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Were torpedo bombers intentionally slow?

Discussion in 'Aircraft' started by DerGiLLster, Jun 10, 2016.

  1. DerGiLLster

    DerGiLLster Member

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    Okay I do not know much about torpedo bombers during the second world war. I know a few types being the British Fairey Swordfish which delivered the paralyzing hit to the Bismarck and the American SBD destroyer which played a role in midway. What I want to ask is this, were torpedo bombers intentionally slow?

    I understand that slow aircraft were good in the dive bomber/ground attack role since when going in at a angle they need to sight their target, but was it necessary for a torpedo bomber? Slower speed can a play a role in stabilizing the aircraft but was it possible for there to be a land based aircraft that could go at fast speeds and delivers aerial torpedoes to ships?

    Wouldn't launching an aerial torpedo really be no harder from a fast aircraft than that of a slow aircraft since the ship is in sight and is a still target for a plane flying toward it? Would a fast aircraft be at an advantage since it could launch the torpedo and escape with a lower chance of it being shot down or would the faster speed lower the accuracy of the aerial torpedo?
     
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  2. belasar

    belasar Court Jester Staff Member

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    First off the SBD was a divebomber, not a torpedo bomber.

    Second torpedo's are big hulking things and with most aircraft they carried them slung outside the plane adding to the overall drag of the aircraft.

    Some aircraft capable of carrying torpedo's were relatively speedy, but to effectively launch their fish they had to approach their targets at a certain speed to ensure a proper hit.
     
  3. Rantalith

    Rantalith Member

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    I think that they were slow due mainly to the early torpedoes exploding if released above a speed of 130 mph or so. This is the USA one since I think I remember the Japanese one being able to be released at around 150 mph or so.

    The prevailing thought was that the airplane would get close and drop in perfect conditions that the plane did not need to go any faster than needed to release the torpedo.

    As already pointed out, the torpedo was a huge thing and was carried externally under the plane. Later in WW II the torpedoes improved and I think they could be released at higher speeds.
     
  4. RichTO90

    RichTO90 Well-Known Member

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    No, as mentioned the SBD was a dive bomber. You are thinking of the TBD. For the US see http://www.ww2f.com/topic/58329-fighters-at-midway/?p=653963


    No, it wasn't a good thing for torpedo bombers to fly low and slow. As I have pointed out before, with a few more minutes notice, the Japanese VT strike on Battleship Row on 7 December would have been a disaster - for the Japanese. 29 aircraft attacked in an almost continuous stream and the ninth one in was hit by Bagley's ready gun, just eight to ten minutes into the attack, as were virtually all those that followed, while five of the last seven were shot down.

    As mentioned above, improved torpedo design eventually resulted in high-altitude, high-speed drops, but by then missiles were coming more into favor.
     
  5. DerGiLLster

    DerGiLLster Member

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    Oops, thank you for the correction.
     
  6. Sheldrake

    Sheldrake Member

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    The short answer is: not necessarily. WW2 torpedoes needed to be dropped from a low altitude in level flight below a critical ground speed. Not only did they torpedo need to enter the sea without breaking up, but these unguided weapons needed to be launched accurately. Whatever the torpedo bomber, the torpedo needed to be launched from C 50-150 ft at C 100-150 kts

    Most nations used variants of their standard medium bombers as land based torpedo bombers. The British had the Bristol Beaufort and Vickers Wellington, The Japanese naval bombers G3M and G4M, the Germans used the Ju88 and He 111 and the Italian s used the SM79. The British used twin engine fighters such as the Bristol Beaufighter was also a very effective torpedo bomber. If the USAAF had wanted to, they could have dropped torpedeos from the B25 or B26.

    Torpedo bombing is a very risky and expensive activity. It was the aircrew role with the highest fatalities in the RAF. Somewhere around 80% of aircrew died. It was safer to be ion heavy bombers over Germany. Slow and low and in sight of the enemy is a dangerous place.

