1936 to mid-42: fast 1-engined bombers instead of slow types?

[tomo pauk]

Basically, Germans don't accept the dive-bombing doctrine so there is no Ju 87 as we know it, while British make a fast bomber instead of Battle or Henley (yes, the last one never bombed anything beyond the target range, but still). Italians make something much better than the Ba.65, Polish got something more streamlined than the PZL.23. Americans, Soviets and Japanese can also compete here. Ditto for Yugoslavia, Romania, Sweden, Czechoslovakia, Belgium, Netherlands, Australia...
These alternative bombers still have at least 2 crew members; they should use engines, guns and aerodynamics of the day, and start without a meaningful protection. Preferably designed with bomb bay, or at least with a recess to house the payload. Range needs to be good (Battle was carrying double the fuel when compared with Hurricane), bomb load should be at least at 500 kg or 1000 lbs. Max two MGs forward, at least one MG in defensive position.

Please note that this is not about fighter bombers, and also this is not about carrier-borne types.

Possible pointers might be the Ca.335, Ca.355, as well as the D4Y (late for this thread, but even with modest power was good for ~330 mph in it's 1st versions).

 

[Shortround6]

Engines and time.

For the US in 1936-38 you are very lucky to have a 1000hp engine for take-off.
In 1941/42 you can swipe 1850hp engines from the B-26
Two totally different aircraft.

The Battle gets no love. In 1936 what are you going to do to make anything any better?
The Henley was only carrying 1/2 your desired bomb load and carried just 1/2 the amount of fuel.
Add 500lbs to Henley (and a slightly fatter fuselage) and even another 350lbs of fuel and you may need another 35-36 sq ft of wing area to get the same take-off and landing performance using the Merlin III and two pitch prop. Where is you speed now ?

Basically you have a choice.
Speed
Bombload
Range

Pick one.

Caproni Ca.335 Maestrale
Bomb load is 440lbs?
1/2 carried outside so listed speed falls.
Wing area is about that of a Hurricane so how big is the needed landing field.

Beef up the structure, increase power, make the bomb bay bigger (a pair of 250lb bombs?)
And range drops, Add fuel to get range back, speed drops, and so it goes.
Better H-S engine or Merlin III, you aren't going to get over 300mph, over 1000 miles and close to a 1000lb bombload.

 

[Topknot]

P4/34 had a speed of 280 plus and bomb load of 500 lbs. using the usual early Merlin II (1,030 hp.) engine. Maybe push development forward the Fulmar with Merlin 30 (1,300 hp) and 4 wing guns instead of 8 ? Published range is close to 800 miles.

 

[tomo pauk]

Engines and time.

For the US in 1936-38 you are very lucky to have a 1000hp engine for take-off.
In 1941/42 you can swipe 1850hp engines from the B-26
Two totally different aircraft.

Americans can start with R-1830 and then make a switch to the R-2600. Talk half of DB-7 -> A-20 recipe. Germans did make a switch from 650-700 HP Ju 87 and Bf 109 into the 1000-1100-1200 HP versions. Pretty similar aircraft, but the up-engined types were much better.
A switch from R-1830 to V-1710 is another possibility.

Basically you have a choice.
Speed
Bombload
Range

Pick one.

I've already sacrificed the drop-tanks facility and 1000 kg bomb load, like it was the case with Ju 87R1 with 1000 HP engine (or the ability for a 750 kg bomb with SDB). Or with the TBD that carried a 1000 kg torpedo.
I've also sacrified the 3rd crew member (= shorter cockpit = less weight + less drag), as well as protection before 1940.
Thus I'd pick two - speed and range.

Caproni Ca.335 Maestrale
Bomb load is 440lbs?
1/2 carried outside so listed speed falls.
Wing area is about that of a Hurricane so how big is the needed landing field.

Landing field is pretty short, due to a bit higher wing loading.
The 355 was supposed to be better, 400 kg bomb load (880 lbs); yes, it needs at least the recess for the bomb in order to cut the drag and improve speed towards the target.

The Battle gets no love. In 1936 what are you going to do to make anything any better?
The Henley was only carrying 1/2 your desired bomb load and carried just 1/2 the amount of fuel.
Add 500lbs to Henley (and a slightly fatter fuselage) and even another 350lbs of fuel and you may need another 35-36 sq ft of wing area to get the same take-off and landing performance using the Merlin III and two pitch prop. Where is you speed now ?

