17 ms·

Launch HN: H3X (YC W21) – High power density electric aircraft motors

229 points by jjsylvestre 6y ago

Hey HN! I’m Jason, one of the co-founders at H3X (https://www.h3x.tech https://www.h3x.tech). We are building the lightest electric propulsion systems in the world. Our first product is a 250kW (330HP) integrated motor drive in a 18kg (40lb) package. It combines the electric motor, inverter, and gearbox into a single unit, resulting in an ultra-high-power density solution for electric aircraft (and other mass sensitive applications). In terms of electrification, we believe the aircraft industry is where automotive was ten years ago. There are many companies working on eVTOL and single-seaters, but very few are working on large commercial single-aisle electric aircraft such as a 737. This class of aircraft is absolutely critical to electrify as it accounts for the most passenger-miles [1] and is the biggest slice of the pie in terms of aviation emissions. Beyond the environmental impact, there are huge potential cost savings from both fuel (or lack thereof) and reduced maintenance for airlines. Aircraft are very mass sensitive so there are two main technology challenges that need to be solved to enable this class of electric aviation – (1) High energy density and efficient energy storage (batteries, hydrogen fuel cells, etc.) (2) Light, efficient, and high-power density electric propulsion systems (electric motors, power electronics, gearbox) There are many people working on (1) and great strides are being made [2][3]. We are focused on solving (2). A study done by the DOE determined that for a 737 to complete a five-hour flight, the propulsion system must be >12 kW/kg [4]. Today, best-in-class systems have a power density of 3-4 kW/kg. With our first product, we are targeting 13 kW/kg, making it an attractive solution for near-term Advanced Air Mobility (AAM) applications as well as an enabling technology for the aviation industry to enter the next stage of electrification. There are some cool things we are doing with the electromagnetics, power electronics, and the integration between the systems to get to the 13 kW/kg. There is not a single magic bullet, but rather a combination of multiple technological advances - 3D printed copper stator coils, high frequency SiC power electronics, and a synergistic cooling system to name a few. Our origins in electrification stem back to our college days where we built Formula-style electric racecars (s/o to Wisconsin Racing FSAE!). During year 1 of the program, we got so fed up with our COTS motors and inverters, we decided to go clean slate and build our own from the ground up the following year. Those were super happy fun times. Lots of dead IGBTs and all-nighters in the shop, but in the end, we got everything working and delivered! It was a true test of resilience and taught us how to GSD. Great preparation for starting a company. This led us to grad school and it became apparent during this time that the electric aircraft industry was a sleeping giant ready to be woken. We felt uniquely positioned to capitalize on this opportunity, so after about a year in industry, we left our full-time jobs and went all in. We’ve got a long road ahead - aviation is tough, there’s no denying that. In addition to the engineering challenges, there are also major certification barriers. However, CO2 is a serious problem and right now the major aviation players don’t have a compelling plan to meet the goals laid out in the Paris Agreement. Innovation needs to come from the outside and that’s what we’re doing at H3X. I’d love to hear your guys thoughts and would be happy to answer any questions you have. Sources: [1] https://www.transtats.bts.gov/tables.asp?DB_ID=130 https://www.transtats.bts.gov/tables.asp?DB_ID=130 [2] https://www.theverge.com/2020/9/22/21449238/tesla-electric-car-battery-tabless-cells-day-elon-musk https://www.theverge.com/2020/9/22/21449238/tesla-electric-c... [3] https://hypoint.com/ https://hypoint.com/, https://www.plugpower.com/ https://www.plugpower.com/ [4] ASCEND DE-FOA-0002238

