Save-A-Stage

dicktice · 2006-08-10 18:58:29

In order to eliminate the first booster stage structure and fuel consumption just to get a three stage rocket off the ground a few hundred feet and a hundred miles and hour straight up, an inordinate mass of fuel must be lifted that trivial height above sea level, which could just as well be accomplished, and then some, by a rocket sled up a ramp erected upon the slope of a mountain, ideally a stratovolcano located near the Equator. The scheme would save a stage by providing initial boost from ground resources, perhaps even leading to a single-stage to LEO rocket. We've debated this in the past, using maglev self-powered ramps, but by dumbing down the proposal to rocket-powered sled launches, the scheme becomes much more do-able today. Before disgarding the idea out of hand try Googling "Sky Ramp Technology" or, better yet, debating the pros and cons.

RedStreak · 2006-08-10 20:11:44

Ah yes, similiar to Arthur C. Clarke's idea for a kind of mass driver to launch objects from the lunar surface.

Its not impossible but on Earth its also more than tricky:

1) You have to compensate for atmospheric drag which could rip apart a supersonic object.

2) Digging into a mountain requires ALOT more machinery and infrastructure than any NASA launching pad. Even if its a cost-saving concept Congress is pinchy over its wallet cash.

3) If you want an equatorial launch site...not too many stable space-faring nations along the equator. Brazil is the best candidate but it is more flat than mountainous, and neither Southeast Asia or Central Africa harbor governments politically stable or with ample budgets or interest in space travel (at least at the moment).

GCNRevenger · 2006-08-10 22:22:46

And if you have a "launch incident" then all your hard work is obliterated.

Its disingenious to tell us to Google "proof" for your idea dicktice. If you have supporting information, post it, don't tell us to go out and look for it.

GCNRevenger · 2006-08-10 22:33:32

You also have a mistaken notion about orbital mechanics too I think, dicktice:

Remember, altitude is nothing, speed is everything. Asside from the few percent for atmospheric drag and <10% for gravitational losses, all that "inordinate" amount of fuel is for getting up to orbital velocity. Its all about the orbital velocity, its a race to see how quickly you can reach this speed, and this speed really determines if you are in orbit or not.

If you had a race car with an engine big enough to accelerate to orbital velocity instantly, you would enter orbit even though your starting altitude is zero and your "nose" is level with the horizon. This idea that you have to "get up high" before you are "in orbit" is almost totally false. Here:

The only reason altitude is nessesarry at all is to reduce the atmospheric drag (lower air pressure) and to reduce gravitational losses. Gravitational losses arise from the fact that you can't accelerate instantly, and for every moment of time you aren't at orbital velocity, you have to burn fuel (some time) to keep from crashing. The higher up you are, the more time you have to reach orbital velocity and less gravitation loss fuel you have to burn before crashing. A rocket sled idea like this only really affects this part, reducing the gravitational losses a little bit. The trouble is that this is already a small fraction of the total fuel needed, and a fraction of this fraction is really insignifigant.

dicktice · 2006-08-11 08:31:56

Ah yes, similiar to Arthur C. Clarke's idea for a kind of mass driver to launch objects from the lunar surface.
Reply: Well, not really, since the object is is a rocket powered stage, and not ballistic.
Its not impossible but on Earth its also more than tricky:
Reply: No more tricky than vertical launched space shuttle configuration, and the tricks have the advantage of being capable of being made fail-safe.
1) You have to compensate for atmospheric drag which could rip apart a supersonic object.
Reply: The assisted launch phase would be kept below supersonic speed at sled separation.
2) Digging into a mountain requires ALOT more machinery and infrastructure than any NASA launching pad. Even if its a cost-saving concept Congress is pinchy over its wallet cash.
Reply: The track would be constructed from prefab elements and anchored like a bridge to the mountain. The infrastructure would resemble a switching rail yard at the base, and a pleasure park ride at the top (where the sled comes to a stop and coasts back down after separation). I fail to see why the U.S. congress needs to be involved, since the facility would have a variety of launch assisted commercial single stage vehicles.
3) If you want an equatorial launch site...not too many stable space-faring nations along the equator. Brazil is the best candidate but it is more flat than mountainous, and neither Southeast Asia or Central Africa harbor governments politically stable or with ample budgets or interest in space travel (at least at the moment).

Reply: True, but as with the Panama Canal Zone, international treaties could be brokered with e.g Tanzania (for the use of Kilimanjaro) in Africa, or Ecuador (the Andes). Like Panama, the industry would provide the basis for stable government.

dicktice · 2006-08-11 08:57:22

And if you have a "launch incident" then all your hard work is obliterated.
Its disingenious to tell us to Google "proof" for your idea dicktice. If you have supporting information, post it, don't tell us to go out and look for it.

I guess you mean by launch incident, a catastrophic accident that rips apart the ramp infrastructure. Well, we could take that up as a secondary safety issue, but first I'd like to determine the viability of what these "Sky Ramp" guys are promoting "as the only way to launch a single stage rocket with a shuttle-class payload up to LEO using current end-of-the-line rocket technology."

