Fast bombers again

[tomo pauk]

The Problem is for the 'fast, unarmed bomber" to actually work it has to cruise fast. Peak speed is pretty much useless if the plane has to cruise at low speed in order to reach the target. It could take a MK V Spitfire around 2 minutes to go from the low 200mph range to full speed. This is why they had to cruise at high speeds and why the US escorts flew at 300mph + and weaved above the bombers.
Unarmed bombers or bombers with sketchy armament are going to have to cruise fast. They cannot cruise slow and hope to accelerate and run when when bounced. The R-2800 was pretty economical at low power settings. It got real thirsty when pushed.

That is why I don't think that a B-26 would've make a good fast bomber. It would take a bomber that can max out at 370-380 mph, so it can cruise above 300 mph.

Sorry for the misunderstanding, I really wasn't suggesting the Tigercat as a bomber. It was the smallest twin R-2800 powered plane I could think of and if it couldn't fly the distances wanted at the speeds needed than any larger plane is going to have real trouble.

Roger that.
Main problem the Tigercat had to achieve meanigful ranges/radii is the meager volume of internal fuel. It is actually 426 US gals in early models, 455 US gals in F7F-3; the night-fighter did not carried nose tank so it went down to 375 US gals. That makes for under 230 US gals per engine in best case, and even the P-47C looks like a long ranged (if low flying) bird with it's 305 gals + 'cow udder' belly tank against the F7F.
The A-20 did not have R-2800, but was a bit bigger than F7F.

...
found a listing for the (X)TSF. Bay could hold one Mk 13-3 torpedo, one 2000lb bomb, two 1600lb AP bombs, four 1000lb AP bombs, two 1000lb bombs or four 500lb bombs...

Thanks for the data.
What I'd like for the bomb bay would be an longish one, so 2 x 2000 lb bombs can be carried in tandem, or 3 pairs of 500 lb-ers.

Sounds a lot like an A-26

Unfortunately, it was a bit too late in game, the 1st A-20s with 3 bomb bay tanks (= 325 US gals total, plus 400 gals of wing fuel) were not produced before 1944 I believe.

How fast does the unarmed/lightly armed bomber have to fly to get a reasonable measure of safety?
Granted you do not have to fly all of the mission at high cruise speeds, just the parts over enemy territory.

That depends on when and where.
The DB-7 was a reasonably safe aircraft vs. LW fighters (and Flak) in 1940, of 64 in service only 8 were lost to fighters and Flak during the BoF. That is for a 305 mph aircraft vs. 350 mph Bf 109 and 320 mph Bf-110; however it cruised at 270 mph. Granted, the tasks were not that long ranged. Soviet Pe-2 and Tu-2 were also reasonably safe aircraft vs. LW opposition (especially if we apply Soviet standards of ww2), though the performance disadvantage was considerable.
The faster bomber should be a more riskier target to take head-on, and it will also be harder to hit from side quarters. Faster aircraft should be also safer vs. Flak, not just presenting itself as a tougher target to acquire a good firing solution, but will also allow for fewer shells/burst to be fired upon it.

 

[Shortround6]

That is why I don't think that a B-26 would've make a good fast bomber. It would take a bomber that can max out at 370-380 mph, so it can cruise above 300 mph.

ANd there you pretty much have it. The Mosquito MK IV with Merlin 21s had a top speed of 380mph at 14,000ft but what was more important was that it could cruise at 320mph at 15,000ft with the engines running at max lean.

Range was a theoretical 1360 miles under such conditions with standard fuel. 536imp or 643/4 US gallons. Please compare to the figures for the A-20B given in previous post. Mosquito had 10 more gallons to start with, carried the same load and either flew much, much faster or went much further or a combination of both. 1625 miles at 265mph. Mosquito could fly roughly twice as far on the same fuel carrying the same load. A-20B carried four fixed .30 cal, a pair of .30 cal out the top and a single .30 cal out the bottom (often manned by the top gunner) so ditching the guns doesn't save much.

http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV-merlin21_ads.jpg

Main problem the Tigercat had to achieve meanigful ranges/radii is the meager volume of internal fuel. It is actually 426 US gals in early models, 455 US gals in F7F-3; the night-fighter did not carried nose tank so it went down to 375 US gals. That makes for under 230 US gals per engine in best case,

And to fit a lot more fuel inside you need a bigger plane, even if you throw out the guns/radar and other bits.

