Why the Skua Only Carried a 500lb Bomb

[EwenS]

Everyone seems to have missed the point about wireless communication in the 1930s. A wireless operator was needed because the main form of communication over any distance was by morse code.

The standard RAF TR9 HF voice radio introduced from the early 1930s had a ground to air range of about 35 miles and an air to air range of about 5 miles and was initially difficult to keep tuned in an aircraft without an operator (vibrations etc) until the introduction of a crystal version in 1937. It represented an improvement over previous equipment. On land the RAF managed to increase this for fighter control by the use of relay stations which was not possible at sea.

The RAF only began to introduce VHF voice radio in Oct 1939 (6 Spitfires) which proved an immediate success with ground to air ranges of up to 140 miles and air to air ranges of up to 100 miles at 10,000 feet being achieved. By May 1940 8 Fighter Command squadrons had been equipped increasing to 41 by the end of the year.

As for the homing beacons, the development timeline was as follows:-

Type 72 RN system - trial system in 1933;
Type 72X - introduced to service in early 1936 on a fitting that had to be at masthead
Type 72 DM - allowed radar equipment to be mounted above it. First installation Illustrious completed May 1940

In the US, the first experimental YE beacon was fitted in Saratoga in May 1938. Ranger didn't get her set until her 1941 refit.

 

[tomo pauk]

What, Fulmars?

Obviously, designing a dedicated single-seat carrier fighter would have been the right solution, but as someone said further back in the discussion, they wanted a multi-role type because of limited hangar space... so if they'd done the sensible thing, they might have been stuck with Sea Hurricanes and Skuas and no Swordfish...

Why Fulmars?

I don't know why I thought the Alvis was high-altitude, but I hadn't realised that the Pegasus was improved to the extent it was - you're probably right, in that case!

Main advantage of Pegasus was that it was offered with a 2-speed supercharger (already in 1938), vs. Perseus and Taurus with 1-speed S/C. That meant that, while still making 1000+- HP down low, the power at ~15000 ft was some 880 HP. For comparison, the Perseus engines as used in service were making about 600-680 HP at 15000 ft (Taurus was a bit better, but still much worse than the 2-speed Pegasus, and heavier by 300 lbs).
End result was that high speed of a Skua will be notably better with a 2-speed Pegasus, than with other Bristol's radial of the era (bar Hercules), while not having disadvantages at low altitudes.

 

[planespotting]

Official performance spec was 225mph (196 knots) at 6700 ft with a 500lb. Performance slowly declined above that altitude.

Sometimes performance is stated without using the combat rating of the engine.

What confuses me is that, based on everything that's been said, these figures seem so closely matched to the original Air Ministry specification of 1934, written before an engine was allocated or any design work done.

Asking from sheer ignorance, but is it plausible that they'd hit the target so exactly?

Why Fulmars?

As a joke! Also, because they were what they came up with when they made the decision (in itself correct) to, as you said, "provide some meaningful fighter escort"...

Main advantage of Pegasus was that it was offered with a 2-speed supercharger (already in 1938), vs. Perseus and Taurus with 1-speed S/C. That meant that, while still making 1000+- HP down low, the power at ~15000 ft was some 880 HP. For comparison, the Perseus engines as used in service were making about 600-680 HP at 15000 ft (Taurus was a bit better, but still much worse than the 2-speed Pegasus, and heavier by 300 lbs).
End result was that high speed of a Skua will be notably better with a 2-speed Pegasus, than with other Bristol's radial of the era (bar Hercules), while not having disadvantages at low altitudes.

Who are you who are so wise in the ways of 1930s British radials?!

Okay. I'm convinced. So is there any particular reason not to use them?

 

[SaparotRob]

I like your moxie!

 

[Shortround6]

I like your moxie!

 

[tomo pauk]

As a joke!

Who are you who are so wise in the ways of 1930s British radials?!

As you can see, I'm not that well outfitted between the ears ...

Okay. I'm convinced. So is there any particular reason not to use them?

From my point of view - no.

Also, because they [Fulmars] were what they came up with when they made the decision (in itself correct) to, as you said, "provide some meaningful fighter escort"...

