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“Invisible” Aircraft (Stealth: The Early Years)

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Wingknut

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Hi folks,
Hope this isn't all old news, but after Bill Gunston's 'Back to Balloons and Gliders?' ('Air International', May 1986, Vol. 30, No. 5, pp. 228-9), here are references to (alleged) early 'stealths' (reduced optical/radar signature):

1) Professor S. G. Kozlov's 'Nyevidimyi Samolyet', ("Invisible aeroplane"), aka the 'PS', ("Prozrachnyi samolyet" – "transparent aircraft"?). A Yakovlev AIR-4 apparently had its opaque parts painted white and/or covered with a mirror-like amalgam or enamel. Structure then covered with transparent "rodoid", (a French substance like tough cellophane or "organic glass"). Rodoid apparently effective but opaque structure hard to conceal. Project cancelled in 1935. See also:
i) Article at: http://www.aviation.ru/okb.php.
ii) 'Krylja Rodiny' (N12 2001) article "AIR-4 - the Transparent Biplane by Sergei Kozlov", http://www.aviapress.com/viewonekit.htm?KRR-200112
iii) Posting by 'Arthur', Stealth Aircraft thread, at:
http://forum.keypublishing.co.uk/archive/index.php?t-12018.html
iv) More links at: http://www.military.cz/accessories/Invisibility.htm, and:
http://www.prz.edu.pl/~awionika/dyd/Seminar_C2/Grzegorz%20Lenart.pdf.
The only AIR-4 image I know apparently comes from 1930 and shows Alexandr Yakovlev himself standing in front of a (thoroughly opaque) AIR-4:
http://www.forcollector.com/big/item_1980.jpg.

2) 'Air International' (c. 1986) on Imperial German transparent aircraft-coverings. Cf. "In the early 1900’s Germany experimented with a clear cellulose skin called Emaillit. This skin, along with silver painted internal structures, made the aircraft effectively invisible from the ground when it was over an altitude of 900 ft", David Hall, David Andrews & Sangeon Chun, 'Stealth: 15 More Minutes …', http://www.aoe.vt.edu/~mason/Mason_f/StealthS03.pdf.
Hall (et al) cite J. Jones, 'Stealth Technology: The Art of Black Magic', (AERO, Blue Ridge Summit, PA 1989), see thread ('Art of Black Magic') at: http://www.secretprojects.co.uk/forum/index.php/topic,2782.0/highlight,stealth.html.

3) Alleged 'stealth' Horten Ho-229 / Gotha Go-229:
"The world's first stealth fighter flew on February 14, 1945..... The Hortens had a long distinguished history of building advanced flying wings and the Ho-IX/Go-229 had a largely wood fuselage that contained a mix of sawdust, charcoal, and resin to absorb radar. Its own flying wing configuration would help too but to make sure the Germans developed a radar-absorbing paint called "Schornsteinfeger" (Chimneysweep) that was a thick carbon laden mixture that eventually became the basis of the US "Ironball" paint idea for the U-2", http://greyfalcon.us/US%20Saucers.htm.
Cf. "The skin was very thick: 17 mm, all plywood; three times the necessary strength. On the production aircraft, this would be replaced by two 1.5 mm plywood sheets, with a 12 mm layer of sawdust, charcoal and glue mix, sandwiched in between. The charcoal in this much lighter skin would diffuse radar beams, and make the aircraft "invisible" on radar", http://www.greyfalcon.us/The%20Horten%20Ho%20229.htm.
Based on other Greyfalcon stuff, I’m 95% sure this is just more "Projekt Saucer" dreck, but (just to check) could there be anything in these claims? (Reducing aircraft radar cross-section was discussed by Watson Watt c. 1936. See Gunston, p. 228.)

4) I know this project is post-war but see also the "The first stealth aircraft" thread on the reduced radar-cross-section Boulton Paul Balliol:
http://www.secretprojects.co.uk/forum/index.php/topic,882.0/highlight,balliol.html.
Can anybody think of other early optical and/or radar signature reduction measures?
Cheers,

'Wingknut'.
 

