Mistakes in Aviation

[kool kitty89]

Where did i say the Meteor Mk.I was even close to the Me 262?

Well the Mk. I certainly had problems, but it did have one advantage over prop fighters, the top speed of ~410-420 mph was achieved at low level and thus gave it a good advantage there. (it would have been very successful against the V-1's if not for the jamming guns caused by flawed case ejection chutes) Granted the Me 262 in any operational for was greatly superior to the Mk I.

But remember the improvements in the Meteor III, the long chord nacelles (introduced after initial production, but also retrofitted) greatly improved compressibility problems and added ~75 mph to top speed even with the Welland (1,700 lbf) engines giving a top speed of ~495 mph, increased to ~520 mph with Derwent Mk. I engines. (and there were also Derwent II -2,200 lbf, and IV -2,450 lbf- but I don't know if they were used operationally)

Granted the Meteor III had the ailerons wired heavy to limit wing stresses and allow it to be cleared for aerobatics, resulting in a rather poor roll-rate.

The Meteor III was coming closer to the Me 262's performance, but still at a significant disadvantage in performance (except in a turn). And even in the F-4 meteor, the compressibility problems were significant, with bad snaking around .8 Mach and buffeting, exceeding the limiting Mach number (limited by the tail on these models) could result in violent shock-stalls sometimes with irrecoverable loss of control or structural failures. These were eventually addressed with a new tail on the F-8, allowing full control up to critical Mach with better characteristics when hitting crit Mach and a limit of ~.82 Mach.

The improvements to the Meteor came rater late in the war, but had there not been the problems from the horrible Rover arrangement the Meteor's development could have been nearly 2 years further along, and engine developments more so.

With either W.2/700 or Derwent IV engines (2,450 lbf) an improved Meteor should have been available much sooner, with improved airframe allowing full combat ability.(clipped and strengthened wings)

Not quite as the F-4 (with 2x 3,500 lbf engines) and still with Mach limitations of the tail, but probably somewhat lighter as well.

 

[i-kil-you]

i'd say the corsair because it was built for ww2, but was made just afterwards so it didn't get in.

 

[Haztoys]

i'd say the corsair because it was built for ww2, but was made just afterwards so it didn't get in.

...???...I "think' the Corsair was in WW11.. ..Or I'm reading this wrong....???

 

[kool kitty89]

??? You mean the F4U-5? Otherwise that makes no sense.

And the F2G "Super Corsair" turned out to be a failure.

 

[Haztoys]

I know one of the heels of the Me-262 was you could not spool up or down the engines very fast ...I can see were this would be a real problem in combat ... Could the Meteor engines be spooled up and down fast...

Or were all jet engines of the time that way...???

 

[buzzard]

Despite the avatar, I'll give him the benefit of the doubt. Maybe he meant the Bearcat.

As I understand it, ALL the early jet engines were very sensitive to throttle changes.

 

[Haztoys]

And the F2G "Super Corsair" turned out to be a failure.

KK....What makes you say it was a "said failure"...????...I was thinking do to the time it was made...It was just not needed and never put into production...Not saying your wrong ...I know dick ...Just wondering...

 

[kool kitty89]

Yes and no, in the case of the 262's Jumos, once you got above ~7,000 rpm rapid throttle movements weren't much of a problem. However basicly all early turbojets had rather slow throttle response and could suffer, flameout, compressor stall, or total failure. (sometimes with combustor rupture and engine fire) This is included on the Welland, Derwent I-IV, Goblin, J31, and J33 post war these were improved somewhat.

The Jumos and BMW 003's had fuel limiting devices to prevent dumping too much fuel at once, the problem was that at low speeds the 004B's wasn't yet functioning adequately, this was greatly improved on the 004D/E.

One additional problem with the German engines was since the turbines had to be air cooled, spooling up too rapidly had an additional problem: too much fuel entered the combustion chamber before the compressor had spooled up enough to supply the necessary cooling air and the combustors and turbine could overheat, and the turbine could be softened and warped.

 

[kool kitty89]

The Super Corsair's performance was no better than the F4U-5, and there were considerable control/stability problems iirc.


Back to the Jets:
Early jet engines

One problem with early engines was the control of injection of fuel and
temperature. In the Junkers Jumo 004B-4 the fuel flow was partialy
determined by a Barmag gear pump whose flow depended upon both engine
RPM. There was also a centrifugal governor that was set by the
throttle and that operated a fuel bypass valve so as to modulate the
fuel flow. Should the throttle be operated too rapidly too much fuel
could be injected before engine spool up and thus leading to the engine
shedding turbine blades or combustion chamber burnouts.

The early british engines suffered from this as well though not as
badly though it can be argued that the Welland at least lacked any
performance.

The Rival BMW 003 engine had a aneroid capsule across the compressor to
provide 'throttle limiting' thus spilling excess fuel untill it had
spooled up and was much easier to handle, something that was important
for the He 162 "Volksjaeger"/"Spatz" (Peoples
Fighter/Sparrow). Throttle limiting was under development inclusive
of a temperature probe to bypass excess fuel for the Junkers engine as
well.

