Talk:Convair XF-92/Archive 1

First flight...
The article originally stated that the first flight was on 1 apr 48. However, Baugher states that the first hop was made later in the year. Obviously one of these sources is wrong, but which? Maury 13:16, 25 August 2007 (UTC)

The Convair XF-92 Page
This page seems to be cut. Can you please fix it? —Preceding unsigned comment added by 216.167.146.173 (talk) 23:04, 3 March 2008 (UTC)

Yeager's First Flight in XF-92
The "Operational History" portion of the article states that Yeager rolled the airplane upon landing. This is not true. The reference that was used for this statement was misinterpreted--actually Yeager rolled the airplane in flight, which was something Convair's test pilot would not do because the airplane was difficult to control (in his opinion). The incident in which the airplane was damaged on landing was during its last flight for the NACA, piloted by Scott Crossfield. The airplane had a landing gear failure which caused it to come to rest in the "comical" pose. The easiest-to-get-to reference for that incident is NASA Dryden's XF-92 online photo gallery. J79Thrust (talk) 05:02, 19 March 2008 (UTC)

XP-92
The change over to "F" designations didn't happen until mid '48. The original a/c was XP-92 and was the last "P" designation given to a fighter. There is a very good article on this a/c in one of the very early Air Enthusiast Quarterly magazine (no, I don't remember which one---my library was destroyed a few years ago) with a photo of the mock-up.--Phyllis1753 (talk) 16:35, 19 April 2008 (UTC)
 * Steve Pace's X-Fighters: USAF Experimental and Prototype Fighters XP-59 to YF-23 on p. 89 has two photos of the XP-92 mock-up which is weird-looking to say the least. The barrel-shaped fuselage had the cockpit buried into it with an intake surrounding the cockpit. FWiW Bzuk (talk) 23:07, 22 April 2008 (UTC).

Yes, that's the one. Good thing we didn't try to make the thing fly using coal for fuel as the Germans wanted to do. Met Lippisch once when I was in Coe College in Cedar Rapids, Iowa where he lived out his last years. Eccentric character!--Phyllis1753 (talk) 00:18, 23 April 2008 (UTC)

The searched Air Enthusiastic Quarterly is No.2. Here you can find at "Convair´s Delta Alpha" a good overview about the work for the XF-92. The designer of the XF-92 IS NOT Alexander Lippisch ! The Convair engineer-team was T.M. Hempill; R.H. Shick; F.W. Davis und A. Burnstein. Lippisch help only a handful days (!) with hints and most of this are not flowing inside the XF-92. (Henschel) —Preceding unsigned comment added by 217.87.126.27 (talk) 11:17, 15 February 2010 (UTC)

Relation to Lippisch P13
By some accounts, Convair designed a prototype, and then afterwards looked at Lippisch's work and consulted with him. Other accounts claim the XP-92 is based on the P13. It would nice to clear up that confusion. The XP-92 doesn't seem to look like the thick-winged stubby P13. DonPMitchell (talk) 04:56, 18 June 2012 (UTC)


 * Check out "The NACA, NASA, and the Supersonic-Hypersonic Frontier" by Richard P,. Hallion, which clears up a lot of misunderstandings. The wiki article definitely overstates the importance of Lippisch's work.  Vultee discovered his work later, and they did some tests of Lippisch's design, and found the thick wings were not suitable for supersonic flight. DonPMitchell (talk) 04:20, 25 June 2012 (UTC)


 * I've updated the article based on the NASA history article, replacing an unreferenced and very speculative paragraph that erroneously stated that the XF-92 was a modification of the P.13. DonPMitchell (talk) 18:04, 25 June 2012 (UTC)

Lippisch?
I'm sorry, but these changes are counter-factual. In spite of what Richard Hallion might claim, the historical evidence is conclusive: the XF-92 was inspired directly by Lippisch's designs.

The article now claims that Convair based their design on the work of Jones from 1944. The reference in question doesn't actually say this. What it does say, on page 246, is that the Convair design had more in common with Jones' designs. There is no explicit statement or even suggestion of a link between the two bodies of work. So this section of the article is wrong and appears to be SYN.

Nevertheless, Hallion does make the statement that "In contrast to popular myth, this aircraft and all the Convair delta aircraft that followed owed nothing to the delta wing research of Alexander Lippisch." He makes no effort to back up this claim directly (i.e., through notes about earlier developments at Convair). Instead, he simply states that the design was similar to Jones' (as above), and suggests that Convair came up with it on their own. He further states that the DM-1 was tested at Langley and found to have high drag, which I assume is implying that the XF-92's thinner wing was not related to this design.