Justo Miranda

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Please see attached some text from "Reichdreams Databook 2002"
 

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Justo Miranda

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Please see attached two pics of german WWI "Stealth"
 

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Wingknut

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Excellent images and text, Justo. Good to see a "transparent" WW1 German bomber again.
I'm afraid I'm still sceptical about German scientists tackling RCS-reduction during WW2, (as I am about many a claim from Greyfalcon). Pardon my asking but are there any well-authenticated, independent references to these projects? I'm reminded of a British tv. news-item in 1986 about the first glimpses of the B-2 which described the Northrop XB-35/YB-49 series as stealth designs on the strength of their flying wing layout, when clearly these planes had some way to go in terms of utilising radar-defeating materials. (Letting aside the very radar-friendly props. of the XB-35.)
Thanks as ever.
 

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Wingknut said:
Pardon my asking but are there any well-authenticated, independent references to these projects?


Here

http://www.bbc.co.uk/dna/h2g2/brunel/A591545

http://en.wikipedia.org/wiki/Radar_absorbent_material

http://www.radarworld.org/radarwar.pdf

http://www.uboat.net/forums/read.php?20,58738,58742,quote=1

http://www.uboataces.com/sonar-coating.shtml

http://en.wikipedia.org/wiki/Horten_Ho_229

http://www.nurflugel.com/Nurflugel/nurflugel.html

http://www.nurflugel.com/Nurflugel/Lippisch_Nurflugels/p-11/body_p-11.html

http://www.luft46.com/lippisch/lip11.html

http://uboat.net/technical/detectors.htm

http://www.uboataces.com/radar-decoys.shtml

http://www.navweaps.com/Weapons/WNGER_86mm_AA_Rocket.htm
 
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Wingknut

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I appreciate the links, Justo, although the bulk of them seem to be about submarine-snorkels and not about aircraft, and some of the ones that are about aircraft (or missiles) seemingly don't mention radar at all.
I already knew that some thought had been given to making U-Boat snorkels less detectable, but my claim is (and remains I'm afraid) that there doesn't seem to be much reliable data about radar-defeating measures for Nazi-era German aircraft. Two worries:
i) There seems to be a certain amount of circular citation going on - lots of things seem to loop back to things like the (less-than-ideally reliable) Greyfalcon. Hence my comparing "Nazi stealth" claims to "Projekt Saucer" claims - circular citations being a common feature to both.
ii) Despite the plethora of sources for rcs-reduction on snorkels, there seems to be a distinct shortage of pre-1980's material on rcs-reduced German WW2 aircraft. In other words, sources seem to have arisen which started attributing rcs-reduction to WW2 Germany once rcs-reduction techniques were already being widely discussed. (And no, I don't think the reason for this was a sudden rush of declassified documents c. 1988.)
If Bill Gunston had bought it, I'd buy it but for now, I remain sceptical.
Thanks as ever,

'Wingknut'
 

overscan (PaulMM)

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Bill Sweetman makes this claim about Horten intentions to use radar absorbent materials in "Stealth Bomber", Airlife, 1989.
 
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Wingknut

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Thanks.
Is there any source that we can be referred to from (say) pre-1988, i.e. one that pre-dates the explosion of stealth articles and speculations from c. 1985 onward (much of it bungful of disinformation and speculation)?
I'm talking about contemporary records or early postwar references, not fleeting references made 40+ years after the facts attested to and (more to the point) after stealth principles were already well-embedded in the zeitgeist.
Yous aye, still a little bit sceptical,
'Wingknut'.
 

Justo Miranda

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Here the British side
 

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Wingknut

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Thanks but I fear the search for an authoritative pre-1985 source for "Nazi Stealth" goes on. I could refer us all to another half-dozen websites which roundly reject the idea of stealth technology being available to be applied to Gotha Go 229's, (or any other Nazi-era aircraft). I still think the stealth Go 229 is best explained as a post-facto anachronism based on the aerodynamic resemblance between the Go 229 and later stealth aircraft. (The vast majority of joint references to stealth and the Go 229 simply point out the aerodynamic similarities between the Go 229's planform and that of the B-2.)
I appreciate all the posts very much but until someone finds a pre-1985 detailed reference to a Gotha (or similar) Stealth, I remain unconvinced.
However, optical "stealth" is interesting, and it seems that that one was genuine, (cf. the Kozlov-adapted AIR-4).
Likewise, noise-reduction proposals - I recall reading years ago about a proposal for adapting Airspeed Horsa gliders so they could each carry an 8,000 pound bombload and serve as (practically) silent low-level bombers. (Acoustic stealth?)
This next is almost an anti-stealth project but I read (in 'Airfix Magazine') years ago about an experiment in painting misleading geometrical figures on British WW1 aircraft so that that they would appear to be pointing in directions at variance with their true alignment.
Any one know any more about any of those?
Cheers,
'Wingknut'.
 

