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Патент USA US3050034

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Aug. 21, 1962
B. w. MCCORMICK ET AL
3,050,024
TORPEDO PROPULSION AND CONTROL
Filed June 26, 1957
3 Sheets-Sheet 1
1FIG.
BARNES W. M‘CORMICK
JOSEPH J. EISENHUTH
GEORGE F. WISL/CENUS
IN VEN TOR.5
Aug. 21, 1962
B. w. MCCORMICK ET AL
3,050,024
TORPEDO PROPULSION AND CONTROL
Filed June 26, 1957
3 Sheets-Sheet 2
BARNES W. M‘CORM/CK
JOSEPH J. E/SENHUTH
GEORGE F. W/SL/CENUS‘
IN VEN TORS
FIG. 3
BY
I
Z6”
7/4
_' AT ORNEYS
Aug. 21, 1962
B. w. MCCORMICK ET AL
3,050,024
TORPEDO PROPULSION AND CONTROL
Filed June 26, 1957
3 Sheets-Sheet 3
O
Propeller .::.§
‘"25
FIG. 8
BARNES W. M‘CORM/CK
JOSEPH J. E/SENHUTH
GEORGE F. WISLICENUS
IN VEN TORS
BY
|
' 'ArroR/vEys
United States Patent @?fice
3,050,024
Patented Aug. 21, 1962
2
1
in cross-section each station indicated in FIGURE 2 and
showing the disposition and con?guration of the cross
3,050,024
TORPEDO PROPULSION AND CONTROL
Barnes W. McCormick, Spring?eld, and Joseph J. Eisen
huth and George F. Wislicenus, State College, Pa., as
signors, by mesne assignments, to the United States of
America as represented by the Secretary of the Navy
Filed June 26, 1957, Ser. No. 668,267
6 Claims. (Cl. 114-20)
section of each station with relation to the cross section
of each other station, a hypothetical stack-up line which
passes through each cross-section, the angle at which each
cross-section is disposed with reference to the longitu
dinal axis of the torpedo and the camber of each cross sec
tion.
FIGURE 4 is a front elevation of one ?n showing in
This invention relates generally to torpedoes and more 10 particular the twist or skew in the leading edge of the
?n.
particularly to propellers and stabilizer surfaces for a
FIGURE 5 is a rear elevation of the ?n shown in FIG
torpedo. As used herein, “stabilizer surfaces” have ref
URE 4 and shows in particular the twist or skew in the
erence to the ?xed means utilized to render a torpedo
trailing edge of the ?n.
stable during travel which generally also contains mova
FIGURE 6 is a fragmentary side elevation partially in
ble “control surfaces” for controlling or changing the di 15
section of a propeller and ?n combination in accordance
rection of travel of the torpedo,
with the invention and showing the intersection of the
The concept of propelling torpedoes and maintaining
streamline with the propeller and ?n at mid-chord radii
them stable in travel has remained unchanged almost
of respectively rp and rf.
from the date of the ?rst practical torpedo. This con
FIGURE 7 shows the relation of the cross section of
cept generally includes a long cylindrical body having a
the propeller at the radius rp to the cross section of the
tapered rearward portion provided with a propeller at the
?n at the radius r, shown in FIGURE 6 and also shows
most rearward point and usually four ?xed stabilizer sur
velocity diagrams for the streamline of FIGURE 6 at
faces extending outwardly at right angles just forward of
these respective radii, the velocity diagram at the radius
the propeller. The prior art is replete with innovations
of the basic concept, but for both practical and technical 25 rp being shown adjacent the propeller cross section and
the velocity diagram at the radius rf being shown adja
reasons few, if any, have as yet ever met with substantial
success or come into Widespread use.
Further, the above
mentioned innovations have almost without exception
been concerned with providing increased power, increased
efficiency, increased stabilization, increased maneuver
ability and the like.
It was not until recently that designers of torpedoes be
came interested in the noise generated by the torpedo dur
cent the ?n cross section.
FIGURE 8 is a velocity diagram at the quarter chord
line of a ?n constructed and formed in accordance with
the invention.
