Tylo landing And accent Deltav? And TWR

[Dooz]

so im gonna do a Tylo Mission And and Im bit curious Of What Kind of Delta v i need in order to Land and Ascend back into orbit And a TWR Any tips.

Edited February 28, 2014 by Dooz

[astropapi1]

Map says it's about 3070 for landing, and another 3070 for launching. Also, Tylo is similar to Kerbin, so you can test your lander at the launchpad.

[MoonMan22]

This map is similar to the one astro posted but just a bit more updated and detailed.

[Alchemist]

The orbital speed is slightly above 2 km/s, gravity is about 0.7g, everything else depends on your playstyle.

You can try simulating Tylo landing by starting in 100 km Kerbin orbit, getting to 0 surface velocity at 70 km altitude then getting back to 100 km orbit (that requires slightly more, but if your craft pulls it, it gives you some margin of error you'll need.

[capi3101]

This one says 2270 down and 2270 back up. To my knowledge, this is the most up to date version of the KSP delta-V map out there.

Surface gravity is 7.85 m/s² according to the wiki, about 80% that of Kerbin's. A lander that can launch off of Kerbin should be capable of performing the mission.

[Tank Buddy]

All of responses seem to have the right idea; when viewing a Delta V map, the last value is the DV to land/take off (The values are identical on bodies w/o and atmosphere.) I would go with 3070 m/s to be safe, and you could always put fuel back into your transfer stage if you have extra fuel.

To find the TWR of your ship, multiply the mass of the ship by the planet's surface gravity (7.85 m/s on tylo), then divide your ship's total mass by that values.

[Geschosskopf]

To find the TWR of your ship, multiply the mass of the ship by the planet's surface gravity (7.85 m/s on tylo), then divide your ship's total mass by that values.

Also realize that a Tylo lander doesn't need to START the descent with a TWR > 1, provided it's not too much lower. Due to having to burn a vast amount of fuel during the descent, your ship will be considerably lighter by the time it reaches the ground, and this might be enough to get the TWR above 1 by then.

For this and a few other reasons, Tylo landings depend a lot on your descent profile. A ship capable of landing safely from a given starting altitude and descent angle will splatter using different parameters. So when testing a design, if it ALMOST makes it with 1 set of starting conditions, tweak the starting conditions a bit and try again. You might find a way that works instead of having to redesign the ship.

[tavert]

A delta-V map only shows a single number for landing and takeoff. This is an extreme simplification and tries to show generic average numbers, so is not all that useful for detailed design.

For landing and takeoff from an airless body, the delta-V cost depends on your TWR, specific impulse, and trajectory. For ideal minimum values assuming the best possible trajectory, see data here http://forum.kerbalspaceprogram.com/threads/39812-Landing-and-Takeoff-Delta-V-vs-TWR-and-specific-impulse

[wasmic]

Landing and take-off should be about 2500 m/s each, if you're a proficient pilot. It also depends on the TWR - the lower your TWR, the more delta-v you'll need, so if you TWR is quite low, you should pack about 3000 m/s for each (landing and ascent).

[The Destroyer]

Accent Deltav? I didn't know Tylo had an Accent!

[Nao]

so im gonna do a Tylo Mission And and Im bit curious Of What Kind of Delta v i need in order to Land and Ascend back into orbit And a TWR Any tips.

RUN Probe! RUN for your life, from my claws!

(On a less off topic note, the most efficient landings (and ascents) are done as close to the surface as possible BUT, Tylo can have a nasty surprise for you as it has several high areas (up to 11km), at 1-2km/s speed they can come up faster than your craft can correct. Also hovering at 0,7g's make quite a drain on fuel so make sure your craft is prepared for quick, not 100% perfect landings)

GL with setting that fast expo on Tylo Probe ... it will be right on time for my 9pool speed!

Edited February 28, 2014 by Nao

[SSSPutnik]

For Tylo, 5800ms of deltaV or more is advisable. (You can use less, but often this involves getting out and pushing).

