US 3156092 A
Description (OCR text may contain errors)
Nov. 10, 1964 A. L. HOLZMAN 3,156,092 Q3 f HYBRID DEMONSTRATOR L/f/ Filed Aug. 9, 1962 INVENTOR: /JLzg/v #mz/MAN BYAMWM 7TH/@NETS United States Patent O 3,156,092 HYBRID DEMONSTRATGR Allen L. Holzman, Palo Alto, Calif., assignor to United Aircraft Corporation, a corporation of Delaware Filed Aug. 9, 1962, Ser. No. 215,840 1 Claim. (Cl. 60-35.6)
This invention relates to a demonstration model of a hybrid motor utilizing a novel fuel and control system. The unit is small so that it is easily transportable and utilizes a safe combustion system operating with safe propellants. It is completely restartable due to its selfcontained iginition system and the motor combustion can be viewed through the actual propellant fuel. It can be used as a laboratory tool for the evaluation of chamber configuration, oxidizer flow rate, grain length, grain composition and the like.
Generally speaking, the invention is carried out by providing a chamber of an oxidizable semi-transparent plastic such as Plexiglas (polymethylmethacrylate, also known as Lucite), polystyrene, polyethylene, Teflon, polybutyrate and the like. The plastic serves both as the actual fuel during operation and also as a transparent chamber so that one can watch the action of the hybrid motor. Plexiglas is ideal for this purpose since it serves as a typical hybrid fuel when used with oxygen, is clean-burning, and does not emit a carbonaceous exhaust. Further, it is a thermoplastic which is readily available as a molding powder as well as in rods and tubes, so that combustion chambers of any desired configuration can be fabricated without diiculty. Since oxygen and plastics are not hypergolic, an electric ignition system, as Well as means for providing a hydrocarbon fuel for starting, form part of the hybrid unit.
In the drawings forming part of this application:
FIGURE l shows a hybrid motor in section embodying the present invention.
FIGURE 2 is a schematic diagram of the control circuitry used in connection with the hybrid motor.
Referring now to the drawings by reference characters, there is shown in FIGURE 1 a hybrid motor generally designated 3 having a combustion chamber 5 fabricated of transparent plastic with a center burning port 7. Although the port 7 has been shown as a straight tube, other configurations might be used, such as an internal burning star and rods of combustible material which might be suspended within the port. At one end of the combustion zone, a nozzle 9, suitably of metal, is provided, while at the other end an ignition chamber 11, which may also be made of metal, is provided having a spark plug 13. An oxygen line 15 and a propane line 17 enter the ignition chamber 11 as is shown. An oxygen tank 19 which may have a valve 21 and a pressure regulator 23 provides oxygen in line 25 through a solenoid valve, 27. Similarly, propane is supplied from a tank 29 through valve 31 to the propane solenoid valve 33.
A suitable control circuit is shown in FIGURE 2, wherein the wires 35 and 37 lead to a source of electricity "ice such as an ordinary volt A.C. outlet. The circuit is fused as at 39 and the wires lead to a momentary contact switch 41 and to the oxygen solenoid 27. The wires also lead to a time delay relay 43 of the type wherein the contacts 45 and 47 remain closed only for a Short length of time, suitably 0.25 to 0.50 second after the relay is energized, and then open. The circuits formed by the wires 49 and 51 are thus energized only for a short length of time after current is first applied and during this short interval the propane control valve 33 and a step-up transformer 53 are activated. Suitable wires lead from the step-up transformer 53 to the spark plug 13. Indicator lights as at 55, 57 and 59 can be employed.
To operate the device, it is only necessary to close the switch 41 for the length of time for which it is desired to operate the motor. The oxygen valve 27 will remain open for the entire length of time that the switch 41 is closed, while the relay 43 will momentarily open the propane valve 33 and actuate the spark coil 53 for a short period of time to initiate burning. The propane and spark will then be automatically turned off and the motor will then operate utilizing only the plastic as a fuel and will continue to operate until the switch 41 is opened. The motor can be restarted any number of times merely by closing the switch 41 until the plastic fuel is consumed, whereupon it can be replaced and the operation started over.
Although propane has been given as a typical example of a suitable starting fuel, other volatile fuels such as naturalgas, ethane, buanekor the like can be used.
It is believdpparent from the foregoing that I have provided a safe yet effective hybrid demonstration unit which can be used as a research tool in exploring hybrid engine parameters.
A caseless hybrid rocket motor comprising a centrallyperforated, elongated propellant-grain of transparent, oxidizable plastic, said grain having sufficient web thickness to cause combustion to occur without rupture for a predetermined time, said grain having a forward end and an aft end, a nozzle connected to the aft end of said grain, means for storing fluid oxidizer, and means connected to the forward end of said grain for injecting said fluid oxidizer onto the surface of the grain perforation, said transparent grain serving to allow visual observation of the combustion phenomenon.
References Cited by the Examiner UNITED STATES PATENTS 1,958,773 5/34 Stuart 158-28 2,519,889 8/50 Crawford 158-28 2,632,294 3/53 Wall 60-35.6 2,771,741 ll/56 Barnard 60-3946 2,791,883 5/57 Moore et al. 60--35.6 2,990,682 7/61 Mullaney 60-35.6
SAMUEL LEVINE, Primary Examiner.