Editing Lightcraft (section)

==Types==

===Laser-powered propulsion===
[[File:Lightcraft.png|thumb|250px|Profile view of a laser Lightcraft type 200]]
First small-scale models used [[laser propulsion]] which is a technique still in early stages of development. Lightcraft prototypes are made of solid [[aluminium]] machined [[Rotational symmetry#Rotational symmetry with respect to any angle shape|axisymmetrically]]. The nose is shaped as a [[Nose cone design|blunted cone]] for [[Aerodynamics|aerodynamical]] purpose. The rim has an annular air [[Intake|inlet]]. The aft is a funnel polished as a [[Curved mirror#Concave mirrors|concave mirror]] with a pointy tail in the middle extending back out of the body, acting as a [[parabolic reflector]].

A ground-based [[laser]] aims a high power pulse to the mirror stern. The beam is reflected and focuses to heat the air at an extremely high temperature up to 30,000 degrees, transforming it in a plasma that violently expands, pushing the craft forward. Air is renewed through the inlet and the cycle is repeated at high frequency, acting as an external [[pulse detonation engine]] producing thrust.<ref name="Centauri-Dreams">{{cite web
 |last1=Gilster |first1=Paul
 |title=Lightcraft: A Laser Push to Orbit
 |date=14 September 2009
 |website=Centauri Dreams
 |url=https://www.centauri-dreams.org/2009/09/14/lightcraft-a-laser-push-to-orbit/
 |access-date=2018-04-05
}}</ref>

In April 1997, tests by Leik Myrabo in cooperation with the [[United States Army|US Army]] at [[White Sands Missile Range]] demonstrated the basic feasibility to propel objects in this way, using a 10-kW ground-based pulsed [[carbon dioxide laser]] (1&nbsp;kJ per pulse, 30&nbsp;μs pulse at 10&nbsp;Hz frequency). The test succeeded in reaching over one hundred feet, which compares to [[Robert Goddard (scientist)|Robert Goddard]]'s first test flight of his rocket design.<ref name="Myrabo 1st test" />

In October 2000, a new flight record was set with a flight lasting 10.5 seconds and reaching 71 meters (233&nbsp;feet) using the same laser, but this time providing an on-board plastic ablative propellant, and rotating the body around its axis at high speed (over 10,000&nbsp;[[Revolutions per minute|rpm]]) to stabilize the craft with a [[gyroscope|gyroscopic effect]].<ref name="Myrabo 2nd test">{{cite conference
 |last1=Myrabo |first1=Leik N.
 |title=World record flights of beam-riding rocket lightcraft - Demonstration of 'disruptive' propulsion technology
 |date=July 2001
 |conference=37th Joint Propulsion Conference and Exhibit
 |location=Salt Lake City, UT
 |book-title=AIAA 2001-3798
 |url=http://ayuba.fr/pdf/myrabo2001a.pdf
 |doi=10.2514/6.2001-3798
}}
</ref><ref name="space.com 2000">{{cite web
 |author=Leonard David
 |title=Laser-Boosted Rocket Sets Altitude Record
 |date=2 November 2000
 |website=space.com
 |url=https://www.space.com/businesstechnology/technology/laser_craft_001103.html
 |url-status=dead
 |archive-date=13 April 2001
 |archive-url=https://web.archive.org/web/20010413132547/http://www.space.com/businesstechnology/technology/laser_craft_001103.html
 |access-date=5 April 2018
 }}</ref><ref name="NewSpace 2010">{{YouTube|id=dV75c8tTFdk&feature=youtu.be&t=10m|title=NewSpace 2010 – Approaching Warp Speed: Advanced Space Propulsion}} (Lightcraft presentation at time 10:00–32:00).</ref>

===Microwave-powered and MHD propulsion===
More advanced concepts of the Lightcraft replace the laser pulses by a [[microwave]] beam or [[maser]] that can still be ground-based, or alternatively put into [[orbit]], the beams being emitted from above the ascending craft by a series of [[space-based solar power]] [[satellite]]s that could more easily keep track of the Lightcraft along its curved [[Ballistics|ballistic trajectory]].

The microwave beam [[Detonation|detonates]] the air below the craft exactly like the laser version, but some energy from the beam is also diverted and converted on board by high-power [[rectenna]]s into [[electricity]] to power an [[Magnetohydrodynamic drive#Typology|external-flow airbreathing MHD drive]] called by Myrabo an ''MHD slipstream accelerator''.<ref name="Myrabo 1999">{{cite conference
 | last1 = Myrabo | first1 =  L. N.
 | last2 = Kerl | first2 = J.M.
 | title = 35th Joint Propulsion Conference and Exhibit
 | display-authors=etal
 | date = June 1999
 | chapter = MHD slipstream accelerator investigation in the RPI hypersonic shock tunnel
 | conference = 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
 | book-title = AIAA-1999-2842
 | location = Los Angeles, CA
 | chapter-url = http://ayuba.fr/pdf/myrabo1999.pdf
 | doi = 10.2514/6.1999-2842 
}}</ref><ref name="Myrabo 2000a">{{cite conference
 | last1 = Myrabo | first1 =  L. N.
 | title = 38th Aerospace Sciences Meeting and Exhibit
 | display-authors=etal
 | date = January 2000
 | chapter = Experimental investigation of a 2-D MHD slipstream generator and accelerator with freestream Mach = 7.6 and T(0) = 4100 K
 | conference = 38th Aerospace Sciences Meeting and Exhibit 
 | book-title =  AIAA-00-0446
 | location = Reno, NV
 | chapter-url = http://ayuba.fr/pdf/myrabo2000a.pdf
 | doi = 10.2514/6.2000-446 
}}</ref><ref name="Myrabo 2000b">{{cite conference
 | last1 = Myrabo | first1 =  L. N.
 | title = 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
 | display-authors=etal
 | date = July 2000
 | chapter = Experimental Investigation of a 2-D MHD Slipstream Accelerator and Generator
 | conference = 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
 | book-title = AIAA-00-3486
 | location = Huntsville, AL
 | chapter-url = http://ayuba.fr/pdf/myrabo2000b.pdf
 | doi = 10.2514/6.2000-3486
}}</ref><ref name="Myrabo 2001b">{{cite conference
 |last1=Myrabo |first1=L.N.
 |display-authors=etal
 |date = July 2001
 |title = Experimental Investigation of a 2-D MHD Slipstream Accelerator: Progress Report
 |conference = 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
 |book-title = AIAA-01-3799
 |location = Salt Lake City, UT
 |url = http://ayuba.fr/pdf/myrabo2001b.pdf
 |doi = 10.2514/6.2001-3799
}}</ref>

