Propellant

“ A propellant may be considered as a substance that on explosion produces such a disturbance that neighbouring substances are thrown to some distance; a detonator or disruptor may produce an extremely violent disturbance within a limited area without projecting substances to any great distance. Time is an important, perhaps the most important, factor in this action. A propellant generally acts by burning in a more or less rapid and regular manner, producing from a comparatively small volume a large volume of gases ”

“ The term "duty involving the servicing of aircraft or missiles with highly toxic fuels or propellants" shall be construed to mean duty performed by members as a primary duty that requires (1) removal, replacement, and servicing of the emergency power unit of an aircraft with H-70 propellant (30 percent water, 70 percent hydrazine) ; (2) participation by those personnel performing duties in (g) (1) who must also participate in an emergency response force, spill containment, or spill cleanup involving H-70 propellant (30 percent water, 70 percent hydrazinc) ”

“ The composition of gunpowder, as regards the proportions of the ingredients, has not undergone any material alteration; the chemical proportions of the ancients being nearly those of the present day.
Gunpowder is an explosive propellant compound, consisting of saltpetre or nitre, charcoal, and sulphur. The terms, explosive and propellant, are not here used as synonymous—they are not convertible; for a chemical mixture may possess the explosive power in a much higher degree than the propellant: fulminating gold, silver, and mercury, are dreadfully explosive ”

“ For instance, the one which drives the shell from the gun, known as the propellant, must not be too sudden in its action. It must push steadily. Its purpose is to drive the shell not to burst the gun, wherefore its action must be comparatively slow and continuous so long as the shell is still in the gun. ”

“ The base of the shell is closed with a little disc of steel plate. People sometimes wonder why the original forging is not made solid at the bottom so as to save the necessity for this disc, but the reason is that if that were done defects might very possibly [Pg 144] arise in the steel in the centre which, since it is the very spot whereon the propellant acts, might let some of the heat or force of the propellant through, causing a premature explosion of the charge inside the gun itself instead of among the ranks of the enemy. ”

“ Many igniting compositions are examples of the last type, consisting of a high explosive diluted with a neutral substance, and frequently containing in addition a composition which is inflamed by the explosion of the diluted high explosive, the flame in turn igniting the actual propellant. ”

“ It is desired that a propellant shall produce the maximum velocity with the minimum pressure. The pressure should start gently so that the inertia of the projectile is overcome without any undue local strain on the breech near the powder chamber, and more especially that as more and more space is given to the gases by the movement of the projectile up the gun to the muzzle, gas should be produced with sufficient rapidity to keep the pressure nearly uniform or slightly increasing along the bore. ”

“ All three groups of engines are started and develop their full rated thrust while the missile is held on the launch pad. After takeoff, the booster engines burn out and are jettisoned. The sustainer engine continues to burn until its thrust is terminated. The swiveled vernier engines provide the final correction in velocity and missile attitude before they are also shut down.
The propellant tank is the basic structure of the forward or sustainer section of the Atlas. ”

“ Propellant pump rooms, located on silo level 8, contain fixed equipment used for transfer of propellants. Fuel or oxidizer unloading pumps and safety relief valves are installed in pump rooms to transfer propellants from missile tanks to holding trailers during normal transfer operations. Pump room indicators give direct indications of nitrogen pressure in missile tanks during transfer of propellants. Valves contained in pump rooms are used for isolation, draining, bypassing, bleeding, and venting various parts of the system. ”

“ This retro-rocket engine used a type of liquid propellant known as anhydrous hydrazine and it was so delicately controlled that it could burn for as little as 2/10 of a second and increase the velocity of the spacecraft from as little as 7/10 of a foot per second to as much as 200 feet per second. ”

“ No propellant is required to carry them to the target and no rifling is necessary to keep them head-on in the direction of flight. They are pulled instead of being pushed and can easily be kept in their course by means of rudder planes. But hitting a target from an aeroplane is like hitting a swiftly moving object from the ground. The target is seemingly flying past the aeroplane and in calculating where the aerial bomb will strike the [373] speed of the plane through the air and its height above the ground must all be taken into consideration. ”