What I'd like for the bomb bay would be an longish one, so 2 x 2000 lb bombs can be carried in tandem, or 3 pairs of 500 lb-ers.

It's possible but you have a bomb bay about 5 meters long.

The DB-7 was a reasonably safe aircraft vs. LW fighters (and Flak) in 1940, of 64 in service only 8 were lost to fighters and Flak during the BoF. That is for a 305 mph aircraft vs. 350 mph Bf 109 and 320 mph Bf-110; however it cruised at 270 mph. Granted, the tasks were not that long ranged. Soviet Pe-2 and Tu-2 were also reasonably safe aircraft vs. LW opposition (especially if we apply Soviet standards of ww2), though the performance disadvantage was considerable.
The faster bomber should be a more riskier target to take head-on, and it will also be harder to hit from side quarters. Faster aircraft should be also safer vs. Flak, not just presenting itself as a tougher target to acquire a good firing solution, but will also allow for fewer shells/burst to be fired upon it.

Here we hit the real problem for the Americans, the DB-7 and the PE-2 were rather short ranged and/or carried rather small bomb loads. Fast bombers that carry 4-6 250lb bombs aren't going to have the impact (target effect) the high command were looking for ( not to be confused with what they actually got in service).

AN American fast bomber using radials is going to have rather short range which limits it's use in the Pacific and in NW Europe, Might work OK in the Med.

Can you get the cruise speeds you want with the engines running in lean conditions?

 

[tomo pauk]

I was able to find these values, for operations between 10 and 20 kft, max listed power on lean mixture:
- R-2600-23 (used on most A-20s, with 1600 HP for TO) - 855 HP, 70 US gals/hr per engine
- R-2600-13 (used on B-25, 1750 HP for TO) - 905 HP, 90 gph per engine - a reason why those engines substantially cut the range/radius when installed on some A-20s
- R-2800-43 (on B-26 later variants) - 960 HP, 98-99 gph per engine at 16-18 kft
- R-2800-8 (as on F4U) - 970 HP, 93 US gph per engine

For the V-1650-1, on second gear, it was 758 HP at 16000 ft, 63 US gph per engine (or 52 IMP gph), lean mixture. That is not the end of the equation, the Merlin will have less drag, especially when the Whirlwind/Mosquito-type radiators are used. It will also be easier to use the exhaust thrust to the fullest, less so with the Western radials of the time.

(about the F7F: )

And to fit a lot more fuel inside you need a bigger plane, even if you throw out the guns/radar and other bits.

Packing the fuel in the wings helps, especially if they are big. Mosquito have had circa 550-600 US gals in wings (corrections welcomed), the A-20 - 400 US gals, F7F - none, despite 455 sq ft wing, in the ballpark with Mosquito. But then the F7F was not conceived as a bomber.
The wing of A-20 was also there, 460 sq ft. The bomb bay tanks (1 in front, 2 in aft part, for 325 gals total) were a straightforward expedient on the A-20s, leaving also place for bombs to be carried inside.

Here we hit the real problem for the Americans, the DB-7 and the PE-2 were rather short ranged and/or carried rather small bomb loads. Fast bombers that carry 4-6 250lb bombs aren't going to have the impact (target effect) the high command were looking for ( not to be confused with what they actually got in service).

I was not suggesting that DB-7 and Pe-2 would be a solution, but trying to underline that a fast bomber stand better chances than a slow one, when going against a capable numerous enemy. Both UK and USA have much better engines in disposal than what was installed on DB-7 or Pe-2; the engines being one of the main determinants of a capable aircraft.

