Why airplanes were designed the way they were.

[Shortround6]

Not to derail an existing thread more than it is already.

It's odd though that the same man who made the Spitfire made these clunky flying boats. I would have expected RJ Mitchell's seaplane to be more like the postwar Supermarine Seagull, but initially with a Merlin. The Griffon-powered Seagull was good for 260 mph!

A lot of things happened in 15-20 years.

The Walrus was designed (over 4 years) to be an improved Seagull Biplane.

Perhaps instead of comparing to later aircraft we should look at what they were replacing and the conditions the plane was operating under.

This was the Walrus predecessor. Also named the Seagull. Note crew positioning for hoisting.
Also there are things that cannot be seen. Like fuel tank/s are in the hull taking up space and preventing or hindering crew swapping places in flight.
Open cockpits. One gun, no bombs.
Wooden hull, for an airplane that was going to get wet a lot.
Tractor propeller which was a hazard to the crew trying to handle the aircraft on water. It was also problem with spray thrown up by the hull.
Turns in History the Seagull was the First (?) British aircraft to be catapulted from a ship. So that was not part of the original requirement, but it was going to be needed in any replacement.
Landing gear was added after original design. It was not well integrated.
Napier engine was state of the art in the early 1920s. Not so much in late 20s or early 1930s.

Walrus was originally known as the Seagull V. It had..........
Metal hull.
Pegasus engine in pusher position.
Retractable landing gear that fitted into the wing (not just got out of the water).
Fuel tank/s above engine to free up hull space.
Enclosed cockpit.
A 500lb bomb load, higher speed and more range/endurance.

Now in the 6-8 years between catapult trials Mitchell and crew had a plane that could launched off of battleships and Cruisers

in a fair variety of sea/wind conditions. However the catapults had limits as to what weight they could get up to what speed. Put a large heavy engine into the plane and you may not reach flying speed before the plane reaches the end of the catapult. There was also limited space on the ships even with folding wings and in 1929-33 very few people were using flaps or high lift devices.

Mitchell and crew were doing this in 1929-33 while working on a few other things at the same time.
The Merlin was in the distant future for most of that time. Supermarine needed planes that could be ordered in 1933-35, not 1936-38.
Engine choices were the Kestrel and in the early years it was usually under 535hp.
The Buzzard, 825hp but large (heavy) and needed a large propeller.
The Pegasus (620hp in early Walrus/Seagull V).

Nobody would have used the "trickery" seen on the 1948 Seagull in the middle 30s.

Full span slotted flaps, with drooping ailerons off of the outer flaps. Large span (debate about full span) leading edge slats
AND you can tilt the wing (adjust the incidence of the entire wing using and electrically operated jack screw attached to the rear spar).
One or two things sure, but all of them?

Can we criticize Mitchell and crew for not designing a Merlin powered monoplane catapult flying boat in the early/mid 30s that could be operated off of existing battleships and Cruisers?
Mitchell may not have been happy with the Walrus as while it was a considerably improvement over the Seagull it didn't reflect all (most?) of the newer stuff from the 1930s. According to Wiki " In February 1936, Mitchell approached the Air Ministry's Director of Technical Development to determine desirable performance attributes in the tentative aircraft prior to the detailed design commencing. From these discussions, it was decided to pursue a dive bombing capability, an elevated loaded weight, longer range, and for it to be fitted with equipment for operating from both aircraft carriers and cruisers."

This resulted in the Sea Otter but due to heavy work loads at several factories and changing requirements the Sea Otter didn't fly until fall of 1938 and production contracts changed back and forth until actual production didn't start until Jan 1943 (the desired Perseus engine had cooling problems and they switched to the old Mercury engine).

Mitchell and most other designers had to operate with what was possible and/or know at the time of the design and be producible in the desired time line. As above, sometimes production was not possible due to design shortages (production drawings) or manufacturing space/capacity. Plenty of designs around the world had to be trashed because hoped for new engines were abject failures under test. In the 1930s even a delay of 2 years could make a plane look at least a generation behind the times.

 

[Admiral Beez]

Plenty of designs around the world had to be trashed because hoped for new engines were abject failures under test.

Good points. IMO, the Gloster F5/34 suffered in prototype trials due to the Mercury engine they were obliged to use instead of the not ready Perseus. Stick a Kestrel onto the Spitfire prototype and see how it goes.

 

[EwenS]

Early British catapult history is not very fully documented.