Justo Miranda

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Classified USAF stuff ?

The XP-61C program lead to a scandal and the first substantive break between Northrop and the USAF. Jack Northrop was obsessed with flying wing aircraft and, in particular, with promoting his XB-35 flying wing bomber as a replacement for the B-36. He was responsible for diverting much effort away from the XP-61C into the XB-35 program, seriously delaying the former. This eventually resulted in an explosive meeting during which Northrop was instructed to cease all work on the XB-35 and concentrate on the XP-61C. Northrop responded by threatening to “go public” on the XB-35 vs B-36 debate, alleging that the selection of the B-36 was the result of a corrupt conspiracy against his company. This would, of course, have compromised the secrecy that surrounded B-36 development. USAF action was swift and decisive. Northrop was told to continue with the XB-35 (the Air Force being determined that it would never proceed beyond a single prototype but the XP-61C program was taken away from Northrop and assigned to Goodyear, which had been a subcontractor for production of Black Widow components





The P-61 was heavily involved in the Thunderstorm Project (1946–1949) that was a landmark program dedicated to gathering data on thunderstorm activity. The Thunderstorm Project was a cooperative undertaking on the part of four U.S. government agencies: the U.S. Weather Bureau, the U.S. Army Air Force, Navy and National Advisory Committee for Aeronautics (later to become NASA). Scientists from several universities also participated in the initiation, design and conduct of the project. The Florida phase of the Thunderstorm in 1946 continued in a second phase of the project carried out in Ohio during the summer, 1947. Results derived from this pioneering field study in 1946–47 formed the basis of the scientific understanding of thunderstorms and much of what was learned has been changed little by subsequent observations and theories. Data was collected for the first time from systematic radar and aircraft penetration of thunderstorms forming the basis of many published studies that are still frequently referenced by mesoscale and thunderstorm researchers.
The last USAF F/RF-61C finally left USAF service in 1952.

















In November 1949, the Air Force ordered all XB-35s scrapped. Scrapping of the XB-35s began in
January 1950, the only flying YB-49 was destroyed on March 1950 during a failure of the nose landing
gear. See the Northrop and Symington article for more details.

