SSTO Troubles

[Xyphos]

THIS IS NOT A WHINE THREAD - I want that to be perfectly clear before continuing.

I've been messing with various Mk3 SSTO designs with the intention of putting it in orbit around Minmmus so it can be refueled before leaving Kerbin's SOI.

So far, 9 of 11 designs were able to achieve a stable orbit between 72kM and 80kM around Kerbin, but lacked the fuel required to make the trip out to Minmmus' SOI,

in fact, they've barely had enough fuel to de-orbit themselves back to KSC.

and none of them had enough fuel to make an inclination adjustment to rendezvous with an orbital refueling station, either.

I just want to know, if anyone has had any success getting an Mk3 SSTO vessel to Minmmus, and advise on how it was done.

Thanks!

Edited August 1, 2015 by Xyphos

[selfish_meme]

It's possible but you are going to cut down your cargo enormously, take my (shameless self plug) OrbitMaster , it gets a full orange tank to orbit, you could then use that fuel to go somewhere, but you would be trading cargo space for fuel. The best use case for SSTO spaceplanes (I assume you are talking about spaceplanes, that's what everyone has trouble with) is cargo (fuel) to LKO, then use different craft to do runs to other planets.

[Xyphos]

So, I assume that's a "No" - meaning that SSTO's are only good for orbital probe launches and tourist attractions.

tho, your OrbitMaster is an excellent idea.

Edited August 1, 2015 by Xyphos

[AaronLS]

So, I assume that's a "No" - meaning that SSTO's are only good for orbital probe launches.

Pretty much. You could probably find a design that is VERY extremely large that might make SOI. The thing is an SSTO is essentially stretching the limits of the first stage by not shedding any non critical components/tabks. The only reason they are cost effective is that they can get to orbit cheaper by using airbreathing engines and wings for lift. Once you get into orbit, you are being very wastful to get any further.

I usually get my payload to orbit then use another SSTO to deliver fuel for a tug that pushes the payload to SOI. The tug decouples with enough fuel to get back into SOI and air brake back into a low orbit.

[Lutheror]

SSTO's are a lot harder now but I'm sure it can be done

[selfish_meme]

You can SSTO Spaceplane to Mun, Minmus, Duna and Lathe, or any airless low grav world. The trick is taking everything you need with you. They don't even need to be that big, see the SSTO to Laythe challenge. Your cargo is fuel and or the equipment to refuel. Head to Minmus to refuel then go wherever you like.

[MalfunctionM1Ke]

You can easily go places with an ion probe once it is in Orbit.

I do that all the time for mapping planets.

But yeah, i never had nearly the fuel left to go anywhere else than LKO in a spaceplane.

[Evanitis]

i never had nearly the fuel left to go anywhere else than LKO in a spaceplane.

Same here. And checking the Pro SSTO pilot thread shows, that even my orbits are like 10km lower than what the experts achieve. I just keep my fuel on LKO. I might need a few hundred extra dV for going interplanetary, but my gas-station is right in my backyard and I don't have to hassle with Minmus inclination.

And if I really need that dV, I can just refuel twice in Kerbin SoI.

[Sharpy]

I made it with some 1500m/s of delta-V in an MK3 monster (Rhino, 16 whips and 4 orange tanks as "engine fuselages" around the MK3 body). I could have gone to Minmus and back in it, though with very little payload.

But the standard approach is to have a refuelling station in LKO. The spaceplanes usually have lots and lots of delta-V when fully fuelled, they just lose it all on ascent.

Catch an asteroid, put it in LKO, read a guide how not to deplete the asteroid rapidly, and enjoy a good refuelling station.

[hazard-ish]

From my experience, its best to use RAPIERs in airbreathing mode rather than turbojets since they produce greater thrusts at higher speeds and shock cone intakes are by far the best suited for SSTOs since they produce much less drag than other intakes at high speeds which is essential for helping the nuclear engines kick you into orbit. Also, I don't end up using much oxidizer for the RAPIERs, just burn a pair of nuclear engines so as long as you need - starting before the jets flame out.

Check out my youtube channel to see how I got some reasonably good SSTOs to work in the new aero. Recently I got an SSTO to the Mun and back so by using a similar ascent profile, your designs should have enough delta-v to get out to Minmus orbit!

[Wanderfound]

So, I assume that's a "No" - meaning that SSTO's are only good for orbital probe launches and tourist attractions.

tho, your OrbitMaster is an excellent idea.

Actually, no; interplanetary Mk3's aren't that hard to do.

Basically, you want enough RAPIERs to get off the runway, enough oxidiser to lift the apoapsis, an LV-N or two and as much LF as you can carry. Do that right and you can reach Minmus; stash some ISRU gear in the cargo bay and you can reach anywhere.

