Fast bomber for USAAC: how would've you done it?

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The problem with trying to use twin fuselage fighters as bombers is that carrying stores underwing (or under fuselage/s) is a high drag way carrying them. Using the same engines a plane with a bigger fuselage, carrying the same bomb load inside will fly faster on the same power while loaded than the smaller plane carrying the load outside. Once the load is dropped the smaller plane will be faster. Faster also means that for the same power and fuel burned the bigger plane will actually go farther (more range). Depending on range desired and fuel needed the bigger plane may be the only way to go. Early A-20s carried 540 gal inside and later ones carried 725 gals, without bomb bay tanks. B-25s carried 692 gallons on early ones (or all?), B-26s carried 942 gallons and the A-26 could hold up to 1600 gallons in internal tanks. Some of these planes had the ability to swap part of the bomb load for bomb bay tanks which would have little or no effect on cruising speeds or dash speeds at the same weight. Hanging multiple fuel tanks and bombs under a "twin" fighter was going to result in a slow airplane while loaded. For instance a 'clean" Mustang could cruise at 15,000ft at 373mph using 90gph, while adding two 500lb bombs meant the plane cruised at 343mph while using 97 gph. adding six rockets was like using airbrakes, for the same 97gph the speed fell to 314mph at 15,000ft. Of course other altitudes and speeds could be used but you get the idea. For short range a "twin" fighter can carry a pretty good load but if you want to go far and go fast you are better off with a bigger fuselage and putting the bombs inside.
 
The problem with trying to use twin fuselage fighters as bombers is that carrying stores underwing (or under fuselage/s) is a high drag way carrying them.
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The most fuel efficient bomber would've been that (X)B-42 - single hull doing all the stuff. After that, we have Mosquito-like bombers.

We can also take a look at real bombers produced in WW2:
-Ju-88 He-111: bombs bigger than 100-250 kg were carried outside the bomb bay
-A-20, B-25, B-26: two radials plus a hull
No advantage over twin that carries bombs externally?

The twin P-47, non-turbo, can have two bomb bays, each slightly smaller than perhaps Avenger had?


Twin P-47: 600-740 gals internally; that's without cramming fuel into outer wings (permanent fuel tanks) 'bomb bay'.
 
A B-26 could carry two 2000lbs internally. B-25s and B-26s could carry at least six 500lb bombs internally. In fact later B-25s could carry six 1000lbs bombsof a certain type internally for short distances.

A B-26A could fly 1000 miles at 265 mph while carrying 3000lbs of bombs. A P-47 can't fly 900 miles clean at 12,000ft at 250mph.

A B-26B could fly 1020 miles at 15,000ft at 247mph on 900 gallons at a gross weight of 30-33,000lbs.
A P-47C could fly 880 miles at 12,000ft at 248mph on 265 gallons at a gross weight of 11-13,500lbs

Fuel loads given allow for warming up and taking off but no reserve.

Cutting hole in P-47 fuselages mean putting in reinforcements around the holes, putting in door actuators and so on. The more stuff that has to be modified the less commpnatitaly reamins and while it may "look like" a twin P-47 the differences start opile up to where you aren't really saving any thing.

Just because the Germans couldn't figure out how to put a decent bomb bay in plane doesn't mean that nobody could.

Down load. http://www.ww2aircraft.net/forum/at...ots-manual-naa-b-25h-erection-maintenance.pdf


And go to page 573 for an idea of what a real bomb bay could offer for different missions.
 
You do have a point here, so I'd like to scratch all that bomb bay mess and just go with recesses instead.
Having another, say, 2 x 75 gals (in outer wings) would've been nice thing to boost fuel quantity (2 x 305 gals + 2 x 75 gals = 760 gals).

