Get a full orange tank to orbit using only mono prop and xenon

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Rules:

1. No Dirty Cheating Alpacas (no debug menu)!

2. No mods

3. no kerbals required

4 post screenshot of craft on launch pad, and one for each stage and in orbit right click on tank to show it is full

5 Impress me E.g post videos

post screenshots below

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Seems tough. But interesting. I'm assuming "Puff" will be the name of the game.

How'd you manage it?

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I'd like to know how one manages this. Just making the attempt, I stopped after building a 1300 part 250 tonne asparagus-staged monstrosity that only made an apoapsis of 41 km. I've never experienced slideshow-like performance on my Core i7 PC before today.

With tank priorities in 1.2.1, it's possible to asparagus-stage monopropellant rockets. The same rocket not asparagus-staged made it to 22 km barely.

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Sound to me it is near impossible... Could the OP post his successful attempt?

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Could it be done using an SSTO Monoprop/Xenon plane? That seems like it might be more efficient. Further testing is required...

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By the sound of it, this is pretty much impossible. Now, my math might be off - so someone can feel free to correct me if I'm wrong

Calculating how many large mono propellant tanks we'd need:

Spoiler

The formula for delta-v is:

```
Delta_V = 9.81 * Isp * ln(start_mass / final_mass)```

Other facts:

• We need about 3400 to reach orbit.
• The only feasible engine is the Puff, which has an Isp of 120 (atmo) / 250 (vaccuum) - just to play on the safe side, we'll call it 220 (which is the average of the Isp's needed in the first 10k meters based on atmosphere pressure...if anyone wants me to expand on how I found this, I will).
• And since it's the same engine for all stages, we can just use a single value of 220 for the Isp
• The most efficient container of mono-propellant (mostly ignoring how tall this thing is going to be) is the largest tank, which is 3.4 tons when full, and 0.4 when empty.
• The 36 ton orange container is a static weight that will be factored in for the entire trip

Thus, our revised formula is:

```
start_mass = 36 + (3.4 * number_of_tanks)
final_mass = 36 + (0.4 * number_of_tanks)

3400 = 9.81 * 220 * ln(start_mass / final_mass)```

Solving for the "number_of_tanks" variable, it comes out to be 94.055 or 94 tanks

Calculating how many Puff engines we'd need:

Spoiler

Okay, but then how many Puff engines do we need? Well, we'll need a TWR above 1, ideally about 1.5.

The formula for TWR is:

```
TWR = total_engine_thrust / (mass * gravitational_acceleration)```

More related facts that we now know:

• The ideal TWR is 1.5
• The total engine thrust will be 9.6kN (the atmo thrust for the Puff engine)
• The mass will be the starting mass, as given before
• The gravitational acceleration from sea level Kerbin is 9.81

Thus:

```
1.5 = (9.6 * num_engines) / ((36 + 3.4*94) * 9.81)```

Solving for the "num_engines" variable, it comes out to be 545.068 or 545 Puff engines....

So based on my math, you'd need 94 tanks of mono propellant and 545 Puff engines. And that's of course assuming you're building a SSTO - which, you'd kinda need to do as adding on any extra weight (by making an asparagus or onion rocket) would cause you to drastically increase the number of engines you'd need.

I also realize that my math might be off. And I also realize that I shouldn't undermine the community's level of creativity. But by the sound of it....this is a pointless challenge....

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5 hours ago, shirtandtieler said:

By the sound of it, this is pretty much impossible. Now, my math might be off - so someone can feel free to correct me if I'm wrong

Calculating how many large mono propellant tanks we'd need:

Hide contents

The formula for delta-v is:

```

Delta_V = 9.81 * Isp * ln(start_mass / final_mass)```

Other facts:

• We need about 3400 to reach orbit.
• The only feasible engine is the Puff, which has an Isp of 120 (atmo) / 250 (vaccuum) - just to play on the safe side, we'll call it 220 (which is the average of the Isp's needed in the first 10k meters based on atmosphere pressure...if anyone wants me to expand on how I found this, I will).
• And since it's the same engine for all stages, we can just use a single value of 220 for the Isp
• The most efficient container of mono-propellant (mostly ignoring how tall this thing is going to be) is the largest tank, which is 3.4 tons when full, and 0.4 when empty.
• The 36 ton orange container is a static weight that will be factored in for the entire trip

Thus, our revised formula is:

```

start_mass = 36 + (3.4 * number_of_tanks)
final_mass = 36 + (0.4 * number_of_tanks)

3400 = 9.81 * 220 * ln(start_mass / final_mass)```

Solving for the "number_of_tanks" variable, it comes out to be 94.055 or 94 tanks

Calculating how many Puff engines we'd need:

Hide contents

Okay, but then how many Puff engines do we need? Well, we'll need a TWR above 1, ideally about 1.5.

