High Altitude Heavy Bomber for RAF

Frog said:

And possibly no ammo to save more weight.

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Possibly with no guns?

Standard MiG-15 Armament (most variants):
1 -- 37mm Nudelman N-37 cannon (40 rounds)
2 -- 23mm Nudelman-Suranov NS-23 or NR-23 cannons (80–100 rounds each)

Granted one 23mm with 20 rounds could do the job

Alan Stevens said:

Possibly with no guns?

Standard MiG-15 Armament (most variants):
1 -- 37mm Nudelman N-37 cannon (40 rounds)
2 -- 23mm Nudelman-Suranov NS-23 or NR-23 cannons (80–100 rounds each)

Granted one 23mm with 20 rounds could do the job

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Standard Mig-15s could intercept B-47 with full ammo load - the major problem was ground targeting which was solved (at least - partially) by the use of long-range radar-equipped interceptors (Yak-25). The B-47 was a serious threat for the Soviets, but less dangerous than the U-2.

Could the Sabre have been a viable engine for the high altitude bomber, couple with a suitable turbocharger?

Perhaps with a suitable 2 stage supercharger?

In 1940 the Sabre was around 2,000hp, but by the time of the aircraft's potential production it should be 2,200hp+.

Would 4 be sufficient, or stick with 6?

wuzak said:

Could the Sabre have been a viable engine for the high altitude bomber, couple with a suitable turbocharger?

Perhaps with a suitable 2 stage supercharger?

In 1940 the Sabre was around 2,000hp, but by the time of the aircraft's potential production it should be 2,200hp+.

Would 4 be sufficient, or stick with 6?

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You really need a suitable turbocharger.
Please look at the P&W R-2800 as it had single stage superchargers, two stage mechanical superchargers and two stage with turbo. With a turbo it could make 2000hp at 25,000ft (more or higher later with better turbo and controller) but only 1650hp at 22,500ft(?) with the 2 stage supercharger. It was using 350hp to drive the extra stage. Maybe a better designed extra stage would have used a bit less power? 10-15%?
The Sabre IIA was good for 1880hp at 15,250ft (Lumsden)
The Sabre IIB was good for 2045hp at 13,750ft (Lumsden) using another 150rpm and +11lbs of boost vs 9lbs.
You need to find around 300hp to drive the second stage to get 2000hp in the mid 20s or be happy with around 1700hp?

The Merlin in the Wellington (60 & 62) was good for 1110hp at 29,000ft which was very good altitude performance at it's time. Later versions traded a bit of altitude performance for better power in the low/mid 20s by using a slightly lower gear ratio for high gear.

bf109xxl said:

Standard Mig-15s could intercept B-47 with full ammo load - the major problem was ground targeting which was solved (at least - partially) by the use of long-range radar-equipped interceptors (Yak-25). The B-47 was a serious threat for the Soviets, but less dangerous than the U-2.

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MiG-15s had the speed and altitude capability to intercept a B-47 Stratojet under certain conditions, especially during the early 1950s.

However, doing so with a full ammo load and achieving a successful intercept was challenging due to limited radar guidance and targeting systems on the ground.

The Yak-25, introduced in the mid-1950s, helped address this by incorporating onboard radar and longer range, making it a more capable all-weather interceptor. It was part of the Soviet response to high-speed, high-altitude bombers like the B-47.

As for the U-2, it flew much higher (above 70,000 feet) and was nearly untouchable by early Soviet fighters like the MiG-15 or even the Yak-25. That made it a greater intelligence threat, though not a direct bombing threat like the B-47.

