12K Delta V to Minmus? Need a career stock rocket

[bighara]

The online calculator show 11480 m/s (round up to 12K) for a round trip to Minmus. I can't get anywhere near that in my career game builds. I've unlock a fair bit of tech, but I'm running out of gas trying to get back with my guy and my science.

[Claw]

You don't need quite that much. You can leave out most of the fuel required to go return from Minmus to Kerbin because Kerbin lets you aerobrake.

If you take a look at the map below, it takes about 4550 m/s to make Kerbin orbit, then another 920 to get to Minmus. Then 320 (240 + 80) to catch orbit and land. You'll need roughly 320 dV to get off of Minmus and break Minmus orbit, to head back to Kerbin.

So in total: 4550 + 920 + 320 + 320 = 6110 m/s.

So you don't need the 920 m/s to return, nor do you need the 4550 m/s to get from Low Kerbin Orbit back to land on Kerbin.

[sal_vager]

Can you get from Kerbin to the Mun and back? That craft you used can get you to Minmus and back no problem.

[Claw]

If you are running out of fuel, perhaps you need to attempt escaping Minmus orbit in a different direction. Where you leave Minmus' orbit can impact the amount of return dV that you need. You want to stay in a fairly low Minmus orbit (the lower the better, but look out for terrain of course). Once you're in orbit, try setting up a maneuver node and just pull on the prograde marker for a couple hundred dV. Then drag the maneuver node forward/backward around the orbit by grabbing the white ring. Eventually you'll find a place where you can eject from Minmus' orbit and head back to Kerbin with a small amount of dV. That point should be roughly on a spot where your orbit is between Minmus and Kerbin.

Aim to arrive around Kerbin with a PE around 30-35 km. That will allow you to burn off some speed when you return by aerobraking.

If you aerobrake too high, you'll just have to wait another orbit to finish burning off speed. If you aerobrake too low, be careful not to rip off the parachutes.

[Sirrobert]

There is no way you need that much to get to Minmus.

Sounds like you count the deltaV needed to take off from Kerbin twice. But you don't need to use any fuel to land on Kerbin, since you can let your parachutes do that.

What calculator told you this?

[G'th]

^ I'm certain thats the case. Shave off that extra 4500 dV and you end up at ~6k, which is about right depending on payload.

Granted, it can be more if you want to account for possible course corrections to and from and the possibility of establishing LKO again (Which takes less coming from space than it does from the surface). But I don't think the OP plans on any of that.

[randomness5555]

Minmus!? Gonna put it simply, you probably put in MOHO by accident, because you do need about 10-12K deltav to get to moho depending on various thingamawhosits. Minmus probably uses less than the mun due to low gravity.

[Claw]

There is no way you need that much to get to Minmus.

Sounds like you count the deltaV needed to take off from Kerbin twice. But you don't need to use any fuel to land on Kerbin, since you can let your parachutes do that.

What calculator told you this?

^ I'm certain thats the case. Shave off that extra 4500 dV and you end up at ~6k' date=' which is about right depending on payload.

Granted, it can be more if you want to account for possible course corrections to and from and the possibility of establishing LKO again (Which takes less coming from space than it does from the surface). But I don't think the OP plans on any of that.[/quote']

Minmus!? Gonna put it simply, you probably put in MOHO by accident, because you do need about 10-12K deltav to get to moho depending on various thingamawhosits. Minmus probably uses less than the mun due to low gravity.

Yes, look at the dV map. If you add it all up: 4550 + 920 + 80 + 240 + 240 + 80 + 920 + 4550 = 11580 m/s. That's only 100 m/s over what the OP states. Which is probably because whatever calculator was used assumes 4500 m/s off of Kerbin instead of 4550 m/s in the chart above.

So whatever calculator probably did a full round trip with no aerobraking. As you all said, the last 920 + 4550 m/s isn't necessary.

[Starwhip]

My Minmus rockets are always smaller than my Mun rockets, because of Minmus' lower gravity. One FL-T200 in tandem with a '909 is good enough for a 1-man lander with science payload to land, take off, and return.

[SRV Ron]

This did Minmus and return with plenty of fuel left. Straight pancake staging, No onion, no asparagus, no SRBs. Certainly, no 12k of Delta V.

[SRV Ron]

The aerobraking maneuver you want for an efficient return from Minmus or Mun.

Note, you want to do an escape retro to the moon's rotation around Kerbal.

[NERVAfan]

You don't need quite that much. You can leave out most of the fuel required to go return from Minmus to Kerbin because Kerbin lets you aerobrake.

If you take a look at the map below, it takes about 4550 m/s to make Kerbin orbit, then another 920 to get to Minmus. Then 320 (240 + 80) to catch orbit and land. You'll need roughly 320 dV to get off of Minmus and break Minmus orbit, to head back to Kerbin.

