SSTO LowTech 0.90 Ferram -- doable?

[tklenke]

So I've just spent a week of my life using time best spent otherwise...(damm your eyes KSP!) trying to build a single stage to orbit, horizontally launched space plane capable of launching unmanned (probe), fetching a kerbal from orbit (Mk1 inline) and returning to the runway.

Pretty much all of my designs replicate the X-15, Scaled Composites results. ~60km apo and peri still -400k+ i.e. Can make it to "space" but not to orbit. Tried multiple options, including jet lifters (i.e. white knight/B-52), more SRBs, more intakes, etc. Learned a bunch about using Ferram and SAS to fly some pretty marginally aerodynamically stable designs!

But, I just can't make it happen.

Here's the challenge.

KSP v0.90

Ferram Aerospace

KW Rocketry

Tech tree only through 160 plus Supersonic flight (no Rapiers)

Can it be done?

[LethalDose]

Personally, I don't think it's reasonable to build SSTO aircraft without at least turbojets, which require High Altitude flight, which you've disallowed. Possible, yes, but it's a major hassle. In my book, TJs really are the critical technology that makes SSTO spaceplanes feasible.

With TJ's, you can add small efficient LFO engines (48-7S, 24-77s, or 909s) or O10's to complete the orbit. I know I was to build a low-tech 2-man SSTO in FAR that used 1 TJ, 2 909s, and I believe 3 circular intakes, but that was in 0.24 or maybe even 0.23.5.

PS Expect someone to come in here and get snotty about how it doesn't have to be an aircraft to be an SSTO.

Edited April 19, 2015 by LethalDose

[Alshain]

With the adjustments to the velocity curve that FAR makes, it would be really really hard to make a craft capable of orbital velocities using only basic jets below 40km. I won't say it is impossible, because like LethalDose said, the moment I do someone will come and show how they did it. However, I can safely say it would be very very hard.

However, if all you want is a low tech SSTO and you don't mind dropping the space plane requirement. (Note: probably will not work in 1.0) I'm afraid this is as close as I can get you.

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Edited April 19, 2015 by Alshain

[Hodo]

It is possible, but you would have to give up on the idea of jet power for the SSTO space plane. I would go with a plane powered by highly efficient rockets through its ascent into space. And perhaps basic jet engines for powered landing and take off but not for the acceleration phase.

[UnusualAttitude]

Two standard jets and an LV-T30 will get you to orbit if you get the right amount of fuel on board. Just climb as high as you can on the jets (in this case I reached just over 10k) and light up the rocket. Climb as steep as you can until your apoapsis is on the edge of space then flatten out to gain speed.

This type of ship should be able to do rescue missions up to 100x100 if you fit it with a probe core, but if you wan't to use it as a launcher, then you'd better be damn good at making your probes light and compact.

But yes, lo-tech spaceplanes are seriously limited.

Will polish it a bit and provide download if you like.

Regards, UA.

[UnusualAttitude]

After a bit of experimenting, if you don't mind shedding a few solid fuel boosters on the way, it makes things much more interesting. This got to 100k with a 1.2 tonne payload and nearly 1,000m/s left in the tanks, and there's room to the top (sub-optimal LF-Ox fuel mix). Not strictly SSTO, but all lo-tech.

[cantab]

Making a Basic Jet spaceplane in FAR is tough. You can't even hit Mach 1 on the jets so you need a lot of rocket delta-V, it can be almost as much as for a regular rocket. My approach was to pack big wings to climb as high as I could on the jets, and this is my Basic Jet SSTO, inspired by the Avro Vulcan.

Delivers two Kerbals and up to two tons of cargo to LKO. Takes around 25 minutes to reach 15 km on the single jet, it's a bit underpowered, then the rockets are equivalent to two 909s and 4 48-7Ses - a combination that itself is about the same as one LV-T45 but can be put symmetrically. Fuel routing is designed to minimise CoM shift. One of the toughest things was to get the trim right and keep the nose up through the transonic region - the rearmost parts of the wings are angled up *just* right for this. The wings are all minimum weight too, so this thing needs a gentle hand to avoid snapping them off.