The source I mentioned is of a promotional character, which contains all sorts of proposals, obviously commercial solutions looking for problems. Not the sort of thing to foist upon the Mars Society, except as a suggested source of ideas that need not be reinvented here (to coin a phrase).

dicktice · 2006-08-11 09:41:10

Re. "You also have a mistaken notion about orbital mechanics too I think, dicktice: "

Nope, but you will have your little school teacher session. I particularly liked your beautiful diagram, except it should've illustrated Mars, with the canon (except for the lit fuse) on Olympus Mons. It could work!

But seriously, the fact that the engine(s) use most of the fuel just to levitate the rocket, and a fraction of the thrust to accelerate upwards in a vertical launch, is what rankles. A rocket sled would "levitate" the rocket stage in its cradle without wasting onboard fuel to do so while it accelerates from the horizontal to forty-five or more degrees incline, until ignition and separation at Mach 0.9 (say) at an altitude considerably greater than it's vertically launched twin (well, not twin exactly, because of the booster, etc.) asap before heading retrograde into orbit.

We're talkin' feasibility here--to see if a practical RLV is still in the cards in time to save the space program, before the terrorists do their worst by making it all seem trivial in comparison with just plain survival on the surface of the planet.

maxie · 2006-08-11 10:40:36

Of course, on Mars such an idea looks a lot better than on Earth.

Mars has an escape velocity of 5.0 km/s (compared to Earth's 11.2 km/s). Also, the atmosphere is a lot thinner, so there is a lot less lost speed due to friction with marsian air.

And instead a rocket sled, how about a magnetic sled ? In Europe, Maglev trains can easily reach 650 km/h, for example. How about reaching 7 km/s with such a sled on Mars ? I think it will not be enough to escape orbit (Mars' gravitational acceleration will pull the vehicle back probably), but at least there will be a lot of fuel saved.

And that would de very good for a RLV, IMO.

publiusr · 2006-08-11 16:32:34

Mag-launched SSTO.
Big craft with major ground infrastructure.

HLLV
Bigger, simpler craft with mimimum pad.

Advantage, Ares V

dicktice · 2006-08-11 16:42:54

By all means: A maglev launcher, but with sled(s) switched from side tracks onto the main track at the base of the mountain, to facilitate immediate follow-on launches which have been checked out in advance. But here on Earth is where the immediate problem lies, for which I began this topic of discussion. Hope you have some thoughts.

dicktice · 2006-08-11 16:44:23

"Ares V"? Sorry, but I don't follow. I'll have to Google for it and get back to you.

EDIT: Okay, now I've got it. Boy, have I been out of touch!

[Quote] NASA announced on Friday the names of the next generation of launch vehicles that will return humans to the moon and later take them to Mars and other destinations. The crew launch vehicle will be called Ares I, and the cargo launch vehicle will be known as Ares V. [Unquote]

Shades of von Braun: It's Apollo all over again!

EDIT: Okay, again, regarding rocket sled launching up the sides of mountains. Think of it not as an alternative to Ares-V, but in addition-to. Think: Commercial, flexibility, serial launching one or more per day, public involvement, contributing to third-world country development.... But most of all, think: Private Enterprise!

SpaceBull · 2006-08-16 09:13:20

I don't think a maglev would sense from an economic point of view, and I will try to illustrate why by making up some numbers. Let's say building something like this would cost $100 billion. If the interest rate is 5% then that would be a fixed annual cost of $5000 million. If the variable cost per launch is 0, then the price per launch would be something like this:

1 launch per year - $5000 million per launch
10 launches per year - $500 million per launch
100 launches per year - $50 million per launch
1000 launches per year - $5 million per launch
10000 launches per year - $500 000 per launch

With traditional launches I guess it is the other way around, so that the fixed costs are low and the variable cost per launch is sky high. I made up all the numbers here, but the conclusion would be the same with real estimates: you need A LOT of launches per year to make a profit.

dicktice · 2006-08-16 13:44:40

Rocket assisted sled launches, possobly with linear generator braking post launch, andfor the slide back down the mountain. (Maglev is used for pleasure park rides, so why not pleasure park rides up Kilimanjaro on holidays. Just kidding, but ...?) I'm really interested in your reaction to using (to be determined) booster rockets attached to the cradle-bearing sled--returned for refuelling, naturally.

Ian Flint · 2006-08-16 23:54:12

Since equatorial countries are possibly unstable, construction and maintenance of a sled up the side of a mountain is very costly, and speed is more important than altitude...Why not build the sucker on level ground in Arizona? Cheaper, stable, and...not high...

IIRC most rocketplane designs need to be towed or refueled in midair. Just get them up to speed on the ground, fully fueled, and then whoooosh! This might solve the refueling problem or it might be worse.

What do you think?

