How fast do dive bombers dive?

Discussion in 'Aviation' started by cherry blossom, May 26, 2014.

  1. cherry blossom

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    OK! Time to admit my ignorance. Dive bombers had dive brakes to keep them from going too fast. So how fast did they dive?
     
  2. Greyman

    Greyman Active Member

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    I don't think dive brakes are effective enough to stop you from reaching your maximum permissible IAS.
     
  3. Ivan1GFP

    Ivan1GFP Member

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    I did a little reading a while back when building models of the SBD-3 Dauntless and the Ju-87B Stuka.
    Simple answer is that it isn't the same with different aircraft.

    The Ju-87 was a "True Vertical Diver" or something to that effect according to Captain Eric Brown. The Dauntless was not. The Dauntless typically dove on its target at an angle of around 70 degrees. From somewhat imprecise memory, the diving speed of the Ju-87 was around 350 mph and it had no trouble keeping the speed down. The SBD would do about 350 up to around 400 mph toward the end of its attack and DID have a bit of trouble keeping its speed down.

    - Ivan.
     
  4. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Read the POH and it will tell you.
     
  5. N4521U

    N4521U Well-Known Member

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    Just untill the skin peals off, then you should pull out!
     
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  6. stona

    stona Well-Known Member

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    The operational requirement for the Ju 87 B was that it should have a safe diving speed of 600 kph (373 mph). This was met with the B-1.

    The normal vertical dive speed of all Ju 87 dive bombers was 350-370 mph.

    Much research was done at the 'Kommando der Sanitatsausbildungs und Ersatzeinheiten der Luftwaffe' (Luftwaffe Medical Training and Replacements Command) in Berlin into the effects of g forces on aircrew using Ju 87s. This would prove valuable to other nations, post war.

    Cheers

    Steve
     
  7. Wildcat

    Wildcat Well-Known Member

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    The A-31 Vengeance would normally "sit" at around 300mph in a vertical dive with dive brakes extended. The airspeed would then build up to the 400mph mark when the bomb bay doors and dive brakes were closed for the pull out at 3000ft.
     
  8. beitou

    beitou Member

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    What happens to the bomb after it is released? Does it follow the same dive angle onto the target, as the bombs aero dynamics are different from the bomber at some point it must surely change its path, is this taken into account when calculating the drop height?
     
  9. davebender

    davebender Well-Known Member

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    Luftwaffe doctrine allowed bombers to dive without dive brakes if enemy air defenses were too intense. This made bombing less accurate but increased survivability. Squadron leader got to make the decision.

    Rudel mentions this in "Stuka Pilot".
     
  10. stona

    stona Well-Known Member

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    A thoroughly unreliable author.

    The dive brakes enabled the Ju 87 to remain within its design limitations in a vertical dive. Without dive brakes I assume Rudel was implying that something less than a vertical dive, with a consequent reduction in accuracy, was used. Unfortunately for him a shallower dive exposes the bomber to greater, not lesser, hazard from anti aircraft fire.

    Does Rudel recall that as Luftwaffe doctrine? It certainly doesn't appear in any other document I've seen relating to dive bombing tactics.

    Cheers

    Steve
     
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  11. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Steve makes perfect points.

    Gentlemen - regardless of what a pilot, any pilot may say, every aircraft has a specified Vne (never exceed speed). Exceed it and you could start bending the airplane and possibly kill yourself. Many of the aircraft mentioned here have flight manuals that could found in this forum. Look them up and examine what their Vne speeds are, your curiosity will be fulfilled! 8)
     
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  12. BiffF15

    BiffF15 Well-Known Member

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    Beitou,

    Here is a short course in "aerial bombing". Forgive any glaring errors as I had this course in August of 1989. An aircraft with WW2 aiming technology (other than the Norden bomb sight) I believe used mostly an illuminated recticle with a center "dot" surrounded by several rings. The dot was a certain width, measured in "mils" but honestly don't remember the definition of a mil. Regardless, for a pilot to drop a bomb on a target his "butt" is required to fly over the target. What's meant by that is the aircraft must be flying a "course" that will take it over the target at the time the pickle button is pressed. Once the device leaves the aircraft it is effected by winds and will have a changing flight path on it's way down.

