US2507878A - Projectile - Google Patents

Description

May 16, 1950 T. A. BANNING, JR

PROJECTILE 5 Sheets-Sheet 1 Filed Oct. 16, 1943 May 16, 1950 T. A. BANNING, JR

PROJECTILE 3 Sheets-Sheet 3 Filed Oct. 16, 1943 InvenTor': ,TPIomo 75cm n i n Patented May 16, 1950 4 Claims.

The present invention concerns itself with improvements in ordnance. The features herein disclosed are adapted for use in ordnance of various sizes and calibers; and also in ordnance of various types, such as cannon, howitzers, mortars, and the like.

The-features of the'present invention are also applicable to use with projectiles of either the solid shot type or the-shell, shrapnel, or other types; andwith either fixed or separate loading ammunition.

One principal feature of the present invention concernsitself with means and methods for re-- cover-ingfrom the propellantcharge a large portion of the energy of combustion and explosion which has heretofore been wasted, and transferring such recovered energy to the projectile in the form of greatly increased muzzle energy in the form'of increased muzzle-velocity; or conversely, making it possible todeliver to the projectile a desired or specified amount of muzzle energy or velocity with consumption of a greatly reduced propellant charge; or a combination of both of these results.

A further feature of the invention concerns itself with means and methods for. delivering to the projectile the desired rotative energy in the form of revolutions per second at exit from the muzzle, with a shortened rifiing (or no rining) thereby making it possible to materially reduce the cost of 'the gun construction and also materially reducing wear and deteriorationvof the gun lining in service.

since the acceleration of the'projectile during its flight down the bore of the gun (in previous arrangements) has been due to the pressure of the gases against the base of the projectile, it has heretofore been desirable to maintain said gas pressure-relatively high up to the instant. of exit of the projectile from. the muzzle, in. order to deliver the desired. total muzzle energy to the projectile with a not too long barrel. Therate of combustion of. the propellant has accordingly been adjusted to an amount which will maintain the desired pressure of the propellant gases.

Due to the relatively high gas pressure at termination of the projectile flight it has heretofore been the case that the energy remaining in the gases at'the' instant of exit of the projectile has been very high, constituting. a very large proportion of the. total energy of combustion of the propellant. Heretofore this energy has been completely wasted,- and has appeared as noise of the explosion, and heat of the exiting gases,- aswell as other factors or waste to be hereinafter considered. Conversely,'the total muzzle energy of the projectile at instant of 'exit from the muzzle has been only a small proportion of the total energy of combustion; so that the mechanical eflicienc'y of-th'e machine has been very small.

A principal object of the present invention relates to means andmethods whereby a large part of" this heretofore wasted energy maybe recovered inthe form of" additional muzzle energy ofthe projectile; or so that conversely, the amount of propellant neede'dto deliver a given totalmuzzle energy to :the projectile may be" materially reduced. In order that certainfeatures ofth'e invention-.may-be better understood, and their significance be 'better appreciated I shallnext showgenerally the-distribution of the energy of combustion of the propellant in a typical case, without use of the features of the present invention-;-- and I shall thendiscuss those portions of the energy" whichmay be recovered by use of-fe'atures of the-present invention, and shall show how the-distribution of the'energy in the-barrel during projectile flight may also be improved.

In a typical case of athreein'ch gun, the followingass'ump'tions: are made; weight of projectile, 1-5# weight of propellant, 4-.8'74# of decanitrocellulose with 6 moisture and volatiles, and .4-% stabilizer (giving 1,266,000 ft./lbs. per pound); travel of projectile to muzzle 139.89; weight of gun, l950#; average friction ofbands on gun bore, 5898-# sq./in. on base of projectile; muzzle velocity (withoutmy improvements) 2600 ft./secs;-; rifling (without my improvements) 1/40 calibers; total volume of chamber plus barrel, .78 cu. ft. chamber capacity, 296 cu. in.; density of loading .4558.

'With theforegoing; and without the improvements=ofmy pr's'enti-nvention the following generalresults are found;

Combustion is complete at about 41" projectile travel; maximum gas pressure, 36;000#' sq./in.; maximum gas temperature, 3451 degrees above zero (2.; total available energy of combustion, 2'75e168-ft. tons; gas pressure at muzzle (instant of exit of projectile), l3 ,750# sq./in.;= temperature atmuzzle (instant of exit of projectile), 2555.7 degrees-above zero C.; adiabatic expansion commences after projectile travel of about 41"; total muzzle energ of projectile, 703.7 ft. tons. Since'the total energy of combustion of the propellant was shown to be 2754.68 ft. tons it is evident that there is a direct dead loss of 2650.98 ft.tons'(2754=.68+703;7-); or, in other Words, the inechanicalefficiency of the gun a a machine is 3 only 25.545% (being 703.7 divided by 2754.68). In this assumed case, also, the total muzzle energy of the projectile comprises 702.41 ft. tons translation energy and 1.29 ft. tons rotative energy, the R. P. M. at exit being approximately 15,600.

Manifestly, a large portion of this non-useful energy is in the form of heat and in other forms which may not be recovered; and in order to determine what portion thereof may be available for more efficient conversion to projectile energy I have made the following analysis:

The energy of the gases is expended in accelerating the projectile (both translation and rotative energy) in heating the parts with which the gas is in contact (principally the gun barrel), and this is a dead non-recoverable loss; in the form of friction of the projectile during its flight down the barrel, which energy also appears as heat, but is herein treated as a separate item of distribution, and which friction is chiefly due to engagement of the projectile bands with the lands of the rifiing, and a portion of this energy item may be recovered if means be found to ensure the desired rapidity of rotation of the projectile with a shortening or elimination of the rifling; in the form of energy of recoil of the gun, carriage, etc., and this is a dead non-recoverable loss; and in the form of energy of velocity of the gases following the projectile down the barrel during its flight, and a portion of this energy is recoverable, as we shall presently see. Therefore, of the several items above listed we find that the energy of heating the barrel, etc. (not including friction loss), is a dead loss, the energy of recoil is a dead loss; but that the energy of friction may be partially saved, and the energy of gas velocity may also be partially saved.

Calculations in the assumed case show the following: Heat loss (non-recoverable), 216.95 ft. tons; friction loss (partially recoverable, possibly fully recoverable), 216.95 ft. tons; recoil loss (non-recoverable), 7.32 ft. tons; energy of velocity of gases following projectile down barrel (partially recoverable), 76.14 ft. tons. These several items, both recoverable or partially recoverable, and non-recoverable, add up to 517.36 ft. tons, of which 224.27 ft. tons are non-recoverable, and 293.09 ft. tons are at least partially recoverable.

If now, we subtract this amount of 517.36 ft. tons from the amount of 2050.98 ft. tons, previously found to be the total non-used energy, we find the difference to be 1533.62 ft. tons, and this item represents energy contained in the exiting gases at the instant of exit of the projectile from the muzzle, in addition to the energy of velocity of the gases following the projectile down the bore. If we add to this item of 1533.62 ft. tons, the amount of 76.14 ft. tons (velocity energy of the gases) we get the total amount of 1609.76 ft. tons, as representing energy all or a portion of which may be recoverable, and which amount is in addition to the muzzle energy of the projectile itself (according to previously known and used arrangements and methods) plus the dead, non-recoverable losses. In other words, my invention concerns itself with means and methods for recovering all or a portion of this amount of 1609.76 ft. tons, in the assumed case of a three inch gun and projectile, and transferring such recovered energy to the projectile in the form of added muzzle energy. Such amount of 1609.76 ft. tons comprises 58.437% of the total energy of the propellant powder,

4 so it is very evident that a substantial saving of this great loss is very much to be desired.

