The present invention relates to a system for controlling the lift
of an aircraft. More particularly it relates to a system for a controlling lift
in an airship or balloon using a lighter-than air gas.
Airships have the potential to carry large quantities of goods, or
passengers. This potential is best realized in a rigid-body airship, as opposed
to the flexible body airship or blimp, because of the structural demands placed
on the materials used.
Airships have a problem in landing and load-carrying due to having
a fixed displacement of air by lighter than air gas. Due to the usage of fuel during
a flight the airship gets lighter and because it has a fixed displacement the airship
has to be powered down to earth by the use of the engines. It then involves many
ground crew to stabilize and secure it. Similarly, for balloons (for example hot-air
balloons and Helium balloons) variables, such as air temperature, make the landing
very difficult to control.
It is an object of the present invention to provide a system that
alleviates these problems. A further object is to provide a controlled take off,
flight, and landing for airships from ground level or other base without disposing
of ballast. This would give airships the ability to load and unload whilst on the
ground or base station. Yet another object is to provide a compressor for use in
such a system.
According to a first aspect of the present invention there is provided
a system for controlling lift of an aircraft, comprising: an inflatable compartment
for containing a gas which is lighter than air; a receiver for receiving and storing
the gas in a compressed condition; and means for compressing the gas and transferring
it from the inflatable compartment into the receiver thus reducing the lift force
on the aircraft.
The system preferably further comprises means for expanding the gas
and transferring it from the receiver into the inflatable compartment thus increasing
the lift. A valve means may be provided for controlling the transfer of the gas
between the receiver and the inflatable compartment. Preferably, the receiver is
directly coupled to the inflatable compartment via the valve means and the means
for compressing the gas, thereby providing a closed system.
In one embodiment, the aircraft is a balloon. The receiver may be
a fixed dimension receptacle. Alternatively, the receiver may be an inflatable receptacle,
the inflatable compartment being manufactured from a material that is more easily
inflatable than the receiver.
In another embodiment, the aircraft is a rigid-body airship. The airship
may comprise a metal shell, preferably of Aluminium. A variable displacement compartment,
containing air, may surround the inflatable compartment. An opening may be provided
in the rigid aircraft for air to pass into and out of the variable displacement
compartment when the inflatable compartment is inflated and deflated.
The system may employ a plurality of inflatable compartments and variable
displacement compartments, each inflatable compartment being housed within a respective
variable displacement compartment.
The system may further comprise a fixed displacement compartment containing
a gas, which is lighter than air. This compartment provides a fixed lift to overcome
the dead weight of the airship, with the variable displacement compartments being
used to vary the lift.
The gas is preferably an inert gas, more preferably Helium.
The system of the invention is one in which the amount of lift is
controlled by varying the amount of Air displaced by Helium (or other lighter than
air gas). This is made possible by, but not exclusively, the use of at least part
of the airship having compartments that have fixed displacement and others that
have variable displacements.
According to a second aspect of the present invention there is provided
an aircraft lift control diaphragm compressor, comprising: first and second chambers
having a common wall that comprises a diaphragm; means for compressing a first gas
in said first chamber so as to displace said diaphragm towards said second chamber
and compress a second, lighter than air, gas therein; and valve means for controlling
charging of said second chamber with said second gas and discharging of said compressed
second gas from said second chamber.
Due to the size of the helium molecule being far smaller than the
constituents of air, it is difficult to compress with standard piston compressors
and so this aspect of the invention concerns the application of the diaphragm pump
or compressor for use in airships and balloons. The diaphragm pump or compressor
has the advantage that the unit is hermetically sealed from the outside environment
and therefore cannot let contaminants in or the helium out to atmosphere once fitted
into a closed loop system.
The means for compressing the first gas in the first chamber may comprise
a positive displacement compressor, which may be a piston having a reciprocating
motion, whereby the first gas in the first chamber is decompressed by a return stroke
of said piston, such that the second chamber is charged and discharged as a result
of movement of said diaphragm towards and away from said second chamber during alternating
strokes of said piston in opposing directions.
In a preferred embodiment, the diaphragm is constructed of metal.
This is advantageous because Helium will not permeate through the metal as it would
through, say, a polymer material.
