A Memorandum on Bombing Policy and its Influence on Design

[wuzak]

In May 1937 George Volkert, then chief designer at Handley Page, wrote a memorandum about the design of future bomber aircraft and the influence that bombing policy would have on design.

In the introduction, he states:

It is the purpose of the following memorandum to show that a drastic revision of present ideas is essential if the utmost performance and destructive power is to be obtained, combined with the maximum economy in the use of highly trained personnel and highly expensive and delicate equipment.

He continues:

It has already been suggested that the future bomber will be provided with no means of self defence other than that arising out of its own very high performance.

From this we can see that the high speed unarmed bomber concept pre-dated the Mosquito by several years.

In the discussion section, Volkert lays out the pros and cons of the unarmed bomber.

• the destructive power afforded by the bomber was greater than at any time before
• that it can be deployed far more rapidly
• that bombing would most likely be against civilian targets
• precision bombing required far greater perfection of equipment and air crew skill than random bomb dropping.
• at the time of writing there was no effective counter-measure against incendiary and gas attacks. It is clear that he thought gas attacks likely.
• the training and supply of highly skilled air crew was thought to be limited. Thus the unarmed bomber with 2, or 3, crew would be more efficient in using the skill base.
• raids would use the clouds over Europe as part of their protection. It was suggested that raids would avoid concentrations of enemy fighters, and that raids would not be sent on clear days. The chance of interception of a high speed bomber operating along these lines was thought to be remote. Radar, of course, changed this.
• close formations of bombers would not be necessary, a loose formation being preferred. There would be two lead aircraft with three crew (pilot, W/T operator, navigator) while the remainder of the aircarft would have two (pilot and W/T operator/navigator). The aircraft would maintain their formation by position keeping using radio signals. Bombing would be done on a signal from one fo the leaders (as the 8th AF ended up doing)
• Vertical storage of bombs was thought better than horizontal storage, as they would remain on or near the CoG. This suggests something like the B-17's bomb bay to me.

In the second part, Volkert puts numbers to his theories, using Specification P.13/36 as a basis.

P.13/36 had three conditions:
(a) 1,000lb bomb load with 1,000 mile range, take-off in 500 yards
(b) 2,500lb bomb load with 2,000 mile range
(c) 3,500lb bomb load, 3000 mile range and accelerated take-off (catapult)

He compared the aircraft and crew required to carry 36,000lb of bombs for loads (a) and (c).

For load case (a)

	P.13/36	New Bomber
No. Aircraft Required	36	12
No. Crew Required	144	24

For load case (c)

	P.13/36	New Bomber
No. Aircraft Required	10	5
No. Crew Required	60	15

Evidently he is assuming different crew requirements for the different tasks.

He concludes by saying that if the same number of bombers were used, the new bomber would carry three times the bombs and use half the crew compared to P.13/36.

He then provides a weight estimation for each type and for the loads carried.
I have only showed the main differences in the weight summary, though he also provides a calculation for tare weight.

Load Case (a)

	P.13/36	New Bomber
Tare Weight (lb)	18350	16447
Crew and Parachutes (lb)	(4) 800	(2) 400
Guns (lb)	144	NIL
Ammunition (lb)	520	NIL
Bombs (lb)	1000	3000
Bomb Gear (lb)	56	168
Oxygen (lb)	117	55
Total Military Load (lb)	2864	3831
Petrol (UKG)	557	529
Petrol (lb)	4289	4070
Oil (lb)	270	260
Total Weight (lb)	25773	24608
Cruising Speed (mph)	278	300

Load Case (b)

	P.13/36	New Bomber
Tare Weight (lb)	18350	16447
Crew and Parachutes (lb)	(6) 1200	(3) 600
Guns (lb)	144	NIL
Ammunition (lb)	520	NIL
Bombs (lb)	2500	5000
Bomb Gear (lb)	140	250
Oxygen (lb)	262	120
Total Military Load (lb)	5069	6254
Petrol (UKG)	1075	1018
Petrol (lb)	8280	7850
Oil (lb)	432	4151
Total Weight (lb)	32131	30966
Cruising Speed (mph)	275	297

