Me-262: Future in light of engine development

[Shortround6]

A lot of aircraft and engine programs slowed down considerably after the war ended. Granted this did sometimes give extra time to figure somethings out but it also could mean higher expectations, in peace time they may have wanted not only more hours between overhauls but more hours between major failures (which is not the same thing).

Please read the page so kindly provided by Neil Sterling in post#17, under the contracts for the Meteor I/II. Of the 300 aircraft in the initial contract the exact type and number of each type changed several times but final completion numbers were 20 F.Is, 230 F.IIIs and 40 F.4s with the F.4s being delivered between March and Dec of 1946. The next contract was for 100 Meteor F. IIs (Goblin engine) but they were completed as F.4s from Dec 46 to Jan 47 (50 a month? or misprint?)

With 140 aircraft on hand (?) I have no idea why they didn't enter service until 1948.

Please note that a contract for 300 Meteor F.IIIs was canceled in Sept of 1945. Rapid deployment of large numbers of planes of somewhat questionable characteristics (every-bodies jets at this point ) was probably not in their best interest.

The record setting plane in 1945 and the record setting plane in 1946 (to get it back from the Americans) are referred to as F.4s but the 1945 plane is very likely a prototype.

 

[Koopernic]

It's easy to misread the contract numbers as aircraft model or mark numbers.

 

[Neil Stirling]

Hi Koopernic.

As far as I know it was intended to uprate the Derwent 1 as you say; however, possibly due to post was economies this was not proceeded with.

Aircraft Engines of the World 1946.

The Derwent V went into quantity production September 1945.

Rolls Royce Brochure.

The performance of the Derwent V varied between 3,500 lbs/st and 4,000 lbs/st

Aircraft Engines of the World 1946.

Rolls Royce brochure.

Meteor IV Performance here note G-41F Long span and G-41G short span. https://dl.dropboxusercontent.com/u/93074546/Meteor IV performance.zip

Neil.

 

[Neil Stirling]

Hi Shortround6

With 140 aircraft on hand (?) I have no idea why they didn't enter service until 1948.

With the War over and no money plus loads of surplus fighters, I would imagine there was no rush. I would expect that had the threat been sufficient the Meteor IV would have entered service during 1946.

Neil

 

[bada]

The Meteor F4 also slightly raised Mach limit and overcame the issue of heavy ailerons which had been deliberately incorporated into Meteor III to prevent the pilot overstressing the airframe. Obviously as the "Speed Meteor" exceeded 600mph at near sea level around November 1945 the Derwent V was at an advanced stage and could have been incorporated in production aircraft around the same time, perhaps slightly derated from their 3500lbs initially. There certainly would have been potential need: the fastest versions of the V1 missile reached 515mph at low altitude, during tests in Feb and March 1945.

hum, another 262 thread turning into a 262 vs meteor:

so what you wrote above is not really right , as this information comes nowhere to be find in the RAE report on the Meteor MKIII from april 1946!
The meteor was simply a badly engineerd plane and not suitable for(high speed) air-combat.
The report is to be find on mike william's page and is really worth to be fully read.
As the speeds you mentioned, they means nothing if the plane isn't capable of maneuvering and just flying straight.
Any combat maneuvre starts with ailerons, that's where the meteor lacks the most, the engine surge is also another very important point especially if there is very limited time to try to restart a shut-off engine,not even talking about the sneaking at high speed (=262's cruise speed).
If the Meteor met the schwalbe in combat, there is very few what a meteor could do...actually nothing as the 262 was the most easy to fly and faster of them both.
This 33 pages RAE report is really,really worth of reading!

 

[thedab]

look like the 262 had poor handling as well

 

[Koopernic]

Meteor F.4 only trickled into RAF service because a great many were exported e.g. 100 to Argentina.

While the Meteor III seems a flawed machine, I think it below the Me 262, in some respects its handling was quite good and of course one purpose of reports and critiques is to encourage improvement.

