Experimental German planes

[davebender]

That's hardly surprising since the Me-262 was intended primarily to kill heavy bombers at high altitude. It's also why the Me-262 was so heavily armed.

 

[davparlr]

Jet engines take years to be developed. One of the principal issues is that You are dependent on a high altitude pressure chamber, which not only works as a climatic controlled pressure stand with a dynamometer but also as a wind tunnel to simulate the high speed of a jet engine. Otherwise the design process is limited on empirical tests with flighttesting under conditions approaching the theoretical considerations.

The German's may have had better facilities but it did not seem to reflect in the performance of their engines. I think the decision to focus on axial flow compressors was mistake. While the axial flow compressors certainly had the potential for better performance, as shown by the dominance of this type in present day applications, the time required to develop mature performance was considerably longer than for centrifugal compressors. Time the Germans did not have.

Without a doubt the Germans were significantly ahead of the Allies in regard to jet aircraft engine/airframe integration. The Me 262 was significantly ahead of the first efforts of the Allies. Both the P-59 and Meteor were apparently based on pre-war concepts of maneuverability over speed. Both maneuvered well but were much slower and realistically non-competitive with the German jet aircraft. Not until the P-80/Vampire development did the Allies catch up with German jet aircraft designs. In the past I have attacked Bell for basically incompetence in designing the P-59. However, later study has enlightened me to the constraints levied against Bell due to security including limited, if any wind tunnel testing or outside consulting.

However, this German advantage did not seem to apply the jet engine itself. Germans engines do not appear any more user friendly or reliable than allied engines. In addition, Thrust levels, while good to start with, soon were out distanced by Allied efforts and thrust to weight is comparatively poor. A comparison of engines operational in May, 1945, and those being developed at that time, is enlightening.

Flyable engines

German
Jumo 004 engine
Weight - 1585 lbs
Thrust -1980 lbs
Thrust to weight- 1.25
Axial flow compressor
Usage - Me 262, Ar 234, Ju 287, Go/Ho 229

BMW 003
Weight- 1240 lbs
Thrust- 1760 lbs
Thrust to weight ratio- 1.42
Axial flow compressor
Usage- Ar 234C, He 162

Allied

Derwent I
Weight -975 lbs
Thrust -2000 lbs
Thrust to weight - 2.05
Usage Meteor

Goblin Gn. 2
Weight- 1550 lbs
Thrust - 3102 lbs
Thrust to weight - 2.00
Centrifugal flow compressor
Usage – Vampire

GE J31-GE-5 engine
Weight 850 lbs
Thrust 2000 lbs
Thrust to weight ratio- 2.35
Centrifugal flow compressor
Usage – P-59

GE J33-A-11
Weight- 1786 lb
Thrust- 4000 lb
Thrust to weight - 2.24
Centrifugal flow compressor
Usage – P-80

Developmental engines
German

Jumo 012
Weight - 4410 lbs
Thrust - 6130 lbs
Thrust to weight - 1.39
Axial flow compressor
Status - Seems to have not been assembled

BMW 003C
Weight- 1240 lbs
Thrust- 1980 lbs
Thrust to weight ratio- 1.6
Axial flow compressor
Usage- Ar 234C, He 162
Not completed

HeS 011
Weight- 2094lb
Thrust -2700 lb
Thrust to weight - 1.29
Axial flow compressor
Status - Prototype only

Allied
Metrovick F.2/4 Beryl
Weight- 1750 lbs
Thrust- 3500 lbs
Thrust to weight - 2.0
Axial flow compressor
Status –Ground tested Jan. '45.

Nene
Weight - 1550 lbs
Thrust - 5000 lb
Thrust to weight- 3.23
Centrifugal flow compressor
Status - First run Oct. 1944.

Westinghouse J-30 (FH-1 Phantom)
Weight 705 lbs
Thrust 1550 lbs
Thrust to weight ratio 2.2
Status first run March '43
Axial flow compressor

GE/Allison J-35 (P-84 Thunderjet)
Weight 2500 lbs (estimated)
Thrust 3750 lbs (non-afterburning)
Thrust to weight 1.5
Status in development (P-84 flew Jan '46)
Axial flow compressor

From this comparison we can see that Allied engines had better thrust to weight ratios than the contemporary German engine and therefore the German engines were much heavier. The two engines of the Me 262 was almost 1400 lbs heavier than the equally powerful single engine of the P-80, a big going-in disadvantage. The already running and ready to fly Nene engine was 2860 lbs lighter than the 20% more powerful, but not yet run Jumo 012. It was also had two and a half times the thrust of the not yet built BMW 003C but weighed only 25% more. Compared to the already running prototypes of the HeS 011, the Nene had 85% more thrust but the 011 weighed 35% more.

While the Germans gambled on the potentially more efficient axial engines, their technology limitations and material shortages put them at an engine disadvantage in 1945 that would hamper their more advanced aircraft designs. I don't think the axial engines caught up with the centrifugal engines until the Korean War. Even then, the Mig 15 KV-1 engine was 1312 lbs lighter than the F-86's J-47 at the same thrust. With the more powerful engines, the centrifugal compressors could be buried in the fuselage, somewhat offsetting the advantage of the more slender axial engines.

