Found My New "and" Vehicle...and It's Electric!

[Mel]

I'm really hoping Electric drive someday gets added to the LSA parameters

When the LSA parameters were first written, the reason for limiting to a "reciprocating" engine was meant to prohibit turbines. I tried to get them to change the wording to "non-turbine" because of rotary engines, etc. But I lost that battle. Rotary engines have since been exempted from that rule and I'm sure that electric will eventually be also.

 

[Sethodine]

Well, if the lithium ion cells where the same as those in my leaf (450 lbs for 24 kw/h), then a 400 kwh pack would weigh in around 7500 lbs.

However, the article never said that it's battery was that large! It merely stated that it would have a top speed of around 400 km/h. With a range of 300 miles (482 km), that means a flight time of under an hour. For it's 320 kw motors, some guestimation on my part puts it around an 80 kwh battery pack, or around 1500 lbs. Heavy, but doable perhaps.

(Repying to myself )
I just realized my math was stupid-off. It would have a flight time of just OVER an hour, so it would need close to a 100kw/h battery (just a guess). I could be way off.

 

[NSTG8R]

Well, if the lithium ion cells where the same as those in my leaf (450 lbs for 24 kw/h), then a 400 kwh pack would weigh in around 7500 lbs.

However, the article never said that it's battery was that large! It merely stated that it would have a top speed of around 400 km/h. With a range of 300 miles (482 km), that means a flight time of under an hour. For it's 320 kw motors, some guestimation on my part puts it around an 80 kwh battery pack, or around 1500 lbs. Heavy, but doable perhaps.

Hmmm...I must have my motor math off. Assuming motors and batteries are rated at kw [hours], then a 320kw motor would wipe out a 80kw battery in 15 minutes. So 'assuming' a range of 300 miles at 180 mph cruising speed a 320kw motor [FLA] would require a 512kw battery.

I do like the concept, but batteries need to come a loooong way before can compete with good old gasoline in the "bang for your buck" category.

 

[NSTG8R]

(Repying to myself )
I just realized my math was stupid-off. It would have a flight time of just OVER an hour, so it would need close to a 100kw/h battery (just a guess). I could be way off.

Beat me to it!! You're fast!

 

[Sethodine]

Hmmm...I must have my motor math off. Assuming motors and batteries are rated at kw [hours], then a 320kw motor would wipe out a 80kw battery in 15 minutes. So 'assuming' a range of 300 miles at 180 mph cruising speed a 320kw motor [FLA] would require a 512kw battery.

I do like the concept, but batteries need to come a loooong way before can compete with good old gasoline in the "bang for your buck" category.

A 320kw motor does not draw 320kw per hour; it is capable of outputing 320kw of energy (429 brake horsepower). If the motor were working at 100% power throughout the flight profile, then it would draw 320kw in an hour of operation, but most likely it would only be drawing close to that amount during VTOL. Forward flight at cruising speed might be 50% or less, depending on how much drag you are trying to overcome. While descending to land, you might be gliding or even regenerating energy, and thus not utilizing motor power at all.

The plane would probably need to take-off conventionally (on a runway) to get the maximum 300-mile range, because of the huge energy expenditure that VTOL requires.

 

[Marshall]

This

A 320kw motor does not draw 320kw per hour; it is capable of outputing 320kw of energy (429 brake horsepower). If the motor were working at 100% power throughout the flight profile, then it would draw 320kw in an hour of operation, but most likely it would only be drawing close to that amount during VTOL. Forward flight at cruising speed might be 50% or less, depending on how much drag you are trying to overcome. While descending to land, you might be gliding or even regenerating energy, and thus not utilizing motor power at all.

The plane would probably need to take-off conventionally (on a runway) to get the maximum 300-mile range, because of the huge energy expenditure that VTOL requires.

This sounds like the mileage rating in the cars of the early eighties where they would drive 45 to calculate the Highway MPG. I'd like to know a realistic cruising range rather than an optimal.

And unless you're expecting a free fall, I suspect you never regenerate electricity in an aircraft. The goal is VTOL for both ascent and descent which would maximize power useage rather than optimize it. Nice little slight of hand.

But in a couple of decades, it might be doable if they continue improvements in electrical storage devices. Of course future advances are always subject to lengthy delays.

 

[slinches]

This thing is vaporware and there's no way it'll work as depicted. Based on the wing location, it would be completely unstable with the front pods retracted. And assuming it's equally as efficient as a Cessna Skyhawk (it'll be nowhere near that with VTOL), it would need a ~400kWhr battery pack which would weigh nearly triple the max takeoff weight of the Cessna.

ETA: By the way, they'd need substantially more powerful motors to do VTOL. A Bell 429 helicopter (7500lb max takeoff weight) needs two 625HP turbine engines, which is roughly 900kW rather than their specified 320kW.

 

[Sethodine]

This thing is vaporware and there's no way it'll work as depicted. Based on the wing location, it would be completely unstable with the front pods retracted. And assuming it's equally as efficient as a Cessna Skyhawk (it'll be nowhere near that with VTOL), it would need a ~400kWhr battery pack which would weigh nearly triple the max takeoff weight of the Cessna.

ETA: By the way, they'd need substantially more powerful motors to do VTOL. A Bell 429 helicopter (7500lb max takeoff weight) needs two 625HP turbine engines, which is roughly 900kW rather than their specified 320kW.

I'm not so sure on your stability concerns. Notice that it has no control surfaces at all, rather it uses the electric fans in the wings for computer-controlled stability. Fans could slow, rotate, or even run backwards. And if the battery is mostly in the back and the trailing wing edge, then center of lift and center of gravity could still line up just fine. This is a completely different animal from a Cessna Skyhawk.

That said, you are correct in that this is mostly just borne out of the hype for ELECTRIC EVERYTHINGZ(!) Autorotation provides a perfectly cheap and safe form of lift, but rotors just aren't as sexy as ducted fans

 

[BigWarpGuy]

I think it is way cool looking. Lilium Aviation.

 

[Marshall]

When the LSA parameters were first written, the reason for limiting to a "reciprocating" engine was meant to prohibit turbines. I tried to get them to change the wording to "non-turbine" because of rotary engines, etc. But I lost that battle. Rotary engines have since been exempted from that rule and I'm sure that electric will eventually be also.

I'm totally unfamiliar with why they wanted to exclude turbines. Isn't that pretty old technology now?