An early 2-engined carrier based aircraft - worth the effort?

[Shortround6]

From WIki, take it for what is worth:

" However, the smaller overhead height of the hangars (16 ft (4.88 m) in the upper hangars and 14 ft (4.27 m) in the later ships with lower hangars) compared unfavourably to the 17 feet 3 inches (5.3 m) of the Essex class, 17 ft 6 inches (5.38 m) in Enterprise and 20 ft (6.10 m) in Saratoga."

A Beaufighter tail down may have the prop tips exceed 14 ft in height meaning you can't even turn the engine/s over by hand in the lower hanger let alone run them.

Lift dimensions vary ( and the catapults are useless for a plane the size of a Beaufighter) but 45 feet long and 22 feet wide was the 'standard' size on the Ark Royal ( 2 of that size with one 45 X 25) the Illustrious class ( 2 with 14,000lb capacity), the Indomitable change dthe forward lift to 33 ft wide but kept the 14,000lb rating. The Implacable class got kept the same size lifts but upgraded to 20,000lb capacity and also got catapults that would launch 16,000lbs at 66kts or 20,000lbs at 56kts. (plus the carriers speed plus head wind.)

The Eagle class as designed had catapults that would launch 30,000lbs at 75kts and hadtwo 54 x 44ft lifts that would take 30,000lbs.

Please note that a Beaufighter is around 22ft from outside of cowling to outside of cowling and is much to heavy to handled unless partially loaded by anything short of an Implacable.

The Unicorn and Colossus class have 45 x 33ft lifts but are limited to 15,000lbs (Unicorn 20,000lbs). Catapults were rated at 14,000lb at 66kts and with their 24-25kt top speeds flying off heavy aircraft was harder.

I don't have any figures for the arresting system/s.

 

[Glider]

I'm guessing but the arguments against the Beaufighter whilst valid, would apply to any early twin engine aircraft. As a twin the Beaufighter wasn't big, the Mossie was used post war on carriers and the Corsair was made to fit the UK carriers (with a little trimming I admit) so am sure that if there was a will there would have been a way. The Boston was a bigger heavier aircraft so if she is considered an option then the Beaufighter must be considered a serious contender.

As for the fuel the Ark Royal would seem to have sufficient and the others operated fewer aircraft anyway. I also admit to a bias, here as I have always believed the Ark Royal to be a better balanced design than the Illustrious class.

If you would like a second option then how about a naval version of the Pe 2. Early, good performance and I am sure room for development.

 

[Aozora]

American carrier dimensions:

Hanger deck clear heights:
Lexington Class: 20'
Ranger: 18' 11"
Enterprise Class: 17' 3"
Wasp: 17' 2"
Essex Class: 17' 6"

Elevators; dimensions x lift capacity:
Lexington: 29' 2¼' x 34' 10¼" 6,000 lbs
Ranger: 51' 10¼" x 41' 0¼" 15,000 lbs
Enterprise: 48' x 44' 17,000 lbs
Wasp: 48' x 44' 17,000 lbs
Essex: 48' x 44' 28,000 lbs

Catapults:
Lexington: F Mk II = 10,000 lbs @ 35 mph. Saratoga retrofitted with H Mk 2-1 11,000 lbs @ 70 mph in 73 feet
Ranger: ?
Enterprise Class Wasp: H Mk II 5,500 lbs @ 65 mph in 55 feet; later 7,000 lbs @ 70 mph. Enterprise retrofitted with H Mk 2-1 ditto Saratoga
Essex: H Mk 4A (hangar deck) 16,000 lbs @ 85 mph in 72' 6" acceleration 3.15 G; H Mk 4B (flight deck) 18,000 lbs @ 90 mph in 96' 8" 2.8 G
Mk 4As ordered removed in May 1943

All information from U.S. Aircraft Carriers: An Illustrated Design History: Norman Friedman pages 379 (catapults) 390-394 (other stats)

From this and Shortround's info it should be possible to work out what types of twin-engined aircraft could be reasonably expected to operate from British and American carriers.

If you would like a second option then how about a naval version of the Pe 2. Early, good performance and I am sure room for development.

The Pe-2's wing would need to be completely redesigned to eliminate some vicious low-speed stall charactistics; the F4U used a wing spoiler to help tame the low speed handling, but the problems with the Pe-2 involved the wing section.