FIGURE 1 shows the rear portion 15 of a torpedo of
conventional design having a substantially smooth outer
surface 16 over its entire length and provided with a
propeller 17 attached to its rearmost portion and adapted
ing travel and this has led to a considerable interest in the
phenomenon of cavitation. However, so far as is known, 35 to propel the torpedo in a forwardly direction by con—
ventional means such as for example, an electric propul
heretofore all such efforts to reduce noise with regard to
sion motor, propeller shaft and associated components
(not shown.) Disposed rearwardly of the propeller 17
into practical use, especially with regard to the develop
ment of a hydrodynamically stable torpedo that is fast, 4.0 and af?xed to the rear portion 15 of the torpedo in non
rotatable relationship therewith are a plurality of sta
that produces a minimum of noise and that can be
bilizers or ?ns 18 (in this case, eight) integrally mounted
launched in accordance with conventional methods.
on a hub 19 the exposed outer surface of which forms
It is, therefore, a principal object of this invention to
a continuation of the rear portion 15 of the torpedo and
provide a propeller and stabilizer surfaces for a torpedo
cavitation have not met with substantial success or come
the propeller hub 21. As best shown in FIGURE 2'
45
and by way of example, the hub for the stabilizers may
Another object of this invention is to provide a propel
be removably attached to the torpedo by means of a rigid
ler and stabilizer surfaces for a torpedo having improved
shaft 22 non-rotatably disposed within a hollow propeller
cavitational characteristics.
shaft 23 and a bolt 24 adapted for threaded engagement
A further object of this invention is to provide new and
novel stabilizer surfaces for a torpedo that cooperates 50 with the rigid shaft 22 or the like and provided with a‘
conical rear portion 25.
with the propeller in a new and novel fashion.
For the number of fins shown in FIGURE 1 the hub 19
A still further object of this invention is the provision
for the stabilizers is preferably formed separately and the
of a propeller and stabilizer surface arrangement that will
root section 26 of each completed ?n 18 permanently at
et?ciently propel a torpedo by means of a single propel
ler while maintaining a zero net torque and that will be 55 tached thereto as \by welding or the like. In the preferred
that result in improved torpedo performance.
less susceptible to cavitation and will be more effective in
embodiment as shown in FIGURE 1 each ?n 18 extends
controlling the torpedo.
radially to about the diameter of the torpedo and the
leading edges 27 of each stabilizer surface or ?n 18 is
disposed about within one ?n chord length of the rearmost
Another object of the invention is the provision and
location of new and novel stabilizer surfaces for a torpedo
that are less susceptible to cavitation and that allow the
use of propellers having improved cavitation character
istics.
These and other objects and features of the invention,
together with their incident advantages, will be more
readily understood and appreciated from the following
detailed description and the drawings which illustrate an
embodiment of the invention in which:
trailing edge 28 of the propeller 17.
As shown in FIGURE 2 and FIGURE 3 each ?n 18 has
a plurality of stations designated respectively A, B, C, D,
E, F and G wherein the radial cross section of each
stabilizer surface or ?n 18 at each different station is
disposed at a speci?c and individual angle to the longi
tudinal axis of the torpedo (represented by lines 33 in
FIGURE 3) and has a speci?c camber the determination
of which is described hereinafter. By reference to and
FIGURE 1 is a perspective view of the rear portion
inspection of FIGURE 2 and FIGURE 3 it can readily
of a torpedo incorporating the present invention.
FIGURE 2 is a fragmentary side elevation partially 70 be seen that each stabilizer surface or ?n 18 has an indi
vidual stack-up line 31 passing through different points
in section of one ?n mounted on a hub and showing the
in the cross sections of each different ?n at each station
location of various stations on the ?n.
and that each l?n is respectively twisted or skewed the
FIGURE 3 is a diagrammatic representation showing
‘3,050,024
3
4
same amount and in the same manner about its stack-up
being designed to replace conventional stabilizer surfaces
disposed and mounted forwardly of the propeller substan
line 31 such that the leading edge 27 of each ?n forms
tially the same degree of stability will be maintained if
the following is held true:
an arcuate surface both in a longitudinal and radial direc
tion as shown in FIGURE 4 and such that the trailing
edge 32 of each ?n forms an entirely different arcuate edge
as shown in FIGURE 5 as and for the purposes described
(1)
hereinbelow.
