1935-45: alternative British bombers

[fastmongrel]

To be fair to the RAF what airforce in 1935 was planning on carrying anything bigger than a 500lb bomb internally.

 

[stona]

Dive bombers are not only required to do close support of the army. They can attack bridges and roads, railroads and marshaling yards, ports and ships, troops concentration, different vehicles - both soft-skinned and armored - that they meet in the target area. Dedicated forward/embedded officers are nor required for such tasks, even if they are necessary for the tasks of close air support to work well.

The RAF had developed its various light bombers for that. In 1939 the only really relevant type was the Fairey Battle. There were 160 of them in France as part of the Advanced Air Striking Force two days before Britain and France declared war on Germany.

Dive bombers were seen by the RAF as aircraft for close air support and there were deep rooted doctrinal reasons why there was fierce resistance to this sort of operation within the Air Ministry and RAF. They would not be overcome until well into the war.

A feasible 'what if' might be the development of a decent dive bomber for the Admiralty, to be used by the FAA in anti-shipping operations.

 

[Shortround6]

Seems like someone reported it partially wrong?

Perhaps.
From wiki so usual cautions.
from the entry on the Beaufort.

"The basic structure, although similar to the Blenheim, introduced refinements such as the use of high-strength light alloy forgings and extrusions in place of high-tensile steel plates and angles; as a result the structure was lighter than that of the Blenheim.[11][N 3] "
The reference is to Bristol aircraft since 1910 by C.H. Barnes, the N3 note says (unattributed) "The added weight of the Beaufort was due to the additional equipment and crew accommodation, plus the heavier engines. "

Stronger it certainly was at Beufort, both when looking at tare weight of the whole aircraft, max permissible weight, ability to morph into Beaufighter without much of calamity, and the G load.
Lighter wing - I'd say no. Beaufort weighted - tare weight - between 12760 and 14000 lbs, Blenheim started at 8077 lbs, went to ~ 9250-9800 lbs to Mk.IV, and 10650 lbs on Mk.V (that also had a 3 ft longer nose).

You are overlooking all the other changes, including "The Vickers main undercarriage units were similar to but larger than those of the Blenheim and used hydraulic retraction, with a cartridge operated emergency lowering system" Blenheim did use hydraulic retraction but you do need larger, heavier landing gear for a 21,000lb airplane than you do for a 14,000lb airplane. The wing could easily have been lighter on the Beaufort, with the much larger fuselage, increased equipement, heavier engines, props and landing gear these could all have out weighed whatever weight saving there was in the wing.

Blenheim was already too big for it's engines, speed went quickly down from respectable 286 mph for the Mk.I to 260-266 for the Mk.IV. Being slower and bigger makes it easier to shot down both for enemy fighters and AAA.

The Blenheim got some rather questionable "improvements" during it's career, the 260-266mph version looked like this

The fuel dump tubes didn't help and you could probably pick up some speed by getting rid of the under chin reward firing gun mount. Increased drag slowed the plane down as much or more than the weight alone. Top turret is always a question. Since it was semi-retractable, one always wonders if the speed quoted is with the turret up or down. A bit of time spent on cleaning up some of the more obvious drag problems might have paid dividends (or gotten the plane a lot closer to the 280mph mark)

 

[tomo pauk]

Perhaps.
From wiki so usual cautions.
from the entry on the Beaufort.

"The basic structure, although similar to the Blenheim, introduced refinements such as the use of high-strength light alloy forgings and extrusions in place of high-tensile steel plates and angles; as a result the structure was lighter than that of the Blenheim.[11][N 3] "
The reference is to Bristol aircraft since 1910 by C.H. Barnes, the N3 note says (unattributed) "The added weight of the Beaufort was due to the additional equipment and crew accommodation, plus the heavier engines. "

Also from Wikipedia, Blenheim entry, per Moyes' book about Blemheim:

"The fuselage of the Blenheim employed a light-alloy monocoque structure using open-section stringers, and was constructed in three sections.[17] The wing is also built in three sections, the center-section of which is bolted and rivetted to the fuselage. The outer wing sections are tapered in chord and thickness.[17] Extensive use of Alclad sheeting is made in elements such as the ribs, skin, flaps, and web reinforcement of the spars. The tail unit is of a cantilever monoplane style, using an all-metal tailplane and fin while the aerodynamically-balanced rudder and elevators use a metal frame covered with fabric.[17] "

In other words, no mention of steels on Blenheim.

You are overlooking all the other changes, including "The Vickers main undercarriage units were similar to but larger than those of the Blenheim and used hydraulic retraction, with a cartridge operated emergency lowering system" Blenheim did use hydraulic retraction but you do need larger, heavier landing gear for a 21,000lb airplane than you do for a 14,000lb airplane. The wing could easily have been lighter on the Beaufort, with the much larger fuselage, increased equipement, heavier engines, props and landing gear these could all have out weighed whatever weight saving there was in the wing.

