Rolls-Royce's all-electric airplane smashes record with 387.4 MPH top speed | Hacker News Reader

Rolls-Royce's all-electric airplane smashes record with 387.4 MPH top speed

engadget.com

26 pointsnoyesno13 comments

Both the style and purpose of Spirit of Innovation remind me of the Mew Gull, a pre war King’s Races winner with the side goal of beating the Luftwaffe to having the fastest aircraft:

https://en.m.wikipedia.org/wiki/Percival_Mew_Gull

What's the all-important figure: Maximum flight distance?

In practice though, it's maximum minutes as many planes will be taxiing then need to sit on the tarmac for quite a while waiting for take-off, and taxiing and loitering after landing till it can reach the terminal.

I’ve never heard of a 750 volt motor. What’s the deal with that? How do they even get the voltage that high?

Two 12-volt sources in series yield 24 volts to the circuit.

Lol

How do they even get the voltage that high?

The same way as any other battery, just increase the number of cells. Most cells seem to run between 1.5-2 volts. A 12 volt car battery is usually six cells of 2 volts each.

For the motor: A lot more insulation on the coil windings mostly. Higher voltage usually means less copper needed and more insulation. Boosting voltage from batteries is pretty easy. Either using a transformer on the motor controller or putting enough cells in series to get the voltage you want. There are also methods using inductors and PWM to get a boosted voltage.

750 volts is actually fairly low. Siemens makes some 3-6 kilovolt HV motors. https://hv-easy.azurewebsites.net/

What happens if they get struck by lightning?

In a day dream, it'd charge the batteries!

I'd call it the Static Energy Recovery System (SERS)

Is it quieter? Serious question.

Probably. Engine noise would be much lower, but prop noise would be the same.

Most noise from prop planes comes from the propeller. You can make some pretty quiet prop planes though. Especially if you use lots of smaller propellers. However for a race plane you can bet this thing is loud as heck.

Reply on news.ycombinator.com