The Meteor F.4 had clipped wings, this overcame the airframe over stressing issue and allowed the ailerons to be rigged more lightly. As well it increased roll rate. The nacelles were extended yet again, thereby increasing the red line speed (and Mach limit) by a surprising 75mph.

In terms of it being a poor design, I suppose George Carter of Glosters did the best he can. The RAE, or whoever was in charge of aerodynamic development equal to the NACA or DLR in the UK, was not likely supplying very much knowledge of supersonic or transonic data. They knew enough that they should use thin wing sections and a fine body. The Power-Jets/Rover/Rolls Royce Wellands and Derwents had an extraordinary large diameter. For instance the Derwent I,II and V all had a dimater of nearly 42 inches (1.1m) compared to 32 the Jumo 004B's inches (0.8m) and the Derwent I/II was in the same thrust class.
What could be done, using open scientific papers from the likes of the Swiss-German Professor Jakob Ackeret is shown with the Miles M.52, a quite functional well thought through design with its biconvex wings.

This greatly restricted emgine/airframe integration. Underslung engines didn't work apparently forcing integration within the wing spars. I suspect Glosters might have done better with a single engine design such as the Gloster E.1/44 or simply extending the Gloster E28/39.

By contrast the Germans emphasised minimal diameter and frontal area from the beginning. The First German Jet engines such as the Heinkel-Hirth HeS 3 had not only a centrifugal compressor but a radial inflow turbine. A radial inflow turbine physically appears exactly as centrifugal compressor. von Ohain choosing this to ensure the compressor flow balances against the turbine as test chambers and rigs were not available. In order to keep frontal area low the Heinkel-Hirth engines added a first stage inductor fan and latter evolved with 1 or more axial stages after the centrifugal compressor. Hence while the Germans added some headache to engine development and reliability for themselves they also spared themselves a great deal. It seems to me that the Meteor F.4 and Me 262 were well matched when one assumes that the F.4's deployment would have been expedited and that the Me 262 would have had improved engines, though not as powerful as the Derwent. Of course timing is everything.

 

[GrauGeist]

look like the 262 had poor handling as well

Not all captured aircraft that were tested, were factory-fresh examples...

 

[GrauGeist]

PILOTS NOTES ON ME 262 BY FLUG KAPITAN WENDEL

In addition to studying the condensed instructions for airframe and engines, a thorough knowledge of these notes, preferably before the first flight in an Me262, is essential to the pilot.

1. Taxiing
Always accelerate the engines slowly. The gas temperature must never rise above the permitted value and the engine must not "roar" (bullern). In view of this, only take corners by using the brakes, never by using the engines. Always taxi gently and never make sharp turns, otherwise control of the aircraft will be lost.

2. Take-off
Switch on the fuel pumps in the main tanks. Hold the aircraft stationary by applying the brakes and then slowly run up the engines, especially slowly up to 7,500 r.p.m. The brakes must be so adjusted that they will hold the aircraft stationary up to 8,500 r.p.m.
After releasing the brakes, push the throttle lever right forward and then check over the engine. The aircraft makes so little demand upon the pilot at the commencement of the take-off run that he is easily able to carry out this check. The check is done by eye and ear, the engines must not "roar" and the instruments must show the same values as they did during running up or during previous take-offs. The gas pressure must be especially watched, and if it is more than five per cent lower than previously, do not take-off. In such a case, it is most likely that cavitation has taken place in one of the compressor stages, that is, by running up too quickly, the compressor has been overloaded and the smooth flow breaks up, exactly as it does when a wing stalls. Cavitation takes place so easily in many compressors as a result of small constructional faults or as a result of foreign bodies that they become entirely unserviceable. If the take-off is continued when cavitation has occurred in the compressor, then the quantity of air flowing through is too small, the quantity of fuel injected however is the same or sometimes even larger, as a result of which, the engine is overheated. The directional corrections during take-off should only be made with the brakes. The control column should remain in the neutral position.
The angle of attack of the wing, when running on all three wheels, is smaller than the angle of attack when flying at the lowest possible speed (after becoming airborne). As a result of this, when the aircraft has reached the lowest permissible flying speed, the angle of attack must be increased, in other words, the air craft must be pulled away from the ground. If the stick is pulled back too soon, or if, at the right speed, it is pulled back too far, then there is only a rise in resistance, but no increase in lift, in fact, there may be a lessening of lift. The aircraft cannot then climb. In this case immediately reduce the angle of attack to the "running" angle, in other words, push the stick forward and then start the process again.
When will the aircraft be pulled off the ground? It is best to go by the A.S.I, which should read with a fighter, fully laden i.e. 6,700 kg., 190 - 200 k.p.h. with a bomber, fully laden i.e. 7,100 kg., 200 - 220 k.p.h. After becoming airborne, immediately push the stick forward slightly as the required elevator angle for pulling off the ground is greater than that for climbing at the slowest speed. Essential for a perfect take-off is correct setting of the tailplane. The tailplane must always be trimmed nose heavy! The further back the centre of gravity moves, the more nose heavy it must be trimmed. When the 600 litre fuel tank is full, the center of gravity is at its rearmost position. The tailplane must then be set at +2 X - +3 i.e. 4-6 graduations on the indicator.

