1937 to the late 1941: fighter bombers instead of 1-engined bombers?

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tomo pauk

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Apr 3, 2008
It was suggested,IIRC by S Shortround6 at another thread, that Allies might've been better advised to procure fighter-bombers instead of the 1-engined bombers in the similar time frame. So here it is - 1-engined bombers, like the Ju-87, Ba.65, Su-2, Il-2, Battle, A-24, different Japanese 1-engined bombers are not proceeded with, instead the respective countries make and operate fighter-bombers. Whether these are modified historical fighters, or bespoke A/C. All while using the engines, aerodynamics, materials and weapons as it was historically the case; no hand-waving of thousands of the best engines just for this, the FBs will mostly be using what was historically used on the bombers that don't get produced, or the equivalents/modifications available.

Yes, for some countries/AFs this will require changes in doctrine. Obviously the FBs designed in 1937 will be less capable than the ones mooted in 1940.

For the French, since they were mostly using two-engined tactical bombers, the fighter bombers replace those, but can use bigger & better engines.
 
Germany - the He 112A has probably an advantage here since it had a bigger wing than the Bf 109. Once the Jumo 211 is available, install that so both bomb load and performance without the bomb(s) is acceptable.
Italy - something along the lines of Re.2000, or the 'monoplane CR.42'?
Soviet Union - they were already operating the biplanes and I-16 as fighter-bombers. For the new generation, something like I-180 with a bigger wing? Upgrade with M-82 engine when available.
USA - the P-36 looks the part, and was already advertised as a fighter-bomber by the manufacturer. Move to the 1200 HP R-1830s when available.
 
Since we have saved a great of deal of BMW production in the current thread, perhaps we can install the BMW 801s on the Bf 109? The Bf 109X fuselage with wings from Bf 109T to keep the wing loading manageable (keen eye will notice the spoiler on both wings, so sue me ;) ). Pictures of both components nicked from Wikipedia. Two MG 151/20s, two MG FFMs as guns' armament; no cowl guns.
Advantages over the Bf 109 in the fighter-bomber role include the lack of coolant radiators, has an armored oil cooler, more power down low, wider track (2.5m vs. 2m) due to the wider fuselage, better cockpit canopy, greater guns' firepower. Disadvantages vs. the Bf 109 is greater weight and size (although it is still a bit smaller and lighter than the Fw 190), new fuselage needs to be made. Also consumes more fuel per air mile than the V12s - the no free lunch applies as ever. Bigger fuel tank is installed.

109 801.jpg
 
Maybe the CR.42DB (CR.42 with a DB601A engine) for the Italians? First flight was in March 1941 and first production order for 150 airframes was placed in May 1941, but a shortage of engines resulted in the order being cancelled. Vmax clean was 320 mph during tests.

CR.42DB color.jpg



The standard CR.42 was used as a fighter-bomber so I can only assume the DB variant could be even better at the job.
 
Maybe the CR.42DB (CR.42 with a DB601A engine) for the Italians? First flight was in March 1941 and first production order for 150 airframes was placed in May 1941, but a shortage of engines resulted in the order being cancelled. Vmax clean was 320 mph during tests.

This should easily beat the Gladiators, and give Hurricanes something to think about. Shortage of DB 601 engines was indeed the kicker. Original CR.42 was cleared for up to 2 x 160 kg bombs.
If the DB engines were in good supply - the Re.2001 was supposed to do 337 mph, and was eventually cleared for up to 630 kg bomb. These will also be capable to hold their own against the P-40s and tropicalized Spitfires.
 
For the RAF: finally a place for the MB.2?
The Dagger VIII engine was making it's best power down low - 1000 HP at 8750 ft, but just 800 HP at 15000 ft - making it better for the low altitudes where we can expect the FB to be used, and not so good for bombing Germany from 17000-18000 ft. Does not draw on Merlins' and Hercules' production - RAF has barely a place for the Dagger either as a fighter engine or a bomber engine. Also no draw for production of Spitfires and Hurricanes ordered for the FC.
Being air cooled makes it less susceptible to the battle damage, does not add the drag & weight via the coolant radiator.
MB.2 might get the retractable U/C for lower drag, even it the proposed system was barely more streamlined than what P-35 had. Nip & tuck is still needed, like a better prop, exhausts (pointed backward), protection for pilot and fuel.
 
