New and a few questions : )

[Smallish]

Hello everyone o/

I have around 100 hours in learning to blow stuff up and examine goo. I feel like I'm doing pretty well, I've landed and returned to both of the Kerbin Moons and orbited Duna and returned, but I have some burning questions that the more learned may like to help me understand, so here we are :

1. I realize in my innocent way that adding more and fuel will eventually prevent take off. However, if I have a "single unit of space ship", say a fuel tank, a module and an engine - and it is capable of take off and some acceleration, surely I could add a million of them and all the while I would be increasing my overall DeltaV... Am I right to think that? I mean, I could just keep adding Jet engines and keep getting an equal benefit from each?

2. Is there any reason to decrease throttle as you get higher (to orbit) or should you actually try to accelerate as hard as possible to get to orbit as quick as possible?

3.I have access to the Nuclear engines, and have changed to a triple standard size fuel tank setup from a Rockomax size to allow me to use 3 engines instead of one. This has allowed me to get an out and return to Duna, but how (in a nutshell) can I get to land on Duna (or other planets) without a lander and punchy engines for takeoff. If I want to take a lander and all that, I can't imagine how I'm going to get it a) into orbit over Kerbin and all the way to a planet with enough fuel for a return, and not to mention the retrograde burn to slow down to orbit the planet...

4. How can I tell if I'm gaining or losing by adding more or taking off fuel? I did see a DeltaV calculation mod and am wondering whether this will actually aid in this situation, but how does it account for engines that are on your ship and not used for take off? also, is Deltav the be all and end all?

5, Is it feasible to have a space station where you can deposit fuel for a future long passage? I don't know if it's possible to transfer fuel in this way even...

Well I have many questions actually, and am a bit confused about a few things, but this will do for a start : )

Thank you

[sjwt]

1. I realize in my innocent way that adding more and fuel will eventually prevent take off. However, if I have a "single unit of space ship", say a fuel tank, a module and an engine - and it is capable of take off and some acceleration, surely I could add a million of them and all the while I would be increasing my overall DeltaV... Am I right to think that? I mean, I could just keep adding Jet engines and keep getting an equal benefit from each?

To a small point, as the total mass increases so do your overheads, also as thrust goes up so does air resistance, eventually you lose out or get so little advantage that your PC crawls from FPS(Frames per second) to SPF(Seconds per frame) mode or you even lose DV by adding more.

2. Is there any reason to decrease throttle as you get higher (to orbit) or should you actually try to accelerate as hard as possible to get to orbit as quick as possible?

Hard and fast, get out of that gravity and air as fast as possible, you lose 1G* every second you are not orbiting - *(May or may not be true no idea on the loss but that's just for example)

3.I have access to the Nuclear engines, and have changed to a triple standard size fuel tank setup from a Rockomax size to allow me to use 3 engines instead of one. This has allowed me to get an out and return to Duna, but how (in a nutshell) can I get to land on Duna (or other planets) without a lander and punchy engines for takeoff. If I want to take a lander and all that, I can't imagine how I'm going to get it a) into orbit over Kerbin and all the way to a planet with enough fuel for a return, and not to mention the retrograde burn to slow down to orbit the planet...

Using the docking ports you should carry a lander craft that is capable of returning to orbit. Like the Luna lander, as light as possible to reduce dead weight.

4. How can I tell if I'm gaining or losing by adding more or taking off fuel? I did see a DeltaV calculation mod and am wondering whether this will actually aid in this situation, but how does it account for engines that are on your ship and not used for take off? also, is Deltav the be all and end all?

Mechjeb can calculate DV for you. It will be able to show you DV per stage and total DV so you can work on things like halving your upper stages fule to see that may add to your total DV see this image for some DV stats.

5, Is it feasible to have a space station where you can deposit fuel for a future long passage? I don't know if it's possible to transfer fuel in this way even...

Yes, with docking ports, once you dock you can transfer fuel as needed.

Well I have many questions actually, and am a bit confused about a few things, but this will do for a start : )

Thank you

Welcome, and please enjoy your stay

[Smallish]

To a small point, as the total mass increases so do your overheads, also as thrust goes up so does air resistance, eventually you lose out or get so little advantage that your PC crawls from FPS(Frames per second) to SPF(Seconds per frame) mode or you even lose DV by adding more.

