Feasibility of interwar 2,000 lb. armed FAA dive bomber

[Admiral Beez]

Not looking for an improved Skua, but instead a clean sheet design. Given the engine and other limitations of the time, was it feasible to make a >200 mph (loaded), folding-wing (need to fit Ark Royal’s 22 ft lift), steep angle divebomber armed with 2,000 lbs. of bombs (1,000 lb centreline, 500 lb underwing) to enter FAA / RN aircraft carrier service by summer 1939? For starters we’d need to develop a 1,000 lb. armour piercing bomb, as the RAF and FAA do not have one.

I‘m not sure Bristol can help, how about two Merlins on one shaft like on the Bolkhovitinov Spark?

Though the pilot‘s view for landing will be hilariously terrible, so maybe not! 😧 It might also rip apart when recovering from a near 90 degree dive.

Anyway, can we get the FAA a 200+ mph, 2,000 lb armed ship killer for 1939?

 

[Howard Gibson]

Not looking for an improved Skua, but instead a clean sheet design. Given the engine and other limitations of the time, was it feasible to make a >200 mph (loaded), folding-wing (need to fit Ark Royal’s 22 ft lift), steep angle divebomber armed with 2,000 lbs. of bombs (1,000 lb centreline, 500 lb underwing) to enter FAA / RN aircraft carrier service by summer 1939? For starters we’d need to develop a 1,000 lb. armour piercing bomb, as the RAF and FAA do not have one.

I‘m not sure Bristol can help, how about two Merlins on one shaft like on the Bolkhovitinov Spark?

View attachment 657088

Though the pilot‘s view for landing will be hilariously terrible, so maybe not! 😧 It might also rip apart when recovering from a near 90 degree dive.

View attachment 657089

Anyway, can we get the FAA a 200+ mph, 2,000 lb armed ship killer for 1939?

Did the FAA perceive that the Skua was a marginal aircraft? View over the nose is especially important on carrier based aircraft. The Bolkhovitinov Spark just looks like a bad idea.

How about a dive/torpedo bomber with a Bristol Hercules engine? The Hercules is in the ballpark of a Wright R-2600 in displacement. The problem with the Skua, the Roc, and the Barracuda is that they used small engines. The Hercules was much better.

At some point, people testing de Havilland Mosquitoes miscommunicated and they loaded 10,000lb into one of their aircraft. The Mosquito took off and flew and everything was fine. Mosquitoes were never sent into combat in that state. An unarmed Mosquito with 10,000lb of stuff on board would have been intercepted and shot down, however competently it flew otherwise. Maximum cargo and bomb loads are arbitrary, and all sorts of assumptions are made about what the aircraft will encounter. 2000lb was the nominal capacity of a Grumman TBF Avenger. A Hercules powered bomber operating of a coast occupied by the Luftwaffe would have to balance bomb load with survivability.

 

[Shortround6]

Anyway, can we get the FAA a 200+ mph, 2,000 lb armed ship killer for 1939?

how about two Merlins on one shaft

How about getting a single 1000lb bomb, of any type, onto the shipboard aircraft?
The Russians used a prop shaft, running through where the cannon would go, from the rear engine to the reduction gear and each engine drove a separate propeller.
The Merlin simply doesn't have that space between the cylinder banks. Short of designing new crankcases, reduction gears and supercharger section to hold standard (or close to it ) Merlin crankshaft and rods, etc and Merlin cylinder blocks (?) this won't work. But it doesn't need to.

Your best bet would be a Fulmar, leave 1/2 the guns out and about 3/4s of the ammo and you are 1/2 way to the 1000lb bomb from a 500lb bomb. But it is late.

I have pointed it out before. Stick a Pegasus engine on the Skua, you have a plane very close to an SBD.
Just make you have a good propeller.

In 1939 you are lucky to get about 1375-1390hp out of a Hercules engine.

 

[Admiral Beez]

How about a dive/torpedo bomber with a Bristol Hercules engine? The Hercules is in the ballpark of a Wright R-2600 in displacement. The problem with the Skua, the Roc, and the Barracuda is that they used small engines. The Hercules was much better.

