United States Patent 19 3,976,265

Doolittle 45 Aug. 24, 1976

54 SEMIBUOYANT COMPOSITE AIRCRAFT
(75) Inventor: Donald B. Doolittle, Hockessin, Del. 57) ABSTRACT
73 Assignee: All American Industries, Inc., Various modifications are disclosed of the composite
Wilmington, Del. aircraft, which is the subject of U.S. Pat. No.
22 Filed: Dec. 23, 1974 3,856,236 by this same inventor. The control console
is supported from the center of the upper rotating bal
{2t Appl. No.: 535,417 loon sphere instead of its south pole to reduce the pe
trafi riodic motion of the console about its point of attach
Related U.S. Application Data ment to the sphere. The console is ST- from the
(63) Continuation-in-part of Ser. No. 357,636, May 7, center of an inner framework through a tapered in
1973, Pat. No. 3,856,236. dentation in the bottom of the sphere. A lift command
control system determines the angle of attack of each
52 U.S. Cl....................................4iii., wing about the periphery of the sphere to provide the
5 Int. C.’.......... B64c 37/02 force required to generate movement of the sphere in
(58) Field of Search m 2442.5 7. 1, 25 a preselected direction. If the wing experiences a gust,
244/26, 27 28. 97,467 4 15 156 1 58 the force reaction compels the wing to seek a different
is a a r1 1 f angle of attack to keep the new force in balance with
56) References Cited the command force exerted by the control on the wing
to automatically provide gust control. A pneumatic lift
UNITED STATES PATENTS command control system is illustrated. The altitude of
1,682,96 | 9, 1928 Hall ...................................... 244/97 the aircraft is controlled by maintaining the gas pres
l,838,248 l 21193 l Bourland.......................... 24.4/26 X sure at constant temperature by heat, such as obtained
2,427,939 9, 1947 Woods. ..., 46f 58 X from the engine. Other variations for reducing drag
38. '': plant • . . . . . . . . . . . . . . . . . . . . . . . . . .2 it's include: boundary layer control of air pressure about
3,856.236 21974 5 title ----- - - - - - - - --- - ------ --- 2. the sphere to overcome the Magnus effect enclosing
sal - 1 1- - - - 1st B 1 it 1 v. V. L. L. V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the sphere in an envelope, which does not rotate rela

FOREIGN PATENTS OR APPLICATIONS tive to the air, flattening the sphere and driving it by
191445 lf 1923 United Kingdom................... 244/26 auxiliary engines instead of tilting it or by applying
cone-shaped sections to one hemisphere and translat
Primary Examiner-Duane A. Reger ing a substantially horizontal position.
Assistant Examiner-Barry L. Kelmachter
Attorney, Agent, or Firm-Connolly and Hutz 8 Claims, 10 Drawing Figures

A .

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U.S. Patent Aug. 24, 1976 Sheet 3 of 5 3,976,265
U.S. Patent Aug. 24, 1976 sheet 4 of 5 3,976,265
U.S. Patent Aug. 24, 1976 Sheet 5 of 5 3,976,265

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1 2
FIG. 4A is a cross-sectional view taken through FIG.
SEMBUOYANT COMPOSITE AIRCRAFT 4 along the line 4A-4A;
FIG. 5 is a three-dimensional view of one of the gird
CROSS-REFERENCE TO RELATED ers of the composite aircraft shown in FIGS. 3 and 4;
APPLICATIONS, IF ANY FIG. 6 is a top plan view of wing and partial portions
This application is a continuation-in-part of copend of the balloon chamber of the composite aircraft shown
ing commonly assigned application for U.S. Letters in FIGS. 3 and 4;
Patent Ser. No. 357,636, filed May 7, 1973, by this FIG. 7 is a cross-sectional view taken through FIG. 6
same inventor, issuing as U.S. Pat. No. 3,856,236. O
along the line 7-7; and
FIG. 8 is a cross-sectional view in elevation taken
BACKGROUND OF THE INVENTION through a portion of the control console of the aircraft
A composite aircraft capable of lifting and transport shown in FIGS. 3 and 4.
ing extremely heavy weights over limited distances at DESCRIPTION OF THE PREFERRED
relatively slow speed is described in U.S. Pat, No. 15 EMBODIMENTS
3,856,236. Heavy wind gusts interfere with the flight of
such an aircraft and temperature variations vary the (FIGS. 1, 1A and 2)
lifting effect of the lighter-than-air gas. The control In FIG. is shown a composite aircraft 10, lifting and
console slung below the bottom of the lifting sphere is transporting an extremely heavy tree 12, directly from
also subject to disruptive periodic swinging. An object 20 forest 15. The ability of aircraft 10 to lift and transport
of this invention is to provide a stable control and rig a complete untrimmed tree, branches and all, makes it
ging for such a composite aircraft. possible to selectively pluck large trees from the midst
SUMMARY of a forest without cutting erosion promoting roads and
swaths through the forests.
