SSTO engine setups

[MKI]

Since the changes, spamming intakes isn't of importance. So whats the setups of engines in the current mode? Until we get the updated engines it seems clustering mutliple engines seems the best way to go.

I have found success with 4 Jets, 2 Rapiers and 2 Nuclears but Its hard to adjust. I need more ideas on engine clusters for SSTOs.

What sort of SSTO engine setups do you use?

[The_Rocketeer]

It depends on how big your craft is, but a single RAPIER is enough for a fairly sizable Mk 2 craft with no extra nacelles (i.e. drag) and a lot of wing.

But I like my SSTOs to look like something sci-fi, so I usually use nacelles with extra engines of some kind. Also shutting off the turbojets and switching to rockets makes me feel BadS.

[GoSlash27]

MKI,

I'm just using jets and plain old vacuum rockets (Terrier or Poodle, depending) for low- tech spaceplanes.

For high tech, it's RAPIERs all the way.

I'm focusing on eliminating drag instead of adding power and it's showing good results for me.

Best,

-Slashy

[tewpie]

Small passenger SSTO (32t): 4 jets and 2 nukes

Medium tanker SSTO (100t): 8 jets, 2 nukes and a skipper

Heavy self-refueling SSTA (250t): 8 rapiers, 8 nukes, 1 rhino

I like nukes

[Highguard]

T-45 makes a great SSTO engine all on its own.

Generally, just work out how much an engine can SSTO on its own and use multiples of them for whatever payload you need.

Jets AND rapiers AND nuke seems really complicated for getting to orbit.

[KerikBalm]

I mostly do just turboramjets and rapiers, I don't take spaceplanes beyond LKO mostly, so rapiers are fine. If I want to take them a bit farther, I'll also stick a nuke on there.

Lower tech- turboramjets and LV-T45s...

If its not a spaceplane: the mammoth is good, the aerospike is good. For a larger SSTO rocket, I may do a pair of mammoths feeding into a central KR-2L, since the KR-2L has better Isp (I'm not actually sure its worth the lower Isp in the atmosphere though, or the deat weight of not using the KR-2L on launch).

Also, nobody siad SSTO rockets can't be airbreathing, so I've found strapping surobramjet nacelles onto a rocket to be viable (they seem to at least pay for their own added mass), and making the gravity turn a little steeper. They can contribute significantly if you do a gravity turn a little steeper and earlier than normal.

Plus they give you more control over where your SSTO rocket lands (and how softly it lands) at the end of the mission

[capi3101]

Myself, I fly FAR, so my advice may not be all that great. I have had great success with a combination of a single Turbojet and a pair of Aerospikes - which in FAR, is sufficient for a plane up to thirty tonnes. In stock, that setup will get you about half that - about fifteen tonnes. I've heard it said that you want somewhere in the neighborhood of 1800 m/s of delta-V for the rocket portion of the flight (to make sure you can get up there, fool around a bit and still have sufficient fuel to de-orbit), and the rocket engine you pick will have a huge bearing on how much plane you can have that's not gas. At a vacuum Isp of 340, the Aerospike offers a good balance of thrust (which you want for that part of the flight), small size, relatively low mass and high efficiency; I can get it to space on 12.5 tonnes of fuel. Only downside is the lack of gimbal, so you have to be a little more careful about how you go aligning them.

I've also had success with Thud engines before instead of Aerospikes. I do have access to RAPIERs in my current save game; I haven't really tried using them due to their lower thrust as compared to a Turbojet at takeoff.

[SpeedDaemon]

I would highly recommend checking Slashy and Val's profiles for some of the SSTO/spaceplane-related threads they've posted in, and reading those.

Those two are almost entirely responsible for my spaceplane ability going from "500 engines and no space for you!" to getting a 190T beast of a Mk3 spaceplane into orbit, and back to the runway (after Valentina dealt with some fuel-balance !fun! during reentry) using only five Rapiers.

[peachoftree]

While technically not an SSTO, my main MK2 setup I use 2 rapiers for planes that are up to 50t and use SRB's to get off the runway. Lots of SRB's. The rationale behind this is that adding a third engine (up to 1.8t for a turbojet) literally outweighs the efficiency gained by using 2 turbos and a conventional rocket (Disclaimer: I use FAR so this may or may not be true for stock) It is also more efficient under FAR because a nosecone on the tail helps reduce transonic drag as opposed to an engine because of the smoother shape.

The plane I have pictured can get 4 crew cabins into space with around 700m/s of delta-v to spare, all on 2 rapiers.

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In thrust we trust!

Edited October 8, 2015 by peachoftree

[Red Iron Crown]

MKI,

I'm just using jets and plain old vacuum rockets (Terrier or Poodle, depending) for low- tech spaceplanes.

For high tech, it's RAPIERs all the way.

This. Though I'll sometimes use the Aerospike instead of the Terrier if I need more thrust in a single 1.25m engine.

LV-Ns can be interesting if you don't want to worry about how much oxidizer to add to the mix, but they're heavy and low thrust plus SSTOs usually don't do enough orbital maneuvering to make the mass penalty worthwhile.

[Wjolcz]

Two Turbojets and Two Swivels got my crew of 6 into orbit with ease.

[FyunchClick]

For my workhorse MKII transporter (hovering up rescuees all over the kerbin system and rotating crew on space stations) I have three rapiers and a single LV-N. I've also flung a huge MKIII based one at Laythe, it's got six rapiers, four whiplashes and two LV-N, based on a mix recommended by goslash27 at another thread. Both are designed to make orbit with kms/s of dV left over for onward journeys.