According to a third aspect of the present invention there is provided
a rigid body airship comprising: a shell for containing a lighter than air gas;
at least one variable displacement compartment within said shell, the variable displacement
compartment having an associated inflatable container therein; a receiver for receiving
and storing said gas in a compressed condition; means for compressing the gas and
transferring it from the inflatable container into the receiver so as to reduce
the lift force on the aircraft; means for expanding the gas and transferring it
from the receiver into the inflatable container so as to increase the lift; and
at least one opening in said shell for allowing air to pass into and out of the
variable displacement compartment.
Embodiments of the present invention will now be described with reference
to the accompanying drawings, in which:
- Figures 1 and 2 show two conditions of a helium balloon;
- Figure 3 is a sectional elevation of an airship; and
- Figure 4 is a sectional elevation of a diaphragm pump.
Referring to Figures 1 and 2, a Helium balloon has an outer balloon
envelope 1 and an inflatable receiver 2. A valve station 3 and a compressor 4 are
suspended underneath the balloon envelope 1. By the use of the compressor 4, the
lift gas can be transferred from the balloon envelope 1 into the receiver 2. The
receiver 2 could be an inflatable inner balloon (as shown in Figures 1 and 2) that
requires pressure to inflate, or a fixed dimension receptacle (not shown).
One arrangement is to have the outer balloon envelope 1 manufactured
from a suitable material that needs very little pressure to inflate it, with the
receiver 2 as a second balloon either inside or outside the balloon envelope 1,
but for this illustration will be described as inside. The receiver balloon 2 would
be smaller and manufactured from a material that would stretch upon inflation and
would require pressure to inflate it so as to reduce the volume of the inflating
gas. The receiver balloon 2 would be directly coupled to the outer balloon 1 via
the valve station 3 and compressor 4 so as to complete a closed loop system.
For pressure regulation, for example in response to the heating of
the outer balloon 1 contents by the sun or air temperature, this can be controlled
by the transfer of the lift gas from the outer envelope 1 to the inner balloon 2
or vice versa by the compressor 4 and valves 3.
The compressor 4 could be driven directly, either by an engine, or
an electric motor powered from an engine driven electric generator or battery or
both The control of the transfer of the lift gas could be manual or by programmable
controller via a key-pad or other system.
The condition of the balloon shown in Figure 1 provides a reduced
lift. Part of the lift gas has been transferred from the balloon envelope 1 into
the receiver 2 and is held under pressure reducing the displaced volume of the balloon
envelope 1. The condition shown in Figure 2 provides maximum lift. The lift gas
has been transferred from the receiver 2 into the balloon envelope 1. On transfer
the compression is removed and the gas expands to give the balloon envelope 1 a
much larger displacement and therefore more lift.
By control of the amount of transfer the lift may be varied to suit
the requirements of the operator. This principle of the invention could be used
as a single unit in a balloon (as shown in Figures 1 and 2) or as multiple units
in compartments of a multi compartment air ship (as will be described in more detail
Referring to Figure 3, a rigid body airship 10, has a metal body shell
12 formed of aluminium or lightweight alloy. A load-bearing hold 14 is suspended
underneath the body shell 12.
C1, C2, C3 are fixed displacement compartments containing a lighter-than-air
gas such as Helium, giving a combined lift just under the total weight of the airship
10. R1, R2, R3, R4 are rear variable displacement compartments. Inside each of the
variable displacement compartments R1, R2, R3 and R4 is an inflatable. R1X, R2X,
R3X, R4X are rear receivers with associated compressors. F1, F2, F3, F4 are front
variable displacement compartments, each with an inflatables, and F1X, F2X, F3X,
F4X are the receivers with associated compressors.
Each of the variable displacement compartments R1, R2, R3, R4, F1,
F2, F3, F4 is provided with a vent opening (not shown) through the shell 12 to allow
air displaced from compartment to escape to the surroundings when the inflatable
is inflated, and to allow air from the surroundings to enter the compartment when
the inflatable is deflated. The vent openings are preferably sited on the underside
of the shell 12 because any Helium escaping from an inflatable, being lighter than
air, will rise towards the top of the compartment.
The fixed displacements C1 and C3 are provided to give sufficient
lift to support the structure at each end of the airship 10 to prevent cantilever
loads to the structure when the lift in the variable compartment is reduced or removed.