The first RN ship to be fitted with a catapult was the cruiser, ex-carrier, Vindictive in 1925 with a prototype Carey compressed air catapult. The first RN catapult launch was of a float equipped Fairey IIID on 3rd Oct that year. Further trials took place with float equipped Fairey Flycatchers. After a spell in the Far East 1926-28 the catapult was removed. This catapult had been built at Chatham dockyard and was followed by similar designs on the battleship Resolution in 1926 and sub M2 in 1927.

Catapults of multiple different types began to be more generally fitted to RN warships from about 1930.

There was a prototype RAE designed catapult installed ashore at Farnborough in late 1924 with trials from Dec that year. A variety of aircraft were used in trials including Supermarine Seals (a predecessor of the Seagull III of which a 1926 photo of a catapult accident exists), various Fairey types including the IIID and later IIIF and Parnall Peto.

 

[Shortround6]

The Sea Otter went through 4 propellers in test. A two blade fixed, a 3 blade fixed/? A 4 blade fixed with unequal spacing and finally a 3 blade Rotol constant speed prop.
Getting a prop to transmit the desired power while being compact for easy stowage and not getting hit by too much spray was a complication that ground planes did not have.
In 1935-38 constant speed props in Britain were not as common as they should have been.
The Spitfire 224 was turned down, in part, because it's landing speed was too high, 295sqft for a 4750lb plane. Wing loading just over 16lb/sq/ft. Spitfire wing flap helped landing, it did nothing for take-off. Hurricane flap helped both. Flaps and other high lift devices were undergoing development/transition in the mid 30s. Which design teams trusted them to do what at which month in those several years (finding out you picked the wrong flap and sq ft wing several months into the design process?) is tricky. We know what worked, they were guessing.

 

[Admiral Beez]

I wonder what a bespoke single-seat fighter for the FAA would have looked like. There are very few single-seat FAA aircraft that were not modifications of designs intended foremost for the RAF. The Fairey Flycatcher comes to mind as a FAA-origin design, as well as two of its intended replacements, the well-named Gloster Gnatsnapper and Hawker Hoopoe.

What would a healthy RJ Mitchell have designed if tasked in the late 1930s with making a single-seat monoplane fighter for the FAA? He had good experience in building aircraft that withstood nautical conditions. Hopefully his naval fighter has the landing/takeoff characteristics and robust construction needed along with performance competitive with the coming F4F, A6M, Bf 109, Fw 190, Ki-43 and the likes of the Reggiane Re.2000 and 2002.

 

[EwenS]

In the early 1930s the principal RN floatplane was the Fairey IIIF. While the Seagull V / Walrus is always seen as its successor, it was too heavy for the catapults on many RN cruisers. So the lighter Fairey Seafox had to be developed to a 1932 spec (ff 1936, service entry 1937. About two-thirds the weight of a Walrus. It served until mid-1943 with the last being replaced by Vought OS2U Kingfishers under Lend Lease).

It also became policy to specify that other types should be capable of operation from floats. So Swordfish TSR with floats entered service with a number of RN catapult flights (and saw action at Narvik in 1940 on the battleship Warspite). The Albacore and Roc were tested with floats in 1939/40 (neither successfully) and there was even a proposal for a float equipped Fulmar (dropped in 1939). Note these fighter versions were pre-war and therefore before the Norwegian Campaign of 1940 highlighted the utility of such aircraft, leading to proposals for float equipped Hurricane I and Spitfire I in mid - 1940 (the float equipped Spitfire emerged again later after the outbreak of war in the Far East).

 

[EwenS]

Although it had been known about since before WW1, Supermarine developed its variable incidence wing for its Barracuda competitor, the Type 322, in response to a 1937 spec issued to the industry in Jan 1938. So after Mitchell's death. Due to the pressures of war the prototype Type 322 "Dumbo" didn't fly until 6 Feb 1943. By then it was seen only as a test platform for the wing concept. It was a means of improving aircraft performance overall while still meeting stringent requirements on flight deck limits.

By the time the Supermarine Type 381 Seagull prototypes were ordered in March 1943, the RN had already begun to remove the aviation facilities from its cruisers and capital ships. The last catapult flights were disbanded in early 1944. Its use was then to be from land bases in an ASR role which meant many of the previous catapult restrictions, like weight, didn't apply.