In accordance with this invention the control system 25 Aircraft 10 includes a large balloon chamber 14 con
for adjusting the angle of attack of the wings is of the taining within balloonettes 16 a light-than-air gas such
lift command type, which establishes a desired aerody as helium. Chamber 14 is distended in substantially
namic force to be obtained from each wing. If the wing spherical shape by a slight air pressure provided by a
experiences a gust, the change in aerodynamic force blower or compressor (not shown). Chamber 14 can
compels the wing to seek a different angle of attack for also be comprised of a single teardrop shaped balloon
regaining the predetermined force commanded by the configuration, but the spherical form reduces drag and
control system. A pneumatic lift command control facilitates maneuvering. The outer skin of spherical
system controls the angle of attack through a pneu chamber 14 is for example made of a relatively strong
matic cylinder and piston drive whose position is con fabric, such as nylon. Balloonettes 16 are for example
trolled by valving actuated by a helicopter swash plate 35 made of an elastomer coated Dacron or of Mylar film.
control. The valving may rotate with the balloon cham Dacron is the trademark of E. I. du Pont de Nemours &
ber and extend into the control console. The stability of Co. of Wilmington, Delaware for a synthetic fiber made
the aircraft is enhanced by a strong girder network by the combination of dimethyl terephthalate and eth
emanating substantially from the center of the balloon ylene glycol. Mylar is the trademark of the aforemen
chamber which has a tapered bottom indentation ex 40 tioned company for a highly durable, transparent water
tending substantially to its center. The console is at repellent fiber of polyethylene terephthalate resin. Bal
tached substantially to the center of the chamber by a loonettes 16 are inflated to slightly less than full spheri
long suspension beam and a rotatable joint. The long cal volume, such as 90% thereof, to allow for tempera
effective suspension for the console from the relatively ture and pressure fluctuation.
stable center of the balloon chamber minimizes peri 45 A strong mast 18 of structural material such as steel
odic swaying motion of the console. The lifting force of or duralumin is mounted within chamber 14 at its verti
the ligher-than-air gas in the balloon chamber is effi cal axis. Wing spars 20 are joined by connectors 22 to
ciently controlled by applying controlled heat to the the middle of mast 18 for supporting the four (4) wings
gas from the propulsion engines. 24 which extend substantially horizontally about cham
50 ber 14. Rotatable couplings 26 connect wings 24 to
BRIEF DESCRIPTION OF THE DRAWINGS spars 20 to permit their angle of attack to be adjusted
Novel features and advantages of the present inven for individually varying their lift. Control of the angle
tion will become apparent to one skilled in the art from of attack is provided by a linkage diagramatically illus
a reading of the following description in conjunction trated by broken lines 28 within the interiors of mast 18
with the accompanying drawings wherein similar refer 55 and spars 20. This control is actuated by a helicopter
ence characters refer to similar parts and in which: type cyclical control diagramatically illustrated by
FIG. 1 is a pictorial view partially broken away of one block 30 in control console 40, which is hung by a
embodiment of this invention lifting an entire tree from swivel bearing 42 below the bottom of mast 18 extend
a forest: ing below chamber 14. Swivel bearing 42 may also be
FIG. 1A is an enlarged view in elevation of the sus O described as a rotatable or universal joint 42. The cycli
pension between balloon chamber and cab of the em cal control is, for example, as described in Aerodynam
bodiment shown in FIG. 1; ics of the Helicopter by Alfred Gessow and Garry C.
FIG. 2 is a theoretical diagram of lateral speed and Myers, Jr. published by the Frederick Ungar Publishing
load capacities of the embodiment shown in FIG. l; Co., New York, New York, U.S.A., Copyright 1952
FIG. 3 is a top plan view of another composite air 65 and republished 1967, pages 22-28, or Helicopter Engi
craft which is another embodiment of this invention; neering by Raymond A. Young, published by the Ro
FIG. 4 is a front view in elevation of the composite nald Press Company, New York, Copyright 1949,
aircraft shown in FIG. 3; pages 8-13.
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Control console 40 is for example the cabin and ever, since ability to operate under reasonable wind
gyroscopic stabilizer 44 a of helicopter, less the propul conditions must be considered, speeds of 30 to 50 mph
sion engines and rotor blades. Wings 24 are supported are considered as essential to achieve an economically
against upward and downward reaction forces by a useful heavy lifter. Since the balloon chambers will be
series of guy wires 46 connecting spars 20 to mast 18 the major source of aerodynamic drag, the C of this
within balloon chamber 14. The external wings 24 are structure is the major factor in achieving acceptable
also supported by guy wires 48 extending outside of translational flight performance. Theoretical speeds
balloon chamber 14. The relatively slow linear speed of and load capabilities of aircraft 10 are described in
wings 24 minimizes the drag caused by outer guy wires FIG. 2.
