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Actually yes and no...An ASW plane, that flies most of the time practically on the deck, needs different engines and/or engine settings than a bomber or an airliner flying mostly above 20000 feet......
Actually yes and no...
The P-2 and later P-3 as we know spend a lot of time on the deck, but to get "on station" they flew at higher altitudes, it was only during patrols that you saw them down low, and this was probably emphasized in post war ASW doctrine. I do know the P-2 didn't have a great service ceiling, about 20K IIRC.
Everything is a tradeoff. Was the faster transit time the turbo offered worth the weight of the turbo installation in fuel for a given gross weight
A plane with 2 speed supercharger could cruise at decent heights to begin with. Lockheed Constellations didn't have turbo. Of course they weren't loaded down like some bombers were either.
Actually yes and no...
The P-2 and later P-3 as we know spend a lot of time on the deck, but to get "on station" they flew at higher altitudes, it was only during patrols that you saw them down low, and this was probably emphasized in post war ASW doctrine. I do know the P-2 didn't have a great service ceiling, about 20K IIRC.
During the (actually still on going) search for Malaysia Airlines MH370 which was thought to be lost over 2500km/1550 miles from Australia's West Coast the problem of transit times to and from the search area became significant for RAAF P3C. The Boeing 737 based P8 (USN or USAF?) that became involved acquitted itself quite well because of its greater transit speed.
If speed is the issue (maneuverability not a primary factor). Fast heavy bombers might be feasible too. Designs similar to the B-17 and B-24 but designed with no provision for little/no defensive armament and more emphasis on drag reduction. (the experimental V-1710 powered B-17 derivative proved substantially faster than the R-1820 powered one -fan cooled radial configurations might have been possible too or even 4 engined R-2800 powered bombers)Good summary (of the heavy bomber part of the query), thanks!
The second part of the question concerned a higher performance medium bomber.
There has been much discussion (on this board) of the concept of allied "schnell bombers" in the ETO and elsewhere.
For example, we frequently discuss the use of swarms of Mosquitoes in lieu of armed heavy bombers.
Perhaps a 2-engined R-3350 craft could fit into that discussion.
If speed is the issue (maneuverability not a primary factor). Fast heavy bombers might be feasible too. Designs similar to the B-17 and B-24 but designed with no provision for little/no defensive armament and more emphasis on drag reduction. (the experimental V-1710 powered B-17 derivative proved substantially faster than the R-1820 powered one -fan cooled radial configurations might have been possible too or even 4 engined R-2800 powered bombers)
Turbocharged R-2800 powered medium bombers with an emphasis on speed should have been practical. And light/medium bombers with R-1820/1830 or V-1710s should have been possible too. (or a 'light' bomber with the bomb capacity of a medium bomber - a la Mosquito) Something like a turbocharged B-25, B-26, or A-26. (or maybe A-20)
4.A bomber with four R-2800s is more like 4/5ths B-29 than a direct replacement for the B-17/B-24.
Small/tight cowlings better suited to high-speed aircraft, but less useful for low/moderate speeds. (particularly in the >350 MPH or >.5 mach range)3. Fans seem to have rather overblown reputation. Used basically to help cool off radials while taking off or climbing when the plane can't get enough airflow through the cowling due to the cowling being too small or having too small openings.
They also weren't generally interested in unarmmed fast bombers of any size ... regardless of range and bombload capabilities.The US wasn't interested in light/medium bombers with R-1820/1830 or V-1710s.
It's not just a matter of high altitudes at the levels B-17s and B-24s usually cruised at, but anything above medium altitudes, at least if you wanted economical cruise power and fuel consumption. (and the American heavies may have been too vulnerable when dropping their altitude a few thousand feet to improve accuracy, but this would have been different if they were flying close to 100 MPH faster)The XB-28 did use Turboed R-2800s. The USAAF had decided that medium bombers bombing from high altitudes wasn't going to work well. Something that also killed the Turboed A-20. Along with the fact that early R-2600s didn't seem to take to turbo charging very well. Early R-2600 powered A-20s had some cooling problems and adding the turbo didn't help.
And they'd already swapped the engines with the R-4360s not maturing in time and the R-3350s used in the interim. Part of the reason it was initially underpowered.Early B-29s suffered from being under powered so you just can't swap engines. You need a different/smaller airframe. The question is do you want a "safe" low tech airframe (unpressurized and using existing defensive armament turrets) or do you want the 'advantages' promised by the high tech B-29?
You will get different speed and range numbers depending on which option you pick.
Another interesting concept to explore.
We often say that lots of good enough now is better than waiting for perfection to arrive after it's too late.
Or something like that.
The point is, perhaps 4/5ths B-29 could have entered service sooner and had a greater impact on the war?
Don't want to be too quick to draw conclusions, rather it would be more fun to explore the idea.
