Dramatic Improvements Can Be Made in Spaceflight Safety

By Robert Talmage, Posted 12/15/09

2 comments

Aircraft Escape Cabin on Space Plane

Aircraft Escape Cabin on Space Plane


Robert Talmage, BSAE, is president of TAAS Company in Acworth, Georgia and our second "Guest" Author-Analyst. He has long been focused on the development of new escape systems and flight testing. His original proposal for a two stage rocket plane was published in Design News, Omni and Popular Mechanics. TAAS Company developed the Aircraft Escape Cabin (AEC) to offer a new option for crew recovery. Talmage recently presented the AEC technology and it’s value in flight testing and new space development at the AIAA International Space Plane Conference and AIAA Joint Propulsion Conference. His goal is to see these crew recovery techniques realized across multiple applications including military aircraft and spaceflight transportation.

Various NASA spokespersons, astronauts and managers are seeking a tenfold increase in flight safety standards for future astronauts. Several of their comments can be seen in “NASA Clamors for Safer Launchers”, by Todd Halvorson and published by Florida Today (November 29, 2009). Wayne Hale, NASA Deputy Administrator for Strategic Partnerships, went even further when speaking to the commercial space industry at the International Symposium for Personal and Commercial Spaceflight, (ISPCS) in October this year. Hale suggested that it was highly likely that NASA would require a crew escape system as part of any commercial services they would choose to procure for crew transportation.

Due to the launch dynamics, achieving greatly improved safety levels in vertical launch vehicles will inherently be far more difficult than for horizontal launch vehicles. Crew escape from a vertical launch failure imposes the most significant risks, weight penalties and technical complexities on a rescue system. For example, the Apollo Command Module (CM) carried three crew, at a total mass of 6000 kg. The recovery parachutes and equipment to land the CM on return to Earth weighed 250 kg or 4.2 % of the CM’s total mass. But the Launch Escape System (LES) add-on necessary to lift the CM away from a launch failure weighed 4200 kg. To protect the crew only during launch, the vertical launch Saturn vehicle had to carry the expendable and costly LES, adding weight penalties sixteen times that of the parachutes and recovery systems.

Use of aerodynamics in a horizontal launch vehicle eliminates the need for an escape tower (LES) by employing aircraft style flight safety characteristics. The other risks imposed by rocket propulsion, extreme speeds, very high altitudes and aerodynamic heating during the flight also warrant an escape system as has appropriately been indicated by NASA. Current escape technology for aircraft will not meet the requirements for space flight or accommodate multiple individuals. By satisfying these escape needs for a space plane, we can avoid the severe weight penalties associated with escape towers and fly individuals to space with aircraft style safety and efficiency. Vertical launch vehicles are best suited for un-manned operations.

An Aircraft Escape Cabin (AEC) system has been designed that represents the first new escape technology in a decade. The AEC enables escape and recovery at supersonic speeds and extreme altitudes. In an emergency, the AEC separates and glides to the most appropriate landing site on water or land. Equipped with light weight, simple mechanical devices and parachute technology, the AEC can provide safe recovery of occupants from most all in-flight emergencies.

The AEC’s modular features can also satisfy military crew survival needs and offer the cost-savings and versatility of interchangeable modular sections, such as crewed and un-crewed options. The primary markets for this modular technology are in commercial human spaceflight, military flight operations, and flight test vehicles. Flight research and testing precede the development of new aerospace vehicles; however, no  manned supersonic, high altitude, rocket powered, flight test vehicles are yet publically available. Targeting this emerging market with such a viable safety option satisfies an urgent need and offers a valuable service for the development of new vehicles and propulsion systems. A practical escape system would be especially important since space planes have the future goal to evolve from suborbital to the highly-desired orbital phases – a major technical challenge.

The simplicity of the AEC technique enables it to be adapted to an existing aircraft. The TAAS Company in Georgia, teaming with other aerospace companies, proposes to create a prototype AEC demonstrator. Since an AEC is relatively small, without propulsion or landing gear, the projected cost to fabricate and fly one is modest. The prototype demonstrator could subsequently be used with a rocket powered flight test vehicle for a full-up systems test (see above image).

New high speeds and altitude trajectories will soon change aviation as we know it. World transportation will shrink in time from double digits to two hours as global access becomes available. Eventually, with additional speed, crew and passengers will be flying to Earth orbit. Flight testing is the most urgent need for such development, and for this we need new escape technology.

Comments

Separation Dynamics

From: Robert Talmage, 12/29/09

Separation dynamics of the escape cabin will vary depending on the vehicle configuration and propulsion system. Typically, a horizontal launch would involve turbojet engines with aircraft style safety levels. This launch configuration eliminates the need for an escape tower. The ideal high speed propulsion for a space plane will be ramjets in the first stage and liquid rocket engines in the second stage. Both of these propulsion systems can be shutdown to eliminate vehicle acceleration and provide optimum escape dynamics. If a solid rocket or non-throttleable propulsion is used, a suitable rocket motor would be appropriate to accelerate the escape cabin from a failing vehicle. An escape cabin for an orbital space plane would have attitude control and de-orbiting rocket motors. These motors could also be used in emergency separation during other phases of flight. Aircraft style operation in space vehicles offers new levels of safety, efficient propulsion systems and economical re-usable vehicles. A practical escape system will mitigate the additional risks associated with space flight and high speed propulsion. Furthermore, development of these new escape techniques will spin-off to protect future military flight crews operating in hostile environments.

Separation motor

From: Anonymous, 12/28/09

The mass of an escape system derives from the desire to rapidly depart the vicinity of a failing vehicle while overcoming the pressure holding the capsule onto the high-speed rocket. The size of the escape rocket for an orbital vehicle does not depend strongly on whether it takes off vertically or horizontally. How do you propose to abort without a large motor to pull or push a cabin/capsule away at an acceleration of a few g?

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