This energy of the exiting gases (1609.76 ft. tons in the assumed case), includes 0., energy of compression of the fixed or perfect gases; b, energy of temperature of the gases at instant of exit; 0, latent heat of evaporation of such vapors as H2O, etc.; and d, the energy of velocity of the gases following the projectile down the bore. In the assumed case of the deca-nitrocellulose propellant, the terminal products comprise CO2, 2.73436#; (30, 1.24287#; H2O, 0.15977#; H2, 0.11546#; and N2, 0.62154# (totaling to 4.874#) and these amounts of these several products will give the following free volumes at sea-level pressure and 32 degrees F., namely; CO2, 22.156 cu. ft; CO, 15.920 cu. ft; H2O, 2.890 cu. ft; H2, 20.541 cu. ft.; and N2, 7.961 cu. ft. These products therefore will total 69.468 cu. it. free volume at sea-level pressure and 32 degrees F. Yet it will be remembered that the total assumed volume of the chamber and barrel of the gun was only .780 cu. it, so there has been a very large and almost instantaneous expansion of the products at the instant of exit of the projectile from the muzzle.

Now, as a matter of fact the gas temperature and pressure at the muzzle condition and just prior to exit and reduction of pressure, is, as previously shown, 2555.7 degrees 0. (above zero, or 2828.7 degrees abs. and 13,750 lbs/sq. in). If this gas be expanded to sea-level pressure from the temperature and pressure just above stated, under adiabatic conditions, and assuming Ic=1.4 (where and when lc for CO2 equals 1.229; lc for CO equals 1,405; k for H2O equals 1.299; 10 for H2 equals 1.404; and k for N2 equals 1.407), then equals 3.5; and we find that, for the assumed adiabatic expansion the terminal temperature at sea-level pressure will be 127.58 degrees C. above zero, or 261.6 degrees F. above zero. Using the formula PV=RT, we find that R=3.7406; and the volume at the terminal temperature and sea-level pressure is found to be 101.96 cu. ft. (the terminal temperature being, as just above shown, 261.6 degrees F. above zero), instead of 69.468 cu. ft. for the assumption of 32 degrees F., as heretofore stated.

Now the work to press back the surrounding atmosphere (at sea-level pressure), from the volume of .780 cu. ft. to the final volume of 101.96 cu. ft., is equal to 214,135 ft. lbs., or 95.69 ft. tons. Also, the temperature of these expanded gases is, as above stated, 261.6 degrees F., instead of 32 degrees F. (to which base the total energy of combustion of the propellant is referred); so we must determine the mechanical equivalent of the heat necessary to raise the gases of combustion from 32 to 261.6 degrees F. The weights of the gases have already been stated. The specific heats of these gases may be assumed as follows (same being at constant pressure); CO2, 0.187; CC), 0.245; H2, 3.410; N2, 0.243; and H20, 0.480. Upon making the determination we find that the energy thus accounted for is, 114.54 ft. tons.

Now it was shown that the energy at the muzzle, all or a portion of which is recoverable, amounts to 1609.76 ft. tons. From this we mustdeduct asornsrle amountiof; 195169 .it; :tons; representing the energyitoyexpand thezgases'zagainst the pressure of; the; atmosphere; and; also must: deduct the amountoi: 114 .54: it. tons, representing the nonavailable vheat :-energy.'at completion ;of: such .expansion. These-twoideductions amount to 210.23 it; tons; v.which deducted from-the; amount of IGOQHGSIBEVBS 1399,53tft. tons; or 50.805% of' the totallenergy of combustion. In other words, We lrave'a pool of slightly more. thanufiity percent ofi the totaLenergyrof combustion which isat present being wastedai. but which is. in. the storm otener yg some at'leasti of-which is recoverable toLincrease :the. muzzlezenergy of v the projectile; or cconversely, byfiimprovements \presentlycto be disclosed herein, we may either increase the muzzle. energy otthe projectile for a. given expenditure. of propellant; or may secure the samemuzzlevenergy as heretofore with'lexpenditure of as lessamount; ofr: propellant;

It is also:here notedthat under the assumed conditions the muzzle: energy heretofore being securedcamounts to-only 25.545% of the total energylofacombustion, and that the-pool of additional energy, at least aportion ofwhich isavail able. by useof my present. improvements, amount to 50.805% of the-totalenergy oflcombustion; so that ifiwewwereableito translate all'this heretofore-Wasted but=available energy into additional muzzle :energywea shouldlbeable to increase the muzzle energy 'tothe amount.of-76.350% of the total, (25545 plus 50.805), or substantially three times as much as heretofore, 'making the gun three times. as eificient as heretofore. Even if wecouldidouble the muzzle energy or the effim'ency ofctheugun weshould have a very substanin'alimprovement. I shall presently show how the features of my present invention will serve touveryxgreatly improve the operation and emoiency of the gun.

In the-above analysis the item of friction of theprojectile on the -wall ofi theba-rrel during flight was shown tmamount-to 216 .95 ft. tons, and this-item was stated to-be-partially recoverable, possibly fully recoverable. This item representsprincipallythe friction-of the bandson thelands of the rifiing, and-ithasbeen an item; which: heretofore has-been largely unavoidablecdueto the-need of using rifiing for producing all the rotary or spinning motion of the exiting projectile; I shall presently show, as one feature of lily-present invention, how the rotary motion of theprojectile may be largely produced (if not entirely produced) by the reaction, of the gase themselves; so that at least a portion of this. wasted energy maybe, recovered; and used. Inthe illustrationwhich I shall presently enlarge herein of one application'ofv thec-featuresofmy present invention .II'have assumed a discontinuance ofr'therifiing. after a flight of about 84" down. the barrel, at which time the projectile has been'acceleratedito.13,2003R; P. M;, and there-- maining: rotative energy to--bring the projectile up to:l5,600'R. P. Maissuppliedtoth'e projectilebyhth'e ireactiomofithe gases. according to one feature: of; my: present. invention." By suchshorteningfofthe rifling 1 am able itogreatly reduce-theirictioncloss?for.-a-portiorrof'thefiightv The energy saving thusgefiected amounts to 73:8691ftntons, which energy isdirectly available to increase the muzzle velocity of the projectile; so t-that: with such: shortened rifiingn the-muzzle velocity .is increasedsto. 27-35. lit/secs. instead; of: the 2600 originally assumed foz' -the gun in ques'-- tiers; and; fiirc'whiclrithepresent analysis isl-Ibeing s madev ThiSilS la; =directxirrcreases of; 110349757; as compared with the" original JmU-ZZIG'. energy. or 703.7 f t; tonsiffors theprojectile:

The available energy, 1399.53,. .ft. tons, 4above. referred tolisazreleasediatithe moment of exit of the projectile-fromthe muzzle; and appears as disturbance, chiefly: in the .formc of noise and shattering of; the surrounding :air into which the gases are discharged At the ihstantjust prior: to this :release .ofc'th'ese gasesthey wereiconta-inedl within the barrel under a1 pressure- 0f: 13,750it sq./in., and at atemperature .of:'i2555.7 degrees-C. above zero (notabsi'). Maniiestlyuif.these gasescould be so. handledzas to beaallowed toiexpanda Y under conditionssuch thattheir energy 'could" be converted into usefuliworktransferred tothe projectile; a very. great improvement in theoperation of the machinecould be effected. Much of: the energy. of expansion of these' gases-as here tofore released '(it; not'iall such energy) is trans ferred into the form. of ga velocity of some sort, but is not or has not been .controlledbuseiully, I propose to make such control, and to thereby deliver alarg-e:part :of this energy: to r the pro jectiie before such projectile passesitoo far away from the gun muzzle.

