Long Range SSTOs?

[Meid]

Any tips? I can build planes and normal SSTOs, but I can only get to the Mun. I want to go to other planets, non-refuel.

[RoofCat]

learn gravity assists (slingshots) and reach even Eeloo.

Moho rather not without mining - 1000 escape to Eve with Mun assist, 2..3 free Eve assists, ~2000(?) slowdown at Moho, 900 landing, 900 launch, <2000 escape up to Eve, gravity assist up to Kerbin... very approximate numbers as I haven't used Eve assist for that, but it's rather over 6000m/s in the end. Probably doable with perfect ship not wasting any fuel with long burns... which is kind of oxymoron. High delta v ships use slow burns and thus waste some fuel turning theoretical delta v into real one. Do it and be my hero... for 5 minutes

I haven't managed to have more than 6200m/s left on LKO with Rapier/Nuke planes. 6000m/s are already quite hard. Now check how far 6000m/s can take you.
5000..5500m/s are quite common to have on decent Nuke planes launched with airbreathing Rapiers. So start with that limit.

You won't be able to go for Tylo though. Due to heavy landing not compatible with Nukes. Except you use mining SSTO, land on Vall/Pol/Bop first and have Ox tanks large enough for long closed cycle Rapier burns. Which you won't have on a plane.

For that reason I have build SSTAnywhere - Mammoth + Nukes rocket hopper with mining. Not a plane. No airbreathing engines used at all. Because airbreathing is wasted engine mass on anything but Laythe and Kerbin. Plane happens to be less universal than a rocket for that reason. Rocket SSTOs have even less delta v left on Orbit though. Max delta v on my SSTA was ~6500m/s from which you had just ~3000m/s on LKO. It had a lot of science and mining onboard though, science lab included for levelups so probably 4000m/s on LKO is doable on skinned down version. Still not a lot. But I solved the range choosing the right route - Kerbin - Duna- Ike - Dres - Laythe - Vall - Tylo - Pol ... something like that. To do Moho I actually had to do 2 stops at Gilly, both ways. If you use precise modded planers with perfect ejection angles, you may save one. Or perfect gravity assists.

And Eve landing/launch at sea level is plain impossible with SSTO. Even with mining. You have to leave something there. Often most of your ship on the way up.


Start with Duna. Then go for Laythe. Those are rather easy targets you can actually reach without any gravity tricks. Duna is close and Laythe is airbreathing.

[JoeDaTomato]

Use ion engines for your orbital burns. My longest ranged (manned) SSTO has about 16000 delta-v after reaching LKO from ion alone, and about 4000 from areospikes engine (used for landing & takeoff). The reason for that is that high-thrust landings & takeoffs tend to be more efficient than low-thrust landings even with high ISP.

Don't bother with gravity assists unless you're going to make sure you've got a transfer window both to that planet, and to where you want to go afterwards. Orbiting 3-4 times around the sun waiting for eve to come back around is pretty immersion-breaking. The only bodies I use for assists are Ike and Tylo.

EDIT: I have a mod that reduces the Dawn's ISP to 3200 (it doesn't do anything else to it), so you'll probably have even better results than I do.

EDIT (to my edit): I was wrong, it added in a second ion engine with an ISP of 3200. This craft still uses 4200.

[RoofCat]

more like landing OR takeoff? You may not have enough delta v to land on Mun after your launch from Kerbin. And Dawn rather can't land you on Mun. You must be really light for that. On Minmus - doable if you aren't too heavy. So you may be limited to Minmus, Gilly, Bop and Pol as targets with return as an option. Probably Ike?
Nukes can do not just landing, but also launch back from Duna, Moho, Mun and other 0.2..0.3G bodies.

[JoeDaTomato]

Originally posted by RoofCat:

more like landing OR takeoff? You may not have enough delta v to land on Mun after your launch from Kerbin. And Dawn can't land you on Mun. On Minmus - if you are light. So you may be limited to Minmus, Gilly, Bop and Pol as targets with return as an option. Probably Ike?
Nukes can do not just landing, but also launch back from Duna, Moho, Mun and other 0.2..0.3G bodies.