Dry weight of engines was 2x300= 600 lbs more on Beaufort, add perhaps 2x150= 300 lbs for bigger oil system, bearings and prop? Add the 'fittings' for an additional crew member, heavier landing gear, bits and pieces for another 1000 lbs, and it still comes way short of the 3500-4000 lbs weight difference for tare weights.
My take is that someone writing a book drink a bit of Cool Aid so the Beaufort could came in as being as a bleeding-edge technolgy bomber, vs. the backwards tech Blenheim?

The Blenheim got some rather questionable "improvements" during it's career, the 260-266mph version looked like this
The fuel dump tubes didn't help and you could probably pick up some speed by getting rid of the under chin reward firing gun mount. Increased drag slowed the plane down as much or more than the weight alone. Top turret is always a question. Since it was semi-retractable, one always wonders if the speed quoted is with the turret up or down. A bit of time spent on cleaning up some of the more obvious drag problems might have paid dividends (or gotten the plane a lot closer to the 280mph mark)

We can indeed do without these appendices. Still leaves the RAF with a 280 mph bomber that needs to do level bombing, that will be of questionable utility when Germans' fighters and especially their Flak can be expected, even if it could provide a very useful service over the ocean.
In order to actually extend Belheim's utility, I'd try to re-engine it with Merlin for tasks over Europe, and to modify it into a torpedo/dive bomber for tasks that involve enemy ships as targets, with Mercury engines or something else.

 

[Shortround6]

For RAF, their gear is the topic here.
Dive bombers are not only required to do close support of the army. They can attack bridges and roads, railroads and marshaling yards, ports and ships, troops concentration, different vehicles - both soft-skinned and armored - that they meet in the target area. Dedicated forward/embedded officers are nor required for such tasks, even if they are necessary for the tasks of close air support to work well.

can attack is not the same as needed to attack. The need for a dive bomber to perform those missions is subject to question. Quite a few air forces had either no dive bombers or very few until the German Blitzkrieg in Poland and France and the accompanying newsreel footage. At which point it was a case of the "the Germans have them so we need them too". But the focus was the overall effect (exaggerated by propaganda) and not how it was achieved (tactics, doctrine, training) and the assumption that by having a similar airplane the other nations would automatically get similar effects.
and the effects the germans got was partially the result of the poor AAA of the armies/nations they were attacking. Some accounts claim the Germans had up to 303 AA guns defending the bridges over the Meuse, The Germans rarely, if ever, had to face such concentrated AA. Not to mention the German fighters providing protection.
You could have given the British 100 Ju 87s to use in the attacks and the results would not have been much different without changing the tactics, escorts and other factors.

A dive bomber that can carry 2-3-4 500lb bombs will carry a 1000 lb bomb far better than a bomber designed to carry just one such bomb. Something like the Italian Ro.57, or a pre-Whirlwind with two Mercuries, or something like the Fw 187 with British engines.

Conversely, we can come out with a much smaller dive bomber to carry a 500 lb bomb. Talk something size of Spitfire, Re.2000, P-36/-40 or Gloster F.5/35. Or, have Hurricane carrying two bombs.

If you are carrying four 500lbs you have light bomber that can dive, It might be single engine something like the Avenger but it won't be a small airplane if you expect any range.


The Ro 57 used a single bomb crutch under the fuselage for up to a 500kg bomb.

In the 30s a bomber, even a dive bomber or tactical bomber, was expected to have certain amount of range. Having bases 50-100 miles from the areas it was supposed to bomb may not have been regarded as very likely? Actual war with thousands of planes produced and manned (include ground crew) and hundreds of airfields built is a very different operational environment than what was envisioned leading up to WW II.

 

[Shortround6]

In other words, no mention of steels on Blenheim.

Extensive use of Alclad sheeting is made in elements such as the ribs, skin, flaps, and web reinforcement of the spars.

Nothing saying steel wasn't used in the Spars or spar construction or attachment points. In fact the top and bottom plates of the spars were high tensile steel flanges with an "alclad" single plate web between them. The question comes in with how many elements were changed between the two wings. And/or how many parts/elements became single pieces instead of built up assemblies.

 

[tomo pauk]

can attack is not the same as needed to attack. The need for a dive bomber to perform those missions is subject to question. Quite a few air forces had either no dive bombers or very few until the German Blitzkrieg in Poland and France and the accompanying newsreel footage. At which point it was a case of the "the Germans have them so we need them too". But the focus was the overall effect (exaggerated by propaganda) and not how it was achieved (tactics, doctrine, training) and the assumption that by having a similar airplane the other nations would automatically get similar effects.
and the effects the germans got was partially the result of the poor AAA of the armies/nations they were attacking. Some accounts claim the Germans had up to 303 AA guns defending the bridges over the Meuse, The Germans rarely, if ever, had to face such concentrated AA. Not to mention the German fighters providing protection.
You could have given the British 100 Ju 87s to use in the attacks and the results would not have been much different without changing the tactics, escorts and other factors.

