Editing Convair X-6 (section)

==Development and design==
In May 1946, the [[Nuclear aircraft|Nuclear Energy for the Propulsion of Aircraft]] (NEPA) project was started by the [[United States Army Air Forces]].  Studies under this program were done until May 1951 when NEPA was replaced by the Aircraft Nuclear Propulsion (ANP) program. The ANP program included plans for Convair to modify two B-36s under the '''MX-1589''' project. One of the B-36s was used to study shielding requirements for an airborne reactor, while the other became the X-6.<ref>{{Cite web |last=Wendorf |first=Marcia |date=2019-11-17 |title=Both U.S. and Soviet Attempts at Developing a Nuclear-Powered Aircraft Ended in Failure |url=https://interestingengineering.com/transportation/both-us-and-soviet-attempts-at-developing-a-nuclear-powered-aircraft-ended-in-failure |access-date=2023-04-16 |website=interestingengineering.com |language=en-US}}</ref>

===Nuclear Test Aircraft===

The first modified B-36 was called the Nuclear Test Aircraft (NTA), a B-36H-20-CF (Serial Number 51-5712) that had been damaged in a tornado at [[Carswell AFB]] on September 1, 1952. This plane was redesignated the XB-36H, then the [[Convair B-36#Experiments|NB-36H]] and was modified to carry a 1 [[megawatt]],<ref name="nance">{{Cite report |last=Nance |first=J. C. comp |date=1957-11-01 |title=CALIBRATION OF THE ASTR |osti=4347121 |url=https://www.osti.gov/biblio/4347121 |language=English}}</ref> air-cooled [[nuclear reactor]] in its bomb bay. The reactor, named the Aircraft Shield Test Reactor (ASTR), was operational but did not power the plane. Water, acting as both moderator and coolant, was pumped through the reactor core and then to water-to-air heat exchangers to dissipate the heat to the atmosphere. Its sole purpose was to investigate the effect of radiation on aircraft systems.<ref name="nance"/>

To shield the flight crew, the nose section of the aircraft was modified to include a 12-ton lead and rubber shield. The standard windshield was replaced with one made of {{convert|6|in|cm|adj=mid|-thick}} acrylic glass. The amount of lead and water shielding was variable. Measurements of the resulting radiation levels were then compared with calculated levels to enhance the ability to design optimal shielding with minimum weight for nuclear-powered bombers.<ref>{{Cite web |title=Convair NB-36H airplane, the first aircraft to fly with an operating atomic reactor aboard, August 6, 1956 |url=https://digitalcollections.lib.washington.edu/digital/collection/transportation/id/834/ |access-date=2023-04-16 |website=digitalcollections.lib.washington.edu |language=en}}</ref>

The NTA completed 47 test flights and 215 hours of flight time (during 89 of which the reactor was operated) between September 17, 1955, and March 1957<ref name=nukereview>{{cite book |title=Report to the Congress of the United States – Review of manned aircraft nuclear propulsion program | author=Atomic Energy Commission and Department of Defense |date=February 1963 |publisher= The Comptroller General of the United States | page = 141 |url= http://www.fas.org/nuke/space/anp-gao1963.pdf |access-date= January 24, 2012}}</ref> over [[New Mexico]] and [[Texas]].<ref name=radiationworks>{{Citation | title = Radiation works | archive-date = March 2, 2006 | url = http://www.radiationworks.com/flyingreactor.htm | archive-url = https://web.archive.org/web/20060302180919/http://www.radiationworks.com/flyingreactor.htm | contribution = Nuclear Powered Aircraft | publisher = Brookings Institution}}.</ref> This was the only known airborne reactor experiment by the U.S. with an operational nuclear reactor on board. The NB-36H was scrapped at Fort Worth in 1958 when the Nuclear Aircraft Program was abandoned. Based on the results of the NTA, the X-6 and the entire nuclear aircraft program was abandoned in 1961.<ref>{{Cite web |last=Hubbard |first=Bryan |date=2022-06-01 |title=The US Air Force's Bid to Develop Nuclear-Powered Aircraft |url=https://www.military.com/history/atomic-air-power.html |access-date=2023-04-16 |website=Military.com |language=en}}</ref>

===Development plans===
[[File:ebr-1.zdv.jpg|right|thumb|[[Experimental Breeder Reactor I]] in [[Idaho]], the first power reactor, now a museum. The reactor is in the building top right, the two structures lower left are reactors from the Aircraft Nuclear Propulsion Project]]
Had the program progressed, follow-on aircraft would have been based on the successor to the B-36, Convair's swept-wing [[Convair YB-60|B-60]].<ref name=monteview>{{Citation | publisher = Airfields Freeman | contribution-url = https://www.airfieldsfreeman.com/ID/Airfields_ID_N.htm | title = [[Abandoned & Little-Known Airfields]] | contribution = Test Area North, Monteview, ID}}.</ref>

The X-6 would have been powered by [[General Electric J47#Nuclear-powered X39|General Electric X-39]] engines (J47 engines modified to use nuclear energy as fuel), utilizing a P-1 reactor.<ref>{{Citation | publisher = DBS corp | url = http://users.dbscorp.net/jmustain/X6.htm | title = Convair X-6 | url-status = dead | archive-url = https://web.archive.org/web/20120206072428/http://users.dbscorp.net/jmustain/X6.htm | archive-date = February 6, 2012 | df = mdy-all }}.</ref> In a nuclear jet engine, the reactor core was used as a heat source for the turbine's air flow, instead of burning [[jet fuel]]. One disadvantage of the design was that, since the airflow through the engine was used to cool the reactor, this airflow had to be maintained even after the aircraft had landed and parked.<ref name=monteview/> GE built two prototype engines, which can be seen outside the [[Experimental Breeder Reactor I]] in [[Arco, Idaho]].<ref name = radiationworks />

A large, {{convert|350|ft|m|abbr=on}} wide hangar was built at Test Area North, part of the National Reactor Testing Station (now part of the [[Idaho National Laboratory]]; [[Monteview, Idaho|Monteview]]) to house the X-6 project, but the project was canceled before the planned {{convert |15000|ft|m| abbr = on|-2}} runway was built, necessitated by the expected weight of the nuclear-powered aircraft.<ref name=monteview />