GB2440320A

GB2440320A - Amphibious gyroplane

Info

Publication number: GB2440320A
Application number: GB0614489A
Authority: GB
Inventors: Norman Frank Surplus
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-07-21
Filing date: 2006-07-21
Publication date: 2008-01-30
Also published as: GB0614489D0

Abstract

An amphibious gyroplane comprises a main fuselage (2, Fig 1) in the form of a floating hull and is supported and stabilised by separate, buoyant, outrigger sponsons (1a, 1b, Fig 1). The sponsons may have independently deployable wheels, which may be deployed conventionally for use on land and in various configurations to provide adjustable degrees of drag in water to aid maneuvering and providing counter torque on pre-flight rotation of the main rotor. The sponsons are characteristically positioned deeper than the main hull to enable the sponsons to support the partially lifted airframe just prior to take off. Provision may be made through the shape of the hull, sponsons and support spars (9a, 9b, Fig 1) to protect the aircraft propulsion system 5 from excessive spray. An emergency additional buoyancy system (11a, 11b, Fig 7) is also disclosed for involuntary rough water ditching, as well as an emergency secondary propulsion system.

Description

e: AMPHIBIOUS GYROPLANE -Background: Modern gyroplanes are designed to

land and take off from a hard, dry land, surface in common with most conventional fixed wing aircraft Unlike other types of aircraft however, the gyroplane has a comparatively steep glide path if it is unfortunate enough to suffer engine failure during flight. Whereas a fixed wing aircraft, flying at a precautionary high altitude, can hope to glide a reasonable distance in the event of a engine failure over water, the gyroplane cannot maintain altitude to the same extent whilst gliding to make the nearest suitable dry landing. This results in the gyroplane pilot being very averse to flying over even small stretches of open water such as estuaries and lakes. A gyroplane that has the capability to set down on (and take off from) non solid surfaces would greatly extend the versatility of this type of aircraft.

Conventional aircraft have been able to alight on water for almost as long as manned flight has been possible. The most common methods of enabling an aircraft to float on water has been to either use twin floats (as seen on float planes and helicopters) or a combination of a watertight fuselage (often given a hydrodynamic hull shape) and a set of remotely positioned (that is, not directly attached or adjacent to the main hull form) buoyant sponsons, typically fixed under the wings to give lateral stability at slow speeds on water (as seen on seaplanes and flying boats).

Fundamentally, seaplane wing sponsons are positioned to function at a lesser water depth than the main hull so that as speed is built up for take off, the aircraft rises onto "the step" (i.e. the main hull starts to plane on the surface of the water as opposed to ploughing through it) and the wing sponsons no longer make contact with the water. This reduces the wetted surface, thus reducing drag, allowing the aircraft to continue to accelerate towards eventual takeoff speed.

Therefore the last part of the aircraft to leave the water is the main hull of the aircraft.

To date attempts to produce a water borne gyroplane have proposed the use of floats which are added to the existing aircraft structure. This approach adds significant extra weight and drag to the existing structure. The present invention seeks to utilise the existing fuselage of the aircraft as a main source of the required buoyancy (as demonstrated by a conventional seaplane) combined with additional buoyant sponsons that are positioned remotely from the main hull form (to provide a very stable, wide based, buoyant tripod) This allows air to pass through the structure between the hull and the sponsons to reach the underside of the main rotor (a sufficient airflow to the underside of the main rotor is a pre-requisite for sustained auto-gyration) Further, the present invention uses the remotely positioned sponsons in an inverted configuration (when compared to a conventional seaplane) in that they are set deeper in the water than the main hull, to exploit the unique takeoff characteristics of the gyroplane. On land, a gyroplane is typically balanced on its main wheels prior to takeoff with much of the weight of the aircraft being taken by the main auto rotating rotor. As main rotor rpm increases so does lift and the aircraft simply rises into the air. On water, it is envisaged with the present invention, that when the aircraft is in its partially lifted state (i.e. in a "wheel balancing" stage on land) the main hull of the gyroplane is lifted clear of the water surface and the aircraft is balanced on its widely spaced sponsons only, until forward speed is built up to enable the main rotor rpm to increase sufficiently to allow the aircraft to rise fully into the air.