Anything that enemy uses falls under 'needed to attack' category.
RAF/AM can go see US dive bombers accurately planting the bombs on targets by early 1930s, then compare the accuracy of their bombers of similar size flying at 15000 ft and draw conclusions. 'Dive bomber' category is not same as 'slow bomber', a dive bomber sized of Re 2002 (used as dive bomber, up to 680 kg bomb) is not slow-as-mud and big Ju 87 or Battle.
I do agree that escort need to be provided, but upping chances for bomber pilots, by sitting them into more elusive targets, is not just to make their escape but also for them to accomplish their missions is a worthwhile thing to do.

If you are carrying four 500lbs you have light bomber that can dive, It might be single engine something like the Avenger but it won't be a small airplane if you expect any range.

It will not be a small plane. On the other hand, it does not need to be bigger than Me 210.
The Re.2002 carried 400 kg of fuel - 147 US gals.

The Ro 57 used a single bomb crutch under the fuselage for up to a 500kg bomb.

1000 kg bomb.

In the 30s a bomber, even a dive bomber or tactical bomber, was expected to have certain amount of range. Having bases 50-100 miles from the areas it was supposed to bomb may not have been regarded as very likely? Actual war with thousands of planes produced and manned (include ground crew) and hundreds of airfields built is a very different operational environment than what was envisioned leading up to WW II.

Again Ro.57 - engines not better than Mercury, 700 kg of fuel, 1000 kg bomb (more than twice of Blenheim), almost half of the wing of Blenheim.
More later

 

[nuuumannn]

Please note that nobody is trying to leave RAF speachless with regard to torpedo or 'ordinary' bombing, or night fighting capability. Early start for Mosquito is suggested instead (that can cover a lot just by itself), Hampdens (not just) for torpedo bombing instead of the stillborn Botha, improved Blenheim etc.

BTW - when (if ever?) is the right time and approach for the RAF to start requesting bespoke dive-bombers?

A lot of wishful thinking going on here, Tomo. There is no "early start for the Mosquito". The prototype first flew in November 1940 - you are not going to get it any earlier. It was first suggested on paper in September 1939 and it was built in a shed on a country estate in secret. De Havilland was also not geared up for mass production at that time and by the end of 1941, following the issuing of a production contract in March 1940, DH Hatfield had produced 20 Mosquitoes, a couple of those were prototypes and there were the four airframes built at Salisbury Hall, including the prototype.

The Hampden (and Wellington) were converted for carrying torpedoes because of the shortage of modern RAF torpedo carrying types, most notably delays with the Beaufort, and the Botha was built initially as a the loser to the Beaufort specification 10/36, so, no Beaufort, no Botha, that is, unless Blackburn is the only entrant to the specification, which again brings your theory into question - Bristol would have no doubt produced an aircraft to the spec for a new torpedo bomber, which would have been the Beaufort. Nevertheless, Blackburn should have been directed to channel its resources elsewhere sooner rather than putting the Botha into production! On that we can agree.

Again, no point in beefing up the Blenheim - to what end and when does this begin? Before the war? The Blenheim was designed by Barnwell who died and so design within Bristol on the Beaufort and Beaufighter was the work of Frise, so why redo the Blenheim at that time? After the war begins? Then what? Blenheim production is disrupted and delayed because of the work needed to redo the aircraft.

Firstly you need more powerful engines, let's say, Hercules, which means beefing up the wing and nacelle structure, then the undercarriage as well, because presumably you want to carry heavier loads, so the overall structure of the aircraft probably needs strengthening, which probably means a different fuselage design, which will be dictated by what you want it to do. Then what? By 1941/42 when you've settled on a design and got it into production, the Mosquito is coming on line in numbers and the RAF is receiving B-25s and Bostons under Lend Lease, which replaced the Blenheim in the medium bomber role anyway... Just doesn't seem worth the effort in hindsight, especially when before the war, Frise's Beaufighter was pretty much the aircraft that an improved Blenheim would have become. Perhaps Bristol should have shut down Blenheim production and built more Beaufighters.

As for dive bombers, the P.4/34 specification that produced the aircraft that the Fulmar was modelled on specified dive bombing - in 1934, and its competitor was the Hawker Henley. That the RAF didn't pursue the idea and the Henley ended up as yet another target tug was obtuse thinking at high levels within the RAF and Air Ministry.

Specification called that the torpedo is also to be carried, so I'd say it was designed in, rather than it was an accident, even partially.

Actually no, it didn't. B.9/32, to which the Hampden and the Wellington were built did not specify carrying torpedoes - odd then, that both were specifically modified to do so. The basic design for the HP.52 came as much from a twin-engined floatplane torpedo carrier being investigated by the Swedish government, but was never built, but its torpedo was to be slung between the twin floats, so, yeah, you are partially right.

 

[tomo pauk]

A lot of wishful thinking going on here, Tomo. There is no "early start for the Mosquito". The prototype first flew in November 1940 - you are not going to get it any earlier. It was first suggested on paper in September 1939 and it was built in a shed on a country estate in secret. De Havilland was also not geared up for mass production at that time and by the end of 1941, following the issuing of a production contract in March 1940, DH Hatfield had produced 20 Mosquitoes, a couple of those were prototypes and there were the four airframes built at Salisbury Hall, including the prototype.

