Test a Tylo lander on Kerbin?

[maceemiller]

Hi all. So, 

Im very near to launching my Jool 5 challenge mission (after a few cancelled launches due to redesign of craft). Is there a way to roughly test my Tylo lander here on Kerbin? Maybe a height and speed to get to then land/take off using the lander? I dont want to use Hyperedit and never will so if theres no way to replicate this landing on Kerbin I'll have to learn when I get to Tylo.

Thanks

[Plusck]

Start in an 80x80 km orbit and bring orbital velocity down to 0 m/s at exactly 70km? If you touch the atmosphere you're dead...

Anything else would involve too many wrong variables. Are you using KER to check your TWR and dv? If not I think planning a landing on Tylo qualifies for "I can do this all manually and now I'm going to upgrade my HUD". 

[maceemiller]

7 minutes ago, Plusck said:

Start in an 80x80 km orbit and bring orbital velocity down to 0 m/s at exactly 70km? If you touch the atmosphere you're dead...

Anything else would involve too many wrong variables. Are you using KER to check your TWR and dv? If not I think planning a landing on Tylo qualifies for "I can do this all manually and now I'm going to upgrade my HUD". 

Yes im using KER. I seem to, by your reply, asked a maybe impossible to answer question. Tylo becomes more daunting every day.....

[Plusck]

6 minutes ago, maceemiller said:

Yes im using KER. I seem to, by your reply, asked a maybe impossible to answer question. Tylo becomes more daunting every day.....

I'm very close to my first Tylo landing. It was all going fine until I decided to go mine on Bop to refill tanks before landing, and discovered that I couldn't exit the craft without dropping one of my (vital) stages. So if I'd landed like that I would never have planted a flag.

Since Tylo and Kerbin are so very similar, except for all that "slowing down in atmosphere" thing, I don't think there is much to do other than build what you know would get to orbit fine from Kerbin, then make sure it can actually land without falling apart, and include ISRU so that you can do it all again. After all - if it can take off then it certainly has a high enough TWR to land.

Or, I'd guess, you'd forgo refuelling and just use a Terrier+T400 to get most of the way back up to orbit, with smallish asparagused boosters to get TWR high enough, and stick that on top of a much bigger, orbit-capable (therefore Tylo-landing-capable) rocket.

[cubinator]

Landing on Tylo costs 2270 m/s, and returning to low orbit costs 2270 more.  That gets you a total required Δv of 4540 m/s.

Testing it on Kerbin won't give any sort of accurate results if you are using any but a select few engines whose TWR and Isp don't vary significantly with pressure, and the atmospheric drag will also impose design constraints  (read: flips) not present on Tylo. Therefore, I propose the following solution:

Landing on the Mun from low orbit costs 580 m/s. The return costs 580 more. The Mun's surface environment is a lot like Tylo's. If you want land on the Mun, return to orbit, and repeat this 3 more times, you would need a Δv of 4640 m/s. That's enough to land on Tylo and return to orbit with some leeway for orbital maneuvers and the like. So if you think your ship can land on Tylo and return to orbit, you should transport it to low Munar orbit and try landing on the Mun four times in a row without refueling. If your lander has two or more stages and not all of them are designed to withstand contact with the surface, you can simply hover above the ground bringing your velocity to zero. It gives the same effect in terms of fuel consumed. Bring enough RCS propellant to rendezvous and dock with a vessel in LKO, which is a similar environment to Tylo's near space. A ship that can successfully complete those tasks should be able to do a landing and return to orbit on Tylo, provided it is transported there first.

One last tip: Make sure your landing legs can function under Kerbin's gravity, which is similar to Tylo's. All you have to do is set the lander on the launch pad and see what it does. You don't have to fire the engines up on Kerbin at all; KER will tell you if the vacuum TWR is higher than 0.8 on Kerbin, or 1 on Tylo. As stated before, most engines suitable for a Tylo landing are basically worthless in Kerbin's thick atmosphere. Hope it helps! 

[Superfluous J]

I like both of the proposed tests, but if you've got KER installed then you really don't *need* a test All you need to know is:

1. Do you have 5000 total dV, split between at least 2 phases (pre-landed and post-landed)?
2. Does your ship have at least a local TWR of 2, near landing?

Note: TWR of 2 is not strictly necessary. I often land on Tylo with a TWR less than 2, but it can be pretty hairy and the more TWR you have, the easier it is. Also, 5000m/s is not strictly necessary but margins are good, especially far from home with an otherwise untested lander

[maceemiller]

Ok cool, thanks for your replies, very informative. So my lander has, at the moment,  4651m/s with a TWR of 1.4 for Tylo using KER's stats. I think I'll try to squeeze a little more fuel in then go for it. After all, what could go wrong? (Jebs famous last words.......)

