Merlin powered carrier fighter other than Seafire

[Piper106]

Looking fo suggestions on another Merlin (or Allison) powered single seat carrier fighter with performance comparable to land based fighters.

Rules for this discussion.
H*ll has frozen over and the American Navy is willing to consider a liquid cooled engine on a carrier, so do not limit to British designs.
We need not limit ourselves to designs that can operate from short slow escort carriers. Assume fleet carriers with decent wind over a long deck.
I DON'T WANT THIS TO BE A THREAD DISCUSSING THE SEAFIRE I am looking for a liquid cooled carrier fighter that is not a Seafire.

Should we navalize the P-40?? A single seat Defiant with fixed wing guns and without the turret?? Is there a 'easy' fix that would make the Mustang suitable for carrier use by average avaitors?? Was there a 'paper airplane' on the drawing board???

I will start. The American Navy tested a P-51D Mustang with an arrestor hook. They found that reasonable landing speed for that version was too close the limits on wartime arresting gear. It would have been too much of a handful for average pilots. My suggestion would have been to navalize the Allison powered Mustang I / P-51A. These early Mustangs were over a thousand pounds lighter than the Merlin Mustangs and therefore having a slower stall and landing speed than the Merlin Mustangs. Wide track landing gear, and oh... up to an altitude of 20000 feet faster than that Merlin engined carrier fighter that we will not talk about.

 

[Kryten]

That will be the Sea Hurricane then!

How about a Merlin engine P39, tricycle landing gear must be an advantage on a carrier?

 

[tomo pauk]

Several aircraft:
-P-40; the P-40F might be the best
-P-39 (not the lousy Airabonita) - the smallish fuel tankage willt hamper the combat radius endurance; issues with CoG once front guns have used up the ammo
-P-51 (with somewhat bigger wing, so wing loading is lower; maybe add the slats)
-single seat Defiant - put the fuel in fuselge, so guns can be installed in wings

 

[RCAFson]

The USN actually called for Merlin engined fighters for both shore and carrier operations:

...Another aspect of
the attack that proved inadequate was fighter escort. To Fletcher the folding wing F4F-4s
represented no improvement over the fixed-wing F4F-3s, except more F4F-4s could be
carried. He echoed the call of Halsey and others of the urgent necessity'' for detachable fuel
tanks to increase their effective attack radius beyond 175 miles. Spruance and Browning
rated the Grumman Wildcat "greatly inferior'' in comparison with the nimble Japanese
Zero. On 20 June Nimitz relayed their fears to King, noting the "extreme and apparently
increased superiority performance of 0 fighters'' was mitigated only by the vulnerability
of Japanese planes and the superior tactics of the U.S. Navy fighter pilots. "Overall results
have been bad and will be serious and potentially decisive with improvement that must
be expected in enemy tactics.'' Remarkably he called for army Curtiss P-4OF Warhawk
fighters to replace navy F4F Wildcats and Brewster F2A Buffaloes in all marine fighting
squadrons defending forward bases and even asked that the P-4OF "or comparable type"
be tested for carrier suitability; In the meantime the F4F-4s must be lightened, and their
ammunition supply increased even should that require reverting to four guns in place ofsix.
The swift introduction ofthe Vought F4U-1 Corsair fighter was an"absolute priority.'' Thus
after Midway the top fleet commanders experienced a serious crisis of confidence over the
effectiveness of the basic U.S. carrier fighter, a worry that would soon influence Fletcher's
most controversial command decision...
Black Shoe carrier Admiral, p.200

I suspect that the USN might have welcomed the Sea Hurricane in 1942.

 

[Piper106]

Sea Hurricane.
On the plus side, light wing load and good deck handling. Eight .303 machine guns would likely shred Japanese aircraft as well four or six .50 caliber guns. If there are Fw200 Condors and the like about, we can go for the 20mm cannon armed versions of the Hurricane. Negatives... slower than a P-40, slightly less fuel capacity / no advantage in range compared to P-40. The biggest black mark is that by early 1942 performance is falling behind that enemy land based fighters.

P-39
I have frequently been in favor of the P-39 / P-63. In previous discussions on this board, I have advocated limiting the P-39 to just the nose armament, which frees up space in the former wing gun bays for additional internal fuel. But would the US Navy be ready for a liquid cooled engine AND tricycle landing gear?? I admit that the starting premise was the US Navy would look at a liquid cooled engine but even with h*ll frozen over this might be too much to bite off in one sitting.

Navalized P-40
Maybe tthe easiest sell.

P-51.
Even the Allison engine versions had far better performance than the P-40 in both speed and range. Could the landing characteristics be made satisfactory for carrier operations by average pilots?? Would leading edge slats as suggested by Tomo Pauk make a significant difference in low speed handling??? Could changes in the flaps help low speed lift?? How much might extension of the wing span help, and at how much loss in performance???