For the RAF: finally a place for the MB.2?
The Dagger VIII engine was making it's best power down low - 1000 HP at 8750 ft, but just 800 HP at 15000 ft - making it better for the low altitudes where we can expect the FB to be used, and not so good for bombing Germany from 17000-18000 ft. Does not draw on Merlins' and Hercules' production - RAF has barely a place for the Dagger either as a fighter engine or a bomber engine. Also no draw for production of Spitfires and Hurricanes ordered for the FC.
Being air cooled makes it less susceptible to the battle damage, does not add the drag & weight via the coolant radiator.
MB.2 might get the retractable U/C for lower drag, even it the proposed system was barely more streamlined than what P-35 had. Nip & tuck is still needed, like a better prop, exhausts (pointed backward), protection for pilot and fuel.
Also Martin Baker made a far better job of cooling it than Napier.
 
Also Martin Baker made a far better job of cooling it than Napier.
did they?
Seems to be some confusion as to which engine the M.B.2 got. Or maybe it had more than one?

It seems to have been the Dagger IIIM of 825hp at 4000ft, 2.25lbs at 4000rpm. and 700hp for take-off at 3,500rpm and 3.5lbs boost. I don't know if this was because of the fixe pitch prop.

The 1000hp engine was the VIII but that doesn't seem to show up until the Hereford. there were a number of changes, one of which was spur reduction gear.
raf-bomber-command-1940-hu104644-22e6d1-640.jpg
handley-page-hp52-hereford-l6003-9892781.jpg.webp

45-_Handley_Page_Hp.52_Hampden_and_Hereford._CH155.jpg

Note that the top of the prop spinner is almost inline with the upper exhaust stacks while the lower edge of spinner is offset above the lower exhaust.

I don't know how bad the Hawker Hectors were for cooling. It the is the Herefords that get most of the bad press.
The Dagger VIII got a new supercharger, and is also supposed to have gotten increased cooling fin area. Considering they were trying to pull about 200hp (30%) more out of it at take-off that is understandable.

If the MB 2 reached it's performance on the lower power engine that is very commendable, but the service use of the higher powered version of the engine was pretty dismal.
Maybe it could have been fixed or maybe it needed a lot more work (like even more fin area and other changes).
 
From the current thread:

You are going to be hard pressed to keep it smaller than a P-40.

1939-40 air cooling and lack of exhaust thrust (design perspective)
1900lb engine.
The US is going to want at least 200 US gallons of fuel (P-36 has around 160gal without drop tank and without self sealing. P-39 was supposed to have 200gal before self sealing)
As you have said, it is a thirsty engine (I agree, 150 US gal/hr at 1275hp at 12,000ft, more at full power)

Just for context
XSB2C-1 photo may date from Aug 1941 as several features in the photo series date from then.
Brewster Buccaneer prototype, summer of 1941
Just the state of the art in cowling, exhaust in 1940-41 in the US.

You need every bit of the 1400hp to to overcome the drag compared to the V-1710 in the P-40.
Granted you can make the Fuselage considerably smaller and no cowl guns) but you can't stick this thing on a P-36/40 without longer landing gear legs.

The early A-20 were pretty zippy, despite the big radials, heavy weight, thick (18% t-t-c root) and big wing, lack of finesse wrt. exhaust stacks, and it's portly fuselage. 333 mph for the A-20B at 5000 ft (2x 1570 HP used), 349 mph at 12050 ft (2 x 1400 HP). That is within 2+- mph vs. the gun-armed Mosquito per this test at these altitudes, +12 lb boost used, ie. with ram ~1300 HP at S/L, and ~1400 HP at 12000 ft. The V-1710 was much worse than that in 1940-41, 1000-1150 is the best what can be expected when going from SL to 12000 ft.
Sometimes just having the brute force is an advantage; finesse - like the better exhausts - can come in later, so can a 1700 HP R-2600.
 
It was suggested,IIRC by S Shortround6 at another thread, that Allies might've been better advised to procure fighter-bombers instead of the 1-engined bombers in the similar time frame. So here it is - 1-engined bombers, like the Ju-87, Ba.65, Su-2, Il-2, Battle, A-24, different Japanese 1-engined bombers are not proceeded with, instead the respective countries make and operate fighter-bombers. Whether these are modified historical fighters, or bespoke A/C. All while using the engines, aerodynamics, materials and weapons as it was historically the case; no hand-waving of thousands of the best engines just for this, the FBs will mostly be using what was historically used on the bombers that don't get produced, or the equivalents/modifications available.

Yes, for some countries/AFs this will require changes in doctrine. Obviously the FBs designed in 1937 will be less capable than the ones mooted in 1940.

