1939 Tactical Bomber

[Howard Gibson]

tomo pauk suggested a new thread for this...

It's 1935. Dive bombers and other light bombers are all the rage, but you are perceptive and smart. You recognise that hostile ground forces will be equipped with anti-aircraft guns, and there is no guarantee you will have air superiority. Your bomber must look after itself.

The effectiveness of defensive firepower was grossly overrated in the late thirties, but if you are British, you have studies that show it takes eight .303s to reliably destroy an enemy aircraft. Are you perceptive enough? Armour that stops rifle calibre ammunition looks like a good idea.

Your primary weapon is bombs. Fixed forward gun armament can work against fighters and ground targets. Large cannons are a possibility.

Since this is a tactical bomber, there is no need for high altitude performance. Your aircraft can be optimised for speed below 10,000ft.

Design or describe a light bomber that will survive your anticipated conditions.

• Your engine (or engines) must be in production by 1939.
• Your weapons must be in production in 1939.
• Your aircraft must reach production in 1939.
• Your most serious victims will 1939 vintage armour, although we need to speculate on how you will cope with the heavier armour that will soon appear.
• Your protection is some combination of fighter level speed, defensive firepower and/or armour.
• Your aircraft should be able to operate from crude airfields close to the front line, allowing multiple missions per day. There is no need for long range.
• Your tactics minimise your exposure to ground fire, i.e., no vertical dive bombing. Maybe an extra crew can help with navigation and target spotting. Can you do radio communication with ground forces?

 

[Shortround6]

Fairey Battle.

• Your engine (or engines) must be in production by 1939. Check, use Merlin VIII or Merlin X locked in low gear. Steal constant speed propellers.
• Your weapons must be in production in 1939. Check.
• Your aircraft must reach production in 1939. Check
• Your most serious victims will 1939 vintage armour, although we need to speculate on how you will cope with the heavier armour that will soon appear. Lots of small bombs. 4 .303s for strafing)
• Your protection is some combination of fighter level speed, defensive firepower and/or armour. Armor for rear gunner, pilot, radiator, protection for fuel tanks (even cooled exhaust gas, better if you can)
• Your aircraft should be able to operate from crude airfields close to the front line, allowing multiple missions per day. There is no need for long range. (fit half size fuel tanks, use weight for protection)
• Your tactics minimise your exposure to ground fire, i.e., no vertical dive bombing. Maybe an extra crew can help with navigation and target spotting. Can you do radio communication with ground forces? 2 seats for sure, to handle radio.

Hedge hopping, two .303s out the back. Preferably Brownings.

 

[tomo pauk]

I'd go for speed as the best defense. 2-engined design should allow for a bit of a leeway wrt. the engine choice and guns' placement
For the British, Merlin is probably the best bet. For the Germans, DB 601.
Americans will probably use the R-1830.

Size needs to be kept modest, talk size between the Fw 187 and Whirlwind/Ro.58.
20mm 'full-power' cannons (like the MG30C/L or Oerlikon S) will make a short work of many late 1930s tanks, while a few countries can try with 25 or 37/40mm self-loading pieces. MG FF and Shvak will not cut it vs. tanks.

If 1-engined type is preferred, a bombed-up 2-seat Hurricane is already there.

 

[Howard Gibson]

Fairey Battle.

The aircraft must be successful. The Fairey Battle is what they should have anticipated.

 

[Thumpalumpacus]

DB-7?

 

[Shortround6]

The Battle had everything going against it.
Nobodies' light attack aircraft would have done any better if flown using the same tactics and escorting that the Battle got.

So lets try looking at the German Bf 110 in 1939.
Little or no armor.
No self sealing tanks.
20mm MG FF guns are not very good at taking out tanks.
rough field capability?
Max speed of 295mph at sea level?
Max continuous at sea level 262mph?
No bombs *

The 1940 Bf 110C-4 got the bomb racks but it also got the DB 601N engines with more power.

This is where we get into conflicting requirements.

Your aircraft should be able to operate from crude airfields close to the front line, allowing multiple missions per day. There is no need for long range

Bf 110C-1 was good for about 481 miles at the 262mph speed at sea level, Now maybe that is more than what is wanted but the plane has about 70% of the range of the Battle at altitude (217mph for the Bf 110 and 200mph for the Battle) so you don't have as much as some people may think.
Battle's big wing that hurts speed gives it a landing speed of 60mph.
There is one of the trade-offs, you want to get out off (and into) crappy airfields with 1939, low powered engines you need a big wing.
The Blenheim I was practically STOL. 469sq ft, 12,500lbs, Take-off run 296 yds, landing run, 364 yds (with Brakes), landing speed 50mph. (data from old Janes (?)

You want small crappy airstrips you give up performance. What are you willing to trade?
you also need at least some range, if you are advancing several dozens of miles in a day you may not have to move everyday but the Germans moved around 150-170 miles from the Border to Dunkirk, Every time you move airfields you have to move the ground crew, the bomb/ammunition supply, spare parts and arrange for at least some fuel, you can't count on capturing all the fuel you need. You have to leap frog support units. Some still perform support will other units move to forward (or captured air fields), The Units that move may be able to fly the same day but not for very long or with much in the way of bombs/ammo.