I propose to so arran'gethe parts of the projectile, that the energy of 'expansion of these, gases uponreleasemay-be-.efiective1y"used forreaction against the bas'e and/or other-=portions of the projectile, that-a considerable portion 0'1- the energy maybeconverted into usetul work of projectile velocity, If we consider the gun'barrel as a nozzlewhich issuddenly-opened upon the exiting of the'projectilethe gases-thus releasedwill exert a certainpressure against the base portion of the projectile until said projectile has passed away so far-that such action no longer is effective. This pressure will I consistof two components; that of static pressureagainst the-- projectile base, and thatof velocity-or dynamicpressure due to the velocity at which the particles of gas are impingingagainst the projectile base.

The former component -will veryrapidly fall to zero, dueto the very rapid' drop'of-gasapressure as soon as the muzzle=ofithe gun has been openedbyexit of the projectile;- and 'likewisethe-latter orof the gases in thebar-rel hasbeen effective to accelerate the -projectileduring its flight down the bore of the barrel, and the dynamic energy of the gasesdue to-their velocities, especially at the moment of release-has been-completely lost asfar as any effectiveprojectileenergy is concerned;

I propose to provide means and methods for recovering a large portion-ofthis dynamic energy in the form of added projectile energy, delivered" to the projectile duringand -adja'centto the exit ing of the projectilefrom'the muzzle.

ing gases during the interval 'ofrelease of said-- gases from the high pressure which the still suffered at and during-the interval of release,

and is completely supplemental to-the-delivery of energy to .theprojectil'e -by statiepressure on thecprojectilelsibaseo- Such recovered energy is delivered to the projectile principally by reason'of the reaction-oithe exit- It is well understood and known that a gas undergoing'reductionof pressure, as in a jet or orifice exerts a reaction on. the body from which it is being released; and also that in case of impingement of a jet of such gas against another body there is created a reaction on said body. Furthermore, a reaction is created in the case of a stream of gas undergoing violent change of direction, as in the case of a jet of gas impinging against a bucketso formed as to completely or largely reverse the direction of flow of the gas of such jet. In the case of a complete reversal of direction of the. gas of a jet impinging against a properly formed or shaped bucket, or in the case of complete reversal of direction of flow of a stream of gas just prior to its exit from a jet, there will be produced a reaction substantially double the amount of the static pressure of the gas against the area against which it may be pressing, so that by the use of such reversal of direction we may secure very large reactions; and by properly arranging the parts we may direct such reactions effectively against the projectile itself, with consequent great benefits in the form of energy transferred to the projectile.

Sometimes I so form the base portion of the projectile itself that the gases exiting from the muzzle will react against the base of the projectile and have their direction reversed, thereby exerting a very, large reaction against the base of the projectile, and adding a substantial proportion of energy to the projectile after the projectile has actually passed clear of the muzzle. In other cases I so form the projectile that the gases flow through a portion of the projectile (or an extension thereof) and then through the original exiting orifices, so that during the original portion of the gas releasing interval the gas release actually takes place through orifices constituting a. portion of the projectile itself, or an extension thereof.

Since the reaction principle is used, it is possible to so arrange the parts that said reaction (due to dynamic conditions) will be either straight ahead against the projectile, or so that said reaction may also include a rotary component tending to promote the rotation of the projectile, either during its movement prior to complete exit from the muzzle or immediately thereafter. In either case such rotary force will add to the rate of projectile rotation, and thereby the work to be performed by the rifling of the barrel may be either completely eliminated (with complete elimination of the rifiing) or partially eliminated (with corresponding reduction of the work to be performed by the rifiing). In either case the muzzle velocity and muzzle energy of the projectile will be correspondingly increased (under the assumed pressures within the barrel) so that corresponding improvement and increase of efiiciency of the operation will be secured.

The reformation or redesign of the base portion of the projectile to secure the desired reversals of gas direction may be effected substantially without material change of the overall dimensions of the projectile itself; and furthermore, it is possible to make these changes in projectiles of various shapes and sizes, including so-called boat-tailed projectiles and others. In some cases it may be desirable to increase the interval of time during which the reaction during release of gas pressure is being availed of, so as to greatly increase the energy recovery.

This may be. accomplished by provision of gas passages in the tail portion of the projectile itself, through which passages the gases flow to the orifices for reaction release, Sometimes these passages may beprovided as a permanent extension to the base portion of the projectile, with consequentincrease of projectile length. In other cases I provide arrangements such that a portion of such extension (or all of it) may collapse forwardly overthe body of the projectile after leaving the muzzle and during the early stages of free flight, thereby securing the benefits of my improvements without the disadvantages, if any, of the increase of projectile length. In other cases I provide combined arrangements.

1 When such a collapsible arrangement as just referred to is used, the telescoping or collapsing portion of the projectile may move forward over the body of the projectile during free flight. Such movement will be secured by reason of the deceleration of, the projectile with consequent tendency of such telescoping portion to slide forwardly over the body of the projectile, so that after a relatively short interval of free flight the complete collapsewill have occurred without the need of special provision. therefor.

Other objects and uses of the invention will appear from a detailed description of the same, which consists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a longitudinal section through the muzzle portion of a gun, and through a projectile exiting therefrom, said projectile being conveniently shown as of an armour piercing type, and provided with a base extension removably secured to the body of the shell, and said base extension being provided with gas passages incorporating the reaction principles which constitute a portion of the present invention; and this base extension is also provided with a telescoping sleeve which will shut ofi the orifices of these passages after the projectile has commenced its free flight, thereby preventing air flow through said passages at such time;

Figure 2 shows a section through the base portion of the projectile of Figure 1, free of the gun, and with the sleeve in its advanced position Where it shuts off the orifice of the passages;

Figure 3 shows' a. cross-section on the line 3-3 of Figure 2, looking in the direction of the arrows;

Figure 4 shows an outside or face view of the rear and cylindrical portion of the projectile of Figures 1, 2 and 3, with the sleeve in forward or orifice closing position;

Figure 5 shows a view similar to that of Figure 1, but it shows a modified arrangement in which the passage extension of the projectile is itself telescopingly carried by the body of the projectile, so that during the first portion of free flight said portion may slide forward over the body of the projectile, thereby reducing the overall length of the projectile to an amount not substantially larger than the length of the projectile without my improvements, andalso serving to close the orifices of the passages;

Figure 6 shows an outside or face View of the projectile of Figure 5, with the extension portion slid forwardly during free flight, a small portion of the sleeve portion and base of the projectile being shown insection;

Figure 7 shows a cross-section on the line 1-1- acestra irr'Figure 8, removed from the muzzleoizthegun; and'with the sleeve-portion slid forwardlypr 'collapsed into the condition which it assumes during:

Figure :10 showsa: cross-section on the line I 0-I 0 of FigurerB; looking inith'e direction of the arrows;

Figure 11lshowst alcrcss section on: the line I I-tI I of Figure 9, looking in'th'e direction of the arrows;

Figure -I2'showsxa series of characteristic curves of performance of 'a' typical three inch gun, to

show.thesgasapressures, velocities, temperatures,- energies, volumes; elapsed'times, and other factors, to illustrate the energies which are avail-- able; and .various factors of interest in an understandingsof the :fe'atures of the-present invention; and

Figure" 13 shows" a cross sectionthrough still another modified: form of base-portion of the projectile; and also shows by 'vector lines the directions and values .of 'components of gas velocity ofctheexiting gases under a typical instantaneous setfof conditions, and at'a-given instantin-the flight'of theprojectil'e.