 

[Glider]

I can see where you are coming from but it doesn't address the question, if these are the limits then how did the RN operate Mosquitos from RN carriers or come to that the USN operate loaded Avengers which weighed more than 17,000 lb?

The question was An early 2-engined carrier based aircraft - worth the effort? I am saying yes and putting forward the Beaufighter which fits the bill in every way, working on the basis that if you operate a Mosquito from an Illustrious carrier, then you can operate a Beaufighter. Its a simple premise and all the figures in the world cannot alter the simple truth that Mosquitos did operate from the Illustrious class carriers.

The Pe 2 has the performance, doesn't have the weight issues that seem to concern some and has as I said room for development. The Whirlwind is another but not mentioned before as 60rpg isn't enough for a carrier plane, but then again if it could have been modified to say 3 cannon in the nose and 150rpg then you have a contender.

These are better options I would suggest than the DB 7 or P38 which some have mentioned. The X5 I know little about but it seems to good to be true and am cautious about it but would be interested to know what your options are?

 

[wuzak]

Some data from Wiki:

Petlyakov Pe 2
Length: 12.66 m (41 ft 6 in)
Wingspan: 17.16 m (56 ft 3 in)
Height: 3.5 m (11 ft 6 in)
Wing area: 40.5 m² (436 ft²)
Empty weight: 5,875 kg (12,952 lb)
Loaded weight: 7,563 kg (16,639 lb)
Max. takeoff weight: 8,495 kg (18,728 lb)

Mosquito F.II
Length: 41 ft 2 in (13.57 m)
Wingspan: 54 ft 2 in (16.52 m)
Height: 17 ft 5 in (5.3 m)
Wing area: 454 ft2 (42.18 m2)
Empty weight: 13,356 lb (6,058 kg)
Loaded weight: 17,700 lb (8,028 kg)
Max. takeoff weight: 18,649 lb (8,549 kg)

Mosquito B.XVI
Length: 44 ft 6 in (13.57 m)
Wingspan: 54 ft 2 in (16.52 m)
Height: 17 ft 5 in (5.3 m)
Wing area: 454 ft2 (42.18 m2)
Empty weight: 14,300 lb (6,490 kg)
Loaded weight: 18,100 lb (8,210 kg)
Max. takeoff weight: 25,000 lb (11,000 kg)


Beaufighter TF.X
Length: 41 ft 4 in (12.6 m)
Wingspan: 57 ft 10 in (17.65 m)
Height: 15 ft 10 in (4.84 m)
Wing area: 503 ft²[26] (46,73 m²)
Empty weight: 15,592 lb (7,072 kg)
Max. takeoff weight: 25,400 lb (11,521 kg)


Grumman TBF Avenger
Length: 40 ft 11.5 in (12.48 m)
Wingspan: 54 ft 2 in[24] (16.51 m)
Height: 15 ft 5 in (4.70 m)
Wing area: 490.02 ft² (45.52 m²)
Empty weight: 10,545 lb (4,783 kg)
Loaded weight: 17,893 lb (8,115 kg)


Douglas DB-7B/Boston III
Length: 47 ft 11 in (14.63 m)
Wingspan: 61 ft 4 in (18.69 m)
Height: 17 ft 7 in (5.36 m)
Wing area: 465 ft² (43.2 m²)
Empty weight: 15,051 lb (6,827 kg)
Loaded weight: 27,200 lb (12,338 kg)
Max. takeoff weight: 27,200lb (12338 kg)


Lockheed P-38L
Length: 37 ft 10 in (11.53 m) (11.53 m)
Wingspan: 52 ft 0 in (15.85 m) (15.85 m)
Height: 12 ft 10 in (3.91 m) (3.91 m)
Wing area: 327.5 ft² (30.43 m²)
Empty weight: 12,800 lb[119] (5,800 kg)
Loaded weight: 17,500 lb[119] (7,940 kg)
Max. takeoff weight: 21,600 lb (9,798 kg)

 

[Aozora]

I can see where you are coming from but it doesn't address the question, if these are the limits then how did the RN operate Mosquitos from RN carriers or come to that the USN operate loaded Avengers which weighed more than 17,000 lb?

The question was An early 2-engined carrier based aircraft - worth the effort? I am saying yes and putting forward the Beaufighter which fits the bill in every way, working on the basis that if you operate a Mosquito from an Illustrious carrier, then you can operate a Beaufighter. Its a simple premise and all the figures in the world cannot alter the simple truth that Mosquitos did operate from the Illustrious class carriers.