D-H was writing the letters to the Air Ministry about the virtues of a gun-less bomber that is made predominantly from wood materials in July of 1938. Perhaps we can't speed up Mosquito program by those 13 months, but might by half of that.

The Hampden (and Wellington) were converted for carrying torpedoes because of the shortage of modern RAF torpedo carrying types, most notably delays with the Beaufort, and the Botha was built initially as a the loser to the Beaufort specification 10/36, so, no Beaufort, no Botha, that is, unless Blackburn is the only entrant to the specification, which again brings your theory into question - Bristol would have no doubt produced an aircraft to the spec for a new torpedo bomber, which would have been the Beaufort. Nevertheless, Blackburn should have been directed to channel its resources elsewhere sooner rather than putting the Botha into production! On that we can agree.

Good - no Botha, so material and human resources of both company and government are used to make something useful.

Again, no point in beefing up the Blenheim - to what end and when does this begin? Before the war? The Blenheim was designed by Barnwell who died and so design within Bristol on the Beaufort and Beaufighter was the work of Frise, so why redo the Blenheim at that time? After the war begins? Then what? Blenheim production is disrupted and delayed because of the work needed to redo the aircraft.

Frise can make a clean-sheet 2-engined fighter for 1940 - not as small as Whirlwind, but certainly not as big as the Douglas DB7 or A-20 bomber.
I'm not suggesting that we turn Blenheim into a war-winner, but some nip & tuck might improve it's usability and survivability. RAF needed better Blenheims more than it needed vast number of those.

Firstly you need more powerful engines, let's say, Hercules, which means beefing up the wing and nacelle structure, then the undercarriage as well, because presumably you want to carry heavier loads, so the overall structure of the aircraft probably needs strengthening, which probably means a different fuselage design, which will be dictated by what you want it to do. Then what? By 1941/42 when you've settled on a design and got it into production, the Mosquito is coming on line in numbers and the RAF is receiving B-25s and Bostons under Lend Lease, which replaced the Blenheim in the medium bomber role anyway... Just doesn't seem worth the effort in hindsight, especially when before the war, Frise's Beaufighter was pretty much the aircraft that an improved Blenheim would have become. Perhaps Bristol should have shut down Blenheim production and built more Beaufighters.

No, not Hercules for the Blenheim. Too heavy. Go with Merlins (cooling system does not need to be hanged in front of main spar) or/and Taurus, and with low-level Mercuries for naval attack/torpedo bombing.
There was no Beaufighter before war, bar prototype. Better Blenheim is needed for 1939-41 - until there is enough of other 2-engined stuff to completely replace it by 1942.

Actually no, it didn't. B.9/32, to which the Hampden and the Wellington were built did not specify carrying torpedoes - odd then, that both were specifically modified to do so. The basic design for the HP.52 came as much from a twin-engined floatplane torpedo carrier being investigated by the Swedish government, but was never built, but its torpedo was to be slung between the twin floats, so, yeah, you are partially right.

Thank you.

 

[Admiral Beez]

Starting with the 1935 beginning period of this thread, and putting aside that there were very few aircraft still active into the Second World War, what can we do to keep the Heyford relevant past its 1941 retirement? Perhaps as a rough field, STOL bomber over Burma? Did any Kestrel have variable pitch, three or four blade props?

 

[Shortround6]

Anything that enemy uses falls under 'needed to attack' category.

Badly stated by me or doesn't translate well.
"can attack is not the same as needed to attack." was in reference to the type of planes used for the attack. AS in Plane A is good at attacking targets R,S and T and can attack targets X, Y and Z but it's special attributes are not needed to attack X, Y and Z.

Dive bombers can attack rail road yards or troop/supply columns on roads. But they are not needed for such attacks, The targets are large and pin point accuracy is not needed. Infact a low level bomber with numerous small bombs might be preferred for such targets.

RAF/AM can go see US dive bombers accurately planting the bombs on targets by early 1930s, then compare the accuracy of their bombers of similar size flying at 15000 ft and draw conclusions. 'Dive bomber' category is not same as 'slow bomber', a dive bomber sized of Re 2002 (used as dive bomber, up to 680 kg bomb) is not slow-as-mud and big Ju 87 or Battle.
I do agree that escort need to be provided, but upping chances for bomber pilots, by sitting them into more elusive targets, is not just to make their escape but also for them to accomplish their missions is a worthwhile thing to do.

A dive bomber, to be accurate, needs to dive at a steep angle at a relatively slow speed (what the dive brakes are for) to give the pilot time to aim and correct aim. Many dive bombers started theri dives between 6-12,000ft meaning they can't sneak up on a target, no matter what their speed, like a low altitude bomber can. Loading a fighter sized plane with a heavy bomb load means they can't maneuver very well and are going to have difficulty avoiding/evading the defending fighters unless they drop their bombs, at which point the defending fighters have succeeded (at least for a few hours) even if they don't shoot a single bomber down. By the way, what was the range of the R2 2002 when toting 680kg of bombs?
The Douglas SBD has some rather astonishing bomb loads listed but unless the target was practically visible from the Carrier's bridge (exaggeration) they weren't going to carry that bomb load in an attack, The SBD traded fuel for bomb load, as did many other dive bombers. This assumes the SBD could even get off the carrier deck with the listed 2250lb load. Long paved runway on an Island might be possible.
When the enemy invades your country and is marching/driving to your existing airfields then sticking large bombs on short ranged fighters makes a certain amount of sense.