Northrop asked to meet with NASA officials in early 1979 to explain his ideas about the design--and to tell why his version was killed 30 years earlier.
"It was a fascinating story," said Gerald Kayten, deputy director of NASA's aeronautical systems divisions, who attended the half-day meeting at Northrop University in Inglewood. "But there really wasn't much of a meeting of minds. All Mr. Northrop seemed to be interested in was pointing out that his airplane was a pretty good airplane. He didn't need to convince Us, because we already agreed with him." NASA already decided, however, to put the Flying Wing design "on a back burner" because it was best suited for much larger cargo planes than will be needed by military or commercial users for the next two decades, Kayten told The Times.
Northrop Claims AF Scuttled 'Flying Wing'
by Ken Gepfert, Los Angeles Times, December 8, 1980
In the years during and immediately after World War II, aviation pioneer John K. Northrop developed and tested an odd-looking, jet-propelled bomber that he believed would revolutionize aircraft design. With no fuselage and no tail, the craft was aptly dubbed the "Flying Wing," and the Air Force selected it to replace the war-tested B-29.
Then, in 1949, Flying Wing production was abruptly canceled and all test planes were ordered destroyed.
For three decades, Northrop has refused to discuss why this promising airplane--the culmination of his lifelong dream -- was scrapped so suddenly.
But in a dramatic taped interview broadcast last week, the 85-year-old Northrop Corp. founder finally told his secret The Flying Wing was canceled, he said, because he refused to obey an Air Force order that he merge his then-fledgling company with a more established competitive firm. When he balked, Northrop said, the Air Force summarily awarded the bomber contract to the competing firm.
Northrop said he kept quiet for all these years because he feared the Pentagon would blackball his company if he disclosed the story. He said he even committed perjury before Congress to hide the facts.
Northrop's allegation shed new light on a generation-old controversy that has become one of the biggest mysteries in American aviation. But it also raised new questions that may never be answered.
In a precise unemotional tone, Northrop told his story to longtime aerospace reporter Clete Roberts in an interview on Los Angeles Public Television station KCET. Since that interview, taped in October, 1979, Northrop has suffered a series of strokes that have left him seriously ill and unable to speak.
The 14-month delay between the interview and its broadcast as part of the KCET documentary last week was due partly to delays in gathering additional material for the telecast and partly to a postponement request by Northrop.
Northrop's story was corroborated by Richard W. Millar, 81, who witnessed the drama as chairman of the Hawthorne-based aerospace company at the time and who still serves as Northrop vice chairman. But Millar, also interviewed by Roberts, has refused to respond to other questions since the broadcast, saying only that his taped statements "provide an accurate account" of the Flying Wing cancellation.
The Air Force secretary accused of issuing the merger order, former Sen. Stuart Symington (D-Mo.), 79; refused to be interviewed by Roberts. Repeated attempts by The Times to reach both the elder Symington and his son, also a former congressman, were unsuccessful. Most of the other witnesses to events surrounding the Flying Wing cancellation are dead.
Based on the KCET broadcast and subsequent interviews by The Times with Northrop's son and others familiar with the story, however, the picture emerges of a man in a 30-year struggle between his love for the company that bears his name, and for the aircraft that was to be his contribution to aeronautical history.
Northrop, who has long felt his plane had been wronged by history, finally decided to tell his story after becoming convinced--incorrectly as it turned out--that the National Aeronautics & Space Administration was about to resurrect his basic idea.
The Flying Wing bomber was the product of more than 20 years of experimentation by Northrop, who believed as early as 1929 that a plane that was all wing would out-perform traditional designs featuring wings fuselage and tail assembly. By putting the 15-man crew eight engines and the bomb bay inside the wing, Northrop minimized the plane's drag and maximized its lift. As a result. the Flying Wing would carry a payload that was nearly equivalent to the plane's weight--a feat matched by no previous aircraft.
Wins Competition
To select a bomber to succeed World War II's B-29s, the Air Force pitted Northrop's Flying Wing, designated the B-35 and later the B-49, against a traditionally configured bomber built by Consolidated Vultee Aircraft Corp. (Convair), which later became a division of General Dynamics Corp. The Flying Wing won a competition against Convair's B-36 in 1948 and the Air Force awarded Northrop a contract to build 35 bombers with the possibility of ultimately producing 200 to 300 planes.
But Northrop's elation turned into disbelief when he and company chairman Millar were summoned to meet Symington shortly after winning the contract in June 1948, according to their taped statements.
Noting that his was "a very strange story and perhaps difficult to believe," Northrop told KCET reporter Roberts that Symington launched into a "lengthy diatribe" about how the Air Force did not want to sponsor any new aircraft companies because the Pentagon could not afford to support them with continuing business on declining post-war budgets. Then, Northrop said, Symington demanded that Northrop Corp. merge with Convair.
General Reacts
At that point, Northrop recalled, Brig. Gen. Joseph T. McNarney, commander of the Air Materiel Command and subsequently president of Convair said, "Oh, Mr. Secretary, you don't mean that the way it sounds."
"You're . . .right I do," Symington answered, according to Northrop and Millar.
Northrop and Millar told KCET's Roberts that they then visited Floyd Odium, head of Atlas Corp., which controlled Convair, to discuss a possible merger. But talks soon ended, Northrop said, because Odlum's demands were "grossly unfair to Northrop "
