[Help Needed] Looking for a reusable Tylo lander!

[thereaverofdarkness]

I am planning a very elaborate Jool mission and I've run upon a hitch: I need a lander design that can carry a Kerbal and full science array to the surface of Tylo and back to orbit to dock with an orbiting station where it can refuel and deposit science, then go back down again--until all biomes have been explored. The most important part of the design (other than just straight up being capable) is for it to be reasonably easy to land so I don't have to retry the landing eighteen times to avoid crashing or wasting excess fuel. I am skilled enough to perform either extended burns or suicide burns, efficient trajectory landings from low orbit, apoapsis sailing, and basic flight adjustments on the fly, but I fly by the seat of my pants--no piloting mods, no MechJeb, no Kerbal Engineer.

I've gone through several ideas and one by one I've failed to meet my minimum requirements. Here's a summary of my best creations so far:

1.) With LV-N engines, 8000+ dV and with a TWR of over 2 when empty. Problem: it seems to not have enough dV due to the very long burn time required to decelerate. It is also just very time consuming to fly, and can't land very easily until its fuel is too low to take off again.

2.) With a Skipper engine, large fuel section, high TWR and over 5000 dV. Problem: doesn't seem possible to get enough dV, no matter the TWR, with conventional rockets and single stage, not even if it's prohibitively large.

3.) With LV-909s and extra drop-tanks, which can be attached at station and dropped off during landing- gets some 7000 dV. Problem: pretty slow to decelerate, runs even lower on fuel than the LV-N design by the time it reaches the surface.

I'm thinking the extra drop tanks is a good idea because it allows the rocket to gain some of the benefit of a two-stage rocket. Perhaps also I could put engines on the drop tanks to improve TWR during the first stage? I can't think of a way to get them on such that the fuel tanks can be docked with and the engines will fire in a balanced manner. Let me know what you guys come up with, or just how impossible you think this is!

[luizopiloto]

try Aerospikes

[thereaverofdarkness]

Not a bad idea, though their TWR is only marginally better than the LV-909 and Isp is the same.

[luizopiloto]

or maybe an 49-7S cluster...

[thereaverofdarkness]

A very large fuel section increases efficiency by greatly shrinking the payload fraction, but the dV gain as you increase fuel percentage comes with a diminishing return. You max your single stage dV too low for it to work. The only way I can see conventional engines working is if I can figure out a way to make a reusable two-stage craft--and it'll help a lot if the larger stage has more thrust while the smaller can conserve engine mass. I'm not worried about expenses, but structural integrity is a concern. I just don't see a way to do this.

[Cupcake...]

This might do the trick...

http://forum.kerbalspaceprogram.com/threads/109736-Quite-possibly-everything-you-could-ever-want-from-a-dropship-lander-Oh-and-it-does-Tylo-too!

Cupcake...

[Majorjim!]

This might do the trick...

http://forum.kerbalspaceprogram.com/threads/109736-Quite-possibly-everything-you-could-ever-want-from-a-dropship-lander-Oh-and-it-does-Tylo-too!

Cupcake...

Yup, I would go with Cupcakes landers. His SSTOs are the most capable on these forums.

[thereaverofdarkness]

Am I reading this wrong? It seems like your Gecko lander has under 4200 dV. I don't see how it's possible to land it on Tylo and take off again.

[Cupcake...]

Am I reading this wrong? It seems like your Gecko lander has under 4200 dV. I don't see how it's possible to land it on Tylo and take off again.

I'm not sure how you arrived at 4200 m/s. I got my abacus out and double checked the figures, it puts out 5345 m/s with drop tanks (or around 5200 without) and has a T/W ratio on Tylo of 1.12 fully fueled.

Anyway, let me know if it works for you. I'd recommend holding the mothership at a low orbit (around 15k) and having a small RCS tug on stand-bye to retrieve the lander if you run out of fuel during rendezvous. Good luck!

Cupcake..

[thereaverofdarkness]

I'm not going to use it, it's beautiful but too clipped and angled for my tastes. I find it difficult to work with.

I learned a valuable lesson from your example, however, and I believe I am on the way to solving my problem! I realize now that the moderate efficiency engines with high TWR are actually MUCH better for this than efficient engines. I can significantly decrease my dry fraction by switching to 48-7S engines, and I should be able to make a lander under twice the size of your Gecko that can carry two goo canisters and two materials bays, which will have at least 6000 dV, along with high TWR and good control. I'll let you know here how it turns out.

The way I calculated the dV was with Strout's dV calculator ( http://www.strout.net/info/science/delta-v/ ), I plugged in the hangar listed mass for starting, and subtracted the fuel mass based on the fuel listed in the readout on the launchpad. I checked my numbers a few times, I don't think I messed up on my fuel mass calculation. Maybe I missed something else important. Oh well.