Hard and fast, get out of that gravity and air as fast as possible, you lose 1G* every second you are not orbiting - *(May or may not be true no idea on the loss but that's just for example)

Using the docking ports you should carry a lander craft that is capable of returning to orbit. Like the Luna lander, as light as possible to reduce dead weight.

Mechjeb can calculate DV for you. It will be able to show you DV per stage and total DV so you can work on things like halving your upper stages fule to see that may add to your total DV see this image for some DV stats.

Yes, with docking ports, once you dock you can transfer fuel as needed.

Welcome, and please enjoy your stay

Thank you for the answers.

About the Lander, if I have a lander, how do I make a pre flight judgement about how much fuel the lander should carry? As Duna is my target at the moment, I know the gravity is lower by some degree than Kerbin, but what about the amount of fuel I'll need to get back to the mother ship...And I can't imagine how many months I'll spend trying to dock : ) but that's another problem }:-|

[SRV Ron]

You need not build big, just build efficiency. Example, a 10 part challenge using a rocket with a Skipper engine, orange fuel can, decoupler, LV-N engine, FL-T800 fuel can, decoupler, capsule, parachute, made a one way trip to Eve, Duna, Laythe, and several of the smaller moons around Jool as well as a Voyager escape.

[Taki117]

1. I realize in my innocent way that adding more and fuel will eventually prevent take off. However, if I have a "single unit of space ship", say a fuel tank, a module and an engine - and it is capable of take off and some acceleration, surely I could add a million of them and all the while I would be increasing my overall DeltaV... Am I right to think that? I mean, I could just keep adding Jet engines and keep getting an equal benefit from each?

Thanks to the Rocket Equation you will eventually reach a point of diminishing returns, as you add more fuel your total dV will not increase as much. Yes you could continue adding engines, but if you don't drop them when they run out of fuel then you are just shooting yourself in the foot because once they are out of fuel they are providing no thrust and are just dead weight. (This is why the Shuttle doesn't keep it's SRBs, once they run out there's no point in keeping them, same goes for any other rocket)

2. Is there any reason to decrease throttle as you get higher (to orbit) or should you actually try to accelerate as hard as possible to get to orbit as quick as possible?

Besides fuel efficiency? Yes! As you increase speed you also increase dV losses due to drag if you are above terminal velocity. Terminal Velocity is the point at which your dV loss due to air resistance is about equal to your dV losses due to gravity. Any faster and you are wasting dV fighting air resistance, any slower and you are wasting dV fighting gravity. At this point you should begin to throttle back to maintain terminal velocity for maximum launch efficiency.

3.I have access to the Nuclear engines, and have changed to a triple standard size fuel tank setup from a Rockomax size to allow me to use 3 engines instead of one. This has allowed me to get an out and return to Duna, but how (in a nutshell) can I get to land on Duna (or other planets) without a lander and punchy engines for takeoff. If I want to take a lander and all that, I can't imagine how I'm going to get it a) into orbit over Kerbin and all the way to a planet with enough fuel for a return, and not to mention the retrograde burn to slow down to orbit the planet...

I direct you here for my Duna Mission, please note this ship was WAY over engineered (some 6km/s dV) so I had more than enough to get back. The easiest way to build interplanetary ships is to build them in Orbit (As I did for my mission, kinda) if you are going to Duna, Eve, Jool, Laythe, or back to Kerbin, you can use a technique known as aero-braking/aero-caputre, where you dip down into the atmosphere of the body you are approaching and use atmospheric drag to slow you down enough without having to do a retrograde burn to slow down. However, that being said if you try this on an airless world you will lithobrake.

4. How can I tell if I'm gaining or losing by adding more or taking off fuel? I did see a DeltaV calculation mod and am wondering whether this will actually aid in this situation, but how does it account for engines that are on your ship and not used for take off? also, is Deltav the be all and end all?

MechJeb and Kerbal Engineer are two of the best dV calculators out there. Since engines that are not used for liftoff aren't used at all for that stage they are not taken into account for that stage. both MechJeb and KER separate out your crafts dV by stages so that you can see how much dV each stage is giving you, they also provide a total dV for the craft that basically adds up all the stages dV to give you a total. dV is not the end all be all, there is also TWR (Thrust to Weight Ratio). IF you are trying to liftoff from a body and your TWR is <1 you will not go to space today, if you are in space and you have a low TWR your burn times will be horrendous (read: extremely very long). Hence why I have the booster stage on my Duna mission. IT has a TWR >1 where as the main drive stage has a TWR of about .5, but when I get to Duna that goes up to about .8, which isn't as bad. In deep space TWR isn't as important because a burn time of a half-hour isn't going to be affected by your position in orbit as much as it would around a planet.