You can land on the mun from munar orbit with 4000 delta-v. It takes ~580 for landing or takeoff on the mun lol (to/from low orbit.). I don't use the areospikes unless I'm actually doing the suicide burn or I'm actually taking off from the ground. It can land/take off from all bodies except Jool, Eve, the Sun, and Tylo (though I could might be able to push to to be able to do Tylo).

It can do one way to Eve and Tylo, though, for sure.

EDIT: I see your confusion. Those were the values of my Delta-V from LKO. I use jet engines to get off of Kerbin.

[RoofCat]

Originally posted by JoeDaTomato:

Originally posted by RoofCat:

more like landing OR takeoff? You may not have enough delta v to land on Mun after your launch from Kerbin. And Dawn can't land you on Mun. On Minmus - if you are light. So you may be limited to Minmus, Gilly, Bop and Pol as targets with return as an option. Probably Ike?
Nukes can do not just landing, but also launch back from Duna, Moho, Mun and other 0.2..0.3G bodies.

You can land on the mun from munar orbit with 4000 delta-v. It takes ~580 for landing or takeoff on the mun lol (to/from low orbit.). I don't use the areospikes unless I'm actually doing the suicide burn or I'm actually taking off from the ground. It can land/take off from all bodies except Jool, Eve, the Sun, and Tylo (though I could might be able to push to to be able to do Tylo).

It can do one way to Eve and Tylo, though, for sure.

EDIT: I see your confusion. Those were the values of my Delta-V from LKO. I use jet engines to get off of Kerbin.

so do you drop jet engines then? Because Jet engines plus Darts with still 4000 delta v sounds like full tanks - a bit too much payload for Xenon to carry over 16ooo delta v. There is something weird with that math. Either it is 16ooo with all Lf+Ox already empty or you are dropping something? It just sounds a bit too much. That's why I'm confused. Very light Xenon ships can have 23ooom/s, probably a bit more. But you are having 16k on a quite heavy ship. 4000 delta v for conventional engines is high considering you also have dead weight of jet engines as well. Something doesn't add up or has too many if's.

[JoeDaTomato]

Originally posted by RoofCat:

Originally posted by JoeDaTomato:

You can land on the mun from munar orbit with 4000 delta-v. It takes ~580 for landing or takeoff on the mun lol (to/from low orbit.). I don't use the areospikes unless I'm actually doing the suicide burn or I'm actually taking off from the ground. It can land/take off from all bodies except Jool, Eve, the Sun, and Tylo (though I could might be able to push to to be able to do Tylo).

It can do one way to Eve and Tylo, though, for sure.

EDIT: I see your confusion. Those were the values of my Delta-V from LKO. I use jet engines to get off of Kerbin.

so do you drop jet engines then? Because Jet engines plus Darts with still 4000 delta v sounds like full tanks - a bit too much payload for Xenon to carry over 16ooo delta v. There is something weird with that math. Either it is 16ooo with all Lf+Ox already empty or you are dropping something? It just sounds a bit too much. That's why I'm confused. Very light Xenon ships can have 23ooom/s, probably a bit more. But you are having 16k on a quite heavy ship. 4000 delta v for conventional engines is high considering you also have dead weight of jet engines as well. Something doesn't add up or has too many if's.

I do not drop the engines, but there are only two.

I don't really feel like reading each of your concerns and adressing them seperately, so I'll give you a rundown of where the numbers come from.

It takes off and gets into a sub-orbital trajectory with two Whiplash engines. The six Areospike engines burn ~600 Delta-V at the apoapsis putting me into a stable orbit (which I then circularize with the Xenon engines). At this point is where we've got the 16000 Delta-V with the Dawn. The sixteen Dawn engines burn over several orbits until I'm on an escape trajectory from Kerbin, then I burn however longer I have to to get to wherever I'm going. At this point, on average, I've got 4000 Delta-V with the Aerospikes.

I don't know what else to tell you, that's about it.

[JoeDaTomato]

Also, come to think of it, Jet Engines aren't that heavy. Why would it only make sense to you if I dropped them?

[RoofCat]

so you reach 1700m/s with Whiplash? Rather ~1400m/s. Then you add 600m/s and still miss 295m/s. Which is no easy task for still heavy ship to do on time with Xenon.