A few days later, Northrop recalled, Symington telephoned him and said, "I am canceling all of your Flying Wing aircraft."
"I said, 'Oh, Mr. Secretary, why?' "
"He said, I've had an adverse report,' and hung up," Northrop recounted. "And that was the last time I talked to him and the last time we could reach him by phone or any other way."
As part of the cancellation, Millar added, the Air Force ordered the destruction of seven Flying Wings then under construction. "Those airplanes were destroyed in front of the employees and everybody who had their heart and soul in it'" said Millar, his voice cracking.
After the Air Force canceled the Flying Wing and awarded the contract to the competing Convair B-36, a House Armed Services subcommittee held hearings in 1949 to investigate allegations that the Pentagon~used coercion in its aircraft procurement practices.
Prompted by Rumors
According to press accounts at the time, the investigation was prompted by "ugly rumors" about Symington and other Pentagon officials. One rumor investigated--and denied by witnesses at the hearing--was that Symington had been considered to head the firm that would result from the proposed merger between Consolidated Vultee and Northrop.
Among the witnesses who denied seeing any evidence of Pentagon coercion was John K. Northrop.
Northrop testified that he did not "feel there was any unjustifiable or unreasonable pressure in the cancellation of the B-49 contract. I would call the move reasonable and logical." When asked under oath if he was in fear of Pentagon reprisal, Northrop laughed and said, "I have no fear of reprisal."
Thirty-one years later, when asked about his testimony by reporter Roberts, Northrop responded, "My reaction is that under pressure of the life or death of Northrop Corp., I committed one of the finest jobs of perjury that I've ever heard."
Northrop said in the taped interview that he did not tell the full story until now because he feared that Symington would cause the "complete obliteration" of his company. Millar said that the meeting with Symington was so "brutal and bare-faced" that "you almost had to assume that he would be prepared to take further steps if we didn't do as good boys and go along."
After serving as Air Force Secretary, Symington was elected to the U.S. Senate, where he remained for 24 years. He was an influential member of both the Armed Services and Foreign Relations committees, and unsuccessfully ran for the Democratic presidential nomination in 1960. He retired from the Senate in 1977.
Through his secretary in Washington, Symington told reporter Roberts that he "never did (the) sort of thing" alleged by Northrop and Millar.
Prior to Northrop's account, a popular explanation for the Flying Wing's demise was technical failures. The aircraft did exhibit stability and control problems during testing, and one test plane disintegrated during a rout~ne night in 1948, killing all five crew members.
The Air Force was apparently convinced enough that problems were being corrected to award the production contract to Northrop just five days after the accident. however. The accident investigation proved inconclusive.
Because of Symington's refusal to answer questions and the death of such key witnesses as Gen. McNarney, Convair chief Odlum, and post-war Defense Secretary Louis Johnson, there may never be consensus on the fate of the Flying Wing.
Whatever the reasons, there is no question Northrop personally was devastated by the cancellation and destruction of the Flying Wing--his lifelong obsession.
In 1952, at the relatively early age of 57, Northrop abruptly retired and divested himself of all interest in the company he founded. "At that time, Jack essentially felt his career was over," said historian William A. Schoneberger, who is writing a book on Northrop's life.
According to his son, John H. Northrop of La Canada Northrop was particularly troubled by persistent historical accounts that portrayed the Flying Wing as a technical failure in light of its cancellation by the Air Force. The younger Northrop told The Times his father decided he could no longer remain silent. After reading that NASA was considering a Flying Wing design for an advanced, fuel-efficient cargo plane.
Northrop asked to meet with NASA officials in early 1979 to explain his ideas about the design--and to tell why his version was killed 30 years earlier.
"It was a fascinating story," said Gerald Kayten, deputy director of NASA's aeronautical systems divisions, who attended the half-day meeting at Northrop University in Inglewood. "But there really wasn't much of a meeting of minds. All Mr. Northrop seemed to be interested in was pointing out that his airplane was a pretty good airplane. He didn't need to convince Us, because we already agreed with him." NASA already decided, however, to put the Flying Wing design "on a back burner" because it was best suited for much larger cargo planes than will be needed by military or commercial users for the next two decades, Kayten told The Times.
Nonetheless, id a letter sent to Northrop after the meeting, NASA Administrator Robert A. Frosch acknowledged Northrop's pioneering work and said "our analyses confirmed your much earlier conviction as to the load-carrying and efficiency advantages of this design approach."
Armed with this evidence that the wisdom of his approach finally was being recognized by the government, Northrop asked the company's present management for permission to tell his story, according to Northrop's son.
Even after telling his story to Roberts, Northrop had second thoughts and asked the reporter to delay broadcasting the interview for several months, according to the KCET reporter. "Then one day he called and said 'Go ahead, Clete. It's all clear now,' " Roberts recalled.
Northrop, now seriously ill in a Glendale hospital, was given a private screening of the documentary before it was broadcast. He could not speak to give his reaction, his son said, but "he put his hands together and shook them, like a fighter does, to show us he was pleased."
 