AN American fast bomber using radials is going to have rather short range which limits it's use in the Pacific and in NW Europe, Might work OK in the Med.

There are several things that can help out the Pacific service. 1st might be the geography. Over water/when not close to enemy airbases, the aircraft can cruise on leaner settings, thus increasing the range. The opposing fighters are not that fast (though they are faster than West expected before P.Harbor ), the radar coverage ranges from sketchy to non-existent, the AAA suite is perhaps 1/10 of what can be expected in ETO. The armament of the fighters is not as heavy as what LW had. A bomber that maxes out at 330-350 mph is lighting fast in Asia/Pacific.

 

[nuuumannn]

For the mosquito would a fore aft sitting position be better for drag and space for the navigators aids?

The problem would be that the nose would have to be lengthened and I don't know if its going to do anything more than change the nav's position, if it really required changing at all. The Sea Venom and Vampire NF.10 adopted the same diameter nose section of the Mosquito to produce a two seater with radar fitted and they were side-by-side seating, with ejection seats in the Sea Venom but not the Vampire night fighter. Are you thinking along the lines of the Martin B-57 versus the British Canberra?

AN American fast bomber using radials is going to have rather short range which limits it's use in the Pacific and in NW Europe, Might work OK in the Med.

Essentially the issue is that in order to maintain a high cruise speed, the airframe must have low drag, which means minimal excrecenses; no turrets or other bumps and things protruding into the airflow. radiator and intake installations have to be clean, exhaust best to be thrust augmentation, low drag nacelles, no protruding wheels or bumps to house them, clean, fuse to wing mating. Also, the bomb bay has to be the right size to carry a useful bomb load over a good distance at relative high speed. Hmmm, beginning to sound like a Mosquito... Why don't the Americans just build them under licence?

 

[Denniss]

Mossie had about 400 imperial gallons in wing tanks

 

[pbehn]

Why don't the Americans just build them under licence?

Much as I love the mosquito I believe that its construction was just as advanced in its way as for example the P51 was. Yes the mosquito was made of wood but you couldnt just walk into a forest and walk out with an aircraft. The woods involved were almost as exotic as the metals in a turbine, they came from all over the world and had special procedures for bonding. How much of the wood in a Mosquito came from the UK and how much of a Mosquitos construction is shared with a piece of furniture? Goering couldnt make a mosquito because he couldn't import the wood, some of which I believe was ironed by American housewives.

 

[nuuumannn]

The thing with the Mossie was that it was using existing technology; it was an innovative use of procedures and processes that had been used before. I'm pretty certain that the US could have built the Mossie since woods like Douglas Fir were imported from the USA and Canada at any rate. My point was (It was made largely tongue-in-cheek since it's a debate that crops up a lot on the forum - could or would the US build Mossies under licence) that why would the US - this is if they were to find a specific need for a fast bomber during the war - pour so much effort into reconfiguring an existing design or even coming up with a new one if there was one already in existence that they could either order, which they did as PR aircraft, although they were allocated Mosquitoes from Canadian production that were not used, or build themselves if the requirement arose? The problem the Brits had was every Command wanted them, but the factories building them couldn't build them fast enough. Having US production would have made more available for British and American stock.

 

[pbehn]

The thing with the Mossie was that it was using existing technology; it was an innovative use of procedures and processes that had been used before. I'm pretty certain that the US could have built the Mossie since woods like Douglas Fir were imported from the USA and Canada at any rate. My point was (It was made largely tongue-in-cheek since it's a debate that crops up a lot on the forum - could or would the US build Mossies under licence) that why would the US - this is if they were to find a specific need for a fast bomber during the war - pour so much effort into reconfiguring an existing design or even coming up with a new one if there was one already in existence that they could either order, which they did as PR aircraft, although they were allocated Mosquitoes from Canadian production that were not used, or build themselves if the requirement arose? The problem the Brits had was every Command wanted them, but the factories building them couldn't build them fast enough. Having US production would have made more available for British and American stock.