    Aircraft designs are a compromise, with the engine available imposing a limit on weight and performance. A naval strike aircraft needed fuel, for range, a second or even third crewman help navigate and man defensive weapons, and strengthened undercarriage for carrier landings. The engines available in late 1930s resulted in slow and low aircraft such as the British Fairy Swordfish,Japanese B7N (Kate) and US TBD (Devastator).

    More powerful engines resulted in aircraft such as the US Grumman TBF,Avenger, the British Fairy Barracuda and Japanese Nakajima B6N which had substantially higher performance. By 1944 the British had ordered 100 Mosquito TR33 as a twin engine carrier borne naval torpedo bomber.
     
  7. lwd

    lwd Ace

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  8. Carronade

    Carronade Ace Patron  

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    "slow" is a relative term; the TBD was a high performance, state-of-the-art aircraft when it entered service, but the steady progress of aircraft design and engine power made it obsolescent by the time it saw combat. The process of replacing it with the faster, more powerful TBF was underway, but the battle of Midway came along at just the wrong time.
     
  9. R Leonard

    R Leonard Member

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    To quote an USN aviator of my acquaintance who flew combat at Midway: “Torpedo plane pilots and crews had the most self-sacrificing mission in US naval aviation, not just there (Midway) but through the entire war.”

    The early Mark 13 was a seriously flawed weapon . . . if your targets of choice could easily exceed 30 knots. All one has to do is turn the ship with stern towards the torpedo and then out run it. Yamato did this at Leyte. For the Americans, a good deal because Yamato turning away from torpedoes turned away from the action. None the less, Yamato did out run the torpedoes - - - this time. Her sister ship did not do as well in the confined waters of the San Bernardino and was sunk. Yamato did not do so well about 6 month later when swarmed from all directions . . . there was no turning away from an all compass point attack. On the other hand, against 10 to 15 knot merchies and naval auxiliaries, the Mark 13 did just fine.

    USN torpedo planes, especially in the first half of the war before some redesigning mitigated some of the problems, were limited by the performance factors of the Mark 13 torpedo. In many ways the attack executed by a torpedo squadron faced the same problem as that of a submarine. One could not come just come up on the broadside of a moving ship and let fly. The problem is one of putting the torpedo in the water aiming for a place one hopes the target will be base on where it is when the torpedo is dropped – this is called, the technical term, deflection, the not so technical term, lead.

    Dropping the torpedo, taking into account the distance the torpedo has to travel before the warhead arms, about 800 yards, and aiming to where the ship is now, does you no good. With a torpedo such as the Mark 13, with a 33.5 knot maximum speed, means the drop is made about 1000 yards from the target. At a straight ahead run at a stationary target, that means the torpedo will run for about target about a minute before striking the target.

    Of course that presumes the torpedo doesn’t porpoise, sink, veer of course, premature from a surface run, or any other of a long list (sometimes combinations) of things that can go wrong.

    Consider, then, the same 1000 yard range drop against a ship, say a light cruiser, maneuvering at combat speed on a course 90 degrees to the torpedo plane’s approach. The torpedo pilot, clever fellow, recognizes that the target is moving and aims for the bow. Unfortunately, that still will not be good enough. A light cruiser, say of the Nagara class, had a top speed of 36 knots. In a combat situation you can be sure that the captain is calling the engine room commanding “more, more, more!” But, vagaries of bottom fouling and wear and tear on the engine, let’s figure the best he’s going to get is about 35 knots. Note that his speed is already 1.5 knots faster than the torpedo’s maximum speed. The 35 knots also means that the by the time a minute passes from the time the torpedo was dropped, the bow of the ship has already moved some 3450 feet; that is about 6 ship lengths.

    Thus, just aiming for the ship’s bow at time of release will result in a clean miss by about 2800 feet.

    Folks in the torpedo business, aircraft and submarines, were well aware of the problem. Submarines, of course can not only shift their aiming point, but can also crank in a gyro adjustment to the torpedo itself to make it run at an angle to the ship’s track. With torpedo planes, nifty aiming devices, originally mechanical, later electronic, allowed the pilot to correct his angle of approach in order to add in the necessary deflection to have the torpedo reach a point way out in front of the ship at the same time that some piece of the ship is likely to be at the same spot. But to do so he was required to point his aircraft towards that imaginary point.