tlb 6y ago
Given that the batteries weigh a lot more than the motors, I would have thought that motor efficiency (which scales battery size) was much more important than motor weight. My back-of-the-envelope is: - Assuming 0.4 kWh/kg for batteries, and they have to run for 4 hours, then the total mass per kW is 10 kg (batteries) and 0.08 kg (motor). - A 1% increase in motor efficiency could eliminate 0.1 kg of batteries, which would let you double the weight of the motor. - (My analysis is invalid if you need much higher peak power than cruise power.) I'm curious how you optimize the entire system for such trade-offs.
- audunw 6y ago
  > Given that the batteries weigh a lot more than the motors, I would have thought that motor efficiency (which scales battery size) was much more important than motor weight. I guess that depends on what kind of airplane you are making. If you're just making the same kind of airplanes we've been making with ICE, but with electric motors and batteries instead, you're probably right. But if you're making an electric airplane from scratch, there's a lot you can do if you have a really light motor, which can drastically reduce drag. Look at Maxwell X-57 for instance: https://www.youtube.com/watch?v=-HvZ7c0F9ik https://www.youtube.com/watch?v=-HvZ7c0F9ik If you're going to have lots of motors on the wings, they better be as light as possible. I'm guessing the increased efficiency from a design like that can easily be as important as the efficiency of the motor itself.
  - mliben 6y ago
    These are all great points- everything is very interconnected in these vehicles, and there is a lot of potential upside in high power density distributed propulsion (like on the Maxwell). In characterizing the vehicle-level benefit of power density, it is definitely important to consider the X kg of structure required to support 1 kg of motor/inverter/gearbox/etc.
    - toss1 6y ago
      Excellent points about associated structures! However for the motors, isn't it the case that the support structure design is dominated by the thrust loads, which should vastly exceed the motor mass? For sure, there is some non-thrust-related structure to react the motor's mass, e.g., inertia from a harsh landing, but how much extra is it? This is much more the case with power/mass optimized motors like yours. Consider an ideal case - you achieve the same power with negligible mass, say 1kg. How much structure in my aircraft using your motor could I really eliminate vs your current model? And the real case, switching from a competitor's similar-power motor to yours, how much additional structure weight can I save by switching, beyond the obvious great advantage of your motor's weight savings? (Obviously, these answers massively depend on other factors, but... )

229 points by jjsylvestre 6y ago

tlb 6y ago

Given that the batteries weigh a lot more than the motors, I would have thought that motor efficiency (which scales battery size) was much more important than motor weight. My back-of-the-envelope is: - Assuming 0.4 kWh/kg for batteries, and they have to run for 4 hours, then the total mass per kW is 10 kg (batteries) and 0.08 kg (motor). - A 1% increase in motor efficiency could eliminate 0.1 kg of batteries, which would let you double the weight of the motor. - (My analysis is invalid if you need much higher peak power than cruise power.) I'm curious how you optimize the entire system for such trade-offs.

audunw 6y ago
> Given that the batteries weigh a lot more than the motors, I would have thought that motor efficiency (which scales battery size) was much more important than motor weight. I guess that depends on what kind of airplane you are making. If you're just making the same kind of airplanes we've been making with ICE, but with electric motors and batteries instead, you're probably right. But if you're making an electric airplane from scratch, there's a lot you can do if you have a really light motor, which can drastically reduce drag. Look at Maxwell X-57 for instance: https://www.youtube.com/watch?v=-HvZ7c0F9ik https://www.youtube.com/watch?v=-HvZ7c0F9ik If you're going to have lots of motors on the wings, they better be as light as possible. I'm guessing the increased efficiency from a design like that can easily be as important as the efficiency of the motor itself.
- mliben 6y ago
  These are all great points- everything is very interconnected in these vehicles, and there is a lot of potential upside in high power density distributed propulsion (like on the Maxwell). In characterizing the vehicle-level benefit of power density, it is definitely important to consider the X kg of structure required to support 1 kg of motor/inverter/gearbox/etc.
  - toss1 6y ago
    Excellent points about associated structures! However for the motors, isn't it the case that the support structure design is dominated by the thrust loads, which should vastly exceed the motor mass? For sure, there is some non-thrust-related structure to react the motor's mass, e.g., inertia from a harsh landing, but how much extra is it? This is much more the case with power/mass optimized motors like yours. Consider an ideal case - you achieve the same power with negligible mass, say 1kg. How much structure in my aircraft using your motor could I really eliminate vs your current model? And the real case, switching from a competitor's similar-power motor to yours, how much additional structure weight can I save by switching, beyond the obvious great advantage of your motor's weight savings? (Obviously, these answers massively depend on other factors, but... )