Primarily for general aviation discussion, but other aviation topics are also welcome.
By riverrock
#1705033 ... ers-crowd/

Each Mk IV Speeder will be four metres long and will weigh roughly 250kg. They are propelled by eight 50kw motors driving 60-inch blades, with power provided by swappable 500kw battery packs which can provide full thrust for around 15 minutes.

Maths seems a bit off?
8*50kW motors (so 400kW) for 15 min would use 100kWh of energy (I assume the 500kW battery mentioned is the maximum instantaneous power output so unrelated to capacity).

Highest energy/mass density rechargeable battery available at the moment is (I think) a Lithium nickel cobalt aluminum oxide at 220 Wh/kg. For a 100kWh battery, that would be (100,000/220) 454kg. The video says LiPo - its only 180Wh/kg so battery would be 555kg. Yet the whole thing only weighs 250kg? Is that 250kg without batteries?

A 250kg LiPo battery would provide 45kWh (180wh/kg * 250kg). 400kW of motors would eat that in 6min 45 seconds.

Power/Weight for an F1 car is 1.05 kW/kg. This (400kW motors, 250kg) has 1.6 kW/kg. However if the weight goes to 555kg as per batteries specified, its 0.72 kW/kg (worse than an F1 car). So they must be thinking they can get magic 100kWh LiPo batteries, plus motors, plus chassis within that 250kg.

What am I missing? Is this just all marketing?
T67M, Flyin'Dutch' liked this