The Black Horse was a study concept for a proposed winged single-stage to orbit

spaceplane A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes te ...

that would use aerial refueling to greatly reduce the size of the spacecraft, to about the size of an F-16 Fighting Falcon. The original concept was proposed in 1993 by

US Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sig ...

Captain Mitchell Burnside Clapp, who was familiar with the Air Force's use of aerial refueling to extend the performance of combat aircraft. The concept was further developed by others, including a smaller concept developed by

Robert Zubrin Robert Zubrin (; born April 9, 1952) is an American aerospace engineer, author, and advocate for human exploration of Mars. He and his colleague at Martin Marietta, David Baker, were the driving force behind Mars Direct, a proposal in a 1990 res ...

, named the Black Colt. Clapp left the Air Force in 1996 and partnered with Zubrin to form Pioneer Rocketplane, who proposed a slightly larger version known as Pathfinder.

Black Horse Development

Clapp proposed Black Horse as a solution to the Air Force's ongoing TransAtmospheric Vehicle (TAV) mission. The concept was picked up by the Phillips Laboratory, and over the winter of 1993-94 they carried out a six-week study with WJ Schafer Associates and Conceptual Research Corporation (an aircraft design firm) into what was now known as the Aerial Propellant Transfer (APT) concept. APT was based on using as many off-the-shelf components as possible and considered a wide variety of possible propellants. Wishing to use only non-cryogenic fuels, they favored the use of conventional

JP-5 Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial av ...

jet fuel with

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

as the

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...

. Other mixes considered, mostly for comparison purposes, were

liquid hydrogen Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully l ...

(LH2) and

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

(LOX),

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

/LOX, and

RP-1 RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is s ...

/LOX. Although the performance of the alternate fuels was higher, they all included at least one cryogenic component and were much less dense. Using peroxide had the additional advantage of cooling the combustion, which allowed the use of conventional JP-5 rather than the more expensive RP-1. The study demonstrated that Black Horse would outperform any vertical take-off/horizontal landing concept no matter what fuel it used. The study also noted that the speed that the aerial fuel transfer took place was a key input to the overall performance of the system. Black Horse was deliberately designed to use existing

tanker aircraft This is a list of tanker aircraft used for aerial refuelling of another aircraft whilst in powered flight. Refueling methods ;Looped hose: The first commercial method employed a hose which was held slack in a trailing half-loop behind both air ...

, specifically the KC-135Q and T models, which had fuel tanks completely separate from the aircraft's own fuel system (most models allowed the 135's engines to draw from the tanks). However, performance was slightly increased if the transfer took place in the supersonic regime at Mach 3.0, and dramatically increased, almost doubled, if it was hypersonic at Mach 5.5.

Black Colt

The concept was also picked up by Zubrin, who was then working at Martin Marietta, who carried out their own design series from January to May 1994. This developed the smaller Black Colt concept. Clapp and Zubrin later wrote an extensive article on the concepts in the June 1995 edition of ''Analog'' magazine. The Black Colt would take off with a tank of fuel, but load oxidizer while in the air. Zubrin considered the Black Colt to be a more feasible concept, as it would fly at a much lower speed. Clapp partnered with Zubrin to form Pioneer Rocketplane, who proposed a slightly larger version known as Pathfinder.

Rocketplane XS

A similar launcher, Rocketplane XS, has been proposed by

Rocketplane Global Inc. Rocketplane Global Inc. is a reusable rocketplane aerospace design and development company incorporated in Delaware. History Rocketplane Limited, Inc. was incorporated under the laws of the state of Oklahoma on 16 July 2001. After going bankrup ...

Rocketplane XS
, Rocketplane Global Inc. web page.

References

Bibliography

External links