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Dive Bombing

General

Physical Principles

The aiming point for the bomb release can be calculated, when you know some values.

What you need is:

  • h = Release height above target (1200 m indicated height - 200 m target to sea level = 1000 m)
  • v = aircraft velocity
  • a = dive angle

The general formula for a 90° dive is:

  • h=(g/2*t²)+v*t

By a dive in an angle you have to seperate the horizontal and vertical speed components which results in:

  • v1=v*sin(a)
  • h=(g/2*t²)+v1*t
  • v2=v*cos(a)
  • s=v2*t

Since we don't know the time but our height, we can convert the formula to

  • t=(-v1+√(v1²+2*g*h))/g

With this calculated time we can calculate our horizontal component s.

As an example:

  • v = 450 km/h = 125 m/s
  • h = 700 m
  • a = 60°

Results in:

  • v1 = 108,25 m/s
  • v2 = 62,5 m/s
  • t = 5,23 s
  • s = 326,75 m

With s and h we can now calculate our aim angle ε.

  • ε = atan(h/s) - α
  • ε = atan(700/326,75) - 60° = 4,98°

This means you have to aim ~5° below the Revi-center.

There are 3 points which also influence the aim angle ε.

  • The angle of incidence (aircraft specific, in case of Ju 87 and Ju 88 negligible low)
  • The back-drift of the bomb (see L.Dv. 8/5 aka L.Dv. 20/3)
  • Wind speed and wind direction

Consideration of the back drift distance Δx

You can also calculate the aim angle ε under the consideration of the back drift distance Δx. For this your formula is:

  • ε = 90 - α - tg φ
  • tg φ = Wurfweite(throw length)/Abwurfhöhe(release height) [tg φ = Δx/h]

As example:

Results in:

  • tg φ = 640/950 = 0,675 = 34°
  • ε = 90° - 50° - 34° = 6°

As experience value for the Ju 88 is at dive angles above 50° a value of 1° and below 50° a value of 1,5° to add (in the Ju 88 tables already considered), so for Ju 88

  • ε = 7°

For the usual dive angle and release heights the aim angles are arranged in the following tables.

Ju 87 Dive Tables

Aim Angle

Aim Angle for Ju 87
Release Height = 700 m Release Height = 1000 m
Dive Angle α = Aim Angle ε
60° = 4° 60° = 5,5°
70° = 2° 70° = 3,0°
80° = 1° 80° = 1,5°
Aim Angle For Dive Angle 90° = 0°

Wind Correction Angle

Wind Correction Angle For Ju 87
Dive Angle α Wind Speed in km/h
10,8 18 36 54 72
60° 1,5° 4,5° 6,5° 8,5°
70° 1,5° 4,5° 6,5°
80° 1,5° 4,5°

PC 1000 RS In Ju 87

From L.Dv. T2332/5b (June 1941)

The use of PC-RS bombs is only carried out against battleships, aircraft carrier and heavy cruisers, but not against bedrock emplacements. The use of this special ammunition has to be made only by specially trained groups.

Shall the PC 1000 RS be dropped with the Ju 87, so the Pilot has to use the following table.

The PC 1000 RS must not be dropped by an angle of less than 60°, to prevent bouncing and increase the impact.

Also do not drop the PC 1000 RS with the Ju 87 below 1200 m height, to take advantage of the full impact power.

Attention! Because of self endangerment it is forbidden, at the use of the PC 1000 RS with the Ju 87 after the bomb release to dive further into the old direction or to dive steeper. Delayed flare-out is forbidden.

The A/C has to flare-out simultaneously with the release of the PC 1000 RS.

By usage of PC 1000 RS is the ZSK generally to switch to “v.V.”[full delay].

Release of the PC 1000 RS with swivelling Revi has to be done like the normal bomb attack according to the guidelines of the L.Dv. 20/2. The wind correction angles for the Revi are the same. Only the aim angles at still wind are changing and can be taken from following table:

Aim Angle For PC 1000 RS And Ju 87

Dive angle Release heights
1200 m 1400 m 1600 m
60° 9,5° 10° 11°
70° 5,5°
80° 2,5° 2,5° 2,5°

By wind change additionally the aim angle!

The change for a wind of 100 km/h amounts to:

  • 0,5° for 60° dive
  • 1,5° for 70° dive
  • 2° for 80° dive

At tail wind increase the aim angle by this value, at up wind reduce.