Battle was too big. The 3-men cockpit meant the big fuselage, while wing was supposed to carry both fuel and bombs, thus the wing eneded up being both of big thickness (in absolute terms), of big thickness-to-chord ratio of 18% (ie. in relative terms), and of big area. Wing area was between that of the Bf 110 and A-20 (or Mosquito). All 4 bullet points together make for a draggy and heavy aircraft. A heavy and draggy aircraft will get the worse mileage than a light and sleek one, as seen with Bf 109E vs. MC.202 (former, cruising at 360 km/h, has the worse range than the later cruising at 390 km/h, or even when the later is flying at 470 km/h; all for 6000 m cruising altitude).
I'd go with two 500 lb bombs carried in tandem for starters, a wing of 15% (root) and of 250-270 sq ft. 150 imp gals of fuel. Merlin III, 'beard' radiator, with 2-speed propeller by De Havilland. Wheels retracting outwards, with wheel well covers. Modes gun firepower.
Outwards it is basically a big, 2-seater P-40.

 

[Macandy]

The lessons learned - at least by the Americans - of the Spanish Civil War was, underpowered light bombers fly slow, and die fast.

The Douglas A-20 was the right answer.

 

[A.G. Williams]

As I recall, the Fulmar was a scaled-down Battle and was originally intended for the light bomber role.

 

[GrauGeist]

Bulgaria had a native design, the DAR 10, which may have been more successful if it weren't for issues with the engine selection. 1 prototype was fitted with a Fiat engine, the other with an Alfa-Romeo engine.

 

[tomo pauk]

The lessons learned - at least by the Americans - of the Spanish Civil War was, underpowered light bombers fly slow, and die fast.

The Douglas A-20 was the right answer.

A-20 was okay for 1942. There is another 6 years before 1942 - and indeed a whole SCW - to make the things ... less wrong, if not right
Nobody is suggesting that bombers need to be under-powered, too.

 

[Shortround6]

Americans can start with R-1830 and then make a switch to the R-2600. Talk half of DB-7 -> A-20 recipe.

OK, the DB-7 weighed about 11,700lbs empty, the A-20G weighed almost 17,000lbs empty.
The A-20B went about 14,830 pounds empty, had no armor, no protection for the fuel tanks.
It was fast
It was also rated at 800 mile range with 1000lbs of bombs
You could swap fuel for bombs and carry a heavier load a shorter distance or less bombs a longer distance.

Please note the 3000lb empty weight increase for a pair of engines that "only" weighed about 1000lbs more for the pair.

So how does this "half" DB-7 -> A-20 recipe work?
400 mile range with 500lbs of bombs with the R-1830 engine?
Or 400 miles with 1000lb/800 miles with 500lbs?
The original DB-7 held 325 US gallons of fuel. 165 US gallons equals 137 Imp gallons.

Lets see how this works out..

Take a P-36 (wing about 1/2 the size of the DB-7 wing) Keep the R-1830 in the nose, take out the behind the pilot fuel tank and stretch the fuselage a bit to get in the 2nd crew man.
pad out the fuselage a bit to hold a pair of 250lb bombs and maybe you can put a small tank out in each wing to restore the fuel you took out from the fuselage.

Depending on the fuselage bomb bay you might get the plane to 300mph.

 

[tomo pauk]

OK, the DB-7 weighed about 11,700lbs empty, the A-20G weighed almost 17,000lbs empty.
The A-20B went about 14,830 pounds empty, had no armor, no protection for the fuel tanks.
It was fast
It was also rated at 800 mile range with 1000lbs of bombs
You could swap fuel for bombs and carry a heavier load a shorter distance or less bombs a longer distance.

Please note the 3000lb empty weight increase for a pair of engines that "only" weighed about 1000lbs more for the pair.

The A-20 'gained' at least the heavier structure in the wing, heavier engine bearers, cowlings, oil system, prop. Tail was also bigger and heavier. Landing gear too.
Being of the attack role, the fuel carried was pretty low for the thirsty R-2600s on the A-20s, as well as on the DB-7s for the R-1830s. Yes, late versions gotten a 'proper' fuel load.

So how does this "half" DB-7 -> A-20 recipe work?
400 mile range with 500lbs of bombs with the R-1830 engine?
Or 400 miles with 1000lb/800 miles with 500lbs?
The original DB-7 held 325 US gallons of fuel. 165 US gallons equals 137 Imp gallons.

Lets see how this works out..

Take a P-36 (wing about 1/2 the size of the DB-7 wing) Keep the R-1830 in the nose, take out the behind the pilot fuel tank and stretch the fuselage a bit to get in the 2nd crew man.
pad out the fuselage a bit to hold a pair of 250lb bombs and maybe you can put a small tank out in each wing to restore the fuel you took out from the fuselage.

Wing of the P-36 is too intersected internally, much due to having five spars. Even the P-39C started out with 170 gals in the unprotected wing tanks (yes, no guns there yet), but introduction of self sealing played havoc with 12 fuel cells stealing the useful volume.
So I'd go with 1- or 2-spar wing, since here most/all of the fuel goes. 170-180 gals in two tanks. Wing size & profile of what P-36/-40 had will work with R-1830 and V-1710. For the R-2600 we'd want a bit bigger wing, but still well under 300 sq ft. Bomb recess behind the lower portion of the radial engine (or behind the radiator if the V-1710 is installed).