[Rune]

I'm not going to use it, it's beautiful but too clipped and angled for my tastes. I find it difficult to work with.

I learned a valuable lesson from your example, however, and I believe I am on the way to solving my problem! I realize now that the moderate efficiency engines with high TWR are actually MUCH better for this than efficient engines. I can significantly decrease my dry fraction by switching to 48-7S engines, and I should be able to make a lander under twice the size of your Gecko that can carry two goo canisters and two materials bays, which will have at least 6000 dV, along with high TWR and good control. I'll let you know here how it turns out.

The way I calculated the dV was with Strout's dV calculator ( http://www.strout.net/info/science/delta-v/ ), I plugged in the hangar listed mass for starting, and subtracted the fuel mass based on the fuel listed in the readout on the launchpad. I checked my numbers a few times, I don't think I messed up on my fuel mass calculation. Maybe I missed something else important. Oh well.

Oohh, you are a sciency type of kerbal. My favourite kind! And I see you already learned it yourself, but that's indeed the main lesson to draw from this thread: TWR matters! That, and that 48-7S are completely OP xD

SSTOx2 (down, then up) in Tylo can also be done with less fuel consumption, but more starting mass, using nuclear engines. But mind you, you have to start the burn with TWR a hair under one (which means a long careful reverse-gravity turn trajectory). Pretty much the only other sane option.

Rune. To actually make it easier to pilot, you have to go with two stages and >7km/s, or ISRU. Care for mods?

[Cupcake...]

I'm not going to use it, it's beautiful but too clipped and angled for my tastes. I find it difficult to work with.

I learned a valuable lesson from your example, however, and I believe I am on the way to solving my problem! I realize now that the moderate efficiency engines with high TWR are actually MUCH better for this than efficient engines. I can significantly decrease my dry fraction by switching to 48-7S engines, and I should be able to make a lander under twice the size of your Gecko that can carry two goo canisters and two materials bays, which will have at least 6000 dV, along with high TWR and good control. I'll let you know here how it turns out.

The way I calculated the dV was with Strout's dV calculator ( http://www.strout.net/info/science/delta-v/ ), I plugged in the hangar listed mass for starting, and subtracted the fuel mass based on the fuel listed in the readout on the launchpad. I checked my numbers a few times, I don't think I messed up on my fuel mass calculation. Maybe I missed something else important. Oh well.

Glad I've pointed you in the right direction, make sure you include some pics of the finished design.

Cupcake...

[thereaverofdarkness]

<iframe class="imgur-album" width="100%" height="550" frameborder="0" src="//imgur.com/a/ZWde0/embed"></iframe>

http://imgur.com/a/ZWde0#3

How do I get that embed to embed?

I got it to work! I read it at 5654 dV, less than 6000 after all but still more than I need! I'll add some landing struts to the final design but I've basically got a working lander! Thanks!

The two FL-T800 tanks detach during landing and backup tanks can be reattached at the refueling station. I haven't designed that part yet but I'm confident it'll be easy enough. Also, I maintained my 15 monopropellant the whole trip, so docking will be a cinch!

Edited March 11, 2015 by thereaverofdarkness

[manni01]

Yup, I would go with Cupcakes landers. His SSTOs are the most capable on these forums.

I beg to differ. His are really cool, indeed, but Overfloater's Cargo planes to Duna and Laythe (Mun and Minimus too) go there and even bring enormous cargos (up to 40t). As for looks, Cupcake would win. And for creativity Cupcake too (*caugh *caugh pa1983). Also, capable is a pretty loose word and can mean things in many ways. Sorry for being butthurt about this.

[Cupcake...]

I beg to differ. His are really cool, indeed, but Overfloater's Cargo planes to Duna and Laythe (Mun and Minimus too) go there and even bring enormous cargos (up to 40t). As for looks, Cupcake would win. And for creativity Cupcake too (*caugh *caugh pa1983). Also, capable is a pretty loose word and can mean things in many ways. Sorry for being butthurt about this.

I'm a huge fan of Mr Overfloater but our designs are very different beasts. For a start his have wings.

Seriously though, the main difference is his craft tend to use 4-8 Turbo Jet engines while unfortunately I'm still in the little league with my heaviest SSTO using just two Jet engines.

Also my SSTOs are designed as long range exploration vessels rather than cargo haulers.

Cupcake...

Edited March 11, 2015 by Cupcake...

[thereaverofdarkness]

I should start a line of spacecraft. I've always preferred highly symmetrical, generic-looking designs. No matter how sophisticated I make a craft, for some reason I don't want it to look sophisticated. I'm good at designing them for ease of use, good structural integrity, few parts, and easy to look at and tell what it can do. I also balance them well, making docking easy. Maybe people would like my designs?

