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Патент USA US2121536

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June 21, 1938.
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‘
J. A. J. 'BENNETT
2,121,536
AIRCRAFT SUSTAINING ROTOR
Original Filed‘Sept. 14, 1935
4 Sheets-Sheet 1
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ATTORNEYS
I June 21, 1938.
I
J. A. J._ BENNETT
2,121,536
‘AIRCRAFT SUSTAINING ROTOR
Original Filed ‘Sept. 14, 1935
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4 Sheets-Sheet 2
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JINVENTOR
-
BY
June 21, 1938.
J. A. J. BENNETT
2,121,536
AIRCRAFT SUSTAINING ROTQR
Original Filed“ Sept. 14, 1935
4 Sheets-Sheet 3
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1
INVENTOR
.
ATTORNEY¢$
.
June 21, 1938.
J, A, J_ BENNETT
‘
} 2,121,536
AIRCRAFT SUSTAINING ROTOR
Original Filed Sep?. 14, 1935
4 Sheets-Sheet 4 '
INVENTOR
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2,121,536
angular displacement in the drag plane necessi
tates a greater. angular displacement about the
alpha pivot and also a displacement about the
delta pivot. The amount of damping both aero
dynamic and frictional is mainly dependent on
the velocity of the oscillations and is therefore
large only when the oscillations are rapid. "
It is not essential for the purposes of this in
vention that the delta pivot be a purely flapping
10 pivot, though this constitutes one convenient
and the drag links being yoke-shaped and inter
digitating as described in the speci?cation of Ben
nett‘and Hodgess- copending'British patent ap
plication No. 26,662 of 1934 (and in the corre- .
spending United States application, No. 40,386,
‘filed September 13, 1935).
'
The "rotor hub is shown at III, II and supports
f‘delta” or flapping pivot trunnions l2 on which
the inner ends I350,‘ “a: of drag links l3, I‘ are
rotatably mounted. In these ?gures the details 10
of the delta pivot bearings are not shown, as
arrangement; the delta pivot axis may, if de
sired, be inclined to the plane of rotation, i. e. these details form no part of the present?inven
the plane perpendicular to the rotational axis,
To the outer end of the drag links l3. ll are
for example as disclosed and claimed in the‘
bolted forked members I5, [6 carrying pins l1, 15v
15 copending application of Juan de la Cierva, Serial
l8 which constitute the axes of the alpha pivots
' No. 59,292, ?led January 15, 1936. Furthermore
either or both the delta and alpha axes may be on which are articulated blade root members I9,
other than perpendicular to the longitudinal blade 20 ?anged at l9m, 20a: for attachment to. corre
axes, so that either ?apping or drag movements sponding flanges Zlx, 221: formed on the root ends
20
of the blade spar sockets 2|, 22.
20 give rise to changes in blade pitch angle.
The orientation of the pivot axes will most
According to the present invention, the inclina
tion of the alpha axis to the ?apping plane may‘ easily be followed by reference to Fig. 4, the plane
be in either direction, 1. e. either forwardly or of which is perpendicular to the longitudinal
blade axis. In Fig. 4 the projection of the rota
rearwardly with respect to the direction of rota
tional axis on this plane is shown at 0-0 and 25
25
the projection of the delta axis at l~—l, while
In what follows, three embodiments of the in
tion.
tion.
-
,
'
.
'
the projection of the, alpha, axis ‘lies along the
vention are described with reference to the ac
companying drawings. In no case is the struc . section line 2-2. The outline of the rotor blade
is shown at b and the chord is substantially par
ture of the aircraft shown, as this may follow nor
30 mal practice for autorotative rotary winged air- ' allel to the delta axis l-l which in this case is 30
craft as described for example in Juan de la
a purely ?apping axis, being perpendicular to
Cierva’s British patent speci?cation No. 393,976
(or the corresponding United States application,
No. 645,985, ?led December 6, 1932); the rotor
the line 0--0.‘ The alpha axis, on the other hand,
is inclined at an angle of about 45° to the line
0—0, the inclination in this instance being for
wards and upwards with respect to the direction 35
35 hub is only indicated in outline as the invention
is solely concerned with the arrangement of the
of rotation indicated by an arrow R.
blade articulations.
Displacement of the blade about the alpha axis
is therefore resolvable into a dragv displacement
'
In the drawings:---
-
Fig. 1 is a view in side elevation of the rotor
40 hub of the ?rst embodiment of the invention.
