[AR] Re: Way OT question: degerate matter thrusters?
- From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Wed, 18 Feb 2015 16:18:55 -0500
What Nathan said, except that tank propellant fractions of 96% are
achievable--with solid propellant--which is a mass ratio of 25, not 6...but
still rather a long way from eight million....
Bill
Sent from my iPhone
On Feb 18, 2015, at 3:54 PM, "Galejs, Robert - 1007 - MITLL"
<galejs@xxxxxxxxxx> wrote:
> Maybe I can ask my question once again, very precisely…
>
> Is it theoretically possible, assuming I give you a magical tank with zero
> weight and arbitrarily high tensile strength, to put an object into orbit
> using highly compressed air (think giga-atmospheres of pressure or more)? Or
> is there some physics limitation (like the tank freezing from the air
> expanding or some other thermodynamic gotcha) that would make this
> theoretical rocket not work?
>
> - Robert
>
> From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
> Behalf Of rsteinke@xxxxxxxxxxx
> Sent: Wednesday, February 18, 2015 3:40 PM
> To: arocket@xxxxxxxxxxxxx
> Subject: [AR] Re: Way OT question: degerate matter thrusters?
>
> The engineering issue of tank weight is what would keep it from getting to
> orbit. Compressed air rockets work fine except that you just can't get very
> good mass ratio from a tank of air. Going to higher pressures doesn't help
> because the tank has to get heavier to hold the higher pressure. The reason
> that liquid fuels are better is that they are higher density than air at the
> pressures that generally make sense inside rocket propellant tanks.
>
>
> ----- Original Message -----
> From:
> "Galejs, Robert - 1007 - MITLL" <galejs@xxxxxxxxxx>
>
> To:
> "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
> Cc:
>
> Sent:
> Wed, 18 Feb 2015 20:30:15 +0000
> Subject:
> [AR] Re: Way OT question: degerate matter thrusters?
>
>
> I believe that that's a bad example. If I understand things properly, I
> believe that the ISP of the air alone is higher, but the mass flow with water
> is much better.
>
> But you missed my point entirely... I wasn't trying to optimize anything, I
> was just trying to see if using hyper-compressed air at some arbitrarily high
> pressure could be used to get something into orbit theoretically, ignoring
> obvious engineering issues like tank weight.
>
> - Robert
>
> -----Original Message-----
> From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
> Behalf Of Monroe L. King Jr.
> Sent: Wednesday, February 18, 2015 3:20 PM
> To: arocket@xxxxxxxxxxxxx
> Subject: [AR] Re: Way OT question: degerate matter thrusters?
>
> Here's a simple experiment to show you. Go down to the toy store and buy
> yourself one of the old pump up water rockets. Pump it up with air and let
> her
> rip. Then fill it with water and try again at the same pressure.
>
> Monroe
>
> > -------- Original Message --------
> > Subject: [AR] Re: Way OT question: degerate matter thrusters?
> > From: "Galejs, Robert - 1007 - MITLL" <galejs@xxxxxxxxxx>
> > Date: Wed, February 18, 2015 1:10 pm
> > To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
> >
> >
> > So why is supercritical steam "better" than air?
> >
> > -----Original Message-----
> > From: arocket-bounce@xxxxxxxxxxxxx
> > [mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of Monroe L. King Jr.
> > Sent: Wednesday, February 18, 2015 3:01 PM
> > To: arocket@xxxxxxxxxxxxx
> > Subject: [AR] Re: Way OT question: degerate matter thrusters?
> >
> > Well so does HP air. Unless your using just a plain ol jet engine like
> > a ramjet. That would be HP air also.
> >
> > > -------- Original Message --------
> > > Subject: [AR] Re: Way OT question: degerate matter thrusters?
> > > From: "Galejs, Robert - 1007 - MITLL" <galejs@xxxxxxxxxx>
> > > Date: Wed, February 18, 2015 12:55 pm
> > > To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
> > >
> > >
> > > Supercritical steam does not require heavy tankage?
> > >
> > > -----Original Message-----
> > > From: arocket-bounce@xxxxxxxxxxxxx
> > > [mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of Monroe L. King Jr.
> > > Sent: Wednesday, February 18, 2015 2:47 PM
> > > To: arocket@xxxxxxxxxxxxx
> > > Subject: [AR] Re: Way OT question: degerate matter thrusters?
> > >
> > > I think Supercritical steam would be better than air. High
> > > pressures require heavy tankage.
> > >
> > > Monroe
> > >
> > > > -------- Original Message --------
> > > > Subject: [AR] Way OT question: degerate matter thrusters?
> > > > From: "Galejs, Robert - 1007 - MITLL" <galejs@xxxxxxxxxx>
> > > > Date: Wed, February 18, 2015 12:35 pm
> > > > To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
> > > >
> > > >
> > > > I know this is way off-topic, but it has always had me wondering
> > > > and it seems like Arocket has the appropriate knowledge base to
> > > > address this (or, at least wildly speculate).
> > > >
> > > >
> > > >
> > > > In some of Larry Niven's sci-fi stories, he imagines rocket
> > > > thrusters (between the ground and orbit) based on super-compressed
> > > > air (supposedly "nearly degenerate matter"). Would such thrusters
> > > > theoretically work, or are there some thermodynamic (or other
> > > > physics) limitations that come into play?
> > > >
> > > >
> > > >
> > > > Thanks,
> > > >
> > > >
> > > >
> > > > Robert
>
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