For the French, since they were mostly using two-engined tactical bombers, the fighter bombers replace those, but can use bigger & better engines.
Was the doctrine in place for fighter bombers? The Fairey Battle and Junders Ju87 were specialised tactical bombers, for which the need for air superiority was not obvious enough.

A lot of WWII fighter bombers were fighter aircraft that were no longer up to the task of air superiority and interception. They were fast enough to be hard to intercept, and they would be escorted to the target. Think about P40s, Hawker Hurricanes and possibly Fw190Fs and Gs. P47 Thunderbolts would have been eaten for breakfast by a Luftwaffe whose experienced pilots had not been slaughtered at the P47's preferred altitudes of 30,000ft+. It helped that all of these aircraft were rugged. What were Spitfire_Vs doing after D-Day?

The Hawker Typhoons were successful fighter bombers because they were fast at low altitude and they were sturdy. They were in fact designed as high altitude interceptors. The universe did not enfold as intended.
 
Was the doctrine in place for fighter bombers? The Fairey Battle and Junders Ju87 were specialised tactical bombers, for which the need for air superiority was not obvious enough.
Idea behind the Battle was strategic bomber on the cheap. That backfired badly.
Before 1940, doctrine for fighter bombers was probably in place with USMC? Germans adopted the doctrine with bombed-up BF 110s and 109s in 1940, Soviets were doing the same with biplane fighters.
Italian Ba 65 was probably the 1st aircraft that was supposed to be a fighter-bomber (aeroplano di combattimento), again that backfired badly.

Backk in the Great war, there were fighters that were also supposed to toss grenades and small bombs on the ground units, as this A/C for example. Granted, many lessons of the ww1 were soon forgotten.

The Hawker Typhoons were successful fighter bombers because they were fast at low altitude and they were sturdy. They were in fact designed as high altitude interceptors. The universe did not enfold as intended.

Neither the engine chosen nor wing size point out that Typhoon was designed as a high altitude interceptor.
 
The Hawker Typhoons were successful fighter bombers because they were fast at low altitude and they were sturdy. They were in fact designed as high altitude interceptors. The universe did not enfold as intended.
Spec F.18/37 that led to the Typhoon called for a high speed single seater fighter as a replacement for the Hurricane & Spitfire. The speed requirement was 400+mph at 15,000 ft. While the service ceiling was to be 35,000+ft, that was not much more than Spitfire I was capable of in 1939.
 
Soviet Union - they were already operating the biplanes and I-16 as fighter-bombers. For the new generation, something like I-180 with a bigger wing? Upgrade with M-82 engine when available.
I-207 (required low-octane B-70 gasoline, could carry a 500 kilogram bomb load), then I-153 (required B-78 gasoline). The I-16 was less suitable as FB due to difficulties with the suspension of bombs larger than 100 kg when taking off from the ground (although there were examples of successful ground attack missions when launching from the TB-3 in the air). According to some reports, the I-153 suffered lower losses and inflicted similar damage when bombing ground targets compared to the Il-2 (the latter's concept was rather flawed). "Upgrade" of I-180 with M-82 was I-185. A "bigger wing" means rather a completely new aircraft in this case. But the idea to use widely biplanes as FB in the soviet AF seems very reasonable.
 
Backk in the Great war, there were fighters that were also supposed to toss grenades and small bombs on the ground units, as this A/C for example. Granted, many lessons of the ww1 were soon forgotten.
See

Granted the bombload was light but 605lbs of metal around the pilot and fuel means it as sort of a WW I IL-2 ;)
Neither the engine chosen nor wing size point out that Typhoon was designed as a high altitude interceptor.
Answered by EwenS but many times designed as changes considerably when the plane is "introduced as" in combat service in the first squadron/s.
4 years was long, long time in the late 30s/early 40s.
 
A "bigger wing" means rather a completely new aircraft in this case. But the idea to use widely biplanes as FB in the soviet AF seems very reasonable.

"Upgrade" of I-180 with M-82 was I-185

A lot of times swapping engines results it a completely new aircraft. Changing from the M-62/M-63 9 cylinder radials to the M-82 14 cylinder radial is very much like like going from an R-1820 Cyclone 9 (cousin to the M-62/M-63) to the R-2600 (a bit more distant cousin to the M-82).
 
A lot of times swapping engines results it a completely new aircraft.
It was still a consequent development of the I-180 with the same technology originating from the I-16. The situation with the engine development in the USSR at that time was rather very disappointing and required more flexibility from aircraft designers. The I-180 was equipped with M-87/M-88 and the I-185 initially was designed for M-90 of the same line originating from Gnome-Rhône 9K/14K. But the concept of the I-185 (a relatively small fighter with a dense layout and high wing loading) made it less suitable for FB role. Small biplanes with relatively low wing loading and high maneuverability with sufficient speed characteristics were better suited for this purpose.
 
