ELECTRICAL VERTICAL TAKE-OFF AND LANDING AIRCRAFT

Abstract

Electrically powered Vertical Take-off and Landing (VTOL) aircraft are presented. Contemplated VTOL aircraft can include one or more electrical energy stores capable of delivering electrical power to one or more electric motors disposed within one or more propeller housings, where the motors can drive the propellers. The VTOL aircraft can also include one or more back-up and/or secondary energy/power sources (e.g., batteries, engines, generators, fuel-cells, semi-cells, etc.) capable of driving the motors should the energy stores fail or deplete. The VTOL aircraft will be significantly different to regular Tiltrotor aircraft as we use propellers and a modern steering system that reduces complicity dramatically. The contemplated configurations address safety, noise, and hover stability and outwash concerns to allow such designs to operate in built-up areas while retaining competitive performance relative to existing aircraft.

Claims

1. A winged electrically-powered vertical take-off and landing aircraft, comprising: a cockpit having a longitudinal axis; at least two wings, each wing extending each along an axis from the cockpit symmetrically with respect to said longitudinal axis of the cockpit; at least one electrical propeller unit arranged on each of the at least two wings, each of the at least one propeller unit comprising an electrical motor and a propeller linked to an arbor of the electrical motor so as to rotate about an axis of rotation; at least one of (a) each propeller and (b) at least part of the wings being tiltable in a vertical plane containing the propeller's axis of rotation with respect to the axis of the wing on which the propeller or the at least part of the wing is arranged; and each of said propeller unit being electrically connected to a primary electrical energy source disposed in said cockpit, wherein the aircraft further comprises an air-blowing steering system arranged at a tail of the aircraft to blow air in a downward, upward, and left right direction for at least one of stabilized hover, pitch steering and yaw steering of the aircraft.

2. The aircraft of claim 1, wherein the air-blowing steering system comprises a fan.

3. The aircraft of claim 2, wherein the air-blowing steering system comprises an air projection turret arranged with respect to the fan to direct an air stream projected by the fan.

4. The aircraft of claim 3, wherein the air projection turret is electrically adjustable to steer the aircraft.

5. The aircraft of claim 1, wherein the air-blowing steering system comprises an air turbine disposed in line with the fan in an air conveying funnel arranged in the aircraft.

6. The aircraft according to claim 1, wherein the fan is a turbo-fan.

7. The aircraft of claim 1, wherein the air-blowing steering system comprises a pressurized air tank.

8. The aircraft of claim 7, wherein the air-blowing steering system comprises an air projection turret arranged with respect to a pressurized air outlet of the tank to direct a pressurized air stream projected.

9. The aircraft of claim 8, wherein the air projection turret is electrically adjustable to steer the aircraft.

10. The aircraft of claim 1, wherein the primary electrical energy source comprises a first rechargeable battery having at least 1 kW/kg power density and at least 150 W-h/kg usable energy density.

11. The aircraft of claim 10, wherein the primary electrical energy source is repositionable within the cockpit of the aircraft for adjusting the center of gravity thereof.

12. The aircraft of claim 1, further comprising at least one back up and/or secondary electrical energy source configured to generate sufficient electricity to perform at least one of (a) powering the electric motors of the propeller units and (b) at least partially recharging the primary electrical energy source.

13. The aircraft of claim 12, wherein the at least one secondary energy source is one of a second rechargeable battery having a usable energy density of at least 200 W-h/kg, a second rechargeable battery and a fuel driven electric generator that sequentially supply power, where the second rechargeable battery has a usable energy density of at least 200 W-h/kg, and a fuel driven engine with a generator.

14. The aircraft of claim 12, wherein the at least one secondary energy source comprises a second rechargeable battery having a usable energy density of at least 200 W-h/kg, such that the aircraft is configured to fly at least 200 nautical miles at a cruise speed of up to 165 knots and at an altitude of at least 4,000 feet using only the second rechargeable battery.

15. The aircraft of claim 12, wherein the at least one secondary energy source comprises a second rechargeable battery and a fuel driven electric generator that sequentially supply power, wherein the second rechargeable battery has a usable energy density of at least 200 W-h/kg, such that the aircraft is configured to fly at least 50 nautical miles at a cruise speed of 165 knots and at [[a]] an altitude of at least 4,000 feet using only the second rechargeable battery, and at least 650 nautical miles at a cruise speed of up to 210 knots and at an altitude of up to 18,000 feet using the fuel driven electric generator.

