151–160 of 170 posts
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During certain hours of the day in California, electricity is essentially free due to solar overproduction, which sometimes causes negative wholesale prices.
I've never quite understood negative electric/gas/oil prices. Are you literally paid for agreeing to receive the energy?
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Specific to the electric plane, you remove some of the battery weight, as that energy would then come from the catapult. But, as a general thing? I don't see it happening. There's a TON of complexity in a catapult system. Plus, the amount of spilled champagne in first class is going to ruin a lot of suits and blouses. Can't have that. ;)
> There's a TON of complexity in a catapult system. But it's all on the ground.
But realistically you're either imparting 2G and hurting 10% of the passengers, or you may as well not bother with one. The "JATO-like" solution of a modular prop+battery unit giving you a takeoff+climb boost for 10 minutes and then heading back to the airport seems less objectionable.
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> I'd guess the actual flight time was only 10 of the 27 minutes, 30 kWh used over 10 minutes is 300kW of peak power I would note this line from the press release: > its all-electric propulsion system delivered more than one megawatt of power. I assume this was peak during takeoff.
Planes still need like half throttle to maintain altitude, that’s why airplane engines are rebuilt every few thousand hours vs lasting hundreds of thousands of miles (tens of thousands of hours) for a car engine that only uses a small fraction of its power to keep a car moving.
Yes, bit less than half, but anyway that is exactly why I said takeoff would be the peak power output.
> that’s why airplane engines are rebuilt every few thousand hours vs lasting hundreds of thousands of miles (tens of thousands of hours) for a car engine that only uses a small fraction of its power to keep a car moving.
Ratio of max power to average power is very low on the list of reasons why a gas turbine engined plane needs maintenance more frequently than a piston engined car.
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> There's a TON of complexity in a catapult system. But it's all on the ground.
Pretty sure passengers will object to being catapulted. Kids may love it though. But realistically you're either imparting 2G and hurting 10% of the passengers, or you may as well not bother with one. The "JATO-like" solution of a modular prop+battery unit giving you a takeoff+climb boost for 10 minutes and then heading back to the airport seems less objectionable.
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> There's a TON of complexity in a catapult system. But it's all on the ground.
True, but you'd need, at minimum, a well-trained crew to operate. The catapult settings vary by take-off weight. Who manages that? Does each airline run their own crew (contract) as they do other ground services? Or does the airport run it? The airframes would have be heavier, beefed up to take that load. FWIW, the Navy version of the F-35 weighs ~5000lbs more than the AF version's 29000 dry weight (granted, that's a…
Airport crew could do it based on calculated weight comunicated by pilots. With current technology it could even be automated - pull the airplane 10 m at a fixed (low) power setting, determine how fast it accelerated, calculate mass, increase power accordingly for the rest of the takeoff distance. Even an Arduino could do it.
Or simply apply the maximum force supported by the airplane's attachment point (front landing gear) no matter what the weight is.
Airframes would probably not need much strenghtening. I expect that the forces from wheel breaks are aprox. the same.
PS: With a catapult / winch launch, the MTOW could probably be increased a little - more passengers and cargo for the same flight costs.
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> There's a TON of complexity in a catapult system. But it's all on the ground.
The ground is usually where planes have their accidents.
27 mins endurance (?) for $5 of power. Not bad. I rent a 172 and have been paying a $5/h fuel surcharge for the past few months due war in Iran - but at UK avgas prices 27 mins in my plane would be $55ish. Haven’t looked into the details but kind of crazy impact on economics of aviation if this size plane (10x 172 MTOW) can actually do useful short haul
I’m thinking they got this wrong by an order of magnitude. The region they did this flight in charges ~$.25/kw. So they would have had to do the entire flight with 20kw/h or an average of 40kw of output. That’s 60hp, or about a third what your Cesnna uses on climbout. Even if you give them a very low price of $.10/kw then they are flying with less than the Cessna on climbout. Hell, a Cessna in level flight uses ~80 k…
A Dornier 328 (roughly similar in size) has two 1625 kW engines. Heart stated they "delivered more than one megawatt of power" during the flight, so maybe comparable to one of the Dornier's engines at 60% power? Even the DC-3 could take off with one engine but 60% seems iffy.
At 1000 kW and $0.10/kWh (being very generous I think), the plane would be using $100/h (at 1000 kW level) or $1.67/minute. You'd blow past $5 in 3 minutes.
I don't like that they don't share the basic numbers. It's as if they don't want folks doing the math.
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I’m thinking they got this wrong by an order of magnitude. The region they did this flight in charges ~$.25/kw. So they would have had to do the entire flight with 20kw/h or an average of 40kw of output. That’s 60hp, or about a third what your Cesnna uses on climbout. Even if you give them a very low price of $.10/kw then they are flying with less than the Cessna on climbout. Hell, a Cessna in level flight uses ~80 k…
Yeah, fully charging my EV (0-100%) at home on night-time discounted electricity of $0.07/kWh would cost me $6, so even allowing for really cheap electricity this doesn't feel right. A Dornier 328 (roughly similar in size) has two 1625 kW engines. Heart stated they "delivered more than one megawatt of power" during the flight, so maybe comparable to one of the Dornier's engines at 60% power? Even the DC-3 could take…
All FedEx express packages in my area come and go via a dedicated twin-prop plane that flies 35 miles to the hub. I'm sending a package today, and $14 of the 54$ total is a fuel surcharge. I wonder if I will be seeing electricity surcharges in the future.
> Powered entirely by batteries, X1 used approximately $5 worth of electricity during its first flight It's fun to look at the arithmetic behind this to pull out the assumptions. To lift a 25000 lb mass 1100 ft in the air requires just over 10kWh, but that's assuming no air resistance or friction, so let's triple the energy needed to 30 KWh. Let's add another 10 kWh for forward distance covered (assuming it was mostl…