The remaining restrictions on the chord distribution are
In order to fully describe the construction and opera
those imposed by ?n cavitation performance as will be
tion of the ?ns 18 reference is now made to FIGURES 6
through 8 of the drawings as an aid in the description of 10 more thoroughly discussed hereinbelow.
The design of the ?n for torque cancellation requires
the manner employed in formulating the ?ns and to fully
the determination of the radial distribution of bound cir
describe their vunique con?guration.
culation I‘f that will be needed for torque cancellation.
The preferred ermbodiment of the present invention con
With reference now to the propeller-?n combination
templates the operation of a normally ?xed set of stabilizer
34-35 as shown in FIGURE 6 and which is merely rep
surfaces or ?ns immediately behind a given single pro
resentative, it will be noted that the streamline 36 which
peller, that the stabilizer surfaces or ?ns satisfy the sta
passes through the propeller 34 at midchord at a radius of
bility requirements of the torpedo, that they produce a
net torque equal and opposite to that produced by the
rp, intersects the ?n 35 at midchord at a radius of rf. A
propeller and that they have a cavitation performance at
representative velocity diagram for the streamline 36 rela
least as good as that of the propeller.
tive to the propeller section at radius rD and the ?n section
at radius rf is shown in FIGURE 7. Because of the mag
nitude of the angles involved the assumption may be made
that the induced velocity wt of the ?n section lies in a
transverse plane as shown in FIGURE 7 and therefore
has no axial component. The rf having the same inflow
as that at rp may be calculated from continuity considera
Since the con
?guration of each '?n is substantially identical with every
other ?n, reference is made hereinbelow in substance
to the design of a single ?n.
In the following discussion let:
ri=radius at which streamline passes through the ?ns at
midchord
rpzradius at which streamline passes through the pro
peller at midchord
rph=hub radius of propeller
tions as
rr=\/rp2—rph2+r??
3O
rm=hub radius of ?n
Rp=propeller radius
w=rotational speed in radians per second
wt=tangen=tial velocity induced by propeller
wa=axial velocity induced by propeller
k=spacing factor giving change of wa with axial distance
For best operation and especially for good cavitation
performance the stabilizer surface or ?ns must be designed
to operate with a speci?c propeller or type of propeller,
hence from the design of such a propeller induced veloc
ities of the propeller will be known and the following ex
pression, for torque of the propeller not including pro?le
losses, can be written:
wf=induced velocity of the ?n section
wf,25=velocity induced by the ?ns at the quarter chord-line
F :Prandtl’s tip loss factor
Bpznumber of propeller blades
(2)
R
QD=BDP T Jami/wear.
D
40
(3)
‘The torque of the ?ns corresponding to the velocity
diagram shown in FIGURE 7 can also be written, again
neglecting pro?le losses, as:
Bfznumber of ?ns
Fir-abound circulation of ?ns
I‘p=bound circulation of propeller blade
p=?uid mass density
Initially, it may be convenient to cancel torques locally.
Qp=torque produced by the propeller
Therefore, again from continuity considerations, where
Qf=torque produced by the stabilizer surfaces
l3=propeller blade section angle
rfdrf=rpdrm Equations 3 and 4 lead to the expression:
?1=angle from transverse plane to zero lift line of a ?n
section
?m5=angle from transverse plane to a tangent of the mean
camber line at the quarter chord point
lf=distance of ?n from the torpedo center of gravity for
new design
l'r=distance of ?n from the torpedo center of gravity for
existing torpedo
V'=in?ow velocity at stabilizer surface of existing
Since as already mentioned, ‘the ?ns are preferably de
signed to extend to substantially the maximum radius of
the torpedo, it is important from the point of view of
cavitation to extend loading of the ?ns over the ‘full radius
of each ?n. For this reason it is preferable to ?rst calcu
late I‘f from Equation 6 and then to modify this I} to
extend out to the full radius of the ?ns, maintaining the
Cf=?n section chord of new design
60 same total torque but leaving unchanged the 1‘; near the
C',=?n section chord of existing design
hub for the purpose of minimizing the possibility of a
R’f=?n radius of existing design
cavitating hub vortex.