The driving propeller is protected from excess spray whilst the aircraft is in contact with the water in several ways. The main fuselage hull has a "beaver tail" extending out underneath the engine and driving propeller, which protects the propeller from below. Also, the side sponsons are positioned to minimise their spray action on the driving propeller during takeoff and fast taxiing.

Further, the sponsons have an angled underside surface and a predominantly vertical inboard edge that helps to deflect the water out to the sides rather than into the propeller area. (Rather like the deflection of snow by a skier whilst "snowploughing"). The struts supporting the sponsons can also be flared toward the front and rear of the fuselage to provide further splash protection for the propeller.

Statement of invention

AccordinQ to the present invention there is provided an amphibious pyroplane as claimed in claim 1.

To create a versatile, amphibious gyroplane, an embodiment of the present invention provide a conventional, home or factory built gyroplane airframe equipped with a hydrodynamic, buoyant main hull fuselage and separate, load supporting deep set sponsons. The sponsons are positioned in a tripod configuration relative to the main hull to provide maximum stability with minimum drag for a given quantity of buoyancy.

Having the sponsons remotely positioned from the main hull maintains a substantial airflow to reach the underside of the main rotor in order to promote and sustain lift by allowing the air to flow freely around and through the aircrafts main structure.

The sponsons are widely offset to each side of the main hull and also set back alongside and beyond the rear of the main hull to assist with both roll and pitch stability whilst on the water.

Further, as a significant amount of the sponsons length is set behind the aircrafts centre of gravity, the resultant additional drag of the sponsons helps with the yaw and pitch stability of the aircraft whilst it is in normal flight conditions (acting much like the drag inducing flight feathers of an arrow). The undersides of the sponsons are configured to deflect spray away from the main body of the aircraft whilst manoeuvring on the water. The supporting spars that connect the sponsons to the fuselage can be flared to provide stiffening for the structure and additional spray protection for the driving propeller. In some configurations the rear of the sponsons may be additionally attached to an alternative arrangement of aircraft tail surface. (This provides for a mutually supportive structure).

Further, the sponsons can support semi-or fully retractable wheels which, combined with a retractable nose wheel, enables the aircraft to become fully amphibious and, when asymmetrically deployed, can offer water/drag resistance to counter the rotational torque experienced by the aircraft during its pre-takeoff main rotor spin up.

The hydro-dynamically shaped fuselage has a boat hull profile (as commonly seen on conventional seaplanes) with the addition of a flat protrusion to the rear (shaped not unlike a beavers tail) which extends under the driving propeller to protect it from the spray and wash kicked up by the hull as the aircraft progresses through the water. This underside profile can be augmented by the use of flared sponson support spars, which gives further spray protection Further, additional, independently deployable, emergency buoyancy can be provided for extra stability in the event of forced ditching into rougher water. This can be fitted to both existing conventional land based gyroplanes (as an additional safety measure to prevent total aircraft loss when transiting open water) and the presently described amphibious version.

It is further envisaged that an emergency secondary form of propulsion can be provided to enable a gyroplane with engine failure to continue to sustain a level flight condition for a limited period in order to reach a more suitable and safer landing area when the need arises. This secondary propulsion may make use of existing parts of the primary propulsion system or, in other configurations, be totally self contained Again, this can be fitted to both conventional land based gyroplanes and the presently described amphibious version.

A further configuration is to combine a passively buoyant fuselage with twin inflatable sponsons that are usually stowed undeployed adjacent to the main wheels. In the event of making a forced water landing, the inflatable sponsons are activated allowing a normally land based gyroplane to alight onto the water and remain afloat. This system has the benefit of reduced drag during normal flight conditions whilst still retaining the benefit of supporting sponsons whilst on water.

Advantacies By enabling the Gyroplane to land and take off from both land and water during normal flight conditions, the aircraft will have a far greater potential area of operation. The aircraft will be able to transit large stretches of water, safe in the knowledge that should a forced landing occur, the aircraft will be able to set down on the surface of the water and remain there safely until assistance is received. Furthermore the pilot, at will, is able to deliberately make sheltered water landings and take offs, which vastly increases the potential landing sites available. Visiting a small rocky island, for example, could best be achieved by landing and taking off on the sheltered waters of a lee shore, bay or inlet, rather than actually landing on the dry land. Dispersed, offshore energy extraction facilities, such as wind, wave and tidal farms could be visited with far greater fuel efficiency compared to a helicopter of similar load carrying capacity.

