Editing Martin X-23 PRIME

{{More sources|date=September 2024}}{{Short description|American experimental aircraft}}
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{{Infobox aircraft
 |name = X-23A PRIME
 |image = File:X23_PRIME.JPG
 |caption = Preserved X-23A PRIME at USAF Museum, Dayton, Ohio
 |type = Lifting body
 |national_origin = United States
 |manufacturer = [[Martin Marietta]]
 |designer =
 |first_flight = 21 December 1966
 |introduction =
 |retired = 19 April 1967
 |produced =
 |number_built = 3
 |status = Out of service
 |unit cost =
 |primary_user = [[United States Air Force]]
 |more_users =
 |developed_from =
 |variants = [[Martin Marietta X-24]]
}}

The '''Martin X-23A PRIME''' (Precision Reentry Including Maneuvering reEntry) (SV-5D) is a small [[lifting body|lifting-body]] [[re-entry vehicle]] tested by the [[United States Air Force]] in the mid-1960s. Unlike [[ASSET (spacecraft)|ASSET]], primarily used for structural and heating research, the X-23A PRIME was developed to study the effects of maneuvering during re-entry of [[Earth's atmosphere]], including cross-range maneuvers up to {{cvt|617|nmi|mi km|0}} from the [[Trajectory of a projectile|ballistic]] track.

== Design ==
Each X-23A was constructed from [[titanium]], [[beryllium]], [[stainless steel]], and [[aluminium|aluminum]]. The craft consisted of two sections—the aft main structure and a removable forward "glove section". The structure was completely covered with a Martin-developed [[Ablation|ablative]] [[heat shield]] {{cvt|0.75|to|2.75|in|0}} thick, and the [[Nose cone|nose cap]] was constructed of [[Pyrolytic carbon|carbon]] [[Phenol formaldehyde resin|phenolic]] material.<ref name="NASA">{{cite book |last1=Jenkins |first1=Dennis R. |last2=Landis |first2=Tony |last3=Miller |first3=Jay |title=AMERICAN X-VEHICLES An Inventory—X-1 to X-50 : Monographs in Aerospace History No. 31, SP-2003-4531 |date=June 2003 |publisher=National Aeronautics and Space Administration |location=Washington, DC |page=30}}</ref><ref name=Miller>{{cite book |last1=Miller |first1=Jay |title=The X-planes : X-1 to X-29 |date=1983 |publisher=Speciality Press |location=Marine on St. Croix |isbn=0933424353 |pages=148–149}}</ref>

[[Aerodynamic]] control was provided by a pair of {{cvt|12|x|12|in|0}} lower [[Flap (aircraft)|flaps]], and fixed upper flaps and [[Rudder#Aircraft rudders|rudder]]s. A [[nitrogen]]-gas [[reaction control system]] was used outside the atmosphere. At [[Mach number|Mach 2]] a [[drogue]] [[ballute]] deployed and slowed the vehicle's descent. As it deployed, its cable sliced the upper structure of the main equipment bay, allowing a {{cvt|47|ft|0}} recovery [[Parachute|chute]] to deploy. It would then be [[Mid-air retrieval|recovered in midair]] by a specially-equipped [[Lockheed C-130 Hercules|JC-130B]] Hercules aircraft.<ref name="NASA"/><ref name=Miller/>

== Flight testing ==
The first PRIME vehicle was launched from [[Vandenberg AFB]] on 21 December 1966 atop an [[Atlas SLV-3]] [[launch vehicle]]. This mission simulated a [[low Earth orbit]] reentry with a zero cross-range. The ballute deployed at {{cvt|99850|ft|0}}, though the recovery parachute failed to completely deploy. The vehicle crashed into the Pacific Ocean.<ref name="NASA"/><ref name=Miller/>

The second vehicle was launched on 5 March 1967. This flight simulated a 654-mile (1053-kilometre) cross-range reentry, and banking at hypersonic speeds. The recovery parachute deployed properly and was located by two of the deployed recovery aircraft. During an inspection fly-by of the descending parachute system it was seen that reefing cutters had failed to actuate. These cutters are on the harness suspending the vehicle from the parachute to ensure stability of the vehicle behind the JC-130B recovery aircraft during reel-in, and permit safely boarding the vehicle. As a result, the parachute and vehicle were allowed to descend to the sea. Subsequently, the vehicle separated from its flotation "balloon" in the rough seas and, with the parachute, sank before a nearby ship could arrive to retrieve it from the ocean.<ref name="NASA"/><ref name=Miller/>

The final PRIME mission was flown on 19 April 1967, and simulated re-entry from low Earth orbit with a {{cvt|617|nmi|mi km|0}} cross-range. This time, all systems performed perfectly, and the X-23A was successfully recovered. An inspection by a USAF-Martin team reported the craft "ready to fly again", although no later missions were carried out. The third X-23A is now on display at the [[National Museum of the United States Air Force]] at [[Wright-Patterson Air Force Base]] in Ohio.<ref name="NASA"/><ref name=Miller/>

== Specifications (X-23A) ==
{{Aircraft specs
|ref=The X-planes : X-1 to X-29<ref name=Miller/><ref>{{cite web |url=https://www.researchgate.net/publication/276294924 |url-status=dead |archive-url=https://web.archive.org/web/20210501004337/https://www.researchgate.net/publication/276294924_Martin_X-24A_Lifting_Body |archive-date=2021-05-01 |title=Martin X-24A Lifting Body}}</ref>
|prime units?=kts
|length ft= 6
|length in= 8
|span ft= 3
|span in= 10 
|height ft= 2
|height in= 10
|gross weight lb= 894
|eng1 name=[[Nitrogen]] gas [[Reaction control system|reaction control thruster]]s
|max speed kts=14388
|max speed note=
|max speed mach=25
|range miles=
|range km=
|more performance=
* '''Hypersonic L/D Ratio:''' 1:1{{citation needed|date=December 2020}}
|avionics=
}}

==See also==
{{aircontent|
|related=
|similar aircraft=
*[[BOR-4|Molniya BOR-4]]
*[[ASSET (spacecraft)|ASSET]]
|lists=
|see also=
}}

== References==
{{reflist}}

==External links==
{{commons category|Martin Marietta X-23}}
*[https://web.archive.org/web/20090212224747/http://astronautix.com/craft/prime.htm Encyclopedia Astronautica]
*[https://www.youtube.com/watch?v=gDAPjumZA1s Video] Atlas X-38 Prototype Arrival (PRIME/X-23), Unloading, Mating and Launch

{{Martin aircraft}}
{{X-planes}}

{{DEFAULTSORT:Martin X-23 Prime}}
[[Category:United States military gliders]]
[[Category:Lifting bodies]]
[[Category:Spaceplanes]]
[[Category:1960s United States experimental aircraft]]
[[Category:Unmanned aerial vehicles of the United States]]
[[Category:Martin aircraft|X-23]]
[[Category:Aircraft first flown in 1966]]
[[Category:Twin-tail aircraft]]