SSTO Tylo No Refueling Or Docking

[Laie]

On 7.11.2017 at 2:32 PM, Nefrums said:

This would require a lot of dV, even with gravity assists
LKO -> Tylo:   1050m/s + another ~ 7-800m/s to get to low orbit.
Tylo landing: ~4600 m/s
Low Tylo orbit -> kerbin ~1000 m/s

I know that 4600m/s for Tylo landing and ascent is quite tight. Do the other figures have a similarly small margin of error?

[quasarrgames]

Would love to participate in this challenge.

On 17/11/2017 at 3:06 PM, sevenperforce said:

Going in the opposite direction...

How much does gear mass, exactly?

I'm just thinking: gear is really only needed on takeoff. You don't actually even need it on landing; you can ditch in the ocean at survivable speeds if you're careful enough and you do a little design work. For the rest of the trip, it's dead weight.

What if you take off the landing gear, make it a tailsitter VTOL, and add a single Dart? Might be a slight increase in mass, but that Dart will give you a HUGE advantage for your landing burn over RAPIERs alone, both in terms of isp and in terms of terminal TWR.

A tailsitter VTOL can have a TWR of 1.001; you just punch all the engines and then slowly tilt forward until you build up enough forward speed for lift to take over. Then you'd have a TWR of closer to 3-4 by the time you get to Tylo.

Only problem is you'll need a lot of dry engine mass to make a VTOL, more than the gear would take away (gear set only weighs 0.135t in total). However, using a VTOL would bring this challenge into the realms of some of the best pilots in the biz, like @Cupcake....

Also, aren't kerbals in chairs worth it purely because they're lighter than any probe core + antenna with strong enough range?

Finally, have any of you had success with building up speed in the upper atmosphere? I've been trying shallow zoom climbs, but i can rarely get above 1500m/s without sacrificing almost all my vertical speed.And this is with a TWR of 0.38.

On 16/11/2017 at 9:01 AM, Zhetaan said:

For example, one thing I intend to explore is the touch-and-go landing where the landing gear contact the ground but the vessel does not stop before taking off again.

This touch-and-go tactic is easily exploitable, and can make the challenge comparatively easy. I've been experimenting with it too. You take a long needle made of fairings that weighs about half a ton, and fly at orbital velocity JUST low enough that the needle skins the top to tylo's mountains. The ship goes pinwheeling like a madman, but fairings are indestructible, and provided you've strutted your ship up nice and snug it'll survive. 

Highest delta V i've been able to get was 6700m/s, and only about 1000m/s of that was non-nuclear.

In desperation i compiled a list of exploits that MIGHT be considered ok in this challenge, but i have no idea:

-clipping tons of fuel tanks inside service bays and fairings so they don't have drag

-sliding bare-bottom across the runway without landing gear

-Starting your craft on high launch clamps (how high is too high?)

-bringing a capsule, which just so happens to come with infinte eva propellant, so you can get out and push™ infinitely (ableit VERY tediously)

Edited November 21, 2017 by quasarrgames

[FleshJeb]

I've been attempting this with various combinations of Rapiers and Nervs. Primarily with a 3R x 2N.

My payload is a service bay with an OKTO 2, 4 mini reaction wheel, the smallest battery and an RTG. I'm assuming there's a comms infrastructure at Jool, and have CommNet turned off.

I haven't succeeded yet, and I don't think it's possible without ions to do the Jool transfer. Maybe not even then.

The testing involves:

• Flying the plane to LKO. Thank you to @AeroGav for forcing me to get MUCH better at spaceplanes.
• Dumping the appropriate amount of fuel for a highly-optimized gravity-assisted transfer and circularization at Tylo (assuming 1850 m/s).
• Cheating minimum orbit for Tylo (45.xxx km)
• Attempting a Constant Altitude Landing, and finishing with a short LFO burn from the Rapiers.