A start TWR of 1 or higher is advisable. You can do it with less but it gets harder fast.

A start TWR of around 2 is most efficient for maximum payload %

This ship will land and return EASILY with a lot of spare deltaV. 0.23 completely stock.

http://forum.kerbalspaceprogram.com/threads/66957-6730-dV-stock-Tylo-Lander-Gravstar

Edited February 28, 2014 by SSSPutnik

[technion]

The perfect descent involves an absolutely perfect suicide burn - which is incredibly unlikely. More likely, you'll slow right down a few hundred meters up, and burn stacks of fuel trying to land softly. I've built a variety of different Tylo models and it always takes a lot to land, with a fairly small amount of power to ascent.

[SSSPutnik]

You can if you are very brave, make an almost horizontal landing from 8-10km braking horizontally. But it's pretty tricky. Very efficient though.

[Dooz]

Thanks guys i will pack about 5100km Deltav for the landing and accent now time the figure out how to pack it all up but have a TWR.

[SSSPutnik]

5100 not enough really...

[Jean Deaux]

As it happens, I've been whittling away at Tylo for a while now myself and am "just" getting to the point I can land on it. Using MJ to assist with effeciency, I'm dropping a rover with a dropship having a 1:1 TWR at Tylo and I've got enough fuel for just over 4k dV (from orbit). So if you're dropping manually, you're definitely going to want 5k and up just to land.

[tavert]

A start TWR of around 2 is most efficient for maximum payload %

Depends what type of engine you're using:

You can do better by splitting things up into multiple stages, that changes the optimal TWR story a little bit but is harder to plot in a general way.

For single-stage landers if you want to maximize payload fraction, I put together a fancy tool for that here http://forum.kerbalspaceprogram.com/threads/61659-Wolfram-Web-App-Optimal-Single-stage-Lander-Design-Tool, you may or may not find it useful.

[Xavven]

I overbuilt my Tylo lander a bit -- 3600 dV for the landing and a separate ascent stage with 3100 dV. I actually like having a TWR between 2 and 3 for the landing stage so I ended up using 4 aerospikes. I probably could have reduced that to 2 and been fine, though. There are two reasons I overbuild my landers: One, I don't like losing Kerbals; and two, I'm 100% stock (no mechjeb with perfect suicide burns). With 3600 dV coming in from 80,000m orbit, I was running on fumes by the time I made contact.

[undercoveryankee]

80km is a pretty high start for a body with no atmosphere. If your transfer stage can lower orbit and circularize around 15km, that might buy you another 100–200 m/s to use on the descent stage.

[SSSPutnik]

Xavven can you post your craft file or a pic?

@tavert, aware of that graph, I tend to use the 48-7S which must be why I remembered 2. I'll check your calculator out!

[Kasuha]

80km is a pretty high start for a body with no atmosphere. If your transfer stage can lower orbit and circularize around 15km, that might buy you another 100–200 m/s to use on the descent stage.

Definitely, horizontal landing is very useful thing to learn, especially on Tylo. I'd not circularize though, just put the periapsis to some 10 km and burned through it until all my horizontal speed is gone.

[Geschosskopf]

Definitely, horizontal landing is very useful thing to learn, especially on Tylo. I'd not circularize though, just put the periapsis to some 10 km and burned through it until all my horizontal speed is gone.

I find this is a very good thing if you don't particularly care where you land, because it's hard to pick your spot. At least for me. So like if all you want to do is land, plant a flag, grab some science, and leave, this is fine. But if you want to land near something already on the ground, it's more problematic.

[Pecan]

Depends what type of engine you're using:

tavert! You're active in the normal forum again! I love your charts (because they're real data, not conjecture) but thought you'd gone lurker.

[technion]

I'm 100% stock (no mechjeb with perfect suicide burns). .

Tylo is one of those places where it really is very difficult to land stock. Planning a suicide burn when you have no idea where "5000m altitude" means "5000m above surface" or "you're about to hit the surface" is extremely luck based.