The RN continued to use the Walrus and then the Sea Otter in an ASR role from its carriers until replaced by helicopters during the Korean War. This is a Walrus from 1700 squadron on the escort carrier Ameer in mid-1945

 

[SaparotRob]

.. The Albacore and Roc were tested with floats in 1939/40 (neither successfully)..

I would have thought so. A Roc with floats. Why not add a drogue 'chute too, to get a more stable platform?

 

[pbehn]

The Supermarine Lion II was a state of the art racing plane in 1922.

 

[Shortround6]

What would a healthy RJ Mitchell have designed if tasked in the late 1930s with making a single-seat monoplane fighter for the FAA? He had good experience in building aircraft that withstood nautical conditions

Actually while he had experience with planes in Nautical conditions from a corrosion/weather standpoint, He didn't have much experience designing planes for carrier operations. Aside from using the Seagull/Walrus family from carriers.

Hopefully his naval fighter has the landing/takeoff characteristics and robust construction needed along with performance competitive with the coming F4F, A6M, Bf 109, Fw 190, Ki-43 and the likes of the Reggiane Re.2000 and 2002.

Mitchell was skilled and could see outside the box. He could not perform magic and he could not see into the future or perform Jedi mind tricks to get the Air Ministry to go along with his ideas. Just a year and especially 2 years could make large changes in what engines were favored by the Air Ministry, and what power could be expected from the engines as they changed from 87 octane to 100 octane let alone the change in 1940-41 to 100/130 fuel. "the late 1930s" covers large changes in engines, armament and lift devices in just a few years.

In early 1937 the designer has a choice of .303 machine guns or.................................303 machine guns. Doesn't matter what the aircraft designer thinks aircraft armament should be. Air Ministry may have expressed a desire for 20mm guns but they have not adopted one. In 1938 they have adopted the Hispano gun, bought the license and are building the factory. At this point the Hispano is drum feed only.
The Sabre and Vulture and Griffon engines (the later coming late) were attempts to get high power with 87 octane fuel. So what engine is Mitchell going to design his late 30s fighter around?
Mitchell would also have been working in a vacuum. In the late 30s he would have no knowledge of the A6M or the Ki-43 or the Fw 190. He would have known about the Reggiane 2000 indirectly as the Seversky P-35 and kin. The Reggiane 2000 first flew in May 1939 which is rather late to try to "reply" to. The 109 didn't fly with the DB601 engine until 1938.

This is the XF4F-2 in 1938. Wings with rounded tips and 2 ft shorter on each side (4ft total), round Vertical fin and rudder, round horizontal stabilizer mounted on the fuselage and not on the fin and only two guns, in the cowl. Things changed a lot in 1939. Of interest is the landing gear. Wildcats had just about 1 ft of vertical travel. 2in was used up just sitting on the ground/deck. A lot of land planes had 6-7in of travel. the long travel landing gear gave a lot cushion on arrested landings.

Mitchell had the Spitfire well in hand, but robust construction for carrier use (arrested landings) means more weight. Longer endurance means more weight. Increased ammo capacity means more weight. Landing characteristics are a fine line, you need good control and low speed but not "floaty". Spitfire had a lot of room for improvement to the flap system as the Spitfire flaps were about as simple as they came. But complicated flaps are heavier and more costly to construct. Everything, repeat, Everything is a compromise.

Now a super-duper Supermarine carrier fighter that first flies in 1939 (very late 1930s) could show large advances over a number of other aircraft. Trouble is that it won't enter squadron service until 1941 if you are lucky. The Fulmar was ordered in mid 1938 off the drawing board and entered service in 1940 and it had the advantage of using the P.4/34 bomber as a flying Prototype. The P.4/34 had flown in Jan 1937 so the ordering off the drawing board was rather low risk. I know it is not want is wanted but it speaks to timing.

Now think about what the Navy and/or Air Ministry wanted at the time (late 30s), assuming that they would accept the idea of a single seat fighter. It is not the speed/climb that really matters. It is the desired endurance (fuel load) and armament weight (guns plus ammo) that help govern the wing loading/landing speed. And some of that goes back to operational requirements. Endurance of 2 hours or 3 or 4 hours? firing time of 15 seconds or 23 seconds or 30 seconds. How often will the fighters have to land to refuel/reload?
With time you will get better engines and perhaps better guns (what is known in 1938?) but you will be stuck with the airframe except for minor changes (cutting or adding to the wing a little bit).