I agree nuuumannn but the point I was making was that the mossie used very exotic laminates, balsa for lightness and for bulk but also some hardwood laminates. There is a popular notion that the mosquito, purely by the genius of designers, produced a miracle aircraft that could be hewn from any local forest. Building a mosquito was just as exacting as any other and although all discussions start with the mosquito being made from wood and using readily available labour was it actually cheaper than a comparable A/C?

 

[tomo pauk]

...
Essentially the issue is that in order to maintain a high cruise speed, the airframe must have low drag, which means minimal excrecenses; no turrets or other bumps and things protruding into the airflow. radiator and intake installations have to be clean, exhaust best to be thrust augmentation, low drag nacelles, no protruding wheels or bumps to house them, clean, fuse to wing mating. Also, the bomb bay has to be the right size to carry a useful bomb load over a good distance at relative high speed. Hmmm, beginning to sound like a Mosquito... Why don't the Americans just build them under licence?

As in a previous fast bomber thread ("an US mosquito" or something like that), Mossquito comes out as a measuring stick. The easiest, if not the best way to equal/surpass it's combination of performance (whether dash speed or cruise), bomb load and range would be to make a 'carbon copy' of it.
IIRC five (or four?) US companies were approached by the USAF with the question of the license building Mossie (Curtiss, Beech, Fairchild, and who else?). The replies was either we can't do it, or we can come out with something better. A wasted opportunity indeed.

Mossie had about 400 imperial gallons in wing tanks

Thanks.
That works out to 480 US gals.

 

[nuuumannn]

I agree nuuumannn but the point I was making was that the mossie used very exotic laminates, balsa for lightness and for bulk but also some hardwood laminates. There is a popular notion that the mosquito, purely by the genius of designers, produced a miracle aircraft that could be hewn from any local forest. Building a mosquito was just as exacting as any other and although all discussions start with the mosquito being made from wood and using readily available labour was it actually cheaper than a comparable A/C?

You're right in that perception, but I'm pretty certain that with American resources, Mosquitoes could have been manufactured. Price doesn't really come into it as a deciding factor once a requirement during the war becomes concrete; obviously if something can be done cheaper or more effectively, then yes, but if the Americans wanted (and still want) something bad enough, enough money would be thrown at it until it became reality - see F-111, B-29, B-1, B-2, F-35 etc.

 

[Denniss]

Mossie Fighters had 452 IG (an additional 50 IG tank was in upper bombbay). A 63 IG long range tank was possible (instead of internal bombs). Mossie Bombers and Recons had more internal fuel - no armament and more space for fuel tanks, resulting in 536 IG in permanent tanks.

 

[Shortround6]

You're right in that perception, but I'm pretty certain that with American resources, Mosquitoes could have been manufactured.

Americans would have had to get their Balsa wood from South America, just like the British and Canadians.

See: Ochroma pyramidale - Wikipedia, the free encyclopedia

 

[tomo pauk]

Come to think about it - the Germans were in a good position to make a Mosquito-like bomber, even if it's made in metal rather than in wood. Their V-12 engines were on par with 20-series Merlins, with a benefit of bit of a lower consumption, cca 10%. The DB-601A was already making 800 PS (790 HP) on max lean (!) at 5.5 km, the DB-601E was good for 840 PS at 5.1 km.

 

[Timppa]

Americans would have had to get their Balsa wood from South America, just like the British and Canadians.

Americans would have reverse-engineered it as all-metal, using even 7075 alloys. So it would have been a bit lighter, also.

