Martin P6M Seamaster

[Jane-DoH]

From what I remember reading, this aircraft had afterburners. Being that (as far as I know) it was subsonic -- why did it need those?

[hval]

Jane-Doh,

Sea planes always fascinated me as a child. The Seamaster was intended to deliver nuclear store. Polaris systems were used instead.

You are correct; the Seamaster did indeed have afterburners. They were intended to provide additional power on take off. Unfortunately a slight fault in the design was found; the engine nacelle design was such that when in afterburner mode had a tendency to burn the rear fuselage and induce sonic fatigue.

The two afterburning jet engines were located side by side in each of' two nacelles mounted on top of the wing immediately adjacent to either side of' the fuselage. (The afterburners, an unusual feature for a large subsonic aircraft, were for use oil takeoff.) Inlets swept back at nearly the same angle as the wing leading edge were found to be unsatisfactory and unswept inlets were finally adopted; exhaust nozzles were behind the trailing edge of the wing.The location of' the engines was, of course, strongly influenced by the necessity of minimizing spray ingestion during operation on the water.

I copied that last paragraph from P6M SeaMaster (http://www.globalsecurity.org/military/systems/aircraft/p6m.htm). Go have a read

[zetec2]

Just a thought, maybe to help it unstick from the water when fully loaded ? was a big machine , Paul H.

[Kitbag]

Although not supersonic it was required to achieve M0.9 at low level, this, combined with a max t/o weight of about 160000lbs may go some way to explaining it. The nature of a flying boats landing medium does result in a built in headwind.
Turbojets were still pretty gutless in the early '50's - the original design was going to use turbo-ramjets, but after development issues these were replaced by afterburning Allison j71s in the prototype and pre production aircraft. As far as I know, the production series had non afterburning J75s that were rated at about 17000lbs. This (http://www.globalsecurity.org/military/systems/aircraft/p6m.htm) seems to be the most authoritative detail on the web.

[jamesdevice]

these explain a fair bit re the engines http://www.youtube.com/watch?v=QowTqmxYZ1Q&feature=related Martin YP6M SeaMaster - YouTube http://www.youtube.com/watch?v=mqhhs5xrGek Shame we don't have fleet of these.

[Jane-DoH]

hval

Sea planes always fascinated me as a child.

I found them fascinating too, though I'm not sure for the same reason: For an airliner they could be so much bigger as a 10,000 foot takeoff run wouldn't be a concern, and night-vision could allow you to gauge the height of the swells, which would even make nighttime operation safe.

The Seamaster was intended to deliver nuclear store. Polaris systems were used instead.

Correct, it could also deliver conventional ordinance including bombs, and even mines.

They were intended to provide additional power on take off.

That would give the plane a pretty good T/W ratio -- I'm surprised you'd need such a high T/W ratio to get a sea-plane out of the water.


Kitbag

Although not supersonic it was required to achieve M0.9 at low level, this, combined with a max t/o weight of about 160000lbs may go some way to explaining it.

It needed burner to hold subsonic speed at sea-level? I thought it would be able to fly dry down-low....

Regardless, just the fact that it weighed less than a B47, could carry a greater load at a higher speed up high and down-low, was sturdier (I don't know what it's maximum g-load was, but that aircraft was built like a tank), had a greater thrust to weight ratio and a lighter wing-loading all sound like awesome advantages, though truthfully I don't know if it could fly as far.

Turbojets were still pretty gutless in the early '50's - the original design was going to use turbo-ramjets

Why would they need turbo-ramjets? How fast were they originally planning to design this aircraft to fly? Are you confusing this design with a Mach 4 design Convair proposed -- a turbo-ramjet makes more sense for that design than a high subsonic aircraft...

As far as I know, the production series had non afterburning J75s that were rated at about 17000lbs.