So, that's Hallion's version. Now let us consider a contemporary resource from an extremely well respected independent 3rd party free of jingoism (emphasis added as needed):


 * "From the end of World War 2 crate-loads of captured German calculations and tunnel data on transonic wing design became available, and a considerable proportion of the latter also suggested a triangular, or "delta", plan-form. The problem was placed in the hands of Convair's Downey plant, with prime responsibility assigned to Adolph Burstein, the assistant chief engineer of the San Diego Division, and Ralph H. Shick, chief of aerodynamic research. These experienced men tentatively decided to recommend a delta wing for the new fighter. Most of the German material on such wings had stemmed from the Lippisch group.
 * Convair tracked down Lippisch at Wright-Patterson A.F.B., and Shick flew there to talk to the man himself. Shick came back to California convinced that the delta was the right choice, and his assurance injected a new spirit of enthusiasm and confidence within the company. Work went ahead during 1946 on what was then the only delta programme in the world."

This is hardly the only source making this statement, you can look here and especially here.

It is also worth pointing out that Hallion claims Jones' work dates from 1944, which seems to suggest it would have been available to Convair. In fact, the first paper on the “Properties of Low Aspect Ratio Pointed Wings at Speeds Below and Above the Speed of Sound” was published in May 1945, although dates in 1946 are also quoted. See this example for the more common 1946 date, and see this document for details of this development which claims both 1945 and 1946. The confusion appears to be due to which of the papers held which specific claims: according to Jones' own statement in the later document, the thin-wing work dates to 1945, but the paper on swept wing aerodynamics was delayed until the next year. See page 15. The first report was limited circulation and later release unlimited, as is noted here.

Long and short: Convair was inspired by the Lippisch work from WWI, was aware of the DM-1 work at Langley, and they did talk to Lippisch. I have no idea how Hallion came to his conclusion that this was a "myth", considering it took me 10 minutes of Googling to conclusively demonstrate he's wrong.

I will change the article, and add many of these new references. Maury Markowitz (talk) 17:22, 29 November 2013 (UTC)
 * It's also worth noting that a lot of "contemporary" references make those claims when, in fact, more modern scholarship has disproved them. - The Bushranger One ping only 04:55, 30 November 2013 (UTC)


 * Indeed, and if anyone has a source that disclaims any of the factual points raised in this, and many similar references, I'm all ears. But, quite simply, we have ample reason to believe this single source is simply wrong. Maury Markowitz (talk) 21:55, 30 November 2013 (UTC)

I have added several references to the DM1 article showing the evolution of the DM1 towards the original F-92 design concept while under testing at Langley. Maury Markowitz (talk) 15:57, 1 December 2013 (UTC)


 * I concede that I reacted too strongly after reading Hallion's chapter, but I think we have now swung too far in the other direction. It's not objective to dismiss Hallion as a "jingoist".  He interviewed Jones and researched NACA documentation.  So, in addition to Googling, I suggest we find and read his paper in _Aerospace Historian_ (March 1979) "Lippisch, Gluhareff, and Jones: The Emergence of the Delta Planform and Origins of the Sweptwing in the United States".  I think there is a risk that we are not telling the whole story. DonPMitchell (talk) 01:17, 1 April 2014 (UTC)


 * Also, it is not surprising that Jones' work was not published in the open literature until after the end of the war. The Air Force, NACA and the Aviation Industry would have been communicating through meetings and other private channels during the war. DonPMitchell (talk) 01:27, 1 April 2014 (UTC)

Specs?
Compare and contrast: Maury Markowitz (talk) 18:37, 1 December 2013 (UTC)

Gluhareff, Jones and Lippisch
I think this merits some more discussion, to make sure the article is balanced and not falling into a popular trope about Nazi inventions. Here is what the historian Jacob Neufeld had to say in "Technology and the Air Force: A Retrospective Assessment"


 * Inspired by the earlier work of émigré Russian engineer Michael Gluhereff transmitted to the NACA via glide bomb contractor Robert Giswold, Jones conceptualized the low aspect ratio, low thickness/chord ratio delta wing as a potential solution to the problems of supersonic and transonic flight. In Jan 1945, he discussed this work with Ezra Kotcher, who brought it to the attention of von Karman and one of von Karman's chief assistants, Hsu-schen Tsian. By May, Jones had flight tested a model mounted on the wing of a diving P-15 Mustang. He next explored the sweptwing configuration, with a test model of it undergoing study late in May 1945, still well in advance of German sweptwing data reaching the United States.  The myth of German omnipotence in swept and delta-wing research, unfortunately, continues to thrive."