[GoSlash27]

LV-Ns can be interesting if you don't want to worry about how much oxidizer to add to the mix, but they're heavy and low thrust plus SSTOs usually don't do enough orbital maneuvering to make the mass penalty worthwhile.

True. I have used LV-Ns in conjunction with RAPIERs for my super- economical designs, but the $/tonne advantage isn't very much in the long run and the headaches tend to go up even though it's working with a single fuel.

In a career game, it's worth it to upgrade from TJ/ vacuum rocket to RAPIER (at least for big tankers)... But once that is done the unit cost advantage of upgrading to LV-N vacuum propulsion isn't worth the hassle IMO. It just plain doesn't save enough money to pay for the exercise.

Best,

-Slashy

[peachoftree]

t least in my experience, If you're using a LV-N + RAPIERS than you still should have some oxidiser for when your jets burn out to kick up your Apo. This is because spending the large amounts of time you have to in the atmosphere with the nuke mean that drag losses outweigh the ISP gain.

[MKI]

MKI,

I'm just using jets and plain old vacuum rockets (Terrier or Poodle, depending) for low- tech spaceplanes.

For high tech, it's RAPIERs all the way.

I'm focusing on eliminating drag instead of adding power and it's showing good results for me.

Best,

-Slashy

So in terms of drag important items what should I be thinking about. I sometimes spam intakes for no good and feel that such a decision must hurt my ships drag ratio.

[GoSlash27]

MKI,

If you just want to spam intakes, the shock cone is a good choice. It's one of the most aerodynamic things you can put on the front of a spaceplane. But you don't want to add forward facing surface area just to have more shock cones.

Considerations for drag reduction:

1) Present a clean transition from one part size to another. No sudden changes.

2) Minimal frontal area. Don't build short and wide if you can build long and thin.

3) Avoid surface mounting parts as much as possible. batteries, RCS tanks, struts, etc. And "clipping" them doesn't hide their drag.

4) Wings are a lot less draggy than other parts, so don't be afraid to use them. You exhibit the least total drag when your nose is lined up into the slipstream, so design it to fly that way at Mach 1 and above.

5) Some parts are cleaner than others. ex. The linear RCS port is much cleaner than the RCS block.

Some parts are cleaner when mounted in a certain direction. ex. Landing gear are cleaner when mounted backwards.

Some parts should just plain never be used. ex. The "mobility enhancer" folding ladders are absolutely awful.

If you can get your spaceplane past 360 m/sec in level flight, you can get it hypersonic at high altitude. The objective is to use as few engines as possible to do it. This makes less dead weight for your rockets to push to orbit, and therefore less fuel required.

Best,

-Slashy

[Wanderfound]

There are a few considerations:

* Available tech. RAPIERs always beat normal jets; even without the rocket mode, the higher airbreathing top speed on RAPIERs is a huge advantage. If you don't have RAPIERs, Swivels and Thuds work well for the rocket boost.

* Size of the ship. One jet is plenty for LKO taxis and small satellite lifters. The big Mk3 lifters usually carry around half a dozen jets.

* Intended use. If it's interplanetary, you'll want a nuke and the minimum possible amount of jets. OTOH, if it's a dedicated LKO lifter, then you'll be ditching the nukes and trying to maximise TWR. Interplanetary works very well with a two RAPIER / one nuke combo. The flexible TWR options come in handy when landing on moons or docking; use the nuke for efficiency, but flick the RAPIERs on for a second if you need to wash speed in a hurry.

One ramscoop per engine (or equivalent) is plenty for air supply. Jets will want around 400LF each.

[interface]

Jets and LV-N. Basic SSTO MK2 center body and MK2 side pods attached in line. Side pods have large Manta intakes and surface mount intakes, 2 airbreathing jets each, total of 4 jets. Center MK2 body has 2 LV-N and if I have it unlocked the radiators from KSPI, but you don't really need those they just make it seem more 'realistic' a sequence of parts with a big radiator. They do make the underpowered ship capable of very long burns though, to other planets. Stock SSTO is easier to get to orbit but tricky to not explode from heat if its over powered or one goes to fast to low. Depending on the jets unlocked I have to start the LV-N pretty low or just to kick the plane to over 2000 m/s at around 20-25km. I miss orbit sometimes being to greedy and fearing the heat, but I have to use the 10km to 18km area to get a lot of my thrust. My general rule, that I am not sure is totally correct but seems to be a general convergence of forces, is that 1600 m/s speed anywhere below 16km altitude, the plane is likely to blow up the cockpit or whatever is facing the airflow.

My builds are long and usually delta winged. Build based on the CoL and CoM with the aircraft unloaded of all fuel and monopropellant. Put the tanks near the CoL, use empty tanks in front and behind. Can get away with overloading and having CoM get near CoL as fuel drains if your basicly out of the atmosphere as it gets unstable for aerodynamic flight. Then balance the tanks manually and lock the now empty tanks at the ends. stability on re entry to atmosphere is kinda nice...

Usually the amount of angle on takeoff and landing is an issue with these long thin builds, put some small wings angled down that are just past the angle at which you will hit the LV-N engines, because the little wings will cost a lot less if you over pitch and scrape the lowest and most rearward part off of your ship...

Clip a radial mount at the center line on the closest center body connecting part face, as close to CoM as possible and where CoM will be with typical fuel after orbital burn, and attach a strong reaction wheel unit Enjoy control!

[Right]

LV-Ns can be interesting if you don't want to worry about how much oxidizer

Omg, I never realized this. Thats explains why I never get any decent d/V readouts with those things.