 

[Shortround6]

Sea Hurricane?

Needs a wing fold for the US. Needs more fuel.

P-39 needs?

A new Airplane? The Airabonita used tail dragger gear and a bigger wing and light armament (cowl guns were .30 cal) which in fact was never installed and still failed carrier qualification at 6742lbs gross and 5352lbs empty. Service P-39s went around 6200-6300lbs Basic (empty equipped= guns,armor, radios, etc but NO fuel,oil,ammo) figure 7300-7400lbs for clean without wing guns (?). And that is with 120 gals fuel.

P-40?

see Zeno's or Flight manuals. P-40E needed 1050ft of runway at 7500lbs 0 wind. The Army fighters need a more runway than the navy fighters. In some cases a LOT more. The fact that Army fighters were flown off carrier decks in ferry operations (with less than full fuel tanks and little or no ammo, in fact in some cases with some guns removed) does NOT mean they are suitable for day in/day out carrier operations with just a few minor "tweaks". For Navy use they NEED full guns and ammo, full tanks if not drop tanks.

AN F6F can take-off in less distance carrying a drop tank and a 1000lb bomb than a P-39 can clean.

Allison(or Merlin single stage Mustang)?

When does it show up and what gets delayed because you are basically sticking a new wing on it? leading edge slats, new flaps, extended wing tips (which still have to meet the "G" load requirement). And according to one chart ( and it could be in error?) an Allison powered P-51A (clean) needs around 340 feet more runway than a P-40E (Clean). P-51Ds needed less runway even when heavier because they had more power.

Admiral Fletcher could request or suggest anything he wanted. He was not an aviator and may not have had a good understanding of what made good carrier planes, He knew what he had wasn't working (lacking performance) and was looking for a quick solution. There wasn't one.

 

[nuuumannn]

In 1938 the British Air Staff released N.5/38 and N.6/38, which called for a carrier based two-seat fighter and a turret fighter respectively. These were updated to N.8/39 and N.9/39. The preferred aircraft to N.8/39 was the Supermarine 333, which was based loosely on the Spitfire, but stretched as a two-seater; one was powered by a Merlin, the other by a Griffon, but aircraft to these two specs were not built. The Type 333 had a cranked wing that abandoned the elliptical form and was tapered on both leading and trailing edges. Armed with four 20 mm cannon in the wings, the Merlin engined version was to be able to reach 34,700 ft with a sea level rate of climb of 2,650 ft/min. Top speed stipulated in the requirement was to be over 275 kts at 15,000 ft.

A single-seat Defiant was investigated by BP - the P.94, which was intended as a stop-gap in case Spitfire or Hurricane production failed to meet expectations during the Battle of Britain. The prototype K8310 had its turret removed for aerodynamics trials. The Defiant was certainly hardy enough and its undercarriage, once the issues were sorted out was strong enough for carrier operations and indeed BP entered a design to the afforementioned N.9/39. On paper the P.94's performance would have been better than the Hurricane's, so it's likely to assume it might have been the same in a naval variant. The issue with the Defiant however was its speed; it was very slow, but I suspect that much to the local strengthening around the centre fuselage to incorporate the turret would not have been present in a single seater, thus saving structural weight. A carrier variant would certainly be feasible in the early years of the war.

By the time the war broke out however the Royal Navy was already investigating a Griffon engined two-seater - the Firefly and further single-seat fighter projects launched were to have more powerful engines than the Merlin, nominally the Griffon, Sabre or Centaurus. Further naval fighters such as the Firebrand and indeed Boulton Paul's own naval fighter designs were powered by these engines.

 

[Piper106]

P-40E needed 1050ft of runway at 7500lbs 0 wind. The Army fighters need a more runway than the navy fighters. In some cases a LOT more.

Hum... and the 0 wind take-off distance applies... how?? A carrier by its own motion makes 25 mph wind over the deck when the air is still. And if there is any wind, the intent (admittedly not always possible) is the steam into the wind, so on an average day there would be... what... 35 mph wind over the deck??? What does that do to the takeoff distance???

Oh by the way... A F6F @ 12600 pounds has a higher wing load (lbs per square foot) than a P-40 at 7500 pounds weight. I don't recall the F6F having any super duper high lift devices to make up for the higher wing load.

 

[Shortround6]

Take-off distance matters because the Navy planes under the SAME conditions have take-off distances of 620ft (F2A-3) to 950ft (F6F-3 at 12213lbs) with the F4Fs (various) and F4Us (various) F6F-5 falling in between. It is not a question of getting them off the deck at all, it is a question of launching from a deck park that takes up 1/3 to 1/2 the flight deck.

Granted they are dive bombers but......

Adding 25-35 kts of headwind will shorten up the distance for ALL planes but it will not reverse the ranking position in a list of aircraft from shortest to longest take off runs.