So your statement is broadly accurate: MiG-15s could intercept B-47s under ideal conditions, but targeting was a major limitation, and the U-2 posed a more elusive challenge to Soviet air defenses.

bf109xxl said:

MiGs reached the altitude of the RB-47 at least twice - on April 18, 1955 near the Bering Islands off Kamchatka (the RB-47 was shot down) and on November 7, 1958 over the Baltic Sea off Ventspils (the recon aircraft was damaged).
On May 6, 1954, a pair of MiG-17s from the 1619th IAP of the Northern Fleet tried to intercept a pair of B-47s over the Kola Peninsula. Long-range fire proved ineffective. The repeated attack of another MiG-17 from the 614th IAP was also unsuccessful. Three days later a MiG-17PF tried to intercept an RB-47 near Arkhangelsk without success, but the MiG still reached the altitude of the recon aircraft. For these failures, Lieutenant General of Aviation Borzov, commander of the Northern Fleet aviation, was removed from his post.

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In fact on one of the May 1954 interceptions MiG-17 pilots were more successful than they thought. American pilot colonel Harold "Hal" Austin has reported on the events in the skies over Finland.

On the morning of May 8, 1954, three US Air Force RB-47E Stratojets took off from Britain and headed for the Arctic Ocean. Just over 150 kilometers from Murmansk, two of the planes turned back as planned. However, the third plane, piloted by Harold Austin, continued into Soviet airspace with the intention of photographing military airfields on the Kola Peninsula.

Austin recalled in an article published online at the turn of the millennium how he and his crew had managed to photograph two military airfields from an altitude of 12 kilometers when they were followed by three MiG fighters. Later, more Soviet planes appeared behind them. After the spy plane photographed the fields near Arkhangelsk, it had been in Soviet airspace for an hour and turned southwest towards its last targets. US intelligence had assured the crew that there was no danger from Soviet MiG-15 fighters at the Stratojet's altitude. However, there were new MiG-17 fighters following them. The first Soviet fighter did open fire, causing Austin to dive to gain more speed. The next two MiGs also missed their targets, partly due to fire from the Stratojet's rear cannons. The fourth MiG-17's cannon shells hit the Stratojet's wing.

The spy plane had photographed its last target, and Austin turned the plane west towards Finland "to get the hell out of there." Austin wrote how the pursuers changed to new ones, and the Soviet planes continued to fire in Finnish airspace as well. However, fear of the Stratojet's rear cannons caused the Soviet fighters to stay away from the best firing lines i.e. directly behind the RB. The Soviet pilots did not know that the American plane's guns had already jammed by then. The RB eventually reached the safety of Swedish airspace, where it was no longer followed by Soviet fighters. After an aerial refueling off Norway when the RB was almost out of fuel because of the leaks caused by the hits the plane returned to its base in Britain.

There is a book by Lasnar? about the covert spy flights, mostly by the RAF.

Ps: Fuller story Harold Austin RB-47 Story, page 1 of 3

Alan Stevens said:

So how did he get that high? Probably-- minimal fuel and weight - perfect atmospheric conditions -- a gutsy pilot with nerves of steel -- and maybe a little Cold War bravado.

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And perhaps it was a MiG-17, not a MiG-15. Higher altitude, even if marginally.

Alan Stevens said:

But what were the altitudes of those B-47s?

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Allegedly, the April 17 (or 18), 1955 interception near Kamchatka was at an altitude of 12,500 m. This is according to Russian authors Anokhin and Bykov.

Alan Stevens said:

MiG-15s had the speed and altitude capability to intercept a B-47 Stratojet under certain conditions, especially during the early 1950s.

However, doing so with a full ammo load and achieving a successful intercept was challenging due to limited radar guidance and targeting systems on the ground.

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Once again: both MiG types (doesn't matter, whether -15 or -17) were able to intercept the B-47 successfully with full ammo load if ground targeting functioned properly. It was proved many times - over Kola peninsular, Kamchatka and Caspian sea. Some RB-47 flights over the USSR were initially planned taking into account a typical weakness of the Soviet air defense - insufficient or delayed information exchange between operators from different air defense areas of responsibility.

Alan Stevens said:

As for the U-2, it flew much higher (above 70,000 feet) and was nearly untouchable by early Soviet fighters like the MiG-15 or even the Yak-25.

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Or even MiG-19. Even for the Su-9 the intercept of the U-2 was extremely complicated - _much_ more complicated than that of the RB-47. Indeed, I'm not entirely sure that the average pilot in a Su-9 regiment was capable of intercepting the U-2.