The Pe 2 has the performance, doesn't have the weight issues that seem to concern some and has as I said room for development. The Whirlwind is another but not mentioned before as 60rpg isn't enough for a carrier plane, but then again if it could have been modified to say 3 cannon in the nose and 150rpg then you have a contender.

These are better options I would suggest than the DB 7 or P38 which some have mentioned. The X5 I know little about but it seems to good to be true and am cautious about it but would be interested to know what your options are?

You still haven't explained how effectively the RN could operate an air group which included fully loaded Beaufighters under wartime conditions, given the limited avgas supplies available on RN carriers, and the limited hangar space for what was still a bulky aircraft, even with folded wings; as Shortround has shown, with the limited headspace in the hangar decks it would have been impossible to do anything but maybe park the Beaufighters, and there's no way they could have serviced the engines and test them, which somewhat defeats the purpose of having hangars. Sure, Mosquitoes were used off illustrious class carriers, under peacetime conditions, but the major questions are
1) how many Mosquitoes were loaded onto the carriers?
2) were they stowed/serviced in the hangar decks?
3) what was the maximum number of Mosquitoes that could be deployed per operation?

There's also a question of stowage for spares - for example, British carriers already needed to accommodate several different types of engine; eg: Bristol Pegasus engines (Swordfish), Bristol Mercurys (Skua), R-R Merlins (Fulmars, Sea Hurricanes and [later] Seafires), R-1820s or 1830s (Martlets) etc, etc. - adding the Beaufighter adds yet another bulky radial engine to the supply chain, plus all the requisite spare parts, including the likes of wing panels. How much extra space would be needed, or what other aircraft types would need to be sacrificed to accommodate the smaller number of Beaufighters that could be carried?

Counter questions re; Beaufighters:
Take-off distance required for a loaded Beaufighter? There was no way British catapults could cater for even an empty Beaufighter until the Implacable class, so you're relying purely on the Beaufighter being able to take off under its own steam.

How many Beaufighters could be spotted on deck in addition to the other aircraft types which may have been required for an operation?

With the Beaufighter's need for at least 550 gallons of fuel, how many operations could a British carrier fly before exhausting the avgas supply?

As for US operations, one can almost guarantee that the Avengers either took off without using catapults or, when they did use catapults they operated within the catapult's limits; even fully loaded the Avenger was some 7,000 lbs lighter than a fully loaded Beaufighter.

The Pe-2 would still have required an almost complete redesign to be an effective carrier-borne aircraft. New wings, new undercarriage plus, without new engines, instruments, radio fit, armament, weapons capability etc, there's no way they could have been adapted to operate off British or American carriers without creating yet another major supply chain headache.

 

[Shortround6]

I can see where you are coming from but it doesn't address the question, if these are the limits then how did the RN operate Mosquitos from RN carriers or come to that the USN operate loaded Avengers which weighed more than 17,000 lb?

The RN never operated the Mosquito from a carrier, they did carrier trials in 1944 (landings and take-offs) but the production Sea Mosquitoes ( TR Mk 33) only served in shore based squadrons. The Sea Mosquitoes were also to be equipped with rocket assisted take off gear, two rockets were attached to the fuselage.

The Sea Hornet was used on aircraft carriers but not until the late 40s (47, 48,49) and I don't what modifications, if any, the carriers may have had at this time.

The question was An early 2-engined carrier based aircraft - worth the effort? I am saying yes and putting forward the Beaufighter which fits the bill in every way, working on the basis that if you operate a Mosquito from an Illustrious carrier, then you can operate a Beaufighter. Its a simple premise and all the figures in the world cannot alter the simple truth that Mosquitos did operate from the Illustrious class carriers.

See above, they (the Mosquitoes) did NOT operate from carriers.

The Pe 2 has the performance, doesn't have the weight issues that seem to concern some and has as I said room for development. The Whirlwind is another but not mentioned before as 60rpg isn't enough for a carrier plane, but then again if it could have been modified to say 3 cannon in the nose and 150rpg then you have a contender.

Pe 2 may be a non starter without a whole new wing ( which rather turns it into a different airplane) and the Whirlwind, much as I like it ( and there were two different mock-ups of 4 belt feed cannon noses, no need to drop to 3 guns) might have been just a bit too "hot" for a good carrier plane. Stalling speed for a Whirlwind was about 90/95mph which is around 20mph higher than Spitfire or Corsair or Avenger.