I think the point here would be less a literal 4/5ths of a B-29 and more a totally different purpose-built aircraft intending to use 4x R-2800s either a similar, but somewhat smaller alternative to the B-29 (or B-32) or a more radical design focusing on the unarmmed (or nearly unarrmed) concept. The only thing remotely close to that in development during WWII in the US was Northrop's Flying Wings. But ... something consdierably more conservative in as far as conventional wing/body configuration but still aiming at high speed and light or no armament (and targeting lower power engines) would have been significant.
Small/tight cowlings better suited to high-speed aircraft, but less useful for low/moderate speeds. (particularly in the >350 MPH or >.5 mach range)
For lower speeds, the added weight, complexity, and power loss at low speeds makes it unattractive compared to similarly well designed cowlings with larger area. (and cuffed propellers)
They also weren't generally interested in unarmmed fast bombers of any size ... regardless of range and bombload capabilities.
A mosquito-like bomber using turbocharged V-1710s would have been pretty interesting. (or even Ju-88 like ... without the defensive armament and dive bombing being mandated)
Then again something slightly larger using R-2800s might have been more useful on the whole. (perhaps even something similar tot he B-17 or B-24 mission profile in terms of range and bombload, but smaller, faster, and lighter, and with less crew)
As far as using the R-2800 in lieu of the R-3350 for the B-29, I think it would be possible. PW R-2800 with water injection were producing 2200hh-2300hp in the P-47 by 1943, 2600hp by 1944 and 2800hp before 1945 on the P-47M. The question would arise as to whether the R-2800 overboosted with ADI (Anti Detonation Injection) of Water and Alcohol would work for a bomber in slowly accelerating take-off roll when there was less airflow versus a P-47 using it for an extra burst of speed.
Maximum power output of the R-2800 series was sufficient for take-off and emergency power, but the problem comes with cruise power. Either you'd have to run at lower power levels to reach good fuel economy (but suffer lower cruise speeds) or sacrifice range by operating beyond maximum cruise power. (and not being able to use lean mixtures)As far as using the R-2800 in lieu of the R-3350 for the B-29, I think it would be possible. PW R-2800 with water injection were producing 2200hh-2300hp in the P-47 by 1943, 2600hp by 1944 and 2800hp before 1945 on the P-47M. The question would arise as to whether the R-2800 overboosted with ADI (Anti Detonation Injection) of Water and Alcohol would work for a bomber in slowly accelerating take-off roll when there was less airflow versus a P-47 using it for an extra burst of speed.
There's other issues like power output, supercharger/turbocharger developments and compatibility, and overall development path of the R-2800 being smoother. (the R-2600 had some engineering problems, some related to the lead designer being taken off the project due to German heritage, I believe)This is why the R-2800 so quickly 'stole' the market the R-2600 created.
Most prototype turbo installations with R-2600s appear to have been unsatisfactor for one reason or another, I'm not sure why but it's one of the reasons the R-2800 was more successful.I recall reading in "Wings Magazine" that a turbo charged Curtiss Wright R-2600 was at one time considered for the B-26 Marauder and that with this engine top speeds of 400mph were estimated. For some reason work on this engine was abandoned.
The R-3350 was a pre-war design.The problem with the R-3350 in general is similar to that of the Bristol Centaurus. It's a late-war design that had barely matured by the end of the war. Granted, the R-3350 progressed well enough to be pressed into service in fairly large numbers on B-29s, unlike the Centaurus.
The A-20 itself seems like it might have fared well enough in a mosquito-like role, though the internal bombload was more limited. (more limited than the Ju-88's maximum internal load too, though not limited to the small, vertically oriented bombs as on the Ju-88 )A-20s and B-25s were going into service with US squadrons 9 months to year before a Mosquito dropped a bomb in anger. The summer of 1942 is not the time to try switching production lines.
Interesting yes, but interesting isn't the same thing as useful. And I am still having trouble seeing the JU-88 as some kind of wonder plane. 25mph slower than an A-20 (the JU-88A-4), Range isn't much better, if any better, both had a variety of fuel tank set ups so make sure you are comparing the right things. The Ju-88S-1, so beloved by advocates of fast bombers, shows up in the Autumn of 1943, only a few months ahead of the A-26. Not much of a contest as to which was the better bomber.
Switching from turbocharged V-1710s to R-2800s doesn't result in a "slightly larger" airplane. You have added well over a ton of engine weight and more like 1.5-2 tons of powerplant weight. Powerplant weight (for piston engines) went about 30-40% of all up weight (clean) for fighter type aircraft. For "light " bombers it is a bit less. Throw in the fuel you need to feed the R-2800s and AUW goes up in hurry. Again lets compare apples to apples. A-26 used an air foil and flap system that didn't exist in 1939-40. The A-26 could have been speeded up a bit but you weren't going to get them in service in 1942 without a time machine.
I was referring to maturity as a reliable production design. I'm not really sure the V-3420 would have been a better alternative there either given its own maturation cycle.The R-3350 was a pre-war design.
It certainly had a lot of "teething" problems, (which were resolved towards the end of the war), so much so, that the XB-39 was developed as an alternative (powered by the Allison V-3420-11) to the B-29 in case the R-3350 didn't work out.