16. The aircraft of claim 12, wherein the at least one secondary energy source comprises a fuel driven engine with a generator, such that the aircraft is configured to fly up to 1,200 nautical miles at a cruise speed of up to 300 knots and at an altitude of up to 37,000 feet using only the fuel driven engine with the generator.

17. The aircraft of claim 12, wherein the primary electrical energy source is configured to be recharged from the at least one secondary energy source.

18. The aircraft of claim 12, wherein the at least one secondary energy source is further configured to retain a preferred orientation relative to gravity as a first and second nacelles tilt.

Description

DESCRIPTION OF DRAWINGS

[0040] FIG. 1-7 present various views of an electrical VTOL aircraft according to a preferred embodiment of the invention as a 2-seater aircraft;

[0041] FIG. 8 presents a longitudinal cross section of the electrical VTOL aircraft of FIGS. 1-7 taken along a vertical plane containing a longitudinal axis of the cockpit of the aircraft

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] The present invention pertains to an electrically driven VTOL tilt-propeller aircraft 1, which may be described and referred to in the following description under the acronym E-VTOL.

[0043] The E-VTOL aircraft 1 of the invention, an example of which is represented in the appended figures, exploits advanced electric propulsion technology together with highly efficient, autonomously piloted Vertical Take-Off and Landing (VTOL) systems with pilot override. The E-VTOL aircraft 1 of the invention has been developed by the inventors with the aim of bringing the VTOL capable aircraft to a completely new status and commercial relevance and viability thanks to a tilt-propeller design relying on electrical power as energy for driving tiltable propeller units. The E-VTOL aircraft 1 of the invention accordingly offers a safe, legal, and practical flying vehicle to operate within populated, built-up localities, and to achieve speeds and ranges competitive with current fixed wing, propeller-driven aircraft of the same payload class, while less efficient rotary wing aircraft (e.g., helicopters and compounds) innately show lower lift-to-drag ratios preventing them from competing with fixed-wing, propeller-driven aircraft in speed and range.

[0044] The inventive subject matter encompasses at least three fundamentally different electric propulsion architectures (e.g., purebred battery; light hybrid; and heavy, basing-independent hybrid, etc.) which, when mechanized on advanced, high-efficiency tilt-propeller vertical take-off and landing (VTOL) aircraft, substantially expand the performance envelope, safety, or basing options over that currently available with conventional helicopters, tiltrotor and fixed wing aircraft, be it electrically or combustion powered.

[0045] The significant differentiation of the tilt-propeller aircraft 1 of the present invention compared to regular tilt-rotor aircraft known from the prior art is the massively different way of steering.

[0046] Regular tilt-rotors have two or more rotors which take over all roll/pitch/yaw steering. The tilt-propeller aircraft 1 of the invention has a steering concept like a drone and is therefore a stable platform. Instead of rotors we only operate propellers 2 with pitch steering or not. This will allows a roll steering through different propeller speeds or different propeller blade angles. The roll and yaw steering of the aircraft 1 will be done by a fenestra, fan device 3 or with pressurized air that has been produced during travel at the tail 4 or everywhere on the aircraft to provide stable hover, a smooth translation to forward speed. In regular travel speed, the aircraft 1 will be steered like a regular plane with aerodynamic rudders in any kind of configuration.

[0047] Battery energy will provide energy to have a stable take off, hover and translation to travel speed for minimum of 3 minutes. As soon as the aircraft 1 reaches travel speed, the electric engines will be switched to generators that will be propelled by a fuel driven engine of any kind and produce the needed energy to a) supply the electricity to recharge the batteries for approach and landing operation and as well the energy for the propulsion electric engines on the nacelles or it can be used as well as a purebred electric VTOL.

[0048] Myriad high energy density batteries are currently available having a wide variety of applications. Such battery technologies can be adapted for use within the disclosed subject matter. Example batteries 6 can include the BA 5590 Li-O.sub.2 battery produced by Saft Inc. having a specific energy density of 250 W-h/kg. Another example battery can include the BA 7847 Lithium-Manganese Dioxide battery having an energy density of 400 W-h/kg offered by Ultralife Batteries, Inc. It is also contemplated that Lithium-air exchangeable recyclable primary batteries based on Lithium perchloride could supply energy densities in excess of 1000 W-h/kg, where such batteries have a theoretical energy density greater than 3000 W-h/kg as discussed in Lithium Primary Continues to Evolve by Donald Georgi from the 42.sup.nd Power Sources Conference, June 2006. For example, it is also contemplated that automotive plug-in hybrid can be adapted for use with in the inventive subject matter. The batteries 6 representing the electrical energy store of the VTOL aircraft 1 can also be configured to be field-replaceable for ease of maintenance. Thus, a VTOL aircraft could carry one or more spare batteries 6, 6 that can be swapped with a failed or failing battery 6 in the field during a mission without requiring a maintenance facility.