BTW - the wing area on the A-20/DB-7 was double of what P-36 had, but the wing was also much thicker, and with greater t-t-c ratio - 18% vs. 15%. There is also a thing of two radials on the wings trying to push the aircraft throught the air, not something an 1-wngined A/C will had.

Depending on the fuselage bomb bay you might get the plane to 300mph.

Later P-36 powered with R-1820s were said to be good for 320+ mph. Let's not sell short the version with a lot more power.

 

[GrauGeist]

Aa far as single-engine bombers during the mentioned time period, the U.S. had the Northrop A-17, Curtiss A-12 and Douglas A-33.

 

[Wildcat]

Vickers Wellesley. Great range, 2000lb bomb load though it needs better defensive armament.

 

[Shortround6]

Vickers Wellesley. Great range, 2000lb bomb load though it needs better defensive armament.

OK, you got two out of three

But it is more than a bit difficult to see the Wellesley as fast.

 

[muskeg13]

Aa far as single-engine bombers during the mentioned time period, the U.S. had the Northrop A-17, Curtiss A-12 and Douglas A-33.

Plus, the Douglas A-24, Vultee A-31 and the Curtiss A-25. While this thread is not about carrier borne bombers, nearly all of the US manufacturers of naval scout bombers ended up producing a land-based variant for the Army, Marines or for export.

 

[GrauGeist]

Plus, the Douglas A-24, Vultee A-31 and the Curtiss A-45. While this thread is not about carrier borne bombers, nearly all of the US manufacturers of naval scout bombers ended up producing a land-based variant for the Army, Marines or for export.

I left out the Dive Bombers because Tomo was looking for a single-engine substitute for a twin-engine level bomber.

 

[tomo pauk]

I left out the Dive Bombers because Tomo was looking for a single-engine substitute for a twin-engine level bomber.

Dave - I was trying to replace the slow 1-engined bombers with a fast(-ish) 1-engined bombers. Eg. Germany adopts sorta trimmed-down He-118 (or a scaled-up Bf 109B but a 2-seater, with DB 600 at least in the nose and with beard radiator) instead of Ju 87; British make something much smaller and a bit lighter than the Battle. Americans - no A-24 as we know it, but they go with a bomber that resembles a big 2-seat P-36/-40 etc. Soviets follow the suit, instead of going with Su-2. Yes, the Soviet fast 1-engined bomber made around the AM-35A (and later around the AM-38) would've been also interesting, adopted instead of the Il-2.

 

[special ed]

Perhaps the He 70?

 

[Macandy]

A-20 was okay for 1942. There is another 6 years before 1942 - and indeed a whole SCW - to make the things ... less wrong, if not right
Nobody is suggesting that bombers need to be under-powered, too.

However, the entered into service in 1942 A-20 was off the back of lessons well learned in the 1930's.
Single engine + Bomber = slow dog

The A-20 was a very hot ship - it hit the spot, and the aim point.

 

[tomo pauk]

However, the entered into service in 1942 A-20 was off the back of lessons well learned in the 1930's. The A-20 was a very hot ship - it hit the spot, and the aim point.

Nobody here has anything against the A-20, yet it ill fits into this thread.

Single engine + Bomber = slow dog

Seems like the people at Yokosuka didn't gotten the memo, with their bomber doing 335 mph on 1 engine no better than the V-1710-39.

 

[Shortround6]

What does a single engine bomber bring to the table?

As in what do 200 single bombers that can move 1000lbs apiece 400miles (radius) do for you that 100 twin engine bombers that can move 2000lbs each 400 miles (radius) at the same speeds?

Or change one of criteria. even with 1/2 the bomb load is the single going to be faster, even if shorter ranged.

different countries had different criteria or doctrine or requires.

For the US for attack planes (light tactical bombers) they had gone from liquid cooled engines to air cooled engines to reduce the danger from ground fire in the early 30s.
By the late 30s (1937-38) they wanted twin engine planes, perhaps with the idea that the twin could make it home of one engine? The US was one of the leaders in constant speed propellers making it easier to fly on one engine. It took another 2 years or so to put self sealing fuel tanks in though.
Unless you change US thinking they weren't going to order a single engine liquid cooled engine bomber.
Other countries would, in part because their liquid cooled engines were further ahead than their air cooled engines.

BTW the He 118 was a bad example. It used a wing about 96% of the size of a Battle's wing and since it first flew in 1936 it's aerodynamics were not any better than the Battle's.

You need a new wing