The forgotten holocaust

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#61

Ah, now we’re getting somewhere - it was a hybrid jet-rocket interceptor, meaning it will have a lower ceiling than the normal jet powered version and will be a bitch to control when above this altitude with the rocket off.
Given that this is an adaptation of what was already a fairly short legged aircraft, I think the following assumptions are reasonable:

  1. The total range on jets would be very poor due to the additional weight, space and drag penalties of the rocket motor.
  2. Burn time on the rocket motor would be very poor - 5 minutes maximum?
  3. The radius about the point rocket motor burn started from which it can make an intercept at 45-50,000ft will not be very high. Indeed, it may be possible for an aircraft of relatively slow performance to get completely out of this circle if it is quick on the uptake as the aircraft will take a minute or two to climb to intercept altitude.

Errr… not exactly. An awful lot depends on the exact aerodynamics, wing loading, etc. but it is entirely possible for an aircraft in that condition to have only 5 km/hr difference between stall speed and Vne (Velocity Never Exceed - i.e. the speed at which bits start falling off). While it is possible to control an aircraft in these conditions, fighting it is something entirely different - turns will be very restricted indeed as any sharp turns will put you in a spin, and as soon as the rocket motor fuel runs out you will stall pretty much immediately.

I’d have to say that such a service ceiling is HIGHLY improbable. That aircraft relied on an engine nobody ever got working properly (the HeS 011), swept wings which in practice turned out to require a huge amount of effort to make flyable (wing fences, turbulators, kuchemann tips, custom-twisting of wings, etc. - none of which the Germans had a clue about) and at 12kN thrust had just over a third of the power of the MiG-17 which incidentally had a much lower service ceiling and substantially bigger wings. The only way the pilot of an P.1106 would reach 20km altitude would be if his aircraft blew up inder him!

There’s a rather interesting USAF video of it on YouTube here, which gives a service ceiling of ~35,000 ft (limited by a lack of cockpit pressurisation). Controllability at high altitudes (by implication around 35,000 ft) is also assessed as poor.

#62

Almost - the Germans did indeed produce the first SAMs in the world (Wasserfall), but they weren’t very good and the guidance systems were flaming awful. Essentially it consisted of a guy with a joystick steering the rocket so it went in a straight line between his eyes and the target. This, of course, is both a very inefficient intercept solution, easy to jam/confuse and totally dependent on clear weather. There was a very similar system that essentially provided a radar picture the operator could use instead of his eyes, but that was little better. Finally, a semi-automated system was being developed which could have made life a bit easier for the operator (they would have had to track the aircraft with a radar, rather than do this as well as steering the rocket with a joystick) but this was never fielded and would have been childishly easy to jam in any case.
Incidentally, by 1944 the US had produced fully automated radar guided anti-aircraft guns using a far better guidance system which was adapted postwar for all early SAMs. The Germans never had anything similar.

Err… I think you mean B-17/B-24. The B-29s were only ever used against Japan and were capable of flying far higher and far faster, with intercepts being consequently much harder.

Uh huh. So that’s why Adolf Galland (arguably one of the very best pilots of the war) was shot down by a P-47 while attacking a bomber formation? They were certainly easier to shoot down on takeoff/landing due to their very poor acceleration (which is why the allies attacked them then - they weren’t fools) but they were by no means invulnerable at other times.

Did you even read the table I posted? Service ceiling at maximum take-off weight is 10,000 metres, and typical over-target altitude (i.e. having burned off half the fuel) is 14,000 metres. Absolute ceiling (i.e. dry and zero climb rate) is around 16,000 metres.

They can build as many as they like, the only way they’re going to reach 14,000 metres is if they stack them one on top of the other!

Correct. However, that isn’t a major issue as there weren’t any other fighters which could reach them either!

Sure they can - but why would they? Remember that the Germans thought nuclear weapons to be a theoretical impossibility, and so have no reason to understand the absolutely critical need for a watertight air defence. If the USAAF were to hold the B-36s back as nuclear bombers (and this is probable if that is how they plan to end the war) then the first the Germans will know that such a high altitude aircraft exists is when it flies over them and burns their country to cinders. Hence, unless the Germans had implausibly good intelligence about the B-36 and the Manhattan Project (and remember that in WW2 the Allied intelligence services ran rings around them) they won’t build up the airfields, radar stations and high altitude fighters needed to defend against it.

#63

More than that - just about all the spare wiring, gun turrets, bunks, kitchen, crew members, paint, etc. were stripped out to reduce weight. These really were ultra-lightweight aircraft which explains why they reached such high altitudes.

Marginally, but it was very vulnerable indeed to the MiG-17 and was accordingly retired almost immediately after the MiG-17 came into service.

Yep. It might have got away with it for a bit - it had very long range, and the Soviet radar systems were initially very poor in places so if it got in without detection it would be unlikely to be intercepted - but certainly by the early 1950s it was obselete.

#64

Indeed, excellent scientific dialogue, honorable ladies and gentlemen! So let’s continue the exploration! :slight_smile:

It was a hybrid jet-rocket interceptor, meaning it will have a lower ceiling than the normal jet powered version and will be a bitch to control when above this altitude with the rocket off.

Excuse me, my dear Mr. Pdf 27, but that is a direct example of the so-called linear extrapolation. Planned ceiling (yes, completely anticipated value!) for the Me 262 C-3a Heimatschützer III was 14.300 meters, and that numerical value is clearly superior than 11.560 meters, presented as a maximum service ceiling for the Me 262 A-1a variant. The key role factor for this obvious discrepancy is the thrust/weight ratio, which is greatly improved in this case we have here.