[0049] The previously discussed propulsion systems can be applied to numerous types of aircraft markets. In a preferred embodiment, the propulsion systems can be directly applicable to rotary wing and fixed wing aircraft markets.

[0050] For example, general aviation (e.g., personal, light business, executive business, public safety, light military, light charter, and light cargo class with 1-14 total seats or at least 3500 lbs payload) aircraft would benefit from such designs by reducing noise, emissions, or other undesirable characteristics. Additionally, unmanned aviation with a gross weight of less than 20000 lbs could leverage the disclosed techniques.

[0051] One should appreciate that many other configurations for a driveline are possible, all of which are contemplated. Furthermore, one should note that the drivelines can lack cross shafts coupling the motors to the propeller, or lack a shifting gearbox as is typical in traditional combustion-based designs of efficient tilt propellers as opposed to inefficient tilt propeller aircraft (e.g., the V-22).

[0052] Combining the approaches outlined above for propulsion systems and drivelines confers many abilities or capabilities to the inventive E-VTOL aircraft 1. By providing the ability to safely achieve HOGE while under electrical power, contemplated E-VTOL aircraft 1 can be used or otherwise operate in built-up or populated arenas. The aircraft 1 has low levels of noise and low level emissions. An all-electric, quiet vertical propulsion system simply produces no unacceptable location emissions during vertical flight regime or initial climb.

[0053] An E-VTOL aircraft 1 based on the disclosed systems can provide for a market-viable purebred all-battery configuration, where the aircraft can have a range in excess of 200 nm with a vertical ascent within three minutes. Such an aircraft can also have descent and powered vertical landing reserves of at least one minute.

[0054] A heavy hybrid having a battery-only range in excess of 50 nm could operate locally to and from a logistically unsupported base. These bases are expected to provide electrical recharge energy to recharge the heavy hybrid's batteries.

[0055] Contemplated configurations also lack a requirement for a 2-speed gearbox normally required to efficiently match the large variation in required propeller RPM between hover and cruise operation modes due to poor turn-down fuel consumption of typical turbine-powered propeller with mechanical drive trains using fixed ratio gearboxes. Rather, the contemplated designs exploit the large turndown required in propeller RPM for cruise efficiency without a multi-speed gearbox.

[0056] The contemplated designs have safety exceeding that of conventional mechanical driveline rotary-wing aircraft. For example, the contemplated designs not only have a normal innate ability to provide safe auto-rotation upon loss of all drive power, the electrically propelled propellercraft hybrids can descend for controlled battery-powered hover or vertical landing after loss of a back-up and/or secondary energy/power source (e.g., larger batteries, fuel-cells, semi-cells, engine/generator, etc.). In a similar vein, hybrids can hover or land vertically using the back-up and/or secondary energy/power source should the batteries become debilitated. The electrically propelled purebred battery-powered tilt-propellers 2 or hybrid propellercraft in battery mode can perform powered hover or vertical landing after partial battery debilitation because the batteries can be split into sections for electrical isolation of a failed battery section. The same reasoning applies to elimination of the dead man's zone during take-off or landing, particularly in built-up areas.

[0057] Light propulsion motor weight (e.g., less than 0.35 lbs/shp 4-minute output) allows for installation of at least two full-lift power propulsion motors per nacelle 21. In some embodiments, a nacelle could house at least three half-lift power propulsion motors in each propeller nacelle without requiring mechanical cross-shafting to share load while under OPMI during terminal operations. Such an approach is considered advantageous in conditions where the dead man's curve or auto-rotation creates unacceptable risk in built-up areas.

[0058] Contemplated E-VTOL aircraft 1 has altitude-independent maximum continuous power from electric propulsion limited by continuous power available from the batteries 6 or from back-up and/or secondary energy/power sources 6, 6. E-VTOL aircraft lack a requirement for coupling propeller/propulsion motor RPM from a back-up and/or secondary RPM if such a back-up and/or secondary relies on rotating generators, thus simplifying design or implementation criteria. Additionally, the designs also eliminate a requirement for multiple axis thermal engine operation in hybrids, hence removing special design restrictions for multi-axis lubrication on typical nacelle mounted tilt rotor engines.