Neufeld references Jones' reports dated May 11 and June 23 1945. He also cites a memoirs by Jones, and von Karman.

So I think we must seriously consider that Hallion's research is correct, and that Convair and the Air Force were aware of this work by Jones when they submitted the XP-92 proposal in October 1945. Keep in mind, an aircraft design proposal takes some time, so they had to be working on knowledge from a month or two before that date.

Here is what Hallion has to say about Gluhareff, based on a July 1941 memo he found at the Smithsonian. See his article "Sweep and Swing: Reshaping the Wing for the Jet and Rocket Age" here ( http://www.nasa.gov/pdf/482993main_ContributionsVolume1.pdf )


 * In 1936, Michael E. Gluhareff, an émigré Russian engineer who was chief of design for the Vought-Sikorsky, began examining various tailless aircraft configurations. By July 1941, his study had spawned a proposed interceptor fighter powered by a piston engine driving a contra-rotating pusher propeller.  In a rounded delta planform resembling an arrowhead, with leading edges swept aft at 56 degrees. ... Gluhareff informed company founder Igor Sikorsky that its sharp sweep would delay the onset of transonic compressibility, noting "The general shape and form of the aircraft is, therefore, outstandingly adapted for extremely high speeds"

Sikorsky called this the "Dart fighter", and Hallion cites 1942 windtunnel tests done on models. DonPMitchell (talk) 02:23, 1 April 2014 (UTC)

Delta Wing Work at Langley and Aberdeen
I've checked some of the key sources that Hallion and Neufeld cite, which can be found on the NASA Tech Report Server. Namely, von Karman's report to Hap Arnold. Also Robert T. Jones collected works are there, including his papers on swept and delta wings. From this, we can piece together a brief chronology:

1944 Aug 19. Griswold meets with Jones at Langley to discuss a subsonic deltawing glide bomb. Jones does some theoretical work but decided it is uninteresting.

1945 Jan. Jones says in his memoirs that he realized sweepback is a critical idea for supersonic flight, keeping wing inside Mach cone.

1945 Feb 27. Jones presents result to Jean Roche, Air Force liason officer at Langley. See photo of his drawings and Roche's dated signature in both of Hallion's papers.

1945 Apr. By now, Langley is doing windtunnel tests and NACA officials are aware of Jones' work. In April, von Karman does his own supersonic wind tunnel tests at Aberdeen

1945 May 1. Von Karman leads his Air Force Scientific Advisory Board's trip to Europe to inspect German laboratories. He interviews Lippisch on May 23.

1945 Aug. Von Karman's report to Hap Arnold, "Where We Stand". This report discusses importance of sweepback, includes photos from his April wind tunnel tests and cites Jones and then discusses what the Germans had done. He recommends that the Air Force build a supersonic prototype with an engine and perform supersonic flights with it. This is the month that the Air Force asks Convair to propose a supersonic prototype. All of this information (Lippisch, Jones, von Karman's) would have been transmitted to Convair during this period.

1946 Feb. Lippisch arrives in USA, DM-1 was completed in Germany and it arrives at Langley this months for wind tunnel tests.

This demonstrates that the Lippisch' work _confirmed_ von Karman and Jones' work on delta wings, but it did not _inspire_ it. It was not a surprise discovery they made in Germany. Convair's initial design was a swept wing, later replaced with delta. The key idea is sweep angle inside Mach cone. This idea of sweepback was almost certainly communicated to Convair by the Air Force SAB. DonPMitchell (talk) 17:21, 1 April 2014 (UTC)


 * I don't see how any of this addresses the issue at hand. The issue is not "who invented the delta" or "who noticed sweep back's effect on transonic performance", the question is and always has been "who's work was used to select the delta for the F-92?" Do you believe anything in the above post offers an alternate reading of this? I simply don't see it. Perhaps you can connect the dots for me. Maury Markowitz (talk) 18:37, 1 April 2014 (UTC)


 * The Air Force Scientific Advisory Board (von Karman et al) knew about swept wings. The German work confirmed the theory.  They proposed the construction of the swept wing supersonic prototype.  The point is, it was not a new idea for them when they saw Lippisch's work.  It just became more of a certainty when they realized the Germans were using it. DonPMitchell (talk) 19:15, 1 April 2014 (UTC)


 * In particular, the evidence does not indiate that von Karman went to Germany, saw Lippisch's work and decided "We have to build one of these!". We know that he already knew about this, he him self was doing wind tunnel tests, he knew about Jones' work.  SO I think we must conclude that all of this information informed his decision.  Also note that Convair never built a copy of the DM-1, their design never really looked like that, it has thin wings like the test models Langley was playing with.  I think we must say that the decision to build this type of supersonic prototype was informed by the work of JOnes, von Karman and Lippisch.  DonPMitchell (talk) 19:30, 1 April 2014 (UTC)

Von Karman's report: Collected workd of R.T. Jones:


 * Note that in Jones' May 11 1945 report, the wing he is illustrating is a delta.