“ Figure 20—MODERN GANNON POWDER. A powder grain has the characteristics of an explosive only when it is confined. Modern propellants are low explosives (that is, relatively slow burning) , but projectiles may be loaded with high explosive, a—Flake, b—Strip, c—Pellet, d—Single perforation, e—Standard, 7-perforation, f—Burning grain of 7-perforation type. Ideally, the powder grain should burn progressively, with continuously increasing surface, the grain being completely consumed by the time the projectile leaves the bore, g—Walsh grain. ”

“ Desirable Qualities.—Smokelessness is one only of the desirable properties of a propellant. All the present so-called smokeless powders produce a little fume or haze, mainly due to the condensation of the steam which forms one of the combustion products. There is often also a little vapour from the substances, such as oils, mineral jelly, vaseline or other hydrocarbon added for lubrication or to render the finished material pliable, &c. The gases produced should neither be very poisonous nor exert a corrosive action on metals, &c. ”

“ The propellants are then conditioned and transferred to the missile tanks where they are stored. Gaseous nitrogen is delivered to the launch complex in a tube trailer and transferred through hoses to the holding trailers or facilities systems to perform purging, and pressurizing operations. The missile propellant tanks are prepared for loading by pressure testing and purging the PTS; manually connecting the vent and fill-drain disconnects to the missile; leak checking the missile tanks; purging the missile fuel tanks ”

“ The roll control nozzle is connected to a hydraulic actuator installed between the missile and the roll control assembly. The flight control system receives guidance signals from the missile guidance set and sends control signals to the actuator. Pressurization of the Stage II oxidizer tank is not required in flght.. The Stage II fuel tank is pressurized by utilizing cooled exhaust gas.
AIRBORNE PROPELLANT SYSTEM The airborne propellant system (figure 1-55) consists of fuel and oxidizer tanks, disconnects, pressure transducers, storage valves, and pressurization and vent piping. ”

“ As soon as the blade of the propeller passes the barrel the system liberates the firing mechanism of the gun until another blade passes, or is about to pass, when the bullets that would pierce it are held up, just for that fraction of a second, again. So it goes on, like clockwork. You have noticed that on the new planes all the pilot has to do when he wants to fire his machine-gun is to press a small lever which is set, on most planes, in the handle of the directing lever. ”

“ In the case of the gun the gas is formed almost instantly and in such quantity that it has to drive the bullet out of the barrel to make room for itself. In the cartridge that our army uses, only about a tenth45 of an ounce of smokeless powder is used, but this builds up so heavy a pressure of gas that the bullet is sent speeding out of the gun at a rate of half a mile a second. It travels so fast that it will plow through four feet of solid wood before coming to a stop. ”

“ Instead, therefore, of the pressure falling rapidly, as the shot approaches the muzzle, the increasing quantity of gas tends to make up for the increasing space holding it. You will at once perceive that the slower the combustion of the powder the less difference there will be in the pressure exerted by the gas at the breech and at the muzzle, and the greater will be the advantage, in point of velocity, of lengthening the bore, and so keeping the shot under the influence of the pressure. ”

“ For, apart from the increase in the size and mass of the projectile and its greater initial resistance to motion, pressures tended to increase in a greater ratio than the size of the pieces themselves;205 the mass of the projectile increased as the cube, the propulsive force of the gases as the square, of the diameter of the bore; hence to attain a given velocity, the larger the bore the higher the pressure required to propel it with a given type of powder,—other things being equal. No limit, therefore, could be assigned to the strength and power required of heavy ordnance. ”

“ A shot produces its destructive effect either by its great weight or force of propulsion, or both combined. If the shot be light, the effects must come from force of propulsion. In any case great range is important. In throwing a shell, the chief effect of which is by the explosion of internal powder, the elevation at which it is fired is of little importance; but in battering ships, or breaching forts, shells are used to strike point blank as well as solid shot.
The armour used for covering vessels, consists of plates of iron or steel in as large sizes as possible. ”

