Fast bombers alternatives for 1939-40

[Shortround6]

Seems like the loss was 20 mph.
Henley not just used the more voluminous wing than the Hurricane, but there were no guns or ammo there, so it probably carried much greater tankage.

Henley had a two pitch prop.
Hurricane used 3-4 different props. The fixed pitch prop was supposed to be 22-24mph faster than the Henley but perhaps Hawker's factory figures area bit suspect in both cases?
Hawker factory says Hawker I with Rotal prop was good for 324mph?
Production Hurricanes were slower, I am guessing that the production Henley's would also be a bit slower.
I am trying to figure out the useful load for the Henley but is seems to be 2430lbs which is a bit skimpy for for a bomber with a two man crew.
Hurricane I is supposed to have a useful load of 1930lbs but that is for a late Hurricane I with protection fitted which the Henley did not have.
Eight .303s and ammo don't quite equal 500lbs of bombs but I don't know the weight of gun brackets, mounts and charging equipment.
What few sources I have seen say the Henley had 94 gal of fuel (Imp). Did the Henley use the same radio as the Hurricane or a larger, longer ranged (and heavier) radio?
If we want the Henley to do 940 miles we need a lot more than 94 gallons of fuel. The Fairey Fulmar carried 155 gal imp inside and yes it cruised lower in thicker air but it haas a range in the 700mile area.
I am not saying you could not do fit in more fuel with a some work but the numbers are not adding up.

 

[Steamed_Banana]

The BP P.94 was the turretless version of the Defiant.

I know

 

[yulzari]

I have been told that at least one of the Hurricane pilots of the BAFF in France preferred the fixed pitch propellor to the VP propellor as it gave a higher top speed at the cost of some climb. Conversely I note that the Defiants, last in the fighter queue to get CS propellors in the BoB, gained more in climb than top speed with the CS propellors.

It would seem that carrying a 500lb bomb load in a Hawker Henley could be better done under a Hurricane with the same engine. Faster and better able to defend itself after dropping the bombs. One must note that the Hurricane would be slower going to the target with external bombs than the Henley with internal bombs but faster going home and better able to defend itself going home. However the delivery should be less accurate from wing mounted external bombs in a shallow dive from a Hurricane than from a crutch in a steep dive of a Henley. There are many subtleties in comparing one candidate with another. I personally doubt if there is a use for a hand held rear gunner in a dive bomber. Fairey decided that on Battle experience that the extra speed of a smooth fuselage was more of a useful defence than the drag of a hand held gunner. Hence the Light Bomber, Fulmar and Firefly. Now with a powered turret like a Defiant or Roc that would be another matter. But then our OP Fast Bomber need not be a dive bomber.

Whilst a 1,000lb bomb load in a Blenheim was considered adequate in 1937 the Mosquito carried twice that internally far faster and it's jet replacement, the English Electric Canberra carried 8,000lb internally so what rates as an adequate bomb load is a variable chronologically and with available power.

We must, of course, remember that the OP is for a fast bomber for 1939/40 so we are looking at something beginning design and development in the mid 1930s with an internal bomb bay and 1938/9 available engines. My nomination would be the Martin Maryland. Just fast enough in service to be a problem for period fighters to intercept, good period bomb load and a successor upgrade might be to Wright 2600s as on the OTL Baltimore to eke it out through 1943 by which time we are looking to a 400+mph replacement.

 

[Shortround6]

I have been told that at least one of the Hurricane pilots of the BAFF in France preferred the fixed pitch propellor to the VP propellor as it gave a higher top speed at the cost of some climb. Conversely I note that the Defiants, last in the fighter queue to get CS propellors in the BoB, gained more in climb than top speed with the CS propellors.

We may be confusing VP props with CS props. Since the VP prop switched from take-off to high speed setting at around 140mph (give or take) the VP Prop in theory was no better at climb or top speed than the fixed pitch prop but that depended on the actual prop blades and there was a difference. On the other had a CS prop would give a significant advantage in climb to either the fixed pitch or the VP prop. A few VP props (a lot of German ones) were controllable by the pilot. Most were not and once shifted to the high speed position that was where they stayed until coming in to land. Merlin went from around 2850-3000rpm for take-off to around 2000-2200rpm for climb out after prop shift. Running at around 2/3 throttle really hurts climb.