Back to the XB-42, perhaps that was the best airframe to install early Packard Merlins (1-stage)? With proper use of exhaust thrust the total thrust is on par with 1325 HP turbo V-1710s (up to 15-20kft?; mid '42-mid '43), while the engine installation is far less complex of lower weight? That's, of course, 'our' Mixmaster (B-42B; B-42A would be the one with V-1710s like P-40s were using) is built in such a time frame.
A night fighter offspring too, maybe, with 2-stage Merlins (space permitting)?
 
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davebender said:
What's wrong with the bomb bays in purpose built German level bomber aircraft such as the Do-217, Ju-288, Fw-191 and He-177?
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Gee, I guess you got me Dave. Do-217 can carry eight 550lb bombs inside. in order to carry it's max internal bomb load of 5550lbs it needed to carry two 2205lb bombs and two 551lb bombs not ten 551s or 5 1102lbs bombs. Not bad for a medium bomber.

Ju-288 carried what? we know what was intended but with 17 out of 22 built crashing in testing perhaps the less said the better?

The Fw-191? another "what if" plane. With an internal bomb load of eight 551lb or four 1102 bombs it sure doesn't impress me for 50,000lb + bomber. Overload condition called for two more 1102lb bombs OUTSIDE.

The He-177? getting there. Six 1102 bombs inside. It can carry a lot more weight but it can't carry more big bombs. Six seems to be the max for bombs bigger than 551lbs. Yes, it can carry 6 2205lb armor piercing bombs but a B-17 can carry eight 1600lb AP bombs inside and it's bomb bay was designed in 1934-35. Again I am left less than impressed by the German bomb bay.

One service bomber that was the equal of it's contemporaries?
 
The Do-217E entered service during 1941. USA contemporary aircraft would be the B25C and B26A. All 3 aircraft are similiar in size (empty weight) and engine power. Each aircraft model has it's advantages and disadvantages. But I think the Do-217 compares nicely with the competition.
 

We can only speculate, but i wonder if two separate P-47s in bomber configuration wouldn't be equally as potent if not better than sending a larger target into battle.
You would think that there should be a benefit beyond the capacity of using two separate planes, maybe even three.
If using a twin P-47 only allows room for 500lbs more load, i'd say what's the point.
 
Shortround6 said:
P-47s used as bombers have crap for range. If you can't reach the target to begin with every thing else is moot.
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I think the issue was combat radius.
They made it to Germany and back. If they had to dogfight for 30 minutes they might be stretching it to get home.

If all they needed to do was fly and drop bombs and return, they could do that using a fast cruise.

Even so, would there be a benefit for range with twin engines?
and again, what benefit for load out?
Sort of a "what if" so i don't think there's a wrong answer.

It would be better to develope a high altitude Il-10. Maybe drop the armor for more load out. They might reach 400mph at altitude.
The original was doing 340 at 8000ft.
 
To get to Germany and back they used drop tanks on the way to Germany. Replacing the drop tanks with bombs means internal fuel or some combination of bombs and drop tanks. While some P-47s could get 2500lbs of bombs off the ground they weren't going very far.

A 305 gallon P-47 had an operational radius of 125miles according to one chart. the 370 gallon P-47 went to 225miles. A Mustang with 184 gallons under the same conditions went 150 miles. All at 25,000ft. at 10,000ft the Mustang could make 200 miles but adding a pair of 500lb bombs reduce the radius to 175miles at 10,000ft. A P-47N with 564 gallons had a radius of 400 miles at 25,000ft. Adding a pair of 1000lbs bombs cut the radius to 300 miles at 25,000ft.

Fighters can make a decent bomber substitute if you have lots of them and if the target is only a few hundred miles away (or less).

We have all seen the Pictures of P-40s with bombs. The drop tank weighed 366lbs for fuel+tank. If you want a 500lb under the fuselage and anything under the wings AND stay under gross weight you have to leave out some .50 cal ammo or fuel or both.

A P-47N with 2500-2800hp for take-off (with ADI) can get a lot more off the ground than a P-47C/D with 2000hp and a toothpick prop.
 
