US2431132A

US2431132A - System of propulsion

Info

Publication number: US2431132A
Application number: US489970A
Authority: US
Inventors: Frank J Malina; Summerfield Martin
Original assignee: Aerojet Engineering Corp
Current assignee: Aerojet Rocketdyne Inc
Priority date: 1943-06-07
Filing date: 1943-06-07
Publication date: 1947-11-18
Anticipated expiration: 1964-11-18

Description

1947 F. .J. MALINA ETAL 2,431,132

SYSTEM OFPROPULSION Filed Jflne '7, 1943 2 Sheets-Sheet l FOREBODY AFTERBODY 25\- 5 7.

MARTBN SUMMERFIELD FRAN K J. MAUNA INVENTORS.

Nov. 18-, 1947. F. J. MALINA ET AL w 2 A .1 Fm RL h EA w SM WM 2 RF A M n 7 v w 5 9 3 R 3 v I 3 E m 1 m a m w 5 D m. my 4 E vlA P e R O n A S F ull l O J s M 10 ll HEG 7 E n R w P Y m 5 4" INVENTORS.

BY A G T FIG. 2

Patented Nov. 18, 1947 NITED STATS ZAtLlBZ TENT OFFICE SYSTEM OF PROPULSION Delaware Application June '7,

4 Claims.

Our invention pertains to improvements in methods of jet propulsion and improvements in methods and apparatus for applying jet propulsion to waterborne Vehicles.

Our invention has particular utility in connection with the assisted take-off of airplanes such as seaplanes, flying boats and amphibious aircraft from the surfaces of water bodies and while our invention may be applied to other types of vehicles and to other types of aircraft, it will be described particularly in connection with flying boats because it finds particular utility in conunction therewith.

In their usual form, a flying boat comprises a hull the lower part of which is normally submerged in water. This lower part is separated by steps into a series of sections of successively shallower depth from bow to stern. In many flying boats, two such steps are utilized. The first or forward step divides the forebody from the after-body of the hull and the second step divides the after-body into forward and rear after-bodies. The first or forward step is generally blunt. The second step is generally pointed rearwardly, terminating in a keel.

In the conventional method of taking-oil a flying boat from the water, the propellers of the flying boat are driven by suitable power plant means and the thrust produced by the propellers accelerates the flying boat through the Water until the get-away or take-off speed is reached, at which point the flying boat leaves the water. The propellers produce a thrust which normally extends along an axis passing above the center of gravity of the flying boat. During the takeoff run changes occur in the trim (angular deviation of the longitudinal axis of the flyin boat from a horizontal plane) and the amount of water displaced by the airplane. Due to the combined effects of the trim changes and the changes in water displacement, the Water resistance producing drag on the airplane changes during the take-oil run. In normal operation the water resistance gradually increases for a time and then gradually decreases until it falls to zero at the get-away speed. The speed at which the dra due to water resistance reaches a maximum is known as the hump speed.

The steps in the hull of the flying boat normally render the average resistance during the take-off run lower than it would otherwise be if such steps were not present, and thus the steps facilitate take-01f.

According to the present invention a jet motor is used to improve the take-cit performance of a 1943, Serial No.'4i89,970

ber toward a common impingement point, and an exhaust nozzle in the Wall of the chamber through which fluids may be expelled into the surrounding medium under the influence of the heat of combustion generated by the reacting propellants. In the preferred form of our invention this jet motor is installed in the hull of a flying boat at a point beneath the water line thereof with its nozzle extending in a rearward direction. In its most practical form, the jet motor is installed in the substantially vertical wall of a step in the hull and beneath the water line.

Advantages of installing the jet motor beneath the water line of the hull are the following:

1. The combustion of the propellants is initiated smoothly and quietly even if the propellants are injected suddenly;

2. The exhaust gas blows water away from part of the hull surface, thus diminishing the Water resistance.

Such smooth initiation of jet motor operation is brought about by injecting propellants into the jet motor in spontaneously combustible relationship in the presence of water.

When a jet motor is installed in a step of a flying boat, which is normally submerged in water during at least part of the normal takeoff run, the expulsion of gas from the jet motor blows water away from the portion of the hull which is on the aft side of the step. By so blowing away the water the water resistance is reduced, probably partly because less water contacts the hull, thus decreasing the total surface tension acting on the hull and partly because the wavemaking resistance of the step is decreased. While we do not wish to be limited to any particular theoretical explanation of the action of an underwater jet motor in reducing water resistance, it is found that such reduction does occur and is advantageous. Thus with such an installation, the take-oil of a flying boat is assisted, not only because of the additional thrust provided by the jet motor, but also because of the diminished Water resistance.