5, Is it feasible to have a space station where you can deposit fuel for a future long passage? I don't know if it's possible to transfer fuel in this way even...

Absolutely! In order to transfer fuel between fuel tanks ON THE SAME VESSEL (Docked vessels count as the same vessel for this purpose) all you have to do is right click the first fuel tank, and ALT+RMB the second fuel tank. You should see little in and out buttons pop up. All you have to do then is pick a tank you want to go into or out of and click the corresponding button and watch as fuel magically goes into or out of said tank.

[Taki117]

Thank you for the answers.

About the Lander, if I have a lander, how do I make a pre flight judgement about how much fuel the lander should carry? As Duna is my target at the moment, I know the gravity is lower by some degree than Kerbin, but what about the amount of fuel I'll need to get back to the mother ship...And I can't imagine how many months I'll spend trying to dock : ) but that's another problem }:-|

Sorry for the double post, but I direct you here This is what's known as a dV Map. Think of it like a rad map telling you exactly how much dV you need to get to anywhere in the solar system! Just add up all the numbers from where you are to where you are going (And if you are following red arrows ignore the numbers) and that is how much total dV you need. So to get to and from the surface of Duna your lander (And only your lander) just have just over 1300m/s of dV. I say just over because you need some dV to cause your lander to dip into the atmosphere to begin with.

[Smidge204]

However, if I have a "single unit of space ship", say a fuel tank, a module and an engine - and it is capable of take off and some acceleration, surely I could add a million of them and all the while I would be increasing my overall DeltaV...

If you took ten identical units and stuck them together and fired them all at the same time, it would go almost exactly as far as a single unit would go. Sure you've doubled the thrust, but you've also doubled the mass, and so your acceleration and dV (which is based on the ratio of full and empty ship mass) would be the same.

But through the magic of asparagus staging, you can turn that strategy into something quite impressive.

2. Is there any reason to decrease throttle as you get higher (to orbit) or should you actually try to accelerate as hard as possible to get to orbit as quick as possible?

You might want to throttle back to maintain control of your launch. A good ascent profile results in a low, circular orbit... so maybe you want to throttle back to avoid lifting your orbit too high before you have a chance to turn. That's the only reason I can think of, though.

I have access to the Nuclear engines, and have changed to a triple standard size fuel tank setup from a Rockomax size to allow me to use 3 engines instead of one. This has allowed me to get an out and return to Duna, but how (in a nutshell) can I get to land on Duna (or other planets) without a lander and punchy engines for takeoff.

MechJeb and Kerbal Engineer Redux are mods that will give you detailed statistics for your craft as you build it. With this, you can plan a craft that has enough fuel to do whatever.

My advice: Try to leave the nukes in orbit. You CAN land on Duna with nukes, and return to orbit, but it's really not what they're for.

Sorry I don't have a better picture, but:

The tanks are set up so empty ones can be discarded to keep dV high. The nuclear end has a small probe core and RCS and I actually dock the interplanetary stage to the lander, not the other way around... that lets me keep the lander light.

Is it feasible to have a space station where you can deposit fuel for a future long passage? I don't know if it's possible to transfer fuel in this way even...

Yes! Here's a pair of space planes stopping off for a refueling:

You need not build big, just build efficiency. Example, a 10 part challenge using a rocket with a Skipper engine, orange fuel can, decoupler, LV-N engine, FL-T800 fuel can, decoupler, capsule, parachute, made a one way trip to Eve, Duna, Laythe, and several of the smaller moons around Jool as well as a Voyager escape.

Hey! That's my design with some extra parts!

=Smidge=

[Smallish]

@SRV Ron...this makes my out and back non lander to Duna look a "little" over powered, I have 9 times the fuel that you have there : | I do have a fair bit of science stuff and 3 engines to avoid the long burns though... I have made the first burn to intercept Duna and I can't see that the fuel levels have Dropped! ... Maybe I'll add a tour of the Duna moon. I can tell you, to get it off into orbit took an incredible amount of energy.