48 and makes it insignificant. 10 The control cab and load sling are attached at the
Thrust motors 50, such as turboprop engines, are south pole by a suspension 52 including a self-aligning
mounted on wings 24 for rotating them about mast 18 bearing which will allow the cab to stay stationary
and the vertical axis of rotation of aircraft 10. Turbo under the influence of a tail rotor stabilizer 44 as the
prop engines are advantageous for this service because balloon and blades rotate, and allow the sling tension
of their smooth dependable and reliable operating 5 member to remain vertical as the balloon and blades tilt
characteristics with relatively good fuel economy and to achieve translation. A spherical roller bearing may
efficient aerodynamic performance. be used here if it has sufficient angular tolerance i.e. 20
Aircraft 10 (without a sling load) is at all times buoy to 30%. A suspension 52 including motor 54 and spur
ant and landing involves mooring. As the size increases, gear 56 mounted fixed in torque on the control cab 40
the maximum wind in which the vehicle can be moored 20 and a ring gear 58 on the balloon chamber 14 through
simply by a single point at the bottom of the control cab universal joint 42 would allow the operator to retain
or by its lifting sling increases. All vehicles large the fixed cab heading without using tail rotor 44 as the
enough to be of economic value (i.e., over 20,000 lbs. balloon rotates above. Motor 54 drives spurgear 56 and
sling load) can be moored in this fashion in all normal cab 40 about ring gear 58 through rotating bearing 60
wind conditions (i.e. up to 20-40 mph depending on 25 which angularly insolates balloon chamber mast 18
size). For conditions beyond the single point mooring from helicopter support mast 18A.
capability, facilities must be prepared for by more com Slip rings, and possibly rotatable couplings for air
plicated mooring systems. Unlike an airship which re and/or hydraulics will be required to transmit control
quires swinging room, the spherical aircraft is non signals from cab to balloon-rotor. Reliability and re
directional, but is also consequently of higher drag. It 30 dundancy in the detail design of this feature will be
appears, however, that it should be in general much extremely important.
easier to handle and moor because of its nondirectional Fuel will be carried in the lower part of cab to obtain
characteristics. as much statically stable moment as possible during
Ferrying over long distances does not appear practi unloaded flight.
cal and it would probably be better in small sizes to 35 Excessive static stability during loaded flight caused
knock down and ship. A trip of a few hundred miles by the sling load - buoyant force couple may be a con
could be made with proper attention to weather. The trol problem but preliminary calculations show it to be
problem is not endurance of the vehicle but endurance solvable by cyclic pitch control fore and aft with the
of the crew since it would be possible to sling carry fuel sling attached at the south pole. If the performance
for many hours (possibly days) flight. In all uses there 40 penalty for this control proves too great, the structural
will be wind conditions where flight operations should penalty of moving the slings and cab self-aligning joint
be studied in detail for each proposed use. toward the center of the sphere can be investigated.
One limitation of aircraft 10 may be its inability to The sling itself is a relatively simple tension member
operate when the load is exactly equal to the aerostatic 45
with hooks, releases, grabbers, etc., dictated by the use
lift. Under this condition the vehicle is neutrally buoy of the vehicle and will not be treated in detail herein.
ant and there is no aerodynamic thrust available to be The outer skin of the balloon is pressurized with an
vectored for translation unless the thrust vector is made air blower to maintan a small pressure differential to
parallel to the earth. Making the balloon-rotor rotate maintain the shape of the sphere against any expected
90 does not seem practical for most operations. Uses dynamic pressure. The balloonettes are inflated to less
which involve a loaded trip in on direction and an SO than full spherical volume (assumed 0.9 in perform
empty trip back, or fully loaded in both directions are ance calculations) to allow for variation due to temper
more suitable to the flight characteristics of the aircraft ature and altitude.