Ideal requirements are like the camel. We may have to decide if we want a small horse or pack mule instead of the camel.

 

[tomo pauk]

No bombs *

The 1940 Bf 110C-4 got the bomb racks but it also got the DB 601N engines with more power.

I hope that we will not arrive to a conclusion that the 'normal' Bf 1109C, powered by the DB 601As, will not be able to carry bombs.

Bf 110C-1 was good for about 481 miles at the 262mph speed at sea level, Now maybe that is more than what is wanted but the plane has about 70% of the range of the Battle at altitude (217mph for the Bf 110 and 200mph for the Battle) so you don't have as much as some people may think.

There is no need that any aircraft flies 100% of it's sortie at sea level. Even if it is a tactical bomber.

 

[Shortround6]

I hope that we will not arrive to a conclusion that the 'normal' Bf 1109C, powered by the DB 601As, will not be able to carry bombs.



There is no need that any aircraft flies 100% of it's sortie at sea level. Even if it is a tactical bomber.

The 110C-1 can carry bombs, it just needs a bit more runway than the C-4.

Just trying to put things into context for range. The 110 was considered long range by some. It might have more than what is wanted for tactical support but the tactical support aircraft that is wanted in relatively static/slow moving battle may not the the tactical support aircraft that is ideal for fast moving battle campaign.

It may turn out that short range interdiction/supply dump raiding/enemy airfield raiding was more important than flying around trying to pot tanks with larger caliber guns from the air.
Reduce the number of enemy bombers, blow up their artillery/ bomb / fuel dumps may be more important that flying right over the battlefield (although not as good for morale).

 

[tomo pauk]

The 110C-1 can carry bombs, it just needs a bit more runway than the C-4.

If we're worried about the runway required by the 110C-1, install the 601Aa, that offer a bit extra power down low, and same TO power that 601N was making.

Just trying to put things into context for range. The 110 was considered long range by some. It might have more than what is wanted for tactical support but the tactical support aircraft that is wanted in relatively static/slow moving battle may not the the tactical support aircraft that is ideal for fast moving battle campaign.

Trading a bomb load for fuel and vice-versa worked with the 110s. For European context, 110 was certainly a long-range A/C. If more bombs are required, a 110 that carries 4x 250 kg bombs might be easier to have produced than four 109s that carry one such bomb each, while also having a better range.
Granted, a more sleek design with a bomb bay would've been even better. Trick with the 110 was that it was actually there, even if it's fast-bomber role took some time to perfect.

 

[tomo pauk]

Design or describe a light bomber that will survive your anticipated conditions.

• Your engine (or engines) must be in production by 1939.
• Your weapons must be in production in 1939.
• Your aircraft must reach production in 1939.
• Your most serious victims will 1939 vintage armour, although we need to speculate on how you will cope with the heavier armour that will soon appear.
• Your protection is some combination of fighter level speed, defensive firepower and/or armour.
• Your aircraft should be able to operate from crude airfields close to the front line, allowing multiple missions per day. There is no need for long range.
• Your tactics minimise your exposure to ground fire, i.e., no vertical dive bombing. Maybe an extra crew can help with navigation and target spotting. Can you do radio communication with ground forces?

Supermarine's not-Henley?
Wing is from Spitfire, receiving the 'plugs' (as it was the case with Hurricane -> Henley) so now it is about 270-280 sq ft. New, a bit deeper fuselage with an useful bomb bay, cockpit for two (so the radio can be used more efficiently,a s well as to warn the pilot of impeding danger), cooling system is in the 'beard' configuration just in front of the bomb bay. 4 fuel tanks in the wings - a pair on the each side, each pair separated by the main spar. Wing can receive the Oerlikon (later Hispano) cannons + 4 .303s.

Should be both faster and longer-ranged than a bombed-up Hurricane.

Germans can do the similar design - talk the Ha 137 with fully retractable U/C, enclosed cockpit for 2 and a good engine in the nose?

 

[MarkS]

1939? The Martin Maryland and the Douglas DB-7/A-20 were the answer.

 

[Greyman]

I think anything but a fighter-bomber type would be too vulnerable.

 

[ThomasP]

No single-engine airframe at that time will be any more survivable than the Hurricane Mk IID was later, and the Mk IID needed fighter escort in any moderately to highly contested areas. There simply are no extant engines powerful enough to do the job in 1939. The airframe would either be too slow or too lightly armed - or both.

A twin-engine airframe might be doable. Something along the lines of a Peregrine/Merlin powered airframe the size of the Whirlwind? Or as already suggested, a design similar to the A-20? The French and Dutch had a couple of pre-war designs that might work.

 

[tomo pauk]

No single-engine airframe at that time will be any more survivable than the Hurricane Mk IID was later,

How bad in that regard would've a bombed-up Spitfire been?

There simply are no extant engines powerful enough to do the job in 1939.

What kind of power should've been needed?

