Elon Musk says he is close to working out how to build an electric jet which would take off and land vertically. The Tesla boss revealed his plans during a question-and-answer session at the Hyperloop Pod competition in Texas.
During an interview with Marketplace in October 2015, Musk said: “I do like the idea of an electric aircraft company. I do think one could do a pretty cool supersonic, vertical-take off and landing electric jet. That would be really fun.”
When asked if he was just making things up, Musk said: “No, I have a design in mind for that, but I have too many things on my plate to do, and then of course there is the Hyperloop.”
In 2014, Musk also mentioned his electric plane ideas during an interview with the Massachusetts Institute of Technology (MIT), when he said he was “toying” with the concept, adding: “I would love to do it, but I think my mind would explode.”
Musk’s comments come in the same week which saw budget airline EasyJet announce it is looking at producing hybrid electric airliners. The plans describe a kinetic energy recovery system (Kers) similar to that used by Formula One cars, where energy created by braking when landing would be stored in a battery and used to run and even taxi the plane without using its jet engines.
Airbus vertical takeoff and vertical passenger electric planes
There was an EADS (Airbus) Voltair design for a vertical takeoff and vertical passenger electric planes. Elon Musk has talked about creating a supersonic certical takeoff and vertical landing electric passenger plane. This would enable airports without runways to be in cities.
The EADS all electric passenger plane design depends upon batteries achieving 1000 watt hours per kilogram and superconducting engines being developed. High temperature superconducting motors are expected to reach power densities of 7-8 kW/kg with almost no electrical losses. This compares to 7 kW/kg for today’s turboshaft engines. An essential requirement for the VoltAir concept is to have a light and low-drag airframe. Advanced carbon fiber composite materials are used, and an unconventional configuration with an optimum fuselage thickness-to-length ratio is selected to minimize aerodynamic drag while providing a maximum useful internal volume. The fuselage’s generous volume is used for a better integration of the landing gear, significantly improving the aerodynamic properties of the wing-to-fuselage junction.
Distributed small electric engines and batteries that also acted as part of the structure of a plane (as body panels) could be innovations that Elon Musk has for enabling commercially interesting electric passenger jets.
EADS is a global leader in aerospace, defense and related services. In 2010, the Group – comprising Airbus, Astrium, Cassidian and Eurocopter – generated revenues of € 45.8 billion and employed a workforce of nearly 122,000.
In 2014, Aviation Week talked about a patent for a VTOL supersonic plane. Richard Lugg is the man behind the HyperMach [Mach 4 cruise] SonicStar supersonic business jet concept. HyperMach’s design has supersonic laminar flow, plasma drag and boom reduction, and superconducting electric propulsion. Lugg’s name appears on a new US patent (8,636,241, filed in 2006) for a hybrid jet/electric VTOL aircraft.
Elon Musk, the billionaire behind PayPal and SpaceX, has suggested that his next big project could be a supersonic vertical take-off passenger jet.
There is battery technology which would greatly increase the energy density (watt hours per kilogram) of batteries. This will make the supersonic electric passenger plane feasible.
Patent 8636241 – A fixed-wing VTOL aircraft features an array of electric lift fans distributed over the surface of the aircraft. A generator is (selectively) coupled to the gas turbine engine of the aircraft. During VTOL operation of the aircraft, the engine drives the generator to generate electricity to power the lifting fans. Power to the lifting fans is reduced as the aircraft gains forward speed and is increasingly supported by the wings.
The design uses electric-powered lifting fans in the wing roots and canard foreplanes for vertical flight. The fans are powered by electricity generated by turbofans, which provide propulsion in forward flight. In vertical flight, residual thrust from the turbofans is vectored downwards to supplement lift from the fans. In forward flight, all engine power goes to thrust and louver doors close over the fans.
How much engine thrust needs to be vectored depends on the power of the lifting fans, which can range from 25% to 100% of the lift needed for VTOL, the patent says. The advantage of the fans is their exhaust flow is at ambient temperate and low velocity. The power extracted from the turbofans to generate electricity also reduces the temperature and velocity of the vectored engine thrust, allowing the aircraft to operate from unprepared surfaces.
In 2013, HyperMach was reported to be talking to two or three aircraft manufacturers about the production of the SonicStar.
“We are now speaking to one US manufacturer and another manufacturer outside of the US,” said Richard Lugg, CEO. “We are also speaking to an Asian manufacturer, although that has not progressed to a face-to-face meeting as of yet.”
Having made some changes to the aircraft in the last couple of years, the original entry date has now been pushed back from 2021 to June 2024.
“We have made some improvements in the turbine, where we generate the power, says Lugg. “We have increased the maximum capacity from 24 to 32 and brought the cruising speed up to around 3000mph.”
HyperMach is designed to be a fully integrated hybrid supersonic, non-afterburning engines, hybrid aerodynamic double delta supersonic laminar flow wing design, pressurized cabin to 84,000 ft, custom-luxury cabin and pilot deck, 6000 nautical miles IFR capable range, Jet-A, JP-4 and JP-7 fuel capable, electromagnetic drag reduction technology affording dramatic reduction/elimination of sonic boom below 0.25 lbs/sq.ft., overland Mach 4.0 cruise.
Operational requirements; Hot and High altitude day conditions and landing distance 4800 ft, Class 4 operational acoustics condition compatible,
Performance requirements (Mach 4.0 / 10 – 20 passengers, 60,000 ft)
HyperMach Engine / Propulsion System
The SonicBlue vision is the development of revolutionary engine design to fundamentally change the way aero gas-turbine engines operate in order to significantly improve the performance of aircraft systems.