Because gyroplanes use the rotational speed of the main rotor to generate lift, they don't need to rely on excessive ground speed to affect a takeoff. Whereas a light fixed wing aircraft may need to achieve 60-70 MPH to takeoff, a gyroplane typically leaves the ground at 20-30 MPH. This has a distinct advantage when considering a waterbome aircraft. The amphibious gyroplane needs only a relatively short stretch of sheltered water in which to affect a take off compared to a conventional seaplane or float plane. A further advantage is that the aircraft speed required while still on the surface of the water is greatly reduced.

A further advantage of using widely offset sponsons is to achieve greater roll stability (especially whilst on the water) whilst still maintaining a largely unimpeded path for the air to flow into the driving propeller and the underside of the main rotor (which is very necessary to maintain stable flight conditions). The use of a beaver tail and br a flared sponson support spars configuration on the rear of the main hull protects the driving propeller from excessive contact with the water whilst still allowing a good open airflow through the aircraft structure to feed the main rotor with its auto-rotational force.

Using sponsons that are also set back alongside and beyond the main hull helps increase pitch stability as well as raising and preventing the vulnerable drive propeller from striking the water.

The sponsons further protect the propeller area by acting as a physical barrier to prevent persons accidentally walking into the propeller. A further advantage is that in an alternative configuration the rear of the set back sponsons can be used to support (and gain mutual support from) a revised aircraft tail assembly.

Having individually deployable main wheels gives the advantage in water, that the wheels can be deployed asymmetrically to provide varying degrees of water drag. This is useful to provide a counteractive force to the turning force experienced during pre-rotation main rotor spin up (to maintain a steady course in the water rather than spinning around). Also the wheels can be deployed to generally slow progress or act as asymmetric water drags to aid low speed steerage.

Many functions currently undertaken by a helicopter of similar capacity could be camed out with greater inherent safety by an amphibious gyroplane. (If total engine failure occurs, the gyroplane main rotor is already inherently in a steady state of autorotation, whereas a helicopter pilot must immediately actively adjust the angle of attack of the rotor blades in order to successfully achieve an auto rotational state. During emergency engine off decent the gyroplane approaches the ground in a similar fashion to a normal landing, the helicopter has a lot more engine/gearbox weight to carry making the landing potentially more hazardous).

An amphibious gyroplane has the further advantage (over other types of amphibious fixed wing aircraft) of being able to alight on water outside a small harbour or marina, stop momentarily to align and secure the main 2 bladed rotor fore and aft, and continue to water taxi into the harbour to either tie up in a conventional manner alongside a pontoon or continue up a narrow slipway.

Typically fixed wing seaplanes and floatplanes, by virtue of their wide wings are restricted in their Advantaaes continued: close quarters manoeuvring capability, an amphibious gyroplane (with main rotor secured) has a long thin profile much more like a conventional yacht and as such would not be adverse to entering a busy marina or tying up in a high walled harbour. Further, with the main rotor secured, the aircraft presents a relatively low wind profile (as compared to, for example, a fixed wing floatplane) which helps with manoeuvnng in gusty conditions or whilst being taken under tow on the water.

The amphibious gyroplane is capable of safely flying to, and landing on, a comparatively short landing and takeoff floating platform or moored barge provide with a flight deck for the purpose (such as at a remote offshore energy installation).

When in waterborne configuration the amphibious gyroplane is well suited to land on numerous other surfaces as well as water (such as soft or compacted snow, thin ice, swampland, mudflats, rough boggy ground etc.) This is due again to the special characteristics of the gyroplane over conventional fixed wing aircraft. The slow landing speeds and little forward motion during set down means landing on such surfaces can be performed with great control and without any of the potentially hazardous downdraft unavoidably delivered by helicopters. This feature could be used to great effect as a temporary "first response" vehicle during search and rescue operations where a casualty has been located in a remote and/or inaccessible location. The aircraft could be set down near a casualty to provide initial assistance and communications for the subsequent coordinated rescue services. In extreme cases, this could be achieved regardless of whether the aircraft can affect an unaided take off from the area as the extraction of the aircraft would be a secondary consideration after the casualty's wetfare (in effect, the aircraft performs much like a life raft at this point) A gyroplane (conventional or amphibious) fitted with emergency buoyancy has the advantage of being able to confidently transit large, open/rough stretches of water, safe in the knowledge that in the unusual event that a ditching does occur, the aircraft can remain afloat on the surface of the water whilst awaiting assistance.