“ The raillery is silenced by a deafening roar as the motors are tested. Quiet is briefly restored, only to be broken by a series of rapid explosions incidental to the trying out of machine guns. You loudly inquire at what altitude we are to meet above the field.
[144]
"Fifteen hundred metres—go ahead!" comes an answering yell.
"Essence et gaz! [Oil and gas!] " you call to your mechanician, adjusting your gasolene and air throttles while he grips the propeller.
"Contact!" he shrieks, and "Contact!" you reply. You snap on the switch, he spins the propeller, and the motor takes. ”

“ Of course, in order to keep the gas in there we have had to close up the touch-hole of the cannon, but now that we are ready to fire it, we will take this plug out, and touch a match to the gas. An explosion follows, and the bullet travels from the position “H” to the position “K.” All this time the crank of the grindstone must have been turning because the bullet and the crank are fastened together, and therefore, instead of traveling through the air, the bullet has used up its energy in turning the grindstone. When you get a grindstone started it is rather hard to stop, isn’t it? ”

“ Spotty trained his gun full in the centre of the quivering light rays that marked the circle of her whirling propeller, and poured burst after burst straight at the jerking flashes of the machine-gun that blazed through her propeller. ”

“ When burned in a cannon, all of the surfaces of the material are practically instantly ignited by a small flash charge of black rifle powder used for the purpose of setting fire to the charge of smokeless powder. The combustion in the perforations causes them to become larger and larger until the grain is all consumed. This form of grain tends better to maintain the pressure behind the projectile in its flight through the gun, and enables the use of larger charges of powder with lower pressures than could otherwise be employed. ”

“ If fine and quick-burning powder be used in a long barrel, the powder is flashed into propelling gas, instantaneously, and beyond a certain length of barrel has no further expansive power, and the result is a friction of the charge in escaping, that affects the shot and consequently the pattern on the target. If slow burning powder be employed in a short barrel, the whole of the powder cannot be so instantly flashed into the propelling gas and some portion of it is, as a result, driven unconsumed from the muzzle of the gun. ”

“ All who have witnessed the performance of the 80-ton gun must have been surprised at the mildness of its thunder. To avoid the strain resulting from quick combustion, the powder employed is composed of lumps far larger than those of the pebble-powder above referred to. In the long tube of the gun these lumps of solid matter gradually resolve themselves into gas, which on issuing from the muzzle imparts a kind of push to the air, instead of the sharp shock necessary to form the condensation of an intensely sonorous wave. ”

“ Damon. "If they had shot a few holes in the gas bag where would we be?"
"Right in the air," answered the balloonist. "It would take several volleys of bullets to damage our aluminum container. It is in sections and when one, or even five compartments, for that matter, are pierced, there is enough gas in the others to sustain us. So they could not have damaged us much, even if they had shot a lot of holes in us. Even without the gas container we can keep afloat by constantly moving, for the planes will serve their purpose. ”

“ While this is the feature of these powders which has attracted popular attention, a far more important quality which they possess is the power to impart to a projectile a much higher velocity than black powder does, without exerting an undue pressure on the gun. A velocity of over twenty-four hundred feet per second has been imparted to a one-hundred pound projectile with the powder that I have invented for our navy, while the pressure on the gun was less than fifteen tons to the square inch. ”

“ If this is true, we might as well let it clean the cannon. As the hole “I” is connected with the gas tank, we cannot let it force the burnt gas out there, can we? We will therefore pull out the plug “J” in the hole “E” just as the bullet reaches the point “K” so that in coming back it will force the burnt gases and smoke out through the hole “E.” Now we are all ready to start over again; the cannon has been cleaned out, and the bullet14 still being fastened to the grindstone, which is turning, as a result of the explosion, would immediately begin starting out on another outward stroke. ”