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aardvark2zz uploaded a new video
(2 weeks ago)
Maire Gérald Tremblay, Louise Harel, and Richard Bergeron
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I shook the hand of Maire Gérald Tremblay :-p ... and took vids and pics of Gérald Tremb...
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Maire Gérald Tremblay, Louise Harel, and Richard Bergeron
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I shook the hand of Maire Gérald Tremblay :-p ... and took vids and pics of Gérald Tremblay, Louise Harel, and Richard Bergeron :-O ... see pics and vids .... I even made a suggestion to Bergeron ...
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aardvark2zz favorited a video
(2 weeks ago)
@ NASA Langley Research Center
http://www.nasa.gov/centers/langley/h...
A scramjet (supersonic combustion ramjet) is a variation of a ramjet distingu...
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@ NASA Langley Research Center
http://www.nasa.gov/centers/langley/h...
A scramjet (supersonic combustion ramjet) is a variation of a ramjet distinguished by supersonic combustion. At higher speeds, it is necessary to combust supersonically to maximize the efficiency of the combustion process. Projections for the top speed of a scramjet engine (without additional oxidiser input) vary between Mach 12 and Mach 24 (orbital velocity). The X-30 research gave Mach 17 due to combustion rate issues. By way of contrast, the fastest conventional air-breathing, manned vehicles, such as the U.S. Air Force SR-71, achieve approximately Mach 3.4 and rockets from the Apollo Program achieved Mach 30+.
Like a ramjet, a scramjet essentially consists of a constricted tube through which inlet air is compressed by the high speed of the vehicle, a combustion chamber where fuel is combusted, and a nozzle through which the exhaust jet leaves at higher speed than the inlet air. Also like a ramjet, there are few or no moving parts. In particular, there is no high-speed turbine, as in a turbofan or turbojet engine, that is expensive to produce and can be a major point of failure.
A scramjet requires supersonic airflow through the engine, thus, similar to a ramjet, scramjets have a minimum functional speed, about Mach 7-8. Thus scramjets require acceleration to hypersonic speed via other means. A hybrid ramjet/scramjet would have a lower minimum functional Mach number, and some sources indicate the NASA X-43A research vehicle is a hybrid design. Recent tests of prototypes have used a booster rocket to obtain the necessary velocity. Air breathing engines should have significantly better specific impulse while within the atmosphere than rocket engines.
However, scramjets have weight and complexity issues that must be considered. While very short suborbital scramjet test flights have been successfully performed, perhaps significantly no flown scramjet has ever been successfully designed to survive a flight test. The viability of scramjet vehicles is hotly contested in aerospace and space vehicle circles, in part because many of the parameters which would eventually define the efficiency of such a vehicle remain uncertain. This has led to grandiose claims from both sides, which have been intensified by the large amount of funding involved in any hypersonic testing. Some notable aerospace gurus such as Henry Spencer and Jim Oberg have gone so far as calling orbital scramjets "the hardest way to reach orbit", or even 'scamjets' due to the extreme technical challenges involved. Major, well funded projects, like the X-30 were cancelled before producing any working hardware.
http://en.wikipedia.org/wiki/Scramjet
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aardvark2zz favorited a video
(2 weeks ago)
This video shows the startup of the VASIMR 1st stage over 5 seconds, the increasing power of the second stage over 3 seconds, a plateau of full pow...
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This video shows the startup of the VASIMR 1st stage over 5 seconds, the increasing power of the second stage over 3 seconds, a plateau of full power operation for 5 seconds, and then rocket shut down. The VX-200 is operating in a 150 cubic meter vacuum chamber, used to simulate the vacuum of space.
Ad Astra Rocket Companys VASIMR® VX-200 rocket prototype reached its highly-coveted 200 kW maximum power milestone at 11:59 am (CST) September 30th 2009 in tests conducted at the companys Houston laboratory. The DC power trace actually exceeded the design requirement by 1 kW and exhibited the clear signature of a well established plateau at peak power. The achievement comes after an intense experimental campaign that began in April 2009 when the engine was fitted with a powerful low temperature superconducting magnet, a critical component that enables VASIMR® to process large amounts of plasma power. The electrical power processing is accomplished using high efficiency, 95%, solid state RF generators built by Nautel Ltd of Halifax, Canada. Demonstration of a 200 kW capability was required to validate, with full scale performance data, the design of the VF-200-1 already underway. The VX-200 turns out to exceed the expected power density of VF-200-1 by about 25%, so this is a robust demonstration of the technology. The VF-200-1 is the first engine that the company plans to fly in space, and it is presently working with NASA to effectuate inspace testing in late 2013 on the International Space Station (ISS).
The total power processed by the engine is distributed between its two electromagnetic stages. The first, tested last July at its full 32 kW power rating, generates the plasma from Argon feedstock gas, while the second energizes it to the desired output conditions. At maximum power, the second stage contributes an additional 168 kW to complete the 200 kW power rating. The 200 kW test is, in effect, a validation of the VASIMR® second stage design, a hitherto untested element of the engine at these tremendous power levels, said Dr. Jared P. Squire, Ad Astras Director of Research and leader of the experimental team conducting the tests. Preliminary data indicate a better than expected power coupling, leading to slightly less thermal stress than originally predicted. These findings will continue to be verified, but the indications point to operation well within the chosen design specifications he said.
Short for Variable Specific Impulse Magnetoplasma Rocket, VASIMR® is a new high-power plasma-based space propulsion technology, initially studied by NASA and now being developed privately by Ad Astra. A VASIMR® engine could transport payloads in space far more efficiently and economically than todays chemical rockets. The company envisions an early commercial deployment of the technology, beginning in 2014, to greatly reduce the operational costs of maintaining an evolving space infrastructure, including space stations, satellites, lunar outposts and fuel depots in the Earth-Moon environment. Ultimately, VASIMR® engines could also greatly shorten robotic and human transit times for missions to Mars and beyond.
THE TECHNOLOGY
The VASIMR® engine works with plasma, a very hot gas, at temperatures close to the interior of the Sun. Plasmas are electrically charged fluids that can be heated to extreme temperatures by radio waves and controlled and guided by strong magnetic fields. The magnetic field also insulates any nearby structure, so temperatures well beyond the melting point of materials can be achieved and the resulting plasma can be harnessed to produce propulsion. In rocket propulsion, the higher the temperature of the exhaust gases, the higher their velocity and hence the higher their fuel efficiency. Plasma rockets feature exhaust velocities far above those achievable by their chemical cousins, so their fuel consumption is extremely low and their fuel-related costs substantially reduced.
ABOUT AD ASTRA
Ad Astra Rocket Company is a privately-owned corporation established January 14, 2005 to commercialize the technology of the VASIMR® engine, a plasma propulsion system originally studied by NASA with potential to support an emerging in-space transportation market. The company has its main laboratory and corporate headquarters at 141 W. Bay Area Boulevard in Webster, Texas, USA. Ad Astra also owns and operates Ad Astra Rocket Company, Costa Rica, a supporting research and development subsidiary in Guanacaste, Costa Rica.
www.AdAstraRocket.com
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