And "Oh by the way" the F6F has a slightly better power to weight ratio for better acceleration to flying speed and not all airfoils generate the exact same amount of lift per sq ft.

If you don't like those reasons take it up with people that wrote the manuals.

See: http://zenoswarbirdvideos.com/Images/P-40/P-40TOCLC.pdf

And please note that this chart is for 0 degrees centigrade, warmer air will increase take-off distance.

Chart for F6F temp not given: http://zenoswarbirdvideos.com/Images/F6F/F6FTODIS.pdf

 

[Piper106]

Sorry about that Shortround6. Didn't mean to be snotty, but I now see that that I added a big scoop of snotty to my earlier reply. Again, sorry.

Yep, the charts don't lie, The P-40E is about the the best Army fighter in terms of shortest take-off distance, and slowest landing speed, and even then it is not in the same league as the Navy airplanes in either regard. On the other hand, based on what I have read recently, the split flaps used by the Army P-40s would be mainly just more drag for landing. Does not seem like split flaps are the best choice for improving lift at low speed for either take-off or landing.

The P-39 is a real dog with quite a long take-off run, but (in hindsight) not surprising considering the small wing area.

 

[stona]

And no one is considering the inherent design problems of landing these aircraft, designed for airfield operation on a carrier. They are not easy things to overcome without major alterations, if at all.

Most land based aircraft of the period were designed to land with a maximum rate of descent between 6 and 8 feet per second. US carrier based aircraft were designed to land with a rate of descent of 12 feet per second without breaking. This was a big problem for converted aircraft like the Seafire (7 fps maximum).

What about landing speeds? To land on a carrier the Seafire had to make a final approach at only 1.05 Vse, the Sea Hurricane only slightly better. US carrier aircraft were designed to approach at 1.2 Vse giving a much better margin above the stall.

Many other aerodynamic factors need to be considered. For example good acceleration and poor decceleration (slipperiness if you like) are desirable attributes for a fighter aircraft, but don't make it easy to catch wires on an aircraft carrier.

P-40s were flown off carriers (just like Spitfires and Hurricanes) but they couldn't land back on.

Converting aircraft originally designed for operation from airfields to operate from carriers is never an easy thing to do. The best carrier aircraft were designed as such.

Cheers

Steve

 

[Shortround6]

Sorry about that Shortround6. Didn't mean to be snotty, but I now see that that I added a big scoop of snotty to my earlier reply. Again, sorry.

Apology accepted.

Some diagrams of flaps and high lift devices can be found here: http://www.ww2aircraft.net/forum/av...rier-based-aircraft-worth-effort-39409-4.html

Post #50.

Please note however that the improvement in lift given is IF the entire wing has the specified flap or slot/slat. Partial span flaps/sots/slats only improve the area of the wing they cover. Also please note the the 3rd chart uses a sort of standardized flap deflection to make comparison easier. I don't know what the P-40 used for Flap deflection but the Spitfire was around 80 degrees, not 45. Early flaps were pretty much speed brakes or drag producing elements to shorten glide slopes for landing. Land Spitfires ferried to Malta used wooden wedges to hold the flaps at about 20 degrees for take-off.
And also please note that the maximum lift is achieved at an angle of attack ranging from 12 to 28 degrees depending on device/s used which are pretty useless most of the time for take-off, At lower angles of attack some of these devices do offer some improvement, some do not (slats/slots do almost nothing for lift until 12-14 degrees).

And something I just learned is that the Hellcat used Fowler flaps. It's flaps extend as they lower increasing the wing area. They are narrower in cord and do not extend like a P-38s flaps do but they are technically Fowler flaps. WHich points to another problem with armchair (or computer chair) modifications. Not all aircraft used the same basic device/s in the same way. Different percentage of span, different cords (distance front to back), different deflection angles all hung off of different airfoils.
I am no expert, I do NOT know how much these differences affect things, I only know the differences exist.

 

[fastmongrel]

How about a quick conversion of an advanced trainer much like Miles did to produce the M20. Or (its giving me the dry heaves thinking about it) a liquid cooled F4.

 

[Piper106]

Shortround6 Thanks for the charts on flaps. Never realized the significate differences between flap types.

Looks like one of the differences between the navy and the Army fighters is the type of flaps used. As you stated the F6F used Fowler flaps.

The P-40 and the Spitfire/Merlin Seafires used split flaps. The P-51 used camber changing or 'conventional flaps'. The P-47 appears to have been the only single engine US Army fighter to use 'high performance' flaps. Whether they were slotted flaps or whether they meet the definition of Fowler flaps seems to be an issue of disagreement on some RC model boards. (For completeness, the P-38 used Fowler flaps).