Going back to why planes were designed they way they were. F4F-3 wildcat was designed to carry about 37% more fuel than a Hurricane and about 12% more guns (4 .50s) and over double the amount of ammo (even at just 300rpg). This is before armor and SS tanks show up.

Lets also remember that early A6Ms only held 60 rounds per 20mm and were landing during the Battle of Midway for more ammo. Doesn't matter if you have super range/endurance if you only have 7 seconds of firing time for the big guns.

 

[EwenS]

Designers will work with the Spec issued by the customer. That will frequently result in designs with remarkable similarities. Take Spec S.24/37 for an Albacore successor. The contenders:-

From Blackburn (B.29 mockup)

British Spec. S.24/37: naval torpedo/dive bomber reconnaissance aircraft

from Great Britain: in S24/37 specification, for naval torpedo/dive bomber reconnaissance aircraft which led to develope Fairey Barracuda,anther six companies competed in this competition, Shorts S-24 and Percival P-25 were from the rivals. do anyone have a 3-View to them ?.

www.secretprojects.co.uk

From Bristol

British Spec. S.24/37: naval torpedo/dive bomber reconnaissance aircraft

from Great Britain: in S24/37 specification, for naval torpedo/dive bomber reconnaissance aircraft which led to develope Fairey Barracuda,anther six companies competed in this competition, Shorts S-24 and Percival P-25 were from the rivals. do anyone have a 3-View to them ?.

www.secretprojects.co.uk

From Supermarine, the Type 322 "Dumbo"

Supermarine 322

I have liked the look of the Supermarine 322 "Dumbo" since seeing it in Tony Buttler's book and elsewhere. I am also tickled by the fact that the clean, fixed-gear design meant that it faster than the retractable-gear Fairey Barracuda with the same engine. I have often wondered, though, at...

www.secretprojects.co.uk

And the winner from Fairey, the much maligned Barracuda, here in prototype form. At least they managed to make the undercart go up and down.

Or the proposed Fleet Shadower

GAL offering.

O

And the offering from Airspeed

But the same thing happened in the USA.

Curtis SB2C Helldiver

And the Brewster SB2A Buccaneer competitor.

Or the Grumman XTBF-1 Avenger

And its competitor the Vought XTB2U-1 Sea Wolf (eventually produced in small numbers -180- by Consolidated as the TBY-2 Sea Wolf)

Consolidated TBY Sea Wolf - Wikipedia

en.m.wikipedia.org

 

[SaparotRob]

Great info, EwenS. It links design and specs very nicely. It may also be the first time I've seen a pic of a Helldiver with red dot stars and yellow wings.

 

[Shortround6]

The Helldiver was not designed to same specification as the Avenger was. The Helldiver specification pre-dates the torpedo bomber specification. Not sure when the ability to carry a torpedo entered the Helldiver's repertoire. Also the Avenger could not dive bomb (no dive brakes) according to USN doctrine, it could "glide" bomb at maybe 30 degree angle.

 

[Shortround6]

For the RN they needed a 1937 (or very, very early 1938) specification for a single seat carrier fighter. And they needed it be done quickly.
For the sake of this argument (why things were designed the way they were) we need to change the RN thinking a bit just to get to the single seat fighter instead of two seat.

Requirements include take-off and landing speeds/handling and that is peace time requirements, not 1941-43 accident rate acceptability.
Intended carrier usage, which carriers in 1940-41. We can write off the 3 old ones, The Furious and sisters maybe more important. Bad luck and stupidity took two of them out but that was unknown in 1937-38. How many of the 5 new carriers would be available in 1941 in 1937-38 planning? and it what configuration. The Illustrious as planned/built(?) had a 620ft flight deck due the round downs. Later increased to 740ft (?), her two sisters had 670 ft to start and later increased.
What was the "new" doctrine for fighter defense? Last minute scramble or orbiting patrols? How long were the orbiting patrols in hours/endurance? How many times per day was the carrier going to have to turn into the wind to launch/land the orbiting fighters? What altitudes were they expecting attacking bombers to be at? Or expected snoopers? Unexpected is harder
Combat endurance, how many attacks can the fighter make with the onboard ammo. gun time.
How does the fighter get "home"? the 'bespoke' biplane fighters rarely operated out of visual range of the carriers. This worked (maybe, never tested in action) against 110mph torpedo planes. Against 200mph monoplanes that may have been to short a time to get to intercept position.
The radios that worked in the BoB (VHF) didn't exist in 1937-38 and even with radar (being worked on in 1937 but nobody really knew what it could and could not do) even using radios from the carrier (and giving up radio silence) was rather iffy given the HF radio problems of the time. Maybe changes in radio equipment would take care of it, but again, the carrier plane needs more equipment than the land planes do.

