RIP SSTO, long live SSTO?

[Red Iron Crown]

Isn't it still that way in stock? If not, I had no idea. Besides, if you're got to move a dozen Kerbals, it's a lot easier with the units docked so they don't drift too far apart or, worse, into each other .

But anyway, you'll probably still have to refuel the thing in Laythe orbit, and you need a port for that.

It is no longer that way in stock, internal crew transfer was added a couple of versions ago.

Wasn't really suggesting that docking ports aren't useful, they are for the very reasons you mention (and crew transfer is a lot more convenient and less time consuming with them).

[Temeter]

Honestly, SSTO rockets were always superior, especially when it came to FAR or new stock. It's not hard to achieve 3.5k dv and bringt it down with some chutes.

[ajburges]

To be useful for rotating crews, a spaceplane needs a docking port. If you put this on one end of the fuselage instead of using an inline port, you can hook a transfer tug to the spaceplane once in orbit and take it wherever. Then you don't need a refueling station in LKO. Putting the tug on the nose is probably best, so you can aerocapture at both Jool and Laythe using the tug as the heavy, shielded thing in front and the spaceplane's wings in the back pointing the right direction through the atmosphere. Once at Laythe, the spaceplane just needs enough fuel to deorbit and then, if you don't come down in the right place, fly however far to the designated LZ where it will be refueled via ISRU. Thus, you can send the spaceplane out with essentially empty tanks, making the transfer tug's job easier, and maybe top it up with a little leftover tug fuel as needed prior to descent.

Inline? Bah!

One of these days I'll finish my interplanetary sled for Mk2 space planes. A beautiful ring with nukes and an umbilical! Not sure what I'll do for aero braking, but at least I put docking ports ahead of space plane CoM so heat management and pitch authority are the only issues to address.

[Wanderfound]

SSTOs are still the way to go for ferrying kerbals and supplies to stations in LKO. For large structures and assemblies, you don't save very much by building a big complex SSTO vs. a disposable lifter.

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LF √0.8 x 5731 = √4584.8

O √0.18 x 5539 = √997.02

MP √1.2 x 4 = √4.8

Total cost = √5586.62 for a fully-loaded Rockomax 64 plus accessories in orbit (not including the cost of the cargo).

Obviously still some optimising to be done, though; excessive LF reserves at landing.

Edited May 27, 2015 by Wanderfound

[AbacusWizard]

I'm fond of the Arthur C. Clarke approach for small payloads such as crew or supplies:

• SSTO spaceplane to get payload from surface to low Earth orbit

• orbital rendezvous and dock; transfer payload to interplanetary cargo freighter that is not intended to ever land

• freighter maneuvers into transfer orbit to other planet

• once in orbit around other planet, rendezvous and dock with another SSTO spaceplane already in orbit

• transfer payload to SSTO spaceplane, de-orbit, and land on planet surface

High initial cost to built a big interplanetary cargo freighter and move a spaceplane to the other planet, but everything's reusable, so once the infrastructure's in place you can move people and supplies from planet to planet for only the cost of fuel (and with an ISRU outpost on Minmus, that costs only sunlight).

[GoSlash27]

I'm fond of the Arthur C. Clarke approach for small payloads such as crew or supplies:

• SSTO spaceplane to get payload from surface to low Earth orbit

• orbital rendezvous and dock; transfer payload to interplanetary cargo freighter that is not intended to ever land

• freighter maneuvers into transfer orbit to other planet

• once in orbit around other planet, rendezvous and dock with another SSTO spaceplane already in orbit

• transfer payload to SSTO spaceplane, de-orbit, and land on planet surface

High initial cost to built a big interplanetary cargo freighter and move a spaceplane to the other planet, but everything's reusable, so once the infrastructure's in place you can move people and supplies from planet to planet for only the cost of fuel (and with an ISRU outpost on Minmus, that costs only sunlight).

AbacusWizard,

I'd always attributed that concept to the NASA Space Task Group. http://www.hq.nasa.gov/office/pao/History/taskgrp.html

Of course, Heinlein often talked about the same concept in his books as well. I wonder who actually thought of it first?

Sorry for the sidetrack. Yeah, this is the optimal way to run a railroad IMO.

Best,

-Slashy

[Hotaru]

In my career mode currently I have two classes of SSTO (which I posted here in the SSTO showcase thread if anyone's curious). One is a four-passenger spaceplane, the other is a 2-ton-to-LKO reusable rocket. Both are pretty much 100% stock (there are a couple of mods involved but they don't affect the ships' performance at all), and both have been extremely profitable.

The spaceplane costs 35,428 funds per unit and 952 per flight in fuel costs, for a total cost of 1,123 per Kerbal to orbit (including the cost of the ship amortized over ten flights). That's compared to 42,864 per flight (14,288 per Kerbal) for the expendable rocket it replaced--an order-of magnitude reduction in costs.

