262 breaking sound barrier

T A GARDNER

The problem with your reply is that once again it highlights how unreliable is technical information provided by US sources postwar. Not wishing to give offence, but I have to say it: in my experience as a translator any Nazi internal technical document, particularly if supported postwar by a non-US aligned independent authority such as Poland, must be allowed more credence than a postwar US document, at least until such time as the contrary is proved.

I remember being warned by a publisher - in the case of doubt, always go back to the original documentation. From Mr Gardner and the sources below, we must draw the inference that either American intelligence was lying in 1945/46, or the documents upon which Mr Gardner relies are lying. We cannot have it both ways. Assuming that the original intelligence reports are honest, the original evidence is contained in these four references:

(102) W.Kozakiewicz et al, Bron Rakietowa, publ. Glowny Instytut Mechaniki, 1951 (classified until late 1990s)

(109) "Aerodynamics of rockets and ramjet research and development work at Luftfahrtforschungsanstalt Hermann Goering, Volkenrode": CIOS Report Item Nos 4 and 6, File No. XXVII-67 (1946). CIOS=Combined Intelligence Objectives Service.

(118) "Survey of German Ramjet Developments" CIOS Final Report, item No.6 File No. XXX-81.

(119) NARA/US Strategic Air Forces in Europe - Air Intelligence Summary No. 74 (8.Apr.1946).


"The American documents contain clear information about airborne trials(102)."

"...Professor Lippisch designed an aircraft resembling a bird's wing with ramjet propulsion. The prototype had to be modified continuously. The flying wind was to have a basic speed of 2500 kms/hr....to enable the aircraft to reach an adequate speed necessary to start the ramjet, solid propellant rockets were used....the speed was realized by the use of ATO rockets, the airflow heating the coal for more thrust. The hot gases flowed out through the narrow nozzles at the trailing edge. This solution enabled the thrust to be maintained for 45 minutes. In the final months of the war the propulsion effectiveness was doubled by injection of liquid fuel above the coal....." The last sentence means that the aircraft flew.

"The Lippisch P-13b was described in detail by the American analysts(19). Their drawings show little diference to the trapezoid version, also illustrated. Since the report mentioned at least two similar versions, it can be assumed that the differences are minor.

"In the American reports it was stated that the assembly was realized by various facilities of the LFW (Luftfahrtforschung Wien):
(i) aerodynamic tunnel at Tülln near Vienna
(ii) most elements were built at LFW Wiesenfeld
(iii) final assembly LFW Ramsau"

(iii) above means that the aircraft proceded beyond the wind-tunnel and was actually constructed.

"The American reports provide information about the fuel (described). The American source of information was cut off in early January 1945 when the prototype P-13b was ready for its first flight. Due to the fact that the Germans expected to achieve the magic speed of 2440 kms/hr, the Americans stated that there were many volunteers to make these historic flights."

WHY HAS THE UNITED STATES CONCEALED THE FURTHER PROGRESS OF THE LIPPISCH P-13B AFTER JANAURY 1945?

"Fortunately, the "gap" in the American documentation is filled by the 1951 Polish secret publication (102) (by the way the best analysis on German rocket weaponry I have ever read, and at the same time it is an official publication of the teams researching the German technology - almost 1000 pages - author's comment)."

"Take-off of the flying wing used ATO rockets from an oblique launcher...(describes device)...the thrust depended only on the temperature in the combustion chamber and aircraft speed....during the last months before the capitulation, it passed all its comprehensive trials. To double endurance, liquid paraffin was injected into the coals."


Either all this is in the Polish imagination, and the documents are falsified, or Mr Gardner is deceived by the US authorities upon whom he relies. I rather think the latter. The Freedom of Information Act in the United States exists so that investigators may discover "missing" areas of documentation "accidentally overlooked" by US agencies, which in this case include the last four months of P-13b trials before the capitulation.

 

So was this kept secret all the time?