Considering the thrust figures of jet-engines almost always seems to be under-rated (either a fudge-factor is incorporated, or the thrust figures are based on conditions other than sea-level thrust) -- as I understand it J75's had thrust levels as low as 15,800 (as used on the B707-220), with most around 18,000 - 22,000 lbf dry (this is consistent with the statements that the J75 was 50% more powerful than the J57).


jamesdevice

Shame we don't have fleet of these.

Seaplane aircraft have a fundamental advantage in the fact that more of the Earth's surface area is covered by water than by land. The only thing that could be better would be an amphibious aircraft.

The only drawback that the P6M had would be that it wasn't really designed to reliably land at night as the height of the swells could not be reliably gauged. Though as far as I know the plane could refuel in mid-air, so as long as there wasn't an imminent problem, they could just keep refuelling until the sun comes up, then land.

[dagenham]

It was supersonic in a dive

It also had aerodynamic weaknesses - the first prototype had a tailplane problem which lead to both wings clapping hands and all where lost in the following crash

What killed it after a fair few were built , but not put in to service, was not only polaris but the supercarrier ( nimitz class ?) programme and the fact the bomb bay doors sealong system was not massively reliable.

Cool programme none the less

[GreenKnight121]

Wrong decade, dagenham.

Martin P6M Seamaster:
First flight 14 July 1955; program canceled August 1959.

the Supercarrier program:
CVA-59 Forrestal: Commissioned: 1 October 1955
CVA-60 Saratoga: Commissioned: 14 April 1956
CVA-61 Ranger: Commissioned: 10 August 1957
CVA-62 Independence: Commissioned: 10 January 1959
CVA-63 Kitty Hawk: Laid down: 27 December 1956, Commissioned: 29 April 1961
CVA-64 Constellation: Laid down: 14 September 1957, Commissioned: 27 October 1961
CVA(N)-65 Enterprise: Laid down: 4 February 1958, Commissioned: 25 November 1961
CVA-66 America: Ordered: 25 November 1960
CVA-67 Kennedy: Ordered: 30 April 1964

Note:
CVAN-68 Nimitz; Ordered: 31 March 1967
etc.

Note2: the "A" (attack) part of the supercarrier designation was dropped 30 June 1975.

[hval]

Jane-Doh,

Seaplanes may be split into two groups; float planes and flying boats. Neither is able to take of in particularly rough weather, in fact the weather needs to be relatively calm. Flying boats are able to take off in rougher weather than sea planes. Sea state/ water state limits the number of days that sea planes may take off; more so than an aircraft taking off from a runway on land.

Floating objects are another hazard

A seaplane during take off has to overcome hydrodynamic forces (water drag is the major part of the forces resisting acceleration). This resistance reaches its peak at a speed of about 27 knots, and just before the floats or hull are placed into a planing attitude. Several factors greatly increase the water drag or resistance; heavy loading of the aircraft or glassy water conditions in which no air bubbles slide under the floats or hull, as they do during a choppy water condition. In extreme cases, the drag may exceed the available thrust and prevent the seaplanes from becoming airborne. This is particularly true when operating in areas with high density altitudes (high elevations/high temperatures) where the engine cannot develop full rated power

For seaplanes, the forces involved in take off are different to land planes. Sea planes have to overcome hydrodynamic forces which require additional power (I think of the water as being “sticky”). These forces increase until the float hull is out of the water or on the stepping plane. Did you know that float planes have two hull designs? One for when the aircraft is sitting in the water/ taxying around and one for when on the stepping plane and taking off.

I am now going to quote from a useful website (Flying Seaplanes (http://www.pilotfriend.com/training/flight_training/seaplanes/takeoff.htm)): -

The seaplane takeoff may be divided into four distinct phases:
(1) The "displacement" phase (plane sitting there or taxying)
(2) the "hump" or "ploughing" phase, (accelerating for take off)
(3) the "planing" or "on the step" phase, (overcome most hydrodynamic forces, accelerating for take off)
and
(4) the "lift off." This is where the wings produce lift and start to raise the hull from the water.


