How to make this rocket more efficient

[Metro]

Hello KSP Community,

I, as an beginner, want to go for another mün landing to rescue my Kerbal which is stranded out there. For this, I managed to build a rocket with a Delta-V of 8161. After changing the order of the used engines and a few fuel tanks the total Delta-V decreased rapidly. Here's how my rocket looks like

Pretty ineffective because I just started

Saving of the rocket can be downloaded from here

http://en.file-upload.net/download-8881449/M1.7z.html

Bonus Question - to find out how much Delta-V I need to fly back to Kerbin do I have to calculate 580+230+80+180?

https://i.imgur.com/UUU8yCk.png

Thanks in advance!

Edited May 4, 2014 by Metro
Pretty much answered. Thanks!

[Taki117]

You should move those 2nd stage radial tanks down to the first stage, they are just extra weight up there. Also, your lander doesn't need that much fuel either.

This rocket will get you there and back

To answer your second question you can drop the 180 since you are simply aerobraking to landing (I am assuming)

[LethalDose]

Hi Metro, welcome to the forums. I'd give you the following advice:

1. Change the engine on the upper stage to the LV 909
   
2. Increase the fuel in the lowest stage
   
3. Lose the radial tanks and engines on the upper stage. Without fuel ducts, they're aren't giving you much.
   

Also, you may want consider "tweaking" the max throttle on the SRBs. Tweaking is done by right clicking on the part and adjusting the slider.

If you're mission is to rescue a stranded kerbal on the Mun, you'll need extra crew space in your return rocket. As it stands, you only have room for one Kerbal. I'd recommend unlocking the probe core and attaching to the top of this rocket. That way, you can fly the rocket to the Mun unmanned, and back with the kerbal in the pod.

8 km/s of dV is a LOT, and should be sufficient to get the Mun's surface and back. Instead of modifying your craft to be more efficient, it may make more sense to discuss what's happening at various stages of your mission, first.

[LethalDose]

You should move those 2nd stage radial tanks down to the first stage, they are just extra weight up there. Also, your lander doesn't need that much fuel either.

This rocket will get you there and back

To answer your second question you can drop the 180 since you are simply aerobraking to landing (I am assuming)

That's an excellent rocket you've linked, but I don't think the OP has the tech to construct it (I don't think he has the tri-coupler structural part). However, four SRB's around a liquid fuel core like he has may be enough to get him there.

Overall, Metro, looking at your tech tree, it may be a little early for you to attempt a Mun landing. Have you tried a Minmus fly-by? The good news is, in stock KSP (no mods) you're Kerbals won't run out of oxygen, so you can recover him at your leisure.

Safe skies!

[Metro]

You should move those 2nd stage radial tanks down to the first stage, they are just extra weight up there. Also, your lander doesn't need that much fuel either.

This rocket will get you there and back

To answer your second question you can drop the 180 since you are simply aerobraking to landing (I am assuming)

Great tips, thank you!

Hi Metro, welcome to the forums. I'd give you the following advice:

1. Change the engine on the upper stage to the LV 909
   
2. Increase the fuel in the lowest stage
   
3. Lose the radial tanks and engines on the upper stage. Without fuel ducts, they're aren't giving you much.
   

Also, you may want consider "tweaking" the max throttle on the SRBs. Tweaking is done by right clicking on the part and adjusting the slider.

If you're mission is to rescue a stranded kerbal on the Mun, you'll need extra crew space in your return rocket. As it stands, you only have room for one Kerbal. I'd recommend unlocking the probe core and attaching to the top of this rocket. That way, you can fly the rocket to the Mun unmanned, and back with the kerbal in the pod.

8 km/s of dV is a LOT, and should be sufficient to get the Mun's surface and back. Instead of modifying your craft to be more efficient, it may make more sense to discuss what's happening at various stages of your mission, first.