The total range on jets would be very poor due to the additional weight, space and drag penalties of the rocket motor.

Not necesssarily, my dear Mr. Pdf 27. Implementation of the additional drop tanks, as well as of a new completely new, innovative towed winged fuel tank system called Deichselschlepp (actually tested with the prototype Me 262 V 10 – VI+AE, W.Nr. 130005) would be a completely acceptable solution for this problem.

Burn time on the rocket motor would be very poor - 5 minutes maximum?

Yet again theoretically - fifteen minutes (+/- 3 minutes), to be more exact.

The radius about the point rocket motor burn started from which it can make an intercept at 45-50,000ft will not be very high.

Theoretically correct conclusion, my dear Mr. Pdf 27, but the real question in this issue is the factual capacity of the internal, fuselage tanks. For example, by inserting a new 1,15 meters long section in the centerplane, additional 1635 liters of rocket would have been completely available.

turns will be very restricted indeed as any sharp turns will put you in a spin, and as soon as the rocket motor fuel runs out you will stall pretty much immediately.

Theoretically, blown flaps are still available as an aerodynamically completely acceptable solution in this case, my dear Mr. Pdf 27. Furthermore – Ho 229 A1 is a pure jet airplane, therefore termination of the thrust provided by the rocket engine is not a problem in this case. :slight_smile:

That aircraft relied on an engine nobody ever got working properly (the HeS 011)

Excuse me, my dear Mr. Pdf 27, but I have a minor impression that we are not talking about the same aeroplane. The Messerschmitt P. 1106 R was a pure rocket-fighter, which had Walter HWK 109-509 S2 rocket engine with a static thrust of 19,3 kN, mounted in the frontal part of the fuselage (thus equipped with a low-drag solid nose). That engine represented an improved variant of the rocket motor envisioned for the legendary DFS 228 high-altitude reconnaissance aircraft designed by the Deutsche Forschungsanstalt für Segelflug, which had the envisioned service ceiling of 25,000 m. And I am assuring you that Dr. Felix Kracht was a very well educated and completely sane aeronautical engineer, and not an insane crackpot-scientist.

which gives a service ceiling of ~35,000 ft (limited by a lack of cockpit pressurisation). Controllability at high altitudes (by implication around 35,000 ft) is also assessed as poor.

Soviet results, confirmed by Yugoslav comparative examinations (oh, yes – we have tested that cute little thing too!) are indicating 14.758 meters as a completely accessible value. On the other hand, absence of the pressurized cockpit has certain advantages – absolute nonappearance of the explosive decompression, potentially highly probable in air combat.

#65

Indeed, excellent scientific dialogue, honorable ladies and gentlemen! So let’s continue the exploration! :slight_smile:

It was a hybrid jet-rocket interceptor, meaning it will have a lower ceiling than the normal jet powered version and will be a bitch to control when above this altitude with the rocket off.

Excuse me, my dear Mr. Pdf 27, but that is a direct example of the so-called linear extrapolation. Planned ceiling (yes, completely anticipated value!) for the Me 262 C-3a Heimatschützer III was 14.300 meters, and that numerical value is clearly superior than 11.560 meters, presented as a maximum service ceiling for the Me 262 A-1a variant. The key role factor for this obvious discrepancy is the thrust/weight ratio, which is greatly improved in this case we have here.

The total range on jets would be very poor due to the additional weight, space and drag penalties of the rocket motor.

Not necesssarily, my dear Mr. Pdf 27. Implementation of the additional drop tanks, as well as of a completely new, innovative towed winged fuel tank system called Deichselschlepp (actually tested with the prototype Me 262 V 10 – VI+AE, W.Nr. 130005) would be a completely acceptable solution for this problem.

Burn time on the rocket motor would be very poor - 5 minutes maximum?

Yet again theoretically - fifteen minutes (+/- 3 minutes), to be more exact.

The radius about the point rocket motor burn started from which it can make an intercept at 45-50,000ft will not be very high.

Theoretically correct conclusion, my dear Mr. Pdf 27, but the real question in this issue is the factual capacity of the internal, fuselage tanks. For example, by inserting a new 1,15 meters long section in the centerplane, additional 1635 liters of rocket would have been completely available.

turns will be very restricted indeed as any sharp turns will put you in a spin, and as soon as the rocket motor fuel runs out you will stall pretty much immediately.

Theoretically, blown flaps are still available as an aerodynamically completely acceptable solution in this case, my dear Mr. Pdf 27. Furthermore – Ho 229 A1 is a pure jet airplane, therefore termination of the thrust provided by the rocket engine is not a problem in this case. :slight_smile:

That aircraft relied on an engine nobody ever got working properly (the HeS 011)

Excuse me, my dear Mr. Pdf 27, but I have a minor impression that we are not talking about the same aeroplane. The Messerschmitt P. 1106 R was a pure rocket-fighter, which had Walter HWK 109-509 S2 rocket engine with a static thrust of 19,3 kN, mounted in the frontal part of the fuselage (thus equipped with a low-drag solid nose). That engine represented an improved variant of the rocket motor envisioned for the legendary DFS 228 high-altitude reconnaissance aircraft designed by the Deutsche Forschungsanstalt für Segelflug, which had the envisioned service ceiling of 25,000 m. And I am assuring you that Dr. Felix Kracht was a very well educated and completely sane aeronautical engineer, and not an insane crackpot-scientist.

which gives a service ceiling of ~35,000 ft (limited by a lack of cockpit pressurisation). Controllability at high altitudes (by implication around 35,000 ft) is also assessed as poor.