So in total: 4550 + 920 + 320 + 320 = 6110 m/s.

So you don't need the 920 m/s to return, nor do you need the 4550 m/s to get from Low Kerbin Orbit back to land on Kerbin.

True. But I would bring quite a bit more than that to allow in inefficiencies in landing and return... but not 12000, more like 8000.

[Pecan]

Design backwards:

Your lander/return stage needs to launch from Minmus, orbit and escape its SOI: 180 + 70 + 90 = 340m/s. From there it can aerobrake to landing.

Your transfer stage needs to get the above to Minmus and into orbit: 680 + 180 + 70 + 90 + 70 = 1,090m/s + above = 1,430m/s - give yourself 10% for comfort = 1,573m/s

Plus launch: 4,500m/s + above = 6,073m/s.

Even if you don't want to aerobrake completely and want a good margin you 'only' need to double 1,430 and give yourself 10% = 3,146m/s.

That should still be a small, light payload you can easily launch (for a grand total of 7,646m/s) and which has plenty of spare deltaV.

That is, I think, the plan I used for Long Tom:

Javascript is disabled. View full album

That and Fat Sally are also good for Mun.

[MisterInSayne]

Minmus and back? easy with the very basic rocket parts.

[technion]

This is the problem with doing this much maths and calculations. If you've been to the Mun, you know the size of the rocket you need to get there.

And you can see when you do that, that just a bit more burning will get you there. And you know how easy it is to get home, and that you don't need 4k dv to land on Kerbin.

A certain level of engineering is required on larger missions, but OP, I'd urge you just to play the game. If you've been to the Mun, try taking that exact same rocket for a Minmus flyby. If you make it with even a bit of fuel left, you can probably then land.

[[email protected]]

You only need 12k of Delta-V if you plan on landing in every single biome in one trip. Even then thats likely overkill.

[Claw]

True. But I would bring quite a bit more than that to allow in inefficiencies in landing and return... but not 12000, more like 8000.

I won't argue with that, but if the OP is using a calculator to figure out dV requirements, I was trying to illustrate where the 11.5 km/s came from. The OP's 12,000 m/s is not from padding, but from the calculator totaling up all the dV required, to include re-establishing orbit around Kerbin and flying back down (non-aerobrake).

[MarvinKitFox]

Your calculator is 100% correct, you DO need 12000 delta-v to go from Kerbin surface to land on MinMus, and return to Kerbin surface.

Fortunately, Kerbin has an atmosphere that will supply the last 4550+950 = 5500 for you, via aerobraking.

That leaves you with 12000-5500 = 6500, a very achievable goal.

[bighara]

Thanks for the help! I made it there and back finally. Unfortunately, my later Mun mission wasted too much fuel getting upright after tipping over on landing. I collected the science and got off the Munar surface, but Jebidiah is trapped in a Kerbin orbit now. He transmitted what he could (Yay for photovoltaic panels!), but I'm going to try an unmanned rocket to save him.

[Kerba Fett]

A couple of other fuel saving tips are to use jet engines to get you up to 20 km before you start using rocket fuel and don't match inclination with Minmus. Use the normal adjust to move your path up or down to intersect minmus's orbit and do a correction burn once you're on the way. It will use less than the 200 m/s of dV you'd use to match inclination.

[SRV Ron]

A early Career design, replace the lander stage engine with an LV-909 and the early lander legs, that will easily do Minmus slightly less efficient then the one pictured;

If you keep running short on fuel, double up on the SRBs as is done with this design tweaked to 80%. You will arrive at Minmus with fuel to spare for landing.

[Mipe]

LV-909

On the picture, it looks kind of small for a stormstro- er, LV-909... Surely you mean 48-7S?

[Sirrobert]

On the picture, it looks kind of small for a stormstro- er, LV-909... Surely you mean 48-7S?

That's why he said 'replace with the LV 909'

becuase you don't have the 48-7S yet early on

[Basketcase]

I just did a mission trying to use the least amount of fuel I could. I still ended up with way too much fuel left over.

Here is the gallery of the trip:

http://imgur.com/a/viCHF#0

[magnemoe]

A early Career design, replace the lander stage engine with an LV-909 and the early lander legs, that will easily do Minmus slightly less efficient then the one pictured;

http://i.imgur.com/QZLCvRM.jpg

I say the rocket is overkill, lander with a 909, gives 2600 m/s, Upper stage gives 2400 m/s, add two of the SRB to it and they add another 1400 m/s, you will have to circulate with the lander but should have around 2km/s left to get to minmus, land jump around a couple of times and land.

I have used the exact same booster design but that has included material labs and goo containers on the lander increasing the payload.