mliben

5 ms·

1.
by mliben 6y ago
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 (inc
2.
by mliben 6y ago
In general, Magnax seems to be focusing on automotive, which changes the driving factors in the design significantly (partial load efficiency becomes very important, cost is #1, etc). In the aircraft world, Magnix has been doing some really
3.
by mliben 6y ago
On Wisconsin!
4.
by mliben 6y ago
Yes, this is one variation of what is referred to as "in-slot cooling". Keep in mind that putting coolant inside the slot removes precious conductor cross-sectional area. There is a tradeoff to be analyzed, and in some situations
5.
by mliben 6y ago
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 tec
6.
by mliben 6y ago
Using the simple drag polar approach, D = A*v^2 + B/v^2 (D is total drag, first term is parasitic drag, second term is lift-induced drag) dD/dv = 0 where v = (B/A)^(1/4) Plug in v = (B/A)^(1/4) D = sqrt(AB) + s
7.
by mliben 6y ago
We are definitely saying the same thing in very different ways. Just using the drag polar approach and neglecting second-order effects (assume negligible dependence on Re, sufficiently subsonic so negligible impact of M, and linear lift coe
8.
by mliben 6y ago
Yep! SiC was part of the design DNA from the beginning.
9.
by mliben 6y ago
Definitely, for sure. Like I said in the other thread, supersonic is a whole other thing, and I don't think anyone is trying to electrify anything supersonic any time soon :)
10.
by mliben 6y ago
It's a common misconception that different ways of connecting and/or driving coils can emulate a CVT, multi-speed gearbox or single speed gear reduction. The maximum continuous torque of a motor is purely a function of the maximum
11.
by mliben 6y ago
a LOT of energy is required to fly supersonic- IMO the energy storage side (battery and/or hydrogen fuel cell) has a long way to go to make supersonic flight remotely feasible.
12.
by mliben 6y ago
Yes, the range-optimal speed is where the parasitic drag is equal to the lift-induced drag. If you go through the analysis, the air density drops out of the range equation if you assume are operating at the range-optimal speed (which is h
13.
by mliben 6y ago
To add to what Jason said- The characteristic current of the machine is roughly the same as the maximum inverter current, so at maximum power the power factor is between 0.7-0.8. This also means the flux weakening capability (CPSR) of the m
14.
by mliben 6y ago
Tight integration removes an entire housing and cold plate from the inverter design (++ specific power). Allowable SiC die temperatures are ~175 C these days, which is pretty awesome. The inverter and motor are on opposite sides of the cool
15.
by mliben 6y ago
The phenomenon is due to Paschen's law (there is a good wikipedia article on it). The breakdown potential of a gas is minimized at some pressure, and in the case of air, that pressure is < 1 atm, and corresponds to a specific altitu
16.
by mliben 6y ago
Less dense air -> higher angle of attack required to produce required lift -> true lift vector is more offset from vertical -> horizontal component of lift is actually producing drag Like I said in the other comment, if the plane i
17.
by mliben 6y ago
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 limi
18.
by mliben 6y ago
Aluminum has the best conductivity/mass out of all of the common conductors. Motors are actually more volume constrained than mass constrained for the windings, which is why copper is typically used there instead.
19.
by mliben 6y ago
Ampaire (among others) is already making great strides in general aviation. With significant improvements in specific energy (see QuantumScape, HyPoint) and specific power improvements (what we are working on) coming in the next few years,
20.
by mliben 6y ago
For our technology demonstrator, we have a pretty small rotor. Future direct drive designs (typically higher power as well) will have much larger diameters. I can't be too specific, but you can probably get an idea of the rotor size fr
21.
by mliben 6y ago
Certainly. Infrastructure is actually one of the biggest technological challenges for flight electrification. This is one area where hydrogen / fuel cell might have a leg up since it can physically/geographically decouple the powe
22.
by mliben 6y ago
Well, you would need significant energy storage either in the form of batteries or hydrogen + fuel cells as well :) Our technology demonstrator is a 250 kW machine, but we have plans to scale up to the megawatt class in the next few years.
23.
by mliben 6y ago
A simple physics-based plane model (like the one we made to understand vehicle-level impact of our technology development) dictates that the range-optimal cruise speed is proportional to 1/sqrt(air density), so it makes sense that the
24.
by mliben 6y ago
Silver is crazy expensive compared to copper, and the tradeoff isn't worth 6%. Also, 3d-printing pure copper is relatively new, and I'm not sure there is as much of a business case for 3d-printing silver (from the perspective of t
25.
by mliben 6y ago
Not exactly what Talyn Air is doing, but along the same lines- separating out the "lift/climb" vehicle from the "cruise" vehicle. It can actually be a very compelling design!
26.
by mliben 6y ago
We take the 80/20 approach here. We start with analytical design (can be done pen on paper, but typically happens in excel/etc) to get a high-level view on the "continent" of design possibilities. This can be done readil
27.
by mliben 6y ago
Absolutely. It's easy to focus on comparing what we are working on with the other (few) electric solutions being built out there, but compared to combustion engines the specific power is a big step change. When you combine that with im
28.
by 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
29.
by mliben 6y ago
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
30.
by mliben 6y ago
I think most forms of assisted takeoff technology would reduce electrical power requirements for takeoff, but not put much of a dent in the climb power (unless you can catapult/ JATO all the way up to cruising altitude, which would be

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