Soviet results, confirmed by Yugoslav comparative examinations (oh, yes – we have tested that cute little thing too!) are indicating 14.758 meters as a completely accessible value. On the other hand, absence of the pressurized cockpit has certain advantages – absolute nonappearance of the explosive decompression, potentially highly probable in air combat.

#66

So the absolute ceiling is improved. What about controllability, stall margin (i.e. gap between Vne and stall speed), etc.? A big engine will get you to very high altitudes, but it takes a great deal more than just power to do anything useful up there. The other issue is pilot skill - many aircraft require extremely accurate flying at or close to their ceiling, and most pilots aren’t capable of this. Something as simple as firing guns can cause the aircraft to lose control and stall severely.

Err… sort of. They increase the fuel tankage, but they also either increase the wing loading (drop tanks) or total drag (towed wing tank). Either will reduce the service ceiling radically until dropped, and marginally afterwards (additional plumbing, etc.) The towed tanks in particular would be a major handicap if the aircraft suddenly came under attack…

Quite impressive actually - that’s a longer burn time than the Me-262.

Was this an actually planned mod? What does it do to the empty weight and centre of gravity of the aircraft? Any increase in empty weight will translate directly into a lower ceiling and make controllability harder at any given height.

At altitude??? I’m not aware of ANY aircraft using these for anything other than takeoff/landing, so if you are aware of any I’d love to see them. I’d be rather surprised if they were used though - they increase drag coefficient faster than lift coefficient (or else they would be used in the cruise condition) and aircraft close to their ceiling need every drop of power they can get.
<spot the frustrated aerodynamicist!>

It is also by far the best bet of the German WW2 aircraft to be able to reach the altitudes required - relatively high power to weight, not reliant on an engine that never worked and a big wing. So far as I’m aware nobody ever tested one at reasonably high altitude however, and until they do I’m going to reserve judgement about exactly how manouverable/controllable it would be. There are some very good reasons flying wing designs haven’t proved popular despite their advantages for the internal volume/wetted area ratio.

Quite right -I was thinking of the standard P.1160!

The problem with WW2 Germany is that the line between the two often became surprisingly blurred, particularly when it came to late-war designs. An awful lot of the German designs of the time were full of advanced concepts - and full of bugs in the advanced concepts that the Germans simply didn’t know existed.
Swept wings are an ideal example of this - the Germans (and indeed everyone else for that matter - the original research into them was published before the outbreak of war) knew that they reduced transonic drag substantially and enabled the use of a thicker wing section. Great! What they didn’t realise - and what caused the US, UK, Soviet Union, etc. so many headaches postwar - was how badly this affected the stall performance of the wing. To this day the Hawker Hunter is the ONLY swept wing aircraft which can safely be spun and recovered (which is why the ETPS at Boscome Down is the only place on earth to teach it). Just to fly a swept wing aircraft safely requires a whole pile of aerodynamic fixes - wing fences, turbulators, wing twist/aero-isoclonic wings, fly by wire, etc. It took several years postwar to work out what the problem was and come up with the appropriate fixes - time the Germans both didn’t have and weren’t planning on needing.

Oh, I’m not doubting at all that a suitably equipped test pilot (in a pressure suit, having been pre-breathing a pure oxygen atmosphere for some time) can get an aircraft like that to such a height - it’s got thin, straight wings and a fairly high power:weight ratio with a low wing loading, so is an ideal candidate. That isn’t the same as being of any use in combat at that height however - the US report makes it fairly clear that the manouverability margin at that altitude will be very small making fighting it hard, particularly for a less experienced pilot. The requirement for a pressure suit - particularly if you need to pre-breathe oxygen - makes scrambling it in the face of an attack a very slow process. All in all I have doubts as to exactly how effective an aircraft like that would be against the B-36 - an intercept is theoretically possible, but in the face of an aircraft trying not to be intercepted/shot down…?
Of course, if you offered me a free one as a toy I wouldn’t say no :wink:

#67

If you have a basis knowledge of math look at http://en.wikipedia.org/wiki/Talk:Holodomor, and discussion so you can figure out yourself. Margolis’ figures are ridiculous, it’s really complicated matter to comment.
For me each human life is equally important, but using figures in this way is really painful.

#68

What about controllability, stall margin (i.e. gap between Vne and stall speed), etc.? A big engine will get you to very high altitudes, but it takes a great deal more than just power to do anything useful up there.

With appropriate tactics that is not a problem, my dear Mr. Pdf 27 – the only thing we have to do in this case is to apply the good old advantages of the so called vertical plane maneuvers, directly dependable by our speed. For example, we are starting our attack in ordinary level flight, at cca 6.000 meters, being directly under the bomber formation, with no less then 650 km/h of airspeed. In that moment we are dropping all our additional tanks, we are activating our rocket booster and we are pulling back the stick. All our engines are at maximum and our machine is now getting almost a 90 degree nose-up pitch attitude (meaning we are pointing straight up in the enemy formation!). If enemy formation is passing above us, or already is above and in front of us the only thing we have to do is to stop pulling the stick! After that we are already inside the effective range, and we are capable to fire our salvo of R4M rockets. If something is directly in front of us it will be blown to the Kingdom Come - if not our speed is high enough to bring us above our slower enemies. Arriving at circa12.500 meters, and still with great reserve of speed we are commanding a simple 180-degree roll. In addition, this time, when we are at the top, we have gravity’s help on our side! :smiley:

Err… sort of. They increase the fuel tankage, but they also either increase the wing loading (drop tanks) or total drag (towed wing tank). Either will reduce the service ceiling radically until dropped, and marginally afterwards (additional plumbing, etc.)

