Aeronautics and astronautics – Aircraft control – Airship control
Reexamination Certificate
2001-11-26
2003-09-16
Poon, Peter M. (Department: 3643)
Aeronautics and astronautics
Aircraft control
Airship control
C244S030000
Reexamination Certificate
active
06619586
ABSTRACT:
FEDERALLY SPONSORED RESEARCH
Not Applicable
SEQUENCE LISTING OR PROGRAM
Not Applicable
BACKGROUND—FIELD OF THE INVENTION
This invention relates generally to the field of aviation, and more particularly to thermal airship buoyancy controller.
BACKGROUND—DESCRIPTION OF PRIOR ART
By virtue of a predetermined amount of lifting gas, traditional helium airships are “fixed” in terms of lift. Ascension and descension are accomplished with dynamic lift generated by changes in the pitch angle of the airfoil-shaped airship envelope and effected through the use of elevators.
Thermal airships derive lift by the means of heating the captive air within the airship hull. Ascension and descension are accomplished by changing the temperature of the captive air inside the airship envelope as a way of changing the value of lift desired rather than relying on dynamic generated lift. This process requires constant heat input to this captive medium to offset the radiant and convective losses incurred. The subsequent value of lift therefore, can inadvertently vary over time. Hot-air balloon burners are pilot operated and require a very acute and time-developed skill to achieve the desired flight control. Unintentional changes in pitch, and therefore dynamic generated lift, can confuse the airship pilot and cause erratic control. When additional airship control functions, such as engine throttle and rudder are added to this, the task becomes unmanageable for the airship pilot, and potentially dangerous.
When considering the thermal airship, it would be best to “fix” the difference between the internal air temperature of the envelope and the temperature of the air outside the airship envelope. This would eliminate the need for the airship pilot to constantly control the heat input necessary to maintain a thermal balance necessary for controlling the ascent or descent of the airship. Ascension and descension would be accomplished with dynamic lift through the use of elevators, therefore making the control similar to that of the helium airship.
With these requirements in mind, the inventor has designed a thermal airship buoyancy controller that “fixes” the difference between the internal air temperature of the airship envelope and the temperature of the outside air by using sensors to constantly sample the air both outside and inside the airship hull. This data is converted to a difference signal that is used as input for a process controller that manages the burner inputs. The pilot provides the processor with the desired difference temperature setpoint value and the processor constantly evaluates its performance and adjusts burn time to optimize the difference accuracy. The pilot, therefore, selects the desired amount of lift expressed as a difference temperature setpoint value, and the processor maintains this lift value automatically.
It has been found through the endeavors of the inventor and the patent search that there is no apparatus on the market and no apparent patents that have similar characteristics to the unique buoyancy controller devised by this inventor.
For example, U.S. Pat. No. 4,090,682 by Roger Parsons describes the use of a rudder and elevator system on a thermal airship and discloses that the pilot operated burner may be controlled “automatically” by a thermostatic sensor within the airship. However, there is no discussion of a closed loop control system that “fixes” the difference between the internal temperature of the envelope and the temperature of the outside air.
Also describing a very similar control system for a burner in a thermal airship, U.S. Pat. No. 4,087,239 by Douglas Obermoller discloses a thermocouple suspended within the envelope and a variable control of the fuel valve for the burner in order to maintain a predetermined temperature within the envelope. As with Parsons above, Obermoller does not disclose a closed loop control system that “fixes” the difference between the internal temperature of the envelope and the temperature of the outside air as does the applicant's invention.
No prior art teaches or suggests the particular novelty of the thermal airship buoyancy control processor of the present invention.
Objects and Advantages
In addition to the objects and advantages of the buoyancy control processor described in the above invention, several additional objects and advantages include:
(a) to provide a better system for burner operation for thermal airships;
(b) to provide a burner control system for thermal airships that reduces pilot demand and enhances overall control of the aircraft;
(c) to provide a burner control system for thermal airships that fixes the unit lift by fixing the difference temperature between the internal temperature of the airship envelope and the ambient temperature of the outside air;
(d) to provide a burner operating system that eliminates the pilot in the process of monitoring, maintaining and controlling the heat input to the airship envelope.
Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the invention, the thermal airship buoyancy controller comprises an airship envelope air temperature sensor, an ambient air temperature sensor, and a means of establishing a differential temperature value of the envelope air temperature and the ambient air temperature data. A means of comparison between the differential temperature value and an operator selected difference temperature setpoint value is made such that a means of adding heat to the airship envelope air is initiated, or a means of adding heat to the airship envelope air is suspended as a way of equalizing the comparison.
REFERENCES:
patent: 3798971 (1974-03-01), Lowrance
patent: 3957228 (1976-05-01), Kennedy, Jr.
patent: 4082239 (1978-04-01), Obermoller
patent: 4090682 (1978-05-01), Parsons
patent: 4591111 (1986-05-01), Laughter
patent: 4932606 (1990-06-01), Conn
patent: 5042748 (1991-08-01), Conn
patent: 6012675 (2000-01-01), Cocatre-Zilgien
patent: 6119979 (2000-09-01), Lee et al.
patent: 403197298 (1991-08-01), None
patent: WO88/0055 (1988-01-01), None
Collins Timothy D.
Poon Peter M.
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