It is also interesting to note number of different jet engines and variety of technology available to the Allies as compared to the Germans.

 

[delcyros]

GregP,

thanks for Your memo above. You raised some interesting questions. One of them beeing that the benefit of having proper test facilities did not reflect in performance of actual jet engines.
To answer this question, I suggest we need to settle about the qualification what is required to define "better". If the answer is thrust-weight ratio only, then I agree with Your contention that radial jet engines may offer more ease of design and production than axial jet engines in the specific 1944/45 timeframe under discussion.
However, I am not convinced that such an approach is entirely justified here. To be more precise, ease of operation is a very important criterium for early jet engines, with all the involved culprits. Neither the Dervent, Nene nor the J-31/33 had a good reliability record before fall of 1945. Problems outlined in Meteor-III and XP-80A trials record various problems, compressibility, surge, flameout under G-load and flameout at high altitude operation, rapid throttle changes and the warning not to restart the engines in flight have been mentioned as problems before beeing solved in the latter part of 1945 (in part thanks to analysis of the inflight behavior in proper BMW testfacilities at Munich).
It may also be mentioned that the standart JUMO-004B jet engine in service through 1943 and 1944 did not aim for maximum performance.
At the time of the start of the -004 development, there existed no suitable testfacility to test multistage compressors. The first two JUMO-teststands (one in Oberhausen/Bavaria and one in Dresden / Saxony) were not online before 1944. Anselm Franz, who later went to the US and there was employed as a specialist in the early jet engine program, defined the design goal of the Jumo-004 as following:
"In consideration of the novelty of the object, in order to guarantee as much as possible the greatest chance of success, it was deliberately avoided to aim for the maximum possible." -BMW on the other hand, did more careful layouts of the compressor and turbine, resulting in a superior, albeit delayed product, which then again, was found to be more efficient than the JUMO-004B (weight, fuel consumption, ease of operation, in buildt- overrew capability). Service lifetime of the BMW-003 was massively longer than any ww2 jet engine and larger even than many high performance piston engines of this period (200 hours as opposed to 20 to 30 usual). The over 6000 produced Jumo-004 units confirm the validity of the far sighted approach of Anselm Franz.

I must agree that centrifugal units would perhaps be a better solution than axial ones. But research in Germany was dedicated primarely to axial units. Some of the data proposed by You require correction.

The BMW-003 used by the He-162A was the BMW-003E variant and developed 930 kp (2050 lbs) max at 30 sec. overrew. The long lifetime of the BMW-003 made it the first engine to employ an overrew capability. Thus, the thrust to weight ratio was closer to 1.65 for a flyable engine in this case.
One jet engine, which is missed in Your list is a very interesting design by Daimler Benz. The DB-007 (axial compressor, single stage axial turbine with turbine blades cooled by partial air bleed). It was the first dual flow, low bypass ration jet engine and run on the testbench in 1942. The amount of thrust developed was 2,530lbs by 1943 at very low specific fuel consumption. DB was ordered by the RLM in 1943 to discontinue the program and start a much lager design, the DB-016 (9 stages axial compressor, two stages axial turbine). The He-S011 was in the air by 1945 with various prototypes running.
Another one developmental, which missed Your attention is the BMW-018. The BMW-018 is similar in timeframe to the RR NENE and developed similar levels of thrust, albeit at higher weight. A single prototype was completed and detroyed in an air raid oct. 1944, a He-130E was reerved as a flying testbed for the engine. Östrich, who lead the BMW development program went to France and continued his work, with the different but based upon his experiences laid out ATAR-101.
Finally, the more important developmental jet engines, which at least have been testflown in ww2 were the more improved, variants of the BMW-003D and the afterburner fitted JUMO-004(-C -E). The BMW-003D had a rating of 1100kp (2424 lbs) dry. An afterburner fitted BMW-003A/-E was also under consideration (1050 kp without overrew, 1180kp with), an rocket boosted BMW-003R equipped several Me-262C pre production units. This afterburner fitted BMW-003 later was produced in the SU under the designation RD-20F along with non-afterburner fitted RD-20´s (thrust weight ratio: 1.87:1 without overrew).
The afterburner fitted JUMO-004C was only a prototype, the -E version was intended to replace the 930kp developing JUMO-004D which was in mass production at the end of ww2. The -004C developed already 1200kp on the testbench in 1944 (thrust weight ratio: 1: 1.65).
I remain sceptical that the HeS011 would soon enter mass production. It was still a developmental engine by wars end, which didn´t met all requirements. The application at wars end was the -004D with 930 kp static thrust and the BMW-003A/E with similar power at overrew.
The initial stop gap measure to improve performance was fitting of afterburner equipment to the JUMO-004, followed by a replacement with a second generation jet engine.