There's a lot of interesting info on that thread.

and: Anselm Franz and the Jumo 004

 

[FLYBOYJ]

Yes and no, in the case of the 262's Jumos, once you got above ~7,000 rpm rapid throttle movements weren't much of a problem. However basicly all early turbojets had rather slow throttle response and could suffer, flameout, compressor stall, or total failure. (sometimes with combustor rupture and engine fire) This is included on the Welland, Derwent I-IV, Goblin, J31, and J33 post war these were improved somewhat.

The Jumos and BMW 003's had fuel limiting devices to prevent dumping too much fuel at once, the problem was that at low speeds the 004B's wasn't yet functioning adequately, this was greatly improved on the 004D/E.

One additional problem with the German engines was since the turbines had to be air cooled, spooling up too rapidly had an additional problem: too much fuel entered the combustion chamber before the compressor had spooled up enough to supply the necessary cooling air and the combustors and turbine could overheat, and the turbine could be softened and warped.

Combustors? Combustion cans or chambers perhaps?

One of the problems attributing to this were the design and construction of early fuel control units which had a series of bellows and diaphragms metering the fuel to the combustion chamber. Although brilliant in their design, some of the materials used in their construction were inferior, especially rubber seals and diaphragms. These components couldn't take rapid throttle movement and would sometimes split and tear within a few hours of operations. Additionally they also did not allow an accurate metered fuel flow to the combustion chamber, again contributing to flame outs. Early fuel controls were basically mechanical computers with kerosene running through them.

Another sore spot was during the start process where careful attention had to be given to ensure the turbine inlet temperature didn't exceed it's design limits. This was sometimes difficult during start as the only control of this in early jets were the already described inferior fuel control units. As far as i know in some early jets there was a "fuel c0ck" which metered fuel during the start process and was adjusted accordingly during the start process. One had to ensure there was enough fuel getting to the combustion chamber to ensure a "light" (and avoid a hung start) but at the same time control fuel flow enough so you didn't get an over temp.

 

[kool kitty89]

Combustor - Wikipedia, the free encyclopedia

Combustor - Burner

 

[FLYBOYJ]

Combustor - Wikipedia, the free encyclopedia

Combustor - Burner

Ask most A&Ps what a combustor is and they'll tell you it's part of their gas barbecue.

 

[kool kitty89]

And I guess "burner" would be even worse in that context.
(personally I've never heard a gas barbecue or stove burner referred to as a combustor though)

And that second link is a NASA page.

I guess the "combustor" term is used fairly extensively on the technical/developmental/experimental area of turbine engines. Results: combustor

(it also seems the term is used only for gas turbine engines' combustion chambers; interestingly the wikipedia Combustion chamber - Wikipedia, the free encyclopedia page doesn't even mention gas turbines)

 

[FLYBOYJ]

And I guess "burner" would be even worse in that context.
(personally I've never heard a gas barbecue or stove burner referred to as a combustor though)

The same way most people who actually worked on jet engines won't refer to the combustion chamber, cans, etc., as a combustor.

And that second link is a NASA page.

I guess the "combustor" term is used fairly extensively on the technical/developmental/experimental area of turbine engines. Results: combustor

(it also seems the term is used only for gas turbine engines' combustion chambers; interestingly the wikipedia Combustion chamber - Wikipedia, the free encyclopedia page doesn't even mention gas turbines)

Only a term an engineer or Wikipedia would endure - for the most part it's a combustion chamber, combustion can(s) or burner can(s) to those who have to maintain and repair these things...

 

[Kruska]

Where did i say the Meteor Mk.I was even close to the Me 262?

The improvements to the Meteor came rater late in the war, but had there not been the problems from the horrible Rover arrangement the Meteor's development could have been nearly 2 years further along, and engine developments more so.

Hello kk89,

Off course you never said that, neither did I

You wrote the Meteor was a good a/c, and I just forwarded that IMO the Meteor of 44, 45 wasn't a good a/c, but started to develop into such in the 50th.

The reasons that delayed the Meteor are just as valid as those regarding the 262, but nevertheless IMO the 262 was far better in 44,45 then its opposite the Meteor. Imagine the German industry would not have been so extremely limited on precious resources-metals and would have possessed a more or less intact industry such as England, the technological gap between both a/c would have been even greater in 44/45 in favor for the 262 despite its almost 2 year delay.

If Germany would not have been so lacking on the above mentioned issues, probably in 1945 the adversary of the Meteor would not have just been a 262 but also a Me P1101.

Regards
Kruska

 

[FLYBOYJ]

BTW a "simple" fuel control from a helicopter turbine engine.

 

[kool kitty89]

On the materials for German engines issue I pretty much agree, but even without them the engines were producing much more than the initial design thrust (004D with 930 kp normal and up to 1050 kp thrust overrev w/out AB at 10,000 rpm and TBO of over 60 hr, and 1000 kp normal for the 004E 1,200 kp AB) with improvements. (and the 003E's annular combustion chamber had a life of over 300 hr in testing, made largely of mild steel!)