3.Rocket Take-Off - if so equipped
In order to shorten the take-off run, the rockets should be ignited 40 - 30 k.p.h. before the optimum take-off speed. If the take-off run need not be shorter, but there are obstacles to be negotiated after becoming airborne, then only ignite the rockets later, possibly even leaving it until the aircraft is airborne. Jettison the take-off rockets at low speeds, otherwise damage may be caused to the fuselage.

4. Operation of undercarriage and landing flaps
The undercarriage and landing flaps are hydraulically operated. The hydraulic pump has a capacity of 18 litres/min. and is attached to the port engine. Its capacity is rather too low and it is intended to fit an 18 litre per minute pump on the starboard engine. In the present state, therefore, the undercarriage operates very slowly. This is particularly noticeable when lowering. The nose wheel comes down very much later than the main undercarriage; so lower in plenty of time. The high speed of the aircraft easily tempts one to lower the undercarriage of flaps whilst travelling too fast and this leads to damage. The permissible operating speed must be rigidly adhered to.

5.Emergency operation
Compressed air is used for emergency operation of the undercarriage and it lowers the nose wheel and the main undercarriage fairing. The undercarriage itself falls under the influence of gravity. If it does not immediately lock, then assist it by side slipping.

6.Warning
The compressed air is only admitted to the undercarriage or flaps after two full turns of the operating handle have been made. With emergency operation both undercarriage and flaps lower more quickly.

7.Flight
Always climb at the optimum climbing speed, never more slowly. The best speeds are given in the table below.
0 m. altitude speed 475 kph
2,000 m. altitude speed 500 kph
4,000 m. altitude speed 525 kph
6,000 m. altitude speed 550 kph
8,000 m. altitude speed 600 kph
10,000 m. altitude speed 650 kph

Note: The Me 262 has an altitude compensated A.S.I, and, therefore, the indicated speed is equivalent to the true speed above 400 k.p.h.
The highest permissible rearward point for the centre of gravity is 30 percent of the mean aerodynamic wing chord. If this position is exceeded, then the aircraft becomes unstable about the lateral axis, that is, it does not remain trimmed, but will automatically stall in a turn. Under normal conditions of fuel stowage this position is not exceeded, but it is necessary always to watch most carefully the transfer pumping instructions. Watch particularly that the main tanks do not overflow as the J-2 fuel will run out into the fuselage and get on the wifeless equipment which interferes with radio traffic.
When cruising, the tailplane must be between 0 and +2.

8.Directional Stabililty
When the center of gravity is far back and the Flettner rudder trimming tabs are not perfect, especially if the Flettner tabs are a little too thick, then the aircraft sways about the vertical axis. This movement must stop when both legs are pushed hard against the rudder pedals. If this does not stop the movement then the tabs must be altered or the trailing edge of the rudder must be bent slightly outwards. A modification is in course of preparation.

