Ascend from Tylo

[nhnifong]

I've fired my biggest rockets out to Jool, pushing 1000 parts, and I just can't seem to get anything big enough to land on Tylo and return to orbit. Has anyone done this stock? What does the lander look like? I though that if something can land and return to orbit on Kerbin, then it can do it on Tylo, but My lander stages always hit the ground at about 500 m/s. I don't see how I could possibly bring enough fuel to slow down 500 more m/s when my launchers are already 1000 parts.

This was my latest attempt. Sorry I don't have a pic of the lander decoupled from the transfer stage, but you get the picture

[r_rolo1]

By just eyeing the pics, couldn't you maybe change those lateral LVs for aerospikes? That could probably help a little ...

[nhnifong]

Also, is it most efficient to land by burning at full throttle such that you run out of fuel roughly when you get to the ground? This is how I've been attempting to time it. I don't know how much fuel it's really saving me.

[r_rolo1]

Yeah, the best way to land fuel wise ( in RL, might not apply in the game ) in a body with no atmosphere is to go as vertical as possible and burn at full power as close of the ground as possible, the so called suicide burn ( suicide because you will spat as a pancake if you don't burn at the exact time and you have no margin for corrections. Hence it is not used in RL )

Other thing you might consider is to rework your landing stage. I'm seeing two SAS there, that you probably need for the full rocket but that might not be needed for the lander itself. You also have a LV sitting inert in the second stage that you could put to use if you redistributed your fuel tanks ( meaning one less ton in the landing stage, because you could take one of the third stage LVs out ). You might also consider to use drop tanks ( less mass in the lander = less fuel needed )

[nhnifong]

Thanks for the tips.

By drop tanks, do you mean only tanks or tanks with engines which drop, like an asparagus launcher?

[Awaras]

Dude, your first stage rocket is way, WAY inefficient.

The first rule is that with an ideal design, ALL your engines (well, not counting the nuclear ones because they suck on the surface of Kerbin) should fire when you launch.

Basically, you need to build a wide rocket instead of a tall one.

I was able to get this to Jool (about as massive as your ship in orbit):

using this first stage:

The ascent stage is basically just 8 stacks of 4 large fuel tanks with a mainsail engine on the bottom...

Edited October 15, 2012 by Awaras

[UNSC]

I think it's the thinner atmosphere making it difficult to land. While takeoff should be easier.

[r_rolo1]

Thanks for the tips.

By drop tanks, do you mean only tanks or tanks with engines which drop, like an asparagus launcher?

Yeah, pretty much. But with no engines below The RL space shuttle actually used a big one attached to the return veicule, if you recall ...

@ Awaras

True, ideally you want all of your engines firing up at launch. Otherwise they are simply dead weight ...

And BTW are trying to ram any of the Jool moons out of orbit ? That is quite a rocket there

[Awaras]

Yeah, pretty much. But with no engines below The RL space shuttle actually used a big one attached to the return veicule, if you recall ...

@ Awaras

True, ideally you want all of your engines firing up at launch. Otherwise they are simply dead weight ...

And BTW are trying to ram any of the Jool moons out of orbit ? That is quite a rocket there

It is supposed to go there and come back with a bit of fuel left over for unforseen circumstances... I ended up replacing the engines with nuclear ones and it had plenty of fuel.

[nhnifong]

Yeah I guess it is, but I like how it LOOKS like a rocket (actually it looks more like a syscraper). But I'll do whatever it takes to land on Tylo in the KSP world whether it looks like a rocket or not

[Awaras]

Yeah I guess it is, but I like how it LOOKS like a rocket (actually it looks more like a syscraper). But I'll do whatever it takes to land on Tylo in the KSP world whether it looks like a rocket or not

I like to see a rocket look like a rocket too, but with drag implemented the way it is now there is absolutely no penalty for building short, fat rockets. Also, this is the only way I can launch anything large without overloading my computer. If I tried to launch your monster I think my PC would explode...

[r_rolo1]

Well, you can use ( almost ) all of your engines and still have a tall rocket, if you use non-gimballing engines on top stages and leave space for the exhaust to pass for the engines in top It just needs more work in the drawing board ...

[Qumefox]

Yeah when they start modelling aerodynamics to even remotely model drag correctly, most people's designs at the moment will probably become unworkable, and we'll see rocket designs become more 'rocket like'.

[nhnifong]

Do you think using shadows on an offscreen buffer (and computing their area to get a drag coeff) will be the method they choose? It would certainly be more interesting than another weird concoction of rules.

BTW I made a thread about drag in the development board

[Awaras]

Yeah when they start modelling aerodynamics to even remotely model drag correctly, most people's designs at the moment will probably become unworkable, and we'll see rocket designs become more 'rocket like'.

Yeah, but by the time they implement a more realistic drag model they will probably also implement docking and orbital assembly. We are currently forced to launch from the ground ships that would realistically be launched piece by piece and assembled in orbit...

