Comments on: Dawn Spacecraft Shuts Down Ion Engines

By: Jay Dillon

Jay Dillon — Wed, 25 Mar 2009 00:21:33 +0000

Seversky Ionocraft, patented in the 1960s, was rated more energy efficient than small aircraft such as Cessna or helicopters. Today, with improved materials and manufacturing tech, including carbon fiber fuselage and parts, we could have not only working aircraft with "no moving parts" in the propulsion system, but also could use this same technology to power small energy efficient cars, especially if we use BlackLightPower.com high power density energy source for electric power generator onboard. (Carbon fiber manufacturing efficiency has been maximized by Dr. Amory Lovins and associates.) Just as the Woody Norris counterrotating helicopter blades are being ignored in general application, apparently, so too the Seversky Ionocraft is being totally ignored by "the big boys."

By: Valbowski

Valbowski — Sat, 22 Nov 2008 22:11:53 +0000

"Aye, Captain! Ion drive… we could learn a thing or two from that one"

By: Gavin Flower

Gavin Flower — Sat, 22 Nov 2008 19:58:43 +0000

Actually the thrust of the ion engine is so low, that it could not move a car on the surface of the Earth at all, due to static frictional forces.

However, it would cause the car to lean forward a bit, but you'd need some pretty fancy equipment to detect that – assuming we had equipment sufficiently sensitive!

-Nivag

By: Charles Vane

Charles Vane — Sat, 22 Nov 2008 15:55:12 +0000

formulaterp,

You're absolutely right, it's the high specific impulse that make's ion power so cool. I just slipped a groove for a moment…

By: formulaterp

formulaterp — Fri, 21 Nov 2008 23:02:19 +0000

"To get high efficiency, Dawn's engines sacrifice specific impulse (the 0-60 part)."

Actually the specific impulse is quite high. The ion engines however lack thrust, making them unsuitable for automobile use.

By: Charles Vane

Charles Vane — Fri, 21 Nov 2008 21:34:42 +0000

Unfortunately, if you used ion propulsion tech in cars they'd have 0-60 acceleration measured in years rather than seconds, and I for one don't want to wait that long to get home from work. To get high efficiency, Dawn's engines sacrifice specific impulse (the 0-60 part).

By: LLDIAZ

LLDIAZ — Fri, 21 Nov 2008 20:44:41 +0000

SOOOO why aren't we integrating this tech into commercial cars ?

By: watchful stone guardian

watchful stone guardian — Fri, 21 Nov 2008 19:16:11 +0000

oops. I did mean to write 0.26 kg in 24 hours! The 87 ml figure is based on 0.26 kg!

By: watchful stone guardian

watchful stone guardian — Fri, 21 Nov 2008 19:14:18 +0000

Dawn's supply of liquid xenon is about 425 kg from what I've been able to find and would take up about 142 litres of space. According to one website liquid xenon costs about US$10 per litre so the cost to fill up Dawn's gas tank is about US$1420 and this will get it about 6.3 billion kilometres of mileage. That works out to 2.3 L / 100-million km. The 0.24 kg used in 24 hours (as Nancy suggested above) works out to be about 0.087 L (87 ml), our about 1/4 of a pop can.

My Toyota Matrix can go about 600 km on a 50 L tank of gasoline (or about 8.3 L/ 100 km) at a current price of about CA$1/L. So for me to drive for 24 hours (about 2000 km) I would use about 165 L of gasoline.

So for me to drive to Ceres it would cost me about CA$525-billion (or about US$420-billion) and would take me about 8630 years and use 525-billion litres of gasoline.

So I would say that NASA is getting their time and money out of Dawn!