Absolutely, my dear Mr. Pdf 27. But aforementioned facts never represented some kind of a impenetrable barrier for numerous other airplanes in the WW2. Why our unfortunate Me 262 should raise an exception? By my personal opinion, those tanks are representing an completely realistic technical opportunity, and not an impenetrable restriction.

The towed tanks in particular would be a major handicap if the aircraft suddenly came under attack…

Oh, dont worry, my dear Mr. Pdf 27 – our brand new, freshly installed air defense system “Egerland”, built by renowned Telefunken, with panoramic aquisition radar “Kulmbach” and the agile gun laying radar “Marbach” capable to achieve semi-automatic homing on the chosen target, will prevent those attacks! :smiley:

Was this an actually planned mod? What does it do to the empty weight and centre of gravity of the aircraft?

Yes, actually it was! As early as October 8th, 1944 Messerschmitt design bureau presented the calculation for a new version, designated Me 262B-2a. That airplane had a extended fuselage by means of inserting that previously mentioned 1.15 meters long section in the centerplane, with fuel housed in six interconnected tanks. This innovation allowed an increase in the available amount of jet fuel to 3170 liters, allowing the airplane to fly continuously with internal reservoirs only for 130 – 145 minutes.

At altitude??? I’m not aware of ANY aircraft using these for anything other than takeoff/landing, so if you are aware of any I’d love to see them. I’d be rather surprised if they were used though - they increase drag coefficient faster than lift coefficient (or else they would be used in the cruise condition) and aircraft close to their ceiling need every drop of power they can get.
<spot the frustrated aerodynamicist!>

With pleasure, my esteemed colleague! You see, during the last fifty years fluid dynamics has become indispensable in the solution of numerous problems associated with aviation. However, a regrettable consequence of this is that numerous advances in the field of aerodynamic have become too numerous for one person to be able to survey them. I think that there is a pressing need for surveys of the forgotten branches, and as a scientific librarian I am completely willing to help with that knotty issue. :slight_smile:

So sorry, honorable ladies and gentlemen – that annoying message is here again: The text that you have entered is too long (11446 characters). Please shorten it to 10000 characters long. Oh, well… :roll:

#69

As you know, my dear Mr. Pdf, the simplest method of increasing the maximum lift of a given surface is to increase the profile camber by deflection of a flap. The possible ways of fitting a flap on to a profile are numerous, and the effects on the profile properties are extraordinary varied. The principal arrangements are:

  • plain flaps
  • split flaps
  • slotted and multi-slotted flaps, and
  • nose flaps

In addition, the most diverse combinations of these arrangements were and still are used for numerous, different purposes.

The maximum lift of plain flaps depends essentially upon the ratio of the flap chord cη to the profile chord c, as well as the flap deflection η. Ratios cη/c that lie in the range 0.2 to 0.25 are favorable when η is about 60 degree, and the increased maximum lift rises with thickness. For laminar profiles the range of Cl in which the drag is small can be displaced to higher Cl values by small flap-deflections (a small camber has the same effect). But as with a ll flaps it is essential that the unavoidable gap between wing and flap be kept as small as possible – otherwise losses in lift cannot be avoided, and drag will be increased too!

But why is this so important? Because the increase in the moment coefficient ΔCm (usable for maneuvering!) is directly proportional to the increase in the lift coefficient ΔClmax.

With a split flaps the suction side of the profile remains unaltered, but on the pressure side a downward flap-deflection is possible at the rear. The effect is similar to that of a plain flap, but considerably more marked.

A still higher lift-coefficient can be obtained by the use of the slotted flaps, but the geometrical shape of the slot must be carefully considered if the desired increase in lift is to be realized. For this reason sharp edges at the beginning of the slot are to be avoided as much as possible on relatively thick profiles, like in this case with our dearly beloved Ho 229 (thin profiles are less sensitive in this respect).

German engineers were well aware that only a limited increase in lift without a drag can be obtained by arrangements of flaps. Their conclusion was that to gain a further increase the distribution of energy in the boundary layer must be controlled by suitable means – either by sucking away the fluid in the boundary layer near the wall (that fluid is deficient in energy) or by blowing out compressed air in the direction of flow – that is, by bringing in additional energy!

Impact of blowing upon aerodynamic characteristics of a wing with double-slotted flaps

The German war experiments with blowing as a mean of increasing the lift, started in 1938 and were concerned with the generation of a high lift utilizable with different transonic profiles toward enhancement of maneuverability in critical flight paths (Schwier, W. : Versuche tur Auftriebssteigerung durch Ausblassen von Luft an einem symmetrischen profil mit Wölbungsklappe groβer Tiefe, FB 1462 – 1941). Schwier has investigated an arrangement for blowing, which was fitted to a profile with a slotted flap. Air was blown out over the flap through a slot at the trailing edge. The results were better than those obtained with the corresponding arrangement using suction and a plain flaps.

Different variants of the compressed air streaming over flapses

In his capital work W. Krüger (Rechnerische und experimentelle Untersuchung zur Frage der Förderleistungsbedarfes von Flugzeugen mit Grenzschichtbeeinflussung, FB 1618 – 1942) proved with his measurements for small values of the volume-flow rate that there is only a tiny change in lift (assuming the angle of incidence is kept constant), but also that lift increases rapidly if the air blown out has approximately the same speed as the flow, and that the narrower the slot – the more effective the blowing is. Additional gain is achieved in drag reducing.

Another form of blowing that results in an increase in CLmax, but which does not directly influence the boundary layer, is the blowing of a jet of air out of the profile on the pressure side (a proposal of Betz, 1943). This produces an effect similar to that of split flaps, ut without a significant increase in drag as well.