 

Extraordinary claims require extraordinary proofs. This is the case here. Given the sources as being wartime intelligence reports without supporting photographic, physical, or postwar engineering data they appear as little more than evidence that some research was going on towards this project.
RE:

Why based soley on your opinion is one source better than another? Instead, a broad spectrum of sources would be far better than single sourcing something so extraordinary as to claim the Germans not only broke the sound barrier, but did so in the extreme (ie by as much as mach 2).
For example, the P13 weighs in at what fully loaded? Two tons? Three? We know from a broad spectrum of sources that solid and liquid fueled boosters used by the Germans generally produced about 1000 lbs / 500 kg of thrust for 10 to 20 seconds. These are types used with such aircraft as the Ba 349 natter or Ar 234 etc. A claim that somehow the booster rockets could operate for "45 minutes" given the evidence on every other German rocket system is absoutely absurd on its face.
We also know that for a ramjet to work at all speeds on the order of mach 2 are a minimum requirement.
The resulting physics here are that the boosters cannot alone reach the speeds necessary to operate the ramjet. In addition, we have the rather unique use of powdered coal as a fuel source. How was this delivered to the engine in flight? Being so unique, it is questionable that the system, whatever it was, operated without problems or technical difficulties particularly on a flying aircraft.

No, all this shows is that an airframe might have been produced and that windtunnel testing probably occured. There is nothing to indicate that the project proceeded beyond this on the above evidence.

The same thing here. There is no evidence given that an actual prototype was built. Given the late date in the war (Jan 45) it is even unlikely that a prototype existed at all. More likely, just basic mock ups for research and windtunnel testing existed.

Why a gap? Who knows? It is more likely due to the chaotic nature of Germany in early 1945 coupled with thlikely overrunning of the various testing and production sites. One can very easily predict that had the US or Soviets come in possession of an actual flying prototype of such an advanced aircraft it would have been tested and likely copied or improved on in early post-war test programs in either country as many other German advanced programs were. Yet, in neither nation is there evidence that such an aircraft existed. The volume of official documents alone means nothing.

Again, the generalities of the above are more in line with a description of a system in development than one in actually flying. Again, as stated above, the physics alone say that the system would not work. The Ba 349 weighing about 2 Kg at launch had nearly 4.5 Kg of thrust on launch to reach a theoretical speed of just mach .9 to .95. But, somehow, the P13 reaches mach 2+ on what? Look at the V-2! This project (the P13) somehow manages to accomplish more than double the thrust to weight ratio of anything else in the German inventory while sustaining thrust for far longer than any other rocket system. It is simply absurd on its face.

No, what it means is that the intelligence operatives reported what they heard or knew to the best of their ability. It is likely that few field agents were highly qualified to give accurate technical information or make decisions about the accuracy of that information rather leaving it to others to make. This has not changed all the way to today.

Yet, the claim made is based solely (at this point) on wartime intelligence reports. No supporting German techincal data has come to light. No physical airframes, engines, booster rockets, launch systems, nothing has been shown; be it photographic, actual materials, or other supporting tangible evidence.
The US, for example, tested dozens of other advanced German projects and weapons post war. All this evidence exists for these tests. Why not for the P13? The X-1 was still several years from flying in 1945. If the US had in their possession an actual working P13 would it not have been tested as every other German system was?

It seems the evidence only shows that the Germans were toying with the idea of the P13 in 1945 and nothing more. Until far more conclusive evidence can be produced I, at least, remain unconvienced that this project was nothing more than a paper and windtunnel test program that went nowhere.

 

Absolutely great quote Gardner! I'm enjoying this thread very much. You will have to search far and wide indeed to find such a technical discussion on a historical topic.

With all due respect Heavy Air, I tend to agree with the Gardner on this one. Looking forward to any further discussion though...

Peppy >>> likes the roots that Gardner planted

 

The flights by the Lippisch aircraft were those complained of by the Swedes overflying their airspace in the period December-March 1945. The flight path appears to have been from two mountain top sites in Norway across Sweden and from there to Poland. The US Lusty report stated that the US was in possession of a Lippisch supersonic aircraft.

 

I don't want to sound sarcastic here, really I don't, but do you Schwere Luft know how that claim sounds?!!
The Germans in early 1945 manage to manufacture a double sonic aircraft using a rocket motor to get it aloft, and then running this aircraft on powdered coal dust (possibly with parrafin added) using a ramjet engine. They build the aircraft in Austia / Southern Germany and then ship the finished plane to Norway were it is launched from a mountian-top site in Norway and flown across neutral Sweden back to Germany and, more than once!
Post war however, this whole project "disappears" with nothing more heard of it. Cover up? No. Didn't happen; Yes.