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Justo Miranda

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Classified USAF stuff ? (post-2)

http://www.project1947.com/fig/1948air.htm
 

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Optical stealth samples
 

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Wingknut

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Justo, once more I am left speechless at the range and quality of the data you post on this site. I don't how you do it but I am continually delighted that you do. We're all in your debt.

Many, many thanks.

'Wingknut'.
 

Antonio

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I agree with you Wingknut ;)
 

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Wingknut said:
Justo, once more I am left speechless at the range and quality of the data you post on this site. I don't how you do it but I am continually delighted that you do. We're all in your debt.

Many, many thanks.

'Wingknut'.

I agree with Wingknut mind at 110%.
Thanks again Justo for all these gifts.....
 

Justo Miranda

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Thank you
Actually ,the forum is an extremely useful professional tool that allows me to gauge the level of acceptance of each project and improve my future publications
My contribution tries to pay for that...
 
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Wingknut

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Small pendant to something I said above about 'anti-stealth': I lost this source years ago (Airfix Magazine c. 1982?) but I read an article (illustrated with diagrams and photographs) about a British WW1 experiment in painting aircraft with deliberately high-visibility but misleading geometrical designs. (Skewed-perspective box-grids, diminishing overlapping rectangles, etc.) The idea was not to make the plane hard to see but hard to shoot at - enemy pilots would be presented with conflicting sets of clues as to which way their target was heading, and so be put off their aim. (Well, that was the theory anyway ...) I think a Bristol Monoplane and (possibly) a Sopwith Pup were among the subjects.
I think I read these experiments were shaped by advice from painters of the Vorticist school (Britain's short-lived version of Futurism), like Wyndham Lewis. The overall effect was very like that of the Brewster F2A-1 colour-scheme Justo so kindly posted. Not so much like stealth and more like M.C. Escher drawings in the sky. As far as I know, no one has proposed making the actual structure of aircraft deliberately peculiar-looking with a view to distracting enemy fire ... although it might explain some of Richard Vogt's more inspired moments.
All best, as ever.
 

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"..painting aircraft with deliberately high-visibility but misleading geometrical designs.."

"Dazzle paint" it was called in the navy and according to what I've read about it, it was relatively
succesful, although it probably was hard to determine, if a torpedo missed a ship because of
this paint work, or due to other factors.
 

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Zebras achieve good results with optical distortion
Post-1
 

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Zebras achieve good results with optical distortion
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Wingknut

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Excellent images, as ever.

Found a couple more references to optical 'stealth' (old and new):

1. I started this thread considering transparent aircraft as pre-WW2 'stealths'. But where Rodoid and Emailit aircraft used passive vision-defeaters, Yehudi and Compass Ghost seem like genuine optical stealth – active visual-detection countermeasures that cut detection-range dramatically so the target will only register the approaching aircraft after the aircraft has deployed its weapons or it's otherwise too late to take evasive action. See also the account of British and American interest in an airborne version of "Professor Burr's diffused lighting system", Musee Naval De Quebec, http://www.mnq-nmq.org/english/vivez/impacts/camoufla.htm.

2. I like the idea of Yehudi lights being varied in intensity to match the changing sky - that kind of environment-responsiveness seems harder to achieve with radar, where the illumination is local and artificial. (Although truly environment-sensitive colouring is presumably a long way off at best and would face the problem that faces traditional camouflage, namely that deceiving observers with different viewpoints can call for radically different colour-profiles.) But see 'Innovations in Electro-Optical Camouflage: PROJECT CHAMELEO' (http://www.chameleo.net/InnEOCam-PC-Final.ppt), although the fact that Project Chameleo's list of inspirations includes 'The Philadelphia Experiment' and 'The Invisible Man' doesn't inspire confidence.

3. A 2006 patent, 'Methods and Apparatus for Camouflaging Objects', (US Patent 7132635) can be found at: <http://www.patentstorm.us/patents/7132635-fulltext.html>.

