Car powered by compressed air?

Isn't the effective exhaust velocity directly proportional to Isp?

I learned about that from the audio recording of a series of lectures given for a course at MIT by Shuttle engineers - they also have them on video here:

Unfortunately I can't now recall the specific lecture, probably the one on propulsion.

Wikipedia

sez:

"Liquid fueled engines are often run fuel rich, which results in lower temperature combustion. Cooler exhaust reduces heat loads on the engine allowing lower cost materials, a simplified cooling system, and a lower performance engine."

In the lecture (circa 2005) this engineer stated that they pretty much ran the engines at the maximum temperature the state of the art in the mid 1970s would allow, and that in many respects the SSMEs are still state of the art when it comes to liquid bi propellant engines.

Because the effective exhaust velocity for hydrocarbons is lower. The energy density of gasoline is higher than hydrogen, but in a rocket the slower exhaust velocity causes decreased performance.

E = 1/2 MV^2, M matters too.

RP-1 is essentially kerosene, AlwaysWrong. Guess what "RP" means, DimBulb?

e:

er

r

ulb?

Name one manned booster (US) that used a petroleum propellant?

You say that like it's a *bad* thing.

Previous posts have completely missed the two monumentally stupid reasons nobody, but nobody EVER would use liquid hydrogen for automotive apps.

First and foremost, ALL of the energy (and then some) in liquid hydrogen comes from oil, gas, or coal. Especially that energy used in the methane reformation and in the electricity used for compression.

Naturally, renewable electricity is utterly and totally totally useless for electrolysis because of the staggering loss of exergy; there ALWAYS will be more intelligent things to do with a renewable electricity source.

Meanwhile, most thermodynamically efrficient processes have to approach reversibility, and one good way to do this is to get and stay as isothermal as possible. Having a super cold phase flies in the face of all that remains sane of thermodynamics.

--
Many thanks,

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100 percent of ALL the X Prize candidates.

Any more stupid questions?

-- Many thanks,

Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss:

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Please visit my GURU's LAIR web site at

You're asking "Always wrong" for a non-stupid question? That's a hoot.

tm

'Ortho' needs to improve their anti-troll spray.

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.

Aren't some big diesels started with compressed air?

John

ean

d for

to

u

omprim=E9

ever.

know big ship engines are, also seen it used on cars used in a coal mine

-Lasse

The big rigs already have compressed air and the storage tank for it used for braking. They don't try to replenish the air supply by "regenerative braking", as electric vehicles replenish battery charge. This sort of thing is needed if the idea is to improve energy use in the "start-stop" situation.

--
Virg Wall

No I am not. At worst you are like a poison ivy itch, slightly annoying but of no consequence.

You implied a few things, a tactic that is usual for you in your " game".

Now that I answered two of your que stons, how about answering some of mine I asked you?

Not a chance, I know, but then I know how much of a coward you really are.

Moe

But Ortho makes birth contr.... oh, I see.

He is a moron, which isn't good. He's here, which is very bad.

Atlas was fueled by RP-1 and LOX. You must try to be an idiot. No one can be that stupid accidentally.

I've noticed that myself. If he were merely stupid, you'd expect him to be right once in a while, by accident. But he's AlwaysWrong.

John

You're a retard, who's entire bloodline should be erased from the gene pool.