    This, of course, enters more variables into the problem. Now shooting some where out along the ship’s track means a longer torpedo run, on our case, presuming nice straight lines, now the torpedo has to run about 4 minutes to reach a spot some, now 4000 yards, down range from that first drop point mentioned above. Not too bad, the Mk 13 had a range of about 6200 yards so you’re still within the weapon’s operating parameters.

    But, this really is not very good idea; the longer a torpedo is in the water, the more that can go wrong, and, especially, the longer yon ship captain has to react to the situation

    . . . you are now hopefully now picturing a three dimensional problem in your head.

    One way to shorten the time in the water is to actually fly down the bearing you want the torpedo to take. Well, that means turning to a slightly intersecting course with the cruiser’s course . . . certainly a problem because now the plane is effectively broadside to the cruiser and subject to the tender attentions of its antiaircraft suite. The problems just keep mounting. This grave situation exists as the plane, as of necessity for targeting purposes, passes ahead of the ship . . . remember, the plane is traveling at least 3 times the speed of the ship. And by this time, the cruiser’s captain, no idiot and certainly knowledgeable himself about torpedo targeting, says to himself, “Ah ha, this clown is going to make a drop somewhere where he thinks I’m going to be,” and promptly executes a 90 degree turn, spoiling the whole plan.

    Frankly, one really has to catch someone with his pants down to execute a successful single plane attack on a moving warship. Merchants and naval auxiliaries might be a little easier, they are certainly slower.

    This is why torpedo squadrons are divided up into divisions and sections. In USN VT doctrine, torpedo attacks against capital warships usually dedicated at least half, and for really worthwhile targets like battleships and carriers, an entire squadron to a single attack. Why so many? Well, for starts, we already know that at least half the torpedoes dropped will suffer some malfunction . . . that is a given . . . so a 12 plane squadron would expect only 6 torpedoes to run “true.” And what of the above question as to the danger of collision? Well there’s always a danger of collision, but remember that this sort of formation flying and tactical formations and actions are routinely practiced, over and over. No, there was no particular danger of collision. Torpedo attacks by a trained squadron were not willy-nilly affairs; everyone knew where they were supposed to be and how to maintain formation.

    Presume for a moment an attack on an opposing carrier. Forgetting for the moment about escorts and defending CAP and other clever impediments to a torpedo attack, here is a carrier pounding along at about 33 knots, just slightly less than the top speed of the torpedo. - - remember those terrible word problems? If a car leaves city A bound for city B at T1 time and S1 speed how long does it take a car leaving at T2 time and traveling at S1+X speed to catch up? - - same deal here. Half a knot does not buy much in overtake capability. This means that one has a choice. Launch aiming for some point out in front of the ship while moving somewhat parallel and, maybe, slightly ahead of the ship OR approach from the carrier’s bow and launch for a much shorter run where the torpedo approaching from the front intersects the ship’s course.

    Of course, all by itself, the carrier captain is going to see you and take evasive action. This is where the multiple plane attack enters the picture. The navies operating torpedo planes all had the same solution to the high speed targeting approach.

    The basic attack was the “Anvil.” In this attack method, executed ideally either from a bow on approach or a stern following approach, half of the attacking planes approach on the port side of the target and half to starboard.

    With the stern attack, the attacking element approaches on both sides from abaft the beam of the carrier, bracketing, and when abeam, or, better, slightly drop torpedoes slightly angled to intersect carrier’s track. (Remember, you want to minimize the time your torpedoes are in the water, both in terms of reaction time and the device’s range, so with the stern approach the abeam position would be, of necessity, pretty close to the target, like in the neighborhood of 500 yards . . . spitting distance for a 12.7 mm machine gun mounted amidships.)

    From a bow on approach, attacking elements approach in the opposite direction from the carrier’s track closing on both sides of the bow. This is a somewhat safer approach as fewer defending antiaircraft batteries can be brought to bear. The approach does require some delicate timing as the elements must ensure that the dropped torpedoes will travel a sufficient distance to arm the warheads. At the appropriate point, though, the element drops the torpedoes, again angled towards the carrier’s track and taking into account the ship’s speed and then breaks away, thus avoiding the ship’s broadside batteries.