Alan Stevens said:

That made it a greater intelligence threat, though not a direct bombing threat like the B-47.

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By B-47s I meant rather the RB-47, and by threat I meant the possibility of penetrating Soviet airspace.

Alan Stevens said:

So your statement is broadly accurate: MiG-15s could intercept B-47s under ideal conditions, but targeting was a major limitation,

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Accepted with the revision "under typical conditions" instead of "under ideal conditions".

Alan Stevens said:

and the U-2 posed a more elusive challenge to Soviet air defenses.

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More exactly: "a much more elusive challenge".

yulzari said:

At extreme height I recall an Avro Vulcan pilot telling me he had out manoeuvred an F14. A simple matter of wing area. Not operationally relevant for the time as the F14 would be launching missiles at the Vulcan not closing for a gun attack but it was a genuine example of the issues of extreme height interception. He responded to any closing attempts by merely making turns which the F14 could not match without the risk of stalling. This was at @60,000ft. He found the same with RAF Lightnings despite them being able to zoom climb to nearly 88,000ft. But at even approaching those heights they were one direction missiles. Any manoeuvring would stall them out.

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Well, it's actually more a function of stall-speed than wing-area. Turning performance is tied to stall speed since pulling a 2g turn in level flight requires twice the amount of lift as a 1g turn. With dynamic forces increasing to the square of the speed, the square root of the g-load multiplied by the stall-speed gives you the minimum speed you can pull a given load-factor.

Stall-speeds vary with mach number, so at altitude you tend to see stall-speed go up to varying degrees. From what I recall, the F-86A would see stall speeds go up something like 35-40 knots, the F-4's usually see a 15 knot rise at Mach 0.85.

While it's possible to convert indicated/calibrated/equivalent airspeed to true airspeed using a variety of means, this link, as well as this link are pretty good sources (the first is more precise, the second however calculates for CAS and EAS, as well as TAS), at the most basic level, if you know that your plane has a lower stall-speed than your opponent, you can also turn inside of him (and vice-versa if his is lower than you), but if you can convert indicated airspeed to true airspeed, then you could determine the exact rate of turn vai this formula.

A = V^2/R
where...
A = Acceleration (i.e. G-load)
V = Velocity
R = Radius of the turn
(Generally, it's important to use either feet/sec or meters/second with 32.17405 f/s or 9.80665 m/s equal to 1g.)

The Avro Vulcan had a fairly low stall-speed and was capable of going supersonic in dives.

Hi
I have been looking through my files and found there is a better drawing of the Bristol 100-ton bomber of 1942 included in the 'Aeroplane' magazine of September 2009, Database (by Barry Jones):

Also a close up drawing of the coupled Centaurus of the prototype Brabazon:

Mike

Housing two Centurus inside the wing would seem to make the wing rather thick.

MikeMeech said:

Hi
I have been looking through my files and found there is a better drawing of the Bristol 100-ton bomber of 1942 included in the 'Aeroplane' magazine of September 2009, Database (by Barry Jones):
View attachment 837213
Also a close up drawing of the coupled Centaurus of the prototype Brabazon:
View attachment 837214
Mike

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This is very much in the spirit of Giulio Douhet's views on aerial war strategy. A thicker wing? The more fuel it can carry.

wuzak said:

Housing two Centurus inside the wing would seem to make the wing rather thick.

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Hi
Yes, just like the B-36 with its engines in the wings with crew access in flight, no way round that.

Mike

Alan Stevens said:

The Thin Man bomb—an early gun-type nuclear weapon design—ran into a fatal flaw: plutonium-240.

Here's the breakdown:
Design concept: Thin Man was a long, rifle-like bomb intended to fire one subcritical mass of plutonium into another to achieve a nuclear explosion. It relied on plutonium-239 as the fissile material.

The problem: Reactor-bred plutonium inevitably contains plutonium-240, an isotope with a high rate of spontaneous fission. That means it emits neutrons randomly and frequently.

