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

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

#161

Post by stevemadere »

mliben wrote: post #14
lambda_obrien wrote: post #10

When can we buy a motorcycle with this in it? I'm joking, but you know someone wants to kill themselves that way. On a more serious note, what other applications do you intend for these?

haha yeah, 100% I'm sure someone is already considering it... (looking at my co-founder eric, he loves motorcycles) We have received significant interest for high performance ground and marine applications, which we plan to leverage in the short-term as a way of getting lots of in-situ run-time for our technology without the hurdles of certification. We will be pursuing the long road to certification in parallel.

Also, leaf blowers and trimmers. I'd pay to have my neighbors' gas powered ones replaced.

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

#162

Post by sitkack »

martyvis wrote: post #134
sokoloff wrote: post #129

Earlier quoted context omitted.

We’ve been launching airplanes with steam catapults for many decades, albeit in an environment where we’re willing to take more risks than to go see Grandma, but many of the catapult concerns are areas where we have decades of experience and hundreds of thousands of successful cat shots.

But the catapult isn't for saving on energy that needs to be carried on the aircraft. It's simply that you can't build engines and propulsion systems on a plane with the desired takeoff weight when you have as short a runway as you do on an aircraft carrier

It is the same thing. The high power for takeoff shortens the runway from 7km to 400m.

We could do the same thing with cars and equip them with a super aerodynamic body and a 7kw engine, it could do 80kph.

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

#163

Post by car »

elihu wrote: post #65
mercurywells wrote: post #8

Earlier quoted context omitted.

> One aircraft we looked at required 30-35MW during takeoff and ~10MW during cruise. Do you envision some airframes to include assisted take-off technology? (JATO and the like, even catapults)

A simpler alternative could be to just have an electrified runway. The plane draws power from power rails embedded in a runway, or something like that. So, it doesn't switch to batteries until it's in the air. You could even have a long cable that hangs behind the plane and keeps an electrical connection until you're a few hundred feet up. (I'm picturing it connected to something like a slot-car that travels in an el…

Or how about a large battery pack that drops back to the ground after take off, eliminating it’s weight from the airframe?

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

#164

Post by toss1 »

mliben wrote: post #149
toss1 wrote: post #143

Earlier quoted context omitted.

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. Conside…

Yeah, there are a lot of factors that play into this. A couple things come to mind: 1) Considering megawatt-class machines are necessary for many future applications, the mass of the motor+inverter+gearbox (especially using best current technology) definitely adds up. 2) With a very distributed propulsion system, motors that end up near the wing tips have a big moment arm compared to the ones typically tucked under t…

Excellent point about the moment arm and control issues! I'm definitely all about maximizing power-weight and strength-weight ratios...

I am wondering about the ratios you are achieving, and about the issues of scale.

Do things get better as you scale up? I notice you mentioning the state-of-the-art at 3-4 kW/kg, and you shooting for 12 kW/kg.

This is even substantially better than small scal T-motor UAV motors at around 7w/g [1]. The chart shows them peaking at 3181W and weighing 453g.

So, I'm wondering what scale factors may be working in your favor at your scale vs the single-digit kW scale.

Also, any plans to scale slightly smaller (I'm involved in such a project)?

[1] https://uav-en.tmotor.com/html/2021/Antigravity_0119/668.htm...

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

#165

Post by mliben »

toss1 wrote: post #164
mliben wrote: post #149

Earlier quoted context omitted.

Yeah, there are a lot of factors that play into this. A couple things come to mind: 1) Considering megawatt-class machines are necessary for many future applications, the mass of the motor+inverter+gearbox (especially using best current technology) definitely adds up. 2) With a very distributed propulsion system, motors that end up near the wing tips have a big moment arm compared to the ones typically tucked under t…

Excellent point about the moment arm and control issues! I'm definitely all about maximizing power-weight and strength-weight ratios... I am wondering about the ratios you are achieving, and about the issues of scale. Do things get better as you scale up? I notice you mentioning the state-of-the-art at 3-4 kW/kg, and you shooting for 12 kW/kg. This is even substantially better than small scal T-motor UAV motors at ar…

From an active mass (electromagnetic parts, power switches, etc) perspective, our specific power is relatively consistent from 100 kW up to 1 MW. TBD on lower or higher than that.