r’fh=hub radius of ?n for existing design
Once the radial distribution of I} for torque cancella
tion has been established the physical con?guration of the
In the design of ?ns as contemplated by the present
invention stability requirements involve the choice of a ?n 65 sections, i.e., the ?n section angles, the ?n section cambers,
and the like may be determined in the following manner.
planform with suf?cient area to stabilize the torpedo. In
The ideal approach for the design of each ?n would be to
the preferred embodiment the total ?n height is restricted
use an exact lifting surface theory for a ?n in a rotational
to the diameter of the torpedo, hence the area is therefore
in?ow. Such a formulation is, however, an imposing one.
dependent on the choice of the radial chord distribution
torpedo
and should be such as will meet the stability needs of the 70 Also, no readily usable factors are available such as
Prandtl’s “tip loss factor” or Goldstein’s “K” factor used
torpedo. It has been found through experience that
Equation 1 as given hereinbelow may be used for ?nding
the necessary chord distribution for replacing conventional
stabilizer surfaces and consequently allowing a determi
nation of chord distribution.
in propeller design whereby the circulation may be related
to the induced velocity at each section as a function of the
relative radius, angle of in?ow and the number of ?ns
If the new ?n or ?ns are 75 involved. An acceptable approach, the validity of which
—
3,050,024
5
has been proven by experience, is to use Weissinger’s lift
camber, the geometry and orientation of each section is
ing surface approximation ‘for wings described in “The
Lift Distribution of Swept-Back Wings,” 1'. Weissinger,
satis?ed by ?nding the camber which will satisfy Equations
N-ACA TM. No. 1120, March 1947, which accounts for
tion if desired may be based on mechanical considerations
rather than on hydrodynamic considerations.
the rotational in?ow only as a non-uniformity in the in?ow
7 and 8, simultaneously. The choice of thickness distribu
Certain aspects of improving the cavitation performance
velocity. Weissinger’s so-called L-rnethod states in sub
of the ?ns have already been mentioned hereinabove. For
stance that for a given lifting surface, if the bound cir
instance, it was noted that the chord distribution must
culation is assumed to be located at the quarter-chord line,
meet the requirements necessary for good cavitation per
then the distribution of the bound circulation must be
such that the resulting ?ow is tangent to the surface at 10 formance. One of the ways in which cavitation perform
ance may be improved is to increase the ?n or force
the three-quarter chord line. This is equivalent to the
producing area so that the cambers required and con
statement that the angle of the resultant velocity at the
sequently the magnitude of the minimum pressures are
three-quarter chord point must be the same as the angle
reduced for the individual hydrofoil sections. One of the
of the zero lift line. This angle, and hence the angle for
each section, may be established by determining wf at each 15 controls available for ?n area is the distribution of chord
along each ?n, hence increasing the chord lengths will
station or alternately, from the geometry of FIGURE 7
improve the cavitation performance. Further, the total
and by use of the formula:
?n area may also be increased by increasing the number
of ?ns to allow a reduction of the loading on each ?n
and thereby improve cavitation performance.