Why that matters: In a gun-type bomb, the two plutonium masses take milliseconds to come together. But with too much plutonium-240, there's a high risk that a stray neutron could trigger a premature chain reaction—a "fizzle"—before full assembly. That would result in a dud or a vastly reduced yield.

Outcome: By mid-1944, Los Alamos scientists realized the gun-type design was unworkable with plutonium. They scrapped Thin Man and shifted focus to the implosion-type design, which became the Fat Man bomb dropped on Nagasaki.

So in short, Thin Man was doomed by the very nature of reactor-produced plutonium.

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The issue was Pu 240, but you're missing that it was Pu 239, an isotope of Uranium 238 that was/is commonly refined in the reactor for both powerplant and weapon development, being more abundant that the alternative Uranium 235, which is found in very small amounts compared to U238 in Uranium ore. Essentially, once refined, Pu239 displays a tendency to attract another neutron to become Pu240, which tends to spontaneously decombust. To this day, U238 refinement is troubled by this, which makes developing nuclear weapons by countries without adequate facilities to do so, so difficult.

A slight correction, Thin Man and Fat Man were being worked on by different teams. Once Thin Man was cancelled, the team led by Deak Parsons and Norman Ramsey then concentrated on Little Boy. The use of U235 enabled a shorter gun length, which was another reason why Thin Man was cancelled; the gun needn't be 17 feet long, so using U235 enabled a shorter gun. Both bombs were being worked on simultaneously as the implosion bomb had already been demonstrated to work, following the Trinity test in July 1945.

GrauGeist said:

Question:
In 1938/39, which British aircraft manufacturer had the most experience (and success) with large aircraft?

Could one of these manufacturers have modified an existing airframe to an upscaled, six engine heavy bomber from that existing design?

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Ask that question within three to four years and you'd get a different answer, because then you have to add, which British company has experience building a reliable and suitable operational four-engined bomber and the answer becomes Avro, without a shadow of a doubt. Handley Page's Halifax is embroiled in engine and airframe issues that means that it has a long way to go before its problems are sorted, then there's Short Brothers, whose Stirling is a credible workhorse, but requires weight loss, a bigger span and an uninterrupted weapon bay to carry bigger RAF bombs that are entering service from 1941 onwards. The Lancaster airframe is by far the best performing RAF four-engined bomber from its introduction into service.

Once the war started, Air Ministry tenders worked on the best entry to the requirement, while taking into consideration how much effort the tender would affect existing war production. If this is the case, then the design chosen would more often than not be farmed to a company without as much work as the parent company. If Avro was busy fulfilling Lancaster orders, then another company would be brought into to do the work. Before the war, things differed a little in that the company has to have the right experience and production facilities to do the job. If the product is successful, the Air Ministry expected facilities available for production to be provided by the manufacturer, although a notable exception was the Hawker Hurricane, which, when an order for 600 Hurris was put out, Hawker simply did not have the production capability, so a new factory was produced and Gloster was bought in to build the type under licence.

An example of a manufacturer not able to fulfil a requirement despite its design winning a tender was Westland and the Whirlwind. Westland had only one factory and its workforce had not built an all-metal aircraft before, not only that but it was building Lysanders to existing orders. Interestingly, Avro winning the P13/36 contract was something of an abberation as Avro had never built a big all-metal bomber before; it gained much experience in sheet metal work from building Blenheims under licence, therefore the Manchester was a huge learning curve for the Avro workforce, whose biggest order up to that point was for Avro Ansons, an aircraft with one foot in the past, being based on the Fokker F.VIIb copy the Avro Ten.

Timing is everything and priorities that wartime introduced certainly changed specifications issued before the war, in many cases rendering them obsolete, even after production began. Aircraft like the Vickers Warwick to B.1/35 found themselves without official interest by the appropriate organisations, even though more than 800 were built.

