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Electric Planes. Why Not? 2

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drawoh

drawoh

Mechanical
Oct 1, 2002
8,860
CA
Article on Engineering.com

The article claims that electric powered aircraft will be much quieter than heat engine powered aircraft. Is this true? I was under the impression that what I hear from an aircraft flying overhead is the propeller or the rotor(s). Modern airliners are not muffled. They use high bypass turbo-fans, one of whose benefits is that they are quieter. Am I correct?

--
JHG
 
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MikeHalloran said:
First, to avoid building a parallel infrastructure, they'd have to run on Jet A.
... which suggests Diesels.
... which typically need turbochargers at high power levels.
... so there is still a need for some high temperature metal parts.
... even without the turbos, can they be air cooled, or is the weight and complexity
of liquid cooling justifiable?
Click to expand...

I have a 1920s nautical text somewhere, that talks about how great Diesels will be shortly when they mature the design. Hopefully not a strong parallel with wide spread use of electric powered.
 
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MikeHalloran,

Any piston engine that operates over 20,000ft needs to be supercharged somehow. For commercial aviation, there is the cost of maintaining the engines, then there is the cost of a $60M aircraft sitting in the hanger not earning income.

--
JHG
 
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Just for fun, I'm trying to explore the assertion by enginesrus that recips could be competitive/ economical/ justifiable today.

Not at high altitudes. Supercharging the airframe has to add considerably to its cost, and part of the cost of idle time. Expensive airframes do not make much sense with economical engines.

Not on the same schedule as fanjets. Airscrews of any sort don't go that fast.
I had hopes for the unducted fans, but the optics of those scimitar blades have to be a tough marketing and PR problem.

Maybe they could carve out part of the market for turboprops, so no pressurization/ low altitudes, short legs, small airports, more leisurely schedules, that sort of thing.
Also subject to weather like turboprops, so a bumpy ride on many days.


enginesrus said:
there are recip engines that meet and beat the reliability of turbines in now more modern times.
Click to expand...

I'm very curious about that. I'm not in a related business. I thought state of the art in recips was a Lycoming flat four or six of fairly ancent design, nowadays with turbochargers, with a short time between rebuilds.

What did I miss?




Mike Halloran
Pembroke Pines, FL, USA
 
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MikeHalloran,

I don't select aircraft engines either.

We assume that for an aircraft, we look for high power to weight ratios and efficiency. You have a single engined aircraft. You are flying over the countryside and the engine conks out. What are the chances of you and the airframe surviving?

I suspect that those antique horizontally opposed engines are still on the market because they are reliable as all hell. All the breakability has been engineered out of them. Newer, more sophisticated engines are not to be trusted until they have been in production and use for twenty or more years.

Are you talking about supercharging the airframe, or pressurizing the airframe? DC3s are not pressurized, and I understand this is the reason they are still flying.

--
JHG
 
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Comokid,
The FAA was supposed to come up with an alternative fuel for Avgas by 2018, it is now 2018 and that fuel is not here .
the closest thing on the horizon is a 91 octane unleaded by swift fuels, but even that is not avalable for widespread distribution yet.
B.E.

You are judged not by what you know, but by what you can do.
 
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The recips I am talking about would be diesel type, and along with turbos and turbo compounding would be extremely fuel efficient. There are diesels already at the 50% point. Yes they can run on Jet fuel, and fuels you wouldn't even try to run in a jet. Aircraft speed? They already back way off the throttle to save fuel. The engines I propose would be less expensive to manufacture, and less expensive to overhaul.

Av gas is not an issue here. Though the engines could run on it.
 
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The 'recips' you're talking about would never fly.

Efficiency improvements only matter if the prime mover has a high enough power-to-weight ratio for the aircraft it's attached to to get off the ground.

The GE90 turbofans that power the 777 produce about 110,000 horsepower each, and weight about 10 tons each.

The only diesel I've ever heard of that makes that much power is the positively gigantic Wartsila that is in the Emma Maersk (and probably other ships too). It makes 110,000 horsepower too, but it weights 2300 tons.

Jets took over for a reason.

Jets are like rocket engines- the entire point is that they are light. It isn't about thermal efficiency, it's about actual work efficiency- how many pounds of cargo can an aircraft move per gallon per mile?

Jets win going away.
 
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Perhaps the [initial] key to longer-range electrical propulsion is a low-mass, low-vibration high-efficiency APU such as a Wankel rotary engine.

