Landing on Tylo - DV?

[RocketBlam]

I tried landing on Tylo using a lander based on the published DV necessary, which is about 3070. My lander had two stages and a total of 6300 DV. But by the time I landed, I only had about 1200 DV left in my second stage (after having transferred all fuel out of the spent 1st stage), which wasn't enough to get back to orbit. So... what did I do wrong?

I believe I landed from about 20k feet. It took all engines in both stages to just get it slowed down enough to land.

Was my TWR too low?

Edited March 16, 2014 by RocketBlam

[Woopert]

Not sure, but Kerbal Engineer will list TWR for all of the planets and moons, it's definitely worth checking out!

http://forum.kerbalspaceprogram.com/threads/18230-0-23-Kerbal-Engineer-Redux-v0-6-2-3

[RocketPilot573]

Your Delta-V looks fine to me (should be enough to both and and takeoff. However, you TwR is wayyyyyy to low. Tylo has a gravity of .8 G, so to liftoff you will need at least a Kerbin TwR of 0.8. But that still wont cut it (Tylo is hard), so I recommend at LEAST 1.5 (preferably more). Basically, get the TwR as high as you can manage without losing that Delta-V.

Also, having a very low TwR will actually increase the required Delta-V to land/takeoff (because you'll spend more time and fuel "fighting gravity"), so that's why it seemed that your ship didn't have enough fuel.

[RocketBlam]

Alright, this is my second attempt. DV is a touch higher, but TWR is much higher. And the whole thing weighs a lot more.

[Procyon]

did it make it?

[Tank Buddy]

That's pretty big. I would recommend downsizing because that's gonna be a hellova pain to launch and bring to Jool..

[maccollo]

That's way overpowered if you are concerned with efficiency.

Rule number one for landers: Always use the rockomax 48-7S!

[RocketBlam]

What kind of DV does that have? Remember I need 3000 on the way down and 3000 on the way up, possibly more.

[RocketPilot573]

What kind of DV does that have? Remember I need 3000 on the way down and 3000 on the way up, possibly more.

The 48-7S engines don't have mush ISP (350), however they have 30 thrust and weigh nothing, making them (mathematically) nearly the best engine in the game by far. Just make a tiny asparagus staged lander (no more than 10 tons). It will probably have a TwR of like 2-5, and have unbelievable amounts of Delta-V (for how tiny the rocket is).

And yea, that second lander has great stats, but is indeed really heavy to actually get to Tylo in the first place.

Edited March 15, 2014 by RocketPilot573

[maccollo]

The total delta V is 6680 m/s so it's well within safety margins.

3540 on the first stage with a TWR of 1.54 and 3 at 25% fuel.

3130 on the second stage with a TWR of 1.53.

Craft file: https://dl.dropboxusercontent.com/u/22015656/tyloLander.craft

Like I said, always use the rockomax 48-7S XD

It could probably be slimmed down even further, especially with asparagus staging, but I prefer the simplicity of serial staging

Edited March 15, 2014 by maccollo

[StrandedonEarth]

My advice is to leave the science units on the ground. Pull the experiments from them on EVA and store them in your pod. The lander can is also lighter than the Mk1. Lighter is better!

This was my rescue rover. The ascent stage is just the FL-T200 tank in the middle with a 48-7S. Command seats are as light as you can go, and then EVA over to the Kerbin return vehicle. While the rover itself had enough dV to land itself, I used the nuclear transfer stage with a few whiffs (an FL-T800's worth) of leftover fuel for the initial deorbit and descent for even more margin. I had 1 LVT-45 descent engine at each end and dropped the extra tanks as they emptied. Tons of TWR for emergency power.

[RocketBlam]

Well those are great numbers, and it's a nice lander, but it doesn't have any science gear on it.

I'll see if I can get the weight down on mine. I took it into orbit, and discovered I had forgotten a docking port. So I decided to take it on a shakedown cruise to Minmus, which is good, because I discovered I had also forgotten batteries.

[RocketBlam]

Don't you have to bring back the materials bay and the goo canister? Or transmit them for less science?

[RocketPilot573]

This was about 300 m/s short of making orbit, the Kerbals had to bail and use their jetpacks. But close enough, right?

Note that this was only single staged, so making it have two stages should fix the fuel problem (just remember to put the seats on the center tank, jettisoning the pilots is not safety first!).

Edited March 15, 2014 by RocketPilot573

[StrandedonEarth]

Don't you have to bring back the materials bay and the goo canister? Or transmit them for less science?

Nope. EVA your kerbal, stand close to the experiment (material bay, goo can, etc) and right-click on it. Then click "remove experiment" or whatever it says. You can then carry the experiments around and store them in your command pod. You can also repair broken landing gear and wheels, or repack 'chutes this way.

Edit: The only downside I've found from abandoning my ascent vehicles is not getting science for "Recovering a vehicle returned from (way the heck out there)"

Edited March 15, 2014 by StrandedonEarth

[maccollo]

Well those are great numbers, and it's a nice lander, but it doesn't have any science gear on it.

Could add 4 goo canisters and 2 science bays to the first stage and it would still have 3100 m/s, which should be enough to land if you're good enough =P

[RocketBlam]

OK, here's my third attempt. It's a bit ungainly, but it weighs only about 1/3rd what the other one does. I decided to leave batteries, antenna and reaction wheel off. It handles like a pig without the reaction wheel, but... the other one handled like a pig WITH one.

[Woopert]

Going to try and whip up something for this as well!

I've tried Eve landers but Tylo should be easier because of the lack of an atmosphere (well, there might be some trace gases if you use your imagination ).

It's nice to see people have so much patience with the game, Tylo is quite an unforgiving place.

[maccollo]

It could be made lighter still. My lander only weighs 12.5 tons and it has more delta V, even with the Science stuff added.

Keep in mind that just the RCS you brought weighs more than all of the engines in my lander. That's why the 48-7S is so good. It allows you to get very a good mass fraction out of your rocket.

Also, if you make your lander light and compact you don't need RCS or reaction wheels. The pod reaction wheel + engine gimbals gives enough control authority.

BTW the 48-7S has twice the gimbal range of the LV909, yet another reason why the 909 is almost completely obsolete =P

Edited March 16, 2014 by maccollo

[StrandedonEarth]

Again, you can leave the science gear on the surface, just "take data" first (since 0.23, that is). More TWR is always good for descent, for those panic situations when you find the ground rushing up at you. Not sure how you're going to drop those top tanks