 

[tomo pauk]

The quirk with having a wooden aircraft in production is that uses the work force seasoned in one material, that is not so far used by war industry. The re-engineering the Mosquito to be built in metal will also took time, and as-is it was one of lighter aircraft, tare weight was at 13400 lbs for single-stage Merlinized, vs. 17300 lbs for the Boston IV (equivalent of the A-20G-20). The US-built aircraft were known by many good tings, the light weight was not high on the agenda, though

The US-built Mosquito might use the Packard Merlins, and/or maybe the V-1710s, once they can provide 1325 HP for take off (from mid-1942 on). The single stage V-1710 will consume 67 US gals per hour when giving 750 HP at 10800 ft, the Packard Merlin V-1650-1 will consume 63 gph for 758 HP at 16000 ft, and 65 gph for 810 HP at 9500 ft.
At lower ratings, on lean mixture, the V-1710 will give 670 HP @ 10800 ft @ 50 gph, vs. the V-1650-1 making 700 HP @ 10000 ft @ 65 gph. On max continuous, the V-1650 will give 10-80 HP more while using ~12% less fuel, Those V-1710s are a bit lighter than V-1650-1, 160-170 lbs.
If the longer 2-stage V-1710 can be installed (due to CoG reasons), it might power the US night fighter version, along with a bomber and/or recon version. It is also heavier, 170 lbs more than V-1650-1.

 

[pbehn]

You're right in that perception, but I'm pretty certain that with American resources, Mosquitoes could have been manufactured. Price doesn't really come into it as a deciding factor once a requirement during the war becomes concrete; obviously if something can be done cheaper or more effectively, then yes, but if the Americans wanted (and still want) something bad enough, enough money would be thrown at it until it became reality - see F-111, B-29, B-1, B-2, F-35 etc.

Nuuumannn i didnt mean that cost was an issue but the cost of something usually reflects the difficulty in manufacture. No doubt the USA could have made them, whether they could have set up the operation in time to make a difference is another matter. Mosquitos were made in many locations.



Production[2]
Producer and site Number built
Standard Motor Company, Coventry 1,066
Percival Aircraft Company, Luton 245
de Havilland Leavesden, Hertfordshire 1,476
de Havilland Hawarden, Chester[nb 16] 96
de Havilland Hatfield, Hertfordshire 3,326
de Havilland Canada, Toronto 1,076
de Havilland Australia, Sydney 212
Airspeed Aircraft, Portsmouth 122

Although many people worked with wood I think the skills required are more like those of a cabinet maker than a "joiner".

 

[nuuumannn]

True, pbehn and I guess with the pressures of wartime, if there is a real need for something, it'll get done. Just like in America. I don't think supply of balsa from South America is going to provide much of a hindrance to US production, really. Building the Mossie in metal might make it lighter, but the problem is that the wooden finish of the outer fuselage was very clean with few panel lines and so forth. redesigning the aircraft to be built in sheet metal would change its exterior finish, that's not to say that it wouldn't be possible, but could it be as clean as the Mossie was? It'd be interesting to find out just what modifications to the exterior structure would have to be made.

Come to think about it - the Germans were in a good position to make a Mosquito-like bomber, even if it's made in metal rather than in wood.

Yep, indeed, but it boils down to philosopy, as mentioned earlier. Before the war the German idea of a fast bomber was the Ju 88, nowt wrong in that as it was a terrific aircraft, but streamlining of the Ju 88 didn't quite match that of the Mosquito. Could an unarmed Ju 88 with better attention paid to external finish produce a truly effective fast bomber like the Mosquito, as our benchmark, I wonder?

 

[pbehn]

Nuuumaan, Im not an expert but I believe that some curves and contours of the Mosquito are almost impossible in metal. I saw a Halifax in Yorkshire (Elvington museum) the surface finish was closer to that of a ship than a mosquito, rough panels riveted together, absolutely nothing like that shown on the mosquito in your photo. The supermarine 327 was a fighter but from the side shows what a metal mossie may have looked like, it just needs a bigger fuselage and twin seats.

https://www.google.co.uk/search?q=s...rcharged-piston-aero-engines%2Fpage-8;600;426

 

[Shortround6]

True, pbehn and I guess with the pressures of wartime, if there is a real need for something, it'll get done. Just like in America. I don't think supply of balsa from South America is going to provide much of a hindrance to US production, really.

