ok:I believe the French are renovating the Atlantique for another 30years' life. That is what we should have had to replace the Shack, we could have had twice as many for less than half the price.

Croqueteer, the advantage that the Nimrod had over the Shack, and by extension the Atl, was a high transit speed enabling it to reach a patrol area 1,000 miles out in about 2.5 hours compared to double that in a Shack. Faster transits enabled fewer airframe to maintain a patrol box.

On patrol the Atl speed would be around 190 kts compared with around 225 for the Nimrod. This enabled either a faster revisit time or a larger patrol area for the same revisit time.

However our boss at the time opined that the floor level on the P3, and by extension the Atl, was better as it was lower allowing more room for the crew at waist level (no cracks about the galley) for moving about.

British Radar
 

When we first saw the Searchwater at RAE RRs it wasn't that great, I once saw Wolf Rock logged at doing 20 knots but improved rapidly and when it was released I understand crews were v happy with it

Thanks :ok:, that's exactly the sort of anecdotal stuff I'm looking for. any other titbits where that came from?

Tinribs:
That's nothing to do with the Searchwater - it's the quality of nav input that affects the radar ground plot. Perhaps the IN in your Viscount just wasn't up to the job?

Croqu. Are the French replacing the RR Tynes', I would have thought they were the limiting factor on a refurbish/update of the Atlantique'.

AD'

AD, I don't know. Pontius, as you know it is time on task that counts. I seem to remember that the Nimrod needed a transit of 500nms to exceed the Shacks time on task, but the Atlantique would beat the Nimrod out to over 700nm, but my memory is not what it was. I was banned from speaking to VIPs in MAAU for expressing my views!

I would imagine the ability to act as a node in a fully networked and integrated ASuW/ASW force needs to be an absolute priority, so high speed and very secure data comms would be high on the list. If you see it, they need to see it, especially for things like land attack and over-the-horizon work.

Eliminating hosted aircrew would be my secondary consideration (boy I'm on thin ice now) - you have to feed them, provide ejection seats and scrabble boards, and they take up valuable fuel and equipment space. The technology isn't quite there yet particularly for rescue missions, but we are getting close. Autonomous functioning would be a must, because remote piloting links can always be interrupted.

It all depends if you're looking to design a lower risk platform using current technology, or if this is more of a forward look with the associated risks and costs of technology development. That needs to be one of the first questions defined by your project goals and deliverables.

For Fosini.....
 

......as long as you discount the S3-A (no longer in the asw game) there are no ejection seats in MPAs. No scrabble boards either and I did hear a dreadful rumour that even Uckers boards were no longer in crewrooms!!
When one hears phrases like "agile" "fully networked" "integrated" et alia, you know your in shakey ground territory.
I hold to my earlier post that THE most vital part of an MPA fit is a properly trained crew, working together,

The Ancient Mariner

Since this would be a new design, ejection seats could be a consideration.

Sorry to hear about the uckers boards though ;)

...ejection seat in the AEO position, controlled by the rest of the crew... ;)

Croquetter, only got described in the AEW Shack but remember spending a week or two getting as far as Benbecular but in a Nimrod entering the HUATA before a 180 into the North Sea (best trap ride we did) or doing one patrol in North Sea and a spec OP west of Ireland on the same sortie.

Don't know about the Atl but loved it doing 300+ in the Nignog running down a May. OTOH a Bear could out run a Nimrod.

Back to the OP, good - quiet jets, bad noisy props. Good - economical props - bad thirsty jets.

Provided a noisy prop could avoid running its sound footprint over the target it probably had the edge.

More grist for the mill, "hijacked" with acknowledgements to Arrse:

https://www.arrse.co.uk/community/th...y-lady.259150/ :ok:

Jack

Op,

Assuming the airframe gets you on task reasonably/relatively swiftly and keeps you there in relative/reasonable safety for a relative/reasonable length of time the deciding factor (by a country mile) is the internal mission fit, weapon load and, of course, competence of the crew.

All the airframes you mention, plus others, are perfectly fit for purpose, with of course individual pros and cons (some of which are mentioned, particularly by PN, whose points are pertinent and solid)

The mission fits and crews are/were/will be always the deciding factor as to which is superior. Thus a Nimrod MK1 was inferior to a P3C update 2 (albeit some US crews, especially the reserve ones did not have a fkn clue what to do with it :E), but the Nimrod MK2 quickly leapfrogged the P3Cu2, and so on and so forth.

I think the Neptune still holds the record for an airborne time at around 32 hours? Great if you can build it, but as ex Nimrod, I don't think we'd have been able to load enough honkers/pies to manage that sort of weight v. fuel airborne time.

