Need Some advice on my rocket

[DragonHalo99]

OK so I have 3 contract's 2 for vip's and 1 for 2 tourists. total value of the contracts all together is 188500. Anyways the 2 tourists and 1 vip want to go to the mun for a flyby and then orbit and back and the other vip wants to flyby minmus. problem without kerbal engineer I'm not sure exactly what delta V I need and If I have the parts unlocked to do this mission. I am playing the 1.2 prerelease. Here is the rocket design and the next image is the researched parts i have available.

http://imgur.com/a/XqSim

The idea was I could use the terrier's for orbital manuevers then when they where spent eject them and use the poodle. once in orbit I ended up activating the poodle early too make orbit and then I decided that the mission wouldn't work and reverted to the vab. The mainsail im using as the sustainer is at 75% thrust.

Edited October 11, 2016 by DragonHalo99

[Sresk]

The mun to minmus is weird. Sometimes I've done it with less than 200 dv to leave mun orbit and get a minmus encounter. But if they aren't lined up right it can take 800+... but if your not playing with life support and your willing to be patient you don't need much.

However I will say it's WAY easier to go from minmus to the mun than the other way.

[Snark]

Moving to Gameplay Questions.

Some advice on the rocket:

• Run the Mainsail at full power, there's no reason to thrust-limit it.
• Do you really need the Terriers?  If the Poodle has enough oomph, you can just use that and ditch the Terriers, saving a couple of tons of dead weight (four engines at half-a-ton each).  Have the Poodle drain those radial tanks, then drop 'em when they're empty.
• You have way, way, way too much monoprop on that thing, and far too many RCS thrusters.  For that matter... I don't even see any docking ports, why do you carry any RCS or monoprop at all?  Get rid of 'em all and you can save a whole bunch of weight.

[DragonHalo99]

rcs has saved me in the past so i usually bring extra along in case I run out of fuel right as I need to slow down for a return. I will give these changes a shot.

[DragonHalo99]

Ok I got rid of the rcs all together and the terrier's. I also dropped the fl-t200's for the fl-t400. question though when I enable fuel crossfeed for the decouplers why is it feeding into one of the side tanks from the main tank on one of the radial tanks? http://imgur.com/a/Evkn3

Edited October 11, 2016 by DragonHalo99

[Nich]

I hate to say it but you need to learn orbital mechanics.  That is a nicely designed rocket and should have enough dv to land on both the Mun and Minimus.

Sorry if this is insulting I have a hard time understanding how you could design a rocket that well (excluding RCS spam) and not know how to fly by Mun and Minimus.

I will admit the hardest thing about this mission is that it is really only possible twice every 50 days when the Mun and minimus are in perfect position.  Alternatively you could capture and orbit the Mun and wait for the transfer window.  I think it is about 150 degrees but I dont do that transfer enough to know for sure.  Alex Moons tools says 158 degrees (https://alexmoon.github.io/ksp/#/Mun/20/Minmus/20/false/ballistic/false/1/1) Learn to play with the next orbit button.  Left click your manoviour node and hit the plus.  So what you do is:

1. orbit the mun.  

2. set a manivour node exiting prograde that just meets up with minimus's orbit.

3. Hit the plus button until intercepts are close (you will have to adjust the node to account for the muns rotation as you advance orbits)

If this is not clear I have been looking to make advanced tutorial videos and this would probably be a good example

[Blaarkies]

1 hour ago, DragonHalo99 said:

rcs has saved me in the past so i usually bring extra along in case I run out of fuel right as I need to slow down for a return. I will give these changes a shot.

That is like bringing a bicycle along on a week long road trip. Sure if you run out of fuel, the bicycle could help...but bringing 10 liters of extra fuel in a jerrycan would take you much further than the bicycle.

If you need some extra dv just-in-case, than add a LFO tank, then lock it. Once in an emergency, unlock it and go much further than RCS would ever have.

Even when this happens after you dropped your engines, you would still get more results from an Ant engine, which weights far less

[Aegolius13]

1 hour ago, DragonHalo99 said:

rcs has saved me in the past so i usually bring extra along in case I run out of fuel right as I need to slow down for a return. I will give these changes a shot.

If you're carrying some anyway for maneuvers, and you happen to need it as impromptu fuel, that makes some sense.  But if you're not planning on doing anything RCS-ish with it, you'll get much better mileage dedicating that weight to regular fuel for your Poodle.  Even if you want to turn off the tank and set it aside as emergency fuel, you'll still do better.  

Not sure if you've familiarized yourself with specific impulse at this point, but it's a number that basically quantifies a given engine's fuel efficiency.  The Poodle is the best of all liquid fuel / oxygen engines, at 350.  The RCS thruster block's specific impulse is 240, meaning it takes a lot more fuel to do the same weight.  And it's actually worse than just the specific impulse number would tell you, since the thrusters add weight and atmospheric drag.  (Also, it's a small difference, but monopropellant tanks have a bit more dry weight than rocket fuel tanks).  

I personally hate monopropellant (can you tell?) and avoid outright whenever possible.  It's occasionally handy if you can just use the built-in monoprop in a command pod to run some thrusters.  But it's a rare event when you'll need more than that in a typical ship.  In the rare cases where you need enough thruster-ing to require a lot of fuel, it's probably easier to go with the Vernors, which run on rocket fuel and deliver better power and efficiency.  When you don't need any monopropellant at all (which is pretty common), you can even drain the command pods to save a little cost and weight.  