Load Case (c)

	P.13/36	New Bomber
Tare Weight (lb)	18350	16447
Crew and Parachutes (lb)	(6) 1200	(3) 600
Guns (lb)	144	NIL
Ammunition (lb)	520	NIL
Bombs (lb)	3500	7000
Bomb Gear (lb)	196	350
Oxygen (lb)	262	120
Total Military Load (lb)	6125	8354
Petrol (UKG)	1605	1515
Petrol (lb)	123660	11670
Oil (lb)	630	595
Total Weight (lb)	37465	37066
Cruising Speed (mph)	273	295

The advantages of the "new bomber" were, according to Volkert:

• A more aeroduynamically refined fuselage
• Minimmal protrusions on outer surface
• The wing can be mounted to the fuselage at the optimum point for reduced drag
• Thinner wing (18% vs 21% for P.13/36)
• Lighter weight due to no turrets, simplified structure, no crew access required in the fuselage, etc, allowing for an increased bomb load
• Lighter weight improves manoeuvrability
• Better crew accomodation and comfort helps the crew become more efficient

 

[davebender]

high speed unarmed bomber concept pre-dated the Mosquito by several years

Britain wasn't alone. Germany reached a similar conclusion resulting in the fast but lightly armed Ju-88.

 

[wuzak]

Britain wasn't alone. Germany reached a similar conclusion resulting in the fast but lightly armed Ju-88.

Is that the same thing?

Was the Ju 88 deliberately lightly armed, or wer hand held rifle calibre machine guns the best defence that could be used at the time?

It did conform to Volkert's ideas in one way - the crew was together in the cockpit.

 

[nuuumannn]

The illustration looked superficially like the He 111 with an all glazed nose and mid mounted wing. The intent of this paper was to shock the Ministry into thinking and acting, rather than as an actual requirement for an aeroplane, and it did the trick, getting many in favour of it, including Liptrot in Research and Ludlow Hewitt, head of Bomber Command, although he made the quote that what the RAF needed was a 'Speed Bomber' and that the 'unarmed' bit was a misnomer - the fast bomber was to be armed after all. This was followed up by Sholto Douglas insisting that the de Havilland DH.98 be fitted with a tail turret. Initially, no one liked the de Havilland design, all thinking - apart from Freeman - that its figures were too optimistic.

The problem with the unarmed bomber idea, despite support it had and discussion it generated, was that the Air Ministry were sold on the powered turret and this did have influence on both B.12/36 and P.13/36, which I mentioned in the other thread was of utmost importance. It fit in with their concepts of what a bomber aeroplane was, whereas the unarmed high speed bomber didn't, despite its virtues. Still, Blackburn managed to slip the B.28 in with a production order without fuss, but it was offered as a high speed cannon armed bomber reconnaissance aircraft from the beginning, which fit with convention. It was never built.

 

[Shortround6]

Is that the same thing?

Was the Ju 88 deliberately lightly armed, or wer hand held rifle calibre machine guns the best defence that could be used at the time?.

A bit of both? While the 4 engine prototype Ural bombers were supposed to have turrets with 20mm cannon I am not sure they were ever fitted. The MG 131 wasn't ready yet and MG FF Cannon were a bit clumsy to try to use hand held. Even the early german turrets in service use were less than Ideal. The first turret used with the MG 131 (single) used manual elevation and power traverse and I am not sure how well the power traverse worked as the turret allowed a small amount of manual traverse too.

One might take the cruise performance of the unarmed bomber with a grain of salt too, as the Manchester rather missed the "proposed" cruise figures of the armed P.13/36 requirement by a fair margin.

