AeroLift CycloCrane
Encyclopedia
The AeroLift CycloCrane was a unique US hybrid airship
which adopted helicopter
derived airfoil control for low speed flight manoeuvring by spinning on its axis. It was intended to be a heavy load lifter, initially aimed at the Canadian logging industry. A proof of concept vehicle flew at times during the 1980s, but no large production aircraft were built.
with a novel drive and control system not based on the usual method involving numerous external, tiltable engines. The Aerolift CycloCrane was a most unusual aircraft, probably unique in combined a lighter than air
main lift source, or aerostat
, with helicopter
and fixed wing methods to provide three dimensional drive and attitude control.
Two proof of concept versions were built, different in size and detail but using the same layout. Each had a conventional, streamlined semi-rigid
helium gas bag or aerostat to provide most of the lift need to support the aircraft and its load. The aerostat contained a rigid internal axle along its long axis, upon which it could rotate. Half way along the axle, two long beams were fixed at right angle to it and to each other, passing through the envelope where they carried four narrow wings of symmetric airfoil
section, or blades as AeroLift termed them. Each blade carried at its tip another, shorter, wing mounted with its long axis perpendicular to the plane of the blade, making a shallow T shape. The blades could be rotated and in normal forward flight their surfaces were nearly parallel to the aerostat's longitudinal axis, both blades and wings providing lift in the conventional way. This lift balanced the difference between gross weight and buoyancy, typically about half the load weight. At the end of the blades, above the wing, were pylons that carried propeller driving engines, oriented at right angles to both wing and blade long axes, so they powered the aircraft forward in normal flight.
At low speeds, for example when manoeuvring to pick up a load, these T shaped aerofoils were rotated though about 90° so the blades were perpendicular to the normal flight direction and the engines pointed around the circumference. They caused the aerostat and its aerofoils to rotate about its axis, clockwise as seen from the rear. In this condition, at rotational speeds of about 13 rpm, changes in the angles of attack
(pitch
) of the blades and of the wings could provide changes of orientation and velocity. Collective changes of the pitch of the blades moved the aircraft forwards or back; cyclic changes controlled both pitch and yaw. Cyclic changes of the angles of attack of the wings moved the aircraft up and down and from side to side. This wing motion also provided lift to balance any difference in weight and buoyancy when the CycloCrane was not in the forward flight mode.
Extensions of the central axle, forward and aft, provided anchorage points for cables supporting the pilot's cabin and any load connected to it. These cables had to clear the rotating blades and wings, setting the overall length and the depth of the cabin below the axle. The front axle extension also carried a control equipment housing and the longer extension at the rear carried a stabilising tail.
The first version of the CycloCrane was 138 ft (42 m) long, had four piston engines and was fitted with a large, inverted Y shaped tail, chiefly to stabilise it at its moorings by keeping it pointed into wind. It was completed in 1982 but was destroyed that year at its moorings in a storm. It was rebuilt by 1984, a longer aircraft at 178 ft (54.25 m) overall and fitted with an almost circular, 18 faceted, ring shaped tail wire braced to the central axis. Its aerostat was 68 ft 0 in (20.73 m) in diameter and 136 ft 0 in (41.45 m) long. Partly to save weight, this version had only two engines, a pair of 150 hp (112 kW) Textron Lycoming AEIO-320
horizontally opposed piston engines driving 4-bladed propellers. This left the CycloCrane rather underpowered, particularly in lift.
The revised CycloCrane began unmanned flights in August 1984 and made its first manned flight on 23 October 1984. By mid 1985 it had accumulated 7 hrs of flight under a US Forest Service contract, but the lack of power limited the spin rate to 10 rpm, rather than the designed 13 rpm so that the aircraft was less nimble in its movements than intended and also only able to lift loads of about half of the target 2 tons. AeroLift received several military contracts in the late 1980s to keep the CycoCrane idea afloat, particularly one from DARPA in 1988 for mooring investigations on a 36 ft model and renewal of the proof of concept aircraft for military suitability tests. For its final flights the tail was altered again into a combination of the early inverted Y within the ring of the first rebuild.
When the defence funding ended in 1990, the company ceased to trade.
Airship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...
which adopted helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
derived airfoil control for low speed flight manoeuvring by spinning on its axis. It was intended to be a heavy load lifter, initially aimed at the Canadian logging industry. A proof of concept vehicle flew at times during the 1980s, but no large production aircraft were built.