I have a hazy recollection of the Atlantiques going home from SharpGuard because they couldn't carry the required payload for the requested duration at the high operating temps at the time. (Hazy recollection due to the room parties at the Baia Verde.)

Others have given you the Mission Tree as a system driver, I am going to invert that and give you the Cost Vee as an Inventory/Flight Hours restrictor. O&S costs are what make your platform useful, as much if not more than individual mission capabilities.

Looking at some common MPA mission element needs vs. Platform Costs:

1. ASST Hi/Lo 100 million entry 200hrs/year.
2. ASUW Hi/Lo 60 million entry 300hrs/year (the Sort to Morte cycle is critical in cluttered sealanes).
3. SAR 35 million entry 50hrs/year (depending on region, you can have so many live calls that training is only necessary for turnover reasons).
4. Overland ISR 50 million entry 500hrs/year (requires multiple service partnership agreements which means range time and coordination via big staffing).
5. ASW 150 million entry Variable. (Lotsa long range navigation training = pricey).
6. Signals 75 million entry. Variable (BO funded).

If you know your CPFH on a specific platform configuration, you can start to guesstimate your yearly O&S and that in turn sets your inventory size. Coverage is often more important than absolute capability in the civilian/peacetime missions while the exact opposite is true of warfighter capacity, both in terms of utilization rates and training hours.

The Kondor Mission. Sending an airliner sized platform into harms way to target naval traffic for weapons fired by other platforms is moronic because it doesn't provide the continuity of track to offset the asset value risk. The Tu-95 Bear D comes to mind as a platform which enabled the entire AVMF approach to sinking USN Carriers and REFORGER complexes but whose limited persistence and short sensor range as well as predictable track (you can spot the acoustics of the propjets with OTH-B and this plus the profile made it easy to kill) made it a simplistic target set, even discounting the Big Bulge limits. The Russians eventually resolved this with ROR/EOR and a variant of the Tu-143 drone which let them proceed directly to the mission area and gate through optical means rather than radar.

Conversely, using a large MPA in a littorals environment can be quite useful for the simple reason that a CN-235 or C-27 or even a Herk with RORO kit don't have the altitude/speed ability to roll back the sensor horizon while remaining well stood off from an air or coastal SAM threat but a turbine MPA can do either the low dash or the loitering look-in. Conversely, the threat naval small craft themselves often have very limited S2A capabilities and so, provided you are willing to accept limited operational area flexibility in terms of early acquisition and zone to zone patrol area switching a small turboprop can get you a long ways.

Moving from eyeball to shooter means scaling the platform and adding wing structural enhancement to support external pylon carriage as aerodynamic clearances. This tends to give some big hits in terms of operational radius (weight on end of wing is never a good idea as the necessary beefing carries through all the way to the roots). However; pylons are cheap compared to inserting a weapons bay. A compromise option which is being increasingly looked at is the CABS approach with a ramp system and an ejector system like MCALS. This tends to limit the ultimate size as penetration speed and standoff of your weapon (no Klub, no Brahmos) but it can be useful if you've already accepted the widebody hit for other mission reasons or because of existing inventory mods.

Search and Rescue is basically a coordination function for any platform in which it is not a primary mission driver. Simply because the Dumbo Driver on a deployed rescue craft and swimmers is a very high order risk for them and the platform. However; it has elements which can be combined with other systems/missions (AAR for helos and ASST capable ISAR for rapid traffic sort and look-in on high wave troughs). The big variable here tends to be how far out from how many dedicated basing points you want to cover. SAR can also have a big effect on airframe lifing if your chosen platform cannot get above the Wx.

Overland ISR. Though hardly new (it was done with Neptunes on the HCMT), one the more recent rediscoveries, via the Outlaw Hunter/Viking programs, was just how suitable the enhanced loiter of an ASW platform can be when employed overland to hunt for baddies in conditions where elevation and/or total search areas (or primitive/limited basing modes) conditions excluded the more conventional UAS option. Smaller platforms tend to be better overall (as small as a C-12/21) for economies reasons but a dedicated sensor operator cabin and multiple apertures favors the jet or larger turboprop for a higher threat areas, not least because you offset sortie costs with AAR. Where you are a heavy exponent of NSW in over the beach operations, an MPA can also be a comms relay, targeting and occasional a direct fires support platform of significance because it's got the service plug-in and range to integrate within the BMC2 command hierarchy directly.

