Old Large Bombers: Dive Bombing

[Jane-DoH]

I remember reading that the Avro Manchester could do a 30-degree diving attack -- dunno how popular a tactic this was; regardless, I do remember reading about a B-17 pilot pulling off a dive-bombing attack in WW2 to nail a ship (http://www.dba-oracle.com/dive_bombing_b_17.htm), though I don't know how steep the dive was.

I'm wondering what's the steepest dive angle these planes could perform routinely?

Douglas A-20 Havoc
(though classified as an attack plane, it was also considered a light-bomber)

Boeing B-17 Flying Fortress

Consolidated B-24 Liberator

North American B-25 Mitchell

Martin B-26 Marauder

Avro Lancaster

Douglas A-26 Invader
(though classified as an attack plane, it was also classified as a light-bomber)

[hval]

Jane,

Not on your list though might be of interest.

The Halifax had a dive bombing role as part of the original specification as a twin engined bomber. When doing the redesign from twin to four Merlin engines Handley Page were able to have the requirements for dive bombing and torpedo carrying removed, but not the wingspan, which was held onto in order to allow catapult launch. Apparently the catapults were a way of removing the costly peace time activity of enlarging airfields. The catapult idea was later cancelled . While no dive bombing angle was specified, a minute of 20 April 1937 by Group Captain R.D. Oxland, Deputy Director of Operational Requirements, notes: 'The angle of dive requirement may be altered from 70° to 25°.vvThis led to a shorter wing span, and a sturdier airframe, than would otherwise have been built . Even so, the dive angle was about 25 Degrees.

Having said that, the specification did change throughout the life time of the Halifax. The Mk III halifax had a longer wing span.

[Jane-DoH]

hval

Not on your list though might be of interest.

The Halifax had a dive bombing role as part of the original specification as a twin engined bomber. When doing the redesign from twin to four Merlin engines Handley Page were able to have the requirements for dive bombing and torpedo carrying removed, but not the wingspan, which was held onto
in order to allow catapult launch. Apparently the catapults were a way of removing the costly peace time activity of enlarging airfields. The catapult idea was later cancelled . While no dive bombing angle was specified, a minute of 20 April 1937 by Group Captain R.D. Oxland, Deputy Director of Operational Requirements, notes: 'The angle of dive requirement may be altered from 70° to 25°.vvThis led to a shorter wing span, and a sturdier airframe, than would otherwise have been built . Even so, the dive angle was about 25 Degrees.

Didn't know that...

[hval]

Jane,

Whilst I think of it, the angle an aircraft would be able to dive at would depend upon the weapon to be released (weight and aerodynamics) as well as the internal characteristics of the bomb bay for the aircraft, the position of the bomb in the bomb bay and how the weapon is/ was released. Fuel load, engine type, propellor blade design would also have an influence on the dive angle allowed.

I haven't said anything about aircraft design as you have asked about specific aircraft. Having written that, how ever, there were significant differences between different models of the same aircraft type.

[hval]

Jane,

In case you don't know, the Lancaster could do corkscrew dives of about 60 Degrees in a an emergency. This could only be done for a maximum of about 230 metres before an overspeed situation occured.

[DX Wombat]

These sites might provide a some information for you although I haven't read through them myself. Manchester, (http://www.historyofwar.org/articles/weapons_avro_Manchester.html) Lancaster. (http://www.avrolancaster.co.uk/)

[Jane-DoH]

hval

Whilst I think of it, the angle an aircraft would be able to dive at would depend upon the weapon to be released (weight and aerodynamics) as well as the internal characteristics of the bomb bay for the aircraft, the position of the bomb in the bomb bay and how the weapon is/ was released. Fuel load, engine type, propellor blade design would also have an influence on the dive angle allowed.

I was thinking mostly of the dive speeds reached, and G-load required to get out of the dive without taking the wings off would be the predominant factor. Though that is admittedly affected by weight.

Still as I understand it most planes have a combat weight which presumes a certain amount of fuel is burned off (with fighters it's 50-60%) by the time the aircraft will engage in combat. Might be more complicated with bombers due to the variations in bomb-loads.

In case you don't know, the Lancaster could do corkscrew dives of about 60 Degrees in a an emergency.

I wouldn't have thought that was possible for such a large aircraft. What kind of G-load did that put on the plane? If I recall a 60-degree bank in level flight is 2.5g, but I don't know what the g-load to recover from a 60-degree dive would be (it would include a lot of variables such as the speed the dive was entered at, the speed the dive was exited at, the altitude the dive was started and terminated)

This could only be done for a maximum of about 230 metres before an overspeed situation occured.