 

[Shortround6]

The M 20 was not a conversion, it was a new aircraft and there was a naval version or at least a conversion of one of the prototypes for naval trials. While it gets you a naval aircraft (if it worked) with a Merlin engine actual performance wasn't that different than Wildcat.

If the original intent is to have a Merlin (or Allison) powered fighter for carrier use before the P-51B-D then you are using single stage engines or even single speed engines. Depending on year you have around 1100-1325hp for take-off.

The Liquid cooled plane will be heavier, but it will be faster (less drag). It will have a slightly higher take-off and landing speed due the weight and it may or may not have a poorer climb ( will lower drag leave enough extra power to overcome extra weight in the climb?). Wildcat has height advantage due to two stage supercharger.

Also please note the US Navy may require more fuel on board than the aircraft you don't wish to talk about ( or the Sea Hurricane) and/or the ability to get into the air with at least small drop tanks (50-60 gal) in order to escort the strike aircraft.

A bit like the British the Americans cannot afford specialized aircraft on carriers, they already have 3 types, splitting the fighter group into two different types per carrier was not going to happen and in the early part of the war having different carriers with different aircraft was more by accident than by design. Say the carrier with the liquid cooled superfighter is hit by a submarine torpedo (or just suffers a engine room breakdown) where does that leave the other carrier/s in the task force with their "older" fighters? Granted there was usually a mix but again due to phasing in or out of certain types ) or late war there were enough carriers that task groups had built in redundancy (lots of carriers per task force not 2-4).

 

[Shortround6]

Shortround6 Thanks for the charts on flaps. Never realized the significate differences between flap types........

F4F used Split flaps:

F4U used ?

And it took a few years to get the F4U rated for carrier use even though it was designed for such use by a company that had built carrier aircraft for about 15 years.

And this may NOT be a smooth landing;

He has caught the wire but looks a little high.

 

[tomo pauk]

...
If the original intent is to have a Merlin (or Allison) powered fighter for carrier use before the P-51B-D then you are using single stage engines or even single speed engines. Depending on year you have around 1100-1325hp for take-off.

The Liquid cooled plane will be heavier, but it will be faster (less drag). It will have a slightly higher take-off and landing speed due the weight and it may or may not have a poorer climb ( will lower drag leave enough extra power to overcome extra weight in the climb?). Wildcat has height advantage due to two stage supercharger.
...

The weight of the two-stage R-1830 (complete power-plant) was about the same as single stage V-1710, and 200 lbs less than singer stage Merlin. The single stage V-1650 does not have any power disadvantage vs. two stage R-1830, at any altitude. It will offer 100 HP more at take off that should take care of those 200 lbs extra. It will also provide usable exhaust thrust, unlike what early- to mid-war Western radial installations were doing. Further, even the early V-12 installations were far better when it comes down to use of ram effect (unless they manage to mess it up like at P-39); more speed (lower drag + greater total thrust) will add further benefits to that.

The two stage R-1830 might be among the 1st 2-stage engine in wide use. But they were neither light, nor that powerful. They were not capable to compete with widespread V-12s when it comes down to drag (obviously), over-boosting capability (probably the victim of P&W having more pressing requirements to deal with, but it was still present there), intake ramming. Unfortunately, the F4F never received the ejector exhausts, tight cowling and fan cooling, like at this XP-42.

 

[Shortround6]

Unfortunately, the F4F never received the ejector exhausts, tight cowling and fan cooling, like at this XP-42.

And strangely enough the XP-42 ended it's days without the fan or the ejector exhaust (if it ever had ejector exhaust). It went through 12 different cowl/nose configurations at a minimum. By the time Langley got through playing with the XP-42 it was late 1942 if not later (or they were using it for other research). By the time Langley (or P&W) had figured out the low drag cowling it was much to late to make difference on a R-1830 powered airplane (factories were already tooled up and starting to produce the first R-2800 powered fighters).

 

[tomo pauk]

Going by the link I've provided just above:

... tight cowling and fan cooling, like at this XP-42.

The ejector exhausts were outfitted as early as February 1942 (easy to spot when zoomed), along with cooling fan :
http://www.wisbechaeroclub.co.uk/Scale Drawings/images/C/Curtiss XP-42/Curtiss XP-42(4).jpg
Or maybe as early as Nov 1941 (slots for the exhausts are there, but exhausts themselves cannot be spotted from this angle):
here
Indeed, in 1945, with exhaust marks visible, the XP-42 reverted to 'plain vanilla' collector exhausts:
here

That should also nix the claim that Fw-190 was a guide for the Bearcat engine installation?

 

[R Pope]

Converting a land based plane to carrier ops means band aid strengthening for tail hook and launch stresses, as well as folding wings. Plus as mentioned, more fuel capacity. All that weight has to have a detrimental effect on performance compared to the original land plane. Plus you end up with an older design craft than if you start with a clean sheet of paper.