A gyroplane (conventional or amphibious) fitted with an emergency secondary propulsion system has the advantage of being able to confidently transit large, unsuitable landing areas (e.g. forests, marshland, open water, built up urban areas) safe in the knowledge that in the unusual event of an engine failure, effective flight can be maintained (for a limited period) by a secondary form of propulsion in order to reach a more suitable landing area.

Introduction to drawinas

An example of the invention will now be described by referring to the accompanying drawings -Figure 1 shows a plan view of the aircraft (minus overhead rotor assembly) -Figure 2 shows a stern (rear) profile of the aircraft (minus overhead rotor assembly and tail assembly) -Figure 3 shows a port (left) side profile of the aircraft in flight/water landing mode -Figure 4a shows a bow (head on) profile of the aircraft (minus overhead rotor assembly) -Figure 4b shows a different "head on' profile of the aircraft (again minus rotor assembly) -Figure 5 shows an underside view of the aircraft -Figure 6 shows a possible configuration for the deployable wheels -Figure 7 shows the deployment of emergency buoyancy where the bags are mounted to the main undercarriage -Figure 8 shows a different representation of how the main wheel assembly could be configured

Detailed description

In FIgure 1, a conventional gyroplane's main wheels have been replaced with side sponsons (Ia) & (1 b) and the aircraft fuselage has been adapted to form a watertight hull (2). These three points of contact with the water forms a very stable tripod base, giving sufficient buoyancy for the main areas of weight within the aircraft, namely the pilot/passenger space (3), airframe (4) and overhead rotor assembly (5) (4 & 5 both not visible in this view), the propulsion engine space (6) and tail assembly (7). The "beaver tail' hull form (10) used to protect the driving propeller (8) is also best seen on this plan view. Also shown are the supporting spars (9a) & (9b) that connect the sponsons to the fuselage. In this particular example the spars are visibly flared to provide stiffening for the structure and additional spray protection for the driving propeller.

FIgure 2 shows a rear view of the fuselage indicating the swept area of the driving propeller (8) but, for clarity, omitting to show the tail assembly. Here the predominantly flat underside "beaver tail' profile (10) can be viewed.

Figure 3 shows the port side of the aircraft in waterbome mode (and the dotted outline of a possible wheel down configuration).

When at rest in the water the weight of the craft is supported primarily by the main hull and side sponsons (the watertight tail assembly may or may not be partially immersed in the water depending on the trim and loading conditions place on the aircraft at any particular time). As the aircraft gets underway the engine (6) provides pre-flight rotation to the main rotor (5) (which is not drawn exactly to scale here but is merely an approximate representation). At the same time the propulsion propeller (8) is providing forward motion to the aircraft as it begins to taxi across the water. To oppose the counteractive torque experienced by the aircraft during the pre-rotation phase, one main wheel can be deployed in the "undercarriage down" position to provide rotational drag in the water to the forward thrust vector of the propulsion propeller. This turning force (assisted by the conventional air rudder in the tail fin) has the effect of opposing the counteractive torque of the pre-rotator allowing the aircraft to remain on a stow, stable forward heading through the water. Once pre-rotation of the main rotor is complete the pre-rotator is disengaged from the engine and the deployed wheel is retracted. At this stage the aircraft is moving slowly into the wind and the main rotor is starting to generate upward lift to the aircraft. As the main rotor speed increases due to the autorotation effect the aircraft becomes lighter still until such time that the main hull of the aircraft rises above the water surface. Crucially, the sponsons are arranged so that they are lower in the water than the main hull and so the much "lighter" aircraft proceeds balancing on the two outrigger sponsons alone. Further rotor RPM creates more and more lift until the aircraft simply lifts off the surface of the water.

Figure 4a shows a head on view of the aircraft. The boat hull shape of the main fuselage can be seen. The sponsons are set lower in the water than the main hull and have an underwater profile that encourages spray to be deflected away from each side of the aircraft.