Other significant German works in this domain are:

“Ausblaseversuche zur Auftriebsteigerung an einem Querruder geringer Tiefe”, FB 1579 – 1941
“Ausblaseversuche zur Auftriebssteigerung an einem Flügel von 9% Dicke mit Vorflügel und Klappe” , FB 1622 – 1942
“Versuche über Wiederstandsänderungeneines Tragflügels beim Ausblasen von erwärmter Luft”, FB 1783 – 1943
“Blaswersuche zur Auftriebssteigerung am Profil 23015 mit verschidenen Klappenformen” FB 1865 – 1943
“Auftriebsänderung durch einen auf der Flügeldruckseite ausgeblasenen Luftstrahl”, UM 3192 – 1944.

And that’s only the beginning of the story, my dear Mr. Pdf 27 – American experiences from mid-fifties are much more remarkable! For example, those connected with a legendary machine, indeed one and only North American RA 5 C Vigilante. Just ask our American colleagues here – they surely do have much more materials! In the mantime I shall try to prepare something about Soviet developments!:wink:

It is also by far the best bet of the German WW2 aircraft to be able to reach the altitudes required - relatively high power to weight, not reliant on an engine that never worked and a big wing.

Absolutely agreed, my dear Mr. Pdf 27 – that airplane is my machine of choice as well!

Ho 229 – data table

That isn’t the same as being of any use in combat at that height however - the US report makes it fairly clear that the manouverability margin at that altitude will be very small making fighting it hard, particularly for a less experienced pilot.

The main question in this case is what kind of a maneuverability actually is needed, My dear Mr. Pdf 27. Are you suggesting that a fully loaded B36-A Peacemaker is capable to perform a Hammerhead or the Cuban Eight up there at 11.500 meters? :smiley:

The requirement for a pressure suit - particularly if you need to pre-breathe oxygen - makes scrambling it in the face of an attack a very slow process.

Oh, not at all if your forces are equipped with a mobile, reliable, 260 kg heavy, 2,2 meters long, single-person hyperbaric chamber, with internal diameter of 0,65 meters – otherwise completely transportable by a standard 1,5-ton army truck and completely independent from outer electric power sources. And we still do have those remarkable Soviet things here. :wink:

Of course, if you offered me a free one as a toy I wouldn’t say no.

Good, my dear Mr. Pdf 27 – but please remember that I am a really playful personality as well! Therefore please moderate yourself: you have only three circles for free! :wink:

#70

It’s hardly anything unique to the -262, rather it’s generic to all aircraft close to their ceiling - additional weight or drag cause major handling/ceiling problems.

OK, in that case they probably did a halfway decent job of it. Rather a lot of the late war German designs were very much “back of a fag packet” designs whcih were taken seriously due to the desperate situation Germany was in by then.

To be exact, for any sensible wing design NO increase in lift can be gained without an increase in drag, and the L/D ratio will always get worse when you deploy flaps. If it didn’t, then the aircraft would have the flaps deployed permanently as it would allow the generation of the same amount of lift from either a smaller wing (hence less wetted area) or at a lower AOA (hence bigger manouver margin). Blown flaps sometimes improve the L/D, but that is if you ignore the effective loss in engine power caused by the blowing system. If you add this in (and you can easily be taking 10% of the air from the HP compressor to run the blowing system) your effective drag goes way up. Essentially, blown flaps are NOT a solution to improving the absolute ceiling of an aircraft due to the engine power loss, which makes the effective L/D worse and hence reduces the ceiling. You could add an engine specifically to provide this air (indeed, there were proposals for a pressurised variant of the Avro Lancaster with a fifth engine in the bomb bay to drive a supercharger to feed air to the engines - very similar to this in concept, and probably intended as a nuclear bomb carrier if the Tube Alloys project ever came to fruition) but this adds a substantial amount of weight and the benefits probably aren’t big enough to be of any use.
At this point it’s worth looking at what worked postwar for getting to extreme altitudes - essentially you have to go very fast and have very high specific power. You can compensate to an extent by using very big wings and light weight (e.g. the U-2 spyplane, B-36, English-Electric Canberra, etc.) but to get to very great heights you need extremely high specific power and to get there in a zoom climb at supersonic speeds.

Hardly - but given that it had very big wings, a lot of fuel and high specific power it may have been able to turn inside a fighter aircraft. For instance, the Avro Vulcan (while it looked very different, it had the same advantages - big wing and high power) was quoted by the RAF on entering service as “being able to out-fly and out-turn any operational fighter on earth at it’s operating altitude”, or words to that effect. The point I’m trying to make is that at very high altitudes your manouverability is very, very limited indeed - and that big aircraft don’t suffer quite as badly from this.

Are you serious? The Soviets seriously expected their pilots to try and make an intercept while suffering from the Bends, and were going to treat them when they got back down again? Jeepers!

#71

Oh this is whole scientific article you have wroet dear Labrarian.
I’m wondering of your ability to find and expound the matter.
This is so amazing for humble labrarian:)
As Rising Sun said , you know TOO much , my dear friend:)

The main question in this case is what kind of a maneuverability actually is needed, My dear Mr. Pdf 27. Are you suggesting that a fully loaded B36-A Peacemaker is capable to perform a Hammerhead or the Cuban Eight up there at 11.500 meters? :smiley:

He he
You are right mr Librarian ( as alwyas, well most of times)
Strange but our friend PDF has an very jealous relation toward the GErmans military/technological/science achievements. Why is so i don’t know
We both ( Russian and UK) fought with GErmans, but our british friend seems has tend to underestimate the GErman ability to creat the hight-tech vechicles.
This is probably of matter of their European national proudness - to competite with GErmans?French in every field, even in forums battals…
But who know, may be PDF is right.( i mean to be hard in technical disputes)

Oh, not at all if your forces are equipped with a mobile, reliable, 260 kg heavy, 2,2 meters long, single-person hyperbaric chamber, with internal diameter of 0,65 meters – otherwise completely transportable by a standard 1,5-ton army truck and completely independent from outer electric power sources. And we still do have those remarkable Soviet things here. :wink:

How did you used it exactly?