Of the wings or the props?

[proudfishead]

If I recall a 60-degree bank in level flight is 2.5g

Load factor for a straight and level turn is calculated by 1 / Cos(Bank Angle)

i.e. => 1 / Cos 60 => 1 / 0.5 = 2

Therefore, in a 60 degree level turn the load factor would be 2g.

[hval]

Jane,

Of the wings or the props?

Airframe failure.

[Wensleydale]

Wouldn't like to try it in a Manchester..... the aircraft could barely keep level flight on one engine with no bomb load. One lucky pilot managed to get a Manchester back from Germany on one engine after jettisoning everything that was portable (including the guns). He was awarded an immediate DSO!

[Evalu8ter]

The German obsession with dive bombing after the success of the Ju87 in the Blitzkrieg era led the Luftwaffe to specify that the Heinkel 177 should be capable of dive bombing.....as if it didn't have enough issues.....

[NutLoose]

Yup the HE-177 Heinkel Greif, unfortunately the wing wasn't strong enough for the pull outs from the 60 degree dive angle that was envisaged and during the dive the E in it's name managed to drop below the I resulting in the Heinkel coming to Grief on several occasions before the idea was abandoned.

:E

[Brewster Buffalo]

The German obsession with dive bombing...

Other Air Force's took an interest in dive bombing as the precision bombing of its day including the USA. The RAF thought more of strategic bombing rather than tactical support so never put on into service.

[hval]

Brewster,

Even the R.A.F. were keen on dive bombing. Many early specifications required a dive bombing ability. Fortunately this changed.

[FODPlod]

I appreciate it wasn't a 'large bomber' but there was also the Fleet Air Arm's Blackburn Skua although it was built to Air Ministry specifications, not the Admiralty's:Blackburn Skua (http://en.wikipedia.org/wiki/Blackburn_Skua)


The Blackburn B-24 Skua was a carrier-based low-wing, two-seater, single-radial engine aircraft operated by the British Fleet Air Arm which combined the functions of a dive bomber and fighter. It was designed in the mid-1930s, and saw service in the early part of the Second World War...

Built to Air Ministry specification O.27/34, it was a low-wing monoplane of all-metal (duralumin) construction with a retractable undercarriage and enclosed cockpit. It was the Fleet Air Arm's first service monoplane, and was a radical departure for a service that was primarily equipped with open-cockpit biplanes such as the Fairey Swordfish...

Skuas are credited with the first confirmed "kill" by British aircraft during the Second World War: a Dornier Do 18 flying boat was downed over the North Sea on 26 September 1939 by three Skuas of 803 Naval Air Squadron, flying from the aircraft carrier HMS Ark Royal. On 10 April 1940, 16 Skuas of 800 and 803 NAS led by Lieutenant Commander William Lucy, flying from RNAS Hatston in Orkney Islands sank the German cruiser Königsberg in Bergen harbour during the German invasion of Norway. This was the first major warship ever to be sunk by dive bombing, indeed the first major warship ever sunk in war by air attack. Lucy later also became a fighter ace flying the Skua...

In the circumstances, these were considerable achievements.

[Dan Winterland]

The Ju 88 had dive brakes fitted to enable it to dive bomb.

[ORAC]

ya gotta give to those crazy Ivans.......

Russian SPB composite dive bomber...... (http://wio.ru/tacftr/spb.htm)

[mr fish]

i prefer a good TOSS myself :E

[GOLF_BRAVO_ZULU]

In Guy Gibson's splendid book Enemy Coast Ahead (chapter 5, I think), he mentions successfuly dive bombing in a Hampden. A 60 deg dive fom 6,000 ft pulling out at 2,000 ft. He doesn't mention the speed on pull out but he does record that the perspex nose often collapsed "much to the embarrassment of the bomb aimer". I'm sure he mentions trying it again in a Lancaster but I'm damned if I can find my copy.

Just a thought; I remember seeing Shackleton displays that featured a steep descent in coarse pitch. OK, nothing approaching 60 deg but would the props have acted as effective air brakes on a Lancaster with just the 12 blades?

[TBM-Legend]

US NAVAL ORDNANCE AND GUNNERY, VOLUME 2


23E1. Dive bombing

In dive bombing the plane descends toward the target at an angle of 60 degrees or more, thus imparting considerable vertical velocity to the bomb at the moment of release. In a steep dive, with the bomb released at 2,000 to 6,000 feet, time of flight is short and air resistance, wind, and target motion are small. The problem of obtaining accuracy is simplified and a good percentage of hits can be obtained by use of a simple lead-computing sight. A fixed sight and rule-of-thumb methods may also be used.