While the Germans gambled on the potentially more efficient axial engines, their technology limitations and material shortages put them at an engine disadvantage in 1945 that would hamper their more advanced aircraft designs. I don't think the axial engines caught up with the centrifugal engines until the Korean War. Even then, the Mig 15 KV-1 engine was 1312 lbs lighter than the F-86's J-47 at the same thrust. With the more powerful engines, the centrifugal compressors could be buried in the fuselage, somewhat offsetting the advantage of the more slender axial engines.

Possible. Though most of the challanges had been sorted out by these early axial jet engines with film cooling and hollow blade cooling technologies invented. Thus, it´s likely that more improved engines would have followed suite at a more rapid pace than in the real world post-war history. Correspondingly, the rapid achievements attained by Britain, the US and SU -in part caused by the gathering of expertise and proper testing facilities from german war bounty is less likely to occur. The relationship is dynamic, not static.

 

[cimmex]

good info,thanks

 

[J dog]

yes this is all very helpful and not all of this I knew. Most of it yes but some of it I had mixed up and this helped thank you.

 

[delcyros]

The Me 262 is placarded at 540 mph TAS (869 kph). The Stormbirds boys who built the new-build planes used EXACTLY the same airframe, airfoils and aerodynamic design. The only real difference was the stormbirds planes had main landing gear taken from a Grumman S2F, wood guns with weights for CG, modern engines (limited to wartime stock thrust levels ... if you fly by the POH), and updated avionics. They were so accurate, Messerschmitt issued them consecurive work numbers from the end of the Me 262 serial line!

There was a letter on the wall from Messerschmitt in Germany (on Messerschmitt letterhead) stating the wartime planes were placarded at 540 mph TAS ... any faster and you were a test pilot. So all the new-build planes are placarded at 540 mph, too, without exception. I saw four different cockpits when I was there and all had the same speed redline. I will not debate the placard limit. The limit was set by Stormbirds with consultation from Messerschmitt, and I believe them. So do the pilots of the new-build planes. They have to sign a promise to follow the limits before any of them can fly one of the birds if the insurance is to be in effect.

Ah, I understand where this idea comes from, GregP. Thanks for outlining Your reasoning. Placecarding has limited relation to top speed. What MEsserschmidt did was to issue a Mach warining in the airplane. Since it hadn´t a Mach counter the placecard was issued, referring to MACH 0.81 (at >11,000m altitude). This is limiting Mach, not maximum or crit MACH, which was MACH = 0.86 according to Prof. Messerschmidt. The Mach number was related to density of the atmossphere and at lower altitudes, the Mach number is higher indeed.
Placecards were issued for varying reasons to all german A/C. The Bf-109 had a placecard at 650 km/h TAS, that doesn´t necessarely mean it couldn´t by design exceed 650km/h TAS.
The top speed of the Me-262 has been extensively tested by the Luftwaffe and all serially produced planes had to undergo Luftwaffe acceptance top speed trials. Hans Fay was after the end of ww2 interviewed on performance acceptance trials and he metnions that the minimum of acceptance was 830km/h at full throttle (without specifying altitude).
http://www.zenoswarbirdvideos.com/Images/Me262/ME262PILOTDEBRIEF.pdf
He tested ca. 50 serially produced Me-262 and only two were rejected, albeit not for lacking top speed but because of structural deficits.
For sake´s luck, I have the result of the performance trials of the average 1944/5 Me-262A with JUMO-004B from acceptance trials of a total of 125 serially produced Me-262A1 dated to february 1945, resulting in a mean of 843 km/h at a specified altitude of 800m (slightly higher than the 830km/h quoted by Fay):

Similarely, we have several performance trial data for the P-80A in the timeframe 1946 and 1947:
http://www.wwiiaircraftperformance.org/p-80/P-80A-85044.pdf
http://www.wwiiaircraftperformance.org/p-80/P-80A-85462.pdf
http://www.wwiiaircraftperformance.org/p-80/P-80-85123.pdf
http://www.wwiiaircraftperformance.org/p-80/P-80A-85075.pdf

The results of these performance trials question the validity of 560mph top speed often quoted for the P-80A. At least in the two years after end of ww2, the P-80A was unable to match this kind of performance. The graphical plot of the above performance trials is to be shown here:

Note that the fastest P-80A speed recorded is that of a december 3rd, 1946 performance trial with a specially modified P-80A with high speed nose and clipped wings, which yielded a top speed of 562 mph at 2700ft (excluded above). This is not a combat airplane -it´s a racing A/C. The fastest speed of a normal P-80A is 548 mph albeit with specially treated surface (dec. 1946). Specially smoothed paints with grey finish to attempt a smooth seal of all joints was never utilised in operational P-80A. the average speed of production P-80A is definetely lower than 560mph and compares well with the average speed from acceptance trials of the Me-262 referenced above:

I cannot see a distinct advantage for the one or other given that variances between individual trials reported for these A/C easily exceed the 10 to 15mph speed differences of the mean curves.
But keep in mind, this is late 1946 developmental state of the P-80A vs late 1944/early 1945 developmental state of the Me-262A -a developmental advantage of roughly one and a half to two years in advantage of the Lockheed P-80A. One to two years is a massive time advantage in the 1944 to 1947 timeframe and -at least in my mind- shouldn´t be left uncommented.
If You want to make a realistic asessment, You may add in proposed and already accepted improvements in the Me-262A design process, f.e. tail changes and windscreen inclination to improve crit Mach and controll issues at high Mach number as well as the fitting of JUMO-004E, both of which were to be seen already in mid 1945 produced Me-262A:

-the most notable and urgent effect was to adress the controll freeze encountered in high Mach numbers (high speed wind tunnels paid off) -Note the term "die Verbesserung der Oberflächengüte ist nur soweit berücksichtigt, wie sie für die Serie durchführbar und in Vorbereitung ist". It is important to stress that these changes were already prepared in mass production of the Me-262A jet fighter by the time this report was issued on february 23rd, 1945.

The fitting of new tail surfaces and slight improvements already gives the -262A a light advantage over the P-80A in general, which becomes very recognizable with improved JUMO-004E jet engines at all altitudes. The dry thrust of 980kp (+10% thrust over the -004B) is referred to here (Kurvenblatt 109.004-2006.14 from january 1945), not the reheat afterburner thrust of ~1200kp.

The USAF X-Plane series investigated a LOT of planforms and airfoils and configurations, and would have done so with or without German data. With it, we simply didn't have to investigate that particular data. Ditto the experimental US Navy planes, like the Douglas Skyrocket series and others.

Agreed 100%. There is no way to support the claim that swept wing technology wouldn´t be adopted by the allies. The technology was required to engage the Mach barrier. It saved time, to get these data and proper testing procedures but principially it should have been developed at about this timeframe.

 

[GregP]

Hi Delcyros,

Nice post, but I seriously wonder why anyone would test a P-80A in the 1946 - 1947 timeframe. By that time the P-80C was available as was the redoubtable F-86 Sabre (first flight October 1947) and the Republic F-84 Thunderjet (first flight Feb 1946). Perhaps the P-80A all they had. Were the charts with or without drop tanks? Also, I see the tests in the second link were run at 11,500 rpm instead of the 11,800 rpm maximum allowed, apparently to study the effects of the aircraft surface finish.

According to the early jets pilots we have given talks at the Planes of Fame, the Me 262 was not as fast as a P-80A. That encompasses about 30 former jet pilots of both German and American nationality, so I'll remain skeptical and simply say that during the war, they never met each other as we all know. After the war, we have testimony from quite a cross-section of test pilots that disagree with the contention that the Me 262 was faster than the P-80A. The chart with the canopy on it shows two lines and I can't tell what is what since I do't read German and even the legend is missing. The slower line maxes out at about 870 kph, which is 540 mph.

That tells me that maybe the slower line is the service limit and the faster line is the potential, again, I can't tell. The P-80A had a similar chart with service limts and potential, too, so you should compare apples to apples and look at the max potential for the P-80 as well as for the Me 262. But by 1946/7, there were faster planes avaiable than the P-80A. Not so for the Me 262 since development ceased with the end of the war.

I'm sure it had potential, but I'm also sure the layout with the engines out under the wings was NOT optimal for roll and that the maneuevrability of the Me 262 was not as good as for early jets with engines in the fuselage (or the Meteor), though the armament was outstanding. If development had continued, I'm sure it would have been competitive with the other early twin-jets with engines out on the wing that made it inro production, and was superior to the Meteor in speed and armament, though not in maneuverability or climb depending on conditions.

Once the F-86 Sabre and MiG-15 were in service, the Me 262 would have been a second-line aircraft even if development had continued. That happened, coincidentally, about the end if 1947, right when your charts were apparently developed.

The P-80 series and the Me 262 developments would have been good opponents for one another particularly if the P-80 had changed to cannon armament, and I think that if they had ever met in combat for more than a few days, it might have happened.

 

[delcyros]

Hi GregP,

thanks again for Your memo, which helped me understanding You. You asked why anyone would test the P80A in the 1946 to 1947 timeframe. The answer is that the RAF had an instrumental interest to explore the aircraft, which had not yet passed all of it´s evolutions and trials in a testing environment which was delayed. The following data comes from MEMORANDUM OF FLIGHT TEST DIVISION and may held to answer Your questions.

REPORT SERIAL NO.TSFTE-2009, issued 29th of august 1946.
PERFORMANCE TEST OF THE LOCKHEED P-80A1 AIRPLANE, AAF No. 44-85044

I. INTRODUCTION
Flight tests were conducted on the P-80A1 Airplane, AAF No. 44-85044 at Wright Field, Dayton, Ohio between january 1946 and july 1946. The original request for these tests was made in May 1945 on P-80A1 airplane, AAF No. 44-84995, however, this airplane was assigned to another project before accomplishing any part of the included results. (emphasize by myselfe)

Therefore, we have to conclude from the serial number that this airplane comes from the original batch of the first 345 aircraft of this contract (serials 44-84992 to 44-85336) all designated P-80A-1-LO and delivered before Sept. 1945. Note that these P-80 were propelled by a 3850 lb.s.t. rated General Electric J33-GE-11 or the similar, but Allison manufactured J33-A-9 turbojet, not by the 4000lbs version (J-33-A-17), which drove P-80-A5-LO airplanes (serials No. 44-85337 to 44-85941 and 45-8301 to 45-8262) and 218 were delivered from august 1945 to mid 1946. This latter batch had the engines cleared to brief overrew and 11,800 rpm.