9.Landing
The best approach speed is 230 - 250 k.p.h. Shortly before reaching the airfield boundary, decrease the glide angle a little and reduce the speed to about 200 k.p.h. Then flatten out and touch down normally as with an aircraft having a tail wheel. Touch-down speed is 175 k.p.h. After touch-down, allow the aircraft to tip forward slowly. Only apply brakes when the nose wheel has touched the ground.

10. Going round again
It is just as easy to go round again as with other types of aircraft, but is must be remembered that by approaching slowly the engine revolutions are low, and just as at take-off, the throttle lever must only be moved forward slowly.

11. Single Engine Flight
When flying on one engine only, a turning moment is developed about the vertical axis, due to the engine being offset from the longitudinal axis of the aircraft. The amount of this moment is dependent upon the power and the leverage. In this case the leverage remains constant, but the power (i.e. the effect of the running engine) changes. In order that the aircraft may remain on course, this moment must be offset, which is done by applying rudder. The amount of rudder applied must be sufficient to keep the ball of the turn and bank indicator in the center; note this particularly in turns.
Turns can be made either with or against the stationary engine. During long single-engine flights the force on the rudder pedal may be reduce d by adjusting the Flettner trimming tabs.
The turning moment imparted by the specific movement of the rudder is dependent on air-flow pressure.
The smaller the pressure, the greater must be the rudder movement. In single-engine flight, with retracted undercarriage, the speed is something over 500 k.p.h. at full throttle. In this case only about y$ of the possible rudder movement is necessary. This low speed, however, can only occur at full throttle if one is climbing at too great an angle or if the undercarriage has been lowered.

12. Single Engine landings
From what has previously been said, it will be seen that the following is necessary for a single-engine landing; minimum approach speed 260 k.p.h., so that, if necessary, full throttle may be given. At this speed and with one engine at full throttle, the aircraft loses height with lowered undercarriage, but raised flaps at 1 - 2 ms/sec. From this, it will be seen that the undercarriage should only be lowered at such a time that it is possible to reach the airfield with little or no aid from the engine. Approach speed 260 k.p.h. About 500 ms. before reaching the airfield (when too high earlier, when too low later) lower the flaps and complete the landing in a normal manner. Side slipping is possible.
When landing, the Flettner trimming tabs should be set in the neutral position. If it is necessary to approach under power, then the necessary force on the rudder must be exerted by the pilot. At full throttle under all circumstances apply full rudder.

 

[Koopernic]

View attachment 273525

look like the 262 had poor handling as well

Here some observations from Eric Brown:

Regarding the brakes he wrote on page 245 :"After lining up the aircraft on the runway, the engines were opened up to 8500 rpm on the brakes, and a check was made that the Zwiebel (onion), as the exhaust cone had been dubbed, was protruding from each orifice.

Full power of 8700 rpm was then applied and a quick check was made on the jet pipe temperature, burner pressure, and fuel pressure."

Regarding handling characteristics he wrote on page 252:" The normal range of flight characteristics from aerobatic manoeuvres to the stall revealed the Me 262 as a very responsive and docile aeroplane, leaving one with a confident impression of a first class combat aircraft for both fighter and ground attack roles. Harmony of controls was pleasant, with a stick force per 'g' of 2.72 kg (6lb) at mid-CG position and a roll rate of 360 degrees in 3.8 seconds at 645 km/h (400 mph) at 1525m (5000 ft)."

Regarding the 'snaking' he wrote that the German engineers managed it better to tame it, during the war, than i.e. Gloster engineers with the Meteor I, which had the same problems.

So we have, for the Me 262 a roll rate of 360 degrees/3.8 seconds or 95 degrees second at 400mph. This is quite fast, Faster than the very fast rolling P-51B/D which at that 400mph speed rolled at 85 degrees/second and faster than the 80 degrees second of the long wing Meteor F.4 (I am assuming the normal British/US practice of 60lbs stick force, I do not have short wing meteor F.4 roll rate). The Me 262 had spring servo tabs to reduce pilot workload and a telescoping joy stick to allow more leverage of the joy stick. I've seen turn rate charts which show that Me 262 turned faster (in degrees/second) than the P-51 though the P-51 could still turn inside the Me 262.