[Foxster]

1 hour ago, maceemiller said:

Ok cool, thanks for your replies, very informative. So my lander has, at the moment,  4651m/s with a TWR of 1.4 for Tylo using KER's stats. I think I'll try to squeeze a little more fuel in then go for it. After all, what could go wrong? (Jebs famous last words.......)

You may find that pretty marginal. 

I appreciate your dislike for HE but I justify it to myself as running a part of a mission in the simulator before doing it for real, which is just what NASA does. 

[KerikBalm]

My stats for a tylo lander are: 4,900 dV, 1.2 initial TWR.

I'd prefer at least 5,000 dV.

I made a twin aerospike design with a full science suite, and 3 kerbal capacity - a reusable 3 kerbal single stage design... the margins are pretty thin though, in my test, I got back up to a 60x60 orbit with about 150 m/s left... or about 19 seconds to spare to set it down gently after arresting forward velocity... so coming to a stop 2km off the ground would not be good... that's 22 seconds of falling at 8 m/s/s... 178 m/s (ok, its not quite 8m/s).

But hey... its SSTO, and has the dV (with a refill) to visit every other airless moon in Jool and return to the fuel depot.

Anyway, without doing hyperedit.... you can do a rough test as suggested in orbit. The 80x80 orbit  down to 0 m/s at 70km is a good test... if you can do that you'll have plenty of dV... but the gravity is still stronger at 80km than 0km on Tylo, and the orbital velocity is higher. So... succeeding there will mean Tylo should be a cake-walk. You can use 0 surface velocity instead of 0 orbital velocity to approximate the lower orbital speed (as Tylo rotates slower than kerbin, your surface velocity relative to a non-rotating reference frame is lower than on Kerbin)

If you go to a higher orbit where the gravity is only 0.8 g's, that should work... but your orbital velocity will still be a bit too high... so going to 0m/s surface should be a good approximation.

if 600 km(radius of kerbin) is 1.0 Gs, then 864 km should be 0.8 Gs... so... 264 km above the surface of Kerbin.

Start in a 274x274km orbit, and bring it down to 264km with 0 surface velocity for your test?

Of course, tylo has mountains which will complicate things, whereas you can skim down to 264,001 m without hitting anything or going below 264,000 and failing the test... but yea... that's the closest you can get to a tylo simulation without leaving kerbin's SOI

[Gojira1000]

I'm sloppy - anything I land on Tylo I need to have good TWR and at least 5K dV in the tank.

[maceemiller]

8 hours ago, Foxster said:

You may find that pretty marginal. 

I appreciate your dislike for HE but I justify it to myself as running a part of a mission in the simulator before doing it for real, which is just what NASA does. 

Ive been thinking about your comment about HE. I do quite a bit of sim racing and spend more time on track practicing than on race day, so really testing at Tylo is no different? On that basis I think I will have a look at HE. Thanks for prompting a thought in my head

[maceemiller]

Well, quick post.........can now easily land and take off to orbit on Tylo. HE is actually very good.......felt a bit like cheating to start with however im getting more excited about my mission knowing the tools im taking with me will do the job........would be a tad upset and disheartened if id got to Tylo only to find out my lander was as much use as a paper shoe........

[Superfluous J]

1 hour ago, maceemiller said:

Well, quick post.........can now easily land and take off to orbit on Tylo. HE is actually very good.......felt a bit like cheating to start with however im getting more excited about my mission knowing the tools im taking with me will do the job........would be a tad upset and disheartened if id got to Tylo only to find out my lander was as much use as a paper shoe........

You just described me 2 years ago

[Kerbalstar]

Another mod to try is KRASH Kerbal Ramification Artificial Simulation. I don't remember what the H stands for.

[fourfa]

On 4/5/2016 at 6:59 PM, 5thHorseman said:

I like both of the proposed tests, but if you've got KER installed then you really don't *need* a test All you need to know is:

1. Do you have 5000 total dV, split between at least 2 phases (pre-landed and post-landed)?
2. Does your ship have at least a local TWR of 2, near landing?

Note: TWR of 2 is not strictly necessary. I often land on Tylo with a TWR less than 2, but it can be pretty hairy and the more TWR you have, the easier it is. Also, 5000m/s is not strictly necessary but margins are good, especially far from home with an otherwise untested lander

Just want to point out that if you have an initial, fully-fueled TWR of 2, you're probably more like 3-4 by the time you get close to the surface.  I'm usually comfortable with TWR 2 during the landing phase itself, which might translate to 1.2 in orbit.  Just something to think about.

[Mikki]

My best advice: start your descent from 10km orbit or lower... watch out for the mountainridges, there is a narrow valley equatorial.... you might pretty much orbit inbetween some rather large slopes...
Tylo is evil. Good luck.

