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Douglas X-3 Stiletto

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|status = Preserved at [[National Museum of the United States Air Force]]
 
|status = Preserved at [[National Museum of the United States Air Force]]
 
|unit cost =
 
|unit cost =
|primary user = United States Air Force
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|primary user = [[United States Air Force]]
 
|more users = [[National Advisory Committee for Aeronautics|NACA]]
 
|more users = [[National Advisory Committee for Aeronautics|NACA]]
 
|developed from =
 
|developed from =
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The Douglas X-3 Stiletto was the sleekest of the early experimental aircraft, but its research accomplishments were not those originally planned. It was originally intended for advanced Mach 2 turbojet propulsion testing, but it fell largely into the category of configuration explorers, as its performance (due to inadequate engines) never met its original performance goals.<ref name=NTRS>Hallion, Richard P. [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100025896_2010028361.pdf "The NACA, NASA, and the Supersonic-Hypersonic Frontier."] ''NASA Technical Reports.'' Retrieved: 7 September 2011.</ref> The goal of the aircraft was ambitious&mdash;it was to take off from the ground under its own power, climb to high altitude, maintain a sustained cruise speed of Mach&nbsp;2, then land under its own power. The aircraft was also to test the feasibility of [[Aspect ratio (aeronautics)|low-aspect-ratio wings]], and the large-scale use of titanium in aircraft structures. The design of the Douglas X-3 Stiletto is the subject of U.S. Design Patent #172,588 granted on July 13, 1954 to Frank N. Fleming and Harold T. Luskin and assigned to the Douglas Aircraft Company, Inc.
 
The Douglas X-3 Stiletto was the sleekest of the early experimental aircraft, but its research accomplishments were not those originally planned. It was originally intended for advanced Mach 2 turbojet propulsion testing, but it fell largely into the category of configuration explorers, as its performance (due to inadequate engines) never met its original performance goals.<ref name=NTRS>Hallion, Richard P. [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100025896_2010028361.pdf "The NACA, NASA, and the Supersonic-Hypersonic Frontier."] ''NASA Technical Reports.'' Retrieved: 7 September 2011.</ref> The goal of the aircraft was ambitious&mdash;it was to take off from the ground under its own power, climb to high altitude, maintain a sustained cruise speed of Mach&nbsp;2, then land under its own power. The aircraft was also to test the feasibility of [[Aspect ratio (aeronautics)|low-aspect-ratio wings]], and the large-scale use of titanium in aircraft structures. The design of the Douglas X-3 Stiletto is the subject of U.S. Design Patent #172,588 granted on July 13, 1954 to Frank N. Fleming and Harold T. Luskin and assigned to the Douglas Aircraft Company, Inc.
   
Construction of a pair of X-3s was approved on 30 June 1949. During development, the X-3's planned [[Westinghouse J46]] engines were unable to meet the thrust, size and weight requirements, so lower-thrust [[Westinghouse J34]] turbojets were substituted, producing only 4,900&nbsp;lbf (21.8&nbsp;kN) of thrust with afterburner rather than the planned 7,000&nbsp;lbf (31.3&nbsp;kN). The first aircraft was completed and delivered to Edwards Air Force Base, California, on 11 September 1952.
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Construction of a pair of X-3s was approved on 30 June 1949. During development, the X-3's planned [[Westinghouse J46]] engines were unable to meet the thrust, size and weight requirements, so lower-thrust [[Westinghouse J34]] turbojets were substituted, producing only 4,900&nbsp;lbf (21.8&nbsp;kN) of thrust with afterburner rather than the planned 7,000&nbsp;lbf (31.3&nbsp;kN). The first aircraft was completed and delivered to [[Edwards Air Force Base]], California, on 11 September 1952.
   
 
The X-3 featured an unusual slender, streamlined shape having a very long, gently-tapered nose and small [[trapezoidal wing]]s. The aim was to create the thinnest and most slender shape possible in order to achieve low drag at supersonic speeds. The extended nose was to allow for the provision of test equipment while the semi-buried cockpit and windscreen were designed to alleviate the effects of "[[Aerodynamic heating|thermal thicket]]" conditions. The low aspect ratio, unswept wings were designed for high speed and later the Lockheed design team used data from the X-3 tests for the similar F-104 Starfighter wing design. Due to both engine and airframe problems, the partially completed second aircraft was cancelled, and its components were used for spare parts.<ref name= "Winchester p. 89.">Winchester 2005, p. 89.</ref>
 
The X-3 featured an unusual slender, streamlined shape having a very long, gently-tapered nose and small [[trapezoidal wing]]s. The aim was to create the thinnest and most slender shape possible in order to achieve low drag at supersonic speeds. The extended nose was to allow for the provision of test equipment while the semi-buried cockpit and windscreen were designed to alleviate the effects of "[[Aerodynamic heating|thermal thicket]]" conditions. The low aspect ratio, unswept wings were designed for high speed and later the Lockheed design team used data from the X-3 tests for the similar F-104 Starfighter wing design. Due to both engine and airframe problems, the partially completed second aircraft was cancelled, and its components were used for spare parts.<ref name= "Winchester p. 89.">Winchester 2005, p. 89.</ref>
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The first X-3 "hop" was made on 15 October 1952, by Douglas test pilot William Bridgeman. During a high-speed taxi test, Bridgeman lifted the X-3 off the ground and flew it about 1&nbsp;mi (1.6&nbsp;km) before settling back onto the lakebed. The official first flight was made by Bridgeman on 20 October, and lasted about 20 minutes. He made a total of 26 flights (counting the hop) by the end of the Douglas tests in December 1953. These showed that the X-3 was severely underpowered and difficult to control. Its takeoff speed was an unusually high 260&nbsp;kts (482&nbsp;km/h). More seriously, the X-3 did not approach its planned top speed. Its first supersonic flight required that the airplane make a 15° dive to reach Mach&nbsp;1.1. The X-3's fastest flight, made on 28 July 1953, reached Mach&nbsp;1.208 in a 30° dive.<ref name= "Winchester p. 88."/> A plan to re-engine the X-3 with rocket motors was considered but eventually dropped.<ref name= "Winchester p. 89."/>
 
