Dive vs Torpedo Bomber

[RCAFson]

I've been there as well. For a 1940s era aircraft it would have presented few problems - Especially with the big, flat, Ford Island in the middle of it. - Likewise been to Taranto - You wouldn't even class that as a harbour in the geographic sense at all, at least not where the Italian fleet was anchored - Just a big bay open to the Med. Gotta wonder in both cases why more extensive anti-torpedo nets were not in place. The Germans had only had possession of Trondheim for a few months but they still managed to put anti-torpedo nets in place to protect Scharnhorst and Hipper by June 1940. Also been to the Tirpitz museum at Kaafjord - Now that's a confined anchorage.

An advantage that FAA Torpedo-divebombers had was that they could use a divebomb attack profile while torpedo bombing, so they could attack targets even in confined waters, where there was at least a few hundred yards of open water in front of the target, as they could dive vertically with the torpedo to avoid the terrain.

 

[MikeMeech]

Hmmm... I didn't say just harbours, I didn't say shallow harbours, I said confined harbours - As in small, enclosed, where a torpedo bomber would not be able to get into position to release its payload. As far as dive-bombing at night - of course you could do it if there was a bright moon (the FAA planned a moonlight attack by Skuas on the Scharnhorst and Gneisenau at Brest,) - But you can hardly depend on having a bright moon in an encounter fleet action. Incidentally, there was a dive-bombing attack in the middle of the night -The Skua attack on the Scharnhorst at Trondheim was done at 2 am in the morning - but being June that far North it was still bright daylight.

Hi

Just after dawn on 6th April 1941 a Beaufort of No. 22 Sqn. flown by Flying Officer K Campbell and crew made a low level torpedo attack against the Gneisenau in the heavily defended Brest harbour, putting a 40 feet hole in the ships side. The aircraft was shot down and crew killed, Campbell being awarded the VC. Ironically the ship had just been moved out of dry dock due to an unexploded 250 lb SAP bomb being near by. I don't think Brest harbour was very big or deep.

Mike

 

[Admiral Beez]

My great grandfather once told me he carried two screwdrivers. One was clean, bright and useful. The other was ugly and had a chipped blade, but he was attached to it anyway.

I ride an old Suzuki. You must use JIS screwdrivers, even though the screws look like Phillips, as Phillips driver will strip JIS screws. But you can use JIS in Phillips. So, if you want to carry only one screwdriver for both your old Japanese motorcycle AND your everyday fastening, get JIS.

If you have a limited CAG size, a dive bomber that can also carry a torpedo is better than a torpedo bomber that cannot dive bomb. Look at wing wing carriers today, where CAGs are made up of a single fixed wing type.

 

[Shortround6]

If you have a limited CAG size, a dive bomber that can also carry a torpedo is better than a torpedo bomber that cannot dive bomb.

They had to wait until they got powerful enough engines to allow one plane to do both.
The TBD Devastator used a 422 sq ft wing, The Northrop BT-1 (which was modified into the SBD) used a 322 sq ft, both used the same engine.

I would also note that, torpedoes being expensive, the requirement that lead to the Avenger required the plane to land back aboard the Carrier still carrying the torpedo and do so with a stalling speed of 70mph. A reason for it's 490 sq ft wing.

Most torpedo bombers were expected to have similar strike radius as the dive bombers but were carrying a heavier payload, for the Americans it could be twice as much (or even four times as much).
SB2Cs didn't start really carrying torpedoes until they got 1900hp engines and a quick change torpedo mount.

 

[kitplane01]

The job of sinking enemy ships was not solely the Royal Navy's, it was a job eagerly embraced by the newly independent Royal Air Force. The large AP and SAP bombs specifically to sink ships were designed and built and almost all bomber specifications of the inter-war years included the ability to lift such ordnance. Interestingly RAF medium bombers were initially supposed to also carry aerial torpedoes, as in Specification P.13/36 which eventually and in a convoluted way resulted in the Lancaster's huge and unobstructed bomb bay. The British wanted a multi-role aircraft (we are always short of money) and the new medium bomber to that specification was intended to form the backbone of the RAF's 'Striking Force', meeting requirements for General Reconnaissance, General Purpose AND Torpedo Bomber classes.
Enemy fleets were not operating in the vast expanses of the Pacific Ocean in British pre-war planning. The Western Air Plans all included some version of attacks on German warships and their harbours and these were indeed some of the first targets attempted by the RAF when war broke out.

As far as the RAF was concerned there was an inbuilt doctrinal opposition for anything that looked like close air support for the Army and dive bombing definitely fell under this umbrella. This was best summed up by Liddell-Hart in 1940 when he wrote in his diary that the RAF had "no suitable machines for low flying attack, and the Air Staff object to the idea of air counter-attack against troops moving up".