@Taki. I do stage my engines and drop them as they become redundant of course, my Duna ship with 6 stacks of rockomax tanks is literally rammed with jet engines in a ring, they seem to work up to 30,000m, so it seems like free power (I have set them to shut down and de couple with an action group infact I'll load the photo... the central stage i en route to its encounter...

I will review your mission in detail, it looks very interesting at first glance! Just quickly though, is it painful to keep docking with satellite objects? It looks pretty skilled to be able to dock with something, if you're having to do it a lot it must be extremely time consuming?

I downloaded and installed Kerbal engineer,I just need to understand what it means now, but all in good time.

Thank you for the Dv map, I'll enjoy putting that to use!

[EtherDragon]

Hello everyone o/

I have around 100 hours in learning to blow stuff up and examine goo. I feel like I'm doing pretty well, I've landed and returned to both of the Kerbin Moons and orbited Duna and returned, but I have some burning questions that the more learned may like to help me understand, so here we are :

1. I realize in my innocent way that adding more and fuel will eventually prevent take off. However, if I have a "single unit of space ship", say a fuel tank, a module and an engine - and it is capable of take off and some acceleration, surely I could add a million of them and all the while I would be increasing my overall DeltaV... Am I right to think that? I mean, I could just keep adding Jet engines and keep getting an equal benefit from each?

Adding more Rocket Engines increases Thrust and will improve thrust to weight ratio, but actually decreases your total Delta-V.

This video explains why:

2. Is there any reason to decrease throttle as you get higher (to orbit) or should you actually try to accelerate as hard as possible to get to orbit as quick as possible?

It depends - as long as you aren't going faster than terminal velocity, you're fine.

Here's another video that explains why to care about ascent speed (among other things):

3.I have access to the Nuclear engines, and have changed to a triple standard size fuel tank setup from a Rockomax size to allow me to use 3 engines instead of one. This has allowed me to get an out and return to Duna, but how (in a nutshell) can I get to land on Duna (or other planets) without a lander and punchy engines for takeoff. If I want to take a lander and all that, I can't imagine how I'm going to get it a) into orbit over Kerbin and all the way to a planet with enough fuel for a return, and not to mention the retrograde burn to slow down to orbit the planet...

Nuclear engines are for interplanetary travel - not really for descent or ascent. The best method seems to be to bring along a lander capable of reaching the surface, and ascending Duna all on it's own - to dock with your Nuclear-Engine equipped Mother ship in orbit.

4. How can I tell if I'm gaining or losing by adding more or taking off fuel? I did see a DeltaV calculation mod and am wondering whether this will actually aid in this situation, but how does it account for engines that are on your ship and not used for take off? also, is Deltav the be all and end all?

There are mods to see the effect of adding subtracting fuel and mass has on Delta-V. But the main factors are (from the video above) the more efficient the engine - the more delta-V AND the higher your Fuel to Mass ratio the more delta-V. But Fuel-to-Mass ratio diminishes in return rather quickly. It actually turns out that the best way to maximize delta-V is to do three things: Use efficient Engines, Have a relatively high Fuel to Mass Ratio (but no need to go insane), AND use frequent stating to ditch empty mass once fuel is expended.

5, Is it feasible to have a space station where you can deposit fuel for a future long passage? I don't know if it's possible to transfer fuel in this way even...

Absolutely, lots of players here have permanent refueling stations spotted around the Kerbol system.

Well I have many questions actually, and am a bit confused about a few things, but this will do for a start : )

Thank you

YW!

[Smallish]

The wealth of knowledge I've realized after reading all this is great.. I've just gone from a 7.9k Dv to 13.7k with my inter planetary science voyager..Well, it wasn't rocket science - oh wait, it was : )

Now to make a planetary lander and work on my docking skills. Thanks all

[Taki117]

The wealth of knowledge I've realized after reading all this is great.. I've just gone from a 7.9k Dv to 13.7k with my inter planetary science voyager..Well, it wasn't rocket science - oh wait, it was : )

Now to make a planetary lander and work on my docking skills. Thanks all

GASP! You could probably make it back from almost every planet in the solar system (Except maybe Jool) Congrats. Also, Don't forget to strut!