OTRAG (rocket)

OTRAG (rocket)

The OTRAG rocket was a modular satellite-delivery rocket developed by the OTRAG company in the 1970s and 80s. The OTRAG rocket was to become a rocket built up from several mass-produced units, intended to carry satellites with a weight of 1-10 tons or more into orbit. Mass production meant that the vehicle was projected to have been 10x cheaper than conventional vehicles of similar capability.

Design

Various OTRAG rockets could be built up from the company's CRPUs (Common Rocket Propulsion Unit). A sounding rocket would bundle four or more CRPUs in parallel, topped with the payload. An orbital launcher would use dozens to hundreds of CRPUs, depending on payload mass. The launcher would then stage by dropping outer CRPUs, leaving the interior ones to continue with payload.

A CRPU was essentially a steel tube, 27 cm in diameter and 16 meters long, joined from a few shorter tubes. The CRPU was divided into three sections by aluminum bulkheads, with additional stiffening rings between bulkheads. Forward, the majority of the tube contained a mixture of nitric acid and nitrogen tetroxide oxidizers. Next was a section of kerosene fuel. This was commercial-grade kerosene, not the more expensive RP-1. Last was the engine section. A fuel line carried nitric acid around the kerosene, into the engine.

The design of the CRPU was extremely simple. The tubing was strong enough that the propellants were fed to the engine by pressure alone. This eliminated the need for turbopumps. The engine was ablatively cooled, eliminating the need for fine fuel passages and heat-resistant kerosene. The engine did not gimbal; instead, the vehicle was steered by throttling one side's CRPUs versus the opposite side. Thus, the engine was simply built into the tube walls, with the only mechanisms being the throttling valves. No separate pressurizing system was included; the tanks were simply left with an ullage space, which was then filled with gas to a few hundred psi. Because of the narrow tubing, the bulkheads between sections could be simple plates, instead of domes like virtually all other rocket stages. There was no ignition system; instead, a slug of furfuryl alcohol was injected before the kerosene. The furfuryl alcohol ignited spontaneously upon contact with the nitric acid.

The use of ablative cooling, high-pressure steel construction, and large "empty" spaces meant that a CRPU was heavy, with relatively low performance. The diameter of the tubing also put a hard limit on the engine diameter, preventing use of an efficient, high-expansion nozzle for the upper stages. However, ganging CRPUs into three stages was sufficient to reach orbit. Meanwhile, the low cost of each CRPU, after the economies of scale gained by producing hundreds or possibly thousands of them per year, would have still left the vehicle cheaper than its contemporaries. Additionally, the large number of small engines firing simultaneously would have given a high degree of reliability and a relatively smooth ride.

The company's baseline launcher design claimed to lift one metric ton to orbit. It would have consisted of a third stage core of four CRPUs, surrounded by a second stage of twelve CRPUs, in turn surrounded by the first stage's 48 CRPUs. Larger vehicles and capacities would be achieved with greater numbers of CRPUs, possibly including several hundred per flight for a heavy launcher.

The company forecast that CRPUs would eventually be so cheap, recovering and refurbishing a launcher would be no better than simply building more units. The use of storable propellants and few moving parts meant that launch-site operations would also be very simple. These advantages were expected to overcome the disadvantages of small specific impulse and payload fraction.

Flight History

The engines were tested extensively on ground rigs, on both German and African test sites. Experiments were run with varying fuel and oxidizer formulations, as the general design was quite robust.

Small, 4-unit vehicles were built and tested in Shaba North, Zaire and Seba Oasis, Libya, where heights of 20 to 50 kilometers were reached. The rockets used there were 6 and 12 meters long. The basic CRPU concept was shown to be workable, though some rockets experienced guidance or component failures. The last launch of an OTRAG rocket took place on September 19, 1983 in Esrange. Following this launch, the OTRAG rocket was to be used in high altitude research.

Political pressure then shut down the project, as discussed in the OTRAG article.

After the company had left Libya in 1987, some remaining equipment was confiscated by the government. However, enough parts and knowledge were missing to prevent Libya from continuing the project.

External links


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • OTRAG Rocket — The OTRAG rocket was a modular satellite delivery rocket developed by the OTRAG company. The OTRAG rocket was to become a rocket built up from several mass produced units, intended to carry satellites with a weight of 1 10 tons or more into orbit …   Wikipedia

  • OTRAG — Création 1975 Disparition 1987 Fondateurs Lutz Kayzer Personnages clés Kurt H. Debus …   Wikipédia en Français

  • OTRAG — For the rocket, see OTRAG (rocket). OTRAG (German: Orbital Transport und Raketen AG, or Orbital Transport and Rockets, Inc.), was a German company based in Stuttgart, which planned in the late 1970s and early 1980s to develop an alternative… …   Wikipedia

  • OTRAG-Rakete — Die OTRAG (Orbital Transport und Raketen Aktiengesellschaft) war eine deutsche Firma, die in den späten 1970er und frühen 1980er Jahren plante, ein alternatives Antriebssystem für Raketen zu entwickeln. Die OTRAG und der gleichnamige Flugkörper… …   Deutsch Wikipedia

  • OTRAG — Die OTRAG (Orbital Transport und Raketen Aktiengesellschaft) war eine deutsche Firma, die in den späten 1970er und frühen 1980er Jahren an einem alternativen Antriebssystem für Raketen arbeitete. Das Unternehmen und seine OTRAG Rakete gehören… …   Deutsch Wikipedia

  • Programme balistique zaïrois — OTRAG OTRAG Création 1975 Disparition 1987 …   Wikipédia en Français

  • RP-1 — (alternately, Rocket Propellant 1 or Refined Petroleum 1) is a highly refined form of kerosene outwardly similar to jet fuel, used as a rocket fuel. Although having a lower specific impulse than liquid hydrogen (LH2) and thus less thrust per unit …   Wikipedia

  • Single-stage-to-orbit — The VentureStar was a proposed SSTO spaceplane. A single stage to orbit (or SSTO) vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term usually, but not exclusively, refers… …   Wikipedia

  • Seba Oasis — Infobox Settlement official name =Seba other name = native name = nickname = settlement type = motto = imagesize = image caption = flag size = image seal size = image shield = shield size = image blank emblem = blank emblem type = blank emblem… …   Wikipedia

  • Private spaceflight — This article is about non governmental spaceflight. For paying space tourists, see Space tourism. For general commercial use of space, see Commercialization of space. Astronaut Dale A. Gardner holding a For Sale sign Private spaceflight is flight …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”