The plane makes a good AA target, particularly as it pulls out of its dive. In recent aircraft, structural stresses are not too great and a large payload can be carried. Also advantageous is the adverse psychological effect on enemy personnel.

23E2. Glide bombing

Glide bombing is similar to dive bombing except that the attack angle is less than 60 degrees. This technique is better adapted to fighter-type aircraft which tend to develop excessive speeds in steep dives. Glide bombing is high-speed attack and bombs are released at an altitude of from 2,000 to 3,000 feet. Advantages over horizontal bombing include surprise and quick getaway. The disadvantages are that the bomb velocity is less than in dive bombing and AA vulnerability is greater than in dive bombing.

23E3. Dive or glide bombing

The situation obtained in dive or glide bombing under conditions of no wind is represented in figure 23El. At the point of bomb release, the flight line OA is offset from the line of sight to the target, OT, by the angle AOT. This angle intercepts on the ground a distance L, called the linear aiming allowance.


23E4. Skip bombing

In skip or masthead bombing the plane usually attacks at less than 500 feet and the bomb is dropped so close to the target that computation is simple and accuracy high. If the target is a ship, the bomb is released to hit near the waterline just before the plane pulls up to pass over the target. Delay fuzes are employed to give the aircraft time to clear the target. Surprise is highly desirable because the plane is exceedingly vulnerable to AA fire.

23E5. Toss bombing

Toss bombing is a technique wherein the pilot dives his plane directly at the target for a short time and then pulls out. The bomb is released automatically during pull-out, the pull-out maneuver giving the bomb additional forward velocity so that it is tossed above the original LOS and its trajectory intersects the original LOS at the target.

Bombs can be released at higher altitudes than with dive or glide bombing. It necessitates only a short bombing run, but the plane is within effective AA range and is vulnerable during pull-out.

In toss bombing, the airplane is flown initially along a collision course, a straight line path containing the target. If the bomb were released enroute, gravity would cause it to fall short. To overcome this difficulty, the pilot pulls out of his straight-line dive and releases the bomb at a precalculated point along this pull-out curve. The essential geometric features of the problem are indicated in figure 23E2.

The straight-line dive at the target T, here considered to be stationary, is begun at a point above N; pull-out takes place at 0 along the curve OP. If the point P is calculated properly and release of the bomb occurs when this point is reached, the bomb trajectory will intersect the target. In the theoretical development we assume the final velocity of the aircraft in the dive to be reached at the point N; and we assume that this final velocity, which we shall denote by V, remains constant along the timing run NO and the pull-up arc OP.

[cazatou]

With the known unreliability of the Vulture engines fitted to the Manchester I doubt that any sane Pilot would even have considered initiating a dive bombing attack in that Aircraft. The first operational sortie by Manchesters was on 24-25 February 1941 and its final Bomber Command operation was 25-26 June 1942.

[MightyGem]

"much to the embarrassment of the bomb aimer"
More like "much to the consternation of the bomb aimer" I would have thought. :eek:

[GOLF_BRAVO_ZULU]

I thought that, too, about the bomb aimer's reaction. That's what the man wrote, though.

[LowObservable]

We are talking about the dive angle that these aircraft could attain twice, right?

[hval]

LowObservable

We are talking about the dive angle that these aircraft could attain twice, right?

And sometimes even a third time. :E

[walter kennedy]

Didn't the Pathfinders sometimes dive steeply with Lancasters or was it that they were approaching the target accurately at low level? (Can't find the book just now.)

[hval]

From Century of Flight (http://www.century-of-flight.net/Aviation%20history/WW2/bomber%20tactics.htm)

.... This created, by the time the Kammhuber Line was being approached, a mass of aircraft 112 km. (70 ml.) long and some 1,200 m. (4,000 ft.) deep, which, with any luck, completely overwhelmed the Kammhuber defensive box through which it flew. Air gunners had strict orders never to open fire unless attacked as a bomber was more likely to survive by evasion in the dark than by taking the offensive. If attacked, the corkscrew manoeuvre was the best tactic to employ; Martin Middlebrook relates how one German nigh fighter ace followed a corkscrewing Lancaster bomber for three quarters of an hour without once being able to get into a firing position.

[hval]

I have found an interesting article on corkscrewing in a Lancaster; it is on our very own PPRuNe, from February 2007.

Click Here. (http://www.pprune.org/aviation-history-nostalgia/265425-lancaster-corkscrew-manoeuvre-over-rated.html)

An interesting read - as is the link in the thread.