SO I think we must conclude that all of this information informed his decision No no no! This is precisely what we cannot do. Not "we don't have enough information to conclude this" or "the evidence doesn't suggest this". Literally, the wiki rules state very clearly that this is a violation of policy. Either you provide a credible source that states exactly that, or it doesn't go in the article. Maury Markowitz (talk) 01:47, 10 April 2014 (UTC)
 * The relevant policy being WP:SYNTH, I believe. - The Bushranger One ping only 02:24, 10 April 2014 (UTC)

Evidence for non Lippisch origin of Convair Delta Wing
Continuing our discussion, The theory that the XP-92 is based on the DM-1 is unsupported by references. There is a misunderstanding of the technical content of the NACA report that is referenced in the article. It is not a study of the DM-1's transonic behavior, it is an analysis of its behavior at not greater than 45 mph, due to the structural weakness of the glider. It is not credible to assume that this plywood glider was the basis for the design of a supersonic fighter aircraft. Finally, the references to respected historian Dr. Richard P. Hallion is arbitrarily rejected, calling him a "jingoist" for contradicting a strictly German-origin theory.

Let's look at some references.

First we have the reports by Von Karman who led the investigation of the German aviation laboratories in May of 1945. He states clearly that the dramatic discovery was the supersonic wind tunnel experiments done at a secret laboratory in Braunschweig, on swept-back wings, delta wings with "small thickness ratio" (he refers to the Herman Goering Luftfahrtforschungsanstalt, which had Germany's largest supersonic wind tunnel). He also explicitly states that his group was aware of the work of R.T. Jones at Langley, but that the work at Braunschweig confirmed it. In his report to the Air Force, he discusses supersonic test data from Braunschweig, Kochel, Goettingen, Aachen and Munich. The only mention of Lippisch is in regard to the Messerschmitt-163. The Flight International magazine says (without any citation) the documents shipped back to the Air Force was primarily Lippisch's research, but Von Karman's book and report contradict that and emphasizes the Braunschweig wind tunnel data.


 * 1. Von Karman, Theodore, Aerodynamics: Selected topics in the light of their historical developments, Cornell, 1957.
 * 2. Von Karman, Theodore, Where We Stand: A Report Prepared for the AAF Scientific Advisory Group, August, 1945.

Next, we have the statements of Adolph Burstein, the XP-92 project engineer and of Bill Chana, a test engineer. They proposed a 35 degree swept wing in November 1945 (recall, the DM-1 was not tested at Langley until Feb 1946). Supersonic wind tunnel tests (May 17-July 26 1946) of models were unsatisfactory and they increased the angle of sweep to 45 and then 60 degrees and then, in their words, "filled in" the wing to form a triangle wing. The triangle wing is mentioned in reports dating July 5, and by July 26, in a Convair research report, he says they converged on a 60 degree triangle wing. On one of their trips to Wright Field in "late July", they met with Lippisch and other Germans. They were encouraged by their discussions about wing design, but Burstein states they disagreed with Lippisch' thick-wing design.

All of these sources claim that Burstein and Shick were unaware of Lippisch's work when they peformed their wing tests and design evolution.
 * 3. Bradley, Robert E., Convair Advanced Designs II, Crecy, 2013. (Researcher at the SDASM, location of the Convair archives)
 * 4. Bradley, Robert E., “The Birth of the Delta Wing”, J. Am. Aviation Hist. Soc., Winter 2003
 * 5. Hallion, Richard P., "Convair's Delta Alpha", Air Enthusiast Quarterly, June, 1976.
 * 6. Hallion, Richard P., “Sweep and Swing: Reshaping the Wing of the Jet and Rocket Age”, NASA’s Contributions to Aeronautics: Volume 1, NASA, 2010. (quotes Burstein)
 * 7. Smith, Dale, "Speed Freak", Air & Space Magazine, January 2006. (quotes Bill Chana).
 * 8. Wegg, John, General Dynamics Aircraft and Their Predecessors, Putnam, London, 1990.