10. Some thought has been given to the possibility of Aircraft 10 offers several interesting safety features
vertical tacking if forced to operate with load equal to compared to a conventional helicopter. Since the en
aerostatic lift. In this mode the vehicle would climb 55 tire structure is buoyant with the "hold down' load
(i.e. at 45°) and the drag would provide force for the being the sling cargo or in the absence of cargo the
rotor to work against. Then when halfway to destina negative lift of the rotor, loss of power results in falling
tion, a corresponding descent would be undertaken. up. When loaded, aircraft 10 has such a light disc load
Difficulty would still be encountered in holding a hov ing that autorotative descent is at parachute values,
ering station in a wind. This condition would, therefore, 60 allowing a machine fully loaded to land its cargo and
probably be amended by adjustment of static lifting remain attached to it, as an anchor. However, since
force. aircraft 10 is multi-engined and since the full load
Because of the required size of the central balloon hover power is less than half of that needed to assure a
dictated by the static lift required, forward speed of the reasonable cruising speed, there is little chance of the
aircraft will be quite limited as compared with the con 65 requirement for a power off descent or danger of un
ventional helicopter. This fact limits this vehicle to controlled ascent. Features for gas valving could be
missions where efficient static lifting ability is of prime incorporated but are not considered essential for a
importance and translation velocity is secondary. How multi-engined machine and might upon analysis be of
 3,976,265
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more hazard than good. Because of size, direct control from there to the control cab through a rotating valve
for both collective cyclic pitch does not seem to be system at the cab-balloon rotating joint. This may be
practical, therefore, care in design and sufficient re either full flow or a servo flow depending on size of the
dundancy in the power pitch controls must be incorpo vehicle and control power requirements. Direct opera
rated. The lifting gas in separate balloonettes (eight for 5 tion is desired for reliability. Electrical operation of
a four wing system) gives good redundant safety in this servo valves could also be used with slip rings replacing
area. The excellent apparent protection against this the rotary valve system at the rotating joint.
machine falling should be of special interest in opera The cyclic lift control will be connected to a fore and
tion in forest areas where fire is a great hazard and in aft and an athwartship control valve. The fore and aft
populated areas. O valve is operated by sidewise movement of the cyclic
On the negative side, the limited speed of aircraft 10 lift control and controls lift in the right and left semi
makes operation in high winds a problem and possibly circles of the rotor wings.
hazardous. Dropping of sling cargo as a safety measure For an aircraft 10 capable of transporting a 100,000
in remotic areas should be considered, but with all other lb. payload, four blades would be used on a balloon
redundancies of the vehicle, there is little probability 15 approximately 150 ft. in diameter. Each blade (actually
this will be required. a symmetrical aircraft wing of completely standard
Operation of engines under moderate G's does not construction) is approximately 125 ft. long by 18 ft.
appear to be a serious problem. Both turboprop and wide and mounts a turboprop engine.
reciprocating engines should not have any major prob Rotational speed of aircraft 10 in this 100,000 lb
lem at 10 g or under. Centrifugal acceleration can be payload configuration is about 10 RPM. This will pro
kept as low as 5g if required without compromising the duce a maximum gload of 6.2 at the tip of the wing,
performance seriously. In the final analysis, a qualifica with considerable lower and fully acceptable G forces
tion run on a centrifuge arm can be made to proof test experienced by the engines. Forward speed will be in
the engine selected under actual G conditions. the neighborhood of 35 to 40 MPH using a maximum
The propeller should be of a constant speed variable 25 of 5,000 horespower without the use of boundary layer
pitch type and should be capable of responding to the control (BLC) on the sphere.
cyclic variation in airspeed. Size will be larger than
normal for aircraft because of low blade speed. Stresses (FIGS. 3-8)
on propeller, gear box and turbine rotor due to gyro Aircraft 10B shown in FIGS. 3-6 is for example,
scopic moments will have to be considered. Effect of 30 designed to carry a 55 ton useful load. It includes a
cross winds due to horizontal speed must also be con central sphere 14B approximately 50 feet in diameter
sidered in propeller design if a serious problem should (the exact size depends on the actual weight of the final
develop. The engine and prop could be mounted with a design) and four equatorially mounted, externally sup
vertical and horizontal tail to hold the thrust line di ported wings 24B with turboprop engines 50B mounted
rectly into the relative wind. 35 thereon. The control console or cab 40B and load 12B
Due to location of the center of buoyancy above the (not shown) are suspended from the center of the
center of gravity, aircraft 10 will with collective lift sphere through a tapered or cone-shaped lower access
control only be capable of vertical ascent and descent indentation 300B.
and is statically stable in this mode. The static stability Control is for example, by cyclic and collective actu
will vary widely depending on the sling load since this 40ation of the rotating wings. Cyclic command permits an
load is conveniently slung from the south pole of the axial tilt of plus or minus 30 for 360 vectorable thrust.
sphere even without a sling load. However, the weight Wing configuration and power selection may provide
of the control cab, sling and fuel will keep the vehicle for example, support of 54 percent of the sling load
statically stable. Assuming for a 30,000 lbs. sling load plus a thrust component for vehicle translation. The
vehicle, the control cab sling and fuel wieght 5,000 lbs, 45 remaining 46 percent of payload support plus all struc
the unloaded static stability is 14% of the loaded stabil tural weight and fuel is carried by the aerostatic lift
ity. generated by the contained helium.