Me, I'd go for a 'big Spitfire' instead of 'small Fairey Battle' in order to make a 2-seat fighter for the FAA; also the engine must be the Merlin XX, not the Merlin VIII. Sorta Supermarine Type 305, but with backseater in place where turret was to go, and with fuel tank between the crew members. Drop tank installation - mandatory.
(historically, the Type 305 was Supermarine's design from August of 1935 for the spec F9/35 from 20th May 1935; obviously, the engine will not be the Mk.X back then, but Mk.II if we're lucky)

 

[Shortround6]

From my point of view - no.

My view also.

But you would have had to steal them at gunpoint (.455 Webley?) from Bomber command as they were the engine of choice for the Hampden and Wellingtons of 1939/40 and part of 1941.

 

[tomo pauk]

But you would have had to steal them at gunpoint (.455 Webley?) from Bomber command as they were the engine of choice for the Hampden and Wellingtons of 1939/40 and part of 1941.

Even when 1-speed Pegasus (be it the high-alt or low-alt versions) is compared with Perseus, the power delivered by Pegasus is better than of the Perseus; Pegasus is cheaper (no sleeve valves); Bristol has the 2-speed drive in the works on Pegasus, but not on Perseus.

FWIW

I'm afraid that there is no comparison where Perseus comes up as a winner.

 

[Shortround6]

I'm afraid that there is no comparison where Perseus comes up as a winner.

You are quite right.
Unfortunately there is also no good substitute for the Pegasus in the twin engine medium bombers (P & W R-1830s or Merlin's ?)
The provision of Enough Pegasus engines for a MK III Skua in place of the 136 Rocs actually wouldn't have hurt Bomber Command much at all.
But Bomber Command didn't play well with others wanted everybody else to play second fiddle to Bomber Command as they destroyed Germany in 1940

Stick the Pegasus in the Skua and you have just about the same capability as the SBD except you have folding wings.

 

[yulzari]

If the Pegasus was in short supply, and Hampdens were sitting around less engines for that reason, then maybe the solution could have been to use Daggers instead? Especially if deHavillend could be consulted on cooling improvements. A ex dH engineer told me many years ago that they looked at the Napier cooling design and concluded that it needed to concentrate more on getting lower pressure exits than on high pressure entry and he thought that dH could have made it work fine and they had plenty of air cooling practical experience.

 

[Geoffrey Sinclair]

So (and correct me if I misunderstand), what this says when it's taken together is that the 1934 specifcation called for 225mph at 6,500ft, that the resulting 1934 design speed was 203 mph at 15,000ft with a Perseus IIS, that most sources quote the specification speed, sometimes hefting the altitude by 200ft, but that a detailed legend raises the slower design speed by a round 10mph to 213 mph with the Perseus XII (still, rather oddly, at 15,000ft rather than its own rated altitude of 6,500ft)? Are those figures likely to be accurate, or are they just estimates created by tinkering with 1934 numbers? Was the Skua, in fact, slower than advertised? Anyone know where 204 mph at sea level comes from? Or 6,700ft rather than 6,500ft?

There are the specifications for what performance is required, then comes testing to see what the actual results are. The data I posted is from "Performance Tables of British Service Aircraft", Air Publication 1746 dated August 1939 but covering until 1941 or so. No graphs, just figures. Includes US built types. Signed off by the Permanent Under-Secretary of State. Since the RAF was only giving one top speed they largely chose 15,000 feet. To determine how much better or worse the Skua did versus the requirements means digging out the details of RAF specification O.27/34.

That's certainly what's claimed in Niall Corduroy's book on the Whirlwind, and I think it's stated in a squadron war diary online somewhere, too. Used against the FW 190 runway at Maupertus and the blockade runner Münsterland, apparently, though 250lb GP bombs were probably not ideal...

Again, commented on above. The Whirlwind was "high altitude" by 1930s standards in terms of being designed to intercept at 15,000ft, rather than 10,000ft, though I can see why that's a confusing turn of phrase...

And I thought that while the Battle could theoretically bomb at a steep angle, the airframe wasn't actually able to get there?

Do you know if the source material with the German comments is available anywhere, out of interest?

And high altitude was well above 10,000 feet by the time the Skua was around. Engines tend to stay in production while they have customers, in Q2/1939 apart from a few Taurus and Hercules, Bristol engine output was roughly 1 Perseus to 2 Pegasus to 4 Mercury. 263 squadron describes its 24 October 1943 attack on the Munsterland as a low level one, the weather that day was bad. Similar restrictions apply to the Whirlwind and the Battle, mostly related to the G forces in any pull out from a dive.