That left dive-bombing to the Royal Navy. The problem here is that the RN had long considered the best use of naval aviation was to carry torpedoes. What attracted the attention of torpedo advocates was the possibility of the aeroplane's use from the decks of ships. If torpedo aircraft could be carried in this way then attacks on the enemy's capital ships could be carried out with a combination of Fleet attack and air action. The most prominent apostle of this concept was one of the most influential men in the RN, Commander in Chief of the Grand Fleet, Admiral Sir David Beatty. Indeed, in August 1917 he, together with Captain (later Admiral Sir) Herbert Richmond developed a plan for exactly such a mass attack on the German fleet at Wilhelmshaven, involving no less than 120 torpedo carrying aircraft, each flight of 40 protected by 5 Sopwith fighters. The plan was nixed by Jellicoe and the Naval Staff, but it was decades ahead of its time, it was the Italians who would suffer a version of it at Taranto in 1940. The torpedo lobby was strong, in October 1918 the RN received its first purpose built torpedo aircraft (the Sopwith Cuckoo) and the first flush-decked aircraft carrier, HMS Argus, entered service in the same month.

This does not mean that the RNAS simply gave up on bombing. Between March and November 1915 No. 3 Wing RNAS in the Dardanelles made more than 70 bombing attacks on enemy warships. The results were not outstanding, though at least one vessel was sunk. There were other successes, in 1917 an RNAS bomber distinguished itself by being the first to launch a successful attack on the German warships Goeben and Breslau in the Mediterranean, both were damaged. Damaged is the key word. There was a general perception in the RN that in the case of larger vessels, torpedoes sank them, bombs damaged them, and the RN wanted to sink them.

Again, to cut a long story short, after 1918 the employment of torpedo aircraft was left entirely in the carrier fleet and it was in relation to fleet requirements that the torpedo operations subsequently developed. It was no longer seen as a truly offensive weapon (as in the Dardanelles or Beatty's ambitious plan) but as a means of assisting the main fleet. Any offensive operations would be undertaken by the main bomber force and that meant the RAF, not the RN. It was the RAF who would bomb the enemy's dockyards and heavy industry which supplied and sustained the German Navy. This was the essence of the RAF's offensive doctrine. There was no place in the RAF for torpedo aircraft, and little place in the RN for bombers.

Finally, there was the issue of who controlled the development and supply of aircraft. While the Air Ministry did concede that there was a place for torpedo aircraft within Fleet action, it had no interest in their development. As the RAF was responsible for providing aircraft to the Navy fleet requirements were never fully satisfied. The tensions between the two services are beyond the scope of this reply. Lessons learnt by the RNAS were forgotten by the RAF and only re-learned at considerable cost by the FAA and Coastal Command. As if this were not bad enough, the parlous state of British maritime aviation when WW2 started was a reflection of its neglect.

I'm not sure what the conclusion is (or if it was just a nice history lesson).

It could very reasonably be that torpedos were a better choice in 1920, even if dive bombers were the better choice in 1940.

In fact, the Swordfish could and did do both. I understand that they were more often torpedo bombers, but that might be FAA making their best decision given limited information, or it might be that the Swordfish isn't the world's best dive bomber and that was the airplane they had.

 

[kitplane01]

They had to wait until they got powerful enough engines to allow one plane to do both.
The TBD Devastator used a 422 sq ft wing, The Northrop BT-1 (which was modified into the SBD) used a 322 sq ft, both used the same engine.

I would also note that, torpedoes being expensive, the requirement that lead to the Avenger required the plane to land back aboard the Carrier still carrying the torpedo and do so with a stalling speed of 70mph. A reason for it's 490 sq ft wing.

Most torpedo bombers were expected to have similar strike radius as the dive bombers but were carrying a heavier payload, for the Americans it could be twice as much (or even four times as much).
SB2Cs didn't start really carrying torpedoes until they got 1900hp engines and a quick change torpedo mount.

This makes ZERO sense to me.

Torpedo bombers existed throughout the war. Given one had a torpedo bomber capable of meeting torpedo bomber requirements, one could put dive brakes on it, bombs in it, and have a dive bomber.

(or just use a biplane with wire braced wings, and not worry about speed brakes

 

[RCAFson]

This makes ZERO sense to me.

Torpedo bombers existed throughout the war. Given one had a torpedo bomber capable of meeting torpedo bomber requirements, one could put dive brakes on it, bombs in it, and have a dive bomber.