In order to achieve other than vertical flight, a cyclic Aircraft 10B involves the integration of a very large
lift control as previously discussed must be utilized to tip-driven helicopter rotor with an aerostatically buoy
overcome the static stability and cause the balloon and SO ant centerbody. Since the rotor is very lightly loaded
wing to tilt in the direction of desired horizontal mo (about 0.6 lb/sq. ft. of disc) and has low tip speed
tion. As the aircraft translates, differences in the lift (about 200 ft./sec.), centrifugal forces are not a signifi
distribution on the advancing and retreating wings will cant factor in the structural support of the rotor. The
in spite of equalized lift cause unequal moment about low rotor speed, however, allows the use of a braced
the balloon center with resultant lateral tilt. This must 55 wing structure without significant power penalty, and
be compensated for by some lateral as well as fore and the large spherical buoyant center section provides
aft cyclic lift control. space for a deep cabane section without aerodynamic
A standard helicopter type control stick controlling penalty providing struts to which brace wires can be
the tilt of the balloon rotor by cyclic lift control is extended to support the wings in both the axial and
provided along with a normal collective lift lever. En 60 equatorial direction,
gine power is automatically adjusted by centrifugal Except for torsional requirements for wing cyclic
force to maintain a constant (or if desired, adjustable) control, and resistance to the propeller and engine
rotor angular velocity. gyroscopic moments, the center section structure is
In order to provide the lift control moments to angu one of pin-ended compression and tension members
larly adjust the wings, an air system is utilized with 65 providing a polygonal girder framework 70B having
compressor bleed from the engines if available or sepa twelve triangular sections 72B on its sides and two
rate low pressure pumps on each engine if not. Flow square sections 74B on top. In addition to acting to
from each engine is piped to a central manifold and carry through the wing load, the center structure pro
 3,976,265
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vides focal points for the aerostatic buoyancy and the Control of aircraft 10B involve the need for a balance
slingload. of aerodynamic lift forces from the rotating wing sys
FIG. 3 shows a top view and FIG. 4 a side view of the tem as established by pilot command. In the final analy
structure. Struts or girders 94B and 96B respectively sis, the ideal control command would be a signal estab
have triangular and square cross sections. The struts lishing the desired quantity of aerodynamic force from
consist of tubes 80B spaced far enough apart to provide a given wing. This may be accomplished through a wing
column stability and sufficient interbracing to break angle of attack/force servo-system (later described ) or
the tubes into short enough sections to prevent local by means of a more direct system as disclosed herein as
column failures. Wing 24B consists of a box spar center the "lift command system'.
section 82B about 3% ft. square which resist column The rigid wings required and the lack of high centrif
bending, shear and torsion loads. ugal forces make the normal cyclic pitch control such
Power plants 50B are mounted on spar 82B at ap as used in helicopters impractical possibly because of
proximately 75% of the wingspan from the root 26B in the high load factors which would be required on the
a normal manner, except for the requirement to resist wings due to gust loads. Use of cyclic lift control could
centrifugal and gyroscopic forces. The service lines 5 reduce the required gust load factors and result in a
84B including fuel supply lines, hydraulic, pneumatic saving in structural weight. The control system pro
and electric lines, engine and propeller controls, and posed for aircraft 10 is therefore "Lift-Control' rather
instrumentation leads, pass through girder 96B wing to than pitch control of the conventional helicopter. Each
the root where they pass through flex joints 86B into wing is pivoted on a spanwise hinge ahead of the aero
the center section. 20 dynamic center of the symmetrical wing section. The
FIG. 4 shows the slingload and cab suspended near control system provides the torque to resist the ten
the sphere center. Universal joint 42B is provided at dency of the wing to trail at zero lift. The lift on each
the suspension point to allow the load-cab suspension blade will then be a linear function of this torque.
tube 18B angular freedom as the balloon and wings 25
rotate. All controls and instrumentation pass through = KT
or around this joint. The center section above this point Application of an equal torque to each blade (wing) is
contains the APU's for auxiliary power, and any gyro
stabilized reference which may be required for control. by collective lift control (corresponding to collective
The control cab 40B and load 12B (not shown) are pitch control for conventional helicopter).
attached to the lower end of suspension tube 18B. Cab 30 A symmetrical airfoil is preferred as the aerodynamic
40B is mounted on bearing 50B around the tube and its thrust of the rotating wing system must be both positive
azimuth is controlled by a tail rotor system 44B. A tail and negative (loaded and unloaded flight) and it is
rotor is used in preference to a direct retro-drive (such desirable to maintain a constant center of pressure of
as 54, 56 and 58 of FIG, 1A) to the support tube to the wing for required changes in angle of attack. In the
avoid the uneven angular motion of the universal joint 35 lift command system a symmetrical airfoil is used (but
from being transmitted to the cab. A retro-drive 54B, non-symmetrical airfoils can also be used) with the
56B and 58 provides a redundant cab antturn system, wings free to revolve about a hinge point 114B forward
since upon any tail rotor failure, the cab can be at of the aerodynamic center 115B as shown in FIG. 7. A
tached to the load anti-rotation system, (not shown). pitch horn 100B is attached to the wing so that a force
The operator's position must allow maximum visibil 40 applied to the pitch horn 100B would cause rotation of
ity downward and forward, and may allow for swivel the wing 24B about the hinge point center line 114B.