It has been a long time since I read the USSBS reports, the bomb accuracy and notes about duds etc. are in various reports, like the attacks on oil industry targets. Many of the reports are available online.

 

[EwenS]

Oh, I agree, insofar as my knowledge extends. My sense is that in the 1930s, everything was pegged to the idea of bombers trucking along at 10,000ft, so I'm not imagining that they'd be unreasonably smart/ambitious when the Skua was originally designed. No, my point about a new engine is really a question about the potential of the airframe for an upgrade circa 1939 - is it too surreal to talk about a Skua equivalent of a Griffon Spit?

While a re-engining of the Skua may be technically possible, the question would be why you would want to in 1939 considering how aircraft roles for the FAA had developed between 1934 & 1939..

The 1930s began with the FAA having the Hawker Nimrod and Osprey as single and two seat fighters respectively.

1933 Spec S.15/33 issued for a torpedo/spotter/recce aircraft - lead to the Blackburn Shark and Fairey Swordfish
1934 Spec O.27/34 issued for a fighter / dive bomber - lead to Skua
1935 O.30/35 for a two seat turret fighter leading to the Roc


The replacements for these then see a rejuggling of roles.

1936 various proposals for combinations of roles of torpedo/bomber/fighter/recce get cancelled and a replacement Spec 41/36 is issued in early 1937 for a torpedo/spotter/dive bomber/recce aircraft leading to the Fairey Albacore. As a dive bomber it can carry 6x250lb or 3x500lb bombs i.e. 3 times the bomb load of the Skua. Entered service March 1940.

1937 saw that followed up with the issue of Spec S.24/37 that was to combine the roles of dive bomber/recce & torpedo bomber/recce in a single airframe. That led to the Barracuda, which in production Mk.II form could carry 3x500lb bombs as a dive bomber. Again 3 times the load of the Skua and carried faster than the Skua. Had everything gone to plan, which it didn't for a host of reasons, it would have been entering production in April 1941 just as the Skua was leaving service. As I've commented before, due to the torpedo attack profile practiced by the FAA from the 1930s, combining torpedo bomber & dive bomber in a single airframe makes more sense than trying to combine a dive bomber with the fighter role.

As for the fighter element of the Skua role, in 1938 the replacement Spec O.8/38, on an interim basis and for quick production, led to the Fairey Fulmar (256mph in Mk.I form) which entered service in June 1940. That was augmented by an emergency purchase of Sea Gladiators in 1938 as replacements for the Hawker Nimrod of the early 1930s.

Mid-1939 then saw new Specs N.8/39 & N.9/39 issued for a two seat front gunned fighter and a two seat turret fighter respectively, both to have a speed of around 275 knots or 315mph. By the end of he year the RN was having a total rethink about its fighter needs and in Jan 1940 decides on a two seat front gunned fighter under Spec 5/40/F (requirement for a minimum of 300 knots or 350mph) leading to the Fairey Firefly and a single seat fighter to Spec N.11/40 (requirement for 350 knots or 403mph) leading to the Blackburn Firebrand.

So in 1939 with dive bombers with 3 times the bomb load of the Skua already in the pipeline and fighters far faster than the Skua being sought, why would the RN spend time and money on a programme to stick a new engine in the front of an old aircraft design?

Incidentally, Blackburn was one of 5 companies that tendered for the N.8/39 & N.9/39 in 1939. So they had an opportunity to tender a Skua Mk.III as you refer to it, but didn't because it clearly would not have met the requirements that the RN were then looking for. As a fighter that meant an uplift of 90mph in the top speed = 40% increase. That is one hell of an ask for a mid-1930s designed airframe.

 

[SaparotRob]

And one that ugly. C'mon, that windscreen?

 

[MikeMeech]

Hi
The Weir Mission was sent to Canada and the USA in April 1938 to endeavour to purchase additional aircraft for the RAF and FAA. One of the needs was for a FAA fighter armed with 4 MGs, able to carry 2 x 250 lb bombs, having a 2 hour endurance, stalling speed of less than 56 knots, max speed of at least 226 knots, able to take off in a 20 knot wind in 200 ft, wing folding was considered necessary. However none were found to be available in the USA, the US manufacturers were only able/willing to offer the following:

(Info from 'Air Arsenal North America' by Butler and Hagedorn).
So it appears another reason for the orders for the Fulmar replacing the Skua in the fighter role was a lack of alternatives within the timescale required.