(or just use a biplane with wire braced wings, and not worry about speed brakes

The airframe has to be stressed for divebombing, and that always adds considerable weight. The FAA used biplane torpedo-divebombers because they had the wing area for STOL whilst lifting large loads with low powered engines, but the airframe still had to have the strength to fly a dive-bomber attack profile.

The TBF/TBM was only stressed for ~3g at max TO weight where the SBD and SB2C were stressed for ~7G.

 

[kitplane01]

The airframe has to be stressed for divebombing, and that always adds considerable weight. The FAA used biplane torpedo-divebombers because they had the wing area for STOL whilst lifting large loads with low powered engines, but the airframe still had to have the strength to fly a dive-bomber attack profile.

The TBF/TBM was only stressed for ~3g at max TO weight where the SBD and SB2C were stressed for ~7G.

That does make more sense.

 

[stona]

I'm not sure what the conclusion is (or if it was just a nice history lesson).

It could very reasonably be that torpedos were a better choice in 1920, even if dive bombers were the better choice in 1940.

In fact, the Swordfish could and did do both. I understand that they were more often torpedo bombers, but that might be FAA making their best decision given limited information, or it might be that the Swordfish isn't the world's best dive bomber and that was the airplane they had.

That the Air Ministry/RAF was not interested in torpedo aircraft. I made another reply further down. The raison d'etre of the RAF as an independent air force in the inter-war years was as a strategic bombing force and deterrent. Attacking ships with torpedoes was considered 'unsuitable employment' for aircraft.

It's why Coastal Command's striking force in 1939 and early 1940 consisted of two squadrons of these (though just 12 aircraft, less than one squadron, were operational at the outbreak of the war as the remaining aircraft were being overhauled).

The Vickers Vildebeest. It was not even originally specified as a torpedo aircraft but built to a 1926 specification for a 'light' bomber, which explains its exceedingly limited range.

 

[XBe02Drvr]

They had to wait until they got powerful enough engines to allow one plane to do both.
The TBD Devastator used a 422 sq ft wing, The Northrop BT-1 (which was modified into the SBD) used a 322 sq ft, both used the same engine.

This makes ZERO sense to me.

In order to lift the heavy torpedo, and to fly safely(?) at torpedo launch speeds on the same HP, the TBD had to (as Shortround said) have a much larger AND THICKER wing making it slower and more vulnerable when in harm's way. And due to its G limits, it couldn't maneuver as aggressively in its own defense, even when unladen. Their fuel efficient cruise speed was so much lower than other strike aircraft, that ideally they would be launched first if part of a combined strike and be overtaken enroute by the rest.
Cheers,
Wes

 

[Shortround6]

Designing and effective dive bomber wasn't quite as easy as it seems. The aircraft is the delivery system, the actual weapon is the bomb or torpedo (or bullets/shells).

I don't have information about the early US AP bombs but the 1000lb MK 33 that was introduced in october of 1942 was rated at piercing 5 in of deck armor if dropped from 10,000ft OR from 6,500ft in a 300kt 60 degree dive.

The slower the dive the higher the release point has to be to get the same armor penetration. The higher the release point the less accuracy and the more time for the ship to evade.

Ships with thinner decks can be attacked from lower altitudes and HE bombs don't need/use the impact speed for target effect. SAP bombs do need a certain impact velocity to penetrate light armor.

A lot of planes could "dive bomb" but if you are planning on attacking large ships with thick decks using a Biplane even with an AP bomb may not be the way to go.

Not to mention low, slow aircraft are an AA gunners dream.

 

[Dinger]

Hi

Just after dawn on 6th April 1941 a Beaufort of No. 22 Sqn. flown by Flying Officer K Campbell and crew made a low level torpedo attack against the Gneisenau in the heavily defended Brest harbour, putting a 40 feet hole in the ships side. The aircraft was shot down and crew killed, Campbell being awarded the VC. Ironically the ship had just been moved out of dry dock due to an unexploded 250 lb SAP bomb being near by. I don't think Brest harbour was very big or deep.

Mike

The "Roadsteads" of Brest Harbour are huge - The harbour where the Gneisenau was is only separated from it by a low mole - Hence it presented no problem for the run-in of the Beaufort and could not be deemed "confined". - Where Campbell and his crew were amazingly brave was that that mole was lined with AA guns. There is a nice map on this website...

Coastal Command Bombers Against the German Navy II

 

[Reluctant Poster]

Redundant post

 

[Reluctant Poster]

Designing and effective dive bomber wasn't quite as easy as it seems. The aircraft is the delivery system, the actual weapon is the bomb or torpedo (or bullets/shells).