It will not be a small plane. On the other hand, it does not need to be bigger than Me 210.
The Re.2002 carried 400 kg of fuel - 147 US gals.

A Me 210 weighs as much empty as an early P-38 did loaded but clean. Not sure the 210 could carry 4 250kg bombs, it may have been volume limited.
Can the Re 2002 carry full internal fuel while carrying max (or near max ) bomb load

1000 kg bomb.
Again Ro.57 - engines not better than Mercury, 700 kg of fuel, 1000 kg bomb (more than twice of Blenheim), almost half of the wing of BlenheimMore later

A lot of controversy/varying sources on this one but basically we have a plane about the size of a Whirlwind, with crappier engines carrying double the bomb load and more fuel at the same time?

Most sources say the 20mm guns were MG 151s but the illustration you provided says 60 rounds per gun??? (My Italian stops at buongiorno

weights don't add up for most published books. with 590 kg of fuel the plane only has 415kg of payload left before hitting max weight but published figures may be for the interceptro version and and higher gross weight was allowed for the Dive bomber?

 

[Graeme]

In fact, I have a copy of that book sitting next to me as I write this - well worth getting a hold of.

Don't have it, but does it mention the Boulton Paul P.79 and in particular the "revolution-ary" bomb dispenser?
Very impressive for the '30s.

This is from an old PROFILE magazine...

 

[Graeme]

 

[tomo pauk]

Badly stated by me or doesn't translate well.
"can attack is not the same as needed to attack." was in reference to the type of planes used for the attack. AS in Plane A is good at attacking targets R,S and T and can attack targets X, Y and Z but it's special attributes are not needed to attack X, Y and Z.

Dive bombers can attack rail road yards or troop/supply columns on roads. But they are not needed for such attacks, The targets are large and pin point accuracy is not needed. Infact a low level bomber with numerous small bombs might be preferred for such targets.

A supply column on the road or a passing train can also be attacked with a dive bomber that drops several medium-sized bombs, eg. 4 x 250 lbs. I didn't suggested that RAF attacks German factories eith dive

A dive bomber, to be accurate, needs to dive at a steep angle at a relatively slow speed (what the dive brakes are for) to give the pilot time to aim and correct aim. Many dive bombers started theri dives between 6-12,000ft meaning they can't sneak up on a target, no matter what their speed, like a low altitude bomber can. Loading a fighter sized plane with a heavy bomb load means they can't maneuver very well and are going to have difficulty avoiding/evading the defending fighters unless they drop their bombs, at which point the defending fighters have succeeded (at least for a few hours) even if they don't shoot a single bomber down. By the way, what was the range of the R2 2002 when toting 680kg of bombs?
The Douglas SBD has some rather astonishing bomb loads listed but unless the target was practically visible from the Carrier's bridge (exaggeration) they weren't going to carry that bomb load in an attack, The SBD traded fuel for bomb load, as did many other dive bombers. This assumes the SBD could even get off the carrier deck with the listed 2250lb load. Long paved runway on an Island might be possible.
When the enemy invades your country and is marching/driving to your existing airfields then sticking large bombs on short ranged fighters makes a certain amount of sense.
Can the Re 2002 carry full internal fuel while carrying max (or near max ) bomb load

Training manual for the P-40 dive-bombing - that was not a dive bomber of any fame or even of note - calls to level-out at 4500 ft above the target, then roll over so the dive can be commenced. So pilots can certainly open their throttles when at 500 ft, fast climb to 4500-5000 ft and commence the dive from there. Dive angle recommended close to 70 deg, but not more. Pull out at between 2000 ft (recommended) and 1000 ft.
Range figures for the Re.2002 with the huge bomb - don't have any at the moment. The P-40 with 150 gal internal fuel only and a 500 lb bomb was pretty short ranged if it cruised on 250 mph or more and with allowance for 30 gal (warm up, take off and climb to 9000 ft). On 'bomber speeds' cruise (210-220 mph), it did 690 miles of range. I have o data for P-40 that carries both drop tanks and bombs.
The Re. 2002 will not get any better results even with 250 kg bomb, let alone with much bigger bombs. On the other hand, and as mentioned above, aircraft rated for bigger loads can trade fuel load for bomb load and vice versa.