The determination of the values of W: is most conven
iently accomplished by the use of an electromagnetic
analogy. The analogy that may be utilized is that of
substituting the magnetic ?eld about a conducting wire
Still further, as mentioned hereinbefore, the choice for
the 1} distribution is another control that may be used to
improve cavitation performance. By redistributing I} to
be substantially constant over the majority of the length
for the induced velocity ?eld about a vortex. In the 25 of the ?n no particular section will be overloaded and
con-sequently will have no accompanying poor cavitation
analogy referred ‘to hereinabove a common wire repre
senting the bound vortex is located at the quarter-chord
performance. Further, the maintaining of 1} equal to the
propeller I‘ near the hub reduces the possibility of hub
line and to it are attached other closely spaced wires rep
resenting the trailing vortex system. A source of alter
vortex cavitation. Still further, the gradual decreasing of
If near the tips of the ?ns reduces the possibility of tip
nating potential is connected to these wires and is dis
tributed in such a manner that the span-wise distribution
of current in the bound vortex wire is proportional to the
vortex cavitation.
span-wise distribution of P1. By measuring the induced
voltages at the three-quarter chord point these voltages
tained by camber alone thereby allowing a substantially
As noted hereinabove all the lift of the sections is ob
constant chord-wise distribution of pressure to be main
may be translated into induced velocities. The effect of 35 tained at the sections and it is the presence of such a dis
tribution that prevents the existence of low pressure cavita
numbers of blades may be obtained by again taking meas
tion producing regions. NACA Series 16 sections which
urements at the relative positions of other ?ns at the
have the ?at pressure distribution just mentioned for zero
three-quarter chord points. By adding the results the
or very low angles of attack have been used in practice
effect of the entire system of ?ns may be obtained.
The analogy and use thereof referred to hereinabove 40 with satisfactory results and may be used if desired.
The provision of stabilizer surfaces designed to operate
is thoroughly discussed and described in “Development of
in combination with a propeller (as shown and described
Electromagnetic Analogy for Computation of Induced
herein), thereby allowing the propeller ‘to be designed
Propeller Velocities,” a thesis by Barnes W. McCormick,
for operation on a clean torpedo body of speci?c design,
Jr., published 1949, the Pennsylvania State University, to
which reference is made. The determination of wt, such 45 has shown that the index of cavitation for both the
propeller and stabilizer surfaces on such a torpedo may be
as for example in the manner described immediately here
reduced over that presently existing with regard to prior
inabove allows the determination of the direction of the
practices by as much as a factor of four or ?ve and at the
zero lift line of each station along the ?n. The determina~
very least a cavitation index may be secured that is gener
tion of the angle of zero lift for each station allows the
determination of the proper cambers and section angles 50 ally not obtainable with prior art practices under even the
most ideal conditions.
on the basis that, for good cavitation performance all of
It will be readily appreciated that in the arrangement
the lift of the sections must be obtained from camber
and development illustrated in the drawings and described
rather than by any angle of attack. The proper determina
by way of example hereinabove may be varied and modi
tion of camber requires that the camber of the sections
be determined on the basis of the stipulation that the 55 ?ed according to requirements. As may be apparent
latitude is available in the design of the ?ns with regard
resultant velocity at the quarter-chord line be tangent to
to ?n area, ?n length, number of ?ns and section camber
the mean camber line at that point ‘for the reason that
and section angles and the like since they are generally
determination of the zero lift line and the slope of the lift
interdependent, the modi?cation of one being compensated
curve of a section is not su?‘icient for the calculation of
a lift coef?cient, ‘and hence, the camber of the section since 60 by or allowing modi?cation of another to a greater or
lesser extent. Moreover, the present invention is not
the velocity that must be used as a reference for the angle
necessarily limited to a single propeller application, al
of attack is not clearly de?ned. As noted immediately
though such is believed preferable, and may be adapted
hereinabove the determination of the resultant velocity is
for steering a torpedo.
dependent on ?nding the induced velocity Wf_25 at the
quarter-chord point as shown in FIGURE 8 which induced 65 It is, therefore, to be understood that while the present
invention has been described in its preferred embodiment,
velocity may be found by integrating Biot-Savart equations
it is realized that modi?cations may be made, and it is
or by use of the electromagnetic analogy, reference to
desired that it be understood that no limitations upon the
which has been made hereinabove. The angle of the
invention are intended other than what may be imposed
resultant velocity may be determined from the formula:
70 by the scope of the appended claims.
