2001: A Space Odyssey rocket launch

[DDE]

Point of order.

This is your movie when your science adviser is Tsiolkovsky:

I think people back (1935) then had major TWR problems with their rockets - which is ironic, seeing as how that movie also had liquid immersion used to counter launch g-forces.

 

[kerbiloid]

Why nobody advocates for the initial plan of Tsiolkovsky's multistage rocket?

A railway with a train made of sequence of rockets.
The train starts accelerating from the front rocket.

When it's out of fuel, it separates, moves forward and gets from the train way to a side way.

The second (from the front) rocket ignites and keeps pulling the train.

At last the very rear carriage (which is the ship) gets into free flight.

 

[wumpus]

On 12/4/2018 at 1:36 PM, kerbiloid said:

1. To take as much from the external power source as possible.
2. Why use subsonic+hypersonic+rocket 3-in-1 engines when can 2-in-1, without sub-.

(10 M iirc, but no matter).
Yes, and (as this has been proposed in the 1960s designs) while ascending, it should scoop and store the liquid oxygen.

The X-43 was taken to mach 10 by Pegasus and just barely managed to have a maximum thrust sufficient to maintain that speed (and technically accelerate.  Assuming the maximum thrust *was* sufficient.  The error bars were greater than the distance above "zero acceleration" for that maximum thrust (most of the time it was below that)).  The 6.8 burn was a much better example of what it could do, but I don't think it was carrying *any* payload.

Getting to mach 10 via SCRAMJET would be as big of an advancement as a reusable booster (and would cut the ultimate "high volume" ticket to space price by another 90%), but X-43 was a small step in that direction and didn't include nearly the tech needed to get there.

"scooping up liquid oxygen" assumes that you have no issues dealing with all that drag and extra liquification gear, but can't bear to bring along the oxyidizer needed to for the second (and whatever further) 6000 m/s.  I suspect that deep understanding of the rocket equation wasn't necessary for the guys doing the proposals.

On 12/4/2018 at 1:36 PM, kerbiloid said:

Imho, all stratolaunchers are a heresy^*). Any separation at the hypersonic speed would likely cause a crash, and doesn't help too much.

The point is that IRL, there exists one more or less already paid for stratolauncher: and it is still waiting for a cargo (wouldn't have been easier to get Paul Allen to fund the launcher, now things are iffy).

SSTOs belong in KSP.  They really aren't effective in worlds that require 9km/s delta-v to orbit.

On 12/5/2018 at 9:31 AM, kerbiloid said:

Why nobody advocates for the initial plan of Tsiolkovsky's multistage rocket?

A railway with a train made of sequence of rockets.
The train starts accelerating from the front rocket.

When it's out of fuel, it separates, moves forward and gets from the train way to a side way.

The second (from the front) rocket ignites and keeps pulling the train.

At last the very rear carriage (which is the ship) gets into free flight.

I don't get why he can't see that you don't push from the back (and drop off when done).  I'm pretty sure that Goddard understood that idea.

There's also a big fallacy that getting the engines in position makes sense.  At least, the engine used to put the stage in place has to be significantly more efficient than the stage used, or it doesn't give a net gain.  If your stages are all crew rated and you use Jeb's cheapest booster to put it in place (and have any failures in position before launch), than you have a net gain.

In practice, I'm absolutely convinced this is how to get a crew to Mars.  To get to Mars you need ~4000m/s delta-v beyond LEO.  At least 3000 m/s of that is all in Earth orbit (and at least within the Moon, and at least half of it is pretty close).  My suggestion would be to launch 4 roughly 1000 m/s stages (or 3 and include the first with the rocket going up) and position them with ion thrusters and fancy gravity tricks (use the Moon to go from the more or less round orbit you get from spiraling out with ions to the highly elliptical one you want to get to Mars).

Send all non-crew cargo to Mars (especially the stages needed to get home) via similar efficient means.

Ideally, the crew should travel to Mars in some sort of Aldrin cycler.  This means that the total "cost" to move each crew to Mars should be limited to hauling 4 1000m/s stages to LEO and the much smaller cost of putting them into position.  All the rest can use high-Isp/low-thrust methods as there won't be a crew on board that needs life support (including more room than a small capsule).  But it all hinges on the idea of there being a sufficiently efficient means to get *something* to Mars, even if you don't want to ride it yourself (and I think ions should be enough).

[kerbiloid]

10 hours ago, wumpus said:

X-43

Total mass = 1.4 t.  
Payload = 1 Kerbal.

And I mean 10-40 t payloads.
You can't make such big carrier plane.

Say, the biggest reasonable plane is 1000 t in total.
Say, its cargo = 400 t.

This means that a plane carrier will never deliver to orbit more that ~8 t of payload.
And to deliver 8 t a complicated double-spaceplane thing doesn't make sense.

10 hours ago, wumpus said:

IRL, there exists one more or less already paid for stratolauncher

With ~0.5 t or so payload.

P.S.
(Just in case. I mentioned the Tsiolkovsky's project just as a joke. I don't advocate for the pulling rocket train.)

[DDE]

On 12/5/2018 at 5:31 PM, kerbiloid said:

Why nobody advocates for the initial plan of Tsiolkovsky's multistage rocket?

A railway with a train made of sequence of rockets.
The train starts accelerating from the front rocket.

When it's out of fuel, it separates, moves forward and gets from the train way to a side way.

The second (from the front) rocket ignites and keeps pulling the train.

At last the very rear carriage (which is the ship) gets into free flight.

 

Where’s @kerbiloid and what have you done with him?

[kerbiloid]

1 hour ago, DDE said:

Where’s @kerbiloid and what have you done with him?

Who summons me to the world of non-darkness???

And how does TKS relate to a multistage rocket train?

[wumpus]

On 12/7/2018 at 5:17 AM, kerbiloid said:

With ~0.5 t or so payload.

P.S.
(Just in case. I mentioned the Tsiolkovsky's project just as a joke. I don't advocate for the pulling rocket train.)

Stratolaunch was supposed to be ~6.1 tons (to LEO).  .5t is a Pegasus that can be launched with a B-52 or L-1011.  Basically the Dragon, or similar sized satellites (and good luck scaling it up).  On the other hand you are likely to have the same issues scaling up any rocket launched from some sort of ground-based launcher.

I'm not at all surprised that Stratolaunch can't find a serious builder for a rocket (multiple pegasus launches at once are a joke), and even less surprised that nobody has attempted to build a rail-based launcher.

[kerbiloid]

8 minutes ago, wumpus said:

Stratolaunch was supposed to be ~6.1 tons (to LEO). 

I.e. a 1 Soyuz payload or 1/5 of Shuttle.