#72

No secret about that - I just think they’re massively overrated. People see all the advanced concepts and see that they didn’t come into service use until several years postwar in the Allied countries - which causes them to make the assumption that the Germans were ahead. The problem with that is simple, and twofold:

  1. The Allies had a realistic estimate for how long the war would take, and so didn’t introduce super-advanced designs that wouldn’t be in time to take part. This is one of the reasons why pretty much throughout the war the Allied aircraft were usually that little bit better than the Germans - the Allies didn’t try to jump a technological generation, and always worked the bugs in an aircraft out before it went into service. The Germans had problems with both.
  2. The immediately postwar years were spent by the various Allies fixing the truly horrendous bugs associated with most of the advanced concepts (bigger jet engines, afterburner, swept/delta wings, etc.) and getting through the sound barrier. The net result is that the visually similar Allied designs were an order of magnitude more capable than the German ones.

In that case, why am I relaxed about saying that the Americans were (mostly) ahead of the British in aircraft? It isn’t national pride but engineering judgement (I should probably point out at this point that my MEng is in aero engineering, mainly in jet engines and transonic aerodynamics, even though I now work on vacuum pumps).

#73

additional weight or drag cause major handling/ceiling problems.

Those problems are completely insignificant if weight and drag are compensated with a powerful additional thrust, as in our case. If I may remind you, the weight of the rocket engine HWK 109-509.S2 was 140 kg, but the thrust was rated at 2000 kg.

To be exact, for any sensible wing design NO increase in lift can be gained without an increase in drag…

The only problem in this otherwise theoretically completely correct statement is the word “sensible”, my dear Mr. Pdf 27. You see, if we are sufficiently willing to correlatively apply suction as an additional mean of reducing drag in our multi-slotted construction, and if deflection angle is only 10 degrees, we will be able to produce a stationary small vortex within the slot entrance. Such a vortex consumes very little energy, provided that the outlet of the slot is effectively closed. Furthermore, it has even been found possible to make the boundary layer stay completely laminar by a special design of profile, which leads to a pressure distribution favorable right to the trailing edge (with the exception of the slot itself).

Holstein and, independently, Ackeret, Rash and Pfenninger were the first to demonstrate that gains in performance, which are of completely practical value, can be realized, but the number and position of the simultaneously operated suction slots must be very carefully chosen.

Measurements of Holstein on the Kármán-Treffz Profile 0015, with additional suction to keep the boundary layer laminar

On the other side, my dear Mr. Pdf 27, drag is - together with his companion lift! - actually a very usable assessment for our authentic purposes – significant enhancement of the combat agility, or more precisely sustained turn rate of our aircraft! You see, our favorite basic design – Ho 229 A-1 has an absolutely adequate ceiling - 15.800 meters. However, we were told that those bad and mighty B 36 bombers are able to somehow outmaneuver us up there in some kind of a dogfight… However, we will see that this assumption is utterly wrong!

Blown flaps sometimes improve the L/D, but that is if you ignore the effective loss in engine power caused by the blowing system. If you add this in (and you can easily be taking 10% of the air from the HP compressor to run the blowing system) your effective drag goes way up.

Completely artificial dilemma, my dear Mr. Pdf 27. Why you are so overwhelmed with that pitiful failure of the Hunting H.126? First of all, we have an already available direct method for missing air-mass compensation in our pockets – an afterburner. It was already envisioned in 1945 (Junkers Jumo 004 E). If properly calculated, afterburner will be able to compensate that missing air in the time of need.

On the other hand, additional methanol-water injection in those jet-exhaust gases in the very moment of need, in a minute when we are using that previously mentioned pressurized air for our flapses (while maneuvering), is completely capable to create a larger mass-flow rate as well and to compensate compressed air losses - in this way we are adding extra mass to the already existing mixture of produced gasses.

In addition, the steam that is produced is cooler, therefore additional thermal stability of the nozzle alloy is achieved too. Not even to mention that from a thermodynamic point of view that exhausting hot gas possesses a huge amount of unused heat energy, and thus a lower fuel efficiency. With our little device, a variant of the well – known MW 50 system, that problem is properly treated as well.

Of course, other possibilities are available too – engine shaft-driven rotary screw compressors, pyro-fluidic generators/amplifiers, highly pressurized pre-compressed gasses, pelleted solid-fuel thermo-jets, etc, etc. are completely available as well.

Essentially, blown flaps are NOT a solution to improving the absolute ceiling of an aircraft due to the engine power loss, which makes the effective L/D worse and hence reduces the ceiling.

Yes, my dear Mr. Pdf. You are right. But who ever talked about the absolute ceiling, if I may ask you? Ceiling of the Ho 229 A-1, as already mentioned, is excellent (yes, I know – theoretically!). The only problem emerged when we were told by you that our maneuverability actually would be a problematical subject during the battle. That is how everything started. Theoretically completely available and utterly rational solution (offered by little me) were flaps – those incredibly useful devices, capable to increase the area and chord of the wing, thereby increasing lift in critical moments of every flight - at lowered speeds, therefore in maneuvers too. They always were capable to help us with landing, takeoff, climb, and in maneuvers as well – in all those problematical conditions when our desire was to slow down a little and to still stay in the air. That’s all.