I think the best, most cost effective alternative for the US would be to simply licence build the Mosquito or undertake derivative development at an accelarated rate leading to the improved Hornet.

Someone said there was a shortage of wood to build these aircraft. I see two possible solutions to that, or more correctly two responses. the first is that I am unaware of any cutailment of Mosquito (or hornet) production due to a shortage of timber. There were vast areas of appropriate timber in 1940-45 suitable for use that remained untapped.

A possible alternative might be to adapt the basic design to be constructed in metal. Might need new higher power engines, but this would be able to be accommodated IMO.

Some criticism of the mosquito, or more correctly, airframes constructed in wood has been raised due to the "specialist" skills needed to use this material. Certainly wood working skills are not generally associated with the aero industry, but they are hardly any more specialised than those trades needed to work the special metals coming into general use in the '40s, like Duralumin. That, in fact, was one of the great attractions of the Mosquito...it could tap into a trades skill set not needed for other aircraft construction. You could basically use piano makers, cabinet makers, carpenters and similar tradespeople to work the material.

Some people have levelled criticism at the limited life of wooden airframes, particulalry in damp or tropical conditions. Certainly one would think that is the case. However the average lifespan of a Mustang airframe in 1944 was just 8 months, regardless of the combat attrition rate. Wartime airframes were flogged, and they just didnt last that long. Post war, the Hornets and Mosquitoes that were retained did not show any undue signs of fatigue or weather damage that I am aware of. RAAF Mosquitoes, built in 1945, were not retired until 1962, I believe the RNs Sea Hornets remained in frontline carrier based service through the 1950's. Hornets were also deployed to malaya for arduous frontline service...thats in 1957!!! So IMO, the specialist laminar construction bullet proofed these particular designs to rapid hull stress or deterioration due to weathering.

A few of the old timers that i trained under used to talk about repairs to these types of aircraft. Once the skillsets to undertake that work had been learned, repairs to damage were not an especially or unusual problem for them to handle. Anecdotal I know, but thats as good as I can provide.

Performance wise, a US derivative of the hornet, appearing say in 1943 with a 2000+HP could be expected to deliver the same, or similar performance to the Hornet, produced at wars end. Hornet was not prioritised in Britain, because the mosquito was so successful, but the US might want the added performance conferred on the hornet, by pouring greater resources into the program, so that the design and development could be worked out earlier. if they did, they could expect the following performance figures

Performance (Hornet)

Maximum speed: 472 mph at 22,000 ft (760 km/h at 6,706 m)
Range: 3,000 mi (4,828 km)
Service ceiling: 33,000 ft (10,058 m)
Rate of climb: 4,000 ft/min (20.3 m/s)
Armament


4 × 20 mm (.79 in) Hispano Mk. V cannons (with 190 rpg) in lower fuselage nose
2 × 1,000 lb (454 kg) bombs under wing, outboard of engines
8 × "60 lb" (27 kg) RP-3 unguided rockets
2 × Highball installation developed but not applied to fleet
Avionics
ASH radar fitted in Sea Hornet NF Mk 21.

With a clean top speed of 470mph, the type fully loaded is going to fly at around 370 mph at normal combat ranges. With a 3000 mile range, its combat radius (practical) will be about 1000 miles,more than enough to fly all the way to Berlin. At that speed, nothing in the german inventory in 1943 is going to catch them.....
 
Hornet was not a bomber, and I'm not sure it was big enough to carry two highballs.

A Mosquito made under licence in the US would have provided them with the fast bomber (if they needed it or knew they needed it) but not for a couple of years. When did Canadian Mossies first leave the production line - sometime in in 1943?
 

It wasnt a bomber, it was a fighter bomber, able to carry 2000lbs of bombs. But I think it quite possible to convert it to a dedicated unarmed bomber, along the lines of a Mosquito BIv.