 

[stona]

I just think this all reflects mid 1930s thinking. Only Britain and the USA had committed to strategic bombing as a matter of doctrine and really effective strategic bombers needed heavy bomb loads. I happen to think that a typical B-17 or B-24 load was too light (entirely due to the massive weight of their armour and armament) and something in the 8000-10000 pound range should have been a minimum requirement for a strategic bomber by the 1940s.
The limits of 1940s technology meant that a lot of bombs had to be dropped to stand any chance of hitting anything useful. This was true in 1945 as it was in 1939, though things had got a lot better. It was still possible for formations, in daylight, to bomb the wrong city, never mind the wrong target, in 1945.
Even if it was possible to produce a four engine strategic bomber carrying this kind of load the sort of distances this role required at a cruising speed of 275-300 mph, in itself a big ask, it ignores the reality of the 350 mph fighters already in service by 1939. Who's to say that even faster fighters might not have been developed sooner given an extant threat? Not me, but it's the kind of 'what iffery' I don't find helpful.
Cheers
Steve

 

[Shortround6]

The idea that you can make bombers carrying large bomb loads that fly faster than fighters as a general rule isn't going to work. You can get see-saws were for a while (period in time) the bombers may be faster (or fast enough enough to make interception difficult) but the fighters are always going to have an advantage in that they don't have to carry as much fuel in proportion or as much armament.
8000-10,000lb bomb load for 4 engines means 2000-2500lbs of guns and ammo for the fighter. A Lancaster carried 2154 Imp gallons (2586 US gal?)in the wings (?) a B-17 could carry 2800 US gallons in the wings. Even the P.13/36 spec called for 1075 Imp gallons for load condition 'B'. Fighter carries 250-400imp gallons using one bomber engine?
Granted some things don't scale well but the idea that you can make a bomber that outruns fighters using the same engines and technology does't seem to stand up.

 

[stona]

The idea that you can make bombers carrying large bomb loads that fly faster than fighters as a general rule isn't going to work. You can get see-saws were for a while (period in time) the bombers may be faster (or fast enough enough to make interception difficult) but the fighters are always going to have an advantage in that they don't have to carry as much fuel in proportion or as much armament.

Which is why, once you make the commitment to a strategic bombing force history tells us that you are going to have to arm those bombers to defend them and, if operated in daylight, escort them. This makes the high speed, unarmed bomber a dead end born of mid 1930s thinking. It was redundant at it's conception.

In the context of smaller bombers comprising more of a tactical force, as envisioned in German doctrine for example, there might be some room for development but again history shows that it didn't really work here either. The development of the original 'zerstorer' concept implies that the Germans had anticipated this.

Cheers

Steve

 

[Just Schmidt]

Is that the same thing?

Was the Ju 88 deliberately lightly armed, or wer hand held rifle calibre machine guns the best defence that could be used at the time?

It did conform to Volkert's ideas in one way - the crew was together in the cockpit.

The 88 started out as a 'schnellbomber', and at first was unarmed. The third prototype added a raised cabin allowing for dorsal gun(s), the fourth the Gondola. Whether the designers og RLM lost faith in speed as primary defense I'm not sure. Anyway the result, putting on weight and drag, unlike deHaviland to a large extent sabotaged the objective. The V1 and V2 looked quite like the (cleanest of) later Ju 88S, though these didn't quite revert to unarmed.

It seems like the modern breakthrough (smooth skinned monoplanes with retractable gear)happened to bombers before fighters(Polikarpovs I-16 being pretty mutch the exeption). When these caught up, the fast bomber seemed less attractive, radar didn't help. Even the mossie never was the fastest thing in the sky, though hard to intercept. Had all Allied bombers been fast and unarmed, then die Luftwaffe could have consentrated on lighter armed fighters for interceptors, incidentally probably standing a better chance against Escorts. The mossies armed cusins thus helped protect the fewer unarmed bombers. Diversity itself can be an asset.