The rocket costs 33,933 per unit and 5,275 per flight, for a total of 4,334 per ton to LKO (again amortized over ten flights). Compared to 25,900 per flight (12,950 per ton) for a comparable expendable lifter. Not quite as dramatic an improvement but still better by a factor of about three.

Whether the benefits scale up to heavy lift vehicles or not I don't know (I have a 3.75-meter reusable lifter under construction but it hasn't flown yet), but I bet they do. Wanderfound's SSTO above costs 176,000 funds or so (not sure how much is fuel and/or payload) which is about twice the cost of my current expendable tanker ship (which is basically just a Jumbo tank with an engine, probe core, and docking port, launched by an expendable lifter), but being fully reusable I expect it would make up the difference after three or four missions at the most.

I don't think SSTOs are dead in any sense!

PS. Actually it occurs to me the rocket is not 100% stock, it uses Procedural Fairings, which are so essential I often forget they're not stock. It would perform about the same with stock fairings though, just wouldn't look as good.

Edited May 27, 2015 by Hotaru

[AbacusWizard]

AbacusWizard,

I'd always attributed that concept to the NASA Space Task Group. http://www.hq.nasa.gov/office/pao/History/taskgrp.html

Of course, Heinlein often talked about the same concept in his books as well. I wonder who actually thought of it first?

Sorry for the sidetrack. Yeah, this is the optimal way to run a railroad IMO.

Best,

-Slashy

I think I first read about it in Clarke's The Exploration of Space, published 1951 (although my copy is an updated version from the early 1960s; not sure how much was changed). It's a great book; I was basically using it as a user manual for KSP when I first started playing a year ago.

[G'th]

The most important cargo for an SSTO (particularly of the spaceplane variety) is in Kerbals. This is evident just in the simple fact that all of all the parts that can hold Kerbals, the spaceplane parts are the only ones that can hold a significant amount of them.

Using SSTO's for anything else is mostly just pushing the boundries for the funsies more than it is a practical solution.

[Maukse]

I have a *budget* mkII ss spaceplane able to lift almost 20% weight ratio (5tons) or 6 kerbals + monoprop & 200 spare m/s DV for rendez-vous & docking.

By budget, I mean highest tech= turbojet.

So for me MkII spaceplanes are still a very interesting way to lift crew & small probes to orbit.

I dislike mkIII - looking ugly, too many parts, so I've never really tried to make these madness fly !

[KerikBalm]

The most important cargo for an SSTO (particularly of the spaceplane variety) is in Kerbals. This is evident just in the simple fact that all of all the parts that can hold Kerbals' date=' the spaceplane parts are the only ones that can hold a significant amount of them.

Using SSTO's for anything else is mostly just pushing the boundries for the funsies more than it is a practical solution.[/quote']

Confirming, drag and drop into a large aeroshell, place a few struts, with a very cheap cost to get one's payload into orbit is impractical.

I direct you to post #8 of this thread.

Ever since unlocking turbojets in career mode, my space program has become SSTO only.

And I've recently added nuclear ferries and ISRU, so I've got a fully fledge STS now

[Captain H@dock]

The most important cargo for an SSTO (particularly of the spaceplane variety) is in Kerbals. This is evident just in the simple fact that all of all the parts that can hold Kerbals' date=' the spaceplane parts are the only ones that can hold a significant amount of them.

Using SSTO's for anything else is mostly just pushing the boundries for the funsies more than it is a practical solution.[/quote']

I don't exactly agree. Fuel is at least as important.

In 0.90 (I'm not there yet in 1.02) I've used a SSTO plane for both refueling and crew ferrying to/back from LKO, because these are cheaper and simpler with planes. Since (mk2 and mk3) crew cabins and tanks are interchangeable parts, the same design should do (I even made a quick tool to switch these parts in a craft file). The only difference is that the crew one will be heavier on landing, which might require better piloting skills.

From there you just conventionally launch all your payloads empty (with no fuel), which makes them a lot lighter. Transfer tugs go back and forth between Kerbin and other body's orbits, where re-usable landers (which SSTO to the body surface and back to orbit) are waiting for them. This allows you to standardize a lot of your fleet when going inter-planetary. After some time, you'd probably only lift fuel and kerbals (SSTO) as well as the occasional outpost/station modules (conventional).

Sadly, I don't think you can do that until you've milked at least one moon for science, which is a shame for my current 1.0.2 career*. Also, payload fraction seems to be lower, which means I'll require more trips / bigger planes. It's a shame since on 0.90 my 30 tonnes mk2 design allowed me to bring 60% of an orange tank / 20 kerbals for a cost of about 2000 (flight time of about 10/15 mn) with a 'reasonable' look.

* It makes sense from a technological point of view, but these rescue in Kerbin/Mun orbit missions would be so much more profitable with a SSTO and a Kerbin <-> mun pod. I think it's possible on