Why Car Lovers Are So Mad for Mazda’s Rotary Engine Revival
... ...
Back to Mazda VP Martijn ten Brink's rumor, that Mazda could use some kind of rotary engine as a range extender for an electric car. It'd make sense. Back in 2012, Mazda leased 100 Demio EV electric cars in Japan, but the car's short 124-mile range was a sore point. So in 2013, Mazda created a prototype that incorporated a rotary range extender to nearly double that range and called it the Mazda2 RE Range Extender (Mazda2 is what the Demio is called outside Japan). The prototype's wheels were driven via an electric motor, and a 0.33-liter 38-horsepower rotary engine would spool up to recharge the electric motor's batteries if they ran low and there was nowhere nearby to recharge.

Because the rotary engine couldn't power the wheels, the Mazda2 RE wasn't a hybrid like the Volt or Prius. The Wankel was more of an onboard generator that added to the car's range. The same compactness and light weight that made the Wankel a great motor for a sports car like the RX-7 also make it ideal as a range-extending generator on a car, especially one that already has electric motors and batteries competing for space and can’t afford to take on too much weight. But the range extender concept didn't make it into production, and Mazda didn't hasn't sold any electric vehicles since those 100 Demio EVs.
... ...



Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
 
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like Chevy Volt ?

But I thought rotary's were notorious for poor fuel consumption ?

And it doesn't sound like a greatly efficient engine ... to have a gas engine to run a generator to make electricity to store in a battery and use with an electric motor ?? Maybe the load on the gas engine is such that efficiency is improved, but it sounds (to me) as though you've got the inefficiencies of the gas engine in addition to the inefficiencies of the electric drive.

another day in paradise, or is paradise one day closer ?
 
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rb1957 said:
Maybe the load on the gas engine is such that efficiency is improved, but it sounds (to me) as though you've got the inefficiencies of the gas engine in addition to the inefficiencies of the electric drive.
Click to expand...

"Inefficient" is a drastic improvement over "stranded", which is what an EV is without a nearby electrical outlet.

An 'APU range extended' aircraft is, once the initial battery charge runs down, just a hydrocarbon fueled aircraft with another level of inefficiency added between engine and prop.
 
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A series hybrid is a solution normally rejected by the automotive world, in the more stringent aerospace world I wouldn't hold my breath. You are sacrificing battery capacity in order to carry the IC engine, generator and fuel. I guess you'd use the battery for takeoff and climb, then use the IC engine for cruise. Certainly feasible, technically, but complex. There may be mission profiles where it a good fit. Maybe.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
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you're only stranded if you don't plan and live with the limitations of your choice.

range extenders are "only" a marketing solution to a marketing problem ... people don't buy our car 'cause the range is insufficient, but we can't put more batteries onboard ... but we can add a portable charger.

Actually given how "dirty" it is to make batteries (particularly high energy density ones), then maybe this (gasoline engine range extenders) is a more green choice ? would diesel be "better" ? or propane ??

another day in paradise, or is paradise one day closer ?
 
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Do ekranoplans (wing in ground effect craft) operate at a lower net drag than a cruise altitude aircraft?
 
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They don't cite a source but


"
During this same year (a963), the SM-2P, which used this configuration, was built and tested. R.Ye.Alexeyev developed the first prototype of a combat ground effect vehicle. The prototype ship with a wingspan of 38 meters and a length of 92 meters was dubbed the "Caspian Sea Monster" in the West. The leviathan was lifted into the air by a dozen engines that were designed for strategic bomber aircraft.
...

The advantages of the ground effect vehicles over other types of military transport were their cost, cargo capacity and speed. The leadership of the USSR and the Ministry of Defense valued them. One of the main features of the amphibious vehicle is its invisibility to enemy radar. The prototype flew at an altitude of 4 to 14 meters (too low for radars) above the sea surface and did not touch the water during flight (and thus not detectable by sonar either). The prototype was able to carry a cargo equal to its own weight (240 tons) while expending five times less fuel than transport aircraft with similar cargo capacities.
"
 
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Siemens Electric Extra 330 Aircraft ... remarkably small 'motor' but very high power ... in an 'aggressive' aerobatic acft airframe... with about 20-minutes battery duration.

A high efficiency, compact APU that runs steady/smoothly might give it some 'real range.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
 
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Very informative website on what is happening, this subject, in the EU...


Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
 
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AvWeb Hydrogen Fuel Cells Go Flying

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
 
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WKTaylor,

Shades of Griffon engined Spitfires!

That thing is not electric. It is a hybrid. I wonder what the advantage is of a hybrid aircraft?

--
JHG
 
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