Is it worth using the nuclear engine on duna?

[jamieadd]

Does anyone know what the efficiency of the nuclear engine is on the surface of duna, and if it is worth using them.

[RoboRay]

The LV-N's Isp at the datum on Duna is still over 700s.

[bulletrhli]

I did not know LV-N had a high ISP on Duna!?

[jamieadd]

That was quick.

Thanks

[The Destroyer]

It is quite good, I remember using it for a Duna return mission. Due to having little atmosphere, it still has extreme effectiveness, not to mention the lowish gravity of Duna.

[Wjolcz]

i use lv-ns for everything

[bulletrhli]

It is quite good, I remember using it for a Duna return mission. Due to having little atmosphere, it still has extreme effectiveness, not to mention the lowish gravity of Duna.

Well, I am glad someone else has tested it and said it because if it wasn't for this thread, I would of had no idea. I tend to use atmospheric engines or something like a poodle for landing in atmospheres.

[automcdonough]

i think it still depends on size of the craft. if it's small enough then the extra 2t of weight is a big deal.

[Francesco]

depends on what you have to do on Duna, and if you have to get back to Kerbin.

also, spacecraft mass is relevant: for small ships, like a 1-man lander, smaller engines like the LV-909 are still the better choice.

but yes, due to Duna's thin atmosphere, you get an almost in vacuum ISP.

[jamieadd]

I was thinking of having a shuttle from orbit to the surface, with a payload of about 20 kerbin tons

[Crush]

The LV-N isn't that good of a choice for landers.

1. it's important for a lander that its acceleration is considerably higher than the gravity of the planet, because the gravity is subtracted from it during ascent and descent. In order to get a good acceleration, you need an engine with a good thrust-to-weight ratio, and that of the LV-N is by far the worst of all.

2. It is very long, making it hard to integrate into most lander designs.

Edited June 10, 2013 by Crush

[-RanZ-]

I bet a LV-N on a plane would work great for Duna, you could have a controlled decent and use almost no fuel for landing and even with a low TWR the LV-N should be able to get you off the planet fine. I may try this tonight, make a really small plane with a nuke and see if I can get to Duna and back.

[Crush]

That could indeed work. Acceleration doesn't matter that much on a plane, because you can substitute it with lift while you are in the atmosphere, and when you leave the atmosphere in a flat angle you already have enough horizontal speed that you don't experience much gravity drag anymore when you exit the atmosphere.

Edited June 10, 2013 by Crush

[-RanZ-]

Only problem is Duna has a very thin atmosphere, I am guessing you will get enough lift from the wings to maybe get the plane vertical so you would have to have it light enough for the nuke to get you into orbit.

[MasterFlyer6626]

How do I delete this?

Edited June 10, 2013 by MasterFlyer6626

[MasterFlyer6626]

The LV-N isn't that good of a choice for landers.

1. it's important for a lander that its acceleration is considerably higher than the gravity of the planet, because the gravity is subtracted from it during ascent and descent. In order to get a good acceleration, you need an engine with a good thrust-to-weight ratio, and that of the LV-N is by far the worst of all.

2. It is very long, making it hard to integrate into most lander designs.

But For Duna, you can use para chutes.

[MasterFlyer6626]

i use lv-ns for everything

Even for Eve aircraft?!

[numerobis]

I'm calculating 336 Isp at Laythe sea level -- not nearly as good as jets, but pretty decent for a rocket.

[Spartwo]

simply yes.the lowest isp is around the 730 mark.the lower gravity means that 2 is the equivillent of the white radials making getting into orbit even returning not that hard.

[Procyon]

kerbin ton's = KT's or kerton's ?

[royying]

http://wiki.kerbalspaceprogram.com/wiki/Duna

altitude (m) 2 100 300 500 1460 2420 3000 4272 5000 10000

specific impulse 684.1 687.8 695.1 701.8 728.7 748.2 757.3 772.1 778.1 795.9

[Mephane]

Do not underestimate the efficiency of the LV-N. Even in Kerbin's atmosphere, at around 2km above sea level it reaches an ISP of 400, thus outperforming any other engine. If you ship has LV-Ns, you should consider igniting them at about that height. Best way to do this is action groups, as they tend to overheat in atmospheres and usually you do not want to throttle down during a launch. Just turn them off when the heat gets too high, they will cool down within seconds and can be fired again. The additional thrust is not much, but very cheap on fuel.

Edited June 14, 2013 by Mephane

[The Destroyer]

Well, I am glad someone else has tested it and said it because if it wasn't for this thread, I would of had no idea. I tend to use atmospheric engines or something like a poodle for landing in atmospheres.

God, I remember trying 10 times to land a DEMV MK2 in 0.17. I was using jets to slow down, but it wasn't working. Turns out jet engines don't work on Duna, only laythe and Kerbin *facepalm*

Finally realised that and got aerospikes.

[entaran]

You can use kethane jets on Duna just fine.

[RoboRay]

Well, I am glad someone else has tested it and said it because if it wasn't for this thread, I would of had no idea. I tend to use atmospheric engines or something like a poodle for landing in atmospheres.

The air pressure at the surface of Duna is equivalent to Kerbin's air pressure at 10-12km up (depending on surface height above the datum), so the LV-N is a great performer.

That said, the LV-N isn't a good lander engine due to it's size and weight. The only reason you should use the LV-N for a lander is if that "lander engine" is the same motor you use for interplanetary propulsion. So, a Duna lander that left the main fuel tanks and other bulky parts of the "mothership" in orbit and visited the surface with just the drive section and a crew cabin would be a reasonable design. A lander with an LV-N that was not used for interplanetary flight while the mothership had its own LV-Ns would not be a very good design.

Edited June 11, 2013 by RoboRay