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It depends just how far out on the "what if" branch you want to go.
The planes that you refer to ( I think) used new wings, new tails, new landing gear and mostly new fuselages.
In short they were new planes.
As far as the R-2600 itself went, it was larger in diameter than the R-2800 but lighter. With Wright trying to develop the R-3350 and the Tornado engine at the same time ( and the head designer of the R-2600 banned from the factory because he was German) the R-2600 might not have gotten the development needed to keep up.
It may have had a problem with turbocharging and almost all (or all?) production versions used single stage superchargers which in historical form limited the critical altitude to around 15,000ft at best.
So you need a new airframe and engine development that the engine did not get historically.
How far do you take the 'what if"?
First.
In our case the "what if" was a kind reality since in 1943/44 TsAGI made a lot of studies with american/english engines adaptations on soviet airframes. This point was already threated in our forum. Browse the archives...
Of course, the M-82 FN powered La-5 performed better than the theorycally fitted R-2600 one. The R-2600 was rather optimised for bigger planes like Il-4 or Yer 2 in wich case it's size disavantage were less marqued.
Moreover both soviet bombers had tendency to be underpowered. And so for the LaGG-3.
But all that was for mid 43/ early 44. But from the GKO report, on march 1942, the 25th...
Secund
...it was reported directly to Stalin that 36,7% of the plane inventory both in front-lines and PVO units was permanently unavaible. Mounthly some 5500-6000 planes and 2500-3000 engines were repeard in rear and front line units, buy the way some 5500-6000 planes and 3500-4000 engines were send to reparations.*
So 4500 unrepeared planes and regulary growing from 500-1000 engines rate per mounth, 7500-8000 engines were reported immobilised from mounth to mounth!
In that situation, there was no question for optimised engines or not, the question was just to have some, not only "good" R-2600's, but even the "rottest" and "weakest" ones from the west.
Third
You can also consider the I-185 prototype as powered with a kind of very heavy R-2600, that M-71 was during the february 1941 trials.** Not an especially bad performance with 665 km/h calculated at altitude.
*Alexeïenko VIJ 2001
The available M-71 was overweighted from 13%, and underpowered from 15% at least.
**Gouglya, the last polikarpov fighters, arkhiv press-1998
Just to say, for soviet industry in 1942 the reliable R-2600 would have been not an option more, but a kind of "heavens present".
Regards
To take the third point first. The I-185 was NOT powered by "a kind of very heavy R-2600".
It was powered by a crude R-3350 , because it used the same stroke as the original Cyclone instead of shortening it,,actually it was a 3,643 cu in engine.
If you are talking about a strictly HP to frontal area ratio then you are right.
Of course, it was it that sense, the airflow didn't take care about trademarks. And about weight to power ratio too. M-71 was 1079 kg heavy that time.
For your second point, what "rottest" and "weakest" ones from the west." in March of 1942?
Even Wirght Cyclones F-54 why not? Better than overused M-63/M62 or M-25 mid 1942. Even Old Polikarpov I-5 extra-old fighters were taken for new service that year.
From 1938 to end of March 1942 There had been 11,121 R-2600 'A' s built (1600hp and below) and 802 R-2600 "B"s built (1700hp). Given it's use in Western planes (1,308 A-20s built by the end of 1941, not all with R-2600s) and the usual procedure of allowing 33-50% more engines than airframes as spares there just aren't a lot of extra engines hanging about to send to Russia. The Cincinnati Plant (the largest aircraft engine Plant in the West, if not the world) was just coming on line with 443 R-2600s built in 1941. It would go on to build 25,680 R-2600s in 1944 alone out of a total of 54,048 R-2600s built at that plant but that isn't early-mid 1942 is it?
It's like for P-40's or B-20's, Marylands. I think there would have been much less of them without British/French commands.
Your first point "The R-2600 was rather optimised for bigger planes like Il-4 or Yer 2 in wich case it's size disavantage were less marqued" is quite true and that is were the west used the R-2600. In bombers and attack aircraft were it's size was less of a disadvantage.
No surprise...
Regards
Now, just a minor question - is that always so that engines from 1943-44 are better choice than those from 1941?
Yep.
Several things contribute to this.
It depends who for, thanks to the depression soviets baught nice engine, machine-tools and licences in mid-30ies at low coasts.8)2. The accelerated development of war time, especially in comparison to the lack of funds/time for most of the 30s due to the great depression.