[DragonHalo99]

1 hour ago, Nich said:

I hate to say it but you need to learn orbital mechanics.  That is a nicely designed rocket and should have enough dv to land on both the Mun and Minimus.

Sorry if this is insulting I have a hard time understanding how you could design a rocket that well (excluding RCS spam) and not know how to fly by Mun and Minimus.

I will admit the hardest thing about this mission is that it is really only possible twice every 50 days when the Mun and minimus are in perfect position.  Alternatively you could capture and orbit the Mun and wait for the transfer window.  I think it is about 150 degrees but I dont do that transfer enough to know for sure.  Alex Moons tools says 158 degrees (https://alexmoon.github.io/ksp/#/Mun/20/Minmus/20/false/ballistic/false/1/1) Learn to play with the next orbit button.  Left click your manoviour node and hit the plus.  So what you do is:

1. orbit the mun.  

2. set a manivour node exiting prograde that just meets up with minimus's orbit.

3. Hit the plus button until intercepts are close (you will have to adjust the node to account for the muns rotation as you advance orbits)

If this is not clear I have been looking to make advanced tutorial videos and this would probably be a good example

ok I pulled it off and got it after making more adjustments and changes to the rocket. Turns out you where right I had way more delta V than i needed for the trip. I flew by minmus first for the first contract then encountered and slowed down just enough to orbit the mun then immediatly sped up to escape then slow down to renter kerbin. http://imgur.com/a/kdfr6.

[DragonHalo99]

58 minutes ago, Aegolius13 said:

If you're carrying some anyway for maneuvers, and you happen to need it as impromptu fuel, that makes some sense.  But if you're not planning on doing anything RCS-ish with it, you'll get much better mileage dedicating that weight to regular fuel for your Poodle.  Even if you want to turn off the tank and set it aside as emergency fuel, you'll still do better.  

Not sure if you've familiarized yourself with specific impulse at this point, but it's a number that basically quantifies a given engine's fuel efficiency.  The Poodle is the best of all liquid fuel / oxygen engines, at 350.  The RCS thruster block's specific impulse is 240, meaning it takes a lot more fuel to do the same weight.  And it's actually worse than just the specific impulse number would tell you, since the thrusters add weight and atmospheric drag.  (Also, it's a small difference, but monopropellant tanks have a bit more dry weight than rocket fuel tanks).  

I personally hate monopropellant (can you tell?) and avoid outright whenever possible.  It's occasionally handy if you can just use the built-in monoprop in a command pod to run some thrusters.  But it's a rare event when you'll need more than that in a typical ship.  In the rare cases where you need enough thruster-ing to require a lot of fuel, it's probably easier to go with the Vernors, which run on rocket fuel and deliver better power and efficiency.  When you don't need any monopropellant at all (which is pretty common), you can even drain the command pods to save a little cost and weight.  

 

1 hour ago, Blaarkies said:

That is like bringing a bicycle along on a week long road trip. Sure if you run out of fuel, the bicycle could help...but bringing 10 liters of extra fuel in a jerrycan would take you much further than the bicycle.

If you need some extra dv just-in-case, than add a LFO tank, then lock it. Once in an emergency, unlock it and go much further than RCS would ever have.

Even when this happens after you dropped your engines, you would still get more results from an Ant engine, which weights far less

Actually come to think of it I'm not sure why I threw the rcs on there in the first place. I drive an 18 wheeler so I am kinda tired. just got home earlier for hometime.

Maybe i should actually do a proper mun landing this time. I have landed on the mun a few times but I blew up the engine and landing gear the few times I tried so I don't count them as succesfull.

[Blaarkies]

10 minutes ago, DragonHalo99 said:

Actually come to think of it I'm not sure why I threw the rcs on there in the first place. I drive an 18 wheeler so I am kinda tired. just got home earlier for hometime.

Maybe i should actually do a proper mun landing this time. I have landed on the mun a few times but I blew up the engine and landing gear the few times I tried so I don't count them as succesfull.

No worries, the only reason i said it was...because i have did the exact same thing many times before. Until i took a step back and actually calculated the "efficiency" of my backup system. Yeah, i was shocked 

However, if you only use a capsule(+heatshield for re-entry)...then by adding a single Linear-RCS thrust port on that capsule, and filling the capsules MonoProp leads to a totally viable backup system. There is no extra dry tanks being added this way(the capsule is already the dry tank), so filling it up is probably very mass efficient.

[DragonHalo99]

woot I managed to pull off a mun landing as well and several contracts I got my R & D maxed out and my vab as well. only upgrade left is the sph. Now I have to rendevous 2 vessel's in orbit of the mun. Should be easy peasy once I get some sleep. I also need to get a geostationary satellite network up at some point......

[Nich]

8 hours ago, DragonHalo99 said:

 

Actually come to think of it I'm not sure why I threw the rcs on there in the first place. I drive an 18 wheeler so I am kinda tired. just got home earlier for hometime.

Maybe i should actually do a proper mun landing this time. I have landed on the mun a few times but I blew up the engine and landing gear the few times I tried so I don't count them as succesfull.

if you already know how to get to minimus (that is the hard part) try landing there first.  Factor of 10 easier between the lower gravity and smoother terrain. Make sure to use F5/F9 to save reload.  It took me at least 10 attempts my first time landing on the Mun.

[Kerbal101]

I think git version of KER supports 1.2pre. At least this is the version Roverdude was using in his recent Twitch stream.