Editing Horten Ho 229 (section)

==Claimed stealth technology==

===Radar absorbent material===
[[File:Horten ho229 laminate.jpg|thumb|Cross-section of the Horten Ho 229 composite wood laminate]]

In 1983, after hearing details of the US stealth system, Reimar Horten advanced a claim that he had intended to add charcoal dust to the wood glue to absorb [[Electromagnetic radiation|electromagnetic waves]] (radar), to shield the aircraft from the British [[Early-warning radar|early-warning ground-based radar]] system known as [[Chain Home]].{{efn|During the war the British also introduced 200MHz radars for early warning of low flying aircraft ([[Chain Home Low]]) and target tracking for ground-controlled interception ([[AMES Type 7]])}}<ref name = "airspace 2016"/><ref name = "natgeo 2009">{{cite web |url = http://channel.nationalgeographic.com/episode/hitler-s-stealth-fighter-3942/Overview24 |archive-url = https://web.archive.org/web/20090627133554/http://channel.nationalgeographic.com/episode/hitler-s-stealth-fighter-3942/Overview24 |archive-date = 27 June 2009 |url-status = dead |title = Flying under the Radar: A History of Stealth Planes |publisher = [[National Geographic]] |date = 2009 |access-date = 6 November 2010}}</ref> This charcoal glue treatment was supposedly planned for the unbuilt production aircraft however, the V3 prototype did not make use of charcoal, and no documentation has been found supporting the claim.<ref name="natgeo 2009"/><ref name=Smithsonian>{{Cite web |title = Is It Stealth? |url = https://airandspace.si.edu/explore/researchers/projects/horten-ho-229-v3-preservation/stealthy |access-date = 24 March 2021 |website = National Air and Space Museum |date = 19 July 2016 |language = en |archive-date = 11 April 2021 |archive-url = https://web.archive.org/web/20210411175211/https://airandspace.si.edu/collections/horten-ho-229-v3/about/is-it-stealth.cfm |url-status = live}}</ref>

[[Northrop Grumman]] engineers conducted electromagnetic tests on the V3's multilayer wood nose cone in 2008. They tested across a frequency range of 12 to 117 THz, with a 10 micron wavelength. The cone was {{cvt|19|mm}} thick and made from thin sheets of [[Wood veneer|veneer]]. The team observed that the "Ho 229 leading edge has the same characteristics as the plywood [of the control sample] except that the frequencies have a slightly shorter bandwidth," which they go on to conclude was likely due to oxidization of the wood.<ref name="arc.aiaa.org">{{cite book |first1 = Thomas |last1 = Dobrenz |first2 = Aldo |last2 = Spadoni |first3 = Michael |last3 = Jorgensen |title = Aviation Archeology of the Horten 229 V3 Aircraft, AIAA 2010-9214 |date = September 2010 |url = https://arc.aiaa.org/doi/10.2514/6.2010-9214 |publisher = American Institute of Aeronautics and Astronautics |doi = 10.2514/6.2010-9214 |isbn = 978-1-62410-159-5 |url-access = subscription}} <!-- cited in https://airandspace.si.edu/collections/horten-ho-229-v3/about/is-it-stealth.cfm --></ref> The team, who assumed the presence of carbon black from visual inspection alone, concluded that the "similarity of the two tests indicates that the design using the carbon black type material produced a poor absorber."<ref name="arc.aiaa.org"/><ref name="Myhra p. 11"/> The Smithsonian Institution then performed a study of the materials used on the prototype, and determined that there is "no evidence of carbon black or charcoal", refuting the hypothesis.<ref name=Smithsonian/>

===Radar cross section and shape===
[[File:Horton 229 V3 - Radar-testing Ho IX V3 reproduction at the San Diego Air and Space Museum (9668114493).jpg|thumb|Radar-testing H.IX V3 reproduction at the San Diego Air and Space Museum]]

A jet-powered flying wing such as the Horten Ho 229 might have a smaller [[radar cross-section]] (RCS) than conventional contemporary twin-engine aircraft because the wings are blended into the fuselage and there are no large propeller disks or vertical and horizontal tail surfaces to provide a typical identifiable radar signature,<ref name="Myhra p. 11">Myhra 2009, p. 11.</ref><ref name = "ng"/> however the front and rear faces of the exposed jet engines do provide a similar degree of reflectivity to propellers.

In early 2008, Northrop Grumman paired television documentary producer [[Michael Jorgensen]] and the [[National Geographic Channel]] to make a documentary to determine whether the Ho 229 was the first "[[Stealth aircraft|stealth]]" aircraft.<ref name="Myhra p. 11"/> Northrop Grumman built a full-size non-flying reproduction of the V3, primarily made of wood, unlike the original aircraft, which had an extensive steel [[Space frame#Aircraft|space-frame]] to which the wooden skin was bolted. After an expenditure of about US$250,000 and 2,500 man-hours, Northrop's Ho 229 reproduction was tested at the company's Radar Cross Section test range at [[Tejon, California]], US where it was placed on a {{cvt|15|m}} pole and exposed to electromagnetic energy sources from various angles from {{cvt|100|m}}, using three [[High frequency|HF]]/[[Very high frequency|VHF]] frequencies in the 20–50&nbsp;MHz range.<ref name="Myhra p. 11"/>

Radar simulations showed a hypothetical Ho 229, with the radar characteristics of the mockup, which had neither metal frame nor the highly reflective engines, approaching the English coast from France flying at {{cvt|885|km/h}} at {{cvt|15|–|30|m}} above the water would still have been visible to an old and by then already retired model of the [[Chain Home]] radar at a distance of 80% that of a [[Messerschmitt Bf 109|Bf 109]], while all other systems showed no significant change.<ref>National Geographic HD : Stealth Fighter - Hitler's Secret Weapons Recreated| Around 40 minutes in</ref>