[0059] For operations in built-up areas with civilian personnel, the electric tilt-propeller aircraft 1 will, as with other rotary wing aircraft, keep disk loading below 15 lbs/sq. ft for outwash velocity reasons and propeller tip speed below Mach 0.7 at sea level in a standard atmosphere for acoustic reasons. Such a configuration allows for achieving HOGE while generating less than 60 dB of sound as measured by an observer on the ground 1500 feet from the aircraft.

[0060] FIG. 1-7 show the layout of a 2-place, cabin class, and 1650 lb gross weight tilt-propeller. The aircraft 1 is capable to hover OGE at 8000 ft at ISA +20 C. and carry a payload of 400 lb. Tilt-propeller aircraft is capable to hover for max. 8 min. (at today's battery technology) and accelerate up to 165 kt travel speed for up to 3 hours endurance before again landing configuration can be met for 8 min. The big difference to regular tiltrotor, and electric tiltrotors is the fact that a tilt-propeller aircraft has only regular pitch-propellers (instead of rotors) and the steering is made by moving air at the specific requested place to become a stable hover configuration.

[0061] FIG. 8 presents the schematic working concept of the 2-seater. Clearly visible is the way we produce the tail 4 airflow to steer the aircraft. Using as well one or more electric engines that propel a fan 3 or fenestra that can be directed into different directions (up/down/right/left/forward/backward). Additionally the electric engine 5 that is driving the fan 3 is used as a generator during travel speed.

[0062] The disclosed inventive EVTOL aircraft 1 makes strides over known art by combining various subsystems in manners that achieve unexpected results. Ordinarily, designers would avoid using a plurality of electric drive motors within a VTOL aircraft due to the complexities of de-clutching such motors from a combining gearbox after motor failure. However, the applicants have appreciated that the benefits far outweigh the inefficiencies. The complete new way of steering makes the concept completely new. We do not rely on complex helicopter kind of rotors but on regular propellers and fans.

[0063] The inventive subject matter is considered to include at least three architectures of electrically driven vertical take-off and landing (VTOL) tilt-propeller aircraft which are (1) politically compatible in safety, noise, exhaust emissions, and outwash velocity with terminal operations (powered hovering, VTOL) in densely populated built-up areas, (2) market competitive in range and speed, with existing equivalent class, fixed-wing and rotary-wing aircraft, (3) basing-independent to a degree by reliance on electric energy recharge instead of entirely on on-board electrical generators using logistic fuels, and which are variously composed of previously demonstrated, independently vetted, technically equivalent, aerodynamically efficient, lightweight airframes, efficient multi-RPM propellers, lightweight reduction gearsif any, high power density electric drive motors and generators, high energy and power density batteries, efficient lightweight engines and fuel cells, and autonomous flight management systems and multiple additional safety sensors that as well allow pilots independent flight like a drone today.

[0064] One should appreciate that presented concepts also allow for E-VTOL aircraft having the following characteristics as discussed above: An electric motor-driven, high aspect ratio (>12) tilt-propeller aircraft, with glide ratio14, cruise propeller propulsive efficiency 0.85, empty weight fraction 0.50 (absent electrical energy/power package source) A plurality of electric drive motors for each propeller with each motor of sufficient power that one propulsion motor inoperative (OPMI) will not prevent hover-out-of-ground effect (HOGE) and will allow continued HOGE without the requirement for propulsion cross-shafting, For light- hybrid electric power train architecture, sufficient rechargeable electric energy storage (e.g., battery) at 150 W-h/kg (usable) to enable 8 minutes of take-off and climb and 8 minute of landing, all at HOGE power draw, and power capacity to execute 30 second vertical landing with half electrical energy storage inoperative, all without recourse to non-stored electrical back-up and/or secondary energy/power For heavy-hybrid electric power train architecture, sufficient rechargeable stored electric energy (e.g., battery) at 200 W-h/kg (usable) to enable 50 nm range without recourse to non-stored electrical back-up and/or secondary energy/power For purebred electric power train architecture, sufficient rechargeable stored electric energy (e.g., battery) at 400 W-h/kg (usable) to enable, 200 nm range with no non-stored electrical back-up and/or secondary energy incorporated in the power architecture Propeller tip velocity0.7M, and Disk loading 15 lbs/sq. ft.