Thanks for your welcome first. I will try to implement your tips as well. I was pretty happy to reach 8 km/s of dV, but after trying to optimize my rocket I killed it. My new rocket which I'm currently working on (the one I posted above) is based on another with just enough dV to get to the moon. I'm not sure if the fuel which I left will be enough to go home, is there a formula for calculating that again?

http://picload.org/image/lllwcrp/unbenannt.png

That's an excellent rocket you've linked, but I don't think the OP has the tech to construct it (I don't think he has the tri-coupler structural part). However, four SRB's around a liquid fuel core like he has may be enough to get him there.

Overall, Metro, looking at your tech tree, it may be a little early for you to attempt a Mun landing. Have you tried a Minmus fly-by? The good news is, in stock KSP (no mods) you're Kerbals won't run out of oxygen, so you can recover him at your leisure.

You're right, I don't have the tri-coupler structural part yet. Since my rocket doesn't have enough room for another Kerbal it's impossible to do the rescue anyway, so you're right. I will try to get some science points first.

We have a great community here

Edited May 4, 2014 by Metro

[UmbralRaptor]

I'm not sure if the fuel which I left will be enough to go home, is there a formula for calculating that again?

The rocket equation

For KSP purposes, you want Isp*9.82*ln(Initial_mass/final_mass). You can find the initial (well, current) mass of the craft in map view. For final mass, I would subtract the fuel and oxidizer masses (mass being fuel units/200)

I don't have the tri-coupler structural part yet. Since my I don't have enough room for another Kerbal it's impossible to do the rescue anyway, so you're right.

I'd lean towards just radially connecting the tanks to get larger lower stages. (Pic is of a craft with demo parts, but you effectively have all the tech. Shame it runs critically low on ÃŽâ€V if you start hanging goo pods or material bays off of it...)

[SRV Ron]

This early design has enough delta V to do Mun or Minmus orbit and return.

And, KSP 0.23.5

[Metro]

The rocket equation

For KSP purposes, you want Isp*9.82*ln(Initial_mass/final_mass). You can find the initial (well, current) mass of the craft in map view. For final mass, I would subtract the fuel and oxidizer masses (mass being fuel units/200)

I'd lean towards just radially connecting the tanks to get larger lower stages. (Pic is of a craft with demo parts, but you effectively have all the tech. Shame it runs critically low on ÃŽâ€V if you start hanging goo pods or material bays off of it...)

Ahh, sorry. I failed. However, under Terminology about Isp it says following

"To avoid confusion which unit of speed is used, the physical correct I_sp (in distance/time) is divided by the surface gravity of Earth (9.81 m/s²). This results in a value given in seconds. To use this I_sp in formulas it must to be converted back into distance per time which requires multiplying with the surface gravity of Earth again."

While under the Advanced Rocket Design page it's says something else

"If the specific impulse is given in seconds it is necessary to multiply this value by "

As far I understand I, even though I'm on the mun, still have to use 9.82?

@SRV Ron Amazing!!!

Edited May 4, 2014 by Metro

[UmbralRaptor]

Yep, the constant g0 is based on units, and never varies based on location. The 9.82 is just what I've gotten from checking the resources tab with various engines. It is not clear why this is the value, rather than 9.81 (typo in the source code?). But nonetheless...

[KerikBalm]

Since my I don't have enough room for another Kerbal it's impossible to do the rescue anyway

Not true, you can make room for another kerbal by adding a second command pod (make sure no one is sitting in it at launch). Of course, later, you can just slap a probe core on it, and launch with 1 empty pod, but for now a rescue means you must take two pods

Here you go:

https://www.dropbox.com/s/ra3r08huizh01ab/Mun%20Rescue.craft this should get you there.

I had a smaller craft, it was a bit more complex with action groups, and required a pretty optimal ascent ot orbit.

This one is simpler to fly.

Full throttle, fire engines

As the 1st stage gets lighter, throttle back to maintain optimal ascent velocity

When the SRBs run out of fuel, full throttle, and keep it that way until you're in orbit

After landing on the Mun next to your kerbal, have him get in the other pod.

Here's where It gets a little needlessly complex - while you should have plenty of dV remaining, in case you find yourself a bit short:

The central stack of 2 FL-T200s-> transfer that fuel into the side mounted FL-T400s (the ones under the command pods), then as you're at nearly low mun orbit, fire the decoupler.