Take a look at the web site I have linked to. It may answer many of your questions re sea planes.

Sea planes are great, but economically, as passenger aircraft, they were not viable in todays requirements for being on time. As stated above, not only do sea planes have to take in to account the same weather conditions as land planes, but also the added component of sea state.

Hval.

[Shaft109]

Is it me or does this aircraft (or sea plane?) have more than a passing ressembance to a HP Victor?

Just the overall layout but especially the tail section.

[jamesdevice]

tail flutter test Flutter Test of Y-P6M t-Tail - YouTube

[Jig Peter]

"Victor-like" the Seamaster's tail certainly is, but I am also reminded of the Soviet Union's equivalent, by Myasishev (sp?) whose Soviet and NATO designations escape me*

Or was it Beriev? Aged grey cells oscillating ...
Over to the experts with more than memories to rely on ...

[jamesdevice]

MYASISCHEV MYA-4 "Bison" http://www.youtube.com/watch?v=DGrCqbuftSY

[BEagle]

Jig Peter, the aircraft to which you refer was not the Myasishchev M4 "Bison", it was the Beriev Be-10 “Mallow”:

http://i14.photobucket.com/albums/a341/nw969/Mallow.jpg

[jamesdevice]

I assumed the meant the Soviets equivalent to the Victor - which was arguably the Bison However theres a striking similarity to all three - especially the Bison wing profile

[Jig Peter]

Thanks Beagle (fount of much knowledge) for the photo - wasn't there also a 4-engined one with engines above the wing, like the Seamaster?
Lurking in my erratic memory is the thought that some were based in the Russian Far East, and also seem to appear in shots of "water bombing" operations.
Regards and respect,
JP

[jamesdevice]

theres two you could be thinking of, both by Beriev. Both are much more recent though
Be-200 https://secure.wikimedia.org/wikipedia/en/wiki/Beriev_Be-200
A-40 https://secure.wikimedia.org/wikipedia/en/wiki/Beriev_A-40
A-40 might make a good Nimrod replacement... More...Beriev A-40 - YouTube

[dagenham]

re carriers etc - same funding discussion re what USAF, USN and USMC have from a deterent perspective.

the original great planes documentary, not the trashy discover remake gives a good overview of the projects going on publically and not publically and how the infighting panned out.

the seamaster was cancelled really before it flew....... really keeping martin in business

really interesting to compare the US approach with that of UK

see wiki " The major defense budget cuts of the Eisenhower administration were forcing the Navy to make choices. In August 1959 Martin was told to halt operations; the program was going to be canceled. Seaplanes were a small community in Naval Aviation, and the P6M, significantly over budget and behind schedule, was competing with aircraft carriers for funding. The Navy had an impending superior system for the nuclear strike role, the Fleet Ballistic Missile Submarine." ref Martin P6M SeaMaster - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Martin_P6M_SeaMaster)

[jamesdevice]

how much practical use would it have been in a non-nuclear role? e.g. as a maritime patrol aircraft? Or as a tactical bomber? Strangely enough as I type this I've got a you-tube video running about "the nuclear bomber" and it states that the USN actually intended powering the turbines with a nuclear reactor.

[Jane-DoH]

dagenham

It was supersonic in a dive

Oh, I didn't know that

It also had aerodynamic weaknesses - the first prototype had a tailplane problem which lead to both wings clapping hands and all where lost in the following crash

I thought that was a deep-stall related issue (happens to T-tailed planes). The airframe was subjected to 9g's.

What killed it after a fair few were built , but not put in to service, was not only polaris but the supercarrier ( nimitz class ?) programme

The first super-carriers were the USS Forrestal. Part of me honestly thinks it would have been interesting to see fleet-carriers that were more like the Midway size but with elevators, arrestor cables, and catapults to operate heavier aircraft (albeit a lower number). Sounds counter-intuitive but even if each carrier had a little bit less fighter capacity; if you had a significantly greater number of carriers, you would technically have more carrier-based fighters and attack-planes in total.

