High Altitude Heavy Bomber for RAF (1 Viewer)

[wuzak]

It's late 1940, the Battle of Britain has come and gone and the newest British bombers, the Manchester, Halifax and Stirling are about to enter service.

Barnes Wallis has proposed a 10 ton (22,000lb) penetrating bomb for attacking mines, dams and the like. Ideally the bomb would be dropped from 40,000ft.

To carry the bomb, Wallis has proposed the 6 engine "Victory" bomber.

The MAP isn't impressed with a single use bomber.

What if the MAP likes the idea of the bomb, but would like more flexibility with the bomb load?

They ask for a high altitude bomber which can carry a single 22,000lb bomb or equivalent in conventional bombs, witha 2,000 mile range with maximum bomb load.

Operating altitude to be above 30,000ft, preferably 40,000ft. A pressurised cockpit is to be used.

Engine options in production are 2 stage Merlins, which were under development in 1940, Hercules and the Vulture, which is soon to be cancelled.

Engines in development, or in early production, include the Napier Sabre, Bristol Centaurus and the Rolls-Royce Griffon.

For the high altitude role, the engines would need to have 2 stage superchargers developed, or be coupled for a turbocharger. I'm not sure US turbos would be available, so the British would have to develop them. Bristol had some experience with turbos in the 1930s.

What engines would be the best option? 4, 6, 8?

Also in 1940, Hawker are researching the new "laminar flow" wings developed by NACA. Ths would lead, eventually, to the Hawker Tempest.

Can this research be used to improve the performance of the high altitude bomber?

What defensive armament will be required?

The Manchester, Halifax and Stirling each have 3 powered turrets, armed with 0.303" mgs.

Are 0.5" hmgs an option?
20mm gun turrets?

For speed of development, remain with manned turrets in preference to remote controlled guns?


Any chance of the bomber being available in 1944?

 

[z42]

Something like the Avro Lincoln, except with two stage Griffons for a bit more power than the historical (Merlin equipped) Lincoln, and pressurized cockpit? Maybe a slightly bigger wing too to reach the altitude?

Though how do normal turrets with pressurizing work? Or are remote controlled ones necessary?

 

[Zmauky]

Some of the answers are in this link ... like Supermarine contemplated 5 engined stratosferic variant of Lancaster.

Lancaster high performance derivatives

I have found a photocopy with this Avro Lancaster high performance derivatives. As a have no source for it I can give no more information. Any help?

www.secretprojects.co.uk

The stratospheric Wellington was also tested. But these were just trials, nothing close to the operational use of the Ju 86P/R.

On the other hand, they probably spent significantly less effort/money etc. probably justified because the Junkers remained a footnote and the USAAF's 8. AF gradually lowered the bombing altitude for the sake of accuracy.

 

[Zmauky]

In terms of armament, the last series of Lancasters received tail turrets with 12.7 Brownig, and the aforementioned Lancaster's successor, Lincoln, also received 20 mm in turrets. So the RAF had a trend (as well as in fighter aviation) to switch to more serious calibers from 7.7 mm.

 

[Admiral Beez]

I like to see what the Short Stirling could do with a wider wingspan and six Merlins.

 

[buffnut453]

Seems like the Supermarine B.12/36 would be the best starting point to achieve the required level of performance.

 

[z42]

Or what of a Mosquito inspired heavy bomber design? If you can cruise at 30k/350mph it would make the plane extremely hard to intercept, making defensive armament unnecessary?

 

[wuzak]

Seems like the Supermarine B.12/36 would be the best starting point to achieve the required level of performance.

That was the same specification that produced the Short Stirling.

Not sure if it would have been powerful enough, nor that it would have a large enough bomb bay for the Grand Slam.

The Lancaster had its large bomb bay due to the requirement of P.13/36 to carry two torpedoes.

 

[yulzari]

Dipping into the store of what was and was tried the high altitude power would be a five Merlin engined device with the fifth engine carried in the fuselage purely as a supercharger driver for the outboard engines.

 

[wuzak]

Dipping into the store of what was and was tried the high altitude power would be a five Merlin engined device with the fifth engine carried in the fuselage purely as a supercharger driver for the outboard engines.

Would 4 Merlins plus a supercharger driving Merlin be enough?

The Victory Bomber was to have 6 Merlins.

With 6 Merlins, would you need 2 supercharger Merlins?

 

[herman1rg]

Dropped from 40,000 Lb?

 

[wuzak]

Dropped from 40,000 Lb?

Oops.

Fixed now.

 

[Admiral Beez]

Could we use RATO type rockets to get our super bomber off the ground, so that it can reach 40,000 feet asap? Or is this too soon?

 

[wuzak]

The Germans certainly used JATO/RATO.