 

In the strictest sense, probablly not. Many interesting documents & other evidence lie about unknown just because folks interested in the subject dont know they exist. Also items published in the literature of one language frequentlly pass unrecognized by people who dont read that language. In other cases someone may write a artical on the subject, but it is never completed or the editors dont place it in actual publication.

Neither is it unusuall for documents like this to be used by one or more historians, then to be forgotton and neglected for several decades. Eventualy someone else "discovers" them and the evidence returns to public view.

Another common thing is when the published material on a subject is simplly forgotton. Back in the 1960s I read about these same aircraft and the transonic experiments in a aviation history magazine published in the US. Since any copies of that artical would be extremely rare its information effectivelly is lost.

 

While this (the loss of knowledge / information) does occur, in this case it is far more one of making what clearly is a very extraordinary claim; that is, that the Germans in early 1945 had a flying aircraft capable of exceeding mach 2.
According to what we know of the Lippsich project the aircraft weighed between 2 and 4 metric tons loaded. This would require a rocket booster given extant technology on the order of a small V-2 to get the aircraft aloft and to a speed where its ramjet would work. That is, the rocket alone would have to boost the aircraft to near mach 2 (say 2000 kph minimum, and more like 2500 kph) just to get the ramjet to run.
To complicate things powdered coal is used as a fuel. How was this stored and moved to the engine? Mechanical means such as a screw conveyor? Aeolian means?
There are just too many questions that pose huge obstacles to this project ever reaching a flying prototype, particularly in 1945 as Germany was collapsing. Think, when Kurt Tank describes a problem with the engine on a Ta 152 prototype requiring a replacement part and the only available means to get the part was to send a technician with special passes on a bicycle to the factory to get it and pedal it back taking a week to do so, as but one microcasum in the bigger picture of what transportation was like in 1945 Germany, it does not bode well that the P 19 could have progressed so rapidly to a flying aircraft....particularly given its novel propulsion systems and extreme predicted performance.

 

Don't worry, Terry, in the realm of www.luft46.com everything is possible

 

Sorry, but many ramjets work perfectly well at speeds as low as 200km'hr.
You are mistaking the higher efficiency of ramjets at supersonic speed for the idea that they need to go supersonic to work at all. That is far from the case.
They are far less fuel efficient at subsonic speeds than a turbine but they can still produce considerable thrust to propel aircraft at subsonic speed.
The Eugene Sänger designed Lorin ramjet and Skoda-kauber ramjets worked successfully subsonically. Both were fitted in separate tests to a Dornier 17 and were able to mightily thrust the unstreamlined beast to more than 150km'hr faster than its normal maximum top speed.
The P13 was intended to have a flattened version of these ramjets.
The French Leduc ramjet fighter had a derived version of the Lorin engine and flew under ramjet power in 1952 reaching a maximum sustained speed of mach .85.
So that's a large heavy german Dornier 17 being given a sizable kick along, plus a manned, working jet fighter prototype scooting through the sky and climbing under ramjet power only and there's no Mach 1, let alone Mach 2 anywhere in sight.
If the coal gas and catalyst system was airworthy, then a walter rocket could have easily helped a P13 reach ramjet operation speed.
Whether a powered P13 actually flew is another matter. Lippisch did successfully test the design in the Berlin supersonic tunnel and his freeflying test models worked beautifully. He later designed for Convair and his German colleagues led the teams that produced the Delta dagger, convair seadart and B58 Hustler.
Despite the bicycle factor mentioned, they still almost completed the sweep wing Me P1101, flew the Natter, DFS 228, flew 4 or 5 flights of the Horten lX (Go 229)version 1, flew the fieseler Reichenberg, the 4 engine Junkers 187, 4 engine Arado 234, TV guided missiles etc etc and fielded 3 types of Helicopters in Combat. A hypothetical completed p13 even if subsonic is in rather extraordinary company of genuine aircraft.