Where did Convair get the November 1945 idea of the thin swept wing? This is unknown. There is firm evidence that Jones' delta-wing thery was a widely known controversy before the discoveries in Germany. Von Karman states that Boeing's chief engineer (Schaier), who was part of his SAG team in Germany, knew about Jone's work, and Schaier states unequivacably "I give him [Jones] full credit for the B-47 swept wings". But it must be admitted there is no such direct evidence that Convair's design was informed by Jones. It is only very weakly implied by Hallion, which is not sufficient evidence. It is also possible Convair's design was informed by the Braunschweig wind-tunnel experiments on "small thickness ratio" wings, mentioned by Von Karman. Again, unsupported. However, there is even less evidence or credibility to the idea that Convair's thin swept wing was based on Lippisch's thick delta wing.

Nor should wikipedia claim in this article or the DM-1 article that an unflown plywood glider was the template for the XP-92 and other supersonic delta wing fighters. This appears to be a popular trope in blogs, forums and magazine articles, but not supported by original sources. Some sources claim (carelessly I believe) that Convair first met with Lippisch and then subsequently designed a delta wing, but this contradicts the original interviews with the engineers and the Convair weekly reports in the archives at SDASM (as described by Bradley). DonPMitchell (talk) 07:09, 14 April 2014 (UTC)


 * As always, feel free to post the references in question. I mean the actual text, so I can read it. Maury Markowitz (talk) 10:38, 1 May 2014 (UTC)
 * And also remember that while primary sources can be used, intrepreting primary sources, especially in a manner that contadicts secondary sources, is Original Research, even if the secondary sources are wrong. Verifiability, not truth. - The Bushranger One ping only 10:43, 1 May 2014 (UTC)


 * Editing rules are not a substitute for doing scholarly research or having a sound technical knowledge of a subject. In any case, you win.  The article will say whatever you want it to say.  DonPMitchell (talk) 18:21, 2 May 2014 (UTC)

M.52
The early XP-92 concept looked a lot like the M.52, although the propulsion system was quite different. However, this design concept, of a cabin within a ducted jet propulsion unit, was well known long before either plane. Flight International in 1941 Aug 28 attributes it to S. Campini, and you can see it clearly diagrammed in Campini's 1935 US patent 2,024,274.

There's a bit too much amateur speculation in this article about this plane looks like that plane; for example, the XP-92 is not derived from the DM-1, and the citations of that part of the article make no such claim. DonPMitchell (talk) 03:13, 25 September 2015 (UTC)

What is a "radiator engine"?
Can anyone explain, what is a "radiator engine"? That is mentioned in the paragraph titled "Early work", where it is stated, "...Years earlier, the company had performed designs which involved liquid-cooled radiator engines..."

I can find no information about "radiator engines". Is this a typo? Perhaps the correct wording is, "... liquid-cooled radial engines..."? 216.1.180.162 (talk) 21:32, 26 July 2017 (UTC)


 * Actually, it's "liquid-cooled engine radiator ducts". Whoever paraphrased that, or a subsequent editor, lost the sense of what the source was discussing. I'll try to make some clarifications to the text soon. - BilCat (talk) 21:44, 26 July 2017 (UTC)


 * I've removed the sentence, as it's an unnecessary digression from the main point, which is the XF-92. - BilCat (talk) 21:56, 26 July 2017 (UTC)

Hallion revisited
Richard P. Hallion; "Lippisch, Gluhareff, and Jones: The Emergence of the Delta Planform and Origins of the Sweptwing in the United States", Aerospace Historian, Vol.26, No.1, Spring/March 1979. pp.1-10. (if you have access to jstor you can find it there)

This study provides a great deal of backup information supporting Hallion's thesis, that Lippisch had next to no influence on US delta wings. Briefly, Michael Gluhareff was a Russian emigree to the US, where he invented a delta wing in the 1930s and saw its potential for high-speed flight. Come WWII he approached Roger W Griswold, who in due course used it on a proposed glide bomb which he showed to Robert T Jones at Langley. Jones discovered the principle of sweeping-back steeper than the shock cone to maintain subsonic aerodynamics and avoid shock/trim issues and presented his work in the spring of 1945, before Lippisch had even arrived in the US. The failure of the DM-10's thick wing left Lippisch's influence dead in the water.

Jones then applied the principle to the swept wing and it was this which Convair picked up on. But their wing was lousy and they found that thay could improve it markedly by straightening out the trailing edge and sweeping the leading edge even more. Thus, Jones indirectly influenced Convair's independent discovery of the high-speed delta. Convair engineer Ralph Schtick later went to see Lippisch and "they mutually exchanged wind tunnel data". Schtick later commented that Lippisch's work brought them moral support but "We did not go along with many of his ideas, such as a very thick airfoil."

Approx. 20% of Hallion's text is his bibliography.

Hope this helps clarify a few things. &mdash; Cheers, Steelpillow (Talk) 20:27, 27 September 2020 (UTC)