If you had a large number of carriers and one goes to the bottom, you lose a smaller percentage of your overall carrier strike force; if you have a few super-carriers, a loss is far more catastrophic; furthermore it will take longer to replace it.

and the fact the bomb bay doors sealong system was not massively reliable.

I'm surprised they couldn't fix it as Martin had built seaplanes before.


hval

Seaplanes may be split into two groups; float planes and flying boats. Neither is able to take of in particularly rough weather, in fact the weather needs to be relatively calm. Flying boats are able to take off in rougher weather than sea planes. Sea state/ water state limits the number of days that sea planes may take off; more so than an aircraft taking off from a runway on land.

The P6M was a flying-boat technically right?

[Jane-DoH]

jamesdevice

how much practical use would it have been in a non-nuclear role? e.g. as a maritime patrol aircraft? Or as a tactical bomber?

It was designed to carry both conventional and non-nuclear armament. In a maritime-patrol aircraft, I'm not sure how it would fair from the endurance standpoint as it was turbojet powered (even the Nimrods were powered by turbofans).

As a tactical-bomber, there's nothing that says you can't use a strategic bomber to bomb military targets. It could fly fast at low altitude for a large aircraft, it was said to have good handling characteristics, and it was a sturdy aircraft (the incident that resulted in a structural failure resulted in a g-load of 9g or more) probably capable of pulling at least 6g.

Strangely enough as I type this I've got a you-tube video running about "the nuclear bomber" and it states that the USN actually intended powering the turbines with a nuclear reactor.

I have seen some concept drawings of this...

[jamesdevice]

did you just bump the thread by deleting the post and then reposting it?

Reason I asked the question about non-nuclear use was whether it would be any use in the current Libyan problem. Offers a third solution in the land vs carrier dispute. Or would potential sea-state problems be too much of an issue?

[Harley Quinn]

Good question about the efficacy of the Martin aircraft in Libya today:rolleyes:. Oddly enough I don't think even the RAF would still be using a 55 year old design in front line service though, and don't pull the B52 thing, the current frames are only 50.

[jamesdevice]

OK, be sarcastic if you want, but what if you had a modernised equivalent? Its the concept I'm getting at. And who knows - if it had gone into service, it may have had a production run as long as the B52. I wonder what the Seamaster development equivalent to the B-52H would have been

[Willard Whyte]

a production run as long as the B52

What, 10 years?

[jamesdevice]

yep. And the remaining 'H models are scheduled to last until 2045
Supposedly.... If it happens it'll make the surviving ones 82 years old at retirement
The oil's going to run out first

[John Farley]

The oil's going to run out first

I thought they were already flying some on fruit and veg

[Willard Whyte]

yep. And the remaining 'H models are scheduled to last until 2045
Supposedly.... If it happens it'll make the surviving ones 82 years old at retirement
The oil's going to run out first


OK, I'm not having a dig to have a dig, but... The longevity of BUFF is quite remarkable, but it had a relatively short production run, which is to what you originally referred.

[jamesdevice]

OK, so I'll re-ask my question in a way thats less open to misunderstanding,
Could a modern sea-plane bomber provide a useful alternative to land or carrier based aircraft in a conflict such as that currently in Libya?
Could you safely base it with and replenish it at sea from your surface fleet?

[gasax]

In essence not really!

The fleet would have to have access to sheltered water - sheltered not just from the weather but also from 'bad people and things'.

Seaplanes have landed offshore - and some of them have actually taxied or beeen towed home - but the sea state needs to be very reasonable - so this adds a massive constraint.