Figure 14' shows a cross-section on theline Ii -Id ot Figure 5, lookingin the direction of the arrows; and

Figure 15"shows 'an end 'viewof the projectile ofFigures 5, Sand-7;

I willfirstreferto Figure 12 showingoertain" characteristics of performance-of a typical three inch .guntof well known type; The length of thegun is showrr as-ab'scis'sae along the -line Hit, and

various factors of performance-ere shown-'by'the ordinates along the'line I9 i5 Thebase-of the projectile initially "stands at the position I 92; so

that distances of travel are measured tothe-right" from'that position: For the gun'and conditions= assumed herein, the line 0fprojectile velocity is shown'at' I 03:'(ful1-*lih"e), and the line of gas pres sure is shown at 104:

the-gas pressure commences-to fall after the point Ifl5 has been reached, indicating that thereafter combustion is taking-"placeat a slower rate than the-'- increase of volume-- behind" the prcjectilefs" base. Still, combustion-is not complete; and com tinues-to substantially thepoint" shown bythe line H165 When the combustionis 'substantially complete (location of line Hi5) the adiabatic" expansion commences and -continues-to the time-'- of opening "of muzzlebyexit of the- 'projectile therefrom;

The total energy-(combustiontit-propellant) is shownby the line I91 Itris'es to th'e full combustion amount, and is then levelfromthe-point' forwardly to the muzzle, as shown by curve I912 The temperature of the gases within' the chamber and bore -is shown by the li'ne" I 885- lt' remains substantiallyconstant at the initial -'amount 'until combustionis -complete,- whereupon it fails I due The =maximum pressure pointattained'at I05 after-a travel of substan tial1y* 25inchesdown the bore: It is -notedthat' iii tOithGE'COIIVBI'SiOIL'Of energy of temperature and. pressure to otherzformsiof energy. The Volume of gasesunderipressuret'within the chamber and-1 bore behind the projectilebase'is shown by theline. I89; It rises regularly as :flight down the bore\ progresses. Inxthe. first analysisowe assume that full rifiing is provided in accordance with previouspractice;

The projectile energy (total) is shown'by the curve l ID. This curveisplotted on the: basis or assumption: of full .rifling, so that'the 'full amount of spinning-is due'to rifling. The friction .loss'of energy due to friction of the'projectil'e on the lands is computable, and is represented by the distance between the curve of projectile energy IIsand-"the next higher curveIII: The loss of energy byheating thebarrel, etc., is represented by the distance between thecurve III and the nexthigher'curve I I2; The loss oienergydue to recoil of the barrel'and parts is shown by'the II2' and the next distance between the curve higher curve I I3. The energy of velocityof: the

body of gases travelling along the barrel behind the projectile is shown by the distance between the curve II Band thenext higher curve H4;

Consequently, the elevation ofthe curve I I4 rep-' resents the combined energy of *the above: mentioned factors at any point-along the-barrel, and

likewise the elevations of the other curves repre sent the combinedamounts of-energie's of the several factors beneath them;

By deducting the-elevation of'th'e curve II from the elevation of 5 the curve- IilI we derive the curve I I5 whichrepresents' the'available energy of-the combusted-gasesat anypoint along the barrel, not including-the-gas velocity energy; and by adding to the 'curvel I5 the amount of gasvelocity energy'we 'get 'the curve I I Ii," representing the available energy at any-point alongthe barrel,- including the gas velocity energy.

Ihave also plotted the curve In representing the elapsed time at any point'along the *barrel needed for theproje'ctile to reach such point after commencement of flight, and the full line pertion of this curverepresents the condition forfull rifling.

I have also plotted the curve I I8 representing the factor B, for the formula PV RT; entering into certain of the computations herein made.-

Now it is noted thattherfricticn of the projectile bands on the lands of therifiing is very great, but heretoforenecessary in order to produce full spinning .of the projectile; soifwecan discontinue such rifiihg' at a point considerably short oi the muzzle of. the barrel we shall from that point ,forward correspondingly increase the acceleration of the projectile, since the gas pressure on the base of the projectile will be more fully applied to acceleration of the projectile. The soreduced spinning effectinust then be made up by some other power, and I propose to do this by the supplemental use of the expanding gases in manner to be hereinafter set forth. I have therefore assumed that rifling maybe discontinued at the location i it; and from that point forward to the muzzle I have plotted the supplemental or dctteds'line portions ofthe curves IIil, H'l-and Hi3, such dotted portions being indicated as i I0 I ii and it, respectively; It is noted that thereby the muzzle velocity has been raised from 266% ft/secs. to 2735 ft-./secs.*,1and that the muzzle energy has increased-from 703.'-l-"ft./tons to 77?.569 it./tons, and the elapsed time has been reducedfrom 0;6092931secs. 130030092539 secs;

being the elapsed: time from commencement of flight until exit from muzzle. These are possible benefits or improvements in performance existing at the instant of exit from the muzzle, and without taking into account the energy to be added by improvements of my invention, other than the ability to reduce or eliminate the rifling friction.

At this point it may be noted that due to the very high gas pressure existing within the barrel just prior to the instant of projectile emergence, said gases are very dense, and have a correspondingly high specific gravity; For example, in the assumed case the total mass of these products of combustion, amounting to 4.87M is contained within a volume of 0.780 cu. ft. at the instant of muzzle opening, so that at that instant their weight per cubic foot is 6.249 pounds, giving a specific gravity of approximately one-tenth that of water. This weight per cubic foot and specific gravity fall very rapidly upon opening of the barrel due to projectile emergence, but nevertheless for a short interval we have the condition of emergence of a mass of matter from the muzzle at very high velocity and under a condition of relatively high specific gravity. It is desired to extract useful work therefrom.

In connection with the curves of Figure 12, the following additional comments should be here made;

Knowing the curve of gas pressure, I 04, we are able to calculate from the area under this curve the total energy exerted on the base of the projectile during its flight down the barrel. This is found to be 920.65 ft./t. Deducting therefrom the totalmuzzle energy of the projectile (703.7 ft./t.) we get the difference of 216.95 ft./t. which is the loss due to friction during barrel flight. The form of the curve I I I may be similarly determined. Since the energy lost to the barrel by heat is assumed to be substantially equal to the friction loss to the barrel (see Ordnance and Gunnery, Tschappat, p. 145, ed. 1917) we may assume the heat loss to follow the line I I2 of Figure 12, being separated from the line III by the same amount as the line I I I is separated from the line IIU.

' At the instant of emergence of the projectile, the recoil energy can be computed as based on the formula (see Tschappat, above, p. 316), and the distance between the curves H2 and H3 is based on this formula.

The energy of translation of the unburned charge and gases may be computed according to the formula a (see 'I'schappat above, p. 138), and the distance between the curves H3 and H4 is calculated accordingly.

The time elapsed curve II1 was readily calculated from the form of the velocity curve IE3 of the projectile, knowing the distances along the barrel.

The temperature of combustion was estimated by the formula (see Tschappat above, p. '74). This was assumed to be the temperature up to the time of completion of combustion. Thereafter the expansion was assumed to be adiabatic, and the temperature and pressure curves were related as shown in Figure 12.

According to one important feature of my present invention I propose to so form the base portion of the projectile that as the release of gases commences and continues (after commencement of the opening operation), the gases are forced to react against the base of the projectile, or against other portions of the projectile, in such manner that the direction of said gases during release is violently changed or reversed, thereby effecting a great increase of dynamic reaction of said releasing gases against the projectile base, and ensuring delivery of a great additional amount of energy to the projectile before said projectile passes so far away from the muzzle as to make further benefit impossible.

Sometimes I so arrange the parts that the interval during which this reaction condition may con tinue is greatly increased; and sometimes I soarrange the parts that one or more reactions against the side portions of the projectile as well as its base may be secured; and sometimes I em-.

ploy various combinations of these several schemes.

In Figures 1 to 11, inclusive, I have shown several other arrangements embodying features of the present invention, and some of which are intended to make provision for still further increase of the time interval during which the expansion of the gases will take place under complete control. In the arrangement 'of Figures- 1, 2, 3 and l I have shown an arrangement in which the features of my present invention are applied to a typical form of large caliber armour piercing shell, and substantially without change of the form of the shell proper. In this case the shell 1% is provided with the nose portion I51 of well understood form, and with the high explosive charge I68, together with the fuse I69 set into the base block I'IEE. The usual sealing plate I1I is placed over the base block to prevent leakage of propellant gas into the interior of the shell.