4. Any references I've found so far to 'Vorticist' disruption / razzle dazzle paint are a) all post-WW1 and b) refer exclusively to ships. However, I've found one image of a De Havilland DH-9 in dazzle-patterns, (see http://www.earlyaviator.com/archive1.htm).
Cheers,

'Wingknut'
 
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Wingknut

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Quick follow-up re: the proposed bomber version of the Airspeed Horsa glider:
"Projected AS.52 to specification X.3/41 designed (but not built) to carry up to 8,000 lbs (3,632 kg) of bombs. Powered version with two 375 hp Cheetah Xs also projected, along with AS.53 vehicle-carrying glider."
http://www.jaapteeuwen.com/ww2aircraft/html%20pages/airspeed%20as51%20horsa.htm
(Very similar text at: http://www.fiddlersgreen.net/AC/aircraft/Airspeed-Horsa/info/info.htm)
 

FarSight

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http://pubs.drdc-rddc.gc.ca/inbasket/tfoster.041220_1303.TM%202005-003.pdf

Halpern Anti-Radiation Paint

"During World War II, Germany, concerned with radar camouflage for submarines,
developed “Wesch” material, a carbonyl iron powder loaded rubber sheet about 0.3
inches thick and a resonant frequency at 3 GHz. The front surface of this material was
waffled to produce a larger bandwidth. They also produced the Jaumann Absorber, a
multilayer device of alternating resistive sheets and rigid plastic. This device was
about 3 inches thick with resistances decreasing exponentially from the front to the
back. This device achieved a reduction in the reflectivity of –20 dB over 2-15 GHz.
America, during this period, led by Halpern at MIT Radiation Laboratory developed
materials known as “HARP” for Halpern Anti Radiation Paint. The airborne version,
known as MX-410, had a thickness of 0.025 inches for X-band resonance. The base
dielectric had a high permittivity of 150 due to loading with highly oriented disk
shaped aluminium flakes suspended in a rubber matrix and carbon black for loss. This
material offered a 15-20 dB reduction in reflectivity. Shipborne absorbers were 0.07
inch thick (X-band) iron particle loaded rubber with a permittivity of 20 and enough
permeability to produce resonance broadening.[11,12] At the same time the resonant
Salisbury Screen was developed with about 25% bandwidth at resonance.[13]
Production of Salisbury screens was aided by the US Rubber Company marketing a
resistive cloth called Uskon. Another absorber design that arose at this time was a
long pyramidal structure with the inside coated with Salisbury Screen and the apex in
the direction of propagation. The multiple reflections from the absorber resulted in
high attenuation.[14] The importance of ferrites was known. With the exceptions of the
Jaumann device and the inverted pyramid, these devices are typically narrow band."

Patent by Mr. Otto Halpern:

http://www.google.com/patents?id=hONjAAAAEBAJ&dq=2923934
 
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Wingknut

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Great finds, Farsight – much appreciated. Clearly, there were RCS-reduction projects under consideration in the 1940's after all.
This next is already well-known and not really stealthy as such but there might have been some stealth (plus dispersed sub-munitions) potential in the often-mocked 'bat bomb' plan. This called for the release of incendiary-carrying bats over Japan to roost in vulnerable paper dwellings.
Not much RCS, optical signature or magnetic anomaly generation with bats, plus they're small and fly erratically. (Bit of an auditory signature though, albeit most of it not at frequencies we can hear.)
See (e.g.) C. V. Glines' articles:
1) 'The Bat Bombers', Airforce Magazine, October 1990, Vol. 73, No. 10, online at: http://www.afa.org/magazine/1990/1090bat.html, or:
2) 'Top Secret WWII Bat and Bird Bomber Program', http://www.historynet.com/magazines/aviation_history/3034151.html
Cheers,
'Wingknut'
 

FarSight

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My problem with the text above is the USAAF designation MX-410. According to Designation-systems.net this project had something to do with piston engines and there is no mention of any RAM materials or stealth.

http://www.designation-systems.net/usmilav/mx/1-499.html

"MX-410 --- Allison ------- Piston engines (V-1710-103)"


There are other sites that also mention the MX-410 as some kind of RAM material...

http://www.airpower.maxwell.af.mil/airchronicles/apj/apj91/fal91/cunn.htm

"At the conclusion of World War II, the United States developed RAM that was only marginally effective and very heavy. The added weight of the RAM, known as MX-410, was considered prohibitive, and the substance was never used operationally."
 