Thus far, I'm coming up short, and won't be able to finish lifting again. I have a spreadsheet that calcs remaining delta-V at each phase, and I'm coming up AT LEAST 1500 m/s short for the return. (assuming Tylo - Kerbin = 1000 m/s).

@AeroGav, If you're willing, could you:

• Build a 2 Rapier, 3 Nerv plane that has 12 tons of LFO in reserve for Tylo operations, with as much LF as you can pack on it.
• Fly it to LKO (90x90) and tell me how much LF is remaining.
• Share the craft.

I believe I can fly it down to Tylo and back up. (I'll need to install HyperEdit to get a lower Tylo orbit.) The testing time is killing me.

I'd prefer to try a 3R x 4N, (arranged as 1N + 3N + 3R for tail-sitting stability) but I think the mass fractions start to get suboptimal after 1R : 1.5N.

 

[Nefrums]

14 hours ago, Laie said:

I know that 4600m/s for Tylo landing and ascent is quite tight. Do the other figures have a similarly small margin of error?

Yes, And 4600 is a Tylo landing with good twr. Lower twr means more gravity losses.

 

It is possible to do the transfers from LKO to low tylo orbit and back with a single ion engine.   Just add ~1000ec of batteries and a rtg.   But that would mean several hundred 2min pe kicks. 

I have flown that with a <10t ship, and even that required ~20 PE kicks to escape kerbin.

  

Edited November 21, 2017 by Nefrums

[HeroBrian_333]

You are all thinking too conventionally. Think about other propulsion methods other than ion and nervs. I hear SRB' s have a good TWR. Only problem is dry mass after they are spent. Also, @DAL59 never awnsered my question, so I'm taking that as a yes. See you on Tylo! (And Kerbin when I get back)

[DAL59]

6 hours ago, quasarrgames said:

-clipping tons of fuel tanks inside service bays and fairings so they don't have drag

-sliding bare-bottom across the runway without landing gear

-Starting your craft on high launch clamps (how high is too high?)

-bringing a capsule, which just so happens to come with infinte eva propellant, so you can get out and push™ infinitely (ableit VERY tediously)

All acceptable.  But no pushing all the way to tylo.  

[HeroBrian_333]

@DAL59 any stock propulsion source is allowed? I know one (I'm not saying what it is here, but if you would like I can PM you) with a lot of DeltaV

Ok, I can show how to beat this, just add a badge for whoever completes it. I will not only get an SSTO to Tylo,  I will have it carry a rover, a flatpack outpost frame, a science lab, a hitchiker crew container, a comm tower, a skycrane, and 10 extra crew other than the SSTO crew. SSTO will not refuel, not shed any parts, and land (somewhere) on kerbin safley.

Edited November 21, 2017 by HeroBrian_333

[Laie]

Throwing together a quick mock-up in the VAB, I see no way how to get there.

Working assumption is that Rapiers shouldn't be burdened with more than 15t each, and that a single ion engine can be used for all the periapsis-kicking (out from Kerbin, down to and up from Tylo). It doesn't even get close.

[HeroBrian_333]

8 hours ago, HeroBrian_333 said:

You are all thinking too conventionally. Think about other propulsion methods other than ion, rapiers, and nervs. I hear SRB' s have a good TWR. Only problem is dry mass after they are spent. I have a way! See you on Tylo!

 

[AeroGav]

14 hours ago, FleshJeb said:

hus far, I'm coming up short, and won't be able to finish lifting again. I have a spreadsheet that calcs remaining delta-V at each phase, and I'm coming up AT LEAST 1500 m/s short for the return. (assuming Tylo - Kerbin = 1000 m/s).

@AeroGav, If you're willing, could you:

• Build a 2 Rapier, 3 Nerv plane that has 12 tons of LFO in reserve for Tylo operations, with as much LF as you can pack on it.
• Fly it to LKO (90x90) and tell me how much LF is remaining.
• Share the craft.

