Power plants – Reaction motor – Method of operation
Reexamination Certificate
2002-05-22
2003-03-11
Gartenberg, Ehud (Department: 3746)
Power plants
Reaction motor
Method of operation
C060S240000, C060S223000
Reexamination Certificate
active
06530213
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to ignition systems and, more particularly, to an ignition detection system for use prior to and/or during a lift-off/take-off sequence of a rocket powered spacecraft/aircraft.
BACKGROUND OF THE INVENTION
Propulsion systems and/or rocket engines have traditionally been utilized in a variety of applications ranging from space shuttle and rocket missions to missile launching applications. These propulsion systems and/or rocket engines ideally possess safe and dependable systems for controlling their ignitions and accompanying launches. In particular, safe and reliable engine ignition is particularly important in spacecraft applications involving the launch of manned spacecrafts such as liquid fueled rockets and space shuttles.
These propulsion systems and/or rocket engines generally have a combustion chamber that releases an exhaust plume from the exhaust nozzle(s) of each engine. These exhaust plumes generally include heat and flames, among other distinguishing features. A failure to properly ignite the fuel utilized for providing a pilot light and/or the main fuel in the combustion chamber may result in one or more engines malfunctioning and the spacecraft lacking the lift needed for launch, potentially resulting in the loss of lives and/or damage to the spacecraft and/or launch pad. Further, an incorrect or failed ignition may be symptomatic of one or both fuel and oxidizer from the spacecraft being dumped onto the launch pad. Any subsequent ignition of this fuel/oxidizer could potentially result in a catastrophic event.
One conventional procedure of engine ignition detection includes stretching wires across each engine exhaust nozzle. The plume of exhaust is intended to burn away and generally completely sever each of the wires, thus indicating that each of the engines are sufficiently ignited. Potential problems with this type of an ignition detection system include, but are not limited to, wind breaking the wires that span across the exhaust nozzle(s) indicating successful ignition before launch is even attempted. This would yield a potentially “false positive” signal if ignition did not in fact occur. This type of ignition detection system can also result in “false abort” signals as well. That is, there may be instances where even a proper ignition may fail to completely burn through or otherwise sever the wires. This false “failed” ignition signal can cause the launch of an entirely satisfactory rocket to be aborted.
SUMMARY OF THE INVENTION
The present invention is generally directed to the detection of engine ignition. More specifically, the methods and apparatus of the present invention are generally directed to the detection of liquid-fueled rocket engine ignition of a spacecraft/aircraft. A preferred application of the present invention may be in the use of ignition detection systems for launch vehicles.
A first aspect of the present invention is embodied in a method for operating an engine (e.g., a liquid-fueled rocket engine). The method generally includes initiating an ignition sequence that includes at least a first ignition stage and a second ignition stage for the engine. The method further includes monitoring first ignition stage electromagnetic spectra and second ignition stage electromagnetic spectra at least during a time corresponding with the first and second ignition stages, respectively. A first relay is generally activated if the first ignition stage electromagnetic spectra reach(es) a first predetermined threshold within a first predetermined timeframe. Correspondingly, a second relay is generally activated if the second ignition stage electromagnetic spectra reach(es) a second predetermined threshold within a second predetermined timeframe. “Reaches”, in relation to the first and second predetermined thresholds, encompasses meeting a certain value, exceeding a certain value, or both. In the event that either relay is not activated within the corresponding predetermined timeframe, the ignition sequence is generally terminated.
Various refinements exist of the features noted in relation to the subject first aspect of the present invention. Further features may also be incorporated in the subject first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the first ignition stage electromagnetic spectra may include ultraviolet, visible, and/or infrared light rays but may be most intense in the visible. Accordingly, this first aspect may include monitoring electromagnetic spectra within a wavelength range of about 400 nm (visible blue light) to about 700 nm (visible red light). The first ignition stage electromagnetic spectra may thereby encompass a range of wavelengths, although the first ignition stage electromagnetic spectra may also be a single, individual wavelength. The second ignition stage electromagnetic spectra may include ultraviolet, visible, and/or infrared light rays but may be most intense in the infrared. Thus, this first aspect of the present invention may include monitoring electromagnetic spectra within a wavelength range of about 7.0×10
2
nm up to about 3.0×10
5
nm, and in some embodiments, a wavelength range of anywhere between 7.0×10
2
nm and 7.8×10
2
nm up to about 1.0×10
5
nm. As with the first ignition stage electromagnetic spectra, this second ignition stage electromagnetic spectra may also encompass a range of wavelengths or may merely include a single, individual wavelength.
Generally, one or both of the first and second ignition stage electromagnetic spectra in the case of the first aspect may be emitted by an ignition of at least one of hypergolic fuel and kerosene. In one embodiment, a mixture of hypergolic fuel and liquid oxygen is utilized in the first ignition stage, while a mixture of liquid oxygen and kerosene is utilized in the second ignition stage. In this case, the first ignition stage electromagnetic spectra may be visible electromagnetic spectra that are monitored for purposes of the first ignition stage, while the second ignition stage electromagnetic spectra may be infrared electromagnetic spectra that are monitored for purposes of the second ignition stage. “Hypergol” (also known as hypergolic fuel) refers to a liquid fuel or propellant that generally ignites in a substantially spontaneous fashion upon contact with an oxidizer. An “oxidizer” generally includes oxygen and/or any compound that spontaneously evolves oxygen either at ambient temperature and/or upon exposure to heat. These oxidizers (or oxidizing materials) generally react vigorously (i.e., can cause and/or support ignition/combustion) when mixed with reducing materials (such as liquid hydrocarbons, hypergolic fuels, cellulose-based organic compounds, and/or other appropriate organic compounds).
First and second ignition stage electromagnetic spectra that generally are associated with the first and second ignition stages of the ignition sequence may be monitored in this first aspect of the invention. In this first aspect, the process of monitoring electromagnetic spectra can include using spectrometers, radiometers, and the like, some of which may optionally be equipped with filters. In one embodiment of the first aspect, photons of the first and second ignition stage electromagnetic spectra are converted to electrical signals (i.e., photo-electrons), and these electrical signals are then monitored for the first and second predetermined thresholds (e.g., first and second voltage thresholds, respectively) as well as if/when in the timeframe of the launch sequence these thresholds are reached. These electrical signals may be amplified (e.g., using an appropriate amplifier) to improve one or more aspects associated with the monitoring of the same to identify the existence of first and and/or second ignition stage electromagnetic spectra that reach the corresponding predetermined thresholds.
As previously mentioned, the first relay can be activated upon the first ign
Anderson Scot K.
Beck Philip
Klein Gerald P.
Scheld Daniel L.
Thielman Donald J.
Gartenberg Ehud
Lockheed Martin Corporation
Marsh & Fischmann & Breyfogle LLP
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