As an MHD accelerator works only with an [[Electrical resistivity and conductivity|electrically conductive]] medium, some of the incoming microwaves are also diverted within the Lightcraft through a series of transparent windows and mirror sections, then re-emitted in the air near the [[electrode]]s of the MHD accelerators located around the rim. The air becomes ionized in these places, allowing MHD interaction of [[Lorentz force]]s to actively control the [[airflow]] around a discoidal shape that otherwise (i.e. passively) has very bad aerodynamical properties due to its largest surface, a flat plate, being perpendicular to the flow.<ref name="Myrabo plate">{{cite conference
 |last1=Toro |first1=P.G.P.
 |last2=Rusak |first2=Z.
 |last3=Nagamatsu |first3=H.T.
 |last4=Myrabo |first4=L.N.
 |title=36th AIAA Aerospace Sciences Meeting and Exhibit
 |chapter=Hypersonic flow over a flat plate
 |date=January 1998
 |conference=36th AIAA Aerospace Sciences Meeting and Exhibit
 |book-title=AIAA-98-0683
 |location=Reno, NV
 |chapter-url=http://ayuba.fr/pdf/myrabo1998b.pdf
 |doi=10.2514/6.1998-683  
}}</ref>

Finally, a laser or some part of the microwaves are also focused as a ''plasma torch'' at some distance above the Lightcraft, creating an [[Drag-reducing aerospike|aerospike]] that detaches and mitigates the bow [[shock wave]] ahead of the craft when it evolves at [[supersonic speed]]s, lowering heat transfert to the walls. The distance and intensity of the aerospike are tuned according to the [[atmospheric pressure]], [[temperature gradient]]s and [[velocity]] of the airflow to actively shape the shock wave so the [[boundary layer]] can be optimally controlled by the radial MHD slipstream accelerators.<ref name="Myrabo airspike">{{cite conference
 |last1=Toro |first1=P.
 |last2=Myrabo |first2=L.
 |last3=Nagamatsu |first3=H.
 |title=36th AIAA Aerospace Sciences Meeting and Exhibit
 |chapter=Pressure investigation of the hypersonic 'Directed-Energy Air Spike' inlet at Mach number 10 with arc power up to 70 kW
 |date=January 1998
 |conference=36th AIAA Aerospace Sciences Meeting and Exhibit
 |location=Reno, NV
 |chapter-url=http://ayuba.fr/pdf/myrabo1998c.pdf
 |doi=10.2514/6.1998-991  
}}</ref><ref name="Myrabo 2001c">{{cite conference
 |last1=Bracken |first1=R.M.
 |last2=Myrabo |first2=L.N.
 |last3=Nagamatsu |first3=H.T.
 |last4=Meloney |first4=E.D.
 |last5=Schneider |first5=M.N.
 |title=37th Joint Propulsion Conference and Exhibit
 |date=July 2001
 |chapter=Experimental and computational investigation of an electric arc air-spike in hypersonic flow with drag measurements
 |conference=35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
 |book-title=AIAA 01-3797
 |location=Salt Lake City, UT
 |chapter-url=http://ayuba.fr/pdf/myrabo2001c.pdf
 |doi=10.2514/6.2001-3797
}}</ref><ref name="Myrabo 2005">{{cite journal
 |last1=Minucci |first1=M.A.S.
 |last2=Toro |first2=P.G.P.
 |last3=Oliveira |first3=A.C.
 |last4=Ramos |first4=A.G.
 |last5=Chanes |first5=J.B.
 |last6=Pereira |first6=A.L.
 |last7=Nagamatsu |first7=H.M.T.
 |last8=Myrabo |first8=L.N.
 |title=Laser-Supported Directed-Energy 'Air Spike' in Hypersonic Flow
 |date=January 2005
 |journal=Journal of Spacecraft and Rockets
 |volume=42
 |issue=1
 |pages=51–57
 |doi=10.2514/1.2676
 |url=http://ayuba.fr/pdf/myrabo2005.pdf
 |bibcode=2005JSpRo..42...51M}}</ref>

The Lightcraft concept thus combines [[magnetohydrodynamics|magnetohydrodynamic]] [[active flow control]] and beam-powered propulsion mechanisms to enable [[hypersonic flight]], solving the classical problem of aerial MHD propulsion (i.e. lack of a light power source offering enough energy to feed such systems) by outsourcing the power source. Using microwaves instead of a laser allows four combined actions: propulsive detonation, shockwave mitigation, ionization control and electrical feeding of MHD drives.<ref name="Myrabo book">{{cite book
 |last1=Myrabo |first1=Leik N.
 |last2=Lewis |first2=John S.
 |title=Lightcraft Flight Handbook LTI-20: Hypersonic Flight Transport for an Era Beyond Oil
 |date=May 2009
 |publisher=Collector's Guide Publishing
 |isbn=978-1926592039
}}</ref>