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Electric / hybrid aircraft propulsion (merged)

I am puzzled why Siemens thought they won’t make money out of it, while RR thought they can.

My view is that neither is going to make money out of it

But RR have their fingers in an awful lot of pies. For example, in the 40kt+ ferries which are now seen around the Greek islands, you find GE engines driving RR “ducted propellers”. So maybe they found something… or maybe they just want more “green” credentials and this is a great way to get green press coverage.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

I am puzzled why Siemens thought they won’t make money out of it, while RR thought they can.

I think for RR its an exercise in hedging bets, and more immediately in maintaining relationships with customers and with government agencies that are often their ultimate funding source. Those customers and agencies are doing electric propulsion R&D in order to be perceived as relevant in a ‘hot’ area – regardless of expectations for success in regard to current applications.

Siemens can now claim that they were a pioneer and transitioned the technology to an aircraft OEM… a statement which from now forward will cost them nothing.

Last Edited by Silvaire at 26 Jun 18:34

Socata are getting onto the electric act

https://www.ainonline.com/aviation-news/aerospace/2019-06-17/daher-airbus-safran-team-ecopulse-hybrid-propulsion

I would find the photoshop skills quite useful

Administrator
Shoreham EGKA, United Kingdom

An electric Caravan will be flying this year. 1000 miles endurance it seems.

That aircraft conversion is simply a proving bed for a 750HP electric engine, and makes no claims about the range or speed of that particular aircraft.

The 1,000NM range presumably comes from the sentence “electric aviation has the ability to immediately disrupt ‘Middle Mile’ transit – passenger and commercial transportation up to 1,000 miles”.

I cannot understand why reasonably intelligent and knowledgeable people like pilots continue to fall for claims, explicit or implied, that defy the laws of physics (nearly same range electric as with conventional power) or bureaucracy (“certified / soon to be certified / first next month”).

And again, the basic arithmetic:

  • According to the Cessna 208B POH, max range torque at 1,600 RPM and 10,000ft is 1,335 ft-lbs, which is 407 hp, or just above 300 kW
  • That power setting gives around 150kt TAS, so the 1000 miles will take 6 hours and 40 minutes
  • That means to fly 1,000 miles, you would need 2,000 kWh (!)
  • With a battery density of 150 kWh per tonne (e.g., Tesla Model 3) the battery would weigh more than 13 tons. Raw chemistry only, still around 7 tons
  • MTOW, however, is 4 tonnes, and empty weight around 2.1.

On the “good news” front – if you crammed in the maximum amount of batteries it could carry, you could get 300 kW and fly for an hour, which would get you 150 miles without reserve – and without payload.

Biggin Hill

Cobalt wrote:

I cannot understand why reasonably intelligent and knowledgeable people like pilots continue to fall for …

Not that difficult. They say selling private aircraft is selling dreams. This is the same principle. Without those dreamers, there would be no aircraft at all. Nothing else either for that matter.

Jim Bede understood selling aeronautical dreams to dreamers (look him up if the BD-5 saga is unfamilar) but it seems to me the difference today is a more widespread lack of critical thinking, particularly towards science and technology. It’s going to be interesting to see how the industry backs down from tens of electric aircraft projects which have no chance of succeeding based on current technology. I’m contributing to one, very interesting and it pays the bills, but the motivation for the project is the need to appear engaged with technical trends, versus anybody seeing that there is substantial untapped potential available within current technology. The little trainers might make sense, like commercial ultralights made sense for some buyers in the 80s.

Last Edited by Silvaire at 29 Jun 14:22

An electric Caravan will be flying this year. 1000 miles endurance it seems.

I am sure a Caravan can lift enough batteries to fly 1000nm but it won’t be able to carry much else, and you will need your own private fast breeder reactor to recharge the batteries after each flight

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

I am sure a Caravan can lift enough batteries to fly 1000nm

It can’t. Back of the envelope: perhaps 150 miles.

Biggin Hill

I know, I know, various “revolutionary” batteries announced to be in development and probably various more not announced, but here’s one that caught my eye:

https://www.digitaltrends.com/cool-tech/xnrgi-develops-ev-battery-tech-that-extends-range-to-700-miles/

280% increase in range for EV’s at the same weight, and fast recharge. That would put a large segment of GA on the map, in 5+ years though.

What I like about it is that there seems not to be a jump in technology, just a more effective form factor. And using “obsolete” tech from the IC industry.

Ah well, I am old enough to know that there is probably a catch somewhere. Opinions?

Last Edited by aart at 27 Jul 06:11
Private field, Mallorca, Spain
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