In all installations of jet motors on flying boats, or similar craft, we prefer to orient the jet. motor in such a way that the thrust axis of the motor passes beneath the center of gravity of the flying boat. This tends to produce positive trimming moment which increases the angle of attack of the wing and thus assists the take-off of such aircraft.

With a jet motor installed on a flying boat in accordance with our invention, the time and distance required for the take-on run may be reduced or the gross weight which may be lifted into the air in a take-off run of normal distance may be appreciably increased.

One of the objects of our invention is to provide a system of jet propulsion which will improve the performance of waterborne vehicles. Another object of our invention is to provide a method for improving the operation of jet motors.

While only one specific application of our invention is described herein, from the description of our invention it will be clear to those skilled in the art that our method of operation of jet motors may be applied to other types of vehicles whether or not operating beneath the water and that other types and numbers of jet motors may be utilized in conjunction with waterborne vehicles, all in accordance with the principles of our invention set forth herein and within the scope of the appended claims.

Our invention will be more readily understood by reference to the following description taken in conjunction with the accompanying drawings wherein:

Figure 1 is a side elevation, partly schematic, of a flying boat with a jet motor installed in the first step thereof;

Figure 2 is a plan view, partly in section and partly schematic, of the jet motor system used to assist the propulsion of a flying boat shown in Fig. 1; and

Figure 3 is a side elevation, partly schematic, of a flying boat with a jet motor installed in the second step thereof.

In the drawing we have shown a flying boat 3 having a fore-body 5 and an after-body T separated by a forward vertical step 9, The fore-body 5 extends farther into the water than the afterbody 1. The forward step is formed by a vertical wall which extends across the lower portion of the hull beneath the water line I I. A second step I3 formed of a rearwardly tapered section terminating in a keel separates the after-body into a forward portion and a rear or tail portion, This ste is also beneath the water line of the flying boat in the particular flying boat shown.

The flying boat has a wing l5 mounted above the center of gravity I? in the fore-body. Propellers H] are mounted in front of the forward edge of the wing, and main power plants (not shown) are provided for rotating the propellers at the will of the pilot; The propellers have thrust axes XX parallel to the longitudinal axis of the airplane and passing above the center of gravity ll thereof. Means, such as pontoons I 8 supported from the Wings, are provided to assist in laterally stabilizing the flying boat while at rest or while moving at slow speed in the water. A tail assembly 2i is mounted at the aft end of the airplane. In the fore-body and in front of the propellers, there is a compartment 23 in which control instruments are mounted.

In the specific form of our invention illustrated in Figs. 1 and 2, a jet motor 25 is mounted in the wall of the forward step 9, The jet motor shown comprises a tubular body portion 2! terminated at one end by an injector 29 and at the other end a nozzle 31!. The nozzle 3! of the motor extends through the step and into the water. Any convenient mounting means such as brackets 33 are provided for supporting the motor rigidly from the floor of the hull. Suitable means 35 are provided for producing a watertight seal between the jet motor and the step wall.

Means are provided for injecting spontaneous- 1y combustible propellants into the jet motor chamber as impinging streams. Such means may comprise, for example, a pair of

propellant tanks

35 and 35" connected by

corresponding dispensing conduits

37 and 31 to corresponding injec= tion orifices in the injector 29 and means such as a tank 39 containing gas under high pressure operatively connected by suitable conduit means Al to said propellant tanks and adapted to force, or urge, propellants into the jet motor through said dispensing conduits. Valve means such as normally closed electro-magnetic valves 42' and 42" are connected in said dispensing conduits 31' and 31" respectively. Such valve means are adapted upon actuation to control the flow of propellants through said dispensing conduits in the jet motor. Such actuation is accomplished in the present instance by passing electric current through the solenoids 43' and 43" of said electro-magnetic valves 62' and 62" respectively, by closing a switch 45 in the control compartment, said switch being adapted to simultaneously connect a battery t! in series with both of said solenoids.

When the jet motor is not operating, water normally fills the motor up to at least the point of impingement of the propellant streams and preferably fills the motor substantially completely. When the switch 45 is closed, the propellant flow control valves E2 and 42 open and propellants flow as separate streams into the jet motor toward the common point of impingement. The rate at which propellants are injected is lessened somewhat by thepresence of water and the propellants are diluted by the water. Under these conditions spontaneous combustion of the propellants is retarded and the extension of combustion to propellant mixtures at points remote from the impingement point occurs gradually.