I don't have information about the early US AP bombs but the 1000lb MK 33 that was introduced in october of 1942 was rated at piercing 5 in of deck armor if dropped from 10,000ft OR from 6,500ft in a 300kt 60 degree dive.

The slower the dive the higher the release point has to be to get the same armor penetration. The higher the release point the less accuracy and the more time for the ship to evade.

Ships with thinner decks can be attacked from lower altitudes and HE bombs don't need/use the impact speed for target effect. SAP bombs do need a certain impact velocity to penetrate light armor.

A lot of planes could "dive bomb" but if you are planning on attacking large ships with thick decks using a Biplane even with an AP bomb may not be the way to go.

Not to mention low, slow aircraft are an AA gunners dream.

The Mk 33 and Mk 1 (1600 lb) AP bombs did not work as advertised and were a major disappointment to the USN BuOrd which designed and manufactured them. The much improved Mark 13 torpedo of 1944 became the preferred weapon for attacking armored ships. I have noted in a previous post that the RN used the Mk 1 to attack the Tirpitz without success. From the

As for the early war AP bombs, primitive is the best way to describe them. They were pre WWI technology as can be seen by the "pillbox" armor piecing cap on the M61

The M61 was converted from a projectile for a deck piercing mortar first produced in 1890. Here is a mesmerizing video of a battery of these mortars in operation.

 

[Shortround6]

The bombs may not have worked as advertised, but they do point out the need for different airplanes in the 30s and early war years, A torpedo bomber with dive brakes added on was unlikely to dive fast enough or pull out late enough to actually be a good dive bomber even if it could dive steeply or had clearance to drop a bomb in a 60 degree or better dive.

There were a number of requirements for aircraft that seldom make into the short stories or articles about them that had quite a bit to do with the actual design choices. Landing speeds and take-off runs and desired ranges had quite an impact.

 

[RCAFson]

The bombs may not have worked as advertised, but they do point out the need for different airplanes in the 30s and early war years, A torpedo bomber with dive brakes added on was unlikely to dive fast enough or pull out late enough to actually be a good dive bomber even if it could dive steeply or had clearance to drop a bomb in a 60 degree or better dive.

There were a number of requirements for aircraft that seldom make into the short stories or articles about them that had quite a bit to do with the actual design choices. Landing speeds and take-off runs and desired ranges had quite an impact.

Dive brakes limited the speeds of most divebombers up to the SBD-3 (including the Albacore) to between 200 and ~250 knots. A divebomber achieving 300 knots in a low altitude release would be exceptional, IIRC.

The Barracudas attacking Tirpitz released their 1600lb bombs at up to 65degs

 

[stona]

Dive brakes limited the speeds of most divebombers up to the SBD-3 (including the Albacore) to between 200 and ~250 knots. A divebomber achieving 300 knots in a low altitude release would be exceptional, IIRC.

The Ju 87 was certified to carry out dives up to 'stress group 5' which required a maximum safe diving speed of 600 Km/h (about 373mph). The dive brakes were required to slow the aircraft down to give the pilot time to properly aim at his target and to reduce the forces during the pull out.
I have no idea what the maximum safe dive speeds were for Allied types, but I doubt they were anything like that.

 

[swampyankee]

The Ju 87 was certified to carry out dives up to 'stress group 5' which required a maximum safe diving speed of 600 Km/h (about 373mph). The dive brakes were required to slow the aircraft down to give the pilot time to properly aim at his target and to reduce the forces during the pull out.
I have no idea what the maximum safe dive speeds were for Allied types, but I doubt they were anything like that.

This site, Pearl Harbor Douglas SBD Dauntless Scout / Dive Bomber shows the nominal attack profile of an SBD; doing a little math gives a speed of 300 mph during the pullout. I remember seeing that the SBD was stressed for at least 7 g; nominally, this would permit about 400 mph. See also How fast do dive bombers dive?

Note that there is another limit, never-exceed speed, Vne, which can be set by flutter or other constraints, not g limits.

 

[Glider]

The "Roadsteads" of Brest Harbour are huge - The harbour where the Gneisenau was is only separated from it by a low mole - Hence it presented no problem for the run-in of the Beaufort and could not be deemed "confined". - Where Campbell and his crew were amazingly brave was that that mole was lined with AA guns. There is a nice map on this website...

Coastal Command Bombers Against the German Navy II

I have seen a photo of the Beaufort wreckage being lifted out of the harbour. What was striking was the body of the pilot was still upright in his seat, looking almost untouched, it was very clear as the impact on the water had stripped away the nose of the aircraft. It's one of those pictures that you never forget.

 

[Dinger]

To have kept on going when the rest of the other attacking aircraft had all turned back because of the lousy weather was amazing bravery.