Btw The Münich computational fluid dynamics tests confirmed the ME262 could exceed Mach 1 for a few seconds without area rule. Not well or effortlessly but it was possible and the characteristics exactly match what was reported by Mütke and the British test pilots.
The engines flamed out of course during the transonic period and the plane needed previously to be dived steeply and with full power to minimise the duration of buffeting. A slow approach to Mach 1 would mean a long period of instability and severe down pitching leading to uncontrollable negative gs and loss of aircraft. After a few seconds above mach 1 with dead engines the craft would then drop back and begin shaking madly again with high deceleration and high likelyhood of structural failure and total loss of control. Not pretty, but still supersonic, even if only for a few brief moments.
Like the X1, the 262 had a fully trimable all moving tailplane rather than just an elevator flap. The 262 was tubby in the middle but had very thin swept wings. Similarly, neither the Bell X1, the F86 nor the Convair Seadart seaplane had area rule either but all were able to exceed Mach 1.

 

No it said the engine was made more efficient. They run these things on the ground many times before they put it in the plane.

Sadly no, it means that they had a plan to build the aircraft, much like the Me-264 mass production plan. It never happened but they had the plant to do it.

I would also like to point out that after January 1945 there were few living Germans in Poland.

Also anything can go the speed of sound, you just have to apply the proper amount of force. The area rule resulting in the coke bottle shape is not a law but a development and does not have to be used for optimal flight.

 

The engine would have to be tested in a wind-tunnel due to the airspeed startup requirements.
Rather than running the ramjet on the ground, I think it's also equally likely the improvements were part of the actual Dornier 17 aerial testing.

I think the other quote talking about the p13b prototype construction at various facilities most likely refers to the DM1 itself rather than a ramjet engine fitted p13.
When I return home from interstate I have a book devoted to the p13 and DM1 which documents the construction of the DM1 in detail. I'll post the results then.
Subscale versions of the p13 were definitely wind-kanal tested in flight configuration with the engine intake tube rather than just in DM1 deltawing configuration. Interestingly one of the photographs of the p13 undergoing string-tuft tests shows forward canard planes affixed to the nose intake. I imagine Lippisch was unsure about pitch behaviour and control during landing or flying near stall speed and added those as insurance. Once the deltas low speed behaviour was discovered he would have realised they were not necessary. The Eurofighter, Kfir, Griffon and Viggen were all deltas with forward canards.
Ordinary Deltas are of course rather forgiving at lowspeed and can fly approach with that remarkable nose up high orientation with the wing supported by enormous bound leading edge vortices.

 

First I am not trying to make you upset. Wind tunnels are usually on the ground. I am not familiar with the details of this project and it is possible that an engine of this type could have been fitted to a Do-17 I find it unlikely though. The engine would have to be center mounted, and if they got the engine running and tested it anywhere near where it needed to run for the P13 the Do-17 would fall apart. The 17 only goes around 500kph which is one quarter of the proposed operating speed. There is no benefit gained by testing it on a Do-17, at least not that I can see, now on a Me-262 or Ar-234 would have been more practicable.

I don't know of any super or trans sonic wind tunnels anywhere during world war 2.

I am not sure what you are trying to say here. That remarkable high nose up means that the plan is on the verge of stall and that if the pilot brings the nose down any he crashes. Delta wings are intended for use at supersonic speeds.

Looking forward to your details and response.

 

Um, why would I be upset answering questions and explaining things? It's fun!
Not sure why you find it unlikely that a large engine was tested on a large aircraft. The ram jets had huge thrust and needed lots of fuel.
The high drag , twin tail and sturdiness of the surplus obsolete Dornier made it the ideal expendable test bed for potentially self-destructing experimental engine. Much wiser than testing on a rare and valuable craft like an Arado or Me262.
Yes, a Dornier 17 goes 500km or so. With a ramjet it goes 650+ km'hr
If you understand the aerodynamic cube rule, that to double an aircraft's speed, the drag goes up by the square and the power goes up by the cube, or in other words to double your airspeed you need 8 times the power, such a large percentage increase in speed of a highly draggy aircraft at the low end of the ramjets operating speed range is highly significant. The ramjets were mighty powerful and they weren't even anywhere near their efficient speed range yet.
As a result of the succesful tests, special versions of the engines were planned to be trialed on Me262s and other craft.