I return to the report:

Tests were made in order to obtain performance at two configurations, clean, and with two 160 gal. wing tip tanks. From January 1946 through July 1946 thirty-six flights were made by Fighter operations Section Pilots with Captn. M. L. Smith flying most of the tests.

In Section II follows the summery. In the comparative tables I showed above, of course I excluded the trial data for wingtip tank records as they were not indicative for a clean P-80A1 airframe. The missed out data for them are (P-80A-1 incl. 2 x 160 gal drop tanks, all on J-33-A-9 engine unless otherwise stated):
SeaLevel: 494mph (510mph without drop tanks and J-33-GE-11 engine)
10000ft: 512mph (518mph without drop tanks and J-33-GE-11 engine)
20000ft: 513mph (520mph without drop tanks and J-33-GE-11 engine)
25000ft: 507mph (534mph without drop tanks, 519mph without drop tanks and J-33-GE-11 engine)
30000ft: 497mph (526mph without drop tanks, 515mph without drop tanks and J-33-GE-11 engine)
35000ft: 485mph (512mph without drop tanks, 507mph without drop tanks and J-33-GE-11 engine)
40000ft: 472mph

Thus a 1945 manufactured batch#1 P-80A1 in clean fighter configuration ranged in speed between 524 mph at 15050ft and roughly 534 mph at 25000ft
Interesting is perhaps section III.
III CONDITION OF THE AIRPLANE RELATIVE TO TEST.
The Airplane was flown in its normal fighter configuration, smooth paint finish[note*], an with all standart equipment in place. A photo-recorder and ballast located in the nose of the airplane substituted for the weight of ammunition for the six 0.50 caliber machine guns. The gunports were open, the gun muzzles and blast tubes were covered and taped.

The gross weights for the two configurations were as follows: clean configuration, the average starting gross weight was 11,560 lbs. which included full internal fuel of 435 gal. and 3 gal. of engine oil at a c.g. position of 31.3% M.A.C.

[note*]: Early P-80As had a overall light grey finish which was used to seal all skin joints. This finish proved to be too hard to maintain in service, and was deleted in favor of a natural metal finish. With filler and paint, these aircraft prooved to be faster than without.
and:
VIII. CONCLUSIONS.
1. The performance report is representative for production P-80A-1 airplanes.

According to the early jets pilots we have give talks at the Planes of Fame, the Me 262 was not as fast as a P-80A. That encompasses about 30 former jet pilots of both German and American nationality, so I'll remain skeptical and simply say that during the war, they never met each other as we all know. After the war, we have testimony from quite a cross-section of test pilots that disagree with the contention that the Me 262 was faster than the P-80A.

I fear that the number of test pilots, who have flown both, Me-262A1 and P-80A1 in fair condition is rather limited as Me-262A pilots didnt flew any P-80A1 (perhaps later derivates with waterinjection) and vice versa, only two P80A pilots flew the Me-262A as it´s known. Conventional wisdom is that the P80 Shooting Star was good for 560mph but people mean the late models not the early ones when they say this. Thus, I would expect a reception phenomen here. The fact that P80A-1 were in the latter part of 1946 refitted to P-80A-5 standart with more powerful, 4000lbs jet engines and boundary layer seperation at the air intakes adds to the confusion and the performance of the -A5 subvariant is considered to be representative for all P-80A aircraft. Pilots are interested and they do read about other planes. However, the P80A is credited with more speed in literature than it was able to attain, which is also the content of the only comparison trial between both A/C which remained long classified for this reason. I personally have never seen this report, which claims that the -262 is faster and better climbing we know some results but not the details, which would be important to know.

The chart with the canopy on it shows two lines and I can't tell what is what since I do't read German and even the legend is missing. The slower line maxes out at about 870 kph, which is 540 mph. The P-80A had a similar chart with service limts and potential, too, so you should compare apples to apples and look at the max potential for the P-80 as well as for the Me 262. But by 1946/7, there were faster planes avaiable than the P-80A. Not so for the Me 262 since development ceased with the end of the war.

Entirely correct. The thin line is the first graph reproduced (=the mean of 121 serially produced Me-262A in performance trials) in the 2nd state of Me-262A. The 2nd state shows the potential gain of already ordered and prepared improvements in mass production (state february 1945!) with regard to more inclined front window and controll surface modifications.
The comparison -if intended to be an apples vs apples one should compare the mean of both worlds. That is the mean of P80A1- and -5 airplanes (from 1946 trials roughly 535 mph for this airplane at optimum altitude) not with that of the Me-262A1 (from 1944 performance trials, roughly 540mph for this airplane) but with the proposed and already agreed on mass production upgrades. The 1945 manufactured P80A (from trials 1946) was not distinctly faster than the 1944 manufactured -262A (from trials 1944 to january 1945). It was slightly ahead at altitudes lower than 12000ft and slightly behind at higher altitudes. However, this P80A was still distinctly slower than the proposed serially manufactured -262A from 1945 with improvements added, which it had little opportunity to benefit from because the production ceased in april 1945.