In the present case I provide an extension on the base portion of the shell. Said extension includes the chambered member I12 which may be conveniently threaded to the base portion of the shell as shown at I13; and this chambered member is open at its rear end as shown at I 14, having the wall I15 which establishes the chamber I16. The front end of this chamber is suitably formed to provide the forwardly and outwardly and then rearwardly curved surface I11, and a plurality of gas discharge openings I13 are provided in the tions of the curved surfaces, so that forwardly flowing gases will be forced to flow over the backwardly curved portions of the surface I11 and can only reach the openings I18 after suffering a great'reversal of direction of flow as they,

leave the device. Preferably a follower band I19 is placed on the rear end of the extension wall.

I15; and if desired a leader band I may be provided on the rear portion of the shell proper,

and directly in advance of the threaded connec-- tion I13.

With the foregoing arrangement it will be seen that during normal flight down the barrel of the. gun both of the bands will seal with thelands of the rifiing. so that leakage is effectively pre-.

creepers vented. Assoc-n as therleaderibandzemergespfrom the muzzle the openings I18 become exposed and gas discharge from them :rcommences. The; follower band is still insea-ling engagement with the rifiing. The commencemcntofemergence of the openings I78 fromthem-uzzle isshowir in Figure 1. During flight from the instant ,ofemergence or exposure of the openings llfiluntil therear end of thexextension wall ;ll .emerg es fromthe muzzle, gas discharge through the openings 1 .78 will continue, with the discharging gases suffer.- ing violentreversal of direction and;generating a greatforward reaction-againstthe wall por tions Ill, in addition to the static 'pressureraof said, gases :against said wallportions; The-surfaces ll! (of Figures 1 and .2)1may-be soformed as-to produce a rotary-component of reactionvof the exiting gases on the base portion of the projectile so as r to .cause "the desired spinning: of the projectile without the need of 1 providing the usual rifling or .as a supplement to 'theieffect produced by such-riding; andlikewisethesurfaces of the .base of the projectile :shown -in:Figures i5, 6 and '7 may be-so formed as to produce such rotary component of reaction, and this is also true of the form of projectile shown in, Figures 8, :9, lO-a-nd ll. Thus-I :haveprovided for recuperation-of a lar e portion of "the energyof the expanding; gases and delivery of suchenergy intothe projectile as additional muzzle energy in addition togthat energy which would otherwise be delivered to .the projectile; Further.- m'ore il have provided means toexpa-nd the gases from their high pressure within the ,barrel just prior to opening of the muzzleofzthe. gumwith la relatively gradual expansion down-to a much lower pressure prior tocomplete-emergence-10f the projectile from-the. muzzle; and I have also provided arrangements. such that during such expansion of the gases at release a large portion of the so released energy :of :thegases 'will he recuperated in the formof muzzle energy of the projectile.

"The-time interval duringwhich such gas release and expansion-will take place-will depend on the distancebetween point'of commencement of opening of the openings H8 and emergence o'f the end portion of the =wall.,.l.1 5:-f rom the muzzle, and the velocity of travel of the projectile during that interval. Since thevelocity of-the projectile during that interval is still being increased, the integrated time interval for such travel will determine the problem. Furthermore, the rate of gas discharge will depend'pn the cross sectional area of the openings, the form of the passage, the gas pressure at'commencement of discharge, thenature of the gases themselves, and other .factors. The terminal or residual pressure existing Within the barrel when the wall I finallyemerges from the muzzle will also dependron the rate. at which .the gases have been escaping through the openings llii, theinitial pressure whensaid Qpeningsfirst-are exposed, the natureof the gases themselves-and various other factors. openings as respects size, contour, etc., the arrangement may be made -suchas .to .ensure...a great reduction of pressure during the fiexpansic-n interval, and-corresponding benefits ill-131 18 form of energy added to the projectile .rnay he 1 secured.

As an illustratiomin-the case of a sixteen-inch shell emerging with:a:velocity M2609 :ftr/seceat the instant of commencement ;o-f-exposure of the openings I18, and with the wall -,l:li i ofsuch By proper design .of the- 164 lengthaas to;requireza travel oi; three; feet during the interval of gas ''release. the time interval wouldwhe something iessthan .00115 see. This is a --very appreciable interval :of time in which to ficct s discharge under the conditions here existing, and a very-:-greatlowering of gas pressure may'rbe' attained during this interval and under the controlled conditions herein explained. A great addition of muzzle energy may 5 he. made to the projectile under these conditions and during such; time interval.

*Inorder toclose-the openings 478 aftergemergence:.ofthe wall -portion l 1-5 from the muzzle,;";[ have provided-thesleeve I 8 [surrounding the said wal-Lportionand:slidablethereon. This sleeve maybe-advanced far-.enough-zover the extension to coverttheaopfinings, as-yvill be apparent from F'ififllffi'i -W-herein that condition has been 'attained. It will be noted that during --accelera-. tion of the projectile during "its fiight down'the bore ithis sleevewwill remain in its rearmost position on therwall-rllfi (asshown in Figu-re 1') ,leaving-theopenings l 18-; open as shown in that figure; After emergence zof the: projectile complete- 1y fromthe muzzlethere will commence a-very rapid -deceleration of theprojectile due-to Wind resistance; so that -a 'forcewwill be thereby created tending to icause rsaid sleeve :to -move forwardly over the wall- H5 -torthe: closing .--position. Such deceleration may be as much as two or *three times "fG,- so --that --a -veryconsiderable "-foree --will be .:g enerated --ten1ingrtOqHlOVEgthG-TSIGGVE to the olosinggposition 'of Figure 4. Theclosing ofthe openings ill-8 vwillgprevent undesirable flow of air currents through theseopenings, and through the -passage orchamher I16 such: as would materially increase the resistance "of the projectile duringits free flight.

It. is notedthat-theiorM of-Figures .l, 2; 3 and 411550116 wherein the-projectile is provided with a -.permanent-;additicnto its length in aorder to secure the benefitszottheaddedtime interval during which the gases are beingrel-eased under completecontrol. .ln the arrangementof Figur es.5,.;6:-and 7 .-I.have shown arscheme in Whichsuchiextension portioni-islitseif =s1=idahly mounted on itheoutside otthe-shelLso that during free flight said-extension may advanceover. the shell and restore the overall dimensions of the projectile to substantially vthe size which they would have without such extension. In this case the sleeize-[32..cqnstituting thesextension proper is slid-ably :mounted on-theprojectile, being preferably. .splined .thereon as, shown especially in Figurejl. .The frontendof thissleeve is provided wit-ha .shouldered portion .I ,85 which will engage the properly shoulderedpor-tion .of the rear end of theprojectile when the extension is-in its rearmo th tiqn i a ia -fi ur 5) uringacceieration'inthebarrel. .On thecontrary, aitfir free flight cornmences the deceleration of the projectileinthe-air will causegsaid extension. sleeve portiorn'to move forwardly "over-the exterior of the-projectile into the position shown in Figure 6.

The base portion of the-projectile proper is formed as shown sothat-the desired curvature of surfaces is produced for recuperation of energy from-the exiting-gases either with or without :productionxof a rotary component of reaction on -:the :projectile; .The sleeve portion 1 82 isipcovideclavith thBLIJOI'tSJOIEODSIllllgS I84 which will:occupysthetproper positions with respect to the :said-;curved:suriace when. theiextension is in its rearmcstaposition. '{W'ith thisiarrangementzit is also desirable to provide the leader band I85 on the front end of the extension sleeve, and the follower band I86 on its rear end portion. Due to the splining of the sleeve on the body of the projectile the proper rotary driving connec tions will be established to the body of the projectile at all times, together with the proper gas sealing actions.