As the propellants burn, they generate gas at high pressure. Such high pressure gas expels the water from the combustion chamber. Thereafter, the impinging propellants mix, vaporize, and burn spontaneously substantially the same as they would if the jet motor operated at a point above the water line.

As the water which. initially filled the jet motor and the products of combustion, are expelled rearwardly from the nozzle, water (in which the flying boat has been floating) is blown away from the lower central surface 5' of the hull between the first and second steps.

The water resistance is reduced because water is blown away from said lower central hull portion 5' and also because of the fact that a positive trimming moment, that is the moment tending to nose the flying boat upward, is produced because the thrust axis of the jet motor passes beneath the center of gravity of the flying boat.

The jet motor may also be installed in the second step as shown in Fig. 3. Installation of the jet motor in this position has the advantage that because the under surface 5! on the bottom of the rear after-body is tapered rearwardly, gas may be exhausted from the motor in a relatively wide conical zone 52 without contacting the wall of the flying boat. Thus, as shown, the upper side of the conical zone passes adjacent the upwardly slanting under surface of the tail portion. With this arrangement exhaust fluids blow water away from the tail portion of the hull during the takeoff run and is especially eifective for this purpose when the trim is large, especially around the hump speed where the resistance and trim are at about their largest values.

If the jet motor is operated in either step while the propellers 19 are operating to take-off the flying boat the jet motor assists the propellers in accelerating the flying boat through the water and thus makes possible a shortening of the takeoff run or an increase in the gross weight or both.

From the foregoing explanation, it is clear that we have provided an improved method for assisting the take-011 of flying boats and that We have also provided an improved method for initiating operation of jet motors utilizing spontaneously combustible propellants. While our invention finds particular utility in the operation of waterborne vehicles, it is to be understood that our method of jet propulsion may also be applied to the operation of other vehicles within the scope of the appended claims.

We claim:

1. In a method of propelling a flying boat by the reaction of fluid exhausted through the nozzle of a jet motor mounted thereon, the improvement which comprises initially injecting concentrated nitric acid and aniline as impinging streams into the jet motor in the presence of water thereby gradually increasing the concentration of such acid and, aniline at the point of impingement until a spontaneously combustible mixture is obtained, utilizing the heat of combustion produced by the impinging streams to expel such water through the nozzle, and continuing the injection of such acid and aniline under spontaneously combustible conditions.

2. In a method of propelling a flying boat by the reaction of fluid exhausted through the nozzle of a jet motor mounted thereon, the improve ment which comprises initially injecting concentrated nitric acid and aniline as impinging streams into the jet motor in the presence of an inert solvent thereby gradually increasing the concentration of such acid and aniline at the point of impingement until a spontaneously combustible mixture is obtained, utilizing the heat of combustion produced by the impinging streams to expel such .solvent through the nozzle, and continuing the injection of such acid and aniline under spontaneously combustible conditions.

3. The method of raising a flying boat from the water which comprises submerging in the water a chamber mounted on the boat, said chamber 6 having a nozzle opening through which the water enters the chamber, separately injecting into the water in the chamber under pressure concentrated nitric acid and aniline so that the acid and aniline impinge against each other in the water in the chamber, thereby spontaneously combusting and driving out the water through the nozzle together with the gases of combustion, and continuing to impinge the acid and aniline against each other after the water has been driven from the chamber, until after the boat has risen from the water.

4. The method of raising a flying boat from the water which comprises injecting aniline and concentrated nitric acid separately into a chamber having a nozzle opening and attached to the boat beneath the water level and submerged in the water so that water enters the chamber through the-nozzle opening, spontaneously combusting the acid and aniline thereby driving out the water through the nozzle together with the gases of combustion, and continuing to inject the aniline and acid into the chamber for a, time after the water has been driven from the chamber, until after the boat has risen from the water.

FRANK J, MALINA. MARTIN SUMMERFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 866,330 Calkins Sept. 17, 1907 1,263,846 Brooke Apr. 23, 1918 1,283,684 Curtiss Nov. 5, 1918 1,375,601 Morize Apr. 19, 1921 1,501,568 Midgley July 15, 1924 1,571,862 Midgley Feb. 2, 1926 1,745,081 Crumbaugh Jan. 28, 1930 1,767,120 Canfield June 24, 1930 1,850,711 Fait Mar. 22, 1932 1,986,064 Leray Jan. 1, 1935 2,183,313 Goddard Dec. 12, 1939 2,217,649 Goddard Oct. 8, 1940 2,351,750 Fawkes June 20, 1944 FOREIGN PATENTS Number Country Date 17,696 Great Britain 1915 157,231 Switzerland Dec. 1, 1932