A lot of controversy/varying sources on this one but basically we have a plane about the size of a Whirlwind, with crappier engines carrying double the bomb load and more fuel at the same time?
Most sources say the 20mm guns were MG 151s but the illustration you provided says 60 rounds per gun??? (My Italian stops at buongiorno

If cannons were installed, their installation necessitated the reduction of the size of nose fuel tank. With HMGs and their ammo, smaller fuel tank, and cannons installed, the nose was a tight place in such a small aircraft. Engines on the Ro.57 were indeed crappier than what Whirly had, but complete powerplants were lighter, and gun armament was very light, the 20mm guns were rarely (if ever past a prototype or two?) carried.
Going with what Ro.57 did with the laughable engines and tiny wing, and how the Blenheim grew in weight (both tare and max TO, last one by 4500 lbs Mk.V vs. Mk.I), a torpedo-toting Blenheim or/and a Blenheim carrying a 1000 bomb seems like a missed opportunity.
Performance figures on the picture are for the Ro.57 with just HMGs - no bombs or cannons, as noted at the bottom of the picture.

weights don't add up for most published books. with 590 kg of fuel the plane only has 415kg of payload left before hitting max weight but published figures may be for the interceptro version and and higher gross weight was allowed for the Dive bomber?

What I've posted is found on the official pamphlet issued by the General Staff of the Italian Royal Airforce (Stato Maggiore R. Aeronautica), can be downloaded eg. from here.
On the other hand: take-off weight with a 500 kg bomb, no cannons, and 648 kg of fuel was 4990 kg - our valiant Ro.57 will not be carrying in one go both max fuel, 1000 kg bomb and 20 mm cannons. Or even the 1000 kg bomb and max fuel without the cannons?
Manual for the Ro.57: link[/QUOTE]

 

[Shortround6]

A supply column on the road or a passing train can also be attacked with a dive bomber that drops several medium-sized bombs, eg. 4 x 250 lbs. I didn't suggested that RAF attacks German factories eith dive

A lot of this depends on when in 1935-1945.
I didn't say you wanted to attack factories with dive bombers, and the British had plenty of bombers for attacking factories anyway (or thought they did).
The Americans and British certainly used many fighters as fighter bombers using diving attacks and in the last years of the war had enough that they could send them out to attack targets of opportunity (passing trains) rather than specific pre-planned targets. In the Early part of the war? Not so much.
You also had the change in engines. A P-40 had 1325hp for take-off in 1942 and the Ns (the big bomber variant) had 1200 with perhaps more in reserve if they used WEP to get off the runway. The Hawker Henley used a Merlin II (not III) engine for the production versions and while the prototype flew with a Hamilton standard propeller the production planes git two pitch de Havillands. It carried 1/2 the bomb load you suggest and yes the Hurricane would up carrying more but not until the Merlin XX engine was fitted.

Training manual for the P-40 dive-bombing - that was not a dive bomber of any fame or even of note - calls to level-out at 4500 ft above the target, then roll over so the dive can be commenced. So pilots can certainly open their throttles when at 500 ft, fast climb to 4500-5000 ft and commence the dive from there. Dive angle recommended close to 70 deg, but not more. Pull out at between 2000 ft (recommended) and 1000 ft.

Ok.................Let's see, take 1 1/2 to 2 minutes to climb to 4500ft from 500ft ending at under 200mph forward speed. Re-acquire the target, roll over (Inverted) establish 70 degree dive (pull though 110 degrees) line up target in sight (or gum stuck to windscreen) and release bomb all in a matter of seconds so you can pull out at just under 2000ft???
Accuracy (the whole point of dive-bombing ) is???????? ANd while the P-40s are doing their fast climb to 5000ft within 4-8 miles of the target the AA guns are getting in another hand of cards?

You were an AA gunner, if you were tasked with defending a Bridge and saw bunch of aircraft doing this sort of maneuver within sight of the bridge what would your crew have been doing?
Lots of planes can drop bombs in a dive and get better accuracy than level bombing or low level fast bombing. But true dive bombers (You asked for a Bespoke dive bomber) used the longer dive and dive brakes to allow for a certain amount of time to line up the target and even to adjust for wind drift. That is where the test results of high accuracy came from. Test range accuracy also had nobody shooting at the planes so yes, in a lot of cases using the 1930s/1940 (battle of France) textbook approach and dive could lead to high losses.
The early dive bombers were conceived with the idea of placing a large bomb on a high value/small target. Like ships, bridges, strong points/bunkers. Hits 50-100yds away were worthless.
Hits with small bombs were worthless (damage ship, not sink it) as engine power increased and the dive bombers shift to 1000lb bombs instead of 500lb or larger than 1000lbs then rigging them for multiple bombs for alternative targets becomes more doable.

Italian planes will come later but the principles are already covered.
Thanks for the info on the Italian planes it is scarce in english.

 

[Admiral Beez]

View attachment 605946

It does look every tighter than the other dustbin type turrets.

 

[tomo pauk]

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The Americans and British certainly used many fighters as fighter bombers using diving attacks and in the last years of the war had enough that they could send them out to attack targets of opportunity (passing trains) rather than specific pre-planned targets. In the Early part of the war? Not so much.
You also had the change in engines. A P-40 had 1325hp for take-off in 1942 and the Ns (the big bomber variant) had 1200 with perhaps more in reserve if they used WEP to get off the runway. The Hawker Henley used a Merlin II (not III) engine for the production versions and while the prototype flew with a Hamilton standard propeller the production planes git two pitch de Havillands. It carried 1/2 the bomb load you suggest and yes the Hurricane would up carrying more but not until the Merlin XX engine was fitted.

