Airbus E-Fan X ?
Airbus E-Fan X ?
(OP)
found at Flight Global ...
opinions on this ?
To me, I don't see the sense in having an engine to generate electricity to power a motor to drive a fan.
More steps, more power conversions, less efficiency.
Unless the point is to develop the motor side of the technology to have something ready when the electrical side develops.
opinions on this ?
To me, I don't see the sense in having an engine to generate electricity to power a motor to drive a fan.
More steps, more power conversions, less efficiency.
Unless the point is to develop the motor side of the technology to have something ready when the electrical side develops.
another day in paradise, or is paradise one day closer ?





RE: Airbus E-Fan X ?
TTFN (ta ta for now)
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RE: Airbus E-Fan X ?
The BAE146 test-bed will have 3-TFEs [for safety and EE-power gen] + 1-EF [mounted on an IB strut] for RDTE.
Airbus E-Fan X First Flight to Occur in 2020 http://www.aviationtoday.com/2017/11/28/airbus-e-f...
Comment, RE recent discussion of ambient-air ducted fan power [thread http://www.eng-tips.com/viewthread.cfm?qid=432780].
GregLocock mentions thrust limits due to MACH chocking. Turbine engines run at such high internal temperatures that the speed of sound dramatically increases within the heated exit-airflow so that MACH chock occurs at much higher stream velocities... which allows much higher mass-flow-rate per engine size... hence thrust... at the cost of burned fuel. This is where electric fan-power challenge resides.
Perhaps 'prop-fan' [Unducted-Fan] technology may be the key??? https://en.wikipedia.org/wiki/General_Electric_GE3...
Regards, Wil Taylor
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RE: Airbus E-Fan X ?
The concept is, as I understand it, to have a turboprop (without the prop) ... a turbine driving a shaft to drive a generator to power a motor to drive a fan. Sure you may be able to gain something, but I can't see it being more than you'll lose with the power conversions.
another day in paradise, or is paradise one day closer ?
RE: Airbus E-Fan X ?
And then I went and did a google search and found that the above statement may be wrong. Sadly the best papers are on NTRS and dtic.mil which now appears to be inaccessible.
here's a nice graph contradicting the above, unfortunately it is CFD not real. t/h is the tip clearance
But in real tests my point remains http://4hv.org/e107_files/public/1386100085_2431_F...
figure 7 in particular., here it is
That's a bit off topic.
So having got that out of my rapidly disappearing hair, I agree that they are getting ready for a breakthrough in battery technology, but given that the efficiency of the hot part of a gas turbine is probably quite poor, particularly when cruising at lower speeds, ahha, maybe that's it. An aircraft needs a lot of thrust to take off and climb, but for optimum cruising efficiency you'd actually prefer to fly more slowly than M 0.92, but for a conventional jet there is no point in doing so since the engine efficiency drops off, so what you gain aerodynamically you lose in the engine. Other engine types, such as diesels, are quite happy to operate at part load.
I have thought of another way of achieving the same thing - switch an engine off when cruising. You'd need some way of blanking off the intake etc of the redundant engine, but that is not beyond the wit of man.
Cheers
Greg Locock
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RE: Airbus E-Fan X ?
with CFD you can show anything good, or bad ...
I thought jet engines were working at only a %age of power during cruise, whereas props are max'd out. It's one of the trade-offs between them ... maintenance ... jets are working hard for only a portion of the flight (t/o and landing), turboprops are max'd out for most of the flight.
another day in paradise, or is paradise one day closer ?
RE: Airbus E-Fan X ?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Airbus E-Fan X ?
another day in paradise, or is paradise one day closer ?