 

[GrauGeist]

The Victory Bomber was to have 6 Merlins.

I found it interesting that Wallis had proposed a bomber and bomb (earthquake) system, but the RAF chose to develop the bomb.

Then they had to figure out a bomber to carry the bomb (which had already been proposed).

 

[don4331]

Reverse engineering the solution: The B-50 has the power to deliver 20,000lb of ordinance at a range of 2k miles from 30k'.

B-29 doesn't, which shows how much difference there still was between estimate and actual for the "Victory Bomber" proposal.​

So, how do you get the 14,000hp of the B-50. Speed without the jets was slightly faster than Victory Bomber specification called for.<With jets over target, considerable better>.

Theoretically, 6 - Griffon 130s will get that for you (you need the 3 speed drive and 2 stages to have the power for a. take off, then b. high altitude).

Centaurus/Sabre/Vulture all need to be reworked with 2nd stage supercharger or turbocharger or auxiliary engine supercharger; Griffon is practically clean sheet development at this point.​

Americans developed the B-29 by '44; my "proposal" is a 6 Griffon version of a RAF equivalent.

 

[wuzak]

I found it interesting that Wallis had proposed a bomber and bomb (earthquake) system, but the RAF chose to develop the bomb.

Then they had to figure out a bomber to carry the bomb (which had already been proposed).

The decision at the time was not to develop the bomb, but the idea was resurrected a couple of years later with the 12,000lb Tallboy and 22,000lb Grand Slam bombs.

The Lancaster could carry the Tallboy with only minor modifications (mainly the bomb bay doors), which were already required to carry the 8,000lb and 12,000lb HC bombs.

 

[z42]

Reverse engineering the solution: The B-50 has the power to deliver 20,000lb of ordinance at a range of 2k miles from 30k'.

B-29 doesn't, which shows how much difference there still was between estimate and actual for the "Victory Bomber" proposal.​

So, how do you get the 14,000hp of the B-50. Speed without the jets was slightly faster than Victory Bomber specification called for.<With jets over target, considerable better>.

Theoretically, 6 - Griffon 130s will get that for you (you need the 3 speed drive and 2 stages to have the power for a. take off, then b. high altitude).

Centaurus/Sabre/Vulture all need to be reworked with 2nd stage supercharger or turbocharger or auxiliary engine supercharger; Griffon is practically clean sheet development at this point.​

Americans developed the B-29 by '44; my "proposal" is a 6 Griffon version of a RAF equivalent.

This might indeed what is required to meet the performance specs. However, IIRC the B-29 project was more expensive than the Manhattan project. Could the UK afford such an expensive project in the middle of a war?

 

[don4331]

This might indeed what is required to meet the performance specs. However, IIRC the B-29 project was more expensive than the Manhattan project. Could the UK afford such an expensive project in the middle of a war?

50% more than the Manhattan project

Parts of that cost are:

Wright Duplex-Cyclones​

Remote control turrets​

Pressurization​

​

And lastly tooling up to build >1,500/yr (plus you have to factor in the modification centers).

The Griffon is less of a technical challenge for RR; and if you stay with manned turrets, the cost is a lot less. And you're replacing a significant portion of 7,500 Lancasters/5,000 Halifaxes/2,000 Short Stirlings.

 

[EwenS]

Could we use RATO type rockets to get our super bomber off the ground, so that it can reach 40,000 feet asap? Or is this too soon?

View attachment 835682

The Germans certainly used JATO/RATO.

RAE Farnborough began investigating the non-projectile use of solid fuelled rockets at the end of 1939.

The outcome was seen firstly in the 'P' (Projectile / Pyrotechnic) Catapult adopted in Jan 1941 and fitted in Fighter Catapult and CAM ships a few months later. These used the standard 3" rocket tubes.

They then moved on to attaching clusters of 3" rocket tubes directly to aircraft. Rocket assisted take offs using a Tiger Moth began around April 1941. By Aug 1941 successful trials with a Whitley led to trials with Stirling I serial N3635. On the latter a pair of jettisonable carriers each holding 12x3" rockets was fitted between the engines, wired up to fire serially in groups of a pair or two at a time. Initial trials were successful.

Then came 18th Aug 1941 and a demonstration for a group of VIPs. The Stirling taxied out, ran up its engines and began its take off run, and the pilot activated the rockets. That was when things went wrong. All the rockets fired together, overstressing the mounts. When the smoke cleared the aircraft was seen to be wrecked. Undercarriage partially collapsed, engines pointing in all directions, 3 props missing. But no one hurt.

Experiments continued but the focus shifted to FAA aircraft, where much use was made of RATOG on escort carriers in 1944/45. Later 5" solid rocket tubes were used.

The Luftwaffe used liquid fuelled rockets to assist getting Me321 Gigant gliders airborne.