Examination of Figure 6 in particular will show that with this arrangement we are able to secure the greatly prolonged interval of time for gas discharge under complete control, and with the benefit of substantially no increase in the length of the projectile during the time of free flight. Furthermore, the central rearwardly extending portion of the base of the projectile, I81, serves to give to the projectile a boat-tailing form during free flight, with the attendant advantages.

In Figures 8, 9, and 11 I have shown a further embodiment of my invention wherein the features of the two forms just described are more or less combined into a hybrid form. Furthermore this arrangement of Figures 8 to 11 is one wherein a still greater time interval of controlled gas discharge is secured. In the present case I provide on the base portion of the projectile the permanent extension or wall I88, forming the chamber I89 of form similar to the chamber I16, and with the forward end of said chamber I89 having the curved surfaces I951 according to the previously explained arrangements. The openings I 9I are also provided for gas discharge. Then I provide the slidable sleeve I92 which may slide over both the extension wall I 88 and over the body of the projectile proper, the forward end of this sleeve being provided with the shouldered portion I93, and the rear end of the permanent extension wall I88 being provided with a corresponding shouldered portion I 94 to prevent complete backward freeing of the sleeve from the permanent extension. Both the sleeve portion I92 and the outside faces of the permanent extension I 88 and of the projectile proper are splined so that rotary driving connections are established between the sleeve I92 and said parts. Furthermore, the projectile proper may be provided with the leader band I95, and the rear end portion of the sleeve I92 may be provided with the follower band I96 as shown.

With this arrangement it will be seen that a very great increase of the time interval during which gas discharge under control will occur is secured, together with an increase of the permanent length of the projectile equal only to the length of the extension portion I88. The sleeve portion I92 will slide forwardly to its extreme forward postion after free flight begins, due to the aforementioned deceleration, and will thereby reduce the overall length of the projectile during free flight; and at the same time the forward movement of the sleeve I92 will result in closing of the openings I9I during free flight.

It is now apparent that I have herein illustrated and described embodiments of my invention wherein features thereof are usable in either light or heavy ordnance in which the gas pressures are very high, both during normal flight down the barrel as well as at the muzzle opening (the temperatures being correspondingly high); and they may be incorporated in other forms of ordnance in which relatively low pressures and projectile velocities are used, such as 16 mortars for throwing trench grenades and the like.

Now it is to be noted that the end products from the combustion of the propellant are complex, and include various gases, which have hereinbefore been referred to. These generally include 002, CO, H2O, H2, and N2. Of these the hydrogen and nitrogen are perfect or permanent or fixed gases, and they will follow the laws of such fixed gases closely during expansion of an adiabatic nature. Such expansion it is to be remembered takes place during the interval when the gas release openings are open, as well as during flight down the barrel after combustion is complete. Probably the CO2 will also follow these laws rather closely; but the H20 will probably be in a condition or partial dis-association due to the high temperatures existing within the barrel, and the condition of the CO in the presence of the CO2 and H20 within the barrel is uncertain. The H2 and 00 released by the reactions, will burn in the air after release from the muzzle, but this energy of combustion is not included in the estimate of available energy of combustion of the propellant.

If it be assumed that a greater recovery of energy by reaction according to the principles herein disclosed be possible in the case of release of permanent or fixed gases than in the case of such gases as CO2, CO, and H20, then it will be found possible to effect greater recoveries according to my invention when using propellants whose end products are higher in H2 and N2, and lower in CO2, CO, and H20, than vice versa. Accordingly, the following comments are in order;

Deca-nitrocellulose propellant contains substantially 12.75% N. This propellant (C24H30 (N02) 10020) gives end products as follows;

14CO2+ 10CO +2H2O 13Hz+ 5N2 with volumes of 14, 10, 2, 13 and 5, respectively;

total heat of 1,474,000 ft. lbs.

Ennea-nitrocellulose propellant contains sub stantially 11.966% N. This propellant (C24H31(NO2) 9020) gives end products as follows;

10CO2+14CO+4H2O+ll.5Hz+4.5Nz

with volumes of 10, 14, 4, 11.5, and. 4.5, respectively; total heat of 1,293,400 ft. lbs.

Octa-nitrocellulose propellant contains substantially 11.1l1% N. This propellant (Czdfiz (N02) 8020) gives end products as follows;

6COz+18CO+6H2O+10H2+4Nz with volumes of 6, 18, 6, 10 and 4, respectively} fixed or perfect gases in their end products. Still I do not intend to limit the use of the features of '5 (or iii-Figure 8, as the case rnay be). ti'ai'ling action will occuras I shall now explain:

end or -tlzu extension sleeve to exert back slii tl irebh, we ShaiLhaVe the: condition that I7 my present invention to the deca propellant, or any other specific propellant, except as I may do so in the claims to follow. The foregoing examples of certa'in propellants are given merely by way of illustration, and not by way of any limitation oi my invention or its features.

With respect to such embodiments of features army-invention as those shown in Figures to 7, inclusive, or 8 toll, inclusive, it is to benoted that in loading such projectiles as therein illustrated into the gun the slidable extensionrportions or sleeves (I82 or I92) should preferably stand in their forward or-telescoped positions when loaded, and prior to commencement of flight down the barrel,- as thereby the interference'with the charge in the chamber will be reduce'd tea minimum. For example, with the arrangement, shown in Figures 5, 6 and 7, the

length of the projectile when the extension I82 fs thus telescopedis substantially the same asvit would be without such extension member. Such at projectile may therefore be loaded into the gun in the's'ame manner as previously known tonneof projectiles not embodying the present hivhfion features.

such be'ingl the case itis evident that during flight down the barrel this extension member or a sleeve must a trail back of main-body of the projectile so that when the muzzle is reached theextension will be in its extended position. such as illustrated in Figure Such ons iderin'g the form of Figures 5, '6- and 7,

"when the extensionor s1eeve l-82 is set forwardly over the body of the projectile (into the position oi Figure-6), it it be assumed that there is no gas leakage between thesleeve and the body of the trout presprojectile, so that no gas can reach the acceleration force exerted entire sleeve-will L to the It is noted that the projectile proper, in the -case of a Ioa-deu: shell, is iiglitemfier cubic inch or cubic foot, than a solid body of stee or the like; so that the rate of --acceierauon of'tlie body portion of the projectile will be greater that we the telescoping sleeve element. Giins'ddehtly,

even under the ad-ve'rsecondition that no gas, pressure may reach the none-end or sleeve it is evident that the main body portion-of the projectile will accelerate faster the sleeve 'pbrliidn; SO' that by the tim'th projectile reaches.

the muzne the sleeve will have been setbackward its extreme distance into its working position. This fact further assured by reason of a the met that the friction or the fou ower band laser we on finer-ands is Iarge so that the major portion, 11 fiot an; the tric'tion; to be; overcome during acceleration is on the sleeve element,

- leaving? the main body portion of thenproj-ectile nee-w accelerate under the pressi'ire" being ex- 1:8 If there shouldbe leakageofi gas; pastthe sleeve so that pressure shouldbe exerted inadvance of it, we should have a still more favorable condition for ensuring the desired trailing action to which we have just referred. In somecases it may be desirable to ensure gas pressureagainstf the front-end of the sleeve so as to ensure t at said: sleeve will not be acceleratedas fast as the bodyof the; projectile, and to ensure that the sleeve will 'beextended back into its working position when the muzzle is reached. For this purpose passages such as 2380f Figure 6 maybe provided in the base portion of the projectile, same being'of: small size and merely for balance ofv gas pressureduring flight down the barrel'oi the gun.

Manifestly when a leader band is used invadvance of the gas openings, such band will seal against leakage of gas through the openings until the band leaves the muzzle, as which time gas discharge through the openings is intended to occur.