Seaplanes made a lot of sense when building long runways was difficult or expensive, now that is comparatively easy with the mechanised equpment we have. The constraints in terms of payload, operations (weather, maintenance, support etc) simply make it all too hard to be worthwhile

[LowObservable]

The SeaMaster was a fascinating machine. Ask even a well informed online forum to name two 1950s nuclear bombers designed for low-level operations and the answer will be "Valiant B.2 and .... errrmmm?".

There's quite a lot out there about the tech, but not so much on operational plans. What were they going to do, lurk in a fjord in Iceland and mine the :mad: out of Murmansk?

[jamesdevice]

the fact they contemplated powering it with a nuclear reactor makes it even more intriguing. Just how long could you keep it aloft before crew fatigue issues kick in? It doesn't look big enough to carry any relief crew.
or maybe the reactor was simply to avoid lengthy at-sea refueling: replenishment at see would just mean reloading the bomb bay (did you notice this was done from ABOVE via the rotating carousel?) and exchanging crew

[LowObservable]

JD - The nuclear-powered concept was a different and much larger aircraft.

Also, for V-bomber fans - the definitive SeaMaster history...

Amazon.com: Martin P6M SeaMaster (9780970066206): Stan Piet, Al Raithel: Books (mine is on the bookshelf next to the Rottweiler's food bowl)

... doesn't talk about turboramjets at all. The original planned engine was the Wright J67, an Americanized Olympus.

[Jane-DoH]

jamesdevice

Offers a third solution in the land vs carrier dispute.

Well, in truth if a sea-plane strike force really took off, carriers would have gotten the short-end of the stick.

Or would potential sea-state problems be too much of an issue?

I suppose it depended on where you'd attempt to land, but modern day with night-vision technology such an aircraft could takeoff and land at night without trouble.


Harley Quinn

Oddly enough I don't think even the RAF would still be using a 55 year old design in front line service though, and don't pull the B52 thing, the current frames are only 50.

Irrelevant, for the following reasons

1.) The P6M was actually a newer design than the B-52

The XB-52 first flew in 1952; the XP6M first flew in 1955
The YB-52 first flew in 1954; the YP6M first flew in 1958
The B-52A first flew in 1955; the P6M-1 was to enter service in 1959 or 1960.


2.) If the P6M entered service, it's likely there would have been several variants of the P6M built of which the newest ones hypothetically could have remained in service until present.


Willard Whyte

What, 10 years?

I think he meant the total number of years in service...


John Farley

I thought they were already flying some on fruit and veg

Are you talking about something like biodiesel, or are you talking about ethanol, or something else?

I don't think it's a good idea to make fuel from fruit and vegetables because it will drive up the price of food; as for biodiesel, you don't need fruit and vegetables to do that; you can make biodiesel from deep-fryer oil, methanol and lye.


gasax

The fleet would have to have access to sheltered water - sheltered not just from the weather but also from 'bad people and things'.

For Libya, you could operate out of the Mediterranean, use aerial refueling as necessary; then attack Libya with cruise-missiles, or overfly Libya and use precision guided bombs. At low-altitude it could fly at Mach 0.9, and behaves better than a B-52.

Still, there are numerous land-bases in the mediterranean that could be used for the same purpose and I think a B-1, an A-10, or an F-18 would be better suited for the task.


LowObservable

There's quite a lot out there about the tech, but not so much on operational plans. What were they going to do, lurk in a fjord in Iceland and mine the :mad: out of Murmansk?

Actually, in those days that seems like it might have been a good idea :}

The nuclear-powered concept was a different and much larger aircraft.

Okay, that makes sense. How much larger anyway?

... doesn't talk about turboramjets at all.

I'm guessing the statement about turbo-ramjets or J58's was either misinformation, or was information that pertained to a proposed Mach 4 seaplane which Convair did some work on.

The original planned engine was the Wright J67, an Americanized Olympus.

Well, as I understand it, it was a more powerful variant of the Bristol Olympus's that were then in service. Eventually more powerful variants were developed obviously.