 

[wuzak]

The Sea Hornet was used on aircraft carriers but not until the late 40s (47, 48,49) and I don't what modifications, if any, the carriers may have had at this time.

And they were smaller and lighter.

 

[Glider]

Fair point about the Mossie not operating on the carrier which is a bit of a blow I admit. However the spares I don't see as an issue as the RN would replace one aircraft type with another making the spares situation no worse than before, Merlins and Hercules would do the job. Fuel is always an issue but not on the Ark Royal and the other carriers had smaller air fleets, the Beau is a larger aircraft and it wouldn't be a one to one swap reducing the impact. On size the Corsair is taller and the RN managed them, plus the Avenger wasn't that much lighter than an early Beau and the RN of course used those. Taking off I do see the Beau having to manage on its own but fully loaded B25's did it, so why not? and in RN use the Avengers normally used their own steam, not the catapult.

Re the Pe 2 its early version had problems with low speed handling but it had the ability to be equipped with dive brakes and with some development am confident that this could have been resolved. Saying that it would take a massive redesign I do not go with. It could have been fitted with HMG's which were better than the US 0.5 M2, a bomb is a bomb, a radio can be replaced with a radio, why would it need new engines, undercarriages can be modified and Russian aircraft tended to be robust so I don't see anything massive there.

As an aside I notice no one has come up with any better ideas.

 

[wuzak]

Taking off I do see the Beau having to manage on its own but fully loaded B25's did it, so why not? and in RN use the Avengers normally used their own steam, not the catapult.

The B-25s weren't fully loaded and were somewhat stripped down. The carriers also steamed hard into the wind. Could the RN carriers go as fast?

 

[tomo pauk]

Going with an airplane with 2 Hercules engines might be a little too much, since a plane with 1 Hercules can do all tasks? Stick the Hercules in the future Hawker Henley or Fairey Fulmar, while having a bigger tail wheel strut, for enough clearance while carrying torpedo?

As for proposals other than Beaufighter, the Gloster F.9/37 and naval P-38 were mentioned.

 

[Shortround6]

The Big British carriers were about the same speed as the American carriers or within 0-3kts. Getting 16 planes into the air is NOT operating from a carrier as the planes were not required to land on the carrier or be serviced on the carrier for repeated missions.

As another example of things being not that easy to make land planes operated from carriers a B-25C/D needed about 1000ft of hard runway at 28,000lbs for take-off with a 40 mph head wind ( and 1400ft at 32,000lbs) at 0 degrees C. An A-20B under the same conditions (or 950ft? runway) can have a take-off weight of 19,000lbs. Empty weight was 14,830lbs, Normal gross from a land base was 21,000lb with a 23,800lb max. 21,000lb requires 1200ft of runway with a 40mph headwind at 0 degrees C. Changing the air temperature to 30 degrees C adds another 200ft or more to the runway requirement.

And then you have to get the A-20 back down on the carrier. A-20 lands about 50% faster than the Spitfire or Corsair or Avenger which means each pound of aircraft weight is exerting 225% of the force on the arresting system as each pound of the slower aircraft.

The idea is to get an effective twin, not just to say you could operate a twin from a carrier. The early war carriers were too restricted in size and equipment to permit the operation of effective twins. Every pound counts and twin (even a small one) has a weight penalty over a big single. Consider propellers alone. The Props on the XF5F, if they were the same used on the Brewster Buffalo with the same engine , went just over 300lbs each. Prop on a Corsair or Hellcat (early ones) went about 480-490lbs. The big single while, its parts are heavier, will not require quite the weight in engine and prop controls or engine mounts, it will require fewer instruments, a less complicated fuel system, etc.

 

[merlin]

Surprised, no one has mentioned the French! Whilst on the one hand, their 'War' ended in June 1940, on the other they did issue a spec. for a twin-engine shipboard Recon/torpedo Bomber.
Two, designs were submitted the Dewoitine 750 the C.A.O. 600 - with spans of 52' 54' - still makes them a sizeable addition to the flight-deck. Still interesting that this was attempted, by impossible to know how manageable it would have been.

The other candidate that could have happened would be the Bristol 153a - a twin-engine design to the 'Whirlwind' spec., it had a span of just 37' and mounted 4 x 20 mm cannon.

 

[Shortround6]

OK, lets look at the French aircraft.