Fig. 2 shows the blade articulation assembly as
viewed from below and in front, the showing be
ing partly in section taken along the line ‘2-4 of
Fig. 4.
45
in the direction l—| and a ?apping displacement
in the direction 0-0, the forward inclination of 46
the alpha axis in this case causing the blade to
rise as it moves back and vice versa. ’
‘
The amplitude of movement about the alpha
' pivot is limited by stop means consisting of a
‘
Fig. 3 is a view of the same from above and in , pin 23 secured between the jaws of the fork l5 45
front taken in the direction of the arrow 3 in
Fig. 4.
‘
Fig. 4 is a view in cross section taken along the
line 4-4 in Figs. 2 and 3.
50
/
-
Figs. 5 and 6 ‘illustrate the second modi?cation
of the invention; Fig. 5 showing the rotor blade
articulation as viewed from above and in front,
being partly shown in section taken along‘ the
line 5-5 of Fig. 6; and Fig. 6 being a view of the
55 same in cross section taken ‘along the line 6-6
of Fig. 5.
'
parallel to the alpha pivot I1 and engaging in a
slotted hole 24 formed in the blade root mem
ber
l9.
‘
I
-
The second ‘embodiment illustrated in Figs. 5
and 6 differs from the ?rst in that the blade ar 50
ticulation includes in addition to the alpha and
delta pivots a third .pivotvwhose axis lies in a
plane containing the longitudinal ‘blade axis and
the alpha, axis but is inclined at an acute angle
to the longitudinal blade axis so that blade dis 55
placements about this third axis give rise to
changes in "the pitch angle of the blade.
An arrangement of this kind is described in
Bennett’s copending United States Patent appli
ance with the invention; the plane of .Fig'. '7 be
ing the ?apping planeand that of ‘Fig. 8 the cation Serial No. 21,454 but with the “alpha" pivot
Figs. 7 and 8 are line'diagrams'illustrating the
motion of a rotor blade articulation in accord
oriented as a purely drag pivot; the functioning
of the third pivot to vary the blade pitch as de
of the invention; Fig. 9 being “asfvragmentary view ' ' scribed in said patent application is not detri
in elevation of a part of the ‘blade articulation; mentally a?ected by ‘inclining it together with
Fig. 10 being. a view of the blade articulation ‘ the alpha pivot at an acute angle to the plane
from below and behind, perpendicularly to the containing the rotational axis and longitudinal
drag plane.
-
-
Figs. 9 to 11 illustrate the third embodiment
longitudinal blade axis, partly sectioned along
the line Iii-l0 of Fig. 11; and Fig. 11 being a
view in section, taken along the line. |l—ll of
70
Fig. 10.
~
.
Referring to Figs. 1 to 4; this shows a two-‘
blade axis.
>
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'
As'before, a yoke-shaped drag link. I3 is shown
whose ends 13:1: articulate on the ‘divided axle of
the delta or ?apping articulation. The outer end 70
of the link I3 is ?anged at I30 for attachment .
ibladed rotor hub in which the “delta” pivot is to a ?anged lug 25 carrying the pivot pin 26 of
common to the two blades and is a purely ?apping. the alpha articulation. This pin articulates with
pivot, being divided into two halves mounted a forked link 21 by means of taper roller bearings
75 trunnionwise on the sides of the hub member 28, the lug 25 being inserted between the jaws. 75
v
‘of the forked member 21. The outer end of this
stop pin :1 carried by the lug at and projecting
member is formed as a bearing 29 in which is
on either side thereof into arcuate slots 38 formed
rotatable a stub axle member 30 ?anged at 30::
for attachment to the root ?ange Zia: of the
blade spar M. The bearing assembly 29, 30, thus
constitutes the third blade articulation pivot,
whose axis is at an acute angle to the longitudinal
in the jaws t5.
blade axis.
'10
3
‘
’
'
The orientation of the alpha and delta axes
will most easily be followed by reference to Fig. 6,
the plane of which is perpendicular to the longi
‘
The link {it terminates outwardlyiFiglO) in‘
a stub axle 38 on which is rotatably mounted by
means of taper roller bearings M a housing at
integral with the blade root socket t2, the bear
ings being retained by a ring member at secured
to the housing iii and vserving to transmit the
10
centrifugal .force of the blade to the bearings.