moin1900

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Hi everybody

About the german “Invisible” Aircraft of WW1
http://www.koelner-luftfahrt.de/unsichtbarelfz.htm

Many greetings
 
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thehortenlead

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Hey Guys,
Take it from me, someone who has been doing this for over 28 years. Watch the upcoming Nat Geo documentary this fall. It will answer the question. Strait from the experts. I built the full scale verson of the 229 and RCS tested it. I know the answer and everyone will be interested in the findings. We just finished all the tests. Keep poasted and learn more as the info is released by the experts and the Director of the documentary Mike Jorgenson.....

Tk

ps. as to the findings, my lips remain sealed....
 

Orionblamblam

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thehortenlead said:
Hey Guys,
Take it from me, someone who has been doing this for over 28 years. Watch the upcoming Nat Geo documentary this fall. It will answer the question. Strait from the experts. I built the full scale verson of the 229 and RCS tested it.

Can we at least assume that the RCS model was built like the actual 229... internal steel tube construction with wires and connectors all over the place, turbojets, and a plywood skin with the supposed RCS-reducing paint on it?
 

flateric

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http://navylabs.ru/avia/stealth-30/
I.I. Varshavsky's idea of mirror-surface low-viz pattern for aircrafts (various possible implemention platforms were studied, but that was the maximum stage experiment has reached)

http://navylabs.ru/avia/stealth-30/st30-2.php
Segey Kozlov's PS - Prozrachny samolyot (Transparent Airplane) - modified AIR-4 (See photos attached).

Source: Mikhail Orlov, 'Stealth of 30s', Frontline Illustration, Aviaarchive Vol.1
 

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thehortenlead

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Good day,
The question has now been answered ! We, the experts, have built the first full scale model and tested it. We have the results and they are................ You will just have to wait until the documentary. My lips are sealed :) Dont miss it !

Tim AKA "thehortenlead"
 
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joncarrfarrelly

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Orionblamblam said:
thehortenlead said:
Hey Guys,
Take it from me, someone who has been doing this for over 28 years. Watch the upcoming Nat Geo documentary this fall. It will answer the question. Strait from the experts. I built the full scale verson of the 229 and RCS tested it.

Can we at least assume that the RCS model was built like the actual 229... internal steel tube construction with wires and connectors all over the place, turbojets, and a plywood skin with the supposed RCS-reducing paint on it?

Probably not. I hope the doc won't be more of the usual "the Nazi's invented the Modern World stuff."

I wonder if anybody has ever considered putting the Northrop N9M into an RCS chamber. It would be interesting to see the result.
 

AeroFranz

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Not to bash the -229, but I think that the short inlets with direct line of sight to the compressor blades would show up quite nicely on radar (depending on wavelength).
It remains a very elegant design, but I'd be skeptical about its supposed LO.
OTOH, the exhaust is nicely shielded by the trailing edge deck, so it would actually make a fairly decent IR and radar shield when illuminated from below, but I doubt that was even a consideration at the time.
 

Jemiba

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"..but I doubt that was even a consideration at the time" ;)

The Horten brothers began their development of flying wings during the
1920s, about ten years, before the first experiments for detection of aircraft
were made. Maybe the Go/Ho 229 had a quite low RCS, but I severely doubt,
that this was the raison d'être for this design.
Alcohol is good for blood lipids, too, but that's not just the reason for having a beer !
 

Justo Miranda

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I agree
Plese see text at http://www.secretprojects.co.uk/forum/index.php/topic,6069.0.html
 

Michel Van

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this was another idea back in WW2

paint the plane pink !

the idea was that a pink fighter plane in high altitude harder to see

but in dogfight a fighter plane hast to go to low altitude
and then a pink aircraft over green forest is a easy to see target

and there was the problem that some pilot refused to flight in Pink Aircraft
i wonder why ;D

there is a Spitfire PR11 with Pink camouflage
on display in "National Museum of Flight" at East Lothain, Edinburgh, UK
picture here (is under copyright)
http://www.airliners.net/photo/Supermarine-365-Spitfire/1001507/&sid=07cf2c669e3d01a1b45c783f2fc7083a
 

Justo Miranda

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Pink?
 

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