# Aerospace Rocket engines

1. Sep 22, 2003

### meteor

Hello, I'm interested in knowing which is the rocket engine of all that have been constructed to date that has major thrust
The first in my list is the RD-170, that was used in the Energia launch vehicle, and is still used in the Zenith rocket. The RD-170 rocket engine has a nominal thrust of 7904490 N.
In second position I have the F-1 rocket engine, used in the Saturn V.
The F-1 has a nominal thrust of 6770193 N.
There has been constructed other rocket engine with greater thrust?

2. Sep 25, 2003

### drag

Thrust sucks ! Specific Impulse (Isp) rocks !

I think you got'em right meteor, not 100% sure though.

3. Sep 25, 2003

### meteor

drag,
the specific impulse of the RD-170 is about 310 s. Compare with the VASIMR that can achieve 30000 s. of Isp!
Other thing, the RD-170 uses like propellant liquid oxigen as oxidizer and kerosene as fuel. Do you think that there is another propellant that could provide more thrust to the RD-170?

4. Sep 26, 2003

### wimms

why is kerosene better than hydrogen, apart from safety and cost?

5. Sep 26, 2003

### drag

Greetings !
Exactly, but more to the point - if we're talking
about rockets - the RL-10 is a winner with an Isp
around 450 for the various types. Of course, it's a
much smaller engine so it's been used so far as
a third stage, but it can be used as a first or second
stage for smaller launch vehicles - and then its high Isp
would really win the day in terms of the propellant mass,
the engine mass, reusability - it can be restarted about
10 times and then overhauled and as a consequence - the
overall costs. (If I remember correctly it uses LOX or LOH2.)

Live long and prosper.

Last edited: Sep 26, 2003
6. Sep 27, 2003

### ATCG

Anti-matter propulsion

Forget Nuclear, anti-matter is the coming future for rocket propulsion. In fact, I have the schematics for a hybrid anti-matter rocket. Unfortunatly anit-matter is the most expensive substance in the world and it is predicted that the rocket would let off immense gamma radiation thousands of miles long. Another drawback is the weight. The current design for this type of rocket weighs about 400 tons. On the plus side, the rocket could fly to mars on one-billionth of a gram of anti-matter in a few weeks instead of months. This is attainable because antimatter/matter annihilation produces the highest known physical reaction in the world. The rocket technology will really revolutionize space travel and will possibly make travel to other regions of deep space possible.

-ATCG

7. Sep 27, 2003

### enigma

Staff Emeritus
Re: Anti-matter propulsion

Has a technological readiness level of 1 or 2, whereas nuclear has working examples in related systems, placing its TRL between 3 and 5.

Yes, it may be better long term, but it's nowhere near a working prototype.

Oh, and the cost of fuel is a big deal. If you can get to Mars in 2 weeks at a cost of $1 Trillion+ or in 6 weeks at a cost of$100 Billion+, which is the better alternative?

8. Sep 27, 2003

### drag

Re: Re: Anti-matter propulsion

Greetings !

Well, ATCG you're right in a very general sense -
anti-matter is one of the most likely things to really
get us going in space at sub-light velocities. But it's not
going to happen in the near future. Perhaps, in several
decades we will find ways to produce sufficient amounts
of it at reasonable costs. Once that is achieved, of course,
the remaining problems of storing it and using it's power in
space are rather "small" by comparisson. Of course, by then
it's possible that we'll be using small and effective
fusion reactors, which while not as efficient will cost
less and will have the afvantage of being located on the
spacecraft itself thus evoiding the risk of storing
and handling anti-matter during the entire mission.

Looking beyond that into interstellar travel(if we locate
some habitable planets in nearby systems to go to) - that,
indeed, will only be possible using anti-matter for
any manned mission (unless physics surprises us with
some new FTL stuff).

(edited for typos)

Live long and prosper.

Last edited: Sep 27, 2003
9. Sep 27, 2003

### drag

BTW, actually you'll need at least a few tens of gramms
of the stuff for a manned two-way Mars mission.

Peace and long life.

10. Sep 30, 2003

### Tyro

I don't see how antimatter-matter can be the way to go. Antimatter is not something you can go out and mine locally, and to synthesize it you need an energy source. You will need to provide more energy than the energetic value of the antimatter - after you factor in conversion efficiencies. You are probably talking nuclear power to generate usable quantities of antimatter. Which begs the question - why not just use nuclear propulsion instead of nuclear -> antimatter propulsion?

Antimatter is great for bombs, though. Nothing like an antimatter hand grenade with a yield in the MT range to make your enemies' day.

11. Sep 30, 2003

### Tyro

Kerosene is a liquid fuel, easy to handle and pump around. Hydrogen is a gaseous fuel that needs specially treated or lined pipes/tanks to pump it around. Hydrogen can damage and indeed, destroy untreated materials when in proximity to it. Known as Hydrogen Embrittlement Cracking (HEC), it causes reduced fracture toughness. Unfortunately, materials particularly prone to HEC are high-strength steel, titanium and aluminium alloys - all very popular in the aerospace industry .

Plus there is also the problem that to store hydrogen in its molecular form, you either have to cryogenically store it or compress it, or both. Cryogenic storage has the problem of reducing the energy content of the fuel because you need to supply the latent heat of vapourisation to the liquid form and any specific heat to warm it up. Compressing it requires reinforced tanks which are heavy. There is some progress in composite construction tanks, e.g. carbon fibre tanks but they are all susceptible to damage. Last thing you want is a fuel tank breach

That all said, although hydrogen has one of the highest gravimetric energy densities, it has one of the lowest volumetric ones - meaning that while it is a light, powerful fuel, it will also probably involve bulky tanks.

12. Sep 30, 2003

### LURCH

True, but at the risk of going slightly off-topic, I read at space.com that one particular Solar flare produced a pound of antimatter.

13. Oct 1, 2003

### Tyro

Haha...my sentiments exactly.

14. Oct 3, 2003

### drag

Greetings !
You misunderstood. The idea is to produce the anti-matter
on Earth, store it in magnetic containment and then use these
stores to produce energy to power your propulsion system.

Live long and prosper.

15. Jan 3, 2004

### Lord Flasheart

Sorry, I just couldn't resist this first topic I would post on. Tyro, it's not a matter of enough energy, it's the matter of energy density. All the potential of a particle accelerator or a nuclear reactor, (Sol, for example) which would be operating for a long period of time, would be packed into those few (kilo-)grams of antimatter. This is why antimatter drive is actually a stupendous propulsion system. It would only require some couple hundred tons of ice for a trip to another world, (the ice being used for propulsion and life support as well as cooling) and only a kilogram or so of antimatter. With conventional rocket engines, or even a NERVA type rocket, you would need so much more fuel, and because of the slower specific impulse, the ship would need much more life-support tonnage to accomadate the crew.

Just my two hundreths of a dollar.