In the case of' armour, piercing shells and the like; .it may be notedthatwhen using a telescoping sleeve arrangement said sleeve is contained with the diameter of theshell as deter-m medby thebourr'elet. Consequentlythe action or the shell provided with features of my present vinvention is not materially changed. Furthermore it is to be noted that sucha telescoping sleeve is splined to the body of. the shell by spline connections at the front endoi the sleeve, so that when saidsleeve is advanced over the body of the shell such splined connection is close to the nose of the shell body. Now the radius of gyration of such a sleeve is large, since the entire mass of such sleeve is located at almost the full diameter of the shell. Consequently the rotary energyzof the sleeve constitutes a substantial proportionof the total rotary energy of the: projectile infree nigh-t. Due to the fact that the splined connection between the sleeve and thebody portion is close to the nose, such rotary energy of the sleeve is transmitted directly to the nose portion at the instant of'impac't;v and as a result the tendency of the projectile to twist off when the nose welds tothe armour plate or other obstruction is much-reduced.

Due to the' large radius of gyration of such an extension as the chambered. portion H5 or Figure 1, or lim -1920f Figure 9, it is evident that such extension in itself have a large amount of rotaryener'gyin addition to that 'of the'body portion of-the projectile. Due to this fact jis not necessary to provide for as high a rate oirotation with such forms of projectile asin theoase of projectiles not provided with such extension portiomand therefore the ridingwhen: used may be further reduced,- with consequent-reductions of cost of gun manufacture, and upkeep, as well-as reduction of friction loss on the lands.

It is noted that such permanent-extensions as shown in Figure la andelsewhere herein may: be readilyattached to-existing constructions of projectiles with relatively small cost, and with-the advantages "attendant-on the use thereof. It further noted that when loading a projectile hav ing-such a permar'ientextension,- a portion at least, of such extension may be allowed to reach back into the chamber; such case a portion,

at least; of the propellant charge may lee-loaded directly into the chamber of such permanent extension,- and thus without" interference with present designs org-nus and projectiles; Any change in the density ofloading entailed by such scheme "of loading may be readily compensated for in the loading calculations.

- It is noted that during the gas release interval,

the wall of the sleeve or of the extension is subjected to a bursting strain due to the gas pressure still existing within the barrel and such sleeve or extension. That pressure will commence at substantially the amount of the muzzle pressure which would exist at the instant of release had the features of my present invention not been =used (in the case shown by the curves hereof, amounting to 13,750 lbs/sq. in.). That pressure will then fall rapidly to its final value at the instant of complete emergence of the projectile. It is possible to worksuch sleeve or extension up close to the elastic limit of the metal thereof, so thewall thereof may be made relatively thin in comparison with gun designs themselves.

It is pointed out that the delivery of energy from the gas to the projectile in various forms herein shown is due to both the reaction of the gas against the base portion of the projectile, due

'- to its velocity and change-of direction, and also, in some embodiments herein illustrated, to the gas against the curved surface is much larger than such static pressure saving of energy during the interval of gas release through the discharge openings.

In an estimated case of a three inch gun incorporating features of my present invention the possible increase of projectile velocity is from 2600 ft./sec. to substantially 4000 ft./sec., with increase of muzzle energy from 703.7 ft. tons to substantially 1600 ft. tons; involving more than doubling the projectiles energy, and with corresponding increase of velocity at the instant of commencement of free flight. Such estimated increases are accomplished without reduction of rotary or spinning rate.

Of the foregoing estimated increase of projectile energy only a small portion is due to static pressure of the gases against the projectile base.

Now it is to be noted that increase of muzzle energy and efficiency by increase of gun length or number of calibers, so as to provide for increased expansion of the gases, is a totally different matter from the schemes herein disclosed,

since it does not make any provision for extraction of energy from the gases by means of the dynamic reaction principle. In any case, whatever may be the gun length, the further use of features of my present invention will afford further increase of projectile energy and gain of efficiency.

It is to be noted that, for any selected set of conditions the sizes of the gas delivery ports, and

the time interval during which controlled gas escape will occur, may be so determined that gas Y pressure reduction during this interval will be to some approximate final or terminal value, with corresponding improvements in performance. Manifestly, by increase of size of port openings the rate of gas discharge will be increased, with corresponding reduction of the time interval to secure a pre-selected drop of gas pressure prior to final complete emergence of the projectile from the muzzle, but too great size of these port openings is undesirable as it will result in partial loss of control of gas reaction during the gas discharge interval. On the contrary, too small ports will prevent sufficiently rapid drop of gas pressure to secure a desired small end pressure without too great length of the sleeves or extension on the rear end of the projectile, or corresponding scheme. It is therefore evident that in any case the various factors herein especially referred to should be properly related to ensure best or preselected results of operation. This can be done. I do not intend to limit myself to any specified proportions or sizes of these or other parts, except as I may do so in the claims to follow. I

In Figure 13 I have shown in fragmentary longitudinal section the base portion of still another detailed form of projectile embodying the features of my present invention. In this case the base portion 238 of the projectile has its rear face 239 so formed as to ensure gas discharge backwardly at an angle of substantially thirty degrees to the direction of flight which direction is indicated by the arrow. Furthermore, the base portion is so formed that definite rearwardly extending passages are provided through which the gases are discharged, said passages extending from the central or axial portion 240 to the discharge openings 2; and these passages are so formed that they include delivery portions prior to reaching the openings which delivery portions reach backwardly for an appreciable distance in such direction of substantially thirty degrees to the direction of flight, thereby ensuring a directed discharge in a definite direction with respect to the direction of flight. Consequently I am able to ensure controlled delivery of the gases prior to their expansion into the atmosphere, and with recovery of energy according to features of the present invention.

Now it is evident that the full recovery of energy which might be recovered (as hereinbefore analyzed) would be possible only in the assumed case that the gases were so delivered that they had no velocity after discharge. Such condition is not practically feasible, but may be approached. If the gases were to be delivered from the passages of the projectile with such projectile stationary said gases would have a backward velocity; but it is evident that they must also have a lateral or sidewise velocity so that they may clear the projectile and the gun itself. In other words, the passages should be so designed that they will deliver the gases outwardly as well as rearwardly. In the case shown in Figure 13 they are delivered through passages extending outwardly at an angle of thirty degrees with respect to the direction of flight, but any other suitable design might be substituted.

Now the forward velocity of the projectile at the instant of discharge of any small quantity of the gases being discharged must also be considered in determining the actual direction and velocity of gas delivery; and if the projectile velocity should be one half the gas delivery velocity (in the direction of flight) it would theoretically be possible to cause gas delivery without any velocity in the direction of flight, but nevertheless with some lateral velocity due to'the non-flight (or contranon-fiight) direction of gas delivery.

In Figure 13 I have shown by vector lines and more or less diagrammatically the relations between the several velocities just above referred to, and for three conditions of velocities. Thus, line 242 represents by its length and direction the velocity and direction of discharge of gases for the condition of stationary projectile, and under one 21 set of conditions; and the line 243 represents the corresponding velocity of projectile in its direction of flight. Then the line 244 represents the resultant of these two velocities, and therefore the actual velocity and direction of gas delivery under the assumed conditions of projectile velocity, gas delivery velocity, and direction of passages in the base portion of the projectile. Likewise, for a condition of greater projectile velocity and smaller gas discharge velocity the lines 245 and 250 represent the gas discharge velocity and the projectile velocity, and the line 241 represents the resulting actual velocity and direction of gas discharge; and for another condition of still greater projectile velocity and still smaller gas discharge velocity, the lines 246 and HI represent the gas discharge velocity and the projectile velocity, and the line 248 represents the resulting actual velocity and direction of gas discharge.