The pivot assembly 39, dd, ti constitutes the -
tudinal blade. axis and on which the projections
alpha pivot of the blade articulation, and its axis
of the rotational axis, the delta axis and the
alpha axis are respectively 'indic‘atedvby the lines
15 0-0, 1-1 and 5—5, the blade pro?le outline be
ing indicated in chain dotted lines at b. The
a-a. is inclined at an acute angle to the longi
tudinal blade axial-i (see Fig. 10), so that
direction of rotation is shown by an arrow B. and
in this instance the alpha axis is inclined back
wardly and upwardly with respect tothe line 0—0
20 at an angle of about 45°, so that displacement of
the blade about the alpha axis is resolvable into
a drag displacement in the direction 1—1 and a
‘ ?apping displacement in the direction 0+0.
blade displacements‘about the alpha axis involve 15
variation of the blade pitch angle.
Reference to Fig. 11 shows that the projection
of the alpha axis on the plane containing the
rotational axis and perpendicular to the/?apping
plane is inclined backwardly and upwardly with
respect to the rotational axis at an acute angle,
it being premised that in the position shown in .
all the ?gures the blade axis i-ll is perpendicular
Figs. 7 and 8 illustrate diagrammatically the "to the rotational axis, so that the plane of pro
movement of the blade about the pivot axes. In jection above referred to is parallel to the plane 2%
these ?gures the position of the delta pivot axis of, Fig. 11, on which the projections of the rota
is shown at O and the alpha pivot axis is shown at tional axis, the alpha axis and the delta axis are
A, A1,‘- A2. The mean position of the blade is respectively indicated by the lines d—-@, m—ib '
shown in both ?gures at O, A, B and the positions and d—-d. In Fig. 11 the blade pro?le is indicated
atb, the chord being substantially parallel to'
3d resulting from displacing the blade in either di
rection about the alphaaxis are shown at 0, A‘, the delta axis. It will further be seen from Fig.
B1 and 0, A3, B3111 Fig. 7 and O, A, B1 and O, A, - 10 that the intersections with the longitudinal
B2 in Fig. 8 in which view the points A, A1, A2 blade axis Z—Z oi’ the alpha axis H and of, the '
delta axis, whose projection isshown at‘ d—d in
coincide.
If the blade is displaced about the alpha pivot Fig. 10, are substantially o?set from one another.
35
through a small angle the angular displacement ‘The blade articulation shown in Figs. 9—11 there
is resolvable into a displacement in the drag plane fore operates in the manner described 'with ref
represented in Fig. 8 by the angle B, A, B1 and a erence to Figs. 7 and 8, the inclination of the
displacement in the ?apping plane represented alpha axis M at an acute angle to the blade .
by the angle 0, N, B1 in Fig. 7. Now, if the blade axis l-l serving only to superimpose on the ?ap ii iii
performs an oscillation in the dragplane, there ping and drag displacements a change of pitch
will be no tendency, other things being equal, for angle, without substantially modifying ‘the > '
the centre of inertia of the blade, indicated at changes of con?guration described with refer-~
I in Fig. 7, to leave the drag plane, and’ the ?ap
ence to Figs. 7 and 8, at least for small displace;
ping displacement O, A‘, B1 or 0, A”, B3 will be ments about the alpha axis. Similarly the in db
compensated by a displacement of the drag link clination of the alpha axis H to the plane con- '
about the delta axis 0 through an angle indicated taining the rotational axis t-t and the longi
in Fig. 1 at A, O, A1 or A, 0, A2. Therefore an tudinal blade axis [-4 does not substantially af
oscillation of the blade in the drag plane from fect the functioning of the inclination at an acute
B1 to B2 and back again is necessarily accom
panied by rocking of the blade in the ?apping
plane about its centre of inertia from A‘, B1 to
A”, Brand back again. Further, the rocking
movement in the flapping plane about the centre
55 of inertia provides the aerodynamic damping of
the drag oscillation.
V
,
In the third embodiment, shown in Figs. 9 to
11, the alpha pivot axis of the blade articulation.
is inclined to the longitudinal blade axis so that
80 movements about the alpha pivot give rise to
changes in the pitch angle of the blade as de-‘
- scribed for instance .in copending Cierva United
States Patent application Serial No. 738,349. In
Fig.‘ 9 whose plane is parallel to the ?apping
65 plane, the rotor hub is shown fragmentarily at
31 and incomporates a. ?at pivot lug 32 lying in
the ?apping plane and carrying a pin 33 forming
the axle of the delta pivot, which in'this instance
‘is a purely flapping pivot, its axis d being per
pendicular to the plane of Fig. 9.