I think we’re too early for the Hercules to have the aircraft in service before WW2. Though the Hercules engine was first run in 1936 so the pre-war aircraft could be “designed-for-but-not-with” the Hercules. Settle for a smaller engine until the Hercules is ready.

I‘d stay away from the dual role combo DB with torpedoes, instead we’re looking for an early British Val or SBD. No one is dive bombing with a Mosquito, but a CV-capable, folding wing twin DB could be doable. It will need to be narrow to fit down the 22ft wide lifts. But has there been any twin DB capable of near 90 degree dives like we’re looking for here?

 

[Shortround6]

Check to see if;

A, your catapults will handle a twin engine aircraft in 1939/40
B, your arresting gear will handle a 12,000lb aircraft in 1939/40
C, your elevators handle 14,000lb aircraft.

You have a lot more limitations that 22ft lifts.

 

[ThomasP]

re: 1000 lb AP bomb

If the (inter-war) Admiralty had asked for a 1000 lb AP bomb it would most likely have had a Ø12" with a L/D ratio of ~2.6. If the design/profile of the 450 lb AP was used it would end up weighing ~980 lbs with a charge weight of ~100 lb HE.

The Admiralty had previously ordered 450 lb (Ø9.2") and 1500 lb (Ø13.5") AP bombs to be developed. Development of the 450 lb being complete in 1927, and development of the 1500 lb finished in 1931. See: "Could the FAA have been better prepared for WW2?".

The 1500 lb AP was intended to be carried by any airframe capable of carrying a torpedo. Thus a Shark, Swordfish, or Albacore could have carried it. Of course, none of these aircraft were fitted with a bomb swing so they would not have been able to dive bomb in the near vertical with the 1500 lb. But there is no particular reason that a bomb swing could not have been fitted. The Shark and Swordfish were not really stressed for dive bombing, but the Albacore was. The Albacore was capable of carrying a 2000 lb bomb load (4x 500 lb, 2x under each wing) and could dive bomb at 60-70 angles - and occasionally did so when attacking shore/land targets (the flaps were intended for use as dive brakes).

So I think the answer to the question in the OP (ie [What is the] "Feasibility of interwar 2,000 lb. armed FAA dive bomber") is yea, verily. The only question in my mind is what would the dedicated airframe look like. If low speed TO and landing and all weather operations took precedence - then it would probable be a more compact Albacore or more rugged Swordfish. A biplane design would eliminate anything like a 200 mph top speed. Otherwise maybe something similar to the Fairey monoplane design that was entered for the Albacore specification?

Unfortunately, the only information I have been able to find is that the monoplane design weighed slightly less than the Albacore, TO and landing speed would both be significantly higher, and Vmax would be just over 200 mph clean - all with the same powerplant as fitted to the Albacore.

 

[tomo pauk]

Ju-87C copy powered by Merlin X?
TBD Devastator copy powered by Pegasus?
Albacore powered by Pegasus?

 

[Admiral Beez]

Ju-87C copy powered by Merlin X?
TBD Devastator copy powered by Pegasus?
Albacore powered by Pegasus?

Devastator is not a dive bomber. I did my best in the OP.

 

[don4331]

The French demonstrated how to build an AP on the fly - take a BB cannon round, remove the cannon fuse (needs high speed rotation to arm, you won't get that with bomb), with fuse removed empty explosive, weld on fins, replace explosive, install bomb fuse. If you want to get really fancy machine in mounting lug. RN has a number of 12" rounds kicking around from the Great War - that's a 850lb+ AP/SAP/HE bomb on short notice. You can special order the perfect round later.

But how many 1k lb AP bombs do you need? They aren't heavy enough to penetrate deck armour of Scharnhorst/Bismarck classes; they're overkill for anything else (They'd go through bottom before exploding).

Closest historical plane would have been Hawker Henley. Design was for 2-250lb bombs in bombay, 2-100lb on wings. That's with Merlin II and fabric covered wings. Upgrade the Merlin to the VIII (from Fulmar) on 100 octane (might need to increase cooling a smidge) and metal covering on wings. Modify bomb bay to hold single 12" ordinance (250lb would have been about 8"; I don't know if they were tandem or side by side), collapsible fins if bomb bay length is issue/bulge bomb bay door if required for larger diameter.