. It will be noted that if Vg represents the gas discharge velocity (with stationary projectile),

,and Vp represents the projectile velocity, and V1 represents the lateral component of gas velocity, then V1=V sin A; where A is the angle of gas discharge (stationary projectile) with respect to the direction of flight. Likewise, the component of gas velocity in the direction of flight (stationary projectile), which may be called Vf=Vg cos A. Again, taking into account the projectile velocity we find that the remaining velocity of the gases in the direction of flight, which may be called Vr=VfVp, or (substituting), VT=V cos AVp. This means, of course, that when the component of gas velocity backwardly equals the projectile velocity, the gases will be delivered directly outwardly, and with a velocity laterally dependent on the angle of the gas delivery portions of the passages in the base of the projectile. It is de-' sirable to keep that angle as small as possible in order that this lateral component may be as small as possible, and with consequent reduction of final wastage of energy in the gases due to velocity, since that energy depends on the square of said velocity.

It is also evident from the above analysis that in case of a projectile velocity greater than the backward component of gas delivery velocity the gases will have a forward component of velocity at delivery.

Now the determination of the actual possible recovery of energy from the discharging or exiting gases is a complex determination, and it involves consideration of many factors, some of which include constants of uncertain value and kind. Still it is possible to make an approximation of the amount of such recovery; and for this purpose I have made use of what I may call the Quantum method. By this method the total distance of travel of the projectile from the instant of commencement of opening of the discharge openings to the instant of complete exit of the tail end of the projectile from contact with the muzzle (in other words, the total travel of the projectile while gases are being delivered under control), is subdivided into numerous small distances or differentials of travel, and the conditions of gas pressure, temperature, velocity of discharge, etc., are analyzed and determined for each of these zones or positions, or stages. The procedure is then as follows:

1. Projectile velocity and gas velocity at commencement of stage are assumed to be equal.

2. Estimated velocity of emergence of gas from orifices during travel through stage was based on estimated total energy remaining in gas (ignoring gas velocity energy, see curves), and on total mass of gas remaining in barrel, and this estimated velocity was taken as the velocity of emergence of the small quantum of gas which would emerge during the travel through the stage in question. The energy necessary to press back the atmosphere was also deducted in estimating the available energy to create gas velocity, as well as the energy remaining in the expanded gases in the form of heat, above zero Cent.

3. The time consumed in travelling through the stage was estimated on the basis of projectile velocity at the beginning of the stage.

4. The length of travel of the emerging gases during this interval of time was found.

5. The volume of gas discharged during this interval of time was estimated on the basis of the length of the stream of gas discharged as above calculated.

6. The original volume of gas was taken as the volume at the beginning of the stage.

7. The equivalent volume of gas in its expanded condition at the end of the Stage was calculated as the original volume at the beginning of the stage plus the volume discharged.

8. The pressure of thegas remaining in the barrel at the end of the stage was calculated from the equivalent volume at the end of the stage by the formula PV=P'V.

9. The average pressure existing in the barrel during the stage travel was calculated as the mean between the pressures at the beginning and ending of the stage travel.

10. The work performed on the base of the projectile during travel through the stage was estimated from this average pressure (being work due to actual pressure on the base of the projectile) 11. The friction loss during travel through the stage was estimated from the length of travel and assuming a total friction of 2500# (for three inch projectile), there being no rifling.

12. Work performed on the base of projectile (10) minus friction loss (11) equals pressure energy available to increase total energy of projectile.

13. The temperature of the gas at the end of the stage was found from the formula PV=RT, and on the assumption that R. varies regularly from the value of 3.792 at the muzzle to the value of 3.74.06 for full expansion.

14. The heat loss to the barrel and parts during the travel along the stage in question was estimated as follows: It was assumed that the curves) Then energy 1055 per sec. per degree Cent. equal .fl .0039231 2860 7 T.

Having the foregoing constant, it is possible to estimate the heat loss to the barrel during each stage examined, assuming the velocity equals that at the beginning of the stage, the temperature having been found from 13.

15. Deducting energy performed on base of projectile (10) and heat loss to the barrel (14) from apply theratio .of- (1.6)

energy atxbeginning of stage we getenergy available-to give .velocity .to the expanding gase -or energyremaining in the gasatend of. stage.

.This'will be total energy in the; body-of. gas .re-

' equivalent .volume. isthen applied to the mass of gas in thebarrel (and stages); .at the beginning of .the stagev being examined, thereby ascertaining actual amountof gas dischargedduring the. stage.

17....10 ascertain the: energy. carried. out of the barrel (and stages) by the discharged gas. we This ratio applied to the, energy remaining in the gas at end. of stage (15) gives energy remaining in gas still enclosed; and energy. remaining in gas. still enclosed deiductedhfrom total remaining energy at end of stage (15) gives energy to create velocity in discharged gas (found in 16.). -Thereby we are able to compute velocity-of discharge of gas during the stage in question. 1

18. Gas discharged flows insome direction determined by velocity of discharging gas (absolute) compared .to velocity of' projectile. during the stage in questiomand taking account of angle of discharge (assumed asthirty degrees). For

this. purposeuse .was made of a vector diagram for each stage. Onthis diagram the velocity of gas discharge was plotted: backwardly and outwardly. at thirtydegrees from the. direction of flight; then directly forward (at velocity equal to projectile velocity); and the resultant. gave the actual velocityand. direction ofgas delivery.

By the use of such. an analysis, applied to each of numerous; stages it was possible to estimate the probable recovery of energy in the. given case of a; three inch gun; and .it wasv found that it should be. possible thereby to recover energy suincient to double or more the projectile. energy at the muzzle of the gun, compared to previous practice, not making. use of features of my present invention.

Where in the claims to follow I speak of a shot section of the projectile I contemplate not only projectiles having solid shot bodies but also; projectiles having loaded. or explosive or shell sections.

1 claim:

surface facing towards the gases released from the gun with which said projectile is intended arc ers t be .used, whereby he gases. as released from the muzzle of the gun duringfli ht of the prowiectile from said muzzle-impuls a ai st such surfaces of. the projec il -base and are deflected reerwardly with: consequent increaseef muzzl ener y of the projec ile. t gether with a rearwardly extending skirt telescopingly mounted on. the projectile ofsize to cooperatewith thebore not the gun and maintain substantially as tight engagement with the gun bore after passa e of the aforesaidcurvedsurface past the. muzzle of the; gun and. untilideparture of saidski-rt from the muzzle :of the gun, said skirt having. a. series ofi-gas discharge orifices therethroughsubstamxtiallyin. the :zone of the peripheryof said rearwardly curved surface aforesaid, for discharge of gases during the intervalbetween. passage of gtheperipheral portion of said. curved surface 118- yond. the muzzlezef the. gun and the time of. flight of said skirt portion from the gun muzzle, substantially as. described.

2,. In apriojectile as defined in claim .ljth at improvementzcomprising the telescoping of said skirt externally of the shot section, for telescoping movement forwardly over the shot section.

during. deceleration. otlthe projectilerafter. com- -.mencement of. free. flight, to thereby reducethe 1 men-t with the bore of thegun: after passage of said gas discharge: openings beyond the muzzle of the gun, substantially as described. r 4 In a projectile asdefined claiml, Where in said forwardly and; outwardly; and, rearwardly curvedsurface is also curved: angularly with re- 'spect :to the axis of the projectile, whereby the. gases are discharged through said" openings with a componentof movement in a: rotary direction about the axis. of the. projectile. to thereby create a rotativev force on the projectile. to spin said projectile, substantially as described.

JTHOS. Ar BANNING; JR.

n res-traces ones The following references are of record in the file of this patent: r

I UNITED STATES PATENTS Number Name Date,

1349444 Quisling. -s. ;..DBc. 3 .1, .1912

1 4503558 .Maze Apr. 3, 1923 1,628,527 .Brandt May 10, 1927 a r 1,879,579 Stolfa etal. Sept. 27,1932

FOREIGN PATENTS Number Country Date 269,412 Great Britain A1912. .21, 192.7

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