Still, faster bombers allows for less time to target and better chance of evasion during the redused time in the air, and don't forget AA. And a lot of crew and structural weight is sawed, supported by an effective long range fighter it might have allowed for more effective bombing as it could be done by day. Sure, sometimes even the wrong country might still get bombed, even Our 'smart bombs' sometimes screw up, but who's talking about abandoning bombing? .But even the AR 234 got its fixed rearward cannons. To be honest I have somewhat conflicting info whether the 88 from the outset was to have one defensive gun in the low cabin.

 

[Shortround6]

When the Bristol Blenhiem showed up the British didn't have a single monoplane fighter in service. The Gauntlet Mk II entered service with 56 Squadron and 111 Squadron in May 1936 and was using a 645hp version of the Mercury engine.

First Ju 88 prototype flew in Dec 1936 using DB 600 engines. This is a few months before any Bf 109 prototype gets a DB engine. If your bombers are using engines with 28-30% more power than your fighters then maybe the idea works.

The Russians were not only building I-16s, they were building I-153s and didn't start those until 1939.

Even with retracting landing gear the Biplane is not going to catch a fast monoplane

A few specific examples do NOT make a general trend.

 

[Aozora]

A bit of both? While the 4 engine prototype Ural bombers were supposed to have turrets with 20mm cannon I am not sure they were ever fitted. The MG 131 wasn't ready yet and MG FF Cannon were a bit clumsy to try to use hand held. Even the early german turrets in service use were less than Ideal. The first turret used with the MG 131 (single) used manual elevation and power traverse and I am not sure how well the power traverse worked as the turret allowed a small amount of manual traverse too.

One might take the cruise performance of the unarmed bomber with a grain of salt too, as the Manchester rather missed the "proposed" cruise figures of the armed P.13/36 requirement by a fair margin.

The 20mm armed turrets that were to be fitted to the Dornier Do 19 and Junkers Ju 89 were to be crewed by two men; one would manually control the turret's traverse, while the other would control the elevation of the 20mm MG FF. While the idea probably seemed good at the time, the weight and drag of even one of the turrets seriously degraded aircraft performance. Both the Do 19 and Ju 89 were to be fitted with two of the beasties. In addition, both bombers would require a nine man crew: pilot, co-pilot/navigator, radio operator, bomb aimer and five gunners. As it was, none of the prototypes were fitted with the turrets.

 

[wuzak]

Even the mossie never was the fastest thing in the sky, though hard to intercept. Had all Allied bombers been fast and unarmed, then die Luftwaffe could have consentrated on lighter armed fighters for interceptors, incidentally probably standing a better chance against Escorts. The mossies armed cusins thus helped protect the fewer unarmed bombers. Diversity itself can be an asset.

The Mossie may have not been the fastest thing in the sky, but it was close - at least early in its career.

It was faster on the same engines than the Spitfire. But not as fast as the Mustang - but one wonders what could have been done with an updated Mossie with laminar flow (low drag) wings.

 

[nuuumannn]

I agree with SR and Steve; a four engined fast unarmed bomber is going to have to wait until the jet age. Getting round the concept of what a bomber was is your first hurdle. The age of the modern long range four engined heavy bomber (HP V/1500 anyone?) was dawning in the mid/late 30s and proposals at the time reflected it. Post B.12/36, the British Air Ministry released B.1/39, which has been described as the Ideal Bomber, four engined, 20 mm remotely operated four-gun turret armed heavy bomber. B.8/41 came along (the Vickers Windsor) and in the background companies were working on giant bombers, like the 100 Ton Bomber proposals by Vickers/ Barnes Wallis. The Mosquito, despite Volkert's paper, which I stated was intended to shock the Air Ministry into thinking a bit more, was an aberation to contemporary thought, but thankfully, the bods in the Air Ministry weren't stupid and could see the advantages; they couldn't get enough of them, but the four engined heavy armed with turrets still had its vitally important place.