 

[tomo pauk]

Some more:
- navalized Fairey Battle with Pegasus (shaves 600+- lbs vs. Merlin installation)
- same with Henley
- copy of Fi 167, Merlin X in the nose

 

[Ovod]

The French demonstrated how to build an AP on the fly - take a BB cannon round, remove the cannon fuse (needs high speed rotation to arm, you won't get that with bomb), with fuse removed empty explosive, weld on fins, replace explosive, install bomb fuse. If you want to get really fancy machine in mounting lug. RN has a number of 12" rounds kicking around from the Great War - that's a 850lb+ AP/SAP/HE bomb on short notice. You can special order the perfect round later.

But how many 1k lb AP bombs do you need? They aren't heavy enough to penetrate deck armour of Scharnhorst/Bismarck classes; they're overkill for anything else (They'd go through bottom before exploding).

Closest historical plane would have been Hawker Henley. Design was for 2-250lb bombs in bombay, 2-100lb on wings. That's with Merlin II and fabric covered wings. Upgrade the Merlin to the VIII (from Fulmar) on 100 octane (might need to increase cooling a smidge) and metal covering on wings. Modify bomb bay to hold single 12" ordinance (250lb would have been about 8"; I don't know if they were tandem or side by side), collapsible fins if bomb bay length is issue/bulge bomb bay door if required for larger diameter.

The AP bombs used by the Imperial Japanese Navy during the attack on Pearl Harbor in 1941, which sank the USS Arizona among others, were developed from discarded artillery sells, 14 inch calibre if I recall. I think they were in the 800 kg weight class (1,700 lb.).

 

[Admiral Beez]

The AP bombs used by the Imperial Japanese Navy during the attack on Pearl Harbor in 1941, which sank the USS Arizona among others, were developed from discarded artillery sells, 14 inch calibre if I recall. I think they were in the 800 kg weight class (1,700 lb.).

I wonder what happened to the stockpiles of 12” and 13.5” shells from the RN dreadnoughts and predreadnoughts scrapped in the 1920s?

 

[Ovod]

I wonder what happened to the stockpiles of 12” and 13.5” shells from the RN dreadnoughts and predreadnoughts scrapped in the 1920s?

Don't know. But unwanted munitions often ended up dumped in piles at the bottom of the North Sea or Irish Sea. The RN would only have needed to retain a small proportion of the AP version of these shells to create a stockpile of aerial AP bombs.

 

[EwenS]

Some must have been retained as there were 54 spare 13.5” barrels and 6 turrets stored at Rosyth in 1939 as well as the turrets still on Iron Duke. 3 were used in railway mounts around Dover in WW2.

 

[Shortround6]

It takes a bit more work than outlined above.

Some of the shells have different shaped noses and/or ballistic caps.
Since the shells are not spinning, or not spinning very fast, even with fins you need to make sure you have the desired stability.

AP shells often had an explosive weight of around 2%.
Since the AP bomb no longer has to rotate at high speed and be subjected to tens of thousands of PSI chamber pressure when firing and Since the deck armor is thinner the shells have nowhere near the stress put on them compared to punching through thicker armor.

A lot of the converted battleship shells were bored out with thinner walls so they would hold more explosive.
This also meant they were lighter than the parent Battleship shells.
In some cases the ballistic caps/windshield were removed.

 

[ThomasP]

The 2000 lb load is the main problem (I think).

The Bristol Pegasus (as Shortround6 mentioned above) was rated at 900-1000 BHP for TO in its latest Marks at the start of the war. The US was able to develop the SBC Helldiver biplane and SBD Dauntless monoplane in the same timeframe, both using engines in the 900-1000 BHP for TO range and both capable of carrying a 1000 lb bomb at over 200 mph. I do not see why the British could not do the same if building to a similar concept. However, a 2000 lb bomb load was never in the cards for the SBC as it was too small, and only possible for the SBD when fitted with more powerful engines. The fuel load was reduced drastically in the SBD-1 thru -5 when maxed out on bomb load (1x1000 lb + 2x 250 lb or 1x 1600 lb) - the joke was that you could not launch until you could see the island form the carrier bridge. The late-war SBD-5 and -6 were the only variants that had a normal range with normal fuel and full bomb load, but they had an engine rated at 1350 BHP for TO.