Anybody want to take a stab at a 1937 carrier fighter requirement ?
endurance
deck performance
armament/ammo.
Engine choice? really tricky. Desired or planned by Air Ministry and the Air ministry often told the manufacturer what to use, or with historical knowledge? We know that the much favored Taurus crashed and burned, The Hercules never made it into a single engine production aircraft and was way behind in deliveries in 1939-40 and the Big engines were also late/in trouble. Kind of leaves the Merlin as the sole choice but that is with hindsight. It also means that any other choice would be doomed anyway so ?

 

[EwenS]

The Helldiver was not designed to same specification as the Avenger was. The Helldiver specification pre-dates the torpedo bomber specification. Not sure when the ability to carry a torpedo entered the Helldiver's repertoire. Also the Avenger could not dive bomb (no dive brakes) according to USN doctrine, it could "glide" bomb at maybe 30 degree angle.

You have misinterpreted what I wrote. 2 competitions.

Dive bomber - SB2C & SB2A (plus 4 other proposals that were discarded very early on).
Torpedo bomber - TBM & TBU/TBY

Adding a torpedo carrying capability to the SB2C dated back to a Dec 1941 and a suggestion that firstly, with fighter cover now considered essential for a dive bomber, an aircraft could be made lighter & faster by omitting the gunner/radio operator. An extension of this thinking was to combine the roles of TB & DB in a single two seat aircraft. Around the same time VT-3 had been experimenting with torpedo delivery using a diving attack profile but had concluded that to be effective such an approach needed dive brakes and a strong aircraft. A BuAer conference was held 21/22 Jan 1942 to discuss these ideas. From that came approval for Curtiss to develop a single seat dive bomber. Sometime after that BuAer decided to equip the SB2C for torpedo dropping (exact date unknown).

Production SB2C, aircraft c/n 00013, was modified when it came off the production line and was sent for trials at NAS Quonset Point, RI commencing 30 Nov 1942. (Production aircraft 00001 rolled off the line on 30 June 1942).These trials continued until the end of Jan 1943. The biggest problem encountered was the excessive length of time taken to convert the aircraft between roles -

With torpedo fairing fitted - 6 - 7.5 hours
Without torpedo fairing fitted - 3.5 - 5 hours.

This was a problem that also affected the IJN with the B5N-2 Kate TB / level bomber during the early war actions.

Further trials of a torpedo equipped SB2C took place at the Naval Proving Ground, Dahlgren, Virginia from 27 May 1943 and the conclusion was reached that the torpedo mounting equipment needed a redesign, which was apparently carried out satisfactorily but never used in WW2.

And there things lay until late 1944 when ADM Halsey began a push to remove the TBF/TBM from the carriers, favouring a fighter / dive bomber air group, with the DB having a secondary torpedo dropping role. This was at a time when there were fewer & fewer IJN targets worthy of a torpedo and more attacks being made against land targets. In the summer 1945 strikes against Japan no torpedoes were used, even against the surviving IJN warships. The initial Midway class air groups in autumn 1945 on completion consisted of only F4U & SB2C. Had the war gone on into 1946 the TBM would also have been eliminated from CV/CVL air groups on the Essex & Independence classes. More SB2C torpedo dropping trials were being carried out in late 1945 presumably in connection with those changes to the shape of fleet carrier air groups.

For the USN the single seat combined dive & torpedo bomber reached fruition in 1946-48 in the shape of the service entry of the Douglas AD Skyraider & Martin AM Mauler.

It is interesting to note that inter-war the RN had adopted a diving attack torpedo dropping profile ( come in high over the escorts, avoiding long range AA fire, then dive down giving a difficult target for close range AA on target ships, level out, drop the torpedo & escape)and had combined the torpedo and dive bomber roles in the specs that led to the Albacore & Barracuda from 1937, albeit with the need for a three seater.

 

[EwenS]

For the RN they needed a 1937 (or very, very early 1938) specification for a single seat carrier fighter. And they needed it be done quickly.
For the sake of this argument (why things were designed the way they were) we need to change the RN thinking a bit just to get to the single seat fighter instead of two seat.