And yes - the proper use of the multi-slotted blown flapses is able to assure a victory for us in that coursed, never appropriately analyzed and provisorily fabricated aerial battle. Theory suggests that since flaps increase lift, they will increase our turn rate in the steeply banked turns as well, and those turns usually are used in every mid-air combat.

You could add an engine specifically to provide this air (indeed, there were proposals for a pressurised variant of the Avro Lancaster with a fifth engine in the bomb bay to drive a supercharger to feed air to the engines - very similar to this in concept, and probably intended as a nuclear bomb carrier if the Tube Alloys project ever came to fruition) but this adds a substantial amount of weight and the benefits probably aren’t big enough to be of any use.

Sorry, my dear Mr. Pdf 27, but that solution actually represents a complete devastation of those beautiful thrust/weight potentials. In addition, your Lancaster actually used a completely known, old solution for augmentation of the piston engine power capacity by means of additional pressurized air supply via separate compressor, driven by an Otto-cycle motor. As a matter of fact, that solution was pioneered by the USSR in 1936 with the ANT 42 prototype, and successfully followed by the French Air Force in a so called Bi-Tri moteur solution, applied in 1939 by S.N.C.A.C (Societe Nationale de Constructions Aeronautiques du Centre – previously “Farman”) on their marvelous project NC-150.

End of Part I. To be continued soon.

#74

Hardly - but given that it had very big wings, a lot of fuel and high specific power it may have been able to turn inside a fighter aircraft.

How exactly, my dear mr Pdf 27? As far as I know wing area of the B 36 was 443.3 m², and its loaded weight was 120,700 kg. Specific wingload – the most useful measure of the general maneuvering performance of an aircraft - in that case was 272,276 kg/m².

On the other hand our tiny little toy, Yak 23 Flora, possessed a wing area of 13,50 m², as well as a loaded weight of 3,384 kg, thus producing wing loading of only 256,666 kg/m².

Therefore tell me, please what kind of a energy equation in its own maneuverability is applying our dearly beloved, high-altitude untouchable marvel-weapon (otherwise truly amazing and highly impressive airplane!)?

Are you serious? The Soviets seriously expected their pilots to try and make an intercept while suffering from the Bends, and were going to treat them when they got back down again? Jeepers!

No, my dear Mr. Pdf 27. They did just the opposite - they used (and we still do use!) those devices for a preventive pure Oxygen pre-breathing. Please, look:

Mobile baro-chamber – large type, YAF, 1953

Interior of the previously shown large, multi-compartment mobile barochamber, YAF, 1953

Operational airplanes were situated nearby, within some 25-30 meters.

How did you used it exactly?

In a few different ways, my dear Mr. Chevan, but mainly:

  • For a moderate in situ oxygenization (45 minutes) capable to promote the washout of Nitrogen from body tissues via low pressure-breathing of pure O2 before ascent to altitude, which was capable to significantly reduce the risk of altitude DCS and scotopic sensitivity for a moderate exposures (30 – 60 minutes) to altitudes up to 13,000 m;

  • Physiologycal training for the high-altitude missions (18.000 – 20.000 meters), scafander presurization and sealing testings;

  • Prolonged physiological pre-flight preparation, involving augmentation of of the resistivity of the body to hypoxia;

  • Increasement of the gas-filling of pulmonary tissue for the prolonged missions above 15,340 meters with additional Mexamine intake;

  • Prolonged exposures of combat personall to artificial gaseous environments with 90-94% Oxygen at a pressure corresponding to the altitudes 7 – 10 km;

  • Medical examinations connected with vital capacity, heart and respiration rates, arterial pressure, body temperature and weight, elastic properties of the lungs, bronchial permeability, breath holding, composition of alveoler air, total water loss, volumes of extracellular fluids, morphological composition of blood, indices of redoxprocesses and acid-base equilibrium, etc.

Old, but even today completely functional Soviet-made barochamber in operational use – YAF, 1998.

Oh this is whole scientific article you have wroet dear Labrarian.

Thank you, my dear Mr. Chevan – but if truth is to be said it is not a scientific work, it is merely a simple, properly undertaken investigative task. In this very minute, for example, I am analyzing and translating certain parts of that magnificent book of N. V. Krasnov – (Н. Ф. Краснов, Аеродинамика Часть 2 - Методы аэродинамического расчета). You know – something about those mathematical and experimental marvels discovered by the idiotic TsAGI. I somehow do feel that those talented but too often brusquely ridiculed Soviet peasants - otherwise intelligent and sometimes uniquely great in higher mathematics - are requiring some kind of a… just, or fair intellectual protection. That will be my personal tribute to them. And symbolic representation of my personal reasons for doing that is presented here:

If nobody else, I am sure that you will understand me, my dear Mr. Chevan. Words are not always the best way of interpersonal communication.

I should probably point out at this point that my MEng is in aero engineering, mainly in jet engines and transonic aerodynamics, even though I now work on vacuum pumps).

Nice to meet you, my esteemed colleague – on the other hand I am just a simple enthusiast, with an LLM in the Law and a Master’s degree in Organic Chemistry. Am I satisfying those special scientific conditions for a sufficiently methodical and matter-oriented dialogue?