 

[tomo pauk]

The Bristol Pegasus (as Shortround6 mentioned above) was rated at 900-1000 BHP for TO in its latest Marks at the start of the war. The US was able to develop the SBC Helldiver biplane and SBD Dauntless monoplane in the same timeframe, both using engines in the 900-1000 BHP for TO range and both capable of carrying a 1000 lb bomb at over 200 mph.

In 1938, Pegasus was rated at 980-1010 HP (87 oct fuel).
Ju-87R (1000 HP for take off with Jumo 211A) was erstwhile rated for a 1100 lb bomb + two drop tanks, and in 1940, on same power, was rated for a 2200 lb bomb + two drop tanks. Yes, it was not a navalized bomber.
Douglas TBD carried a 2200 lb torpedo with 900 HP low-level rated R-1830.

Trick was to have a big wing area, with good flaps if possible. TBD's wing area was in the ballpark of what Bf 110, Me 410 or Pe-2 had.

 

[elbmc1969]

In 1938, Pegasus was rated at 980-1010 HP (87 oct fuel).
Ju-87R (1000 HP for take off with Jumo 211A) was erstwhile rated for a 1100 lb bomb + two drop tanks, and in 1940, on same power, was rated for a 2200 lb bomb + two drop tanks. Yes, it was not a navalized bomber.
Douglas TBD carried a 2200 lb torpedo with 900 HP low-level rated R-1830.

The Stuka is by far the better example. The TBD wasn't stressed for dive bombing, which required a vastly heavier structure.

 

[don4331]

It takes a bit more work than outlined above.

Some of the shells have different shaped noses and/or ballistic caps.
Since the shells are not spinning, or not spinning very fast, even with fins you need to make sure you have the desired stability.

AP shells often had an explosive weight of around 2%.
Since the AP bomb no longer has to rotate at high speed and be subjected to tens of thousands of PSI chamber pressure when firing and Since the deck armor is thinner the shells have nowhere near the stress put on them compared to punching through thicker armor.

A lot of the converted battleship shells were bored out with thinner walls so they would hold more explosive.
This also meant they were lighter than the parent Battleship shells.
In some cases the ballistic caps/windshield were removed.

The French didn't expend any more energy than what I outlined - fins were welded on, fuses replaced. Their AP bombs weight exactly the same as the cannon rounds. (I picked the French as they were 18+ months earlier than Japanese and a more improvised solution)

The impact force against an armoured belt is several times greater than forces for firing the round - we're not hitting aluminum and fabric air frames here. The ballistic cap/windshield is very important for penetration when hitting at <90* - it mushrooms to prevent the hard projectile from skipping off the hard armour. Also the 'whipping' action, as round penetrates the armour needs strong walls in the bomb than 1st glance would suggest.

Yes, an ideal AP bomb is different from cannon round, and you can put forth the argument that a bomb with more explosive is better than a cannon round (RN had SAP 12" rounds with ~10% explosives. But for quick and dirty solution, the cannon rounds were made to work just fine.

 

[don4331]

Ju-87R (1000 HP for take off with Jumo 211A) was erstwhile rated for a 1100 lb bomb + two drop tanks, and in 1940, on same power, was rated for a 2200 lb bomb + two drop tanks. Yes, it was not a navalized bomber.

The Ju-87C is more/less a navalized Ju-87R, and it was rated same or higher.

The trick is to have your airplane at flying angle and then increase speed sufficient to fly. Me.109G-2 was modified into FiSK 199 and able to carry an 1,100lb bomb + 2 - 300 litre drop tanks. The Ju-87C achieved the same by using a catapult - there are some advantages to the trapeze carriage.

Now, its very hard on airframes/engines to operate them in that great of an overload situation. But if your aboard HMS Glorious and Gneisenau and Scharnhorst just appeared on horizon, being able to drop a few 12" or 13.5" rounds on their decks might persuade them to bugger off.