I believe I can fly it down to Tylo and back up. (I'll need to install HyperEdit to get a lower Tylo orbit.) The testing time is killing me.

I'd prefer to try a 3R x 4N, (arranged as 1N + 3N + 3R for tail-sitting stability) but I think the mass fractions start to get suboptimal after 1R : 1.5N.

I can probably take a look on Thursday.

If I was going to go there again, it would be with something more like the Starion you've played with from the "winged TWR" thread.   I'd give it a small resource converter and drill, replace one nuke with a rapier.     Come in to land on Tylo by setting Retrograde hold, throttling to 100% (so full thrust on the two nukes) and then manipulating the thrust limiter on a single RAPIER to land it.      That dumps two Whiplash jets in Kerbin's upper atmosphere and involves mining, but it's the most convenient way for me to get there.  No docking, no gravity assists, and hopefully comfortable margins.

 

I have previously been to Tylo on a Spaceplane in my Jool 5 mission.   The craft is on my KerbalX,  called the "Steven Tylo".    It's a staged spaceplane,  has about 4300 dv in LKO so it can go direct to Jool.   Then land on one of Jool's moons (usually LAythe) to refuel, then in Tylo orbit, it can deploy a lander rocket.     It is a huge airplane, two and a half of the longest mk3 cargo bays long,  and the Tylo lander rocket is 2.5m in diameter with 6 seats.   Unfortunately the ladders don't work, so any Kerbals that climb down to plant a flag will get stranded on the surface.

 

[FleshJeb]

7 hours ago, AeroGav said:

I can probably take a look on Thursday.

If I was going to go there again, it would be with something more like the Starion you've played with from the "winged TWR" thread.   I'd give it a small resource converter and drill, replace one nuke with a rapier.     Come in to land on Tylo by setting Retrograde hold, throttling to 100% (so full thrust on the two nukes) and then manipulating the thrust limiter on a single RAPIER to land it.      That dumps two Whiplash jets in Kerbin's upper atmosphere and involves mining, but it's the most convenient way for me to get there.  No docking, no gravity assists, and hopefully comfortable margins.

That would be much appreciated. You're certainly under no obligation--I just figured if that you couldn't design and fly a nearly optimal atmospheric portion, very few could.

Also, while I was staring at the ceiling last night, I had the very same thought about thrust-limiting the Rapiers.

FYI, I think you were right about designing the Tylo lander and working backward. So, hold off for a bit. 4 Nervs and 1 Rapier look much better, but that's never leaving Kerbin without tossing parts.

Before my laptop expired, I had a very accurate spreadsheet for computing CALs. I was able to predict dV expenditures and halt over my landing area to about 2% So, I made a new one.

Using approximate numbers for the SSTTs I've already got (around 55 tons in Tylo orbit), I attempted to calculate several varieties of CAL. I'm burning somewhere around 9-12 tons of LFO just for the CAL portion, and not counting the suicide burn. This is looking pretty bad. The numbers below are for 2 Rapiers and 3 Nervs. I can run the Nervs as high as 60 degrees off of retrograde and still be more efficient than the Rapiers.

It's pretty tedious to change variables and track outcomes. I'm still trying to determine a combination of residual horizontal velocity and TWR to begin the suicide burn at. Prior experience says efficiency falls off badly after TWR 1.7.

This would be better done programmatically. Since I'll be having kRPC doing the landing for me, I might as well do it in that.

A handy diagram (3x vertical exaggeration):

 

 

 

Edited November 22, 2017 by FleshJeb

[sevenperforce]

Using the "clip tanks inside fairings" and "cancel tail drag by attaching, rotating, and offsetting engines" tricks, I can put a 48-tonne SSTO into LKO with four RAPIERs, one nuke, 1292 units of oxidizer, and 6928 units of liquid fuel. Did it pretty easily, too, so if you need more margin I can try again. Is that enough to make it to Tylo, land, orbit, and return?