.
The articulating link 34 terminates inwardly
in a forked en-d,’bored at 36 to receive the delta
pin 33, on which the link is rotatable for ?ap
ping, the. lug 32 fitting between the jaws 35 of
Flapping movement is limited 'by a
75 the fork.
angle of the axes a—a and l-l in producing all“
the’results ?owing from automatic change of
pitch with displacement in the drag plane de- I
scribed in thesaid copending application Serial.
No. 738,349.
'
What! claim is:—,
‘
r.
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55
1: An- aircraft-sustaining rotor ‘comprising a
generally upright hub, a plurality of blades ex
tending outwardly therefrom and normally posi
tioned with respect thereto at an autorotational
incidence, and for each blade a mounting link,
a ?apping or-delta pivot approximately inter
' secting the longitudinal axis of the blade and ar
ticulating said link to the hub for movement of
the link generally in a plane containing the hub
axis, and a drag or alpha pivot approximately
intersecting the longitudinal axis of the blade
and articulating the blade to said link for oscil
lation with respect thereto; the axis of said alpha
‘pivot, projected on a plane containing the hub
axis but perpendicular to the longitudinal, axis 70
of the blade, making a substantial oblique angle
wth relation to the plane containing the hub
axis and the longitudinal blade axis and also
with relation to the general plane of the blade
when the latter is in substantially true radial 75
2,121,580
‘position, 'whereby'oscillation of the blade on the
axis being in an upward and forward direction
alpha pivot' with relation to the link is com
pounded of an appreciable movement of the
with respect to the direction of rotation of the
rotor.
blade in the plane of rotation and an appreciable
movement in the plane transverse thereto.
2. An aircraft sustaining rotor comprising a
generally upright hub, a plurality _of blades ex
5. An aircraft sustaining rotor comprising a
generally upright hub, a plurality of blades ex
tending'outwardly therefrom and normally posi
tending outwardly therefrom and normally po
tioned with respect thereto at an autorotational
incidence, and for each blade a mounting link, a"
?apping or delta pivot approximately intersect
ing the longitudinal axis of the blade and articu 10
lating said link to the hub for movement of-the
link generally in a plane containing the hub axis,
and a drag or alpha pivot approximately inter
the link generally in a plane containing the hub secting the longitudinal axis of the blade and
15 axis, and a drag or alpha pivot approximately articulating the blade to said link for voscillation 15
intersecting the longitudinal axis of the blade at with respect thereto; the axis of ‘said alpha pivot,
‘a point radially off set from the point of inter
projected on a plane containing the hub axis but
section of the delta pivot axis and the longitudi- ' perpendicular to the longitudinal axis of the
nal blade axis and articulating the blade to said blade, making a substantial oblique angle with
link for oscillation with respect thereto; the relation to the plane ‘containing the hub axis and 20
axis of said alpha pivot, projected on a plane‘ the longitudinal blade axis and also with relation
containing the hub axis but perpendicular to the to ‘the general plane of the blade when the latter
is in substantially true radial position, said,
longitudinal axis of the blade, making a sub
stantial oblique angle with relation to the plane oblique inclination of the alpha axis being in an
containing the hub axis and the-longitudinal upward and rearward direction with respect to
blade axis and also with relation to the general
the direction of rotation of the _rotor.
plane of the blade when the latter is in sub
6. An aircraft sustaining ' rotor comprising a
stantially true radial position, whereby forces generally upright hub, a plurality of blades ex
acting to displace the blade in a direction con
tending outwardly therefrom and normally posi
tained within the general path of rotation about tioned with respect thereto at an autorotational 30
sitioned with respect thereto at an autorotational
10 incidence, and for each blade a mounting link,
a flapping or delta pivot approximately inter
secting the longitudinal axis of the blade and
articulating said link to the hub for movement of
the alpha axis also tend to produce an oscilla
tion about the delta axis.