Figure 4b shows a variation of figure 4a where the main hull is seen to display a much deeper V" profile. The sponsons however are still set lower in the water than the main fuselage.

Figure 5 shows an underside view of the aircraft. The pronounced bow section tapers towards the stern and flattens into the "beaver tail" section (10).

Figure 6 shows a gyroplane in an adaptation of the wheels down position for landing conventionally on hard surfaces. In this example the main wheels are accommodated within the middle sections of the sponsons (stowed undercarriage are described with dotted lines). If the aircraft is being launched into the water from, for example a siipway or beach, the wheels cariy the aircraft into the water until it is supported by its own buoyancy. Once afloat, the wheels can be retracted for taxiing out to the takeoff area. For pre-rotation of the main rotor, one main wheel can be deployed to provide a counter rotational force prior to the takeoff phase.

On landing the reverse procedure is used with the wheels being deployed prior to approaching the slipway or beach.

In the event of the aircraft suffering a forced ditching into rough water (i.e. in areas where sea state conditions are beyond normal landing conditions) the use of additional emergency buoyancy may be required (as marked (ha) & (lib) in Figure 7) Here, in this example, the emergency buoyancy system is provided in the form of inflatable bags complete with small compressed gas cylinders. Once activated from the cockpit the bags inflate to provide additional buoyancy and additional stability in the rough water. A small drogue, or sea anchor, may then be deployed from the aircraft's nose to keep it "head to sea" into the oncoming waves.

Figure 8 shows a further possible configuration of the main wheel assembly relative to a sponson. In this example, the stowed wheel rotates around a pivotal point or fulcrum (12) (an action which may also exist in other configurations) by means of a hydraulic, pneumatic, electrical or mechanical action employing levers, pulleys, wires or rope.

Claims

Claims 1. An amphibious gyroplane comprising a fuselage defining a hull

portion having a bow region, sponsons extending on either side of the fuselage, wherein the sponsons are arranged to extend below the lowermost region of the hull such that, when partially immersed, the sponsons are set deeper in the water than the hull portion.

2. An amphibious gyroplane as claimed in claim 1, wherein the sponsons are mounted on one or more outriggers extending outwardly and downwardly from the fuselage whereby each sponson is spaced from the fuselage.

3. An amphibious gyroplane as claimed in any preceding claim, wherein each sponson has an elongate keel portion.

4. An amphibious gyroplane as claimed in claim 3, wherein the keel portion of each sponson is angled towards a longitudinal axis of the fuselage in the normal direction of movement of the gyroplane.

5. An amphibious gyroplane as claimed in any preceding claim, wherein each sponson includes one or more selectively deployable wheels, each wheel being moveable between a retracted position, wherein the wheel is located within, or adjacent to, the sponson, and an extended position, wherein the wheel extends below the sponson to enable the gyroplane to land on and take off from a runway.

6. An amphibious gyroplane according to claim 5, wherein one or more of the wheels of at least one sponson may be independently deployed in order to provide symmetrical or asymmetrical drag forces while floating to aid general water borne manoeuvring and/or to counter a rotational moment caused by pre-flight rotation of the main rotor.

7 An amphibious gyroplane as claimed in any preceding claim, wherein the fuselage includes a rearwardly extending portion adapted to extend below a propulsion means of the gyroplane to shield said propulsion means from spray.

8. An amphibious gyroplane as claimed in any preceding claim, wherein the sponson supporting outrigger spars are flared to provide stiffening and to shield propulsion means from spray.

9. An amphibious gyroplane as claimed in any preceding claim, wherein the sponsons and the aircraft tail assembly provide mutual physical support.

10. A gyroplane which is fitted with additional, deployable buoyancy to aid floatation and stability in the event of an emergency ditching.

11. A gyroplane as claimed in claim 10 wherein the additional buoyancy comprises one or more inflatable chambers mounted on the body of the gyroplane.

12. A gyroplane which is fitted with an emergency secondary propulsion system, which when activated provides limited additional flight duration to allow safe transit to a more suitable landing site.

13 A gyroplane as claimed in claim 12 wherein the secondary propulsion system comprises a rocket motor.

14 A gyroplane as daimed in claim 12 wherein the secondary propulsion system utilises the existing primary fuel system.