ASW. Probably the least useful of the MPA roles, IMO. Anyone who has a fixation with Das Boot styled submarine warfare has no clue what the trends (see: Irans Type XXIII styled minis) are heading towards as unmanned assets and NCW enabled coastal defense by platforms that are either swarm kamikaze or pure sensor nodes for CAPTAM or landbased TELs. Even in those instances where you have an SSN/SSK operating inshore, the tendendcy is towards AShM, not Torpedo engagement, which means your threat zone has just doubled in size from a 10-15nm radial to 50nm (Western) and 100nm (Everyone Else). Hunting with airborne assets has few advantages compared to 1/10th cost coastal patrol surface alternatives due to flow noise issues and magnetics in the shallow water environment. Coverage + Cost counts and hulls beat airframes here, everytime.

Blue Water, the hull costs rapidly start to rise but ASW is even more of a sanitization mission (clearing the empty) set which has a long-dwell baseline requirement to catch the maneuver sprint. More than any other mission environment, this area really supports the use of dedicated UUV with fuel cells and a tender, backed by a long range torpedo delivery system off an otherwise undistinguished SSC. Active Search _works_ when it is off a rapidly relocatable, potentially sacrificial, signal source. Bistatics at sea have always been simple.

Strategic, the need is there as frankly there is nothing else which has the reactivity to get rapidlly to a threat boomer before it can unload the /other half/ of it's SLBM or SLCM load on you. But the problem becomes one of both initial and diminishing returns as well as the necessity of other-platform/system handoff to get preemptive engagement. This is really something that only the major powers can pretend to play at and since they are all nuclear capable with large attrition absorption factors, it's a game that is better not played. As we shift to SSLs for air defense and from subsonic to super and hypersonic flyouts (functionally replacing manned airpower which is both too slow and too costly for the daily DMPI counts achieved) this could change as you will increasingly see A2AD/ICD approaches denial simply outranged by platforms which are never vulnerable to BASM/ASCM as a carrier is.

The ulimate driver here then becomes the threat-mirror image extent to which an opfor appears to be willing to invest in the cripplingly expensive technology base of submarine design but with the lapsing of many technology proliferation regimes, there is a definite cost trend towards mixing strategic and theater platforms as hull counts, using the SSGN-728 example off Libya as test point (imagine this with an HSSW with 1,000nm range or a CICMB with 1,500nm range and you begin to understand the differentiation between Blue Water and Strategic sets, at a sub nuclear level...).

Signals used to be a cheap and easy way to avoid the Pueblo/Liberty scenario by throwing a palletized broadband receiver into the back of whatever with a plug'n'play hatch or drogue line for the aperture. Increasingly, this is simply not the case as many threat states simply show no intention of respecting National Asset status or 12 mile limits and either ram or shoot down our E-ferrets. If you're not stealthy, cool and able to persist at over 60,000ft, you're not survivable and that's in peacetime.

This as well as the extended dwell condition (closed societies, different ethnies = impenetrable) prediction on many test events is driving us towards highly specialist platform capabilities in the higher end theater platforms and towards sub-maritime systems as the ESM packages continue to scale down in roles like the ISA Centra Spike activity and I'm sure, later ones chasing cell phone comms in SWA (if nothing else, the need to move to low level to get good directional capture on these systems, depending on the tower node geometry takes the big platform out of the picture).

So... Your biggest 'industrial secret' (must be kept from defense industry bidders at all costs) is the program allocation you have worked out within your Defense Acquisition agency in civiian government as being politically sustainable. You then take HALF that value to your spec writers in the developmental side of the game (one of the unmentionables of acquisition is that there are more leaks from inside defense than the political side, simply because of incestuous contacts between serving/retired uniform staff and the much higher career penalties for a politician and his small cleared-in staff) and make it fund your primary mission driver as platform selector, modified by any requirement/option to use existing inventory.

Once you have set your principle platform size, you add more nice-to-have secondary missions to the limit of your unstated program allocation and begin to do trades studies with other systems in an NCW condition. The Primary Mission set must make it through the neck of the vee as a funnel. Anything past that is gravy but there are options to losing so many missions that your program becomes to specialized to be funded.

Having it be a center enabler node in a star of UUV/USV/UAS that can be ported to the theater separately by another service is going to become an increasingly important MPA conditional qualifier as environmental conditions, especially those specific to a warighter, simply makes the air-only solution untenable for capability or cost. That said, BMC3 as coordination will take on increasing importance as we will increasingly find ourselves no longer able to support the costs of service centric, capital-center enabled, high intensity, warfighters. In this, a 500 million dollar MPA vs. a 25 billion dollar CVSF tends to set perspective.

But to scale wider requires a joint/multiservice command structure which has _serious acquisition authority_, to reconfigure operational commands into co-supporting architectures, separate from any uniform color loyalties. To functionally effect this means tearing down the military and rebuilding it and is one of the big reasons why RMA is the promise which institutional-inertia simply doesn't happen short of mass die off from total funding starvation.