Whilst a 1,000lb bomb load in a Blenheim was considered adequate in 1937 the Mosquito carried twice that internally far faster and

the 1000lb load was considered just fine for the Mosquito in the design phase and the very early production. I believe the first 10 bombers were built for the 1000lb load (four 250lb bombs) and early production was split between the fighter and photo-recon planes. Mosquito went to 2000lbs inside the bomb bay when they cut the fins on the 500lb bombs to make them fit. Didn't hurt that the Merlin engines had gained several hundred horsepower in the meantime either.

I personally doubt if there is a use for a hand held rear gunner in a dive bomber. Fairey decided that on Battle experience that the extra speed of a smooth fuselage was more of a useful defence than the drag of a hand held gunner. Hence the Light Bomber, Fulmar and Firefly.

I don't think it was Fairey, I think it was the air ministry? At any rate the Fairey Light Bomber was supposed to have a rear gun. Some Fulmars got rear guns, installed by the crews?, after they got tired of trying to use toilet paper or borrowed Lancaster submachine guns for defense. Battle aircraft had zero combat experience for most of the initial design period. Air Ministry placed order in June 1940 for the Firefly "off the drawing board" which sort of assumes there was something on the drawing board/s

 

[Steamed_Banana]

Single rear gun seems flimsy but I can tell you the ones on D3A Vals, SBDs (both the single and double gun mounts), Stukas, and many others actually did damage and shoot down some fighters and dissuade some more - though most seemed to just bore right in regardless, often ending up with a crippled plane as a result.

 

[Shortround6]

Single rear gun seems flimsy but I can tell you the ones on D3A Vals, SBDs (both the single and double gun mounts), Stukas, and many others actually did damage and shoot down some fighters and dissuade some more - though most seemed to just bore right in regardless, often ending up with a crippled plane as a result.

Maybe I am biased but there was a large difference in some of the guns. Japanese navy rear gun

About 98% identical to a WW I Lewis gun.
Not a bad gun but it fired at about 10 rounds per second. About 1/2 what a single Browning did and 1/4 what a twin Browning did (.303 or .30 cal)
Maybe the small guns didn't keep the planes from getting shot down but they made it more costly for the attackers.

 

[Steamed_Banana]

Maybe I am biased but there was a large difference in some of the guns. Japanese navy rear gun
View attachment 854179
About 98% identical to a WW I Lewis gun.
Not a bad gun but it fired at about 10 rounds per second. About 1/2 what a single Browning did and 1/4 what a twin Browning did (.303 or .30 cal)

And yet, that's one of the things that was notable in that Claringbould book about the Corsair operational histories - it looks like a fair number of Corsairs got basically shot down (crippled and then ditched or crash landed) by rear gunners on D3A Vals, at least two in one of the battles he gets into. Same thing happened to a lot of those AVG pilots in their first fights with Ki-21s, and with F4F pilots in the Solomon's and the various carrier battles etc. Many of the DAF pilots in the Med against Stukas too.

Maybe the small guns didn't keep the planes from getting shot down but they made it more costly for the attackers.

yeah I think this is right. A lot of fighter pilots just seemed to ignore them, sometimes to their peril. Sometimes they noticed their existence after taking damage or seeing one of their mates go down smoking.

 

[Howard Gibson]

Yes, this shows the problem.

Let's take the Spitfire and turn it into a high speed bomber, ala the Henley.
Slightly enlarge the tail (a small bit of drag)
lengthen the fuselage by about 4 ft to hold the rear seater (a little more drag)
Build stub wing to mount the existing wings to. Need more wing area for take-off but more drag
Build bomb bay of just two 250lbs or for two 500lbs bombs? 250lb bomb is 10.3in in diameter and the 500lb is 13in in diameter. Or a single 500lbs bomb with two 250lbs option? Henley did not have the single 500lb option. You do need clearance for for the racks and for the armorers to work so bomb bay is going to add more than 10.3 to 13 in the the height of the fuselage. More drag.