A true problem rarely quoted, for countries that hadn't the US industrial/economical power. And a break for engines power evolution.3. The acceptance, in many cases, of War Emergency ratings (or what ever they were called by different nations) as a difference from what was acceptable in peacetime. In 1941 they were still trying to figure out how far they could press things. With the ramp up in production of aircraft decisions that affected the service life of engines (as in shortening them) means that you need that many more engines for the same number of aircraft.
And soviets too due to american efforts for installing full bright new 6 Eugène Coudry's cracking method refineries from 1943, and of course LL deliveries.4. For the Western Allies at least, the provision of better fuel allowed higher boost to be used without detonation. While in 1943-44 100 octane fuel was rated at (blended for and standardized) 100/130 lean/ rich this was by no means the case in 1940-41. US and British 100 octane were not the same and were measured at lean settings only. British fuel was better at rich settings but since there was no standard to measure against it varied from batch to batch and from refinery to refinery.
Note that high-octane fuel production is not only conditionned by technology, but mainly by your petrol deposit quality. No more than 30-35% from known soviet reserves were able to respund to that condition, and less than 1% exploited by germans. Still many years after ww2 rumanian Ploesti deposit was exploited by the east block, but never managed to give high octane fuel...
It's so why WEP, CP is limited on time...4b. Once you figured out what the higher allowable boost was from a detonation stand point you still had to get the engine to stand up to the extra loads (mechanical)and higher temperature loads. More fuel burned in a given amount of time meant more heat to get rid of.
Moreover you did not have in 1940 non destructive control methods (NDC) for engines with heatscopy, magnetoscopy, ultra-soundscopy etc...5. General march of progress again, even a few years at that time could make a difference in materials like steel and aluminum alloys or bearing materials. Up until just before WW I Aluminium, from a structural stand point, was regarded as little better than solidified dirt.
In fact, studies on correcting heat and weak points were systematically and statistically made on W-Off and damaged engines. And very progressively corrected.
So the same engine in 1940, was not the same in 1945.
Regards
(about newer engines being better than old)
Yep.
Those top-performers did have had a major shortcoming though - they were not available in 1941.
I would say that the IL-4 comparison is a little bogus though. The M-88 engine had less power than an R-1830. The R-2600s certainly had the power to lift much more fuel than the M-88 engines but perhaps the airframe couldn't handle the increased weight.
Very true, but the numbers do show the penalty of the R-2600. Even stuck in a LA-? airframe it is only 15-20mph faster than a P-40. Sticking it a larger, heavier American airframe means the speed difference would be even less.
The problem with the R-2600 in it's early forms was that it was a 1250-1400 HP engine that was allowed to run at 1500-1600hp for 5 minutes for take-off. Sort of a WEP setting. The engine had no reserve left to be boosted any further without modifications. Combine that with it's modest supercharger and it really dosen't look that good against the Allison. The 1600vs 1150 at sea level drops to 1400 at 11,500ft vs the Allisons 1150 at 12,000ft. About 44% of the HP advantage disappears by 12,000ft and you are stuck with the weight and drag. Or to put it another way, an increase of about 22% in power at altitude might not have been worth the weight, drag and fuel burn.
I was making the response with all the numbers, power-to-weight ratios, availability dates etc, but my best sentence is this (for this topic): I agree that we disagree
I was making the response with all the numbers, power-to-weight ratios, availability dates etc, but my best sentence is this (for this topic): I agree that we disagree
I know we disagree
For the 1700hp version 443 were delivered in 1941, 241 of them in the last 2 months of the year.
This rather limits the R-2600 to the 1600hp version for 1940-41 what ifs.
The 1600hp version used an aluminium crankcase and the 1700hp version used a steel crankcase so it is not a simple "tweak" to get the extra 100hp, or the extra altitude capability of the 1700 version. While 147 "B" engines (the 1700hp ones ) were built at Patterson, it was basically Patterson produced "A" seres engines (1600hp) and Cincinnati built the "B" series engines.
Power to weight ratios are good but for speed you need power to drag (or more properly, thrust to drag)
While power to weight is a rough indicator of climb it is the power available after you subtract the power needed to fly at best climbing speed which is usually the the speed that has the least drag. Flying slower actually needs more power because the drag is higher due to the increased angle of attack. Increasing the drag of an airplane slows the rate of climb even if the power to weight ratio stays the same.