To demonstrate:

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(that's a FAR ship, but the differences from stock aren't that big these days)

Really, though, if you're going for interplanetary spaceplanery, you should be stopping for a top-up in LKO to replace the fuel expended during launch. It massively increases your capabilities, and an orbital fuel depot can be established for virtually zero cost if you lift the fuel via spaceplane tanker.

[GoSlash27]

So, I assume that's a "No" - meaning that SSTO's are only good for orbital probe launches and tourist attractions.

tho, your OrbitMaster is an excellent idea.

Not at all.

#1) SSTO spaceplanes can be built to go as far as you want. It's just a matter of reducing payload fraction for more fuel/ more efficient engines.

#2) Although long distance SSTOs are feasible, I don't use them that way. I don't see the point of dragging all that unnecessary equipment to another planet.

#3) the prime mission of the SSTO spaceplanes in my program isn't probe launches or tourist attractions, but rather transporting supplies and shuttling crews to/ from a station in LKO. They are super cheap, safe, and reliable delivery vans.

Best,

-Slashy

[Pecan]

It doesn't stop being magic just because you know how it's done.

It doesn't stop being 'Single Stage' just because you refuel it. Basically, anything that can SSTO with a docking port can Single Stage to any body's orbit.

'To Orbit' stops being relevant if it's designed to go to further without refuelling though ^^.

(Like the others, I use (have used, pre-1.x) spaceplanes for delivering light payloads to orbit, SSTO rockets for heavier ones and space-only vehicles for moving everything around once it's up there).

[Frank_G]

...and shock cone intakes are by far the best suited for SSTOs since they produce much less drag than other intakes at high speeds...

Thank you for that vital information! I will try that immediately on my latest design.

[hazard-ish]

Great - I'm glad I could help. Good luck with the latest design

[Val]

Here's a Mk3 SSTO spaceplane I built just to reply to this thread.

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Craft file

Edit: Made a small mistake in the Action groups, so had to update the design a little.

---

Here's a quote of a post I did in another SSTO thread where I tried to describe what guidelines I use for building SSTO's.

I have a few design guides that I use, for pure Rapier SSTOs that only go to LKO.

For each Rapier you need:

• LF tankage: 2x Mk1 Fuselage or 1x Long Mk2
  
• LFO tankage: 1x FL-T800 or 1x Long Mk2 or other equevalents, that add up to the same amount.
  
• Wing Area: 3 (2-2.5 main wing, rest for horizontal stabilizer) + Control surfaces + Vertical Stabilizer.
  
• Intakes: 1x Shock cone (lowest drag)
  

This will allow you to lift 4.5 t to orbit comfortably. 5 t just barely.

The 4.5-5 t is the rest of the craft and cargo:

• Cockpit
  
• RCS+Monoprop
  
• Cargo bay with cargo.
  
• Landing gear
  
• Batteries
  
• Power Generation
  
• Reaction Wheel
  

Other things of note:

• The only recommended surface attachments are, Wing parts (incl. Airbrakes) and Retractable Wheels. Fuel tanks are OK, if used to mount an engine and intake. RCS may be needed. Everything else goes in a cargo or service bay. I even put Radiators in the cargo bay.
  
• As little control surface as is necessary. On many of my single Rapier designs i only have 2 control surfaces. Combined Roll and Pitch in a V-tail or Elevons.
  
• I always mount wings with a little upward angle, so I can have positive lift, even with the craft at zero degrees pitch, at high enough speed.
  
  • I do it mostly to minimize drag around and right after Mach 1.
    
  • Because it's better to have only the wings at an angle to the airflow, than the whole craft.
    
  • I aim for neutral lift around 375 m/s, at sea-level. At 9 km this gives neutral lift around 600-800 m/s.
    

Once I've built my SSTO, I evaluate it's performance using quick tests, that I've found to work for me. It takes a maximum of 4 minutes to test the basic viability of a new SSTO. That is not to say, that an SSTO which fails my tests, can't get to orbit. But it will probably take much longer than it needs to and probably uses more fuel than needs.

Which brings me to the ascent profile. I don't use the standard, slow climb to 10 km. I fly pretty much level right off the runway and don't start climbing until I hit 450 m/s. I've found this to be the most efficient ascent for my designs. Especially the heavier ones, many of which could not climb past 5 km with the standard ascent.

I baked the tests into this album.

http://imgur.com/a/3Sg6v

Craft file

In general I prefer combined Rapier/Nuke SSTOs. I find them to be much more efficient than pure Rapier. They use a very similar ascent profile. There's a bunch in the SSTL album in my signature. Mostly made from Mk1 parts, but there's a few made from Mk2 and Mk3 parts, also.