EwenS said:

The Tiger Force "Special Missions Wing" consisting of the Tallboy equipped 9 & 617 squadrons were expected to be established on Okinawa in time to participate in Operation Olympic scheduled for 1 Nov 1945. The first of two convoys carrying Airfield Construction Service units and their equipment left Britain in mid-July 1945 to travel to Okinawa via the Panama Canal and Pearl Harbor. The first contingent on SS Empress of Australia had reached Eniwetok by mid-Aug where they were held temporarily due to the war ending. They were then diverted to Hong Kong via the BPF base at Manus. Arriving HK in early Sept, they helped re-establish services for the civilian population in the colony.

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That's what Gen Spaatz wanted, but that was not what the British timeline equated to. The two Grand Slam carrying Lancaster squadrons, the Special Missions Wing, were not expected in India until the end of 1945, while the first regular Lancaster squadrons, RAF and RCAF were expected to deploy to Okinawa no earlier than January 1946. As I originally stated, the Tiger Force was intended on a 1946 commencement date.

The RAF had metal frames as standard and a number of designs with metal coverings, the big late 1930's change over was stressed skin. When it comes to big airframes most of the 1930's designs were half weights or less of the 4 engine types under development and trivial compared to the B-29. The big civil flying boats come closest. No company had the production capacity that was going to be required, and they were not going to, wary of a boom bust cycle amid a depression, Douglas had built a pre war amazing total of nearly 250 DC-3 types in the 4 years 1936 to 1939, comparable to the monthly production of either Long Beach or Oklahoma in 1944, or about 100 times the output.

Looking around in 1939, Short, Vickers, Avro and Handley Page are heavily committed to the bomber and other programs, the company with the smallest forward order book for its own designs was Armstrong Whitworth, the Whitley was in production, the Albemarle was their next design, in engineering terms a step backwards from the Whitley in an attempt to avoid using strategic materials. By early 1939 the RAF had enough Hampden, Wellington and Whitley on hand to make judgements on which design had the brightest future. It would take over another 3 years before the RAF had an idea of which of the 4 engine types was better, for Bomber Command in 1942 the Stirling dropped 60.1 tons of bombs per aircraft lost, missing rate 5% of attacking sorties, Halifax 37.7 tons, 6.9%, Manchester 32.2 tons, 7.1%, Lancaster 74.2 tons, 3.7%. Meantime the Mosquito 8.3 tons, 9.9% loss, Blenheim 7.1 tons, 6.9%, the RAF was pushing its new high performance twin too hard. To complete, Wellington 25.2 and 5.3%, Whitley 31.4 and 4.3%, Hampden 17.4 and 5.3%.

Hawker Brooklands was becoming too small for the bigger types being introduced. When it comes to the early Hurricane orders, 527112/36 was for 600, then came 751458/38 for 300, then came 962371/38 for 1,000 (With another 24 added later to replace some aircraft sold to other governments) the first 500 serials were sub contracted to Gloster, then came

964753/38 Canadian Car and Foundry for 40
966177/38 was 20 aircraft removed from the 1936 contract and built for Canada
B19773/39 for 100 was the first direct Gloster contract.

Langley and Gloster built their first Hurricanes in October 1939, Gloster finished in March 1942, Brooklands finished around October 1942, the same time Austin finished its Hurricane order.

Geoffrey Sinclair said:

No company had the production capacity that was going to be required, and they were not going to, wary of a boom bust cycle amid a depression, Douglas had built a pre war amazing total of nearly 250 DC-3 types in the 4 years 1936 to 1939,

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To this must be added the roughly 350 B-18 bombers build from 1937 (Production vs prototypes) into 1940.
Douglas's only other large scale production in the mid/late 1930s was the 129-130 Devastator torpedo bombers.
DB-7 production didn't start until summer of 1939. But even 550 twin engine planes over more than 36 months is just over 15 planes per month which is not much compared to war time production.

Where would the Vickers Windsor fit within this scenario? It first flew in 1943 and was produced against Air Ministry Specification B.5/41 (later modified to Spec. B.3/42) for a high-altitude heavy bomber. I am not sure if it could have handled the Grandslam or what its Bombay looked like.