Old Large Bombers: Dive Bombing
 

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, 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)

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.

hval

Didn't know that...

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.

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.

These sites might provide a some information for you although I haven't read through them myself. Manchester, Lancaster.

hval

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.

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)

Of the wings or the props?

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.

Jane,

Airframe failure.

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!

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.....

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

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.

Brewster,

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

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:In the circumstances, these were considerable achievements.

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

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

Russian SPB composite dive bomber......

i prefer a good TOSS myself :E

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?

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.