 

[muskeg13]

1939? The Martin Maryland and the Douglas DB-7/A-20 were the answer.

Definitely. Both were about as good as it gets in 1939, but I'd install Wright R-2600 Cyclones from the start and have four .50s in the nose with none in the wings and no dorsal turret. They could The NA-40/B-25 was about a year too late to fit this timeline.

 

[ThomasP]

Hey tomo pauk,

re "How bad in that regard would've a bombed-up Spitfire been?"

If what you are looking for is a relatively lightweight fighter-bomber then the Spitfire, Hurricane, Bf109, etc would do. But from the OP it sounds like we are looking for a more capable attack aircraft. Yes?

re "What kind of power should've been needed?"

The Hurricane Mk II used the Merlin XX (as you know) and by the time the Mk IID and Mk IV were operational it had further increased boost of the 1942-43 period. So it had at least 1280 BHP available for TO and similar power or more for Vmax at low altitude. But its Vmax when carrying bombs or 40mm 'S' guns was still not much over about 250 mph, and maneuverability was limited. So IMO unescorted survivability does not meet the OP requirement.

In 1939-40 the maximum HP available for the Merlin was bout 1080 BHP at low level, so you won't get anything better than the Hurricane Mk IID performance at low altitude for sure, and almost certainly worse. The Spitfire or Bf109 fighter-bomber would be a bit faster than the Hurricane Mk IID/IV at altitude, but when loaded with bombs and/or cannon the ~1000 BHP engine power would probably make them just as vulnerable and in need of escort.

IMO you would need at least 1500 BHP for a single-engine attack aircraft to meet the OP requirements of load carrying ability and marginal survivability. I think you would need at least parity in speed at low altitude to the fighters of the time if there is to be the possibility of operating without escort and having reasonable attrition due to enemy fighters.

A twin-engine aircraft like the Whirlwind or A-20 (with low altitude rated engines of ~1000 BHP each) would at least have the power to carry a significant load and the low altitude speed to match the fighters of the time.

I think?

 

[tomo pauk]

If what you are looking for is a relatively lightweight fighter-bomber then the Spitfire, Hurricane, Bf109, etc would do. But from the OP it sounds like we are looking for a more capable attack aircraft. Yes?

Bf 109E was carrying a 250 kg/550 lb bomb once bomb rack was installed. Perhaps the early Spitfire, with it's bigger wing than what the 109 had, should be good for carrying three 250 lb bombs? We're at 75% of what the Battle or Blenheim was carrying.

The Hurricane Mk II used the Merlin XX (as you know) and by the time the Mk IID and Mk IV were operational it had further increased boost of the 1942-43 period. So it had at lest 1280 BHP available for TO and similar power or more for Vmax at low altitude. But its Vmax when carrying bombs or 40mm 'S' guns was still not much over about 250 mph, and maneuverability was limited. So IMO unescorted survivability does not meet the OP requirement.

In 1939-40 the maximum HP available for the Merlin was bout 1080 BHP at low level, so you won't get anything better than the Hurricane Mk IID performance at low altitude for sure, and almost certainly worse. The Spitfire or Bf109 fighter-bomber would be a bit faster than the Hurricane Mk IID/IV at altitude, but when loaded with bombs and/or cannon the ~1000 BHP engine power would probably make them just as vulnerable and in need of escort.

British can use the Merlin VIII (what Fulmar I used) - Lumsden says that these were being produced in 1939 as well as in 1940. Merlin X gives similar power down low, too; manufactured from 1938 per the same source.

IMO you would need at least 1500 BHP for a single-engine attack aircraft to meet the OP requirements of load carrying ability and marginal survivability. I think you would need at least parity in speed as low altitude to the fighters of the time if there is to be the possibility of operating without escort and having reasonable attrition due to enemy fighters.

In that case, Americans have it best, since Wright offers the 1600 HP R-2600, and P&W offers the 1400 HP R-2180A.

 

[ThomasP]

Hey tomo pauk,

re Merlin VIII & X

IIRC the Merlin VIII was rated at 1080 BHP for TO and 1030 BHP at ~6,000 ft in 1939. This went up quite a bit (1280 BHP+ on the deck with RAM) once it got some minor Mods and 100 grade fuel, but I do not know exactly when this happened. By early-1941 for sure, maybe before.

IIRC the Merlin X was was rated at 1040 BHP for TO and 1100 BHP at ~5,000 ft in early-1940 (I think). Again, this went up quite a bit (1260 BHP on the deck) with minor Mods and 100 grade fuel. Again, by early-1941 for sure, maybe before.


re the Bf109 as a fighter bomber

Do you have info on how fast the 1939-40 variant of the 109E was at low altitude and/or would have been with bombs?

 

[wuzak]

What about the Bristol Beaufighter?

If the Hercules aren't ready, then use Merlins or the Wright R-2600.

Add extra forward armour for attacking ground targets, could swap the 4 x 20m for 2 x 40mm Vickers S Guns later in the war,

 

[ThomasP]

IIRC the 40mm 'S' guns were not available yet in 1940, maybe mid-1941 at the earliest?