    From the pilots prespective he will reach his roll in point, or perch, and start his dive. The preferred method is to roll in from a base (or roll in from a perpendicular heading to your target, I.E. it's in your 3 or 9 o'clock when you start), establish your aim point, which in reality is (from the pilots perspective) below the target. As the pilot / aircraft continues the target will march down your windscreen and hopefully at pickle altitude, on your dive angle, at your prescribed speed, with your aircraft completely in trim, you hit the pickle button with the target under your pipper (no wind). And, if miracle of miracles all that occurs your device will hit it's target (or at least with in it's lethal / effective) blast radius.

    In reality there is always winds, and in combat someone will probably be shooting at you. In that case you as the pilot can do one of two things (aiming wise) and they are called mil crank or combat offset. Mil crank means you have some knowledge of the winds and will adjust your pipper to compensate for them. Combat offset (my preffered methond) means you or your flight leads briefs where they are going to aim for known winds, and if they don't audible something else you then correct off their bomb. That means if your lead says he is going to go pipper on at pickle, and his bomb hits at the targets 6 o'clock for 100 meters, then you compensate by putting your pipper at the targets 12 o'clock for 100 when you hit the pickle button.

    Rules of thumb: If you are 1 degree shallow your miss will be greater than if you are 1 degree steep. If you are 1 knot slow your miss will be greater than if you are 1 knot fast. If you pickle 1 foot high your miss will be greater than if you pickled 1 foot low. The message to be gleaned from this is what we called tiger errors. Steep, fast, and press (going below pickle altitude) were MUCH better than the opposite. Also to be picked from this is that if you are a Stuka type aircraft, going straight down, it takes out a LOT of, or minimizes the errors in the equation!

    To answer your questions, after release the "blivot" continues to impact, following a curve linear flight path (curved unless dropped from a 90 degree nose low attitude / perpendicular to the earth). The speed at pickle / release, the altitude, and if known the winds at all altitudes from pickle to impact, form part of the equation of it's flight and success. After you do it for awhile you learn what you historically drop (I dropped mostly short bombs or below the 3-9 line of the target A.K.A beginner bombs) and compensated for it. You also learn that steeper is better, never be slow at pickle, and press a little if you need to (tiger errors). It's fun to do (when no one is shooting at you) and usually the bet takes the better part of 20 minutes to brief (lots of quarters chaning hands in the debrief).

    Cheers,
    Biff
     
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  13. beitou

    beitou Member

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    #13 beitou, May 27, 2014
    Last edited: May 27, 2014
    20 minutes to brief and a lot longer for me to work through. Thank you a good post to explain bomb sightingand aiming.
     
  14. Koopernic

    Koopernic Active Member

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    #14 Koopernic, May 27, 2014
    Last edited: May 27, 2014
    The dive bombing sites used interest me and I would appreciate it if someone shared information on them.

    Initially Stuka's seem to have been aimed simply by diving vertically and lining up the target over markings on the nose. Latter elaborations included automatic pullout devices and a computing bomb site called the Stuvi 5B. The Stuvi 5B could be equipped with a mechanical computer called the BZA (bomb zeil automat) which allowed very shallow 'glide bombing' style approaches if forward visibillity of the aircraft allowed. Stuvi 5B computed the 'hit point' and continuously adjusted the recticle sort of like a gyro site presumably via a light collometer and deflection mirror. Bomb sites such as the Stuvi meant Ju 88 could shallow dive bomb without dive brakes. Incidentally the specified replacement for the Ju 87 Stuka was the Me 410 which included dive brakes, the Stuvi 5B as well as a glass window between the pilots seat.

    The MK XIV bomb sight used on RAF heavy bombers could actually be used in dive bombing although the intention was clearly they be used in shallow dives. Towards the end of the war an attachment for the Norden became available to shallow dive bomb as well.

    At some point radar altimeters entered the picture, I know they were used on the latter USN dive bombers which must have had elaborate dive bombing sights.

    In the Osprey Book "Spitfire versus the V2" the dive bombing technique was to enter a 45 degree dive, aim at the target, then count off (10 usually) during the pullout and release the bombs. It's a bit of an odd book since no V2 site was ever disrupted but does describe the missions.

    On German fighter bombers the ReVi (Reflex Visier) had an adjustable second rectical. The pilot aimed using the normal rectical and pulled up till the second reticule lined up and released. The second rectical was adjusted according to tables from speeds and altitudes of the planned attack.