You've shed some mass, and now have 2 separate ships, your stranded Kerbal is a rocketman after all, and wants to take his own rocket home, not just be a passanger on someone else's rocket

Fly each one back to Kerbin.

Edited May 4, 2014 by KerikBalm

[Metro]

Not true, you can make room for another kerbal by adding a second command pod (make sure no one is sitting in it at launch). Of course, later, you can just slap a probe core on it, and launch with 1 empty pod, but for now a rescue means you must take two pods

Here you go:

https://www.dropbox.com/s/ra3r08huizh01ab/Mun%20Rescue.craft this should get you there.

I had a smaller craft, it was a bit more complex with action groups, and required a pretty optimal ascent ot orbit.

You're right with the second command pod, I sometimes really should open my mind more.

Thank you for your aircraft as well! Could you tell me what parts you're using which I don't have yet or make a ScreenShot of the craft, please? I'm currently trying to get some science points

[Metro]

It is not clear why this is the value, rather than 9.81 (typo in the source code?). But nonetheless...

I've found out why. If we look closly, it says that the gravity of Earth is used, not Kerbin's (makes it a bit more confusing though, because the name of the rocket is Mun Lander, not Moon Lander)

"Following is a quick example, where the surface gravity of Earth is used:"

Link: http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

[KerikBalm]

Hrmm, I don't know why it says the parts are invalid, I tried to use only parts I saw you use in the screenshot you posted.

Try opening it in a sandbox game? if not, I wonder if I modded one of the parts and forgot about it.

I'll show a screenshot later today

[Javster]

How will you get the stranded Kerbal back with only one pod?

[michaelhester07]

You at least know delta V so that's good. Heres a number you might want to know:

2500 km/s

That's how much delta V I've needed to land on the mun and return from it. You need to get to the mun with more than this to guarantee a safe return. If someone did it with less dV then they can tell you how.

I'll help you redesign it here.

1. Command module:

1x command pod mk1, 1x parachute, 2x stack separator, 1x 400 size tank, 1x Lv909, 3x landing gear

Assembly top to bottom:

parachute, command pod, stack separator, 400 tank, landing gear, lv909, stack separator

Make sure the extended gear goes beyond the bottom of the 909. That engine can't take an impact like the gear can.

2. Transfer stage

1x 800 size tank, 1x Lv 30, 3x radial stack separator

Assembly top to bottom:

800 tank, 3x radial stack separator, 1x lv 30

The radial separators should be near the top of this section about 1/3 of the way down the tank. Attach this stage to the bottom of the command module.

3. Orbit insertion stage

1x 400 tank, 1x 800 tank, 1x lv30, 3x radial separator

Top to Bottom:

400 tank, 800 tank, radial separator, lv45

The orbit insertion stage is the first stage built out radially. The 3 radial separators should be at 90, 180, and 270 degrees from the attachment point to the transfer stage. Keep them at the same height up the rocket level with where the transfer stage's engine is.

4. Launch stage

2x 400 tank, 2x 800 tank, 2x LV45, 1x long SRB

Liquid booster top to bottom

400 tank, 800 tank, lv45

Liquid booster attaches to the 90 and 180 separators from the orbit insertion stage.

SRB attaches to the 180 degree separator.

Setting the stages: The editor should do a good job at setting up the stages for you. see that it matches this order

0: parachute

1: top stack separator

2: lv909

3: middle stack separator

4: transfer stage lv 30

5: inner most radial separators

6: orbit insertion lv 30s

7: 90/270 separators (has the liquid engines attached)

8: 180 separator (has the srb attached)

9: launch stage lv 45s and srbs

Launching/flying:

Start with the liquid engines at 40% throttle. Engage SAS and launch.

Let the SRBs burn out and separate them before doing your gravity turn. Once the SRBs separate throttle to full.

At 10km altitude turn to heading 90 45degrees altitude. Burn here until your apoapsis is t+60 seconds then burn toward the prograde vector.