?apping or delta pivot approximately intersect
‘ 3. An aircraft sustaining rotor comprising a
ing the longitudinal axis of the blade and articu
generally upright hub, a plurality of’ blades ex
tending outwardly therefrom and normally po
lating said link to the hub for movement of the
link generally in a plane containing the hub axis, 35
sitioned with respect thereto at an'autorotational
incidence, and for each blade a mounting link, a
?apping or delta pivot approximately intersect
ing the longitudinal axis of the blade and articu-'
and a drag or alpha pivot approximately inter
secting the longitudinal axis of the blade and
articulating the blade to said link for oscillation
with respect thereto; the axis of said alpha pivot,
lating said link to the hu ) for movement of the
projected on a plane containing the hub axis but
link generally in a plane containing the hub axis,
and a drag or alpha pivot approximately inter
secting the longitudinal axis of the blade and
articulating the blade to said link for oscillation
perpendicular to the longitudinal axis of the blade,
making a substantial oblique angle with relation
with respect thereto; the axis of said alpha pivot,
55~
incidence, and for each blade a mounting link, a
to the plane containing the hub axis and the lan
gitudinal blade axis and also with relation to the
general plane of the blade when the latter is in 45.
projected on a plane containing the hub axis but
substantially true radial position, said alpha axis
perpendicular to the longitudinal axis of the
blade, making a substantial oblique angle with
relation to the plane containing the hub axis
further being inclined in a radial direction.
7. An aircraft sustaining rotor comprising a
generally upright hub, a plurality of blades ex
and the longitudinal blade axis and also with
tending outwardly therefrom and normally posi 50".
relation to the general plane of the blade when
the latteris in substantially true radial position,
incidence, and for each blade a mounting link, a
said oblique angle beingin the neighborhood of
?apping or delta pivot approximately intersecting
45°.
the longitudinal axis of the blade and articulat
ing said link to the hub for movement of the link 55,
generally in a plane containing the hub axis, and
a drag or alpha pivotapproximately intersecting
the longitudinal axis of the blade and articulating
the blade to said link for oscillation with respect
thereto; the axis of said alpha pivot, projected on
a plane containing the hub axis but perpendicular
to the longitudinal axis of the blade, making a
substantial oblique angle with relation to the
4. An aircraft sustaining rotor comprising 'a
generally upright hub, a plurality of blades ex
tending outwardly therefrom and normally posi
tioned with respect thereto at an auto rotational
incidence, and for each blade a mounting link, a
60 ?apping or delta pivot, approximately intersect
ing the longitudinal axis of the blade and articu
lating said link to the hub for movement of the
link generally in a plane containing the hub
axis, and a drag or alpha pivot approximately
intersecting the longitudinal axis of the blade
and articulating the blade to said link for oscil
tioned with respect thereto at an autorotational -
plane containing the hub axisand the longitudinal
blade axis and also with relation to the general
plane of the blade when the latter is in substan
lation with respect thereto; the axis of said alpha tially true radial position, said alpha axis further
pivot, projected on a plane containing the hub being inclined upwardly‘ and outwardly so as to
axis but perpendicular to the longitudinal axis of -make an acute angle with the longitudinal axis of
70'
70 the blade, making a substantial oblique angle the blade.
