Editing Atmospheric entry (section)

==High-drag suborbital entry==
In 2004, aircraft designer [[Burt Rutan]] demonstrated the feasibility of a shape-changing airfoil for reentry with the sub-orbital [[SpaceShipOne]]. The wings on this craft rotate upward into the ''feathered configuration'' that provides a [[shuttlecock]] effect. Thus SpaceShipOne achieves much more aerodynamic drag on reentry while not experiencing significant thermal loads.

The configuration increases drag, as the craft is now less streamlined and results in more atmospheric gas particles hitting the spacecraft at higher altitudes than otherwise. The aircraft thus slows down more in higher atmospheric layers which is the key to efficient reentry. Secondly, the aircraft will ''automatically'' orient itself in this state to a high drag attitude.<ref>{{cite web|url=http://science.howstuffworks.com/spaceshipone4.htm|title=How SpaceShipOne Works|date=20 June 2004|access-date=April 23, 2011|archive-date=January 12, 2012|archive-url=https://web.archive.org/web/20120112003232/http://science.howstuffworks.com/spaceshipone4.htm|url-status=live}}</ref>

However, the velocity attained by SpaceShipOne prior to reentry is much lower than that of an orbital spacecraft, and engineers, including Rutan, recognize that a feathered reentry technique is not suitable for return from orbit.

On 4 May 2011, the first test on the [[SpaceShipTwo]] of the feathering mechanism was made during a glideflight after release
from the White Knight Two. Premature deployment of the feathering system was responsible for the 2014 [[VSS Enterprise crash|VSS ''Enterprise'' crash]], in which the aircraft disintegrated, killing the co-pilot.

The feathered reentry was first described by [[Dean R. Chapman|Dean Chapman]] of [[NACA]] in 1958.<ref name="NACA TN 4276">{{cite journal | url=http://naca.larc.nasa.gov/reports/1958/naca-tn-4276/naca-tn-4276.pdf | title=An approximate analytical method for studying reentry into planetary atmospheres | author=Chapman, Dean R. | journal=NACA Technical Note 4276 | date=May 1958 | page=38 | url-status=dead | archive-url=https://web.archive.org/web/20050127060632/http://naca.larc.nasa.gov/reports/1958/naca-tn-4276/naca-tn-4276.pdf | archive-date=January 27, 2005 | access-date=February 3, 2006 }}</ref> In the section of his report on ''Composite Entry'', Chapman described a solution to the problem using a high-drag device:

{{quote|
It may be desirable to combine lifting and nonlifting entry in order to achieve some advantages... For landing maneuverability it obviously is advantageous to employ a lifting vehicle. The total heat absorbed by a lifting vehicle, however, is much higher than for a nonlifting vehicle... Nonlifting vehicles can more easily be constructed... by employing, for example, a large, light drag device... The larger the device, the smaller is the heating rate.

Nonlifting vehicles with shuttlecock stability are advantageous also from the viewpoint of minimum control requirements during entry.

... an evident composite type of entry, which combines some of the desirable features of lifting and nonlifting trajectories, would be to enter first without lift but with a... drag device; then, when the velocity is reduced to a certain value... the device is jettisoned or retracted, leaving a lifting vehicle... for the remainder of the descent.
}}