By the way, does anybody know what happens when you go supersonic at ground level?

publiusr · 2006-08-17 10:59:29

Big simple rocket on a compact pad.

You just can't beat it.

dicktice · 2006-08-18 08:32:38

Since equatorial countries are possibly unstable, construction and maintenance of a sled up the side of a mountain is very costly, and speed is more important than altitude...Why not build the sucker on level ground in Arizona? Cheaper, stable, and...not high...
IIRC most rocketplane designs need to be towed or refueled in midair. Just get them up to speed on the ground, fully fueled, and then whoooosh! This might solve the refueling problem or it might be worse.
What do you think?
By the way, does anybody know what happens when you go supersonic at ground level?

Although it may not be applicable today, the Panama Canal construction was the similar project of the day, the Canal Zone lasting by international treaty for (was it 99 years?), and the Suez Canal also. Now they're run by the formerly unstable regimes serving to stablize them advantaging the world at large.

Starting level in Nevada or Arizona and accelerating up a mountain at 30-45 degrees a mile or so higher before relasing at just under Mach 1, could save a booster stage, and deliver payloads to the ISS.

Just under Mach 1 at height (the higher the better) means more airspeed sled release. Supersonic sleds up a mountain is probably feasible, but let's walk before we run. The main thing is to make LEO at whatever orbital plane dependable, routine and economical compared with today.

dicktice · 2006-08-18 08:41:38

Big simple rocket on a compact pad.
You just can't beat it.

True, but not for all time. Eventually, the development of the Model T Ford reliability led to roads between towns and hamlets. Reliable rocket boosters manufactured in quantity, attached to the sleds and the formerly 2nd stages etc. launched on their sides up mountain ramps will lead to launchings anywhere in the world using standardized infrastructures.

publiusr · 2006-08-22 17:44:42

But the HLLV is the Model T. Or should be.

dicktice · 2006-08-22 18:53:39

These acronyms! What's a/an HLLV, exactly?

SpaceNut · 2006-08-22 19:44:45

HLLV = Heavy Lift Launch Vehicle would cover that acronym.

oh by the way good to see that you are back...

When coming up for ideas for saving a stage it comes back to cost difference of the stage that we wish to save and what actually will replace it. There are probably many such thoughts to justify the options for this stage.

Here is a question? If a column of ocean water was removed from a launch tube with a pad that would rise from the inrushing water up the column when a vent at the bottom was opened. Would the resulting upward lift generated from the tons of water waiting to pour in lift the rocket with enough velocity to do the same efforts in saving a stage.

dicktice · 2006-08-22 20:37:11

Nice to be back.

Re. "When coming up for ideas for saving a stage it comes back to cost difference of the stage that we wish to save and what actually will replace it. There are probably many such thoughts to justify the options for this stage."

I would, at this stage in private space proposals, skip cost comparisons (with government space agencies) and just forge ahead with brainstormideas until the trends become clear. Example: If your typical 3-stage rocket stack is laid on its side, in the cradle of a sled, the 1st stage automatically becomes redundant, etc, etc.

Re. "Here is a question? If a column of ocean water was removed from a launch tube with a pad that would rise from the inrushing water up the column when a vent at the bottom was opened. Would the resulting upward lift generated from the tons of water waiting to pour in lift the rocket with enough velocity to do the same efforts in saving a stage."

This sounds a lot like what is done to launch a Polaris ICBM from a nuclear sub, so the answer is a conditional yes. All that dampness to contend with, in a private launch, could be a problem when you light the fuse!

New Mars Forums

Announcement

#1 2006-08-10 18:58:29

Re: Save-A-Stage

#2 2006-08-10 20:11:44

Re: Save-A-Stage

#3 2006-08-10 22:22:46

Re: Save-A-Stage

#4 2006-08-10 22:33:32

Re: Save-A-Stage

#5 2006-08-11 08:31:56

Re: Save-A-Stage

#6 2006-08-11 08:57:22

Re: Save-A-Stage

#7 2006-08-11 09:41:10

Re: Save-A-Stage

#8 2006-08-11 10:40:36

Re: Save-A-Stage

#9 2006-08-11 16:32:34

Re: Save-A-Stage

#10 2006-08-11 16:42:54

Re: Save-A-Stage

#11 2006-08-11 16:44:23

Re: Save-A-Stage

#12 2006-08-16 09:13:20

Re: Save-A-Stage

#13 2006-08-16 13:44:40

Re: Save-A-Stage

#14 2006-08-16 23:54:12

Re: Save-A-Stage

#15 2006-08-17 10:59:29

Re: Save-A-Stage

#16 2006-08-18 08:32:38

Re: Save-A-Stage

#17 2006-08-18 08:41:38

Re: Save-A-Stage

#18 2006-08-22 17:44:42

Re: Save-A-Stage

#19 2006-08-22 18:53:39

Re: Save-A-Stage

#20 2006-08-22 19:44:45

Re: Save-A-Stage

#21 2006-08-22 20:37:11

Re: Save-A-Stage

Board footer