Thrust

Cryticfarm · Post by **Cryticfarm** » Sun Sep 21, 2008 3:50 pm

shadowkhas wrote:
Cryticfarm wrote:Well, the problem is that fuel takes up space, which means more weight, which means more fuel to carry that weight, which requires more weight, thus needing more fuel :\.
But it's a solveable problem, unless he wants to go at the speed of light.

Who said he didn't :p.

Aumaan Anubis · Post by **Aumaan Anubis** » Sun Sep 21, 2008 6:32 pm

Duration, people. Duration.

Not speed.

Yodel · Post by **Yodel** » Sun Sep 21, 2008 6:42 pm

ScramJet.

Problem solved!

valdark · Post by **valdark** » Sun Sep 21, 2008 6:51 pm

http://www.brookings.edu/articles/2008/ ... inger.aspx

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 2:17 pm

valdark wrote:http://www.brookings.edu/articles/2008/ ... inger.aspx

That would've been a nice step had they explained how they intend to power all of it.
Or if they'd even mentioned something related to jetpacks...thrust... or flight...

Dr.Cox · Post by **Dr.Cox** » Tue Sep 23, 2008 2:29 pm

Aumaan Anubis wrote:OK, now for the non-philosophical more scientific question.

In the aspect of rockets, they carry millions of pounds of fuel to generate enough thrust to carry a human into space. This fuel lasts only a few minutes.

Now, I doubt that many of us are physics majors, but how would one go about generating thrust to carry a person, but for quite a bit longer?
Like, lets say, half an hour.

Is there a type of fuel composition that burns slowly, but releases large amounts of energy, enough to carry a person?

I hate to back up on this, but the best example I can give is Iron Man. I know, I know, shutup
But he's got a suit that sorta molds around him, but he's still somehow got enough fuel to last him quite awhile during flight.

Again, is there a fuel last burns slow, but generates that thrust needed?
Or, really, do you need all that much fuel? Because in a rocket, the fuel is also carrying a ship. And I'd only be looking, hypothetically, to carry about 65 kilograms.
Again, thirty minutes, 65 kilograms.

Iron Man uses a Beta particle generator to power his suit.

The problem is that lifting a full-grown person 100 feet into the air considerably increases their potential energy, and that gain in energy must come from the stored chemical energy in the jet pack. Ditto for the energy required to zip around once airborne. You just can't store enough energy to make long flights without making the suit too big to wear. So jet boots alone don't make Iron Man an escapist fantasy, but the idea that Stark could store enough energy in his suit to fly for more than half a minute does.

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 2:39 pm

Dr.Cox wrote:Iron Man uses a Beta particle generator to power his suit.

The problem is that lifting a full-grown person 100 feet into the air considerably increases their potential energy, and that gain in energy must come from the stored chemical energy in the jet pack. Ditto for the energy required to zip around once airborne. You just can't store enough energy to make long flights without making the suit too big to wear. So jet boots alone don't make Iron Man an escapist fantasy, but the idea that Stark could store enough energy in his suit to fly for more than half a minute does.

Well, my current "design" would allow for 4 seconds of flight, and 618 meters into the air. Fun, eh? Except it all comes from a chemical, unsymmetrical dimethylhydrazine, at that.
But that also makes for 4 seconds falling back down... 618 meters

But I've asked in passing about beta particle generators, and they wouldn't really work. I think that it's because that most beta particles that are emitted from the sun aren't able to successfully reach Earth's surface.
Maybe I'll do some more research on them.

But that does sorta remind me of the fact that I can't store enough chemical energy(like dimethylhydrazine) to sustain for even 10 seconds, let alone a long-term flight.
I guess I should focus on some type of energy source that is continually replenished throughout flight.

Yodel · Post by **Yodel** » Tue Sep 23, 2008 2:46 pm

Again, SCRAMjet.

That's really the first step you should take before trying something based on a controlled explosion. Strapped to your ass.

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 2:49 pm

...well lets see. I didn't really look at it since the other guy provided a link and you didn't, but as Wikipedia says...

"A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the distinction being that some or all of the combustion process takes place supersonically. At higher speeds, it is necessary to combust supersonically to maximize the efficiency of the combustion process."

I am not going the speed of sound.
Yet.

Yodel · Post by **Yodel** » Tue Sep 23, 2008 2:52 pm

Aumaan Anubis wrote:...well lets see. I didn't really look at it since the other guy provided a link and you didn't, but as Wikipedia says...

"A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the distinction being that some or all of the combustion process takes place supersonically. At higher speeds, it is necessary to combust supersonically to maximize the efficiency of the combustion process."

I am not going the speed of sound.
Yet.

A ground launch is unnecessary and stupid, a waste of energy. Fall off a B-52, build up some speed, SCRAMjet.

Problem solved.

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 3:03 pm

I'd like to work the kinks out of a ground launch first before, as I'm falling from the B-52, I realize, "OH CRAP I FORGOT THE FUEL!"

valdark · Post by **valdark** » Tue Sep 23, 2008 3:08 pm

Yodel wrote: Yet.

A ground launch is unnecessary and stupid, a waste of energy. Fall off a B-52, build up some speed, SCRAMjet.

Problem solved.

You are using more energy using this method.

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 3:12 pm

If I can follow common sense on this, gaining speed going toward the earth would be harder to overcome than trying to launch from rest.

For instance, I'd rather start going 5 m/s vertically when I started from 0 m/s, than going 5 m/s vertically when I started from -130 m/s.

Energy is then directed directly to going vertically, rather than slowing the effects of gravity, and then going vertically.

valdark · Post by **valdark** » Tue Sep 23, 2008 3:16 pm

Unless you are generating lift using some sort of wing jumping out of a b52 is only adding to your list of problems.

Also the expense and energy used to put the plane in the air would be a factor.

Yodel · Post by **Yodel** » Tue Sep 23, 2008 3:18 pm

You never said you wanted altitude.

You said you wanted to go. This makes you go.

Also, I was under the impression that you'd be using some sort or wing or lifting body system.

Aumaan Anubis · Post by **Aumaan Anubis** » Tue Sep 23, 2008 4:25 pm

Exactly, I don't want altitude. I want duration. I don't even want speed.

Think "jetpack."

valdark · Post by **valdark** » Tue Sep 23, 2008 4:31 pm

http://www.martinjetpack.com/video-demonstration.aspx

for 100,000 you can buy this one

guysullavin · Post by **guysullavin** » Tue Sep 23, 2008 4:36 pm

valdark wrote:http://www.martinjetpack.com/video-demonstration.aspx

for 100,000 you can buy this one

but that's loud as fuck
and i cant imagine how energy efficient that is

valdark · Post by **valdark** » Tue Sep 23, 2008 4:39 pm

30 min of flight per fueling.

guysullavin · Post by **guysullavin** » Tue Sep 23, 2008 4:48 pm

valdark wrote:30 min of flight per fueling.

oh yea, I'm ordering one RIGHT NOW

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