ling of the control position or a second operating posi With no force applied to the pitch horn, any airflow
tion with a view of the load. The cab can also be over the wing would not generate a moment (neglect
equipped with a hoist system 88B for access from the 45 ing wing weight) and the wing would be in a trailing
ground and an egress on the top with a hoist system to position. In the lift command system a force is applied
allow personnel to enter the center section of the to the pitch horn proportionate to the amount of lift
sphere, and access from there to all other areas requir required from the wing. The wing angle of attack is
ing maintenance. The control cab may also have a determined from this force requirement rather than the
head, galley and bunks for off-duty crew and ferry SO normal method of control that selects an angle of at
missions. tack and accepts the force thereby generated.
Stability is the basic reason for attachment of the In the illustrated form of the invention, an air cylin
load to the center of aircraft 10B rather than at the der 102B contains a piston with rod 101B connected to
edge. Computer analysis indicates that there is essen pitch horn 100B. lf a positive thrust is required from
tially no oscillating motion for center attachment while 55 each wing 24B, then air is supplied through port 103B.
a period between 10 to 13 seconds could occur for The actual pressure experienced by the piston and
edge attachment of the load. Assuming a 50 ton slin transmitted through the rod 101B to pitch horn 100B is
gload aircraft with an advance ratio (i.e., the ratio of a function of the quantity of air allowed to flow through
wing rotational velocity to forward velocity of the air duct 104B.
craft) of 0.2, analysis indicates that the period of in FIG. 8 schematically illustrates the swash plate con
duced oscilation due to vehicle dynamics would be 2.4 60 trol assembly that is physically in the cab 40B of air
seconds if the slingload were attached at the edge while craft 10B. Swash plate 105B (actuated by control input
the period would be 137.9 seconds if the load were 122B) maintains a fixed orientation to control cab 40B
attached at the center. While a 2.41 second time while linkage 107B, 108B, and port valves 109B and
(11.38 second period) is well within the response time 65 1 10B are free to rotate on extension cylinder 120B with
of the pilot, center attachment does offer levels of basic the sphere wing assembly 24B by reason of isolation
stability unheard of in any rotor system previously bearing assembly 111 B. Four valves 109B and 110B
known, reflecting the result of a common center of (two for each wing) are provided at 90° intervals
buoyant lift, rotor thrust vector and load attachment. around cylinder 120B.
 3,976,265
9 10
In the position shown in FIGS. 7 and 8, valve 109B is Examination of altitude pressure differentials discloses
controlling the flow of air from duct 103B. Duct 104B that envelope elongation will be in the neighborhood of
is the bleed air duct that controls the force of the in one percent per l,000 feet of altitude change. Careful
coming air from port 103B that is being applied to the selection of envelope material will permit this amount
rod 101B. Complete blockage of duct 103B by valve of elongation to be accepted within the design specifi
109B applies the full force of the air entering port 103B cations of the material.
to rod 101B and thus commands a maximum aerody This system is in sharp contrast to other thermally
namic lift from wing 24B. If swash plate motion moved controlled systems in that the heating of the gas to a
valve 109B completely away from the opening of duct constant temperature precludes a volume change (due
103B, no pressure exists in cylinder 102B and the wing 10 to external temperature variations) and, therefore,
is in the trail position. does not basically affect the buoyancy of the system.
Application of air to port 112B changes the action of The advantages of this approach include the elimina
the system to permit valve 110B to act on the port of tion of the weight and cost of the balloonet system as
duct 104B, an extension of tube 104B, for control of well as the ability to modulate the temperature for
the vehicle in unloaded flight. Under these conditions, 5 programmed changes in altitude as might be required
the air supply is shut off port 103B and instead applied in long-range transport of the vehicle.
to port 1 12B of cylinder 102B. Thus a downward force During periods of inactivity when the engines would
is applied to rod 101B through the action of swash plate not be operating, the tiedown area could include he
105B through valve 1 10B. lium storage to maintain pressure in the envelope as the
Movements of valves 109B are 180 degrees out of temperature drops due to lack of continued heat from
phase for similar movements of swash plate 105B, i.e., the engines. Thus the craft would retain structural in
a downward movement of swash plate 105B tends to tegrity while moored to resist wind loadings.
close ports 104B, and while the same downward move The method of collecting waste heat from a gas tur
ment of swash plate 105B opens ports 103B. This re bine engine is shown in FIG. 6. The engine 50B is fitted
versal is exactly the desired condition to permit pilot 25 with a tube around which is coiled a fluid filled tube
commands to provide similar vehicle movements in assembly 201B. Engine exhaust heats the fluid and this
loaded or unloaded flight. fluid is circulated through pipes 200B and 202B under
In the operation of the system, cyclic or collective the influence of temperature control 206B. At the cen
commands establish a desired force for each wing. If ter of the vehicle, a heat exchange system consisting of
the wing experiences a gust, the changed aerodynami 30 a radiator 203B and fan 204B transfer the heat of the
cally generated force compels the wing to seek a differ fluid to the helium.