let-25 =taIF1
V-l-kFun )
(8)
2Fw¢ — wf.25
Since vfor a given family of airfoils, the angle of zero lift
What is claimed as new and desired to secure by
Letters Patent of the United States is:
1. Stabilizing means for a torpedo having propulsion
means including a propeller at its rearward end com
and the slope of the mean camber line at the quarter-chord
point may both be known as a function of the maximum 75 prising: a non-rotatable hub element disposed rearwardly
3,050,024
g)
7
0
of the propeller and on the longitudinal axis of the tor
pedo; means connecting said hub element to the torpedo;
and a plurality of ?ns radially carried by said hub and
having a plurality of diiferent stations, said ?ns having a
predetermined angle and camber for each said diiferent
station determined by the propeller water exit conditions
at each said different station, said angles and said camber
creating a net torque equal and opposite to that created
?n middle portion having ‘a substantially ?at load char
acteristic less than the maximum load characteristic of
the propeller, said ?n outer portion having a load charac
teristic that decreases in an outwardly radial direction,
each of said ?ns having a plurality of radially disposed
di?erent stations, said ?ns having a predetermined angle
by the propeller in operation and reducing the magnitude
and camber for each said di?erent station determined by
the propeller water exit conditions at each said different
station cooperating to produce a net torque equal and
of low pressure areas on the ?ns.
opposite to that created by the propeller in operation and
reduce the magnitude of low pressure areas on the ?ns.
2. Stabilizing means for a torpedo having propulsion
5. The combination as described in claim 4 wherein
means including a propeller at its rearward end compris
there is provided a minimum number of said ?ns such
ing: a non-rotatable hub element disposed rearwardly of
that the projected area of said ?ns in ‘any one plane is
the propeller in close proximity thereto and on the longi
tudinal axis of the torpedo; means connecting said hub 15 sut?cient to maintain stability.
6. In a torpedo having ‘a substantially smooth outer
element to the torpedo; and a plurality of ?ns radially
surface and propulsion means including a propeller at its
carried by said hub and having a plurality of different
rearward end the combination comprising: a propeller,
stations, each said station having an airfoil cross section
said propeller being designed for operation with said
disposed at a predetermined angle to the flow of water
smooth torpedo body; a non-rotatable hub element dis
from the propeller at each said station, each said di?er
posed rearwardly of the propeller in close proximity
ent station additionally having a predetermined camber
thereto and on the longitudinal axis of the torpedo;
for producing a torque opposite to that created by the
means connecting said hub element to the torpedo; and
propeller in operation, the net torque produced by the
a plurality of ?ns radially carried by said hub and hav
?ns being substantially equal and opposite to that cre
ing a plurality of different stations, each said station hav
ated by the propeller, the said angle of each said station
ing an airfoil cross section disposed at a predetermined
substantially reducing the formation of low pressure
angle to the flow of water from the propeller at each said
areas over substantially the entire surface of each said
station, each said different station additionally having a
?n.
predetermined camber for producing a torque opposite
3. The combination as described in claim 2 wherein
the camber of each diiferent station is selected such that 30 to that created by the propeller in operation, the net
torque produced by the ?ns being substantially equal and
the resultant water velocity at the one-quarter chord line
opposite to that created by the propeller, the said angle
is tangent to the mean camber line at that point.
of each said station substantially reducing the formation
4. Stabilizing means for a torpedo‘ having propulsion
means including a propeller at its rearward end having
an inner portion and a predetermined load characteristic
comprising: a non-rotatable hub element disposed rear
wardly of the propeller and on the longitudinal axis of
the torpedo; means connecting said hub element to the
torpedo; and a plurality of ?ns radially carried by said
hub, each said ?n having an inner portion, a middle por 40
tion and an outer portion, said ?n inner portion having
a load characteristic substantially the same as the load
characteristic of the inner portion of the propeller, said
of low pressure areas over the entire surface of each said
?n.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,355,413
2,746,672
2,795,394
2,798,661
Bloomberg ___________ __ Aug. 8,
Doll et a1. ___________ __ May 22,
Slivka et al ___________ __ June 11,
Willenbrock et \al. ______ __ July 9,
1944
1956
1957
1957
at’a.wA"3.
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