* Hybrid engine technology developed to offer a highly efficient, supersonic, variable bypass fan ratio engine design.
* The engine operates electrically by generating a large amount of on-board electric power through its superconducting electric turbine ring generator system.
* Engine produces sufficient power to operate the multi-stage counter rotating, superconducting, dual ring motor electric bypass fans and superconducting electric ring motor axial compressor, power generation and thrust comes from 5-stage superconducting axial turbine.
* The 54,700 thrust class S-MAGJET engine (two engines) described is optimized to fly the HyperMach SonicStar aircraft at 62,000 ft, at a specific fuel consumption below 1.05 at Mach 3.3, this performance will be unprecedented and will welcome in a new era of the future of aerospace transport.
* Electrical generation is provided by superconducting ring generators that are powered by the high velocity exhaust thrust from the combustor section of the engine.
* The bypass fan is a twin fan system in which one fan counter rotates with the other fan, which reduces aerodynamic swirl and drag.
* The bypass fan configuration is not constrained by a drive shaft, heavy gears and complex gear boxes, nor complex lubrication systems and it can be run at an optimal rotational speed so as to maximize its efficiency at any aircraft velocity, or altitude.
* The bypass fans running independently from the compressor can be run at much slower speeds than the compressor, this means a more efficient RPM for the fan blade design of the S-MAGJET, a low bypass fan supersonic engine design.
* Lower operating RPM speeds afford the use of wider blades, raising aerodynamic efficiency and thrust per horsepower, making the engine architecture greatly more efficient than the current art of engine designs.
* Light weight superconducting ring motors with integrated cooling for the compressor do not require a drive shaft, nor the bypass fans or the superconducting ring generators of the power turbine, a “hollow-core shaft-less” tunnel is left in the center of the hybrid electric turbine which now carries additional bypass air.
* Bypass air as the major component of thrust, rather than the hot exhaust from the power turbine being utilized as thrust is a more efficient method of producing thrust for propulsion in turbines.
* Supersonic-Magnetic Advanced Generation Jet Electric Turbine (S-MAGJET), the majority of electric power produced off the power turbine via the superconducting ring generators is directed forward through a proprietary electric power management system to run the electric bypass fans and the electric compressor. This electrical independence of the bypass fan from the multi-stage axial compressor raises overall efficiency of the engine by 70% alone.
Super Batteries, Superconductors and distributed small engines
The superconducting engines seem to be farther away but appear to be feasible. Superconducting wire will be scaling up production and getting to lower cost over the next few years and continuing to improve in production volume and costs over the next decades. In 20 years, the superconducting engines with 7-8 kw/kg or better could be achieved.
All Superconducting motors could be three times smaller
Superconducting generators have already been demonstrated to exhibit power densities in the range of turbine engines thus validating the feasibility of future ultra lightweight machines for airborne applications.
Distributed Multi-Fans Driven by Few Engine Cores
Distributed propulsion employing multiple propulsors driven by a few fuel-efficient engine cores has been studied and is being pursued under NASA’s SFW N+3 project
* Gas-Driven Multi-Fans
* Gear-driven Multi-Fans
* Electrically Driven Multi-Fans
The following possible benefits of distributed propulsion concepts have been identified through various studies mentioned in previous section:
• Reduction in fuel consumption by ingesting the thick boundary layer flow and filling in the wake generated by the airframe with the distributed engine thrust stream.
• Spanwise high lift via high-aspect-ratio trailing-edge nozzles for vectored thrust providing powered lift, boundary layer control, and/or supercirculation around the wing, all of which enable short take-off capability.
• Better integration of the propulsion system with the airframe for reduction in noise to the surrounding community through airframe shielding.
• Reduction in aircraft propulsion installation weight through inlet/nozzle/wing structure integration.
• Elimination of aircraft control surfaces through differential and vectoring thrust for pitch, roll, and yaw moments.
• High production rates and easy replacement of engines or propulsors that are small and light.
Next Generation More-Electric Aircraft: A Potential Application for HTS Superconductors (14 pages, 2008] Fully superconducting machines have the potential to be 3 times lighter.
Other discussions of Supersonic electric planes
Faster Supersonic Flight
The electrically powered engine that could theoretically propel an aircraft to a flight speed of Mach 1.5 could be modified to operate at higher speed. The engine intake would be modified to an “Oswatitsch” design with variable geometry. That design would generate (weaker) oblique shock waves at the entrance to the engine as well as be able to “dump” excess air or duct in extra air depending on flight conditions.
The faster engine may use a single-spool axial flow compressor that has more pressure ratio (up to 15 to 1 with variable stator blades) to raise air temperature. The aircraft may carry water in special tanks and electrolysis gear to generate hydrogen that may be injected ahead of the nozzle of the engine. The combustion of the hydrogen would increase the air temperature and raise the exit velocity of the gas that leaves the engine. Flight speeds of Mach 2 to Mach 2.4 may be possible.
VTOL in Fiction
There have been vertical takeoff landing (VTOL) planes in fiction.
Avengers Quinjet is VTOL but no mention of it being an electric plane. It is supersonic
The “Bus” is a VTOL plane used in the TV show Marvel Agents of Shield. But it appears to be a subsonic C17 with VTOL. Again no mention that it is electric powered.