The transition to nonstrategic materials didn't so much limit performance, it just delayed development of the engines.

I do think that things would have gone better if development of the 001 (HeS-8 ) 006 (HeS-30), 004, and 003 had been focused on and any larger (and more problematic) designs left on the drawing board.

In particular the HeS-30 (006) would have been excellent on the 262, power levels equal or greater than the 004m at half the weight and at ~24 in diameter roughly 1/2 the frontal area. (in addition to being much shorter) And with much lower fuel consumption. (using a reaction type 5-stage axial compressor, achieving similar performance to the jumo's 8-stage impulse bladed compressor at a high efficiency) And much better operating characteristics and engine life.

Range, speed, climb, roll rate, turning ability, and spool-up performance all increased dramatically. (and weight reduced to ~12,500 lbs with full internal load, compared to 14,100 lbs)


And as to the need of more powerful engines for the larger single engined fighters like the P.1101 (or improving the He 162) even without the class II engine designs (HeS 011A rated for 1,300 kp, while weighting roughly 900 kg) developments of the 004 and 003 were sufficient (not to mention possibilities for the 006) with the 004E producing 1,200 kp with afterburner (possibly more with overrev to 10,000 rpm) weighing roughly 700 kg and the smaller 003D (redesigned reaction type compressor) producing 1,200 kp dry weighing only ~550 kg.

 

[red admiral]

You wrote the Meteor was a good a/c, and I just forwarded that IMO the Meteor of 44, 45 wasn't a good a/c, but started to develop into such in the 50th.

The Meteor I, II and III were all prototypes rather than actual fighters with the Meteor IIIs being rushed into service to shoot down V-1s because they were fast at low level. The Meteor IV from the middle of 1945 was the first real fighter version with a considerable excess in performance over the Me 262. The Mach limit with the longer nacelles was increased to M0.81 before control problems started to occur. Speed and rate of climb massively jump up to better the Me 262's figures.

Most of the new jet aeroplanes in the pipeline for the Luftwaffe were only likely to "work" in 1946-47 and even then, there are considerable flaws with the designs most likely to be produced. Take the Ta 183 for example, which was produced in Argentina post war by FMA as the Pulqui with a massively more powerful and reliable engine. It was still a dog to fly. Most of the Luft 46 designs pin their hopes on the HeS 011 which never came close to making it's designed thrust in postwar development.

 

[Kruska]

Hello red admiral,

I don't quite agree to your posting.

The first F 4 prototype flew on 17 May 1945, and went into production in 1947. So it wouldn't be a fitting match for the 1944/45 Me262.

Also the comparison to a Pulqui doesn't fit since Argentina had no previous a/c industry to back such a project. However the FW team in majority was taken into Russian "hospitality", so that the MiG15 for sure incorporated a major share of these engineers knowhow.
The wing design is an absolute match to the previous FW design plans. From what I read the Meteor F4 and the later Korean versions FR9 or NF11 was no match for a MiG15.

In most publications referring to the Meteor, it shows that despite a vast range of mission roles and models, the Meteors mostly were used in the Ground Attack role, due to non satisfying performance as a fighter.

But my main point of view would be the fact that the Me262 could never proof or show its true potential due to non existing – extremely limited – metals/alloys and a totally out powered industry. Other forum members are far more knowledgeable then me in regards to the engine/turbine design of the German jets, but for what I conclude the problem was the usage of inferior materials – not the jet design itself.

Regards
Kruska

 

[red admiral]

The first F 4 prototype flew on 17 May 1945, and went into production in 1947. So it wouldn't be a fitting match for the 1944/45 Me262.

There was no rush to produce the F.4 postwar, in any scenario where war rolls on then they start on the production line in late 45 but probably without the clipped wings.

The design team on the Pulqui II was lead by Kurt Tank and most of the FW design team in Argentina. The MiG-15 had absolutely minimal input from German designs, this myth being debunked back in the 80s. The argument of "it looks the same" i.e. it is single engined and has a swept wing is fairly ridiculous compared to the hard data showing its evolution from earlier Soviet projects such as the MiG-9.

The Meteor was used mostly for ground attack as by Korea it was outmatched by the 2nd generation of jet fighters. It became a two-seat night fighter instead given the lack new design for this requirement (eventually Sea Vixen and Javelin)

The problem with the German jets was the design itself (especially the 004) rather than any materials problems. The materials limit turbine entry temperature, which the Germans got around mostly from air cooled blades. The TETs of the Allied jets were only about 50K higher at most giving very slight advantages in specific thrust and fuel consumption (around 5%). With the Jumo 004, the German designers managed to design a jet that offered similar thrust to the Whittle designs, fuel consumption about 50% worse, chronic unreliability from surge problems with the axial compressor, and that weighed twice as much. Most of the problems came from the axial compressor, which weighed loads, had a very low pressure ratio, poor reliability (mostly surge from quick throttle movements) and had poorer efficiency than the supposedly inferior centrifugal compressors.