[GreenKnight121]

Jane-DoH & John Farley

Quote:
I thought they were already flying some on fruit and veg
Are you talking about something like biodiesel, or are you talking about ethanol, or something else?

I don't think it's a good idea to make fuel from fruit and vegetables because it will drive up the price of food; as for biodiesel, you don't need fruit and vegetables to do that; you can make biodiesel from deep-fryer oil, methanol and lye.

Actually, the B-52 flew on (and is now certified to use) a Fischer-Tropsch fuel derived from natural gas.

It was a USN F/A-18E that flew on a 50/50 blend of conventional jet fuel and a biofuel that comes from camelina, a hardy U.S.-grown plant that can thrive even in difficult soil.

However, various private and commercial jets have flown on various bio-fuel/jet fuel mixes.

[LowObservable]

Fischer-Tropsch

An excellent name for a cocktail, since after three you couldn't pronounce it without getting 86ed for spitting on the bartender.

Piet and Raithel say that the whole Seaplane Striking Force concept - which included the SeaMaster, the F2Y Sea Dart for air defense and the R3Y Tradewind for logistics - started after the Truman administration canceled the USS United States, the first supercarrier. The Navy was worried (as was the Army) that they would suddenly become irrelevant if all war was to be nuclear.

The P6M's primary role was minelaying but it was also tested with nuclear bomb shapes. It was a difficult and (for the 1950s) long development program - the P6M-1 was far from operationally suitable and the P6M-2 was different in many ways and only just emerging from development when the project was shopped.

It's near the top of the "damn, why did the bu99ers have to scrap all of them?" list.

[Jane-DoH]

GreenKnight121

Actually, the B-52 flew on (and is now certified to use) a Fischer-Tropsch fuel derived from natural gas.

That makes more sense.

It was a USN F/A-18E that flew on a 50/50 blend of conventional jet fuel and a biofuel that comes from camelina, a hardy U.S.-grown plant that can thrive even in difficult soil.

Okay, that sounds better than using corn.


LowObservable

Piet and Raithel say that the whole Seaplane Striking Force concept - which included the SeaMaster, the F2Y Sea Dart for air defense and the R3Y Tradewind for logistics - started after the Truman administration canceled the USS United States, the first supercarrier. The Navy was worried (as was the Army) that they would suddenly become irrelevant if all war was to be nuclear.

The supercarrier was the preferred choice because at the time the US Air Force was not just trying to achieve a nuclear monopoly -- but they were trying to sink the Navy. They were effectively arguing that the Air Force and Army could do everything that the US Navy could (and in fact, during parts of WW2, the USAAF was doing a better job at laying mines from the air, than the Navy was from the sea). The Air Force roundly disliked carriers because it was one aerial asset that they could not fully control.

While the USN could have developed a flying-boat nuclear-bomber at the time, which would have been better from a practical standpoint it wasn't the best choice from a political standpoint as the USAAF/USAF could argue that they could operate sea-planes too. The carriers however were, an asset the USAF couldn't control, USAAF/USAF pilots were not trained to operate off carrier decks -- and for this reason, the USN wanted a carrier-based nuclear-bomber which of course necessitated a new carrier to be built to operate them.

Even though the USS United States was cancelled, the motions the Navy went to, simply to build the bomber and carrier effectively gave the USN the justification to basically exist. Once that was done, the Navy could now focus on other options (more practical ones too) which included the Seaplane Strike Force.

The P6M's primary role was minelaying but it was also tested with nuclear bomb shapes. It was a difficult and (for the 1950s) long development program - the P6M-1 was far from operationally suitable and the P6M-2 was different in many ways and only just emerging from development when the project was shopped.

Yup, which kind of makes it similar to the TSR-2 (though admittedly, not quite as cool) -- a great design that could have worked but politics doomed it.

It's near the top of the "damn, why did the bu99ers have to scrap all of them?" list.

In a way, had this seaplane strike force worked, it's possible that carrier-aviation could have been hurt or killed.