Requirements include take-off and landing speeds/handling and that is peace time requirements, not 1941-43 accident rate acceptability.
Intended carrier usage, which carriers in 1940-41. We can write off the 3 old ones, The Furious and sisters maybe more important. Bad luck and stupidity took two of them out but that was unknown in 1937-38. How many of the 5 new carriers would be available in 1941 in 1937-38 planning? and it what configuration. The Illustrious as planned/built(?) had a 620ft flight deck due the round downs. Later increased to 740ft (?), her two sisters had 670 ft to start and later increased.
What was the "new" doctrine for fighter defense? Last minute scramble or orbiting patrols? How long were the orbiting patrols in hours/endurance? How many times per day was the carrier going to have to turn into the wind to launch/land the orbiting fighters? What altitudes were they expecting attacking bombers to be at? Or expected snoopers? Unexpected is harder
Combat endurance, how many attacks can the fighter make with the onboard ammo. gun time.
How does the fighter get "home"? the 'bespoke' biplane fighters rarely operated out of visual range of the carriers. This worked (maybe, never tested in action) against 110mph torpedo planes. Against 200mph monoplanes that may have been to short a time to get to intercept position.
The radios that worked in the BoB (VHF) didn't exist in 1937-38 and even with radar (being worked on in 1937 but nobody really knew what it could and could not do) even using radios from the carrier (and giving up radio silence) was rather iffy given the HF radio problems of the time. Maybe changes in radio equipment would take care of it, but again, the carrier plane needs more equipment than the land planes do.

Anybody want to take a stab at a 1937 carrier fighter requirement ?
endurance
deck performance
armament/ammo.
Engine choice? really tricky. Desired or planned by Air Ministry and the Air ministry often told the manufacturer what to use, or with historical knowledge? We know that the much favored Taurus crashed and burned, The Hercules never made it into a single engine production aircraft and was way behind in deliveries in 1939-40 and the Big engines were also late/in trouble. Kind of leaves the Merlin as the sole choice but that is with hindsight. It also means that any other choice would be doomed anyway so ?

Then add in the fact that whatever carrier design you choose the numbers of aircraft are limited. Even the inter-war US carriers only had a single VF squadron of 18 aircraft (plus a few spares triced into the hangar roof and not immediately available). Even Ark Royal while designed around an air group of 72 aircraft (48xTB & 24xHawker Nimrod biplane fighters) entered service in 1938/39 with 60 (42xTSR & 18xSkua fighter / dive bombers).

And that limited number of fighters has to serve a dual purpose. On the one hand fleet air defence (single seat is fine). On the other strike escort and suppression of enemy AA defences (can you make do with a single seater or do you need that second seat to get you to/from the target in anything but clear weather I.e. Pacific v Atlantic operating conditions). So how many do you allocate to each task? What if you find the enemy, launch your strike with fighter escort, and then find yourself under attack? Or the enemy finds you first and destroys part of your fighter force?

Protecting your strike force under armour as in the Illustrious class, albeit at the cost of reduced fighter numbers then has some logic. The alternative as seen by many in the USN is that the carrier becomes virtually a one shot weapon. At minimum the flight deck gets torn up by the enemy (hence the idea of athwartship hangar deck catapults).

As has been said before radar changes everything and that only begins to happen in 1940.

 

[yulzari]

For the RN they needed a 1937 (or very, very early 1938) specification for a single seat carrier fighter. And they needed it be done quickly.
For the sake of this argument (why things were designed the way they were) we need to change the RN thinking a bit just to get to the single seat fighter instead of two seat.

Requirements include take-off and landing speeds/handling and that is peace time requirements, not 1941-43 accident rate acceptability.
Intended carrier usage, which carriers in 1940-41. We can write off the 3 old ones, The Furious and sisters maybe more important. Bad luck and stupidity took two of them out but that was unknown in 1937-38. How many of the 5 new carriers would be available in 1941 in 1937-38 planning? and it what configuration. The Illustrious as planned/built(?) had a 620ft flight deck due the round downs. Later increased to 740ft (?), her two sisters had 670 ft to start and later increased.
What was the "new" doctrine for fighter defense? Last minute scramble or orbiting patrols? How long were the orbiting patrols in hours/endurance? How many times per day was the carrier going to have to turn into the wind to launch/land the orbiting fighters? What altitudes were they expecting attacking bombers to be at? Or expected snoopers? Unexpected is harder
Combat endurance, how many attacks can the fighter make with the onboard ammo. gun time.
How does the fighter get "home"? the 'bespoke' biplane fighters rarely operated out of visual range of the carriers. This worked (maybe, never tested in action) against 110mph torpedo planes. Against 200mph monoplanes that may have been to short a time to get to intercept position.
The radios that worked in the BoB (VHF) didn't exist in 1937-38 and even with radar (being worked on in 1937 but nobody really knew what it could and could not do) even using radios from the carrier (and giving up radio silence) was rather iffy given the HF radio problems of the time. Maybe changes in radio equipment would take care of it, but again, the carrier plane needs more equipment than the land planes do.