The formula for TWR is:

```

TWR = total_engine_thrust / (mass * gravitational_acceleration)```

More related facts that we now know:

• The ideal TWR is 1.5
• The total engine thrust will be 9.6kN (the atmo thrust for the Puff engine)
• The mass will be the starting mass, as given before
• The gravitational acceleration from sea level Kerbin is 9.81

Thus:

```

1.5 = (9.6 * num_engines) / ((36 + 3.4*94) * 9.81)```

Solving for the "num_engines" variable, it comes out to be 545.068 or 545 Puff engines....

So based on my math, you'd need 94 tanks of mono propellant and 545 Puff engines. And that's of course assuming you're building a SSTO - which, you'd kinda need to do as adding on any extra weight (by making an asparagus or onion rocket) would cause you to drastically increase the number of engines you'd need.

I also realize that my math might be off. And I also realize that I shouldn't undermine the community's level of creativity. But by the sound of it....this is a pointless challenge....

Seems reasonably good approximation for an SSTO.

But what you seem to be missing is that you could obviously do it more efficiently by asparagus staging.

Just drop empty tanks every once in a while and you will increase your dv signnificantly (you can also drop some engines once you get higher since your craft becomes lighter and your engines gain more thrust...) which means you need less tanks to start with which means you'll need less engines to start with. But all in all I agree that the numbers you need will still be ridiculously high...

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8 hours ago, tseitsei89 said:

Seems reasonably good approximation for an SSTO.

But what you seem to be missing is that you could obviously do it more efficiently by asparagus staging.

Just drop empty tanks every once in a while and you will increase your dv signnificantly (you can also drop some engines once you get higher since your craft becomes lighter and your engines gain more thrust...) which means you need less tanks to start with which means you'll need less engines to start with. But all in all I agree that the numbers you need will still be ridiculously high...

Thanks! Though I did say at the end that I realize my math was assuming you were building an SSTO

Also, I did sort of attempt your idea. Asparagus staging isn't "technically" possible, since mono-prop doesn't need fuel lines, but I did do something kinda similar.

Mind you, I whipped this monstrosity up in 20 minutes....though, 15 of those minutes were trying to rearrange parts and deal with the intense lag.

And speaking of the lag, I was getting about 3 FPS when flying this...and only got to 3,865m

So if I gave myself more time, I might be able to complete this challenge. But seeing that there's not much part freedom (at least practically) and that it kills my FPS so much, I don't find it worth trying. But I am kind of interested in seeing OPs creation....

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And now I'm seeing the math come out. Why do I have a bad feeling the OP is nerd-sniping us?

--

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8 hours ago, Gordon Fecyk said:

And now I'm seeing the math come out. Why do I have a bad feeling the OP is nerd-sniping us?

--

At this point, I'm pretty sure he is. Though, you only saw the math come out before I'm not a skilled enough designer to think of some ingenious creation that would make this work....and also because my patience ran out when my FPS dropped to 3 lol.

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I'll see your three FPS and raise you about one frame every five seconds, or 0.2 FPS.  That was the result I got when I finally managed to get the thing into space, but not into orbit.

The craft was a stupid 2800+ parts and consisted of 8 x 9 x 12 O2 engine + small RCS tank + decoupler combos, and two orange tanks (one empty) for structure. Nine asparagus-like stages using tank priority. Managed to record and compress a video to 4x playback speed:

I don't suppose the "Stress The Devs" contest is still open for entries?

And that's enough. I'm not coming back to this until mlg-dank-meme-lord posts a successful attempt.

Edited by Gordon Fecyk
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Random thought that I'm not going to bother trying because this challenge asks me to use 2 things I hate: pure stock and the puff engine

Could you, in the spirit of the challenge, launch an empty orange tank and then launch 2 half tanks to fill it up? Or 4 quarter tanks? The OP does not state only 1 launch, and "craft" is its own plural.

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You'd have a better chance using that Orion drive someone made out of landing legs and monoprop tanks.

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But can we use wings, though? In theory you could fly a multi-stage to orbit with a TW ratio of about .5, with only the last couple stages boosting it above one to get into orbit. I tried this and was able to clear 70,000m but was short 500m/s to orbit.

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On 23-11-2016 at 3:28 AM, Gordon Fecyk said:

I'll see your three FPS and raise you about one frame every five seconds, or 0.2 FPS.  That was the result I got when I finally managed to get the thing into space, but not into orbit.

The craft was a stupid 2800+ parts and consisted of 8 x 9 x 12 O2 engine + small RCS tank + decoupler combos, and two orange tanks (one empty) for structure. Nine asparagus-like stages using tank priority. Managed to record and compress a video to 4x playback speed:

[VidSnip]

I don't suppose the "Stress The Devs" contest is still open for entries?

And that's enough. I'm not coming back to this until mlg-dank-meme-lord posts a successful attempt.