Ju 88 Dive Tables

Aim Angle

Aim Angle for Ju 88
Release Height = 1000 m Release Height = 1500 m
Dive Angle α = Aim Angle ε
40° = 10° 40° = 14°
50° = 7° 50° = 11°
60° = 5° 60° = 8°
70° = 3° 70° = 6°

Wind Correction Angle

For a dive-angle α = 50° and an indicated end-dive-speed of 550 km/h (average dive-speed ~ 430 km/h) accounts the wind-correction-angle for every 10 km/h wind-speed per 1°. At 30 km/h wind therefor 3°.

Dive Bombing Against Swimming Targets (Ju 88)

General

The dive method is the same, also the wind correction. The Pilot has to value course and speed of the target and then select the point for the dive.

As an example:

  • Attack against the wind : 50 km/h
  • Attack in longitudinal ship direction and movement direction
  • Ship: 120 m long, 30 m wide, speed 12sm

Carry out:

  • Approach against the wind in longitudinal ship direction and movement direction.
  • Selecting the initial point of the dive (in our case 3000 m height).
  • Dive time and bomb fall time = 27 s
  • Drive of the ship at 12 sm = 155 m = 1¼ ship's length
  • Dive in 50° angle
    • from chart 1: 50° dive = 7° aim point
    • wind correction: 50 km/h = 5°
    • 7° + 5° = 12° corrected aim point (note: Revi in sketch is dejusted to 9°)
  • At 1400m the wind correction point must be at the bow of the ship
  • Pull the target into the corrected aim point (Not: lower edge of the Revi in sketch), release bomb and continue flare out.

General Instructions:

  • At course change of the target turn in with aileron and at pull-in of the corrected aim point aim left or right, dependent on sense of rotation, of the bow.
  • By attacks with side wind in longitudinal ship direction, what is possible up to 50 sm/h, the initial point must be set sideward to luv
  • Attacks in wind direction are feasible as attacks against wind direction

Prediction Table

Prediction mete for the initial dive point
at height speed of the ship
25 sm 30 sm
5000 m 480 m 560 m
4000 m 390 m 450 m
3000 m 300 m 350 m
ship's lentgh: speed:
battleships and aircraft carrier 200-250 m 25 sm
cruisers 150-180 m 30 sm
merchant ships 100-150 m 12-15 sm

Bf 109

from D(luft)T.229/4 annex 2 (may 1942)

Same aiming principle as Ju 87 but do not exceed the dive angle above 45° (for the Bf 110 temporary). Mortal danger for pilot! (bomb can fall into the propeller circle)

General

Before the dive

  • Propeller to 9:30
  • trim to +2° head heavy

In the dive

  • Throttle to idle
  • Do not exceed a dive angle of 45°
  • At angles above 65° the bomb drops within 0,5 sec into the propeller circle
  • Max. ram pressure near ground at release va = 600 km/h
  • Height difference, which at 9:30 propeller position until achieving of va = 600 km/h near ground in different dive angles and 500 kg bomb load can be dived.
Dive angle Height difference
20° 3000 m
30° 1800 m
45° 1400 m

Note: height difference from initial dive point to release

  • Highest allowed dive speed va = 650 km/h in 1000 m height
  • Highest allowed flare out acceleration = 3,5g
  • Results in smallest flare out radius of 950 m at 650 km/h
  • Lowest release height at 45° dive and 50 m ground clearance: 350 m

Aim Angle

  • For va = 600 km/h
  • Aiming angle at release
Release height
Dive angle 500 m 700 m 1000 m
20° 11° 14°
30° 11°
45°

Wind Correction Angle

Dive angle
20° for every 10 km/h up- or tail-wind ½°
30° for every 10 km/h up- or tail-wind ¾°
45° for every 10 km/h up- or tail-wind 1°

Bf 110

In general the same as for the Bf 109.

Before the dive

  • Propeller to 9:30
  • Trim light head heavy

In the dive

  • Throttle to idle
  • Do not exceed a dive angle of 45° (temporary)
  • Highest allowed dive speed va = 650 km/h
  • Highest allowed flare out acceleration = 3,5g
  • Results in smallest flare out radius of 950 m at 650 km/h
  • Lowest release height at 45° dive and 50 m ground clearance: 350 m
dive.txt · Last modified: 2013/04/29 10:12 by kodoss