For the RAF to consider fighter-bombers would've required a major change in doctrine.
The P-40N was capable taking off with 2x225 gal drop tanks (2640 lbs of fuel, plus whatever the drop tanks and sway braces weighted) on 1200 HP - not some power surplus vs. Re2002 with 1150 HP engine. Granted, we can't dismiss the possiblity of the P-40s over-boosting their engines for take off, even if that's just one minute.
SBD-1 was supposed to take off from a carrier with 1600 lb bomb and 180 gals of fuel in s-s tanks, just above 1000 ft (feet, not yd) was needed without the head wind, and 470 ft with 25 kt head wind. All on 1000 HP for take off.

Granted, the really big bombs on aircraft with modest power do introduce a number of shortcomings, but it can be done.

Ok.................Let's see, take 1 1/2 to 2 minutes to climb to 4500ft from 500ft ending at under 200mph forward speed. Re-acquire the target, roll over (Inverted) establish 70 degree dive (pull though 110 degrees) line up target in sight (or gum stuck to windscreen) and release bomb all in a matter of seconds so you can pull out at just under 2000ft???
Accuracy (the whole point of dive-bombing ) is???????? ANd while the P-40s are doing their fast climb to 5000ft within 4-8 miles of the target the AA guns are getting in another hand of cards?

You were an AA gunner, if you were tasked with defending a Bridge and saw bunch of aircraft doing this sort of maneuver within sight of the bridge what would your crew have been doing?

We gunners love our targets flying without change of speed, altitude or course (altitude preferably not being to small or too high, speed we want as low as possible). A bomber that is flying straight and level, and then tryies to climb while trading airspeed for altitude is already not our favorite - it changes 2 of the 3 things listed. Once it is 4500 ft above the ground it is almost over the practical ceiling of the 20mm guns that was 90% of what Germans had in 1939 and on WRT to the light Flak (37-40mm can get it there, so can the 88s) When it starts rolling into the turn and then into dive means changing course, speed and altitude in quick succession - we fire at it, but we don't like it since it is not flying steady like it is supossed to Once in dive, gunners can hit it well if it dives directly towards them, not that easily if it dives towards something hundreds meters away from.
Dive bombers surviving until the pull-out and running for their lives at tree top and at max speed are pretty much safe from the AA that is defending the target they just visited, unlike the level bombers that are carrying on at altitudes close to the altitudes they arrived. They also leave less of favorable angles for pursuing fighters to tackle them.
The level bombers trying to bomb from altitudes that put them above the ceiling of 20mm will most likely be too inaccurate to hit the small target.

Lots of planes can drop bombs in a dive and get better accuracy than level bombing or low level fast bombing. But true dive bombers (You asked for a Bespoke dive bomber) used the longer dive and dive brakes to allow for a certain amount of time to line up the target and even to adjust for wind drift. That is where the test results of high accuracy came from. Test range accuracy also had nobody shooting at the planes so yes, in a lot of cases using the 1930s/1940 (battle of France) textbook approach and dive could lead to high losses.

My bespoke dive bomber for early war for RAF would've certainly have dive brakes (although the reinforced undercarriage is tempting, so it can be used in dive as impromptu dive brake), hopefully Merlins, size no bigger than Gloster F.9/37 (if 2-engined), bomb bay for one 2000 lb bomb (or more smaller bombs; bomb bay being something like the bomb bay on the Avenger or Helldiver), crew of 2 in tandem.

 

[Shortround6]

For the RAF to consider fighter-bombers would've required a major change in doctrine.
The P-40N was capable taking off with 2x225 gal drop tanks (2640 lbs of fuel, plus whatever the drop tanks and sway braces weighted) on 1200 HP - not some power surplus vs. Re2002 with 1150 HP engine. Granted, we can't dismiss the possiblity of the P-40s over-boosting their engines for take off, even if that's just one minute.
SBD-1 was supposed to take off from a carrier with 1600 lb bomb and 180 gals of fuel in s-s tanks, just above 1000 ft (feet, not yd) was needed without the head wind, and 470 ft with 25 kt head wind. All on 1000 HP for take off.

The take-off distances for the P-40N using 1200hp and not specifying either temperature or runway surface are:

1-170 US gal tank, 2500ft.
2-170 US gal tanks, 3800ft
2-225 US gal tanks, 4500ft.
about 15 degrees of flap was used, When using these tanks ammunition was seldom carried, These were ferry tanks. Take-off speed was 135mph (doesn't say for which tank set up)

P-40N was supposed to take-off, zero wind/sea level, hard surface, in 950ft at 7800lbs and need 1100ft at 8400lbs.
2 problems.
1. A P-40N-25 went about 8350lbs with full internal fuel and ammo. Not even the 52 gallon drop tank.
The distances immediately above are for 0 degrees C (32 degrees F) and 9% needs to be added for every 10 degrees C(20 degrees F) above that temperature. Or about 27-30% for tropical (southern Med?) conditions.