When your apoapsis altitude (i like to burn to this) is at 100km cut the engines. There might be some of your launch stage left if you didn't start burning into your orbit insertion stage.

Add a maneuver node at the apoapsis to establish an orbit. This should take the rest of your launch stage and most of the orbit stage. You'll use anything left in the orbit insertion stage to boost you to the moon.

Plan a moon intercept node. Use the rest of the orbit insert stage and some of your transfer stage to burn this node. The rest of the transfer stage will be used to establish orbit around the moon. If you plan your moon intercept node such that you get to the moon when it is a first quarter moon you can land immediately without having to orbit it. Otherwise use the rest of the transfer stage to establish an orbit. You might have a little extra dV to start the descent. Happy landing from there!

With this early of a tech try to avoid heavy turning. Once you cut lose the transfer stage you won't get any more electrical power. Tell Jeb to put an alternator in the next version of the LV909

Edit: I tried this ship out last night with a new career. By T2 of everything and without that T3 engine upgrade I was able to build the ship. I managed to get to Mun with 5000 dV but no landing gear. I got a low enough orbit that I could take EVA reports as "flying over" a biome. I could chain enough biomes to get 120 science out of the trip. If i had landing gear I could have landed. In a later version of the ship I did land.

Edited May 6, 2014 by michaelhester07
i tested the ship.

[Metro]

Hrmm, I don't know why it says the parts are invalid, I tried to use only parts I saw you use in the screenshot you posted.

Try opening it in a sandbox game? if not, I wonder if I modded one of the parts and forgot about it.

I'll show a screenshot later today

Alright, even after unlocking some new stuff it still says bad parts. I'll see what's in it in sandbox and edit it in this post

I'll help you redesign it here.

Very nice, thank you!

[KerikBalm]

*edit* AHHHHH....... I seee..... I used the wrong landing legs!

I used the heavier ones anyway, so it should work even better

Also, I forgot to mention, since you don't have RCS thrusters, drain all the monoprop from the command pods before launching them(do it in the VAB with the tweakables), that'll get you a little bit more of a margine

You're right with the second command pod, I sometimes really should open my mind more.

Thank you for your aircraft as well! Could you tell me what parts you're using which I don't have yet or make a ScreenShot of the craft, please? I'm currently trying to get some science points

Well... took me longer to get around to it than I said, but here is the craft I made:

1st stage engines firing: 4x rockomax SRBs, 1x LV-T45, 2x LV-T30s

2nd stage: SRBs decouple, the 2nd LV-T30 pair fires, total engines firing: 4x LV-T30s, 1x LV-T45

At this point, it should be full throttle the rest of the way to orbit

3rd stage: one LV-T30 pair decouples

4th-ish stage: both LV-T30s decouple, followed very shortly thereafter by the LV-T45 decoupling, the next one fires, as do the 2x L-909s above the decoupler

5th stage: LV-T45 decouples, the LV-909 above it fires (so 3 LV-909s going now)

You should be just about to orbit when the LV-909 pair runs out, which leads to stage 6

6th stage: LV-909 pair decouples, leaving just 1 LV-909 to circularize and begin trans-munar injection

7th and final-ish stage: the LV-909 decouples, and the 2two LV-909s above it fire:

These complete the transmunar injection, capture, and landing.

When landed, have your other kerbal get in the free command pod.

And (important!) transfer one of the FL-T200 tanks each to a different FL-T400 tank (since I'm assuming you're doing this without fuel line tech)

You should have enough dV left to get the whole thing to munar orbit, and back to kerbin, if you're cutting it close (or for coolness points), you can decouple the FL-T400 tanks (along with their attached pods, parachute, and engines) from the center FL-T200 stack, that way each rocketbal pilots his own rocket back to Kerbin. You can also have them leave at different times if the rescue kerbal wants to stick around for a few more Munar orbits.

Edited May 8, 2014 by KerikBalm

[linkxsc]

^ a true kerballian work of art. Can u post the .craft for that. I wanna take it for a spin