[jamesdevice]

Off -topic, but were the remaining Manchesters scrapped completely or reworked as Lancasters?

[Melchett01]

The German obsession with dive bombing after the success of the Ju87 in the Blitzkrieg era led the Luftwaffe to specify that the Heinkel 177 should be capable of dive bombing

The Germans were obsessed with dive bombing from quite an early time, certainly well before the start of WW2. Len Deighton's book - I can't remember if it was Fighter or Blitzkgreig covered the development of diver bomber TTPs in the 30s. But as well as the Ju-87 and He-177, the Ju-88 was also designated as a dive bomber as far back as 1937. Apparently, it took them until 1943 to realise that the airframe couldn't take the stresses of the pullout at the bottom of the dive, so restricted the dive angle to 45 degrees.

However, one source talks of one airframe being seen with dive angles marked up on the canopy in 10 degree increments from 40-70 degrees of dive :\

1940 | 3422 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1940/1940%20-%203422.html)

[Wensleydale]

Off -topic, but were the remaining Manchesters scrapped completely or reworked as Lancasters?


Those Mancasters still on the order books were delivered as Lancasters. Records of existing Manchesters mostly record "Struck -Off Charge". I assume that Lancasters converted from Manchesters would have kept the original registration number and this would have shown up in the records.

Of interest(?). When 9 Sqn personnel arrived at Waddington to convert to the Lancaster in mid 1942, they carried out the majority of their training in Manchesters until more Lancasters became available. The Manchesters were used for practice bombing and gunnery training with the automatic gun-sight. I have not discovered whether any of these went on operations, but no Manchester losses are recorded for 9 Sqn as far as I am aware.

[hval]

Eventually 200 to 209 Manchesters entered service, before production ended in November 1941. The aircraft was withdrawnm from service June 1942.

193 were operational. Of the 78 aircraft lost, 45 were non-operational losses of which 30 involved engine failure. Later on in its life the Manchester became a fairly effective aircraft once issues with the Vulture engines were resolved.

A good link to read: - Lancaster History (http://www.lancaster-archive.com/lanc_hist.htm)

[Wensleydale]

Eventually 200 to 209 Manchesters entered service, before production ended in November 1941. The aircraft was withdrawnm from service June 1942.



I assume that this date is for operational service - 9 Sqn were using the Manchester for training at the end of August 1942: their first raid with Lancasters was on 10 Sep.

[hval]

Wensleydale,

The last operational trip utilising the Manchester was a bombing raid over Bremen on the 25th June 1942.

Are you sure 9 Sqn flew the Manchester? I know they flew Vickers Wellingtons (Feb 1939-Aug 1942) and that these were replaced by Lancasters in 1942. I have found reference to 9 Sqn using manchesters for trials in 1942 on one web site so far ( Here (http://www.airsceneuk.org.uk/hangar/2001/9sq/9sq.htm)). IX Squadron certainly did not use the Manchester in anger.

Interesting if IX Squadron did carry out trials on the Manchester. Would like to know more.

[Wensleydale]

HVAL,

Sources are "For Faith and Freedom" by John Hamlin (History of Waddington) page 89:

" 9 Sqn moved on 7 August 1942 to Waddington..... Conversion on the new Lancaster began at once, though much training was carried out on the Manchester until enough Lancasters became available. By 20 Aug practice bombing details were being carried out in the Manchesters and air gunners being trained in the use of the automatic gunsight."


and "Bombers First and Last" by Gordon Thorburn (War history of 9 Sqn) Chapter 3 (page 94 in my copy)...

"Pilots began training by flying the Manchester, Bomb aiming had started to become a specialised trade and it was completely so by now with the new, and excellent, semi-automatic Mk 14 bombsight."

W

[Vitesse]

Were the issues with Vultures resolved?

I imagine that merely changing the name might improve the things...

Cheers!

[Fareastdriver]

The Vulture was a pair of Kestrels welded together. The Germans had the similar problem with the Heinkel 177 which had a two pairs of DB 601s welded together.

[hval]

@ Wensleydale,

Thank you for that, appreciated.


@ Vitesse,

Were the issues with Vultures resolved?

Yes they were just about resolved. When the Vulture was cancelled there were no more losses than any other bomber for mechanical failures. The engine was still complex, but they worked. Rolls Royce, unfortunately, did not have the resources available to invest in the development of the Vulture engine when needed. Majority of work was being carried out on the Rolls Royce Merlin instead. Rolls Royce needed the Vulture team to assist in developing the Merlin, which was already a proven power source.