QnA someone with experience!

[ZooNamedGames]

I'm bored- so I'll answer any questions that new players may have.

All I ask is that questions are reasonable, please nothing that is too extreme (I'll provide an example of one when I see one).

[DaMachinator]

I built a very light probe lander, the Caduceus: https://kerbalx.com/DaMachinator/Caduceus

While I was designing it, I noticed something interesting:

Below a certain probe weight, the Ant engine gives the probe more Delta-V than the Spark engine, despite its' lower ISP. 

Does this have anything to do with the Spark also weighing considerably more than the Ant?

[ZooNamedGames]

2 hours ago, DaMachinator said:

I built a very light probe lander, the Caduceus: https://kerbalx.com/DaMachinator/Caduceus

While I was designing it, I noticed something interesting:

Below a certain probe weight, the Ant engine gives the probe more Delta-V than the Spark engine, despite its' lower ISP. 

Does this have anything to do with the Spark also weighing considerably more than the Ant?

Wow!  Someone finally posted here, and I just checked out of the blue!

As to your question, the Ant engine is a very specific use engine. With lower weights, it can get more use from the fuel it burns, however over a certain weight your gain in DV for every fuel tank is less. Once you cross the efficiency threshold, you'll need more power which is why the Spark is better for greater weight payloads.

In fact, in my opinion, the Spark is a heavily underestimated engine. People praise the LV-909 Terrier engine for it's efficiency, being lightweight and power, but the Spark engine is the same, but smaller and *slightly* weaker. I use it with 2.5m small payloads myself and it gives decent DV considering.

Hope this answers your question! If not, then I'll try better  .

[DaMachinator]

The Caduceus uses an LV-909 for the transfer stage and a Spark for the lander, which also does some of the insertion burn. The Spark has a slightly lower ISP than the LV-909 (230 or 240 vs. 245 IIRC)

And yes, that makes sense.

Edited July 1, 2016 by DaMachinator

[Andersenman]

On 1.7.2016 at 8:10 PM, ZooNamedGames said:

Once you cross the efficiency threshold, you'll need more power

Huh? What's an efficiency threshold?

[ZooNamedGames]

8 minutes ago, Andersenman said:

Huh? What's an efficiency threshold?

Well there's a point where your gain from more fuel with an engine becomes rapidly less and this "threshold" is where the additional weight is not worth the minute amounts of DV it provides.

[Andersenman]

Works for ion thrusters, so I don't see what you mean. Sure, the burntimes become impractical, but isp doesn't change with weight attached, so I can't follow.

Edited July 21, 2016 by Andersenman

[ZooNamedGames]

Just now, Andersenman said:

Works for ion thrusters, so I don't see what you mean. Sure, the burntimes become impractical, but isp doesn't change.

The ISP doesn't change, but the gain from additional fuels will drop off. Add 20 xenon tanks and you'll see the gain from the 21st to the 22nd tank is much smaller and will continue to grow smaller due to the additional weight of dry tanks and the additional fuel.

[Andersenman]

Ah, dry weight, of course. Thanks!

[ZooNamedGames]

5 minutes ago, Andersenman said:

Ah, dry weight, of course. Thanks!

Not a problem! It's why I have this thread  . Ask away, I'm always here to try and help.

[adsii1970]

Hmm, ok. Not a newbie by any means, but why is there not any launch towers?

 

[ZooNamedGames]

5 minutes ago, adsii1970 said:

Hmm, ok. Not a newbie by any means, but why is there not any launch towers?

 

There was, and people told them to get rid of it  .

[adsii1970]

[wumpus]

20 hours ago, adsii1970 said:

I think on the "things I hate about KSP" thread, players were *still* complaining about hitting the launch tower on the way up, long after it was gone.

[ZooNamedGames]

2 hours ago, wumpus said:

I think on the "things I hate about KSP" thread, players were *still* complaining about hitting the launch tower on the way up, long after it was gone.

I say they should've kept it, but have it tilted back like the vertical lifter used for the Titan rockets.

[JT531]

How do I jool?

[ZooNamedGames]

1 hour ago, JT531 said:

How do I jool?

Well first off, make sure your vessel has about 3km/s of delta V (or in lay mans terms, decent amount of fuel). 

Then launch with a 25° angle and continue to burn until you escape orbit (no need to go to orbit). Once you have broken free of Kerbin (typically about 2.6km/s-2.9km/s).

Then burn at your periapsis around the sun until you get an encounter. This isn't an efficient method, but it's effective to getting that first encounter. 

Once you've got one, then warp to to enter it. Then reach your Jool periapsis and burn retrograde until you've been captured! Then your in Jool orbit! As to the specifics of where you want to go that's a different discussion; one I can do but not in this response.

[JT531]

lemme hit you with another one...

What is the mass of a neutron star the size of a pear if it were teleported to the middle of the sea floor on earth, while the earth was at its aphelion during a solar eclipse?

[ZooNamedGames]

5 hours ago, JT531 said:

lemme hit you with another one...

What is the mass of a neutron star the size of a pear if it were teleported to the middle of the sea floor on earth, while the earth was at its aphelion during a solar eclipse?

Well that would go under the no unreasonable questions  .

[JT531]

On 7/24/2016 at 8:14 PM, ZooNamedGames said:

Well that would go under the no unreasonable questions  .

Exactly! I just provided you with an example! Now you can use it!

[ZooNamedGames]

2 minutes ago, JT531 said:

Exactly! I just provided you with an example! Now you can use it!

Thanks  !

[ZooNamedGames]

Also for reference to my demishing returns of DV with larger rockets refer to this thread where it's discussed.

 

Edited July 29, 2016 by ZooNamedGames

[JT531]

In RSS, how many km/s do I need to do a flyby of mars?

 

[ZooNamedGames]

18 minutes ago, JT531 said:

In RSS, how many km/s do I need to do a flyby of mars?

 

Probably 8km/s on top of what's needed to make Earth escape.

Edited July 30, 2016 by ZooNamedGames

[NathanKell]

Sorry, that's...not really true. I highly recommend looking at the wikipedia article on delta V budgets or a delta V map of the solar system. It's worth noting however that those are optimal values; the actual numbers will depend on the exact window.