[tklenke]

Two standard jets and an LV-T30 will get you to orbit if you get the right amount of fuel on board. Just climb as high as you can on the jets (in this case I reached just over 10k) and light up the rocket. Climb as steep as you can until your apoapsis is on the edge of space then flatten out to gain speed.

This type of ship should be able to do rescue missions up to 100x100 if you fit it with a probe core, but if you wan't to use it as a launcher, then you'd better be damn good at making your probes light and compact.

But yes, lo-tech spaceplanes are seriously limited.

Will polish it a bit and provide download if you like.

Regards, UA.

Cool. I like the wing as vertical stabilizer...

How much delta-v and or fuel does that thing have at take-off?

[Flayer]

How does it land?

[UnusualAttitude]

Cool. I like the wing as vertical stabilizer...

How much delta-v and or fuel does that thing have at take-off?

LF:1485

Ox:1650

That's about 3,200m/s dV.

I've included a download and an album with the instructions, please read carefully if you're going to use it as this is not a sweet plane to fly. I'm sure you could design a much better airframe, it's just to demonstrate that it is possible with the right amount of fuel and engine choice.

Crzyrndm's Pilot Assistant is strongly recommended for this type of sketchy lo-tech craft (http://forum.kerbalspaceprogram.com/threads/100073-0-90-Pilot-Assistant-Atmospheric-piloting-aids-1-5-4-%28Apr-5%29).

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https://www.dropbox.com/s/grsum459mnaq51u/neo-lithic.craft?dl=0

• How does it land?

• :DWith difficulty ...! Regards, UA.
  

[UnusualAttitude]

I've had a lot of fun refining the concept, if you're still interested...

Solid rocket boosters seem to be the way to go to punch out of the lower atmosphere, and look cool too...

Proof of concept: standard jet/rocket/solid booster hybrid to LKO with 1,000m/s of dV and a crew of two. Non-staged boosters to earn SSTO spaceplane title. Trade range for payload in full-length cargo bay.

Safe re-entry and landing at KSC for full recovery in a career game.

Comes with funky pink lights.

Will now attempt an early career Munar orbit with this: I'll have to practice my free returns...

https://www.dropbox.com/s/0zhzxrpwv3sum3o/turboneolithic.craft?dl=0

[tklenke]

Thanks to hints from you. I made it. Key was big vertical stablizer, move my intakes to rear, pipe fuel from back to front, cheat the SSTO requirement and bolt on some SRBs on the wings (I used Globe I Srbs)

[Jarin]

That's... a lotta fuel lines. What's the strategy there? Or does that cross-linking actually make everything drain evenly, without fuel-balancer?

[tklenke]

That's... a lotta fuel lines. What's the strategy there? Or does that cross-linking actually make everything drain evenly, without fuel-balancer?

roger. No fuel balancer, just plumbing. Otherwise CoM goes backwards and it swaps ends about 20 seconds after main engine ignition.

[Jarin]

Huh... I think I see what's going on there. Everything's feeding towards the middle, then that centered tank drains last, right? I never knew you could countermand the regular rules of fuel flow like that.

[UnusualAttitude]

http://i57.tinypic.com/v4qmg9.png

Thanks to hints from you. I made it. Key was big vertical stablizer, move my intakes to rear, pipe fuel from back to front, cheat the SSTO requirement and bolt on some SRBs on the wings (I used Globe I Srbs)

It seems like you never have too much vertical stabiliser, especially on shorter craft. Although this could probably get away with less, as by the time it gets to altitude and the air runs thin, it's already going like the clappers. Another hint; I wouldn't bother with multiple intakes, as basic jet thrust drops off sharply with speed and will be negligeable long before you run out of air. A single pair of radials may be enough. I only used four circular intakes due to FAR attributing unusually high drag to nosecones for some reason.

[Wanderfound]

Huh... I think I see what's going on there. Everything's feeding towards the middle, then that centered tank drains last, right? I never knew you could countermand the regular rules of fuel flow like that.

With a tri-fuselage jobbie like that, it's usually much easier just to put pairs of core->lateral and lateral->core fuel lines up the front. With that, the lateral engines will start by draining the core rear-to-front, while the central engine drains the lateral tanks rear-to-front. Any weight shift you get is forwards (and is likely slight due to the laterally spread fuel load).