These are book (manual) figures and what was done in the field to get P-40 fighter bombers out of North African or Italian or SW Pacific airfields with large loads of bombs I have no idea. Maybe the US construction engineers were able to carve out 3000ft plus airstrips in short order??

I would be very leery of claims of the SBD-1 (or even the SBD-2) taking off with 1600lb bombs. The SPD-3 was in production by the spring/summer of 1941. The SPD-1 and -2 did not have protected fuel tanks, The SPD-3 could be fitted with either protected tanks or unprotected tanks. The 1600lb bomb was not adopted until the fall of 1942 and didn't see service until some time in 1943. Most US carriers didn't keep more than 20 in their magazines, if they had any at all.
The 1942 manual for the SBD-3 calls for 853ft of take off distance with a 1000lb bomb and 100 gallons of fuel in self sealing tanks. With unprotected tanks and the 1000lb bomb and 100 gallons the distance was 701 ft. Weight of the self sealing tanks (or the difference) was 232lbs for the center section fuel tanks, 218lbs for the outer wing fuel tanks, 30 lbs for the oil tank and armor for the crew was 212lbs.

Granted, the really big bombs on aircraft with modest power do introduce a number of shortcomings, but it can be done.

It can, but needing a kilometer long hard surfaced runway might be considered a considerable shortcoming before the war starts or even in the first few years, even later depending on which air force we are talking about.

We gunners love our targets flying without change of speed, altitude or course (altitude preferably not being to small or too high, speed we want as low as possible). A bomber that is flying straight and level, .................................... They also leave less of favorable angles for pursuing fighters to tackle them.
The level bombers trying to bomb from altitudes that put them above the ceiling of 20mm will most likely be too inaccurate to hit the small target.

Good to know, WW II tactics, early war, often meant 6-12 planes playing follow the leader when doing dive bombing attacks. First flew planes might throw the gunners off quite a bit. Last 3-4 planes out of a dozen?????
You also left out part of the description of the P-40 procedure. after climbing to 4500ft slow the plane down to 150mph before rolling inverted. While this section says not to dive faster than 350mph IAS and earlier section says that it can take 5000-8000ft to pull out of a high speed dive.
I have no idea how fast you can get the P-40 to go when starting at 150mph at 4500-5000ft while inverted and pulling out with 500ft left under the plane.

My bespoke dive bomber for early war for RAF would've certainly have dive brakes (although the reinforced undercarriage is tempting, so it can be used in dive as impromptu dive brake), hopefully Merlins, size no bigger than Gloster F.9/37 (if 2-engined), bomb bay for one 2000 lb bomb (or more smaller bombs; bomb bay being something like the bomb bay on the Avenger or Helldiver), crew of 2 in tandem.

The Idea behind the SBD dive brakes (or the ones on the A-36) were that they would cause little or no trim change as they were deployed and retracted. Not sure that lowering the landing gear on most planes doesn't need trim change.

Bespoke Dive bomber for the RAF for the early war needs some Bespoke bombs. There were no 2000lb (or 1900lb) bombs or even production 1000lb bombs in 1939.

 

[Shortround6]

For the British a Skua MK III (Pegasus engine instead of the Perseus) and a bespoke 1000lb bomb might have made life rather miserable for the Kriegsmarine and quite possibly the Italians.

 

[tomo pauk]

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I would be very leery of claims of the SBD-1 (or even the SBD-2) taking off with 1600lb bombs. The SPD-3 was in production by the spring/summer of 1941. The SPD-1 and -2 did not have protected fuel tanks, The SPD-3 could be fitted with either protected tanks or unprotected tanks. The 1600lb bomb was not adopted until the fall of 1942 and didn't see service until some time in 1943. Most US carriers didn't keep more than 20 in their magazines, if they had any at all.
The 1942 manual for the SBD-3 calls for 853ft of take off distance with a 1000lb bomb and 100 gallons of fuel in self sealing tanks. With unprotected tanks and the 1000lb bomb and 100 gallons the distance was 701 ft. Weight of the self sealing tanks (or the difference) was 232lbs for the center section fuel tanks, 218lbs for the outer wing fuel tanks, 30 lbs for the oil tank and armor for the crew was 212lbs.

Data sheets for SBD versions (and a lot of other US aircraft) can be downloaded for free here: link.

For the British a Skua MK III (Pegasus engine instead of the Perseus) and a bespoke 1000lb bomb might have made life rather miserable for the Kriegsmarine and quite possibly the Italians.

Very good idea.
The Skua with a 2-speed supercharged Pegasus can comfortably cruise at higher altitudes (15000+ ft) and doing so avoid 90% of German Flak deployed away from Germany proper - unlike what the dive-bomber with a low-altitude engine can. All while still not having problems taking off with much increased payload. Skua was also a smaller aircraft than Battle, let alone Blenheim - this again improves the odds to the bomber and it's crew.