Anybody want to take a stab at a 1937 carrier fighter requirement ?
endurance
deck performance
armament/ammo.
Engine choice? really tricky. Desired or planned by Air Ministry and the Air ministry often told the manufacturer what to use, or with historical knowledge? We know that the much favored Taurus crashed and burned, The Hercules never made it into a single engine production aircraft and was way behind in deliveries in 1939-40 and the Big engines were also late/in trouble. Kind of leaves the Merlin as the sole choice but that is with hindsight. It also means that any other choice would be doomed anyway so ?

I think you have explained why they went for a two seater with the range/endurance to recce far or keep a CAP over the fleet. The TAG could find the carrier without compromising radio silence of either party nor tying the carrier to a preplanned route and timing. It was not an either/or in RN eyes but as they could not get a single seat fighter for the close protection task they perforce used the Fulmar that they could get to cover the task. Preferred by the RN would have been a Fulmar and a Sea Spitfire. This releasing the Fulmar to cover the strike role too. Just as they had with the previous set of Osprey and Nimrod and would go on to the Seafire and Firefly.

 

[z42]

I recall reading somewhere that one reason for the RN wanting a two seater fighter was that at the time pilots were RAF, whereas the observer was RN. So in a way insisting on a two seater was a way to ensure the RN got their guy up there.

 

[Shortround6]

Dive bomber - SB2C & SB2A (plus 4 other proposals that were discarded very early on).
Torpedo bomber - TBM & TBU/TBY

You are right. I misinterpreted what you listed.

 

[EwenS]

I recall reading somewhere that one reason for the RN wanting a two seater fighter was that at the time pilots were RAF, whereas the observer was RN. So in a way insisting on a two seater was a way to ensure the RN got their guy up there.

That is probably an apocryphal story.

The issue was one of the standard of navigation training given to RAF pilots. The Official Historian, Denis Richards noted:-

'Except in the coastal reconnaissance squadrons and the few
squadrons with the primary role of night bombing, there had
been too little attention to long distance navigation and blind
flying.'

AND (with my emphasis)

"Training. Prior to 1936, navigation training, except for
pilots destined for flying boat squadrons, was spasmodic and
ineffective. A few officers were admitted to a short navigation
course in which the majority failed to take any great interest;
while specialist training catered for only two officers a year!"

Flying at relatively low levels in open cockpits, an RAF pilot could simply pop below any cloud and find a railway or road or river to find his way home. Try doing that at sea! See Journal 17A for a seminar about RAF Navigation over time.

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That is why the RN felt the need to ensure that there was an RN trained Observer for any aircraft that was destined to fly out of visibility distance of the Fleet. The 1930s began with single seat Hawket Nimrods and two seat Hawker Ospreys as fighters. And remember that those two seat fighters were intended to fulfill a dual role. Fleet protection to supplement the single seaters and AND strike protection accompanying the TB to the target fleet.

Then we have the peculiar situation that until 1939 most (c50%) of the pilots and the TAGs were part of an FAA (i.e. RAF) flight (until 1933) or squadron (after 1933) were RAF and the Observers were always RN and part of the ship's company. So when a squadron left the carrier, the Observers remained aboard to serve the next squadron to arrive. That mentality was further demonstrated by Observers were not given any kind of flying badge.

While the Inskip report of 1937 recommended transfer of the FAA to RN control, that did not happen until May 1939. But a dispute between the services about pilot training was resolved in favour of that remaining with the RAF. But FAA recruits first went on a course teaching them basic Navy skills needed by any prospective officer. That included navigation, morse, semaphore and meteorology and a "spoon & fork" element. Then they were fed into the RAF training system of EFTS & SFTS. Then it was back to RN control to learn the additional skills needed for carrier operations. Observer training remained with the RN throughout, with navigation forming a large part of the courses, along with photography, and air gunnery along with the final "spoon & fork" element.