The biggest difference is the total mass specific power (including housing, bearings, etc) usually gets worse at much lower powers (1s-10s kW), because these components become a more significant fraction of the total mass.

The 12 kW/kg number is continuous output power / total system mass (active + inactive, including motor, inverter, gearbox, housing, bearings, etc). If you isolate just the motor to compare, it is much higher than 12 :)

We do have plans to develop a ~100 kW (maybe a bit smaller) unit in the future, but when is TBD.

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

#166

Post by sitkack »

usrusr wrote: post #155
sitkack wrote: post #144

Earlier quoted context omitted.

Would you use a generator or a directly connected ICE?

Certainly not a generator, at least not unless there was some miracle fuel cell fuel. The "electric boost" would need to be completely idle most of the flight (which creates some interesting challenges regarding conversion of electric torque to air movement).

This is a fascinating analysis of hybrid electric planes

https://link.springer.com/article/10.1007/s13272-017-0272-1

I think the idea is worth exploring. Esp with superconductors an electric powertrain could have lower losses than mechanical.

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

#167

Post by usrusr »

sitkack wrote: post #166
usrusr wrote: post #155

Earlier quoted context omitted.

Certainly not a generator, at least not unless there was some miracle fuel cell fuel. The "electric boost" would need to be completely idle most of the flight (which creates some interesting challenges regarding conversion of electric torque to air movement).

This is a fascinating analysis of hybrid electric planes https://link.springer.com/article/10.1007/s13272-017-0272-1 I think the idea is worth exploring. Esp with superconductors an electric powertrain could have lower losses than mechanical.

Oh, that's sobering. All the referenced modeling seems to start with hypothetical batteries many times lighter than we have, and even then they only give minor emissions reduction hardly beyond what we are used to from e.g. succeeding generations of 737. And only under the assumption that the electricity used is completely emission-free.

And why even bother modeling constant power split? You might just as well linearly interpolate between conventional and an all-electric design and call it a day. Everything interesting about hybrid propulsion happens when the ratio is varied with power demand.

What's interesting is how much mass they account on the electric side in addition to the battery. This kind of validates H3X.

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

#168

Post by airbreather »

mliben wrote: post #94
LeifCarrotson wrote: post #85

Earlier quoted context omitted.

Copper is also 60% better in the thermal conductivity properties as well, which is another critical property. Power density in an electric motor is really based on how fast you can remove heat from the motor. I'm involved in sizing industrial servomotors, but even there you have 1s/10s/60s power ratings. I wonder if H3X can post higher power levels for takeoff, assuming it starts cold and the flight plan calls for th…

Yes, thermal conductivity is of the utmost importance at the continuous current densities we are designing for. That being said, typically the effective thermal conductivity of the winding (perpendicular to the axis of current flow) is limited by the insulation (strand and/or turn) and the encapsulation/varnish. As a result, changing the thermal conductivity of the conductors themselves will have much less impact on…

In medium to large generators the winding pitch makes a big difference, but this is also optimised for fault current (as in the winding pitch selected) depnding on the installation being compact or spread out.

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

#169

Post by hbrav »

jcims wrote: post #80
hbrav wrote: post #29

Earlier quoted context omitted.

Hey, my neighbor had a small home built plane that was powered by an old 2 cylinder generator engine. Maybe you should sell yours as generator engines too? (Yes I'm kidding. I know. I'll stop trying to trick thermodynamics.)

The funny thing is that’s a pretty common way to get three phase power from single phase supply.

Really? That's amazing.
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