Non-RO launch vehicles for RSS

[Laie]

@AllenLi making the turn too shallow, and then keeping the rocket pitched up later, is a trick I learned playing RO. Picking up extra horizontal velocity early on is so valuable that it more than makes up for the cosine losses of the pitch.

Hold on, let's see if I can do this without youtube...

(edit) yup, it works. Full ascent as time-lapse video, 37 seconds, 7MB.

This time it's 5x Wolfhound, 4x Rhino, and -again- twelve SRBs.

• 619,353 funds
• 2805 tons

Compared to my previous stack, that's a 10% reduction in mass for a similar payload. Some of the work has been moved from the upper to the sustainer. Improved ISP overall means less propellant carried, resulting in comparable TWR at liftoff.

3 hours ago, AllenLi said:

If all that [...] isn't enough, we may need KSPIE,

Sorry, this isn't relevant to the challenge, but I have to ask: are you aware of SMURFF? It's totally possible to have reasonable mass fractions without getting the whole RO suite.

Edited May 24, 2020 by Laie

[Pds314]

Hmmm. Yes the mountains behind Xichang launch complex are maybe TOO tall....

Uhhh... hmmm.... Isn't Everest like 8950 or something?

Edited May 26, 2020 by Pds314

[Pds314]

When you're minding your own business at 46000 feet when suddenly *TERRAIN! TERRAIN! PULL UP!*


14138 meter mountain!

Is the mean altitude of Tibet in the stratosphere in RSS???

Edited May 26, 2020 by Pds314

[Pds314]

Alright. This is Everest.... yeah... I don't even... Why is it slightly over twice as tall as real life?

[Pds314]

Hmm... Launching from Vandenberg and heading north to the pacific Northwest of the US, I looked at two mountains near where I live. Mt. Rainier and Mt. Hood.

Mt. Rainier is ridiculously tall. Over 11 km. IRL value is 4.4.


But Mt. Hood is much smaller. About 4.9 km. But IRL it's 3.4.


I think something really wierd is going on with the terrain scaling. Low altitude terrain seems to be at normal altitudes, ish. But higher up terrain is much higher than it should be.

Edited May 26, 2020 by Pds314

[Laie]

55 minutes ago, Pds314 said:

I think something really wierd is going on with the terrain scaling. Low altitude terrain seems to be at normal altitudes, ish. But higher up terrain is much higher than it should be.

The terrain map, specifying altitude at a specific ground position, is incredibly coarse-grained. Hold on.... on my install, it's 8196px wide and 4096 tall. So on the equator, one data point determines an area of approx 5x5km. The specific terrain is made up by an algorithm. In first approximation, higher ground is more bumpy (=mountains) while lower ground is less so (gentle dunes).

I think the bumpiness can be overridden in some way, perhaps taking the biome map as a hint? You'd have to ask the folks at Kopernicus for details. But I don't think it's possible to have Mount Everest in just the right position. At best, you can make it so that the Himalayas, Andes or Alps have about the right altitude, on average.

 

[Pds314]

12 minutes ago, Laie said:

The terrain map, specifying altitude at a specific ground position, is incredibly coarse-grained. Hold on.... on my install, it's 8196px wide and 4096 tall. So on the equator, one data point determines an area of approx 5x5km. The specific terrain is made up by an algorithm. In first approximation, higher ground is more bumpy (=mountains) while lower ground is less so (gentle dunes).

I think the bumpiness can be overridden in some way, perhaps taking the biome map as a hint? You'd have to ask the folks at Kopernicus for details. But I don't think it's possible to have Mount Everest in just the right position. At best, you can make it so that the Himalayas, Andes or Alps have about the right altitude, on average.

 

Everest IS in the right position. Horizontally anyway it's essentially perfect. Vertically though, not just Everest but essentially the entire Tibetan plateau is several kilometers too high. And the average altitude of the Himilayas is probably over 10 km.

Edited May 26, 2020 by Pds314

[CFYL]

Spoiler

On 5/25/2020 at 1:46 AM, Laie said:

@AllenLi making the turn too shallow, and then keeping the rocket pitched up later, is a trick I learned playing RO. Picking up extra horizontal velocity early on is so valuable that it more than makes up for the cosine losses of the pitch.

Hold on, let's see if I can do this without youtube...

(edit) yup, it works. Full ascent as time-lapse video, 37 seconds, 7MB.

This time it's 5x Wolfhound, 4x Rhino, and -again- twelve SRBs.

• 619,353 funds
• 2805 tons

Compared to my previous stack, that's a 10% reduction in mass for a similar payload. Some of the work has been moved from the upper to the sustainer. Improved ISP overall means less propellant carried, resulting in comparable TWR at liftoff.