Hi,

I think a big issue here, as the OP kind of alluded to in his post, is that things will vary greatly over time. And to be honest in the time frame under discussion is that 6 months can seem like a lifetime. If you want a plane to be available in 1937 you may have to rely on technology that is available in 1934 or so, unless you're willing to try and design around an under development engine that may either not live up to expectations, or get canceled before it enters service.

For reference, looking at Wikipedia and a couple other sites on the web, in 1937 the following designs had their first flight, though many did not enter production til a year or two later:

Bombers/Attack Aircraft:
UK:
  • Blackburn Skua with a 890HP engine (entered production 1938) - 500lb bomb capacity
  • Fairey P.4/34 with a 1030HP engine(did not enter production) - 500lb bomb capacity
Japan:
  • Mitsubishi Ki-30 with a 949HP engine (entered production 1938) - 882lb bomb capacity
  • Kawasaki Ki-32 with a 850 HP engine (entered production 1938) - 990lb total bomb capacity
  • Mitsubishi B5M with a 1000HP engine (entered production 1937) - 1760lb capacity
  • Nakajima B5N with a 770HP engine (entered service 1938) - 1765lb torpedo or 750lb bomb capacity (?)
USSR:
  • Sukhoi BB-1/Su-2 with 1000HP engine (entered lproduction 1939) - 880lb bomb capacity (?)
Poland:
  • PZL.43 with a 900-930HP engine (entered production 1937) - 1543lb bomb capacity (?)
Fighters:
US:
  • Curtiss YP-37 with a 1000HP engine (did not enter production)
  • Brewster F2A with a 950HP engine (entered production in 1939)
  • Grumman XF4F-1 with a
UK:
  • Bolton Paul Defiant with a 1030HP engine (entered production 1939)
  • Gloster F.5/34 with a 840 HP engine (did not enter production)
France:
  • Block MB 150 with a 940HP engine (entered production 1939)
Italy:
  • Fiat G.50 Frecia with a 870HP engine (entered production 1938)
  • IMAM Ro.51 with 840HP engine (did not enter production)
  • Macchi C.200 Saetta with a 870HP engine (entered production 1939)
Dutch:
  • Koolhaven F.K.52 with a 838HP engine (entered limited production 1939)
USSR:
  • Polikarpov I-153 with a 750HP engine (although intended to fit a 801HP engine that wasn't initially available (entered production 1939)
Belgium:
  • R.36 with a 910HP engine (did not enter production)
Additionally, lookimg at the specs for the P-36/H-75 (fitted with a 1000HP engine) noted as a possible example of an ealry fighter/bomber it appears that tat design was rated to carry up to 300lb of small bombs (25 to 50lb ea) with the ability to fit additional bomb racks for 1 x 500lb and 2 x 100 lb bombs. The total weight of the plane if fitted with a 1 x 500lb bomb and 2 x 100lb bombs is listed as 2347 + 4713lb = 7060lb (for the plane if fitted with a Pratt & Whitney Twin Wasp S3C3-G engine of 1100HP @ take off) or 2347 + 4483lb = 6830lb (for the plane if fitted with a Curtiss Wright GR 1820-G105A engine of 1100HP @ take off).

Additionally when outfitted above with the 500lb and two 100lb bombs the plane is only outfitted with its fuselage mounted single 30 cal and single 50 cal machine guns and their ammunition, and no wing mounted guns or their ammunition. Unfortunately the attainable speed for the plane in such a load out is not provided, though it is noted as being 303mph for the CW engined variant @ 19,000 ft when configured as a fighter @ a 5692lb normal gross weight, vice the 6830lb weight when configured as a fighter bomber with the CW engine (an 1138lb or about a 20% greater weight).

For the plane when fitted with the P&W engine the numbers listed are 323mph @ 15,300 ft @ 5922lb normal gross weight vice the 7060lb weight when confired as a fighter/bomber with the P&W engine (an 1138lb or 19.2% greater weight).

For the plane with either engine though a quick look through the spec does not appear to mention anything like armor or self-sealing fuel tanks.

Looking at the bomber attack aircraft being tested in 1937, listed above, such a figher bomber may potentially compare favorably to a plane such as the P.4/34 or Skua design, but I'm not fully convinced that it would be a great trade-off against some of the plane capable of heavier payloads.