The SSTO has wheels, Jeb in a command seat, wings, and control surfaces, so it can land deadstick as long as it can get a good Kerbin aerocapture trajectory.

[FleshJeb]

57 minutes ago, sevenperforce said:

Using the "clip tanks inside fairings" and "cancel tail drag by attaching, rotating, and offsetting engines" tricks, I can put a 48-tonne SSTO into LKO with four RAPIERs, one nuke, 1292 units of oxidizer, and 6928 units of liquid fuel. Did it pretty easily, too, so if you need more margin I can try again. Is that enough to make it to Tylo, land, orbit, and return?

The SSTO has wheels, Jeb in a command seat, wings, and control surfaces, so it can land deadstick as long as it can get a good Kerbin aerocapture trajectory.

I ran it through my range-estimation spreadsheet (which has a few errors), and it looks like it might. I'll have to tune it up, but I can't do it today.

Hmm, something's screwy...I'm calculating a dry mass of 6.9 tons, and your engines should weigh 11. Is that 48 tons in the hangar, or in orbit?

[AeroGav]

15 hours ago, FleshJeb said:

. 4 Nervs and 1 Rapier look much better, but that's never leaving Kerbin without tossing parts.

Not necessarily, though probably wouldn't get though mach 1 with a large tonnage.     With a mk1 fuselage,  I have gotten a 60 ton takeoff weight to orbit using 2 nervs and 1 rapier and only liquid fuel.        What's the limit there?    Imagine finding that would involve climbing very slowly and patiently subsonic to a good altitude, then lighting all 4 nukes and going into a shallow dive to get up to mach 1.5.   After that the RAPIER  will bring you to 1300 m/s all by itself.

Of course much easier if you can afford  a 1.2 ton panther to help you out up to 800 m/s,  but it's up to you ultimately.      Subsonic lift drag ratios of over 7:1 are possible, which means it is possible to climb with an airbreathing twr of worse than  0.16 to 1,  if you are very patient.

 

[AeroGav]

On 22/11/2017 at 8:46 PM, AeroGav said:

Not necessarily, though probably wouldn't get though mach 1 with a large tonnage.     With a mk1 fuselage,  I have gotten a 60 ton takeoff weight to orbit using 2 nervs and 1 rapier and only liquid fuel.        What's the limit there?    Imagine finding that would involve climbing very slowly and patiently subsonic to a good altitude, then lighting all 4 nukes and going into a shallow dive to get up to mach 1.5.   After that the RAPIER  will bring you to 1300 m/s all by itself.

Of course much easier if you can afford  a 1.2 ton panther to help you out up to 800 m/s,  but it's up to you ultimately.      Subsonic lift drag ratios of over 7:1 are possible, which means it is possible to climb with an airbreathing twr of worse than  0.16 to 1,  if you are very patient.

 

OK,   this is what  a 4 nuke 1 rapier spaceplane looks like , 48.5 tons.    As requested, I included some oxidizer - ft400 and ft800 tank's worth.

Action group 1 is "nose up" trim flap, action group 2 neutral,  action group 3 nose down.   AG 5 = nuke on/off.   It is intended to be flown on prograde hold with navball in surface mode while in an atmosphere.

We are close to the limit of what a single RAPIER can do.     It rolls down the whole length of the runway with a 0.2 to 1 TWR,  flops off the end at 80 m/s and slowly starts to climb.    As the air gets thinner,  our TWR getes even worse.    When drag reached 85% of thrust,  i planned to activate the nukes and push us supersonic.    At one point, it looked like that was going to be not much more than 2km.     But,  as we got above 3km, the rapier's thrust started to fall more slowly than drag,  and as our mach number increased, the deathly gurgling gave way to some healthier sounds,  even with a hint of hissing.      

Just shy of 7800m I activate the nukes and set nose down trim, till over mach 1.5, whereupon the ramjet boost enabled the rapier to take us the rest of the way to our airbreathing top speed unsassited. It would probably have gotten supersonic if I just did nothing.

