Some investors have asked us how Jetoptera stands apart from competitors, particularly Joby Aviation, in the rapidly evolving aviation sector.
Joby is a public company with an equity capitalization of $4 billion. Estimated 2023 revenue is $1.3 million (Bloomberg). Jetoptera’s 2023 estimated revenue is $2.1 million. Of course, what matters is the future revenue trajectory and market scope for both companies.
Started in 2013, Joby has had remarkable success in raising money and building a working model of their tilt rotor electric distributed VTOL aircraft. However, their dependence on a battery for propulsion is a serious limitation for range, infrastructure, weight, and safety.
Jetoptera’s bladeless Fluidic Propulsion System (FPS) and aircraft technology is scalable from unmanned VTOL and STOL capable drones up to 10,000+ lbs maximum take-off weight to manned VTOL/CTOL technology. Our system uses turbocompressors driven by proven, easily certifiable turboshaft engines to feed our thrusters with the compressed air that propels the aircraft.
Our aircraft work with conventional fuel and can switch smoothly to an all-battery system when the energy density levels of the battery reach 1,000 Wh/kg, which is what is required for aerial propulsion. As for scalability, turboshaft engines (turbocompressors) exist today from 100 HP to 10,000 HP, making our scalability to larger and smaller systems completely feasible.
Jetoptera’s aircraft are a direct substitute for helicopters. Our J-4000 will be able to do helicopter missions faster and more safely, thanks to better aerodynamics in forward flight. In contrast, no eVTOL powered by a battery can match any mission of any helicopter today or for the foreseable future.
The most direct comparison is between the 5-seater Joby S4 and Jetoptera’s 4-seater J-4000 air taxi concept.
Propulsion:
The Joby propulsion system of the S4 consists of 6 electric driven propellers powered by a battery, so that half the weight of this 4000-lb vehicle is a large battery. The energy onboard this battery can be used only partially (down to 20% or so), which means that technically 20% of half the weight of the vehicle, 400 lbs is deadweight at all times. The specific energy of the battery is claimed to be 235 Wh/kg. We estimate that no business case exists for batteries with a specific energy of less than 1,000 Wh/kg, which are likely 2-3 decades out, if ever.
Jetoptera’s J-4000 will be propelled by existing turbine technology with proven performance characteristics, and FPS.
Range and cost:
EVTOL air taxis from the S4 family cannot fly longer than 15 minutes with payload. With payload, the range of the S4 is very likely 25 miles on a mission that involves VTOL at both ends, without reserves, followed by recharging at a station – offering 3-4 rides a day at most. The life of the battery that would support such a cycle would also be extremely limited and the battery would need to be replaced yearly, making the cost unaffordable and unsustainable.
Jetoptera’s J-4000 will fly up to 10 missions on a tank, with a full load, up to 500 miles range and at speeds superior to the S4, operating around the clock. The time between maintenance of a turbine of the size envisioned for the J-4000 is a proven >3,000 hrs so 2 years roughly before maintenance needs to be performed.
Speed:
The use of propellers prohibits speeds beyond 200 mph, given the tremendous power needed and the limitations of storage onboard and the wingspan needed to accommodate all the distributed electric propulsion motors and propellers. eVTOL can never reach the speeds our technology is capable of.
Jetoptera’s FPS is a jet technology. Our system produces massive entrainment of air which then is directed to produce thrust via a jet at lower velocities (250-350 mph) but with a much higher air mass flowrate. Our Adaptive FPS can revert to a "turbofan" mode, allowing on an appropriate airframe to push the limit of forward speed to up to Mach 0.8.
Noise:
The noise of the Joby is dominated by the 6 rotors/propellers. Joby reports the noise in wingborne (forward flight) and empty (no payload) as 45 dB (assuming 400 ft altitude?). Cargoless forward flight requires a minute fraction of the power needed for a full payload mission at take off or landing, when noise concerns are also greatest. Noise is proportional to the power used. Moreover, the noise from propellers is tonal, meaning that propellers chop the air at low frequencies which travel very far without atmospheric attenuation. A propeller-driven craft will be very noisy at take-off and landing for the people on the ground as well as for passengers in the cabin, no matter what powers the propeller.
The noise of Jetoptera’s system is atonal; the turbocompressor emits high frequency noise, easy to isolate and abate as it is deployed inside the fuselage, and quickly attenuated by the atmosphere. The FPS emits only broadband noise at lower jet speeds, without distinct frequencies. The overall sound levels from our system results in 25-30 dB lower than Joby's at take off and landing and at least 10 dB lower in forward flight.
Safety considerations:
- Propensity to Vortex Ring State (VRS):
VRS is a potentially deadly state associated with any tiltrotor or rotary wing aircraft, including helicopters and multirotors. In an award-winning paper, Richard Brown, of Sophrodyne Aerospace has demonstrated that eVTOLs have in fact a much higher exposure to VRS. VRS has caused several deadly crashes of the Osprey V-22 tiltrotor. Jetoptera’s FPS is not subject to VRS.
- Thermal runaway of battery:
All eVTOL companies known to us have suffered catastrophic fires originated by battery thermal runaway. The battery fire cannot be extinguished as it produces its own oxidizer and the only safety measure that can be taken is to add weight to compartment the battery units, in an attempt to isolate an onboard fire.
Along these lines, NASA's now defunct Maxwell X-57 aircraft program - not a VTOL - was an existing Tecnam aircraft retrofitted to use Joby's system of distributed electric motors and propellers. The program was stopped and canceled in June 2023 after going 3 years over the plan and 120% over budget because the propulsion system was not safe to operate. From Wikipedia: "The program had been started on the assumption that the existing electric propulsion technology was mature enough for safe flight, but that turned out to not be the case."
Footprint:
Joby’s S4 has a wingspan of 39 feet, while a General Aviation 4-5 seater can manage with less than 36 feet wingspan; the locations where the S4 can land at are limited to vertiports. The presence of rotating blades further limits access to places with cables, poles and trees.
Jetoptera’s airframe works with the FPS as an integrated system using the architecture of a box wing in order to stay more compact and access more locations than a helicopter. The J-4000 has a wingspan of less than 25 feet and, fully loaded, it weighs 1,300 lbs less than the fully loaded S4.
Jetoptera’s unique approach, centered around the versatile, efficient, and safe FPS technology, sets us miles ahead in the aviation industry.
We’re introducing a new era in aviation. Join us by investing or increasing your investment today at https://wefunder.com/jetoptera ✈️