You might be able to safe some weight by only staging the empty tanks and keeping the engines. The saved weight can then be used to carry extra fuel.

But you are right. Unless @Mlg Dank Meme lord posts a serious attempt (it doesn't even have to be successful) I would not bother either.

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5 hours ago, NightshineRecorralis said:

But can we use wings, though? In theory you could fly a multi-stage to orbit with a TW ratio of about .5, with only the last couple stages boosting it above one to get into orbit. I tried this and was able to clear 70,000m but was short 500m/s to orbit.

Wait, can you post images or the craft file? I might be wrong but I thought the TWR ratio was relative to the surface gravity and thus you need it to be greater than 1 just to lift off - i.e. a TWR of 1 means the thrust is equal to the gravity, and anything at 1 or below == no liftoff.

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4 hours ago, shirtandtieler said:

Wait, can you post images or the craft file? I might be wrong but I thought the TWR ratio was relative to the surface gravity and thus you need it to be greater than 1 just to lift off - i.e. a TWR of 1 means the thrust is equal to the gravity, and anything at 1 or below == no liftoff.

True for rockets but if you add wings you generate lift and can fly with a twr much lower than 1 obviously.

Or did you honestly think that all aeroplanes in real life have a twr greater than 1?

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On 11/24/2016 at 8:17 PM, tseitsei89 said:

True for rockets but if you add wings you generate lift and can fly with a twr much lower than 1 obviously.

Or did you honestly think that all aeroplanes in real life have a twr greater than 1?

Had a bit of a derp moment there, as I was thinking strictly of rockets where you are just flying straight up. I guess that does make this "challenge" mildly more possible haha.

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On 2016-11-22 at 9:28 PM, Gordon Fecyk said:

I don't suppose the "Stress The Devs" contest is still open for entries?

Nope, that contest is done now ... I won apparently

Anyways, here's my first attempt ... 517 dv short of orbit at around 77 000 meters

This is totally possible ... I'm pretty sure given some time someone will succeed in completing this challenge successfully

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So...

I did it. I don't know why I did it, this was challenge bait imho, but I did it anyway. Except I didn't do it as I used Mechjeb to control the craft and the challenge stated no mods. But then the challenge wasn't valid as the challenger didn't provide his own craft so it's my challenge now and I say Mechjeb is allowed. Mwahahahaha.

812 parts used. 494 tons. I called it Otto as in Orange Tank To Orbit. Thanks to @shirtandtieler as I saw his numbers and thought, that actually seems do-able. Completely impractical but do-able. And my design is far from optimal so I think this could be made into a low as possible part number or weight challenge. I can supply the craft file if really needed.

3 minutes ago, DoctorDavinci said:

This is totally possible ... I'm pretty sure given some time someone will succeed in completing this challenge successfully

Literally 10 seconds after you.

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3 minutes ago, Redshift OTF said:

So...

I did it. I don't know why I did it, this was challenge bait imho, but I did it anyway. Except I didn't do it as I used Mechjeb to control the craft and the challenge stated no mods. But then the challenge wasn't valid as the challenger didn't provide his own craft so it's my challenge now and I say Mechjeb is allowed. Mwahahahaha.

812 parts used. 494 tons. I called it Otto as in Orange Tank To Orbit. Thanks to @shirtandtieler as I saw his numbers and thought, that actually seems do-able. Completely impractical but do-able. And my design is far from optimal so I think this could be made into a low as possible part number or weight challenge. I can supply the craft file if really needed.

Literally 10 seconds after you.

Yes ... but you used MechJeb (good job on the successful orbit with mono though)

Anyways, at 517 dv short with a totally vanilla install, I am now king of the hill

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6 minutes ago, DoctorDavinci said:

Yes ... but you used MechJeb (good job on the successful orbit with mono though)

Anyways, at 517 dv short with a totally vanilla install, I am now king of the hill

Very true. I had to manually stage it though as Mechjeb couldn't compute when this was needed, I used the default flight path so it's probably not an optimal flight and I had to manually circularise so this craft could definitely get to orbit without Mechjeb if I had a faster computer. It was just so slow. Yours looks like it is almost there, perhaps use a central stage similar to mine get that extra push. One thing I noticed was the Puff engines get 90% of their thrust and isp at 10k meters so they are more powerful than they initially look.

Anyway, congrats!

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• 2 months later...

I'm impressed and we have a winner redshift otf I will allow mechjeb sorry i could not reply sooner

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16 hours ago, Mlg Dank Meme lord said:

I'm impressed and we have a winner redshift otf I will allow mechjeb sorry i could not reply sooner

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This challenge is bad for my health.

The basic rocket design is easy enough, it just needs a lot of stages, and a lot of parts.

So many, that my launch framerate drops to 1.2 MPF *

Why is it bad for my health?

The smoke coming off my graphics card is bad for the lungs, is it not?

* MPF = Minutes per Frame.

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