The poor handing refers to snaking at 350mph IAS. At 25000ft 350 mph IAS = 305 knots IAS which becomes 457 knots TAS or 525 mph TAS!. Hardly an impediment considering the P-80, Meteor III barely reached this speed. I have variously heard that the onset of snaking was 460mph, 480 mph or that it could be cured by methodical trim tab adjustments. The problem is complicated but relates to airframe tolerances, uneven shockwave formation, the distribution of mass in a jet, the lack of gyroscopic action by the propeller.

Some Me 262 were produced in forest factories, without full jigs and had poor tolerances.

Snaking was a significant problem of the Meteor, P-80 and Me 262 as indeed it is in most jets. I believe the only way to deal with it is a yaw damper: a rate gyroscope with differentiation circuitry to kick opposite rudder. The Germans had developed this technology and tested it on an Me 262. (see my preceding posts on the yaw dampers of Dr. Karl Doetsch )

Most late war German aircraft had poor brakes, I would say it reflects on shortages and cost savings rather than a flawed design. Trim changes when extending the undercarriages are perhaps unpleasant but hardly effect the aircrafts fighting ability.

Me 262 tested in the USA had the problem that their engine log books had been lost, meaning the engines may have been near end of MTBO interval.


The Meteor F4 was clearly superior to the Me 262 however the contemporary of the Me 262 in April 1945 was the Meteor III, which was inferior to the F4 and Me 262. April 1945 marks the attempted date for engine improvements on the Me 262.

 

[davparlr]

Even while the Me262 was being developed, Willy Messerschmitt had the next generation on the drawing board: the HG series.

The delay in the HG series was the engines, which he had planned on being advanced sooner than what actually occurred. This was also the short-comings of the He280 program. Simply put, the agonizingly slow development of the engines stalled the aircraft advancement.

Me262 V9 (Wknmr 130004) was the first in the series of the HG program, though V9 had little changes, it did test several concepts like a low profile canopy, some slight design changes and "clean" surfaces.

HG II was designed to have a low profile canopy, 35° swept wings and a "V" tail. HG III was to have 45° swept wings, embedded engines in the wing-root and a more conventional tail assembly (although a "V" tail was also included in the designs).

Up engining the Me 262 would certainly kept it in competition with the upgrading P-80, P-84, Vampire, and Meteor. I do not think the swept wing versions would have competed successfully with the slightly later P/F-86 and Mig 15 types. I do think it could be an excellent bomber interceptor ala heavier Yak 25.

Single engine He-162C would have been as good or better day fighter at lower cost. If Me-262 remains in production during fall 1945 it would be as twin seat night fighter and perhaps as a recon aircraft.

The He-162 had potential but it was a very small aircraft. Looking at the one at the Chino museum I could look directly into the engine which means the complete fuselage was below my head. I would always be like a Bf-109, a limited point defense fighter. It only held 1100 lbs of fuel. Not much for a jet and not much room. Bigger engines would drink more fuel.

Germany was on the verge of second generation jet types, and one of those was the Me P.1101, which did have a single engine and a very modern design. The P.1101 was set for production and probably would have seen combat had the war drug on longer. Now, by saying it would have seen combat, keep in mind that Germany had next to no resources for large-scale production OR even enough fuel to get these in the air in any significant numbers to do any good.

The second generation jet engines were already quite behind the allied jets. The Goblin was already rated at 2700 lbs thrust Jan, 1945, the Nene had run at 4000 lb thrust in Oct. '44, and reached 5000 lbs thrust on its second run. The Americans had run the centripetal flow J33 at 4000 lb thrust in Feb, '44, and the axial flow J35 at 3620 lbs thrust in April, '44, so they were in excellent position to stay up with German advancements in advanced jet integration.