Helium gives a lift of 1 kilogram per cubic metre. Therefore, by mathematical
calculation of the volume of compartments C1, C2, C3 with regard to the overall
weight of the airship, a suitable ship can be constructed. Compartments F1, F2,
F3, F4 and R1, R2, R3, R4 give final lift to include passengers and cargo.
In the arrangement shown in Figure 3, the fixed compartments C1, C2,
C3 would have a lift force of an amount slightly lower than the weight of the airship
10, thus keeping the airship 10 firmly on the ground when being loaded or out of
use. The variable compartments F1, F2, F3, F4, R1, R2, R3, R4 would have compressed
Helium (or other inert lighter than air gas) stored in the receivers F1X, F2X, F3X,
F4X, R1X, R2X, R3X, R4X. Each variable compartment F1, F2, F3, F4, R1, R2, R3, R4
has an inflatable fitted inside. Through the use of suitable valves the Helium (or
other lighter than air gas) would, in a controlled way, be transferred from a receiver
(for example R1X) to the associated inflatable. As inflation takes place this would
displace the air in that variable displacement compartment (R1) and add to the lifting
force. By controlling which variable compartment was inflated or the amount of the
inflation taking place then the airship would rise in the air to a height required
by the controller.
Selecting the forward F1, F2, F3, F4 or rear R1, R2, R3, R4 variable
compartments for inflating would set the pitch of the airship 10, as required. Adjustment
of the amount of inflation of selected compartments may be used to set the trim
for the airship 10 in flight. The trim could also be maintained by transfer of Helium
(or other inert lighter than air gas) from one variable compartment to another by
way of the compressors and valves.
In order to land the airship 10, the Helium in the variable compartments
F1, F2, F3, F4, R1, R2, R3, R4 would be re-compressed into the receivers F1X, F2X,
F3X, F4X, R1X, R2X, R3X, R4X by the compressors, deflating the inflatables and reducing
the displacement of the air, thereby reducing lift. By carefully controlling the
flow of Helium (or other inert lighter than air gas) from inflatables to receivers
F1X, F2X, F3X, F4X, R1X, R2X, R3X, R4X a smooth descent to the landing area would
In this way the Helium (or other inert lighter than air) gas is reused
and is encapsulated in a closed loop system.
The stored Helium (or other lighter than air gas) in the receivers
F1X, F2X, F3X, F4X, R1X, R2X, R3X, R4X could also be used to top up the fixed displacement
compartments C1, C2, C3 as and if required.
It should be noted that in flight most of the compressed receivers
would be at a very low or zero pressure.
It is within the scope of the invention to have all compartments with
variable displacement, but this would depend on the practicalities of construction.
Figure 3 shows one arrangement of both fixed and variable compartments
but these could be changed by position or quantity to suit particular design requirements.
The transfer valves and compressors could be controlled by hand or
an onboard Computer or Programmable Logic Controller or by other devices.
In order for the system described above to operate effectively, a
suitable compressor is required to compress the lighter-than-air gas from the variable
displacement compartment into the receiver. Because the helium molecule is far smaller
than that of the constituents of air, it is difficult to compress with standard
piston compressors and so this aspect of the invention concerns the application
of the diaphragm pump or compressor for use in airships and balloons. The diaphragm
pump or compressor has the advantage that the unit is hermetically sealed from the
outside environment and therefore cannot let contaminants in or the helium out to
atmosphere once fitted into a closed loop system.
One such diaphragm unit will now be described as an add-on module
to a standard piston compressor. With reference to Figure 4, a module A is fitted
in place of the cylinder head on a piston compressor 20, having a cylinder B inside
which a piston C reciprocates. A diaphragm D forms part of a wall separating a chamber
F in the module A, from the cylinder B. When the piston C moves up, the air in the
cylinder B compresses and deflects the diaphragm D, causing the helium in the chamber
F to be compressed. The helium is then forced through a non-return valve E. On the
down stroke of the piston C, the air compression is removed and the diaphragm D
returns to its normal position so that helium is forced into the chamber F through
another non-return valve G by the outside pressure. It will be appreciated that
this return stroke may set up a negative pressure in the chamber F so as to suck
helium in through the non-return valve G.
The diaphragm D itself is preferably formed of a thin metal. This
is preferable to other flexible materials, such as polymers, because metals are
much less permeable to helium.
It is within the scope of the application that the diaphragm pump
or compressor can be operated by any of various means such as hydraulics or pneumatics
by hand lever or electric motor or engine driven units.