Anyway, that's not my main concern. Just targeting inaccuracies.
What I'm saying is, you rather won't have 16ooo m/s on Dawn with 3400m/s still in your Dart tanks. With empty - probably. So either you burn your Darts empty first and then fly for 16ooom/s without landing on anything harder than Ike, or you fly for lets say 8000m/s max (wild guess?) with Dawn first with still heavy ship and then land with those 3400m/s Darts. Or a mix of both. I'm not questioning your ship, just the math for a real trip. Of course, it is still enough to get to Moho and back. Which is furthest target. May be not enough for low solar rescue contracts (~22ooo total needed), but that's about it.
You still can't go to Tylo though as after landing you won't be able to lift off. Dawn can't do that (nor Nukes would except on almost empty ship) and Darts will be empty by that moment. Landing costs like Kerbin launch there. 3000+m/s easily.

As a side note - 2 Whiplash sounds like ~30t plane. While 6 Darts can do very comfortable TWR 1.5 vertical launch from Kerbin for a 60+t ship. So 6 Darts would be a bit overkill for 30t then even more so considering there is much less gravity on most other bodies and you also need less thrust on higher part of the Kerbin curve. The other way around - 60t plane may struggle to cross sound barrier with just 2 Whiplash.

2 Whiplash is 3.6t. Not much at all. But on a 30t ship that would be 12%. "Dry mass" for the whole trip. 6 Darts - 6t. Total 9.6t or roughly 1/3 dead weight from engines. That's not exactly small number. To be really efficient Darts need like 10t fuel each for launch. Which again means 70+t ship. If you have less than that, you have too many engines or not enough fuel. And again, 2 Whiplash pushing all that through sound barrier looks rather hard.


I know Operation40 did a lot of similar stuff with Xenon SSTO/planes. Also used some Darts. Just curious what exactly have you got. Have you got some pics? I have only used Xenon for rocket designs myself. Not a big fan due to slow burns and "too easy" solving any KSP universe distance. Polar probes most of the time and that's it.

[JoeDaTomato]

I said maybe for Tylo. I never tested it there.

Also I know that I put on too little jets, but I learned to fly with that. I just use a similar flight path to Matt Lowne's giant passenger SSTOs. Though, admittedly, this ship isn't nearly that cool :P

You were right about the 70+ tons, it's ~110.

And your innacuracies would be a fairly reasonable- for a normal ship. This has ~28 tons of Xenon and about the same in LF/O.

I totally get your feelings about ion engines- the time it takes to do a burn is painful. It's worth it, though, in my opinion.

Also I will link a picture (as an edit to this post within five minutes), but I won't keep it up after midnight (I live in EST.) (I'm protective of my crafts).

Please keep in mind that it's not designed to be praticle or pretty, it was designed to prove something (out of spite) to a friend of mine.

http://steamcommunity.com/sharedfiles/filedetails/?id=1310227971

[RoofCat]

thanks and no problem, saved screenshot for later tests :)
I see 100t bottom left. You can pass sound barrier with 100t and 11x 1.25m profile drag using just 2 Whiplash?

It honestly confuses me, I may have to do a few Whiplash tests soon. I have considered Rapiers the most powerful airbreathing engines and they can be used to launch 20..25t at best each except you use some boosters around 360m/s. Whiplash has much less thrust (theoretical 386kN max vs. 465kN on Rapier) and also lower top speed. Roughly 20% less power while the weight advantage is just 10%. Which kind of makes no sense. The plane is also rather long which adds quite some gliding drag early. You sure those are stock Whiplash engines in stock drag?

[JoeDaTomato]

Np. Yeah, it gets to about Mach 4. You just have to be really patient.

You might be right about Rapiers, but I only really use them on light craft. I might be wrong for doing that, I haven't done much work with them.

[RoofCat]

in my experience being really patient means you just burn extra fuel until you are light enough to reach higher speed. So slightly less fuel does basically the same. That's why I try to not exceed ~20t with Rapiers. Fuel may be free, but empty tanks are still heavy.

Anyway, I'm too theoretical right now. Have to do more tests with Whiplash again.

[JoeDaTomato]

Originally posted by RoofCat:

Anyway, I'm too theoretical right now. Have to do more tests with Whiplash again.

Lol. Good luck!

[The Man]

watch matt lowne :P