[zarakon]

Build a thing that will get your pod into orbit

Then build a thing that will put that whole thing into orbit

Then build a thing that will get that thing to Tylo

Then build a thing that will get that thing into orbit

Edited April 21, 2016 by zarakon

[Renegrade]

I'd avoid HyperEdit (kraken attacks/mods aren't appropriate for testing etc) if at all possible.

A tylo orbit would look like this in a VESSEL in a save file:

			sit = ORBITING
			landed = False
			landedAt =
			splashed = False

and

			ORBIT
			{
				SMA = 640000
				ECC = 0
				INC = 0
				LPE = 0
				LAN = 0
				MNA = 0
				EPH = 0
				REF = 12
			}

(Tylo's REF index is 12 and it's radius is 600000m).

Always back up before editing or hyperediting anything of course, and this would best be done in a sandbox save (it's trivial to move .craft file between saves).

[maceemiller]

1 hour ago, Renegrade said:

I'd avoid HyperEdit (kraken attacks/mods aren't appropriate for testing etc) if at all possible.

A tylo orbit would look like this in a VESSEL in a save file:

			sit = ORBITING
			landed = False
			landedAt =
			splashed = False

and

			ORBIT
			{
				SMA = 640000
				ECC = 0
				INC = 0
				LPE = 0
				LAN = 0
				MNA = 0
				EPH = 0
				REF = 12
			}

(Tylo's REF index is 12 and it's radius is 600000m).

Always back up before editing or hyperediting anything of course, and this would best be done in a sandbox save (it's trivial to move .craft file between saves).

I appreciate your feedback but thats double dutch to me.....what ive found is yes, hyperedit is not the best answer, but my word when it comes to testing a craft in a situation its impeccable. Editing a .cfg file is not where I want to be if im honest. 

[Superfluous J]

1 hour ago, Renegrade said:

I'd avoid HyperEdit (kraken attacks/mods aren't appropriate for testing etc) if at all possible.

A tylo orbit would look like this in a VESSEL in a save file:

			sit = ORBITING
			landed = False
			landedAt =
			splashed = False

and

			ORBIT
			{
				SMA = 640000
				ECC = 0
				INC = 0
				LPE = 0
				LAN = 0
				MNA = 0
				EPH = 0
				REF = 12
			}

(Tylo's REF index is 12 and it's radius is 600000m).

Always back up before editing or hyperediting anything of course, and this would best be done in a sandbox save (it's trivial to move .craft file between saves).

I've had far more problems with me screwing something up editing the files than by using HyperEdit.

[Renegrade]

9 hours ago, maceemiller said:

I appreciate your feedback but thats double dutch to me.....what ive found is yes, hyperedit is not the best answer, but my word when it comes to testing a craft in a situation its impeccable. Editing a .cfg file is not where I want to be if im honest. 

Eh, it's not that hard.  If you aren't comfortable with it though, don't sweat it.

However, it's important to do backups no matter what tool/technique you use.

9 hours ago, 5thHorseman said:

I've had far more problems with me screwing something up editing the files than by using HyperEdit.

Never messed up a file yet.  Of course I'm quite careful, have an extensive programming background, and a decent text editor.  Part editing is a bit more hairy of course (especially when part orientation has four values, which is presumably a quaternion -- although again, never caused any issues), but orbit editing isn't exactly rocket science.  Well, unless you want something other than a circular, equatorial orbit.

And I have had HyperEdit break files or craft, and it was eating stuff for other people left and right during the pre-release.  I didn't run it during the PR of course, since it is in fact a mod and I believe wasn't updated until after the PR was over.

[Superfluous J]

7 hours ago, Renegrade said:

Never messed up a file yet.  Of course I'm quite careful, have an extensive programming background, and a decent text editor.  Part editing is a bit more hairy of course (especially when part orientation has four values, which is presumably a quaternion -- although again, never caused any issues), but orbit editing isn't exactly rocket science.  Well, unless you want something other than a circular, equatorial orbit.

And I have had HyperEdit break files or craft, and it was eating stuff for other people left and right during the pre-release.  I didn't run it during the PR of course, since it is in fact a mod and I believe wasn't updated until after the PR was over.

Your first sentence, I could say about Hyperedit. The worst it ever did was crash ships that I was trying to land and they fixed that long ago. And you are dismissing the very important aspect of Hyperediting your ships as opposed to editing the files: Time. It takes (possibly significant, when you're talking about your noncircular, nonequatorial orbits) time to quicksave, alt-tab out, find your ship, find the orbit info, change it, save it, and load the save. Then notice something wrong and have to go back and do it all again to make a change.

In HE, all you need do is - once you have all the numbers correct - switch to the visual mode and you can drag stuff around and very quickly set the orbit any way you want.

As far as moving parts around, yeah I gave up on that long ago. I COULD figure it out, but I dropped out of college for a reason: I don't WANT to have to figure some stuff out.