Dewoitine 750

And from Wiki;

Empty weight: 2,917 kg (6,431 lb)
Gross weight: 4,272 kg (9,418 lb) (reconnaissance mission)
Max takeoff weight: 4,492 kg (9,903 lb) (torpedo-bomber role)
Powerplant: 2 × Renault 12R air-cooled inverted V12 engine, 370 kW (500 hp) each (take off power)
Maximum speed: 357 km/h; 193 kn (222 mph) at 1,500 m (4,920 ft)
Cruise speed: 240 km/h; 129 kn (149 mph) econ cruise at 1,000 m (3,300 ft)
Bombs: 1 × 650 kg (1,430 lb) torpedo or 4 × 150 kg (330 lb) bombs or 2× 225 kg (500 lb) bombs or 1× 450 kg (990 lb) bomb

C.A.O. 600

Gross weight: 4,700 kg (10,362 lb)
Powerplant: 2 × Gnome-Rhône 14M fourteen-cylinder air-cooled radial engine, 510 kW (680 hp) each
Maximum speed: 380 km/h; 205 kn (236 mph) at 1,500 m (4,900 ft)
Cruise speed: 299 km/h; 162 kn (186 mph) at 1,000 m (3,300 ft) (econ cruise)
Bombs: 1× 650 kg (1,430 lb) torpedo or 4 × 150 kg (330 lb) bombs or 2× 225 kg (500 lb) bombs or 1× 450 kg (990 lb) bomb

What do they offer that a decent ( not even great) single engine torpedo bomber does not?

 

[yulzari]

It may be worth considering what any twin engined aeroplane offers over a big single. Essentially it allows a bigger wing to be dragged around that can lift a heavier warload. At any one moment they could be matched by a large single of the next generation.

Thus the Blenheim offered speed, range and warload that a single could not, at the time it was designed. By 1940 it could be outperformed by a Hercules or Merlin single (I include the Fairey Battle as Fairey wanted it to be a twin and the next generation was the Griffon Firefly).

So the argument for a naval twin must be the same and the overwhelming naval choice was the new big single until the engines had got as big as they had to hand. Only then did they turn to the twin eg F7F, Sea Hornet, Sea Mosquito. But once again the went for the next big single but in jet form.

So was there an early point at which a twin could have a role? It would have to be in the gaps between engine generations. In FAA this would be between the Mercury generation and the Merlin. The actual strike choice was the Pegasus Swordfish but it might have been a twin Mercury Torpedo Bomber to the design of your choice that could operate from a Fleet carrier.

 

[tomo pauk]

OK, lets look at the French aircraft.

Dewoitine 750

C.A.O. 600

What do they offer that a decent ( not even great) single engine torpedo bomber does not?

They offer far better speed than Albacore or Devastator, the torpedo bombers of the same era.

 

[Shortround6]

I should hope so.

The C.A.O. 600 was using 1380hp to haul a 1430lb torpedo.

The Devastator ( which flew 5 years earlier) was using 850-900hp to haul a 2200lb torpedo.

I have no excuse for the Albacore

Devastator had been OUT OF PRODUCTION for several years before the French planes first flew which makes calling them the same era a bit of a stretch.

You want a "what if"? how about a Devastator II with a 1200hp P&W R-1830 engine, flush landing gear and a lower canopy? add a torpedo that works AND can be dropped at a higher speed than 115 mph ( a limitation an American "twin" would have to live or die with)

 

[tomo pauk]

Fair points. The Devastator with a 'proper' Twin Wasp should've been every bit as good as B5N (better?).

Unfortunately, even such a plane will be a lousy fighter, and it will still need the substantial fighter cover. USA does not need to go for 1000-1500 HP twins - they can do better with 2 Twin Wasps or Cyclones. UK can do better, too, as well as Japanese. The French can try with G&R 14N, instead with 14M, or, even better, with Hispano 12Y engines.

 

[Shortround6]

If you go to two "normal" engines ( 900-1300hp for 1940-42) the plane becomes too "big" to be easily accommodated on an aircraft carrier. Please remember that both aircraft AND the carriers were evolving and with build times of 2-3 years (for the Americans, others took longer) for the carriers AFTER design work was done predicting which aircraft would be in service when the carrier/s were finished was a gamble.

An early war "twin" has to fit on and work on an early war carrier. What size and weight planes were planned for carriers to be finished in 1945-46 ( Midway's, British late Eagles and the designed but not built Malta class {45,000tons standard=British Midway}) has little bearing on what the carriers in service in 1940-43 could operate.