Sorry, this isn't relevant to the challenge, but I have to ask: are you aware of SMURFF? It's totally possible to have reasonable mass fractions without getting the whole RO suite.

I’m putting you up. I have to say that, although I can view your videos thumbnail, I can’t see its contents if I press the play button. Sorry for that.

Spoiler

On 5/26/2020 at 10:07 PM, Pds314 said:

Everest IS in the right position. Horizontally anyway it's essentially perfect. Vertically though, not just Everest but essentially the entire Tibetan plateau is several kilometers too high. And the average altitude of the Himilayas is probably over 10 km.

Xichang is nowhere near the Everest though it’s on the edge of the Tibetan Plateau. This height problem isn’t quite new to us RSS people but…… I’m not sure if it was because RSS heights counted the “lump” on the equator caused be the earth’s rotation. We all know that the radius expands from about 6360 to 6390 from the poles to the equator, covering an average 6371. This is true on Vesta where I have been, but not quite sure for the earth. If this was true on the earth, I wonder if the moon was made into an egg shape by the earth’s tidal force in RSS…

If you want shuttles, Changcheng-1 was promoted by the PRC in the 20th century and was the original vessel in an official craft replica, which I forgot the name. Some changes can bring it to LEO. More recently, around May the fifth, as a far as I know from some of our aerospace tracking websites, CASC launched a “secret” payload on a CZ-2F to LEO, and it was presumed to be a new spaceplane. It’s nature determines that it isn’t known to us because CASC want’s to keep it secret. Launched form Jiuquan.

That was not relevant to this challenge, so you may consider keeping it low here but I’d  be glad to discuss it with you elsewhere on some specific threads.

[Laie]

On 5/28/2020 at 4:30 PM, AllenLi said:

I’m putting you up. I have to say that, although I can view your videos thumbnail, I can’t see its contents if I press the play button. Sorry for that.

Hmm. It's just a hyperlink leading to a .webm file, which I thought would play inline in every browser. Can you download the file ("save link as") and view it in another application, perhaps.

Meanwhile, I've had a look at Near Future Propulsion...

• First off, the engines have tremendous power requirements on the order of 400-3000 units of ElectricCharge per second. You definitely want "Near Future Electrical" for the nuclear reactors to drive them.
• Don't bother with "Near Future Solar": Solar Panels are much heavier than reactors, even after factoring in the heatsinks.
  Solar power becomes interesting only if you need power for years, where a reactor's fuel supply would need to be replaced.
• Reactors create a lot of CoreHeat, requiring radiators. Far and away the best heat sinks / mass are the stock static panels. Nertea's "Heat Control" mod offers some good-looking items, but they are heavier and require more power than stock panels.
• NFE also brings "capacitors" which store 8x as much electricity per mass compared to batteries.
  • Technically speaking, they hold a resource called "StoredCharge" that converts 1:1 to/from ElectricCharge.
  • Capacitors charge only slowly, can hold their charge for ever, and can be discharged at the press of a button.
  • Discharging a capacitor will dump it's entire StoredCharge in a matter of 10-20 seconds. Once started, the discharge cannot be stopped.
  • If your consumption is less than the discharge rate, you need a large enough conventional battery to act as buffer, or the charge will be wasted.
  • for all that, they're still rather heavy. If you need power for more than approx. 5 minutes, it's better to bring an adequately-sized power supply.

For the purposes of our challenge, only to kinds of engine are of interest:

1. the most powerful Ion engine: 3.8kN, 19200 ISP, 400EC/s.
   There's many other engines with a slightly better TWR and much worse ISP. All of them will require burn times upwards of one hour. In convenience terms, I think that once you're willing to take that time, you may as well go all the way and pick the single most efficient engine. Including power supply and radiators, the engine package comes to 1.5t and requires virtually no propellant.
2. Magnetoplasmadynamic Engines.
   Including the power supply and radiators, these provide NERV-like TWRs on the order of 24-30kN / ton, however at ISPs of 2600-3500, with the biggest Item having the worst TWR and best ISP. That's totally suitable for an upper stage and can provide about half the dV to LEO in the first place.
   They create a lot of heat and need active cooling, though. As radiators will only shed normal (non-"Core") heat outside of the atmosphere, you absolutely have to be above 140km within 30-50 seconds after ignition.

With an electrical upper stage, I manage a liftoff mass under 500t. Discarding a reactor after 15 minutes of use isn't exactly economical, though.

[moar ssto]

Just landed my stock part ssto on Titan.