[EndlessWaves]

I don't see how I could possibly bring enough fuel to slow down 500 more m/s when my launchers are already 1000 parts.

The lightest capsule, a 200L fuel tank and aerospike can slow down from 1500m/s to 0m/s.

add two 400L tanks on decouplers on the sides and it'll slow down from 4500m/s

Efficiency savings start at the top. Make the landing and return sections as small as possible for the job and you'll have a much easier time in designing the rest of the rocket.

Edited October 15, 2012 by EndlessWaves

[Qumefox]

Efficiency savings start at the top. Make the landing and return sections as small as possible for the job and you'll have a much easier time in designing the rest of the rocket.

^^ This

This thing I threw together here:

http://kerbalspaceprogram.com/forum/showthread.php/23955-0-17-Quickie-Mk-I-%28Generic-medium-lift-capacity-launcher-orbiter%29

will get to orbit with 1000m/s worth of delta-v left in the bottom stage, and the top orbiter can manage over 8000m/s delta-v (KER's readout on it shows just under 7k m/s, but it's inaccurate because it doesn't account for the loss of mass from shedding the drop tanks) It's fairly no frills, but 9000m/s delta-v will get you to pretty much anywhere in the solar system, and back from most places.

Edited October 15, 2012 by Qumefox

[EndlessWaves]

but 9000m/s delta-v will get you to pretty much anywhere in the solar system, and back from most places.

While it probably has enough range the LV-N is unlikely to have enough thrust to land in Tylo's high gravity.

[Millitron]

I'd actually try to build smaller if I were you nhnifong. For instance, you don't need more than one nuclear engine for each transfer. You need one on your Jool transfer stage, and then one on your return transfer stage, but that's it. Carrying all those nukes is just extra weight making everything unnecessarily large. Likewise, you should stick SRB's on the lander. Their quick, high thrust is great for making that final burn, because like you said, its most efficient to loiter as little as possible.

[nhnifong]

I'd actually try to build smaller if I were you nhnifong. For instance, you don't need more than one nuclear engine for each transfer. You need one on your Jool transfer stage, and then one on your return transfer stage, but that's it. Carrying all those nukes is just extra weight making everything unnecessarily large. Likewise, you should stick SRB's on the lander. Their quick, high thrust is great for making that final burn, because like you said, its most efficient to loiter as little as possible.

Lol, now that you point it out, landing on Tylo with SRBs might be a lot easier than landing on the Mun with SRBs. I don't have to use them as the final landing stage anyways, just the major deceleration stage.

[Qumefox]

My point was more that the less final stage mass you have, the easier time you'll have getting it to where you want it.. Until docking gets implemented and we can assemble larger craft in space, the minimalistic approach usually works the best right now.

[bsalis]

Good to see someone else has found out how hard Tylo is. With all the focus on Eve, not many have noticed it. However, Tylo seems to be the most overlooked celestial body in 0.17 IMO. I have managed to land on it, but didn't have anywhere near the fuel needed to return. Getting back from Lythe in the same craft was easy, and had fuel to spare upon return (well, would have if my navigation wasn't horrific).

Tylo basically the same size and gravity as Kerbin, but no atmosphere! So you need to do burns to get into orbit around it. This is more than an equivalent burn around the Mun in the Kerbin system. Then you also get gravity loss both on descent and ascent. I would guess it's about 3300 m/s total dV each way (the guess being basically Kerbins 4700 less 30% drag loss).

There's no easy way around this. You just need a huge amount of dV, and then have good staging & TWR at the right time of the mission for the descent and ascent. Dare I say, like Eve, you pretty much need a purpose built craft for a return mission.

Edited October 16, 2012 by bsalis

[Markus Reese]

The lander stage itself looks good. I haven't been to tylo yet so not sure the exact atmo and gravity concentration. I do see what I would try changing. Mainly that single goofy looking engine between your half 2m and full 2m tank. That is extra weight and not really sure if it actually has a functional purpose. Second would be those high thrust yet inefficent large engines. If tylo's gravity is less, try running just the efficient engines out there. Also put in the 2m high SI engine in the centre. It gets pretty good thrust in itself and have the outer tanks feed inner instead. Jettison those small outer ones as needed. You probably could even try putting the high efficiency 1m engines on the outer as well. Without atmosphere getting off is easier.

Now since writing that first paragraph, I looked at some info, and assuming gravity on Tylo is similar, I recommend hauling some braking SRBs. I use them on spaceplanes and many other of my rockets for departure. My duna rockets all use them. The instant thrust at low weight is perfect for stopping. Can try fitting them outside of your lander engines to brake. For the launch, in that gap on the inner radius, attach some initial launch srbs to get a high velocity before burning your fuel. Without the atmo problem, get your horizontal velocity up using the srbs as fast as possible. This should allow you the time to use efficient engines to capture a low altitude orbit without having to worry about falling.

With my spaceplanes lack of functioning atm, I will need to hit tylo for a break, sounds like a fun challenge.