[Cupcake...]

I should start a line of spacecraft. I've always preferred highly symmetrical, generic-looking designs. No matter how sophisticated I make a craft, for some reason I don't want it to look sophisticated. I'm good at designing them for ease of use, good structural integrity, few parts, and easy to look at and tell what it can do. I also balance them well, making docking easy. Maybe people would like my designs?

Well, there's one way to find out; put them out there and let people download them!

Cupcake...

[Mesklin]

You can use my 2 landers with comfortable cabin (very useful radar altitude) and all science equipment for Tylo (air analyzing device is not included)

1) Pure chemical (4 Rockomax 48-7S), 5429 m/s of dV, weight 13.8t, very hard to break and overturn, safe landing vertical speed is 10-15 m/s.

Can land to Tylo from 30 km orbit and return back to orbit with 200-300 m/s of spare dV (landing instructions: set periapsis 9-10 km, in time of landing do not make vertical speed more then 100 m/s, you should kill horizontal speed as low as possible - at altitude 500-1000 m). TWR at the end of landing >2, safe enough. Include upper docking ports near center of gravity for additional equipment, tanks or parachutes (for Laythe landing)

2) Twin LV-N engines, good dV - 6300 m/s (600-700 m/s of dV after return back to Tylo orbit), not good, but enough TWR (start TWR is 1.05, at landing time ~1.2), safe landing vertical speed is 5-10 m/s.

Landing instructions: set periapsis 9-10 km, in time of landing do not make vertical speed more then 30-40 m/s, you should kill horizontal speed as low as possible - at altitude 500-1000 m. Regulate vertical speed by pith of craft, not by thrust. Decrease thrust only almost at end of landing.

Download links:

http://www./download/a1ich281dm10myh/Tylo+sc+lander.craft

http://www./download/xa9r1ivl1i6zewo/Tylo+sc+lander+A.craft

[Himynameisjake]

Why fly when you can drive?

Bit of an ugly WIP, but it's capable of landing on Tylo, collecting all the science, then just drop down a fuel tank to refill it (hence the claw). Much more fuel efficient.

Javascript is disabled. View full album

[problemecium]

Will this do?

(There isn't currently a download, but I can make it available if you like it)

(Funnily enough the TWR and dV requirements for a Tylo lander made it so I didn't need a lift rocket to get it into Kerbin's orbit)

[thereaverofdarkness]

Oohh, you are a sciency type of kerbal. My favourite kind! And I see you already learned it yourself, but that's indeed the main lesson to draw from this thread: TWR matters! That, and that 48-7S are completely OP xD

SSTOx2 (down, then up) in Tylo can also be done with less fuel consumption, but more starting mass, using nuclear engines. But mind you, you have to start the burn with TWR a hair under one (which means a long careful reverse-gravity turn trajectory). Pretty much the only other sane option.

Rune. To actually make it easier to pilot, you have to go with two stages and >7km/s, or ISRU. Care for mods?

Yeah I tried the LV-N way before, but it was so inefficient with the long burn that I found it too difficult to work with.

I can't wait for stock In-Situ Resource Utilization but I prefer to mostly play without mods. Sometimes it's a fun challenge, sometimes it's laziness, sometimes it's not wanting to deal with mod bugs, sometimes stock is easier for the computer to handle, and sometimes it's just making sure myself and everyone else are on the same page. I played with Kethane a while back and I'd probably go back to it if it hadn't already been announced that Karbonite will eventually become stock.

[LifeGeek99]

I used Vector engines with Mk3 airplane fuel tanks and a refueling rig on the top.  Works with most designs, and easy to problem to solve.  Need a longer burn time?  Add more fuel.  Need more power? Add more Vector engines.  I needed to turn the vectoring range of the engines way down, otherwise landing was almost impossible.  Also, be careful with making your lander too tall.  Reaction wheels can only do so much.  

[septemberWaves]

@LifeGeek99 you've brought back this thread from March of last year. I'm not even sure Vector engines were part of the game back then. Plus, it seems like the original poster was looking for a vehicle that's not prohibitively large, and three-tonne engines don't exactly lend themselves to such a design.

[Frank_G]

I used this Lander for a Jool-5 mission. I landed on Tylo first, leaving the first stage behind and the remaining second stage had enough oomph for landing on the 3 other airless worlds. For Laythe an SSTO is by far the best solution. The Crater Flea, as i called it, is still available on my craftfile thread in the archive section, but many things have changed, since this mission. But it might give you some inspiration how to plan and build your own ascent vehicle.