More seriously, and completely honestly, my dear Mr. Pdf 27: I have to admit that I was frequently exceedingly surprised with certain manifestations of your factual unawareness in certain things. Maybe it really was a non-conscious manifestation of your anti-Nazi or perhaps latent anti-German inclination, as previously mentioned by Mr. Chevan. Honestly - I don’t know. Please, PLEASE: don’t understand me wrongly – by my honor, I am not trying to insult you with these sincere words – by no means! God forbid! You are my co-worker here and I really do respect you. But how on Earth is it possible that a highly educated British aeronautical engineer knows nothing – or perhaps just pretends! - about a verity that the pride of the British jet engine engineering – the Rolls Royce Derwent - actually used air cooling for his main shaft bearings? Alternatively, that thermal recuperation in jet engines was and is not only a completely achievable technical solution – furthermore, a luminary point in our contemporary engineering efforts! - but an everlasting merit of the British engineers? Or that Nickel really is an important participant in those light thermo-resistant aluminum alloys? Or that resident nuclear radiation still exists in Hiroshima… Simply, I don’t know…:frowning:

If self-sufficient, completely independent, sacrosanct scientific truth – that very last unaffected, undiluted and praised value of our common, Western civilization – is so highly appreciated by you as well, my dear Mr. Pdf 27, then I beseech you, in the bowels of Christ, think if possible you may be mistaken! And don’t worry – this old-fashioned scientific fool always will protect those true, everlasting merits of the British engineering. If you wish, I shall start with those magnificent Fairey – Youngman flaps.

May God almighty bless you and keep you.

#75

Indeed, the fitting of an afterburner/reheat stage is precisely what enabled the MiG-17 to reliably intercept the B-36 and made it obselete practically overnight. It was hardly a new concept - Whittle had a prototype running in 1945 which he intended to go in the Miles M.52, but getting them to work is a major pain in the backside. Getting reheat stages to work reliably took a surprisingly long time - although it becomes very undertstandable when you compare flame propagation speeds to gas flow speeds in the tailpipe. Come to think of it a Coanda jet works on pretty much this principle, although the gas speeds are MUCH lower which make it comparatively practical.

You missed what is probably the biggest advantage of the lot - throwing a fine mist of liquid down the compressor of a gas turbine engine means it will evaporate as it goes down the compressor. This effectively acts as a continuous intercooler, which cuts down the power requirements of the compressor significantly. Better still, it also increases the specific heat capacity of the gas flowing through the combustor/turbine significantly allowing you to burn more fuel for the same turbine inlet temperature and so increasing the specific power. The problem of course is that for this to be a significant advantage you need quite a big mass flow of fluid, which is why this is only really used in land based CCGT power stations nowadays.

Yeah, they’re possible. Are they a good idea?

Ah, OK. We’ve been talking at cross purposes. I was thinking of manouverability at very high altitude - at this point you’re going to be using your maximum available thrust, hence the value of L/D is more important that peak Cl.

Yes, if you have sufficient thrust not to stall. Normally not a problem, but at very high altitiude.

Oh, I’ve no doubt someone thought of it before. It was just the only example I can think of. And yes, it does kill the thrust/weight which is probably why it was never seriously developed in the end - might be worthwhile for a world record attempt or as a lash-up to improve high altitude performance at the expense of everything else (which I suspect that Lancaster was - if it was to be a nuclear bomb carrier they would have had to for it to survive the explosion), but not for general use.

#76

Hmmm… from the USAF pilots’ notes I posted earlier in the thread, at full load the B-36 had a wing loading of 77.5 lb/sq ft. This is at a weight of 370,000 lbs (168 tonnes), and gives a wing loading of 377.6 kg/m^2. Empty weight is 196,000 lbs (89.1 tonnes) giving a wing loading of almost exactly 200 kg/m^2.
Empty weight of the Yak-23 was 1.98 tonnes, giving a wing loading of 147 kg/m^2.
Hence, an empty B-36 will outfly a loaded Yak-23, while a full B-36 is totally stuffed (we kind of knew that anyway) and an empty Yak-23 can outfly it no matter what.

Going by your numbers, at full load, and aerofoils being equal (probably a good assumption) the Yak-23 wil have a lower wing loading and hence greater manouver margin.

Ah, OK. That’s a lot less unhealthy (and won’t affect them while at altitude) but the medium and long term health effects won’t be terribly nice.

For what it’s worth, I hold the Soviets as being a very great deal better at aero engineering than the Germans, even during the latter stages of WW2. After all, they actually solved the problems (by themselves, remember) that the Germans were just pretending didn’t exist.

Anyone who insists on someone being qualified to enter a debate is a fool. I was just trying to explain why I hold fairly “strong” views on certain matters.

I think it’s probably subtly different. There are a lot of fanboys out there (you may have noticed some recently) who think that everything German was super advanced, would have worked perfectly, etc. The Luft-'46 website is a good example of this - loads of sketches of super-advanced German concept aircraft. With the training I’ve had I can look at a lot of these and know that they’re really bad ideas - but people still keep claiming that they’re great. It think this is what is causing my reaction, rather than the Germans themselves.

Oddly, you’re in a better position than me to know things like that. My learning is very much driven by theory and application - how to solve a particular problem, what works, etc. The sad side effect of this is that I will often be unaware of what people have actually done in the past. Recuperators are a good example of this - I know why they work, what the thermodynamic advantages are, etc. and what the rough effects are in terms of weight, etc. for a modern engine. This explains my surprise at learning someone had actually done it in an aero engine - because I know that for reasonably modern engines it’s a bad thing to do. I’m standing on the shoulders of giants, true, but this makes it rather hard to see what the giant himself is standing on…

:twisted: I never was much of a fan of that chap :wink:

#77

It sounds like the “unknown holocaust” not the “forgotten holocaust” You know how those Russkies never wanted the truth out…

#78

Now tell me, boy, what is a “truth” that i never wanted to know?

#79

Ok Chevan
The Russians who exterminated millions of their own weren’t exactly running around the streets telling the world about it…Thats the truth boy…

#80

Don’t forget the Armeninans and the Turks. There is still controversy over this holocaust.