Yup, the Lorin ramjets were indeed centre mounted over the back of the Dorniers.
The larger one shown is the Skoda Kauber, the smaller one the Sänger.






OK wind tunnels:
Allies: In June 1942 a 9inch diameter supersonic wind tunnel went into operation at the Langley Aeronautical Laboratory capable of Mach 2.5 airspeeds. By late 1945 an 8 by 6ft diameter tunnel capable of mach 2 airspeeds was in operation based on captured German tunnels.

Germany: supersonic wind tunnels were operational in Peenemünde, Aachen university, Friedrichhafen.
Dr Rudolf Herman designed the Mach 3.3 10cm x10cm tunnel at Aachen technical university, operational in 1937.
By 1938, two 40cm x 40cm mach 2.5 tunnels operated in Peenemünde by Dr Herman and Dr Kerzweg. After operation crossbow in 1943, the Tunnels survived unscathed but were transported by rail to Kochel in Bavaria.
Post war they were moved to White Oak MD along with 12 German technicians. the German scientists contructed the 16ft by 16ft tunnel and continued use of the Peenemünde tunnels and were all were used to design numerous American aerospace devices including the space shuttle.

Deltas can fly at extremely high angles of attack as the wing becomes engulfed by a massive bound vortex spiralling off the leading edge of each wing where flow separation takes pace. It is this energetic bound vortex that provides much of the lift at this AOA and represents what would otherwise be a fully stalled condition on a conventional wing. The extreme angle of attack possible by deltas is also a high drag state and deltas in combat lose velocity rapidly in high g turns without massive applications of power.
Your comment about if you push the nose down a delta will crash is not correct. Reducing the AOA will reduce lift somewhat but that is how lift is modulated. It doesn't mean that the delta will fall out of the sky.
Delta wings are not "intended for use at supersonic speeds".
They are a practical platform that incorporates a large wing area in a small wingspan and extremely strong structure. Some Deltas are good for supersonic speed , some are never intended to go supersonic.

Some deltas are capable of supersonic speed but the majority of deltas in reality spend most of their time subsonic.
Airforces usually don't fly their supersonic capable aircraft at supersonic speed for any length of time due to the enormous energy cost and noise.
The delta winged A4 skyhawk fighter for instance had a max speed of 1077km'hr and had decades of use. The delta wing Avro Vulcan bomber too did not fly supersonic.

 

It was not the size that made me think it would be unlikely but the speed. This prototype was designed to fly at 2000kph right? The engine is going to perform differently at 2000kph vs 500kph. I suppose that if they did not turn it all the way up and just wanted to see it fly then that serves a purpose but shot of that what was gained?

I understand that the engine would have to overcome drag to increase the speed, but that engine has the force to break the frame of that plane. Thats all I am saying.

I only got the first picture the rest did not display.

The German wind tunnels did not surprise me. Good for them and US.

Why does the delta shape cause a vortex at high angles of attack and what makes it bound? Usually the lift per aoa is not determined by the shape of the wing but by the airfoil. What about the delta makes this beneficial votex?

The delta compared to a swept wing of similar area is less efficient at speeds below m1. But are more efficient above m1 provided that the delta is inside the shock wave of the plane. I do not have my books with me and I am probably wrong but this is how I remember it right now.

Take a look at the pictures below and let me knwo which ones are deltas.

 

Excellent reading. The exchanges between T.A. and S.L. are riveting. But why is page 2 of this thread difficult to read ? It displays way larger than my screen..There is probably a lot of information that has not been totally revealed aboot German activity in high speed research. Were the Germans successful with coal fuel gas(have I got that right?) and if they were,then it makes sense that coal dust would be apart of their research..Maybe Big Oil doesn't want coal to be seen as an alternative, and has corked info on coal as an alternative to the oil problem?...forgive my naivety

 

I think you are making the assumption that these ramjet tests were exclusively to test an engine for the P13.
(BTW, right click on the missing pictures and select open in new window or tab to see them)
The tests were to develop operating ramjets and learn about them.
Remember that ramjets do not require supersonic speed to start. A myth that others have fallen for in this thread.
These engines and any aircraft they might later be mounted in would have to be started at a few hundred kilometres an hour and then be able to accelerate the aircraft to whatever its eventual top speed is. So worrying about how the engine operates at 2000+km an hour is a little premature.
It has to be able to get there first from lower speeds and obviously this would be the focus of development.