As such, at least in the early part of the time frame considered I'm not convinced that replacing all single engined bomber/attack craft with fighter/bomber would necessarily be a great idea, especially since not all the fighters noted above had access to the notionally 1100HP (@ take off) engines listed for the H-75A design.

Regards

Pat
 
To further some of what PFVA63 has said the Hawk 75 was using engines that ran on 90-100 octane fuel (but not 100/130).

Some countries needed new engines (basically larger/heavier engines) to get more power.
Some fighters were never going to be good load carriers.
The Hawk 75 used the same size wing as P-40 even if not quite as sturdy. 236 sq ft, put that together with 1000-1200hp of engine and you have a decent chance of carrying a load (no armor or self sealing tanks) The Bloch 152 had a 186 sq ft wing. even with a 1000-1100hp engine things are getting a bit iffy.

We are back to the fixed load argument. You need the 200lb pilot, the instruments, the radio and so on.

For an idea of what the biplanes could do see the HS 123 dive bomber
Wingspan: 10.5 m (34 ft 5 in)
Wing area: 24.85 m2 (267.5 sq ft)
Empty weight: 1,500 kg (3,307 lb)
Gross weight: 2,215 kg (4,883 lb)

Powerplant: 1 × BMW 132Dc 9-cylinder air-cooled radial piston engine, 660 kW (880 hp)

Maximum speed: 341 km/h (212 mph, 184 kn) at 1,200 m (3,900 ft)
Range: 860 km (530 mi, 460 nmi) with drop tank[16]
Combat range: 480 km (300 mi, 260 nmi) with 200 kg (440 lb) of bombs

2× 7.92 mm MG 17 machine guns, 400 rpg (field modification of 2× 20 mm (0.79 in) MG FF cannon)
Up to 450 kg (992.1 lb) of bombs (1 x SC250 bomb under fuselage and 4 x SC50 bombs under wings) (never carried?)

British screwed themselves with the propellers. Maybe a Gladiator bomber would have been a good idea, but you need something better than than fixed pitch prop.
trying to use the Defiant as a base runs into the usual Defiant problem, without a redesign the airframe is too heavy doe to being beefed up to take the turret and a two pitch prop is not that good an idea for a bomber anyway. Also sticking high altitude (for 1937-38) engines in ground attack planes wasn't a good idea.

I-153 wasn't that good an idea. Even if you get the engine straightened out it had a small wing for a biplane.

As fighters got more powerful they could handle more weight, the pilots and cockpit weights stayed the same, there was more power that could be used for payload.
 
It was suggested,IIRC by S Shortround6 at another thread, that Allies might've been better advised to procure fighter-bombers instead of the 1-engined bombers in the similar time frame. So here it is - 1-engined bombers, like the Ju-87, Ba.65, Su-2, Il-2, Battle, A-24, different Japanese 1-engined bombers are not proceeded with, instead the respective countries make and operate fighter-bombers. Whether these are modified historical fighters, or bespoke A/C. All while using the engines, aerodynamics, materials and weapons as it was historically the case; no hand-waving of thousands of the best engines just for this, the FBs will mostly be using what was historically used on the bombers that don't get produced, or the equivalents/modifications available.

If the starting point is 1937, I wonder if the powers-that-be would require a fighter-bomber to have defensive armament, as they did for the 1-engine bombers of the time.

The Defiant with fixed forward guns and the rear turret and fitted with a bomb rack or racks could do the job.

If the radiator was moved to under the nose, Miles M.20 style, a bomb could be carried under the fuselage.
 
If the starting point is 1937, I wonder if the powers-that-be would require a fighter-bomber to have defensive armament, as they did for the 1-engine bombers of the time.

The Defiant with fixed forward guns and the rear turret and fitted with a bomb rack or racks could do the job.

If the radiator was moved to under the nose, Miles M.20 style, a bomb could be carried under the fuselage.
Not without resorting to the old "jiggery pokery " :)
Picture of model

Air_BP_defiant_39.jpg

OK we can move the landing gear out around 1 1/2 feet or 2 ft ?
But then the landing gear is taking up part of the fuel tank space.
And we want some of the fuel tank space to put the forward firing guns in.
But we can put the fuel in the fuselage and move the pilot backwards
and then we can............................................

For crying out loud.
Beef up the wing on a Hurricane a little bit, hang a 250lb bomb under each wing and sign the pact with devil and get a constant speed prop 1-2 years early if you want a fighter bomber in 1938.
Want a pair of 500lbs under the wings in 1940?
Swipe some Merlin VIIIs from the Fulmar for an extra few hundred horsepower on take-off using 87 octane fuel.

KISS, Keep It Simple Stu***
 

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