Here's a proper Rapier/Nuke SSTO: G+ post (with craft files). Although that one is a bit overpowered. It doesn't need a sea-level acceleration. It can accelerate through a shallow climb.

Hope it helps.

- - - Updated - - -

Actually, no; interplanetary Mk3's aren't that hard to do.

Basically, you want enough RAPIERs to get off the runway, enough oxidiser to lift the apoapsis, an LV-N or two and as much LF as you can carry. Do that right and you can reach Minmus; stash some ISRU gear in the cargo bay and you can reach anywhere.

To demonstrate:

http://imgur.com/a/IbXOa

(that's a FAR ship, but the differences from stock aren't that big these days)

Really, though, if you're going for interplanetary spaceplanery, you should be stopping for a top-up in LKO to replace the fuel expended during launch. It massively increases your capabilities, and an orbital fuel depot can be established for virtually zero cost if you lift the fuel via spaceplane tanker.

That is a pretty cool Spaceplane/SSTO, Wanderfound! Edited August 1, 2015 by Val
Updated craft file

[Xyphos]

Now see, most of my designs were the standard slow-climb to 10k, I never once considered going super-sonic straight from the runway. *facepalm*

also, I've never thought about using nervas for ascent, I didn't bother because of their weight, low thrust and the fact that I just launched a nuke tug into orbit.

I'm going to try again. Thanks for the inspiration, everyone!

Edited August 1, 2015 by Xyphos

[selfish_meme]

Now see, most of my designs were the standard slow-climb to 10k, I never once considered going super-sonic straight from the runway. *facepalm*

also, I've never thought about using nervas for ascent, I didn't bother because of their weight, low thrust and the fact that I just launched a nuke tug into orbit.

I'm going to try again. Thanks for the inspiration, everyone!

Only do supersonic off the runway with Rapiers, that's because their power band only comes on at around 400m/s, it is usually expensive to go too fast down low but in the case of the rapiers they can have trouble getting over the "mach hump" in their power band at altitude making you dive at full power to gain speed, and then ascend again, wasting even more fuel. At most you would only bring the nose to level at 10km just to go from 800 to 1000m/s before increasing your climb rate again.

[Wanderfound]

That is a pretty cool Spaceplane/SSTO, Wanderfound!

For a somewhat improved version of a similar concept:

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[O-Doc]

If you want some decent range you're going to want to carry some nukes. Most of my designs are now NERVA equipped so that they are useful once in orbit. Here's another Minmus capable Mk3 flyer to demonstate that it is quite possible.

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[selfish_meme]

The Mk3 cockpit is abysmal, and most things put in front of it are very draggy, I have not had a lot of time to test this but it should be much more aerodynamic, you lose a front docking port, but that can go behind the cockpit.

[Jett_Quasar]

This thread has the best example I've seen for an infinite range SSTO. This shows how it can be done - it can go out to Minmus and refuel with the on-board ISRU.

http://forum.kerbalspaceprogram.com/threads/125184-Rolling-Stone-science-SSTO-with-unlimited-range

JR

Edited August 2, 2015 by Jolly_Roger

[Goddess Bhavani]

This thing I built currently only goes sub-orbital though attaining nearly Mach 7 along the way, I'm guessing I'm not flying a correct ascent profile or just plain lacking the intake area required to make the turboramjets accelerate beyond Mach 4 or so, and I just brute force the rest of the way with 4x LVT-45s. Should I go with 12x Rapiers, add precoolers, or try and develop the mixed engine concept further?

Not looking for any sort of interplanetary level efficiency, but just wondering if I can mimic the Pan Am spaceplane in 2001 and send tourists to orbital stations.

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[Vanamonde]

Since this has morphed into a how-to thread, it has been moved to the how-to subforum.

[Dispatcher]

This thing I built currently only goes sub-orbital though attaining nearly Mach 7 along the way, I'm guessing I'm not flying a correct ascent profile or just plain lacking the intake area required to make the turboramjets accelerate beyond Mach 4 or so, and I just brute force the rest of the way with 4x LVT-45s. Should I go with 12x Rapiers, add precoolers, or try and develop the mixed engine concept further?

Not looking for any sort of interplanetary level efficiency, but just wondering if I can mimic the Pan Am spaceplane in 2001 and send tourists to orbital stations.

Really nice work, PK! For non-Rapier SSTOs (planes or otherwise) I've had the most success with a turbojet/ aerospike combination. You may also need to experiment with the type/ quantities of air intakes. The ram scoop takes in a lot and the shock cone seems to reduce drag.

One of my favorite "should have been" spacecraft is the Pan Am Space Clipper. With or without the closed wing, it would be cool!