You have two conflicting requirements. You want a torpedo bomber that can act as a fighter with the torpedo gone OR you want a fighter that can carry a torpedo. Either way you have a conflict. A 1940-42 aircraft has to have a stalling speed around 70mph or a bit higher, both for take-off and landing. This requires a certain wing loading and that can only be helped to/with a certain amount of wing trickery ( Fowler flaps/ slats, etc.) Please note that Torpedo bombers were required to land back aboard with the unexpended torpedo. ( Land Based Torpedo carrying Beaufighters were expected to land with the torpedo even if it meant jettisoning fuel to get below the max landing weight).
This means your " torp-fighter" will be carrying an extra 1600-2200lbs more while landing than a "normal" fighter which means a bigger wing, heavier landing gear, etc. It has to lug around this "extra" weight/drag when acting as a fighter without the torpedo meaning less performance.

I would also point to the F7F-3N when carrying a torpedo. A gross weight of 25,846lbs with 675 gallons (US) of fuel including a pair of 150 gal drop tanks gave a "range" of 1270 miles at 179mph.

With roughly 60% of the power available a smaller "twin" needs to give up one job or the other. Either be a twin engine torpedo bomber or a twin engine fighter.

 

[tomo pauk]

If you go to two "normal" engines ( 900-1300hp for 1940-42) the plane becomes too "big" to be easily accommodated on an aircraft carrier. Please remember that both aircraft AND the carriers were evolving and with build times of 2-3 years (for the Americans, others took longer) for the carriers AFTER design work was done predicting which aircraft would be in service when the carrier/s were finished was a gamble.

An early war "twin" has to fit on and work on an early war carrier. What size and weight planes were planned for carriers to be finished in 1945-46 ( Midway's, British late Eagles and the designed but not built Malta class {45,000tons standard=British Midway}) has little bearing on what the carriers in service in 1940-43 could operate.

There were real-world examples of sizable aircraft that were handled more or less without problems at the early war carriers. Neither Val nor Dauntless were sporting much of the folding wings (Val's wing tips were folding). Sea Hurricane, F4F-3 again are both sizable and their wings don't fold. Zero's wing tips fold, some variants don't even have that much.
The big Avenger was operating from Independence CVLs. The useful twin does not have to be any bigger than SNCASE SE.100 or Gloster F.9/37.

You have two conflicting requirements. You want a torpedo bomber that can act as a fighter with the torpedo gone OR you want a fighter that can carry a torpedo. Either way you have a conflict. A 1940-42 aircraft has to have a stalling speed around 70mph or a bit higher, both for take-off and landing. This requires a certain wing loading and that can only be helped to/with a certain amount of wing trickery ( Fowler flaps/ slats, etc.) Please note that Torpedo bombers were required to land back aboard with the unexpended torpedo. ( Land Based Torpedo carrying Beaufighters were expected to land with the torpedo even if it meant jettisoning fuel to get below the max landing weight).
This means your " torp-fighter" will be carrying an extra 1600-2200lbs more while landing than a "normal" fighter which means a bigger wing, heavier landing gear, etc. It has to lug around this "extra" weight/drag when acting as a fighter without the torpedo meaning less performance.

We've seen that Avenger did not met several requirements, yet it was accepted for production. Seems like Navy (Navies?) was capable to revise requirements in order to acquire themselves a next-gen aircraft?
The Fowler flaps were used in 2 Lockheeds and Whirly, out of early aircraft. Why not use them where it matters - on a carrier birds? The excessive weight difference between a fighter and a torp bomber can be slightly addressed with gun weaponry layout - install two fixed HMGs, attach 4 HMGs in a fairing/tray/pod instead of torpedo. British can have 4 fixed LMGs, plus 6 detachable.
As for the bulk vs. speed - seems like both Gloster and SNCASE were capable for greater speeds than Zero, S.Hurri or F4F, Firefly, let alone Fulmar. Despite the size.

I would also point to the F7F-3N when carrying a torpedo. A gross weight of 25,846lbs with 675 gallons (US) of fuel including a pair of 150 gal drop tanks gave a "range" of 1270 miles at 179mph.

R-2800 was many things, being frugal was not on of those. Two R-2800s are drunkards.

With roughly 60% of the power available a smaller "twin" needs to give up one job or the other. Either be a twin engine torpedo bomber or a twin engine fighter.

With the power similar to early P-38, Ki-45 or Bf-110, it can do both.