ent angle of attack to keep the new force in balance Boundary layer control can be used to overcome the
with the command force exerted by rod 101B through Magnus effect and thereby reduce the drag of the
the pitch horn 100B. Thus, gust alleviation is a built-in sphere. One method would be to provide for injection
feature of the system. While the pneumatic system 35 of air into the boundary layer on the advancing hemi
shown is deemed desirable, the same effect can be sphere. This could be accomplished by sequentially
achieved with suitable electrical or hydraulic systems. supplying air at adequate volume and pressure to ports
Another basic approach to a command thrust control located on the skin of the sphere with provisions for
system is to: (1) sense the thrust of each wing as a force deflecting this air into the boundary layer counter to
being applied through the wing support points, (2) 40 the circulation induced by sphere rotation. The result
compare this force to the computed force required would be to accelerate the air on the advancing side of
based on the control command at that time, and (3) the sphere to a velocity comparable to the air on the
activate a servo loop to change the angle of attack of retreating side of the sphere.
the vane to provide the required force. Forces devel A drag reduction envelope can eliminate any possible
oped by gusts would be quickly balanced to the desired 45 drag due to Magnus forces. An external shield can be
level by the servo loop angle of attack command. This attached in the form of two hemispheres of fabric at
"fly-by-wire" control system is well within the state of tached to the main sphere near the equator by means of
the art and reduces the need for system coordination by a roller bearing system or a "zipper' technique that will
the pilot. Signals from automatic ground station posi allow a relative rotation between the spherefwing as
tioning equipment could be easily accepted by this SO sembly and the external shield. The external shield
class of control system. would be driven so as to present a non-rotating surface
The normal method of compensating for pressure to the air stream.
variations in aerostatically buoyant vehicles is through While the spherical centerbody has the advantage of
the use of a ballonet system wherein a small flexible simplicity, there are alternate configurations that offer
container of air is maintained within the main envelope 55 performance improvements. If the centerbody is flat
containing the buoyant gas. As the vehicle changes tened at the poles into an oblate spheroid and a propul
altitude or experiences temperature variations, the sion system provided (such as aux. engines mounted on
change in pressure of the buoyant gas is allowed to top and/or bottom, or cycloidal propulsion vanes on
modulate the volume of the balloonet by forcing air out the wings such as shown in U.S. Pat. No. 3,166,129)
of the ballonet or requiring the insertion of air. 60 that did not demand equatorial tilt to supply a horizon
In aircraft 10B, the engines producing considerable tal thrust vector component, then the overall drag of
quantities of heat are used to maintain a constant tem the system would be substantially reduced permitting
perature of the buoyant gas by means of temperature higher speeds and/or increased efficiency.
control 206B. As a constant temperature is maintained For long range missions where the payload (oil, grain
above the maximum expected temperature that would 65 etc.) could be carried at the center of gravity of the
be produced by external environmental forces, e.g., sphere, a cone-shaped inflatable section could be
Solar heating or atmospheric heating, the pressure of added onto the lower hemisphere and the axis of the
the gas remains constant except for altitude variations. vehicle at or near neutral buoyancy could be horizontal
 3,976,265
1 12
with the rotating wing system acting as a propeller. In system being constructed and arranged to predeter
this mode, collective wing control would establish over mine an aerodynamic force and then to adjust the ef
all propulsion efficiency and speed while cyclic wing fective angle of attack of said wings to obtain and main
control would provide directional control. tain said predetermined aerodynamic force.
I claim: 3. A composite aircraft as set forth in claim 2 wherein
1. A composite aircraft comprising a large balloon said lift command control system comprises a pneu
chamber containing a lighter-than-air gas which pro matic system.