Once the F-86 Sabre and MiG-15 were in service, the Me 262 would have been a second-line aircraft even if development had continued. That happened, coincidentally, about the end if 1947, right when your charts were apparently developed.

I entirely agree. The limit of usefulness for the Me-262 was reached at a certain point and You correctly pointed out the engine position. It certainly would still have been useful in the night fighter role and as an experimental object to challange the MACH barrier -the V9 explored this issue wrt to controll freeze of the tail controll surfaces, another Me-262A with new and 35 deg swept back wing of HG-II standart -Werknummer 111538- was buildt but damaged in a taxiing accident without ever going airborne. The intention to explore MACH 1.0 with these airplane -along with other projects is recognizable. But as a dayfighter, it would have been replaced by more dedicated swept wing designs, such as either a swept wing He-162, the Ta-183, Hs-P135 or the Ju-EF128 at one point or another.

 

[Aozora]

A really interesting discussion: butting in slightly regarding British research and interest in advanced concepts: I have been digging through the Flight magazine article database and have found some interesting articles on jet turbine powered flying wings (13 May 1943), and a critique of German swept wing research (17 and 24 October 1946).

 

[GregP]

Hi Delcyros, Nice reply; I like your posts. As a former aeronautical engineering student (only made 3 years before switching to electrical engineering), I think the Me 262 did, in fact, have good development potential, but seriously doubt it would ever go supersonic. We studied that in school in 1969 and concluded it would not go supersonic ever. The report floating about claiming that one did in WWII is conjectural vapor ... take a standard Me 262 and test it in a real wind tunnel with real data acquisition. The data are fairly plain.

Nevertheless, I think the P-80 line was generally superior to the Me 262 except in armament. Just a personal opinion. We also have heard from 3 - 4 pilots who flew both the Me 262 and P-80 planes in various presentations. We have one on the first Saturday every month, always on a different plane or series of planes. The rest of the approximately 30 or so flew one or the other and reported their performance as observed, usually by reading from flying notes taken at the time by themselves. One flew the Me 262, He 280, Me 163, and He 162! He was an American of German origins who had been trapped in Germany when the war broke out, and was drafted into the Luftwaffe! His story was VERY interesting. He delivered jet aircraft from the assembly line to the front units. A truly interesting fellow! .. and with a good sense of humor.

I think that since the 1944 / 1945 P-80 and Me 262 never met in the real sky; this bantering is interesting but fairly useless; it never happened. If they HAD met, it would have been in the 1946 or 1947 timeframe since they never met in the REAL 1944 / 1945 timeframe. By that time, BOTH would doubtlessly have been faster and better developed ... but the results are pure conjecture. I have no real desire to choose one victor or the other since it never happened, but the topic IS an interesting one to me on a theoretical level.

In the real world at the Planes of Fame Museum, we find the reports from the war on both pistons and jet fighters were mostly tainted with national bias. The real planes are not really as stated in the reports, and all have their strengths and weaknesses. We really like our MiG-15 bis as well as the Sabre. All the pilots would choose the Sabre except one, who loves the MiG. Ditto the pistons. We have a LOT of experience with them at 250 - 300 mph; and some at faster speeds, usually in dives or aerobatics. Specific performance points are not always as implied by the reports of the day, and the people who flew them back then remember the characteristics as WE find them to be when flying them today.

That probably colors my viewpoint ...

 

[GrauGeist]

Just for the record, at speeds above Mach .86, the Me262A-1a would begin a nose-down attitude, a condition that the pilot would not be able to correct unless he was able to reduce the airspeed. After the war, the British and Russians also noted this effect when they were testing airframes for Mach capabilities.

It was certainly not capable of transonic flight.

 

[GregP]

Great revolving pics in your sig, Garugeist! I'd like to make the acquaintance of some of the frauleins ... escepially the ones serving beer.

You know, the fabled "coffin corner," or nose-down tendency if any faster than the limiting Mach number ... I have always wondered if the nose down could have been avoided by rolling inverted and turning the nose-down into nose-up. Perhaps not ina Learjet, but maybe in an actual fighter.

The early Lears had a real bad coffin corner ... 2 - 3 faster and you were into Mach Tuck (the "nose-down" pitching moment) and 2 - 3 knots slower and you would stall; speed control was vital, to say the least. The newer Lears have 20 - 35 knots of cushion at max altitude, so they're pussycats by comparison.

 

[GrauGeist]

Well Greg, it seems like inverting would be a solution for that condition, but if you're in that zone, chances are your control surfaces are going to be sluggish or non-responsive. You may be able to "break" it by pushing foreward on the stick but I would think that one would have a better chance by bringing the engines to an idle and trying to bleed off speed until controls are responding again (this is of course if you have the time altitude, otherwise Jesus better be your friend).