    In both of these methods, the object is to have a spread of torpedoes approaching the carrier’s track, to intersect at a point of impact based on the ship’s speed. The happy part is that the multiple torpedoes presents a problem very hard to solve with ship handling, a turn to either side puts the ship in danger of running into a torpedo and to keep going straight leaves the same danger.

    This is the classic torpedo plane attack method. It requires six to twelve planes and, now taking into account escorts and CAPs, is very hard to execute. Just getting into position can be extremely hazardous.

    Take for example the 12 planes from VT-3 at Midway. Closing from astern on the maneuvering Hiryu, LT Pat Hart, the executive officer, led half the squadron in an arcing track to the left so as to come up on the ship’s port beam. They never made it, all were shot down by CAP and AA fire. The squadron commander, LCDR Lance Massey, led his two divisions from the abaft position to close on the starboard beam. Four of the six were shot down, including Massey, and the other two were forced to make their drops early and break away. No hits scored and the two surviving planes were forced to ditch from damage as they returned to the vicinity of the US carriers. Two pilots and one of the two rear gunners survived. The famous attack by VT-8 was even worse, they never deployed for an anvil attack but were picked off one by one in a straight in stepped line astern formation.
     
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  10. mcoffee

    mcoffee Son-of-a-Gun(ner)

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    The only thing you could add to that is "class dismissed".
     
  11. R Leonard

    R Leonard Member

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    Unless you want a gazillion pages on relative survivability of VT vs VB types, but that's another subject entirely.
    :)
     
  12. EagleSquadron12

    EagleSquadron12 New Member

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    If you've ever seen a TBF Avenger in person you would know why that thing is slow...it's fricking massive for a carrier based plane...not to mention the torpedoes are heavy and increase the overall drag on the airframe
     
  13. CAC

    CAC Ace of Spades

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    The biggest difference (IMO) is that the torpedo plane had to handle at low speeds...a purpose built aircraft would have a low stall speed, enabling a reduction in speed without a reduction in lift. This was usually achieved by the shape and size of the wing...this wing was a slow speed wing, not designed for high speed.
     
  14. Poppy

    Poppy grasshopper

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    Might add the 'String Bag'- Fairey Swordfish was a biplane, and did pretty well. Especially at Taranto, where its low speed had the defenses shooting way ahead of the unexpectedly slow craft. Then its' maneuverability got it out of harms way after release.
    Remarkable airplane, credit to the Men who flew her.
    https://en.wikipedia.org/wiki/Fairey_Swordfish
     
  15. phylo_roadking

    phylo_roadking Member

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    Other considerations....

    Sometimes two, but mostly THREE crew, their equipment and flying positions. Three bodies, flying kit, oxygen etc. is a lot of "people weight"...

    Often defensive armament to "ensure" they reached their targets - as above, ditto the weight of one or more pintle or turret-mounted MGS and all their ammo; brass weighs quite a lot...

    Except for the Fairey Swordfish - quite a lot of armour protecting that crew - as torpedo bombers could ALSO be re-missioned as level bombers...and in the case of the Stringbag most often was.

    As noted above in the thread, extra range required over land-based aircraft...which meant extra fuel....LOTS of it - enough to GET all the above-mentioned weight to where it was going ;)

    But finally....and most of all... torpedo bombers in the majority of the war years DID attack their targets low and straight as part of their targeting regime; they were attempting to set their torpedos on track to intercept the target further along the target's OWN track when the torpedo was launched - and a straight-flying slow aircraft optimised the chance of a torpedo hitting the water, bottoming out, and rising to its set running depth without being knocked off track...

    Especially when attacking major surface units and capital ships - where the torpedo bonbers were trying to hit quite small PARTS of the target vessel! Towards the bows, where the armour belt was thinnest or had already terminated - and ditto towards the stern of the vessel...where a hit on vulnerable rudders and steering chains, prop shafts etc. could drastically reduce the target's speed - or halt it dead in the water.
     
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