To cut a long story short, we reach orbit. 

The large mass of oxidizer really cuts into our delta V.    We are only a little bit below 1.0 TWR on nuke power alone.      Adding a Panther engine would mean we could double the takeoff weight of our craft and bring a lot more fuel to orbit. at the cost of 1200kg extra dry mass.     We could loose that cockpit and just have a probe core.  If we really want a kerbal they can go in a command chair in a service bay.      But even with all that i still think we're nowhere close to pulling this off.

 

Share link here -

https://www.dropbox.com/s/5exj5oqwy13nsmn/tylo1 test flight.zip?dl=0

contains 4 files, the craft, and 3 save files so you don't have to relive that 44 minute climb to orbit.

 

[sevenperforce]

On 11/22/2017 at 3:11 PM, FleshJeb said:

I ran it through my range-estimation spreadsheet (which has a few errors), and it looks like it might. I'll have to tune it up, but I can't do it today.

Hmm, something's screwy...I'm calculating a dry mass of 6.9 tons, and your engines should weigh 11. Is that 48 tons in the hangar, or in orbit?

48 tonnes after reaching orbit.

[FleshJeb]

On 11/23/2017 at 2:33 PM, AeroGav said:

 

Share link here -

https://www.dropbox.com/s/5exj5oqwy13nsmn/tylo1 test flight.zip?dl=0

contains 4 files, the craft, and 3 save files so you don't have to relive that 44 minute climb to orbit.

 

Thanks, mate. Got it downloaded, and I'll put it through its paces this weekend.  I got the landing script structured. Now I just have to figure out which bloody reference frames to use for the various readouts.

EDIT: I've just checked out Throttle Controlled Avionics again. I think I can make it do this without writing it myself. That takes the fun out of it, but I'd rather get it done.

Edited November 29, 2017 by FleshJeb

[Matt Lowne]

Another impossible challenge. There really needs to be a rule that OP has actually verified that what they're asking is possible without mods.

Edited December 10, 2017 by Matt Lowne

[sevenperforce]

1 hour ago, Matt Lowne said:

Another impossible challenge. There really needs to be a rule that OP has actually verified that what they're asking is possible without mods.

That is a rule, generally, but in this case the thread is more about "I think this can be done, but I'm not sure; let's work together and find out."

[JacobJHC]

1 minute ago, sevenperforce said:

That is a rule, generally, but in this case the thread is more about "I think this can be done, but I'm not sure; let's work together and find out."

With a kraken drive, anything is possible

[DAL59]

K-drives are welcome, but will be placed in a separate category.  

 

 

[KingDominoIII]

If we’re still doing this- have we considered going Matthew Karr style and “bumping off a bit” on Tylo: knock off empty tanks/jet engines on a mountain while in a low orbit, and then boost up at apoapsis and return to Kerbin. It’s a crash-landing, so there’s no need to return for a second landing requiring a high TWR.

 

[HeroBrian_333]

6 hours ago, KingDominoIII said:

If we’re still doing this- have we considered going Matthew Karr style and “bumping off a bit” on Tylo: knock off empty tanks/jet engines on a mountain while in a low orbit, and then boost up at apoapsis and return to Kerbin. It’s a crash-landing, so there’s no need to return for a second landing requiring a high TWR.

 

Breaking parts is probably cheating, and this thread is pretty much dead. Sorry, I just bear the bad news.

[DAL59]

On 2/20/2018 at 6:06 AM, HeroBrian_333 said:

Breaking parts is probably cheating, and this thread is pretty much dead. Sorry, I just bear the bad news.

Breaking parts is not cheating, this thread is not dead, and I will not be the last jedi!  

[JacobJHC]

2 hours ago, DAL59 said:

Breaking parts is not cheating

But planned part breaking is essentially staging the rocket.