Mossies were re-engineered in that way, but in the reverse direction. They started out as a Recon aircraft, morphed to a bomber, then to a fighter, then back to a bomber, carrying a heavier bombload, and then back to a fighter......there is no reason why the hornet could not do the same. There might be one issue, the fuselage profile of the Hornet was slightly narrower and deeper, but surely this could be overcome.

Canadian Mosquitoes began to roll off the lines from 1 june 1943, about 1 1/2 years after the Mosquito entered high volume production in the UK. I seem to remember the main problem was twofold....a shortage jigs to cut the templates, and a need to train the personnel on assembly and forming of the laminar building material.

The hornet design spec was not issued until mid'43, and first flight was in 1944, so timing might be a bit of a problem. Some things would have to happen for this to come to fruition at a reasonable time. The design spec would need to be issued at least a year earlier, and the US would need to come into the program from the start. A suitable 2000 HP powerplant would need to be available from the end of 1942, and the new glues used in the hornet (Redux...a stronger version of the epoxy that had been used in the Mossie) would need to be developed slightly earlier than it was, as well as the technique of bonding wood to metal. All problems, that would need to be solved but are these insurmountable for the yanks to overcome. I dont know....on the one hand they have some amazing engineering and design capabilities....on the other ther is this innate aversion to laminar construction methods that might damn the development process.

Early Hornet development is problematic, but if it were, it would have been a very potent addition to the US inventory....an interesting comparison to the F7f I guess. Perhaps a more realistic option would be simply to build the mosquito under licence, though the daydream of seeing Hornets in US service 1944-5 is appealing dont you think?
 
Captain Eric Brown was apparently extremely impressed with the flight characteristics of the Hornet. I vote for a Mosquito/Hornet type craft. Considering the comparable bomb load, I wonder if all those 8th Air Force B-17s had been replaced by Mosquitos would less lives have been lost while accomplishing the same mission?
 
parsifal said:
It wasnt a bomber, it was a fighter bomber, able to carry 2000lbs of bombs. But I think it quite possible to convert it to a dedicated unarmed bomber, along the lines of a Mosquito BIv.
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The Hornet was a fighter which could be converted into a fighter bomber by fitting externally mounted bombs.

I don't think the fuselage is big enough for a bigger bomb bay, and if the fighter is modified to make it possible you'd end up with teh Mosquito anyway.



The Mosquito was designed as an unarmed light bomber, with a bomb load of 1000lbs. At the time the prototype flew the MAP weren't completely sold on the idea of an unarmed bomber, but a high speed recce plane was required, and so that became the first priority. The MAP also wanted to see the Mossie as a long range day fighter, which would be the FII, which would later become the NFII when radar was added. The original production order of 50 had several changes of the mix of reconaissance, bomber and fighter versions. One of the FII prototypes was even fitted with a powered 4 gun turret (which wasn't, apparently, powerful enough to rotate the turret at speed). Another FII prototype was fitted with a mockup turret which had a number of positions teh mockup guns could be positioned.

The fighter bomber version came later, combining the cannon/mg armament of the FII and using the bomb bay area not taken up by the cannon.




Expect a similar timeline for US built Mossies.




I believe that de Havilland was working on the Hornet before the MAP issued the specification. The project was an on again/off again sort of project, as de Havilland failed to get a clear indication of the MAP's desire for such an aircraft. I believe a similar situation existed for the super Mossie - 430mph, 6000lb bomb load powered by two Sabres. Indecisiveness by the MAP may have also been a factor in the timing of the Vampire.

I genuinely believe the Hornet could have made WW2 had the MAP given de Havilland a clear indication that style of aircraft was very much wanted.

I am also sure that if the USAAF wanted a Hornet style aircraft they could have come up with it on their own. After all, they had massive R-2800 production, Packard Merlins were rolling off the lines and Allison V-1710 production was ramping up. In terms of 2000hp engines the R-2800 woud have been available at that rating from 1942, the Merlin was cleared for 2000hp in the low level Mk66 with 150 grade fuel from 1944.
 