 

[michaelj_warbird]

Ok Let's say the Germans won WW2 and the Korean war still happened no matter any world changes after that. Would the German experimental planes or fastest planes be capable of taking on MiG -15s or Sabres? This is not me saying that the Germans could win the war though this is just me asking a question. Please comment and please make things appropriate and respectful towards others opinions!

great question.

I'm new to this web site by the way. It's nice to be here, among fellow aviation enthusiasts !

hmm, it depends on what the germans would have done. Would they have been satisfied to have taken all of europe and russia? I think so, probably. If they would have really won,, well they did have plans to attack the usa, so they might have done that, and , they were allied with japan, so maybe they would have formed a world alliance with japan and formed a kind of super country with japan. but knowing germans, they would want it to be a german super country/continent and not totally be combined with japan.

any way, hmm, well if they would have really defeated russia, which they were engaged with, then they would have had to really beat russia, meaning that russia would not have even existing as russia any more, and never would have made korean war-era migs. But instead russia would have fallen under the third reich's command, and it would be a part of the third reich. so the real question is: would the cold war have been between russia and usa, as it was. and the answer is no, because russia would be part of the third reich, and usa possibly also.

so thats a complicated question, (it's a what if question) but anyway , many countries drew upon what was done with the me-262 and other advanced designs that the germans developed, and integrated it into their own, for the next generation craft.

hmm , another point would be, what if the germans had not made such advanced craft during ww2. then what would the korean war have looked like. and we know the answer to that. probably there would be more piston engined planes, and some less advanced jets , and everything would have slowed down, into the 70's and 80's etc, so we would not have had as advanced jets today as a result. course we probably would not have gone into space at all.

 

[Njaco]

I have to hand it to you guys for having an informational and respectful conversation without any cr@p. Love it.

The earlier post by Davlpar about the differences of a axial and centrifugal engine (and the relation to the Me 262) is spot on to just about everything I've seen or read about jet engines. The follow-up information by everyone else is making this a really great thread to read through.

 

[davparlr]

GregP,

thanks for Your memo above. You raised some interesting questions.

It's okay to address your response to Greg instead of me when replying to my post when it's negative, just get my name right when it positive!

I suggest we need to settle about the qualification what is required to define "better". If the answer is thrust-weight ratio only, then I agree with Your contention that radial jet engines may offer more ease of design and production than axial jet engines in the specific 1944/45 timeframe under discussion.

Thrust-to-weight or power-to-weight has always been a critical parameter for aircraft engines. I don't think you can deny that the 1400 lb difference between the Me 262 and the P-80 would not make a significant impact to performance to either plane.

However, I am not convinced that such an approach is entirely justified here. To be more precise, ease of operation is a very important criterium for early jet engines, with all the involved culprits. Neither the Dervent, Nene nor the J-31/33 had a good reliability record before fall of 1945.

I don't think any jet engines had good reliability during this period. I don't think the German engines had any special claim to reliability (MTBF), engine replacement availability, operator friendliness, or any other criteria related to overall jet operations.

Problems outlined in Meteor-III and XP-80A trials record various problems, compressibility, surge, flameout under G-load and flameout at high altitude operation, rapid throttle changes and the warning not to restart the engines in flight have been mentioned as problems before beeing solved in the latter part of 1945 (in part thanks to analysis of the inflight behavior in proper BMW testfacilities at Munich).

Like I said, I think the German engines had their share of problems like difficulty to start, flame-outs with rapid throttle movement, etc. By the way, how did they test for flameouts under G-load? Did they have a wind tunnel mounted on a centrifuge contained in a pressure chamber? Now that would be something to see.

It may also be mentioned that the standart JUMO-004B jet engine in service through 1943 and 1944 did not aim for maximum performance.

I suspect all the engines mentioned went through the same process of conservative design. They were not fools. Only the acceptable risk was a variable and we do not know what that is on most of the engines.

Some of the data proposed by You require correction.

This doesn't surprise me since I don't have a lot of resources in engine development.

The BMW-003 used by the He-162A was the BMW-003E variant and developed 930 kp (2050 lbs) max at 30 sec. overrew. The long lifetime of the BMW-003 made it the first engine to employ an overrew capability. Thus, the thrust to weight ratio was closer to 1.65 for a flyable engine in this case.

The only references I have shows 1760 lbs, but I can't say they are unimpeachable.

One jet engine, which is missed in Your list is a very interesting design by Daimler Benz. The DB-007 (axial compressor, single stage axial turbine with turbine blades cooled by partial air bleed). It was the first dual flow, low bypass ration jet engine and run on the testbench in 1942. The amount of thrust developed was 2,530lbs by 1943 at very low specific fuel consumption. DB was ordered by the RLM in 1943 to discontinue the program and start a much lager design, the DB-016 (9 stages axial compressor, two stages axial turbine).

Apparently the 007 did not exist in 1945. I have no information on the 016.

The He-S011 was in the air by 1945 with various prototypes running.

I think the aircraft applications of the HeS 0011 was flying test bed flights which means that they were more advanced than ground test but not yet fully qualified for military application.