There is more to it than that but estimating climb rates is tricky.
R-2600 powered fighters were certainly possible, it's just that they may have shown little improvement over either existing fighters or too little improvement to be worth switching production lines over and then switching them again when the R-2800 became available.
There is little doubt that the R-2800 was the engine of choice with Ford being give 14.7million dollars in Sept of 1940 to build a new factory just for the R-2800. This is with in a month of Packard signing up to build Merlins and about 15 months before Pearl Harbor.
Grumman had started working on an R-2600 powered fighter based on the F4F in 1938. It was called the G-50 project. It remained a paper project for several years until the navy came looking for an "improved F4F".
Grumman had already concluded that a new airframe was needed to get the most out of the R-2600.
There may have been other "paper studies" by other companies. It would surprise me if there weren't considering some of the "paper" studies done on other airplanes ( a P-39 with the cannon ahead of the engine but with the pilot behind the engine) and as you have pointed out it was the powerful engine available at the time. Somebody must have done at least some back of the envelope doodling on such a concept.
Now did the lack of anybody actually cutting metal on an R-2600 powered fighter show official resistance to the idea or does it mean that the preliminary calculations didn't show any real advantage? Or a bit of both?
With a lack of wind tunnels in the late thirties (few, if any companies had their own) even accurate estimates were hard to come by.
as for a Jan 1942 and later what if:
This chart may be of interest;
http://www.zenoswarbirdvideos.com/Images/TBF/TBFEDOLC.pdf
Please note that while it is for an Avenger it is a 1700hp for take-off "B" series engine and it is about as good as it gets for R-2600 historically. Feel free to extend the 2600 rpm line to higher altitudes than shown.
No, it was plenty as en egg. Try to fulfill 3000 kg (4250 l) of fuel inside. It's why in the end of 1941 special extenal tanks from 70 to 345 l were usedThe problem with the IL-4 wasn't the size or volume, it was certainly big enough. The problem may very well have been the the Strength of the airframe.
The Il-4 (DB-3 F) airframe was less than 9% common, with the old one DB-3, and intended to be used at 12 500 kg overload. Moreover it was tested with M-81 engines in 1940, and several times with M-82 ones in 41-43, each time loosing it's strategical capacity. Range: 2540 km, as for a B-25 or Tu-2. Even without that, since that studies ware ordenned with american R-2600 and R-2800, it's because the aiframe was able to withstand the weight/power increase.No disrespect intended but an airframe designed for 950-1100hp engines and fuel and bomb load to go with it may not have been able to cope with 1600-1700hp engines ( about 600lbs heavier apiece BARE weight) and the increased fuel load without a major redesign or beefing up.
Trials proved that external tanks did not improved the radius, only the time it could fly to extra drag.Without increasing the allowable gross weight by several thousand pounds, you are correct, the re-engined plane could not carry enough fuel to go anywhere near as far while carrying the same amount of bombs.
Might be. It seems that 1800-2000hp engines were used on the english bomber.AN R-2600 powered Wellington or Whitley might have been interesting though
Regards
Had the real development started couple of years earlier, the F6F with turbocharged R-2600 would have been in service by the end of 1941.
Below XF6F-1 with R-2600.
Same could be said for many aircraft and engines including perhaps jets.
1. Grumman to start work much earlier than they did.
2-A. GE has to get the turbocharger act together a lot sooner. While the turbos were combat capable in 1942 (for the most part, troubles still lingered), Combat capable turbos in squadron service were an iffy thing in 1941.
3. Given the lead time needed for tooling up, decisions on which version of engine or airplane need to be made 1-2 years before planes get into squadron service.
Of course. This is a "what-if" -thread. I would have put the DB601 in a Mustang airframe to create a world-beater in 1941.
I think there were a lot of B-17's flying around in 1941 not knowing this. Consolidated P-30's with turbos were flying around mid thirties. USA was the leading country in this area.
No, what I am saying is that sometimes different models of the engine can take 1-2 years to design, develop and tool up for.Are you saying that the different submodels of an engine needed 1-2 years of design of an airframe, before they could enter service ?
For example the P-47 used R2800 -17,- 21, -58, -59, -61, -63, -77,- 77 versions (changing the turbo also). Russians changed the inline engined LaGG-3 to radial engined La-5 within months.
Was the R-2600 so much different ?