    A major advance towards the end of the war were the computing toss bombing sites being deployed by the Luftwaffe and USN. The Luftwaffe's TSA2-D the pilot aimed with his normal gun sight, then pulled up, a computer tracked the aircraft's movement using an accelerometer and released them at the appropriate point. Such sights can also release rockets and provide some standoff distance. The TSA2-D took in data from the gryros, airspeed, variometer, altimeter and if available the FuG 101a radar altimeter. The secret to accuracy however was the use of an accelerometer to track the aircraft during the pullup relative to the original line of sight. There is a myth around that the Me 262 would have made a terrible bomber, I suppose it came from Adolf Galland himself, but this bomb site would have made it an accurate delivery system.

    Humans have an amazing ability to track and estimate 'ballistic' objects. Our ancestors needed this skill, the visual processing ability, to swing from tree limb to tree limb and at some point we used throwing objects to defend (like chimpanzees) and latter hunt using spears, rocks, arrows.

    If developed through practice its quite accurate which is why dive bombing from 45 degrees or more was often effective. It seems to explain the male preoccupation with ball games.

    Incidentally, the A-36 (P-51A with dive brakes) was apparently a true vertical dive bomber.

    Hi BiffF15
    "but honestly don't remember the definition of a mil"

    My recollection from reading Walter Dornbergers book on V2 development is that he and von Braun promised 1 mil accuracy for the V2 (A4 then) which was 100 meters at 100km. The figure comes from Artillery and clearly means 1 part in 1000. They chose this number simply because it was twice as accurate as might be expected from the best canon shell. The way they promised to implement this was to use an electronic beam riding system with Doppler tracking of speed and transponder tracking of down range distance. The system was in about its 4th prototype form at the end of the war and known as 'voll zirkel' (full circle). The beam was extremely accurate, the problem was getting rid of (damping out) any residual velocities which caused drift.
     
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  15. Koopernic

    Koopernic Active Member

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    When Yamato was attacked by Helldivers vertical dives were used to minimize exposure to defensive fire as this minimised the exposed area of the aircraft. The defensive fire would have been coming from Yamato herself. However in the case of attacking land target AAA might more likely have been coming from the side of the aircraft from guns placed away from the targets itself. A steady vertical dive might help predicted fire.
     
  16. RCAFson

    RCAFson Well-Known Member

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    Theoretically, they should be. Apparently the dive brakes on the Barracuda were effective enough to keep the aircraft under the Vmax limit, but on the Sb2C, for example, increases in aircraft AUW meant that the DBs were no longer effective in keeping the speed under Vmax during a prolonged dive.
     
  17. stona

    stona Well-Known Member

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    A shallow dive is equally predictable. It also takes longer. There is a high probability of defensive fire coming from the target, though of course it may well come from other weapons within range.

    The biggest advantage of a vertical dive is an increase in accuracy. This was established originally by the Royal Flying Corps. After 'on the job' attempts during the war, the first recorded being by an S.E.5a of No.84 Squadron on 14th March 1918, extensive dive bombing tests were carried out by the British at Orfordness during 1918/19.

    The Germans went for a different ground attack system using armoured aircraft operating in 'Schlachtstaffeln'. The Germans did not dive bomb during WW1. The Ju K47 was developed for the ground attack role, though its inherent strength allowed it to be used for shallow bombing in 1927/8 and this has led to it being referred to as the grandfather of the Ju 87.

    The doctrinal origins of the German development of dive bombing are long and various. Here I will just say that the dive bomber faction's attitude is summed up nicely by a directive from General Kurt Freiherr von Hammerstein-Equord, in 1932 when he was Chief of the Army High Command (I think, haven't checked date). Air defence and air combat forces were to be considered solely as "auxiliary weapons of the army and navy."

    Cheers

    Steve
     
  18. pbehn

    pbehn Well-Known Member

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    Can someone explain how diving vertically on a target reduces the bombers vulnerability, I would have thought it was the opposite, just askin'.
     
  19. stona

    stona Well-Known Member

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    #19 stona, May 28, 2014
    Last edited: May 28, 2014
    It minimises area and time exposed to the target.
    The dive bomber is most exposed to fighter and artillery on approach (when the FAA fighters in the Med attempted to disrupt their formations and hence bombing accuracy for example) and, particularly to fighters, as they reassemble at low level following the attack.
    Steve
     
  20. Greyman

    Greyman Active Member

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    Not according to the Pilot's Notes ...
     
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