with relation to the plane containing the hub ,
8. An aircraft, sustaining rotor comprising a.
axis and the longitudinal blade axis and also generally upright hub, a plurality of blades ex
with relation to the general'plane of the blade tending outwardly therefrom and normally posiwhen the latter is in substantially true radial tioned with respect thereto at an autorotational
incidence, and for each blade a mountinglink, a 75,
75 " position, said oblique inclination of the alpha
2,121,586_
5
_
_
‘ ?apping or delta ‘pivot approximately intersecting
.secting the longitudinal axis of the blade at an
the longitudinal axis of the blade and articulating
acute angle whereby the blade pitch varies with
oscillation about said third pivot, said third-pivot
' said link to the hub for movement of the link gen
erally in a plane containing the hub axis, and a having its axis extending generally upwardly and a
5 drag or alpha pivot. approximately intersecting the > outwardly with respect to the longitudinal axis of
longitudinal axis of the blade at a point radially the blade. '
11. An aircraft sustaining rotorcomprising a
offset from the point of intersection of the delta
pivot axis and the longitudinal blade axis and generally upright hub, a plurality of blades ex
articulating the blade to said link for oscillation tending outwardly therefrom, and normally posi
10 with respect thereto; the axis of said alpha pivot, tioned with respect thereto at an autorotational 10
projected on a plane containing the hub axis but incidencaand for each blade a mounting link, a
?apping or delta pivot approximately intersecting
' perpendicular to the longitudinal axis of the blade,
making a substantial oblique angle with relation, the longitudinal axis of the blade and articulating
said link to the hub for movement of the link gen
to the plane containing the hub axis and the lon
15 gitudinal blade axis and also with relation to the erally in a plane containing the hub axis, and a
general plane of the blade when the latter is in drag or alpha pivot approximately intersecting
substantially true radial position, said alpha axis the longitudinal axis of the blade and articulating
the blade to said link for oscillation with respect
further bein'g inclined in a radial direction. '
9. An aircraft sustaining rotor comprising a thereto; the axis of said alpha pivot, projected on
a plane containing the hub axis but perpendicu 20
2% generally upright hub, a plurality of blades ex
lar to the longitudinal axis of the blade, making a'
tending outwardly therefrom and normally posi
tioned with respect thereto at an autorotational , substantial oblique‘ angle with relation tov the
incidence, and for each blade a mounting link, a plane containing the hub axis and the longitudinal
?apping or delta pivot approximately intersecting _ blade axis and also with relation to the general
2d the longitudinal axis of the blade and articulating plane of the blade when the latter is in substan 25
said link to the hub for movement of the link gen
erally in a plane containing the hub axis, and a
drag or alpha pivot approximately intersecting
the longitudinal axis of the blade at a point radi
to ally offset from the point of intersection of the
delta pivot axis and the longitudinal blade axis
and articulating the blade to said link for oscilla
tion with respect thereto; the axis of said alpha
pivot, projected on a plane containing the hub
an axis but perpendicular to the longitudinal axis of
' the blade, making a substantial oblique angle with
relation to the plane containing the hub axis and
the longitudinal blade axis and also with relation
to the general plane of the blade when the latter is
40 in substantially true radial position, whereby
forces acting to displace the blade in a direction
c contained within the general path of rotation
abput the alpha axis also tend to produce an oscil
lation about the delta axis, and a third pivot inter
45 posed between the blade and the‘alpha pivot and
intersecting the longitudinal axis of the blade at
an acute angle whereby the blade pitch varies with
oscillation about said third pivot.
l0. An aircraft sustaining rotor comprising a
50 generally upright hub, a plurality of blades ex
tending outwardly therefrom and normally posi
tially true radial- position, whereby oscillation of ,
the blade on the alpha pivot with relation to the
link is compounded of an appreciable movement of
the blade in the plane of rotation and an appreci
able movement in the plane transverse thereto, 30.
the axis of the delta pivot being positioned
intersect the hub axis.
.
v
12. An autorotatable sustaining rotor for air
craft, comprising a hub, a blade, and mechanism
for articulating the blade upon the hub includ
ing: a pivot whose axis is substantially parallel
to the blade chord and perpendicular to' the
longitudinal axis of the blade, a pivot whose axis
is substantially perpendicular to the longitudinal
axis of the blade and oblique to the blade chord, 4:0
and a pivot whose axis is oblique to the plane of
the blade, to its chord, and to its longitudinal
axls.
'
13. An autorotatable sustaining rotor for air
craft, comprising a hub, a blade, and mechanism 45
for articulating the blade upon the hub includ
ing; a pivot whose axis issubstantially parallel
to the blade chord and perpendicular to the
longitudinal axis of the blade, a pivot whose axis
is substantially perpendicular to the longitudinal 50
axis of the blade and oblique to the blade chord,
and a pivot whose axis is oblique to the plane of
the blade, to its chord, and to its longitudinal
?apping or delta pivot approximately intersecting axis, each of said pivot axes approximately in
the longitudinal axis of the blade and articulating tersecting the longitudinal axis of the blade and 55
said link to the hub for movement of the link gen- ~ being spaced apart from each other, in the order
erally in a plane containing the hub axis, a drag named, in the outward radial direction.