Kind of depends on how many you want to make, A few hundred at a dozen or so a month or 12,000 at 200 a month or better. While Balsa is grown on plantations now, back during WW II it was pretty much wild and it was low density growth, no Balsa forests like pine or spruce. 2-4 balsa trees per hectare was common. Granted you could log all year long with fewer problems than trying to log in Canada all year long but massive increases in Balsa production might not have been possible.

Yep, indeed, but it boils down to philosopy, as mentioned earlier. Before the war the German idea of a fast bomber was the Ju 88, nowt wrong in that as it was a terrific aircraft, but streamlining of the Ju 88 didn't quite match that of the Mosquito. Could an unarmed Ju 88 with better attention paid to external finish produce a truly effective fast bomber like the Mosquito, as our benchmark, I wonder?

Your answer may lie in the JU 88S.
Without Nitrous it had about the same max cruise as a single stage Mosquito. Trouble is the 167 imp gal less fuel unless you start filling up the bomb bay/s. Now maybe you could put extra tanks in the outer wings or only put fuel tanks in the upper part of the bomb bay and leave enough space in the lower bays for four 550lb bombs if you can reconfigure the bomb bays/fuselage.

What is harder is that even with 637 gal imp at 328mph at 18,000ft the Ju 88S had a range of about 929miles. ( multiplying endurance times cruising speed) or about 1.46miles per IMP gallon. the Mosquito was doing about 2.1miles per imp gallon at 327mph at 15,000ft with Merlin 23s. The JU 88 is going to need a LOT of streamlining.
If somebody has better figures for the JU 88 please bring them out as mine are from Green and maybe in error.


A Me 210C is also an interesting data point. Granted it has guns but it is a somewhat smaller aircraft than the Mosquito and had a skinnier fuselage. It was 20-30mph slower at similar altitudes. It could hold 550imp gallon internal and had a shorter range than the Mosquito. Lets assume you could trade the guns for a slightly larger bomb bay that would carry four 550lb bombs. Even with DB 605 engines it is slower and shorter ranged.

The Mosquito is a very, very hard act to equal or come close to. How much you can miss the mark by and still have a useable fast bomber (low enough losses to sustain a campaign) I don't know.

 

[nuuumannn]

Kind of depends on how many you want to make, A few hundred at a dozen or so a month or 12,000 at 200 a month or better. While Balsa is grown on plantations now, back during WW II it was pretty much wild and it was low density growth, no Balsa forests like pine or spruce. 2-4 balsa trees per hectare was common. Granted you could log all year long with fewer problems than trying to log in Canada all year long but massive increases in Balsa production might not have been possible.

Yes, I guess that could create a problem, but not insurmountable if resources were properly devoted to the issue. The Aussies managed to build them, too, so being further away and considerably more isolated than the US andf UK, it was certainly possible, if not a little late. The demand was high in Britain and the number of Mosquitoes produced was high - for British production - over 7,000. As for rate of production, it also depends on what contracts are put in for what numbers - are the US going to build to supply Britain or their own needs, or both? Even without a US need, there was high demand for the Mossie. Conversion to a metal structure precludes the debate regarding availability of Balsa, however.

The JU 88 is going to need a LOT of streamlining.

That's the crux of the matter, same with the Me 210. recently whilst reading about the Bf 109 and '110 I read about the Bf 162: Messerschmitt Bf 162 - bomber and wondered about the suitability of it as a schnellbomber, being the loser to the Ju 88. It was certainly smaller, being based on the Bf 110. Also, your staement earlier (in another thread?) about high cruise speed is very important; I'm not so certain that slicking these German types and making changes to war and fuel load enable a higher cruise speed.

The Mosquito is a very, very hard act to equal or come close to.

Very true, but not impossible, of course. It was the result of contemporary thought and technology, unlike say, the Whirlwind that had so much promise and advanced features in its design, relying on streamlining as a key to its performance, but falling down in certain areas of technical execution (different aeroplanes I know, but the Mossie serves as a benchmark for so much in twin engined aircraft design and application).