Mike

 

[EwenS]

The then latest US naval fighters under development in 1938 would have been the:-

Grumman XF4F-2 - first flight Sept 1937. Max speed 290mph. Lost out to the;
Brewster F2A Buffalo - first flight Dec 1937; first USN production order placed June 1938 with first delivery June 1939.

The Grumman as then developed into the F4F-3 which flew in Feb 1939. This version was ordered by the French Aeronavale and in due course became Martlet Mk.I when the French contract was taken over by Britain in June 1940.

As far as the FAA was concerned neither type was acceptable as the wings were non-folding and the wingspan too great for the new carrier designs about to enter service (Ark Royal & the Illustrious class lifts were 22ft wide).

The main USN fighter types into 1941 were the biplane F2F and F3F. The F2A did not start to arrive with the USN squadrons until June 1940 and the F4F-3 until Dec 1940.

 

[marathag]

A related question is why the Perseus and Mercury both remained in production at the same time given that they had a very similar performance?

Like the Wright R-1820 and P&W R-1830?

 

[marathag]

(Info from 'Air Arsenal North America' by Butler and Hagedorn).
So it appears another reason for the orders for the Fulmar replacing the Skua in the fighter role was a lack of alternatives within the timescale required.

Seversky won the USAAC Fighter competition, after rebuilding this two seater

SEV-2XP X18Y

SEV-1XP, X18Y
In 1935 by removing the gunner and Wright R-1670 Whirlwind and adding retracing gear and a more powerful Wright R-1820 Cyclone.

It was rebuilt one more time for the 1937 Air Races, and had a second seat restored, accessed on the right hand side door

and a more powerful P&W R-1830 Twin Wasp


Northrop did similar, scaling down their multi-seat Gamma to a single seat, fixed gear fighter XFT-1 for Navy, and with retracting gear for the Army competition, the Northrop 3A

 

[marathag]

As for the homing beacons, the development timeline was as follows:-

Type 72 RN system - trial system in 1933;
Type 72X - introduced to service in early 1936 on a fitting that had to be at masthead
Type 72 DM - allowed radar equipment to be mounted above it. First installation Illustrious completed May 1940

In the US, the first experimental YE beacon was fitted in Saratoga in May 1938. Ranger didn't get her set until her 1941 refit.

YE-ZB was a UHF slightly more complex version of the VHF Dot-Dash homing beacons that US airports had been installing since 1928.
IJN used the basic US commercial system, not the barely encrypted YE-ZB system, with basic RDF loop

 

[Shortround6]

Like the Wright R-1820 and P&W R-1830?

Trouble with this comparison is the the American engines were from different companies competing with each other.

The British engines were both from Bristol and were not only completing with each other but with the Bristol Pegasus (a little larger) and the Bristol Taurus (more cylinders and turning a bit faster) so Bristol was splitting it's market 4 ways.

Now perhaps Bristol intended for the Taurus and Perseus to take over from the older Pegasus and Mercury engines if the war hadn't come along?
But Bristol had also underestimated the manufacturing difficulties of the sleeve valve engines and over estimated the development potential (ability to use high boost).

P & W at the end of the 30s was making the R-1535, the R-1830, the R-2180. All 14 cylinder twin row radials. They stopped the R-1535 and R-2180 and stuck with the R-1830 and developed the R-2800 (18 cylinders) instead of trying to tailor their engine selection to suit every aircraft designer. They also develeped the R-2000 which was just a big bore R-1830 and was only used in the C-54/DC-4. They came back with a different R-2180 post war (1/2 of the R-4360) and lost a crap load of money on it. There were too many surplus transport planes around and anybody that money for new planes wanted bigger ones with R-2800s or Wright R-3350s.

 

[Greyman]

What I have re: performance -

Skua L.2888 (8,450 lb) 6,500 ft.
Gills fully closed, rich mixture, 2750 rpm
228 mph

"The correction for position error has not been finally agreed and for this reason the speeds above are approximate only, but are considered to be accurate to within +/- 3 m.p.h."

25 Feb 1939, A. & A.E.E.