 

No need, coal dust is just like coal. It burns well, it is not a perfered fuel for most vehicles because you need to have a uniform fuel, and the ground up coal tends not to be uniform. Plus other issues. What is more common in vehicle fuels is the liquification of coal, this works well but is expensive. Not to mention that we have the same problems getting it out of the earth.

You are correct. Was it intended for other planes?

Okay I see where you are coming from now. Ramjets are not as efficient as normal jet engines below the speed of sound. At least then. So in light of the fuel situation I figured that they would only use them above that speed. However I can them as a way to get a plane that fast with out the time to develop the next generation of jet engines... Hum...

 

The problem with ramjets is that below the realm of about mach 3 they are inefficent. Below mach they are terribly inefficent. This is simply due to the low inlet air pressure at which they are operating. You can see how large the test one on the Dornier is. This is because volume and more fuel can make up to some degree the inefficency of low speed ramjets.
When I discussed these earlier I was infering that this inefficency was understood as a general principle and that any sort of aircraft that was going to use ramjet propulsion would have to rely on some other means of acceleration to a fairly high speed before starting its ramjet.
One only need look at how rare operational ramjets are in aircraft today. Between their inefficency at low speeds and their difficulty in being started to begin with (ie the requirement for an alternative means of acceleration) one can see that the whole concept is really not practical in an operational military aircraft.

Yes, the Germans were well ahead of the Allies in general in supersonic wind tunnels both in their theoretical design and their practical application. This did not however translate into any sort of useful military applications duing WW 2. This is simply a case of German engineers having exceeded the level of practical application and then not having been checked by operational need.
Essentially what I am saying is that experimentation on the edge of technological possibility in a wartime setting, especially one where you know (or should know) that you are an industrial underdog is really, really stupid. It is far better to quickly and ruthlessly concentrate your efforts on key extant technologies to win NOW against a logistically superior opponet.
This is exactly what the Soviets did. They pared their industrial output down to essentials and little else. They sought victory through quantity not quality. And, they succeeded brilliantly.

 

The supersonic windtunnels were used extensively in the German rocket and missile programs such as Wasserfall and the A4.
The Germans had built a number of devices capable of travelling more than 2800km'hr. The Windtunnel data allowing the Wasserfall to be able to maneuver at these extreme speeds.
The supersonic windtunnels were very useful for such developments but these programs themselves obviously had negligible impact on the war.
The Defensive wasserfall itself may have had a highly significant effect on the war if deployed in numbers against bomber formations and may have been far more effective than the Me163. The program was held back in favour of diverting resources to the A4 (V2) which appealed to Hitler's preference for offensive weapons and retaliation.
These devices had a significant impact on aerospace technology following the war.
Sänger who had designed the smaller of the ramjets shown above had windtunnel tested his silverbird hypersonic orbital skipper "Silverbird" which was intended to orbit the earth and drop bombs on any chosen target from space before returning from orbit. This project obviously did not get further development funding due to the enormous resources required but the performance of wings and controls were tested at high supersonic speeds.
Dr Sänger conducted tests of the powdered coal fuel at the DFS facilities
as did Dr Schwabl in Vienna (Vien)
Some details are mentioned in this Nasa publication from 1951 which states that Lippisch himself assisted further work on coal fueled ramjets for the US military. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930086622_1993086622.pdf
BTW, the windtunnel model of the P13 was tested at the supersonic windtunnel of the Aerodynamischen Versuchsanstalt in Göttingen in August 1944. It doesn't leave a lot of time to develop a full size working P13 by war's end if the Windkanal modell was being tested then but the Heinkel Salamander was developed in record time.
Lippisch had little to do with the finer details of construction of the DM1, which was largely being constructed by FFG München (Munich) facilities and at Prien on the Chiemsee.

Nice to hear T.A. Gardner you've come around on ramjets. A significant departure from the earlier statement "the rocket alone would have to boost the aircraft to near mach 2 (say 2000 kph minimum, and more like 2500 kph) just to get the ramjet to run."