Design and development
AeroLift Inc was set up in 1980 by CycloCrane inventor Arthur Crimmins, with funding from five major Canadian logging companies, with the objective of building an aircraft capable of the heavy lifting of felled timber from remote sites. Their proposal was to use an airshipAirship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...
with a novel drive and control system not based on the usual method involving numerous external, tiltable engines. The Aerolift CycloCrane was a most unusual aircraft, probably unique in combined a lighter than air
Lighter than air
Lighter than air refers to gases that are buoyant in air because they have densities lower than that of air .Some of these gases are used as lifting gases in lighter-than-air aircraft, which include free balloons, moored balloons, and airships, to make the whole craft, on average, lighter than air...
main lift source, or aerostat
Aerostat
An aerostat is a craft that remains aloft primarily through the use of buoyant lighter than air gases, which impart lift to a vehicle with nearly the same overall density as air. Aerostats include free balloons, airships, and moored balloons...
, with helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
and fixed wing methods to provide three dimensional drive and attitude control.
Two proof of concept versions were built, different in size and detail but using the same layout. Each had a conventional, streamlined semi-rigid
Semi-rigid airship
Semi-rigid airships are airships with a partial framework. These often consist of a rigid, or occasionally, flexible, keel frame along the long axis under the aerodynamic hull envelope. The partial framework can also be located inside the hull...
helium gas bag or aerostat to provide most of the lift need to support the aircraft and its load. The aerostat contained a rigid internal axle along its long axis, upon which it could rotate. Half way along the axle, two long beams were fixed at right angle to it and to each other, passing through the envelope where they carried four narrow wings of symmetric airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....
section, or blades as AeroLift termed them. Each blade carried at its tip another, shorter, wing mounted with its long axis perpendicular to the plane of the blade, making a shallow T shape. The blades could be rotated and in normal forward flight their surfaces were nearly parallel to the aerostat's longitudinal axis, both blades and wings providing lift in the conventional way. This lift balanced the difference between gross weight and buoyancy, typically about half the load weight. At the end of the blades, above the wing, were pylons that carried propeller driving engines, oriented at right angles to both wing and blade long axes, so they powered the aircraft forward in normal flight.
At low speeds, for example when manoeuvring to pick up a load, these T shaped aerofoils were rotated though about 90° so the blades were perpendicular to the normal flight direction and the engines pointed around the circumference. They caused the aerostat and its aerofoils to rotate about its axis, clockwise as seen from the rear. In this condition, at rotational speeds of about 13 rpm, changes in the angles of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
(pitch
Blade pitch
Blade pitch or simply pitch refers to turning the angle of attack of the blades of a propeller or helicopter rotor into or out of the wind to control the production or absorption of power. Wind turbines use this to adjust the rotation speed and the generated power...
) of the blades and of the wings could provide changes of orientation and velocity. Collective changes of the pitch of the blades moved the aircraft forwards or back; cyclic changes controlled both pitch and yaw. Cyclic changes of the angles of attack of the wings moved the aircraft up and down and from side to side. This wing motion also provided lift to balance any difference in weight and buoyancy when the CycloCrane was not in the forward flight mode.
Extensions of the central axle, forward and aft, provided anchorage points for cables supporting the pilot's cabin and any load connected to it. These cables had to clear the rotating blades and wings, setting the overall length and the depth of the cabin below the axle. The front axle extension also carried a control equipment housing and the longer extension at the rear carried a stabilising tail.
The first version of the CycloCrane was 138 ft (42 m) long, had four piston engines and was fitted with a large, inverted Y shaped tail, chiefly to stabilise it at its moorings by keeping it pointed into wind. It was completed in 1982 but was destroyed that year at its moorings in a storm. It was rebuilt by 1984, a longer aircraft at 178 ft (54.25 m) overall and fitted with an almost circular, 18 faceted, ring shaped tail wire braced to the central axis. Its aerostat was 68 ft 0 in (20.73 m) in diameter and 136 ft 0 in (41.45 m) long. Partly to save weight, this version had only two engines, a pair of 150 hp (112 kW) Textron Lycoming AEIO-320
Lycoming O-320
The Lycoming O-320 is a large family of 92 different normally aspirated, air-cooled, four-cylinder, direct-drive engines commonly used on light aircraft such as the Cessna 172 and Piper Cherokee. Different variants are rated for 150 or 160 horsepower...
horizontally opposed piston engines driving 4-bladed propellers. This left the CycloCrane rather underpowered, particularly in lift.
The revised CycloCrane began unmanned flights in August 1984 and made its first manned flight on 23 October 1984. By mid 1985 it had accumulated 7 hrs of flight under a US Forest Service contract, but the lack of power limited the spin rate to 10 rpm, rather than the designed 13 rpm so that the aircraft was less nimble in its movements than intended and also only able to lift loads of about half of the target 2 tons. AeroLift received several military contracts in the late 1980s to keep the CycoCrane idea afloat, particularly one from DARPA in 1988 for mooring investigations on a 36 ft model and renewal of the proof of concept aircraft for military suitability tests. For its final flights the tail was altered again into a combination of the early inverted Y within the ring of the first rebuild.
When the defence funding ended in 1990, the company ceased to trade.