I do think you are right about the P.1101. I think it could have been the first swept wing aircraft and since it had ground adjustable sweep, it could determine the best angle for a fixed sweep aircraft. I also think it could have been clearly superior over the contemporary jet aircraft, for a few months.

 

[awack]

That report on the me 262 is the one in which the me 262 had its tabs disconnected, the 262 most like characteristic by pilots was its handling, especially at medium and high speeds, not so good at low speeds.

 

[GrauGeist]

The He-162 had potential but it was a very small aircraft. Looking at the one at the Chino museum I could look directly into the engine which means the complete fuselage was below my head. I would always be like a Bf-109, a limited point defense fighter. It only held 1100 lbs of fuel. Not much for a jet and not much room. Bigger engines would drink more fuel.

However, the He162 was much lighter than any other jet, and because of this, it was faster.

The second generation jet engines were already quite behind the allied jets. The Goblin was already rated at 2700 lbs thrust Jan, 1945, the Nene had run at 4000 lb thrust in Oct. '44, and reached 5000 lbs thrust on its second run. The Americans had run the centripetal flow J33 at 4000 lb thrust in Feb, '44, and the axial flow J35 at 3620 lbs thrust in April, '44, so they were in excellent position to stay up with German advancements in advanced jet integration.

I do think you are right about the P.1101. I think it could have been the first swept wing aircraft and since it had ground adjustable sweep, it could determine the best angle for a fixed sweep aircraft. I also think it could have been clearly superior over the contemporary jet aircraft, for a few months.

A few things to look at, in regards to the engines, were the weight of the airframe they were installed in. The He280 was a fast and nimbly aircraft and performed well with the lighter HeS8 even though the HeS30 was the preferred choice. When it became aparent that the HeS30 wasn't available, they tried installing the Jumo004 and discovered that the 004 was simply too heavy and hurt the He280's performance.

In many of the arguments I've seen, regarding jet engine performance, the argument always seems to lean toward "engine X is putting out this much thrust versus engine Y that produced this much thrust" however, the weight and size penalty of "engine X over engine Y' needs to be taken into consideration.

I'll give an example:
The He280 weighed 9,416 lbs. (4,280kg) and each HeS8 weighed 837 lbs. (380kg)
Each HeS8 produced 1,320 lbf. (5.9 kN) of thrust.

The Me262 weighed 14,272 lbs. (6,473kg) and each Jumo004 weighed 1,585 lbs. (719kg)
Each Jumo004 produced 1,980 lbf. (8.8kN) of thrust.

So in an attempt to "upengine" the He280, they installed a larger, heavier engine (nearly twice the weight) that only gave an increase of roughly 600 lbf. (2.6kN).

 

[stona]

I always remember Eric Brown's comment on being sent by the RAE to Germany to assess the latest Luftwaffe types, including the Me 262 (which he described as the 'most formidable' fighter of WW2)

"I was more than surprised, I was shocked because they were so far ahead."

That, from the Chief Naval Test Pilot at the Royal Aircraft Establishment, who would have been au fait with all the latest British developments, is a surprising and illuminating statement.

Cheers

Steve

 

[Juha]

I..That, from the Chief Naval Test Pilot at the Royal Aircraft Establishment, who would have been au fait with all the latest British developments, is a surprising and illuminating statement.

Cheers

Steve

Still, while he had flown Meteor Mk I in early 44, he flew Meteor Mk III first time only in 1946. But true, he thought that even Mk IV didn't reach the level of Me 262.

Juha

 

[OldSkeptic]

Oh the 262 was a damn good airframe, better than anything the allies had until the F-86/Mig-15 era and capable of a lot of further development.

Obviously the first was reliable and easier to use engines. But the airframe had the potential to have a lot of different weapon systems added. Not to mention a two seater, radar equipped nightfigher version too.

But we are back to engines again. The German 'big mistake', going for 'perfection' with an axial flow engine, rather than developing the theoretically inferior but simpler to make centrifugal ones (which you could bootstrap from supercharger manufacturing). Lucky for us, can you imagine the havoc caused by numbers of 262s in late '43....oops.