Another one developmental, which missed Your attention is the BMW-018. The BMW-018 is similar in timeframe to the RR NENE and developed similar levels of thrust, albeit at higher weight. A single prototype was completed and detroyed in an air raid oct. 1944, a He-130E was reerved as a flying testbed for the engine. Östrich, who lead the BMW development program went to France and continued his work, with the different but based upon his experiences laid out ATAR-101.

I think the program was a mess in 1945, if it existed at all. However, the BMW work certainly turned into a modern turbojet engine in France, one of my criteria for the evaluating the viability of war designs. Still, I doubt the engine met the contemporary allied designs in thrust and thrust-to-weight.

Finally, the more important developmental jet engines, which at least have been testflown in ww2 were the more improved, variants of the BMW-003D and the afterburner fitted JUMO-004(-C -E). The BMW-003D had a rating of 1100kp (2424 lbs) dry. An afterburner fitted BMW-003A/-E was also under consideration (1050 kp without overrew, 1180kp with), an rocket boosted BMW-003R equipped several Me-262C pre production units. This afterburner fitted BMW-003 later was produced in the SU under the designation RD-20F along with non-afterburner fitted RD-20´s (thrust weight ratio: 1.87:1 without overrew).
The afterburner fitted JUMO-004C was only a prototype, the -E version was intended to replace the 930kp developing JUMO-004D which was in mass production at the end of ww2. The -004C developed already 1200kp on the testbench in 1944 (thrust weight ratio: 1: 1.65).
I remain sceptical that the HeS011 would soon enter mass production. It was still a developmental engine by wars end, which didn´t met all requirements. The application at wars end was the -004D with 930 kp static thrust and the BMW-003A/E with similar power at overrew.
The initial stop gap measure to improve performance was fitting of afterburner equipment to the JUMO-004, followed by a replacement with a second generation jet engine.

All of these advances were pushing performance up on the axial flow engine but were still behind the performance of the J-33 in the P-80 and well below the British Nene engine, T/W ratio of 3.23. I ignored afterburning performance as I consider it a trivial engineering effort compared to the core jet engine design and was relatively easy to implement. Even the very early L-1000 jet engine by Lockheed discussed thrust augmentation by injecting fuel into the turbine blades. Also, the Nene offsprings in the P-80 and Mig-15 added afterburners to make the F-94 and Mig-17 (which was formidable even in the Vietnam War). In addition, the early jets were notoriously big consumers of fuel and afterburners are voracious, there use would significantly impact any airborne operations.

Possible. Though most of the challanges had been sorted out by these early axial jet engines with film cooling and hollow blade cooling technologies invented. Thus, it´s likely that more improved engines would have followed suite at a more rapid pace than in the real world post-war history. Correspondingly, the rapid achievements attained by Britain, the US and SU -in part caused by the gathering of expertise and proper testing facilities from german war bounty is less likely to occur. The relationship is dynamic, not static.

The end of the war certainly dried up military spending in the West slowing down any development. Had the war continued competitively, it is likely that the aviation development available in 1949-50 would be available in 1946-47 and it would have continued to see-saw in technology as it had been doing, excluding any nuclear events. Due to vast resources the Allies were quite capable of reacting quickly, usually within months of the introduction of new technology. And they already had advance engine development in the Nene and J-33, several programs going in axial engines some of which will evolve into great engines, theoretical knowledge on swept wing designs. The Germans certainly had a significant advantage in aerodynamic theory, jet aircraft integration capability (mostly eliminated with the advent of the P-80/Vampire) and test facilities, as you have pointed out, but, in general, like I said the Allies had a huge capability to respond.

 

[Jack_Hill]

@Davparlr
Hi,
"I don't think the
German engines had
any special claim to
reliability (MTBF),
engine replacement
availability, operator
friendliness, or any
other criteria related to
overall jet operations."
As far as Me-262 and He-162 are concerned, I don't think it's true.
Quick field engines replacements where possible and operator friendly, because designs planned it from the very start of the projects.
Brand new engines were massively available(brand new a/c too).
From the fall of '44 until capitulation, Germany was kind of "open bar" for parts and a/c.
Corruption and disorganisation were the rules.
Nice thread, educative, love it.

 

[DerAdlerIstGelandet]

If they would have really won,, well they did have plans to attack the usa, so they might have done that

Germany did not have a desire to invade the USA. Nor did they have plans to do so. What plans do you speak of?

 

[GrauGeist]

The German leadership considered and evaluated bombing the U.S. mainland to demoralize the citizens in the hopes that it would pull the U.S. out of the war.

 

[DerAdlerIstGelandet]

The German leadership considered and evaluated bombing the U.S. mainland to demoralize the citizens in the hopes that it would pull the U.S. out of the war.

Yes, I know that. I have a great book on the subject. There however where no plans to actually bomb the US drawn up. Nor was there a desire or plan to "invade". Even Hitler knew that if sn invasion of England was impossible, the US was out of question. I highly doubt Hitler even would have wanted that. His plans were always to the east.