The first X-3 "hop" was made on 15 October 1952, by Douglas test pilot William Bridgeman. During a high-speed taxi test, Bridgeman lifted the X-3 off the ground and flew it about 1&nbsp;mi (1.6&nbsp;km) before settling back onto the lakebed. The official first flight was made by Bridgeman on 20 October, and lasted about 20 minutes. He made a total of 26 flights (counting the hop) by the end of the Douglas tests in December 1953. These showed that the X-3 was severely underpowered and difficult to control. Its takeoff speed was an unusually high 260&nbsp;kts (482&nbsp;km/h). More seriously, the X-3 did not approach its planned top speed. Its first supersonic flight required that the airplane make a 15° dive to reach Mach&nbsp;1.1. The X-3's fastest flight, made on 28 July 1953, reached Mach&nbsp;1.208 in a 30° dive.<ref name= "Winchester p. 88."/> A plan to re-engine the X-3 with rocket motors was considered but eventually dropped.<ref name= "Winchester p. 89."/>
   
With the completion of the contractor test program in December 1953, the X-3 was delivered to the United States Air Force. The poor performance of the X-3 meant only an abbreviated program would be made, to gain experience with low aspect ratio wings. [[Lieutenant Colonel]] [[Frank Kendall Everest, Jr.|Frank Everest]] and [[Major]] [[Chuck Yeager]] each made three flights. Although flown by Air Force pilots, these were counted as [[National Advisory Committee for Aeronautics|NACA]] flights. With the last flight by Yeager in July 1954, NACA made plans for a limited series of research flights with the X-3. The initial flights looked at longitudinal stability and control, wing and tail loads, and pressure distribution.
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With the completion of the contractor test program in December 1953, the X-3 was delivered to the [[United States Air Force]]. The poor performance of the X-3 meant only an abbreviated program would be made, to gain experience with low aspect ratio wings. [[Lieutenant Colonel]] [[Frank Kendall Everest, Jr.|Frank Everest]] and [[Major]] [[Chuck Yeager]] each made three flights. Although flown by Air Force pilots, these were counted as [[National Advisory Committee for Aeronautics|NACA]] flights. With the last flight by Yeager in July 1954, NACA made plans for a limited series of research flights with the X-3. The initial flights looked at longitudinal stability and control, wing and tail loads, and pressure distribution.
   
 
NACA pilot [[Joseph A. Walker]] made his pilot checkout flight in the X-3 on 23 August 1954, then conducted eight research flights in September and October. By late October, the research program was expanded to include lateral and directional stability tests. In these tests, the X-3 was abruptly rolled at [[transonic]] and supersonic speeds, with the rudder kept centered. Despite its shortcomings, the X-3 was ideal for these tests. The mass of its engines, fuel and structure was concentrated in its long, narrow fuselage, while its wings were short and stubby. As a result, the X-3 was "loaded" along its fuselage, rather than its wings. This was typical of the fighter aircraft then in development or testing.
 
NACA pilot [[Joseph A. Walker]] made his pilot checkout flight in the X-3 on 23 August 1954, then conducted eight research flights in September and October. By late October, the research program was expanded to include lateral and directional stability tests. In these tests, the X-3 was abruptly rolled at [[transonic]] and supersonic speeds, with the rudder kept centered. Despite its shortcomings, the X-3 was ideal for these tests. The mass of its engines, fuel and structure was concentrated in its long, narrow fuselage, while its wings were short and stubby. As a result, the X-3 was "loaded" along its fuselage, rather than its wings. This was typical of the fighter aircraft then in development or testing.
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==Survivors==
 
==Survivors==
*The sole X-3 was transferred in 1956 to the [[National Museum of the United States Air Force]] at Wright-Patterson Air Force Base, Ohio.<ref>''United States Air Force Museum Guidebook'' 1975, p. 88.</ref> {{As of|2015}} it is on display in the Museum's Research & Development Gallery.<ref name= "Winchester p. 88."/>
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*The sole X-3 was transferred in 1956 to the [[National Museum of the United States Air Force]] at [[Wright-Patterson Air Force Base]], Ohio.<ref>''United States Air Force Museum Guidebook'' 1975, p. 88.</ref> {{As of|2015}} it is on display in the Museum's Research & Development Gallery.<ref name= "Winchester p. 88."/>
   
 
==Specifications (X-3)==
 
==Specifications (X-3)==
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{{aircontent|
 
{{aircontent|
 
|related=
 
|related=
* F-104 Starfighter
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* [[F-104 Starfighter]]
 
|similar aircraft=*[[Bristol 188]]
 
|similar aircraft=*[[Bristol 188]]
 
|lists=
 
|lists=
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