vides a large static lifting force having a magnitude 4. A composite aircraft comprising a large balloon
substantially greater than the weight of said aircraft, chamber containing a lighter-than-air gas which pro
said aircraft having a substantially vertical axis, a set of O vides a large static lifting force having a magnitude
substantially horizontally disposed wings extending substantially greater than the weight of said aircraft,
radially relative to said vertical axis, a structural assem said aircraft having a substantially vertical axis, a set of
bly connected to said aircraft at said vertical axis for substantially horizontally disposed wings extending
supporting said wings in a substantially horizontal ra radially relative to said vertical axis, a structural assem
dial array relative to said aircraft, rotatable coupling 15 bly connected to said aircraft at said vertical axis for
means connecting said wings to said structural assem supporting said wings in a substantially horizontal ra
bly and permitting adjustment of the effective angle of dial array relative to said aircraft, rotatable coupling
attack of said wings, thrust means mounted upon said means connecting said wings to said structural assem
wings whereby said wings and chamber are rotated bly and permitting adjustment of the effective angle of
about said axis, control means connected to said wings 20 attack of said wings, thrust means mounted upon said
for varying their effective angle of attack to either wings whereby said wings and chamber are rotated
provide a dynamic lifting force for augmenting said about said axis, control means connected to said wings
static lifting force whereby said combined static and for varying their effective angle of attack to either
dynamic lifting forces are sufficient to lift large weights provide a dynamic lifting force for augmenting said
or to provide a strong negative dynamic lift for over 25 static lifting force whereby said combined static and
coming said static lift and moving said aircraft towards dynamic lifting forces are sufficient to lift large weights
the ground, said control means comprising a lift com or to provide a strong negative dynamic lift for over
mand control system, said lift command control system coming said static lift and moving said aircraft towards
being constructed and arranged to adjust the effective the ground, said control means comprising a lift com
angle of attack of said wings to obtain a predetermined 30 mand control system, and said lift command control
aerodynamic force, said structural assembly compris system being constructed and arranged to adjust the
ing a girder network emanating substantially from the effective angle of attack of said wings to obtain a prede
center of said balloon chamber, an indentation in the termined aerodynamic force, said lift command control
bottom of said balloon chamber having its apex dis system comprises a pneumatic system, said pneumatic
posed substantially at the center of said balloon cham 35 system comprises cylinder and piston assemblies react
ber, a control console being disposed below said bal ing between said balloon chamber and said wing for
loon chamber, rotatable joint means connecting said adjusting their effective angle of attack, air bleed valves
control console substantially to the center of said girder connected to said cylinder, a swash plate input control
network, a stabilizing device being connected to said in said lift command control system, and a connecting
control console for preventing it from rotating with said 40 linkage between said swash input control and said
balloon chamber, heating means in said balloon cham bleed valves for adjusting said angle of attack.
ber for controlling the temperature and lifting force of 5. A composite aircraft as set forth in claim 4 wherein
said lighter-than-air gas in said chamber and tempera said air bleed valves are mounted on a ported cylinder
ture control means connected to said heating means for 45 connected to rotate with said balloon chamber.
controlling the internal pressure of said aircraft. 6. A composite aircraft as set forth in claim 5 wherein
2. A composite aircraft comprising a large balloon said air bleed valves are rotatably isolated from said
chamber containing a lighter-than-air gas which pro swash plate by a circular bearing,
vides a large static lifting force having a magnitude 7. A composite aircraft comprising a large balloon
substantially greater than the weight of said aircraft, 50 chamber containing a lighter-than-air gas which pro
said aircraft having a substantially vertical axis, a set of vides a large static lifting force having a magnitude
substantially horizontally disposed wings extending substantially greater than the weight of said aircraft,
radially relative to said vertical axis, a structural assem said aircraft having a substantially vertical axis, a set of
bly connected to said aircraft at said vertical axis for substantially horizontally disposed wings extending
supporting said wings in a substantially horizontal ra 55 radially relative to said vertical axis, a structural assem
dial array relative to said aircraft, rotatable coupling bly connected to said aircraft at said vertical axis for
means connecting said wings to said structural assem supporting said wings in a substantially horizontal ra
bly and permitting adjustment of the effective angle of dial array relative to said aircraft, rotatable coupling
attack of said wings, thrust means mounted upon said means connecting said wings to said structural assem
wings whereby said wings and chamber are rotated bly and permitting adjustment of the effective angle of
about said axis, control means connected to said wings 60 attack of said wings, thrust means mounted upon said
for varying their effective angle of attack to either wings whereby said wings and chamber are rotated
provide a dynamic lifting force for augmenting said about said axis, control means connected to said wings
static lifting force whereby said combined static and for varying their effective angle of attack to either
dynamic lifting forces are sufficient to lift large weight provide a dynamic lifting force for augmenting said
or to provide a strong negative dynamic lift for over 65 static lifting force whereby said combined static and
coming said static lift and moving said aircraft towards dynamic lifting forces are sufficient to lift large weights
the ground, said control means comprising a lift com or to provide a strong negative dynamic lift for over
mand control system, and said lift command control coming said static lift and moving said aircraft towards
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13 14
the ground, said structural assembly comprising a and a stabilizing device being connected to said control
girder network emanating substantially from the center console for preventing it from rotating with said bal
of said balloon chamber, an indentation in the hottom
of said balloon chamber having its apex disposed sub loon chamber.
8. A composite aircraft as set forth in claim 7 wherein
stantially at the center of said balloon chamber, a con 5
trol console being disposed below said balloon cham said girder network comprises a substantially polygonal
ber, rotatable joint means connecting said control con network.
Sole substantially to the center of said girder network,
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