14. In an aircraft sustaining rotor, a hub, an
or alpha pivot approximately intersecting the lon
gitudinal axis of the blade at a point radially autorotative blade, and pivot mechanism mount
oiTset from the point of intersection of the delta ing the blade on the hub including a pivot'axis 60
pivot axis and the longitudinal blade axis and extended at an oblique'angle to a plane con
articulating the blade to said link for‘oscillation taining the rotor axis and the longitudinal blade
with respect thereto; the axis of said alpha pivot, axis and a second and non-parallel pivot axis
extended at an angle to a plane perpendicular
projected on a plane containing the hub axis but
perpendicular to the longitudinal axis of the blade, to the axis of the rotor the inclination being up
making a substantial oblique angle with relation wardly and outwardly with respect to the blade
axis, whereby the blade has comp'ound oscil
to the plane containing the hub axis and the 1on
gitudinal blade axis and also with relation to the lating and pitch-varying movements which are
general plane of [the blade when the latter is in aerodynamically damped.
15. In an aircraft sustaining rotor, a hub, an
substantially true radialwposition, whereby forces
tioned with respect thereto at an autorotational
incidence, and for each blade a mounting link, a
55
""r
59
65
70
-acting to displace the blade in a direction con
autorotative blade, and pivot mechanism mount
ing" the blade on the hub including a pivot axis
the alpha axis also tend to produce an oscillation - extended at an angle to a plane perpendicular to
about the delta axis, and a third pivot interposed the‘ axis of the rotor the inclination being up
tained within the’general path of rotation about
75 between the blade and the alpha pivot and inter
wardly toward the trailing edge of-the blade and
2,121,536
a second pivot axis extended at an angle to a blade axis at'the outer side of the pivot rear
.
plane perpendicular to the axis of the. rotor the wardly oi’ the blade axis.
inclination being upwardly and outwardly with »
19. In an aircraft sustaining rotor, a generally
respect to the blade axis.
upright hub, an autorotatable blade with its
16. In an aircraft sustaining rotor, an upright longitudinal axis extending generally radially
hub, a blade normally positioned on the hub at from said hub, mechanism mounting said blade
autorotational incidence and having its longitu
on said hub for oscillation relative thereto in- '
dinal axis extending generally radially from the eluding a pivot device the axis of which, when
hub, and means articulating the blade to the hub viewed in plan, makes an acute angle with the
10 for oscillations with respect thereto in ?ight in
blade axis at’ theouter side of the pivot rear 10
cluding a plurality of pivot devices, one such wardly of the blade axis-and, when viewed along
device providinga pivot axis for the blade which, ' the blade axis, is oblique to the axis of the hub
when viewed along said blade axis, is at an acute and is obliquely inclined relative to the blade
angle to the blade chord and to the rotor axis; chord upwardly and rearwardly with respect to
15 and another such pivot device being out of
the direction of rotation oi.’ the blade.
15
parallelism with that just mentioned and pro
20. In an aircraft sustaining rotor, a generally
viding in large part for ?apping movement of the upright hub, an autorotatable blade with its
blade, the said two pivot devices being spaced longitudinal axis extending generally radially
‘apart in. a radial direction relative to the rotor from said hub, and mechanism mounting said
20
blade on said hub for oscillation relative there 20
‘
17. In an aircraft sustaining‘ rotor, a generally .to including two pivots the axes of which, when
upright hub, an autorotatable blade with its projected on a plane perpendicular to 'said blade
longitudinal axis extending generally radially axis, intersect each other, and at least one of
from said hub, and mechanism mounting said said pivot axes isoblique to the rotor axis and
25 blade on said hub for oscillation relative thereto to the blade chord.
25
axis.
including a pivot device the axis of which, when
viewed along the blade axis, is oblique to the
axis of the hub and is obliquely inclined relative
to the blade chord upwardly and rearwardly with
30 respect to the direction of rotation of the blade.
‘
18. In an aircraft sustaining rotor, a generally
upright hub, an autorotatable blade with its
longitudinal axis extending generally! radially
from said hub, and mechanism mounting said
35 blade on said hub for oscillation relative thereto
21. An autorotatable sustaining rotor for air
craft, comprising a hub, a blade,‘ and mechanism
for articulating the blade upon the hub includ
ing: a pivot whose axis is substantially parallel
to the blade chord and perpendicular to the 30
longitudinal axis of the blade, a pivot whose axis
is substantially perpendicular to the longitudinal
axis of the blade and oblique to the blade chord,
and a pivot whose axis is oblique to the plane of
the blade, and to its longitudinal axis.
including a-pivot device the axis of which, when
’ viewed in plan, makes an acute angle with the
JAMES ALLAN JAMIESON BENNETT.
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