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Would it be possible? - A fifth mode of transport...

by Jackthedon
Tags: mode, transport
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Ryan_m_b
#19
Apr24-14, 07:56 AM
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Quote Quote by X338 View Post
It's a valid idea actually. If one used ionocraft technology properly scaled up and integrated it into aircraft it could work as an air taxi service. Sort of like a flying car. And GPS could be used for navigational support.

Welcome to the forums. An ion drive and an ionocraft are not the same. In any case have you done a calculation to determine the necessary size of a man rated ionocraft? I bet it would be extremely prohibitive.
X338
#20
Apr24-14, 10:29 AM
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Yes an ion drive has a lower density thrust since the propulsive mass is ions, that's why its use is limited to space propulsion applications that don't require high velocities.

Anyway MIT did a study last year on ionocraft and found that they're a method of propulsion that's 50 times more efficient than Jet Engines.

http://newsoffice.mit.edu/2013/ionic-thrusters-0403

And given that it's such a potentially revolutionary propulsion technology with no moving parts it's surprising that few in academia or industry have seriously researched it.
cjl
#21
Apr24-14, 01:03 PM
P: 1,018
Quote Quote by X338 View Post
Yes an ion drive has a lower density thrust since the propulsive mass is ions, that's why its use is limited to space propulsion applications that don't require high velocities.

Anyway MIT did a study last year on ionocraft and found that they're a method of propulsion that's 50 times more efficient than Jet Engines.

http://newsoffice.mit.edu/2013/ionic-thrusters-0403

And given that it's such a potentially revolutionary propulsion technology with no moving parts it's surprising that few in academia or industry have seriously researched it.
That's one of those headlines that is misleading at best - it's simply stating the well known fact that for a given amount of thrust, you use less power if you have a higher mass flow rate with a lower exhaust velocity. It's the same reason propellers are more efficient than jet aircraft at low speeds, and why turbofans are more efficient than turbojets at moderate speeds. You can gain a similar benefit though by simply using a really large propeller powered by a turboshaft engine, and I'd be curious to see how their ionic wind craft compares in efficiency to something like a helicopter main rotor, which also uses the principle of moving a very large volume of air.

(Also, using something like this with a very large mass flow rate and a low exhaust velocity does give you a good static thrust per watt, but it isn't very good as soon as you actually want to go somewhere - with a very low exhaust velocity, your top speed is quite limited)


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