The problem is that the USAAC was not as interested in an ultra high lightweight bomber as perhaps they should have. They were very much wedded to the concept of the heavy lift bomb truck, whether that be in the category of light, medium or heavy bomber, and certainly were disinclined to anything made of wood. In each category of bomber (light/medium/heavy) speed was of less importance to strength and defence, along with bombload. The idea of a lightweight high speed unarmed light bombload bomber was never going to attract any interst in the US procurement machine.

In that sort of environment, a hornet/mosquito/any indigenous design similar was going to attract zero interest. The prejudices and preconceptions were just far too strong for an idea like that to have any hope
 
The other problem you had in the US was what was actually possible for an airplane to do in the time period the US was looking at planes that would actually serve in the war. Given the both the Size of the US and distance from any likely enemy in 1938-39-40 one of the over riding requirements was range. For instance

"On March 11, 1939, the Air Corps issued Proposal No. 39-640 for the design of a medium bomber. According to the specification, a bombload of 3000 pounds was to be carried over a range of 2000 miles at a top speed of over 300 mph."

This lead to the B-25 and B-26 bombers. Now look at it again, this is 6 months before WW II starts, it is about a month before the Air Corps even orders the first production P-40s. Of the three engines suggested in the proposal only one was actually flying at the time. Compared to a Bristol Blenheim they wanted 2-3 times the bomb load, 50% more range and a higher top speed.

The first B-25s had nowhere near the armament of later ones, they were also much faster. The first B-25 had it's first flight Aug 19 1940. one week into the BoB. The early B-25s carried three .30 cal guns. one in the nose, one out the top (no turret) and one in the waist and a single .50 in the tail fired by a man laying prone. At the time (late 1939/early 1940) the plans for the Mosquito called for a 1000lb bomb load and a range of 1500 miles. At this point, before either flew, you would have needed 3 Mosquito to carry the same bomb load as 1 B-25. Good as the B-25 may have turned out to be the Mosquito was one of those rare planes that not only exceeded it's manufacturers expectations/calculations, it did so by a fair amount. This allowed for significant increases in payload before the plane went into service. As time went on RR increased the power of the engines considerable which only added to the capabilities of the Mosquito. The B-25 used pretty much the same power engines for the duration of the war which meant any increase in war load could only come at the expense of performance. It also meant that any increase in performance could only come at the expense of war load or redesign of the aircraft.

I don't mean this to be a comparison of the B-25 vs the Mosquito, just trying to show that in 1939/40 what was though possible for performance in the near future (service bombers in 1942) was different than what was possible just a few years later and procurement decisions should be looked at that way.
Perhaps the US should have traded either bomb load or range (or both) for more speed without guns. With engines available at the time (or in the foreseeable future) you weren't going to get bombload, range and speed even if you left a couple of crewmen and a few hand held guns behind.
 
What would have been needed would have been a fundamental change in tactical concepts. B-25s and B-26s were variations to a theme, that looked at the whole package....the americans wanted an aircraft with decent bombload, decent range, decent defences (armour added later) and thats exactly what they got. Nothing wrong with the philosophy...i happen to think the US mediums were the best in their class during the war.....but was a balanced allround design the way to go to producing the most survivable and effective bomber for the US. thats an open question.

The Mosquito was being designed and developed at roughly the same time as the US mediums, but followed a fundamentally different path. As a bomber, it looked for the most aerodynamically clean design possible, and this worked hand in glove with the idea of dispensing with defensive armament, to maximise speed. Speed and agility were the mosquito bombers defence.

I do not believe that the US would ever have accepted a Mosquito style solution, but I do believe that it was technically feasible for them to do so. Instead of building the rather large, defended type like the B-25. that was not particulalry outstanding aerodynamically they would have needed to design a smaller, better shaped aircraft with a smaller bombload. i dont know if building in metal was better or worse in this scenario, but building in wood was a provenm possibility at least...just never considered by the US.
 
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