Watch out for the centre of mass. Reginald Mitchell placed the gas tanks at the aircraft centre of mass so that there were no trim changes as fuel was used up. Bombs need to be at the centre of mass too. Decent sized gas tanks did not fit into the Spitfire's wings. If you absolutely must have an internal bomb bay, you need to lengthen the centre section, leaving the gas tanks in the top, and the bombs in the bottom. Probably, you need to move the landing gear further out on the wings, which is not a bad thing. Can we have a back seater and still have a good handling aircraft, or do we need to move the engine forwards to correct?

How well to two-seat Spitfire_IXs fly?

 

[Howard Gibson]

Are we perhaps veering off towards a fighter bomber? That was the way things were going IOTL.

If you build a bomber in 1939 that somehow goes 350mph, I am going to mount guns on it and make a heavy fighter out of it. Think of Ju88s.

 

[tomo pauk]

If you build a bomber in 1939 that somehow goes 350mph, I am going to mount guns on it and make a heavy fighter out of it. Think of Ju88s.

Is there something in common with the 350 mph speed figure and a Ju 88 in 1939-40?

 

[Steamed_Banana]

A-20As went 350 mph and not too long after 1939

 

[Howard Gibson]

Is there something in common with the 350 mph speed figure and a Ju 88 in 1939-40?

1939 Ju88s did not do 350mph. Later ones did. They were fast, and the Luftwaffe made heavy fighter versions. Mosquitos also were converted to fighter bombers and heavy fighters.

 

[Shortround6]

We are mixing up aircraft.
Fighters were usually designed to hand about 8 Gs in service and different air forces had different amounts of overload designed in for safety. US used 50% for a 12 G ultimate load at failure. There were other loads like landing and side loads and yawing which are rarely discussed.
The Mosquito may have been designed for 5Gs in service.
Most American medium/light bombers were designed for 4 Gs, but the US very promptly started adding guns and turrets and all sorts of extra stuff. A heavily loaded B-25 could be operating at under 3 Gs and had rather sever flight restrictions until either fuel was burned off and/or bombs dropped.
Sticking a bunch of guns in the nose of a twin engine bomber does NOT make it a fighter.......................unless................................You are trying to shoot down enemy bombers which also are operating at much lower G levels.
Night fighters did not do 3-4 Gs turns or loops while chasing bombers (occasional exceptions).
Transports were built for even lower G loads, every pound of structure was a pound of cargo (passenger) not carried for money.

Most bombers did not have the control authority, controls could not be defected at high speed enough, to generate airframe breaking G loads. Some pilots were ham fisted enough to do it on occasion.

This is one reason you want to figure out if you high speed bomber is either a high speed bomber or a dive bomber. The dive bomber needs hundreds of pounds more structure to survive dive bombing on a regular basis (even training, or especially training?). If you are dealing with a 1939-40 engine how much weight do you want to devote to the structure?

 

[tomo pauk]

1939 Ju88s did not do 350mph. Later ones did.

(my bold)
The bolded part is the kicker.

They were fast, and the Luftwaffe made heavy fighter versions.

Day fighter versions of the Ju 88 were slower than the Bf 110 or the Beaufighter.

 

[Steamed_Banana]

What version of Ju 88 made 350 mph? Or are we talking about Ju 188?

 

[Howard Gibson]

We are mixing up aircraft.
Fighters were usually designed to hand about 8 Gs in service and different air forces had different amounts of overload designed in for safety. US used 50% for a 12 G ultimate load at failure. There were other loads like landing and side loads and yawing which are rarely discussed.
The Mosquito may have been designed for 5Gs in service.
Most American medium/light bombers were designed for 4 Gs, but the US very promptly started adding guns and turrets and all sorts of extra stuff. A heavily loaded B-25 could be operating at under 3 Gs and had rather sever flight restrictions until either fuel was burned off and/or bombs dropped.
Sticking a bunch of guns in the nose of a twin engine bomber does NOT make it a fighter.......................unless................................You are trying to shoot down enemy bombers which also are operating at much lower G levels.
Night fighters did not do 3-4 Gs turns or loops while chasing bombers (occasional exceptions).
Transports were built for even lower G loads, every pound of structure was a pound of cargo (passenger) not carried for money.

Most bombers did not have the control authority, controls could not be defected at high speed enough, to generate airframe breaking G loads. Some pilots were ham fisted enough to do it on occasion.

This is one reason you want to figure out if you high speed bomber is either a high speed bomber or a dive bomber. The dive bomber needs hundreds of pounds more structure to survive dive bombing on a regular basis (even training, or especially training?). If you are dealing with a 1939-40 engine how much weight do you want to devote to the structure?

From what I can tell, Bf110s were rated for 5Gs. According to Greg's Airplanes and Automobiles, Nakajima Ki.84s were rated only for 5Gs. Most bombers were absolutely unfit to become fighters, If your bomber is fast, it might not be all that difficult to reinforce the wings. Thicker sheet metal?

Using any heavy fighter in a dogfight was a good way to get shot down. The Ju88s became successful night fighters, as they were big enough to carry radar, and they were faster than the Lancasters and Halifaxes they were hunting.

 

[Steamed_Banana]

Ju 88Cs, though they did not make 350 mph, were actually fairly successful heavy fighters out in the maritime context particularly. They even shot down some P-38s.

 

[Howard Gibson]

What version of Ju 88 made 350 mph? Or are we talking about Ju 188?

The Ju88S-1 did 340mph at 26,250ft (8000m), and 379mph with GM1 injection turned on. This is all very late in the war.

 

[Shortround6]

The Ju88S-1 did 340mph at 26,250ft (8000m), and 379mph with GM1 injection turned on. This is all very late in the war.

Ah yes, the famous Ju88S-1.
I am really being to hate this plane as it shows up so much in discussions because of it's................drum roll...............SPEED.

But the Ju-88S-1 had two major problems.
1.The rear bomb bay was full of GM-1 tanks.
2. The front bomb bay was usually full of fuel.

This means that while the Ju-88S-1 could carry either two 500kg bombs or two 1000kg bombs they were on external racks and the speed with bombs on the racks is rarely given.
Ju-88 held 369 imperial gals of fuel with the forward bay empty and you are not going to get very far flying fast with that amount of fuel. About 545 miles at 328mph, kicking in the GM-1 is really going to suck up the fuel.
If you put bombs in the forward bay the usual load is 10 50kg bombs but if you could find them you could stuff 10 65kg bombs in. 250kg bombs won't fit, not even two.

 

[Howard Gibson]

Ah yes, the famous Ju88S-1.
I am really being to hate this plane as it shows up so much in discussions because of it's................drum roll...............SPEED.

But the Ju-88S-1 had two major problems.
1.The rear bomb bay was full of GM-1 tanks.
2. The front bomb bay was usually full of fuel.

I was going to respond to my own post about modifying Spitfires into fast bombers, but the point is valid here too.

Most WWII bombers were either mid-wing or high-wing. On a low wing monoplane like a Spitfire, the main spars pass through the fuselage. The fuel, ammunition, bombs and wings must all be located close to the aircraft's centre of mass. Among the advantages of low wing monoplanes is that the wings are located at a maximum distance from the pilot, where they obstruct a minimum of sky. This is one of the problems solved by the F4U Corsair's bent wings This was a feature of almost all WWII fighters. If the spars pass through the bomb bay, it splits it into two more more compartments, limiting the size of bomb you can carry. Think B17s versus B24s and Lancasters.

On Mosquito fighter bombers, the front of the bomb bay was occupied by the Hispano cannons, limiting the bomb load to two 500lb bombs, rather than the four carried by the bomber versions. Most of the photos of Ju88s that I have seen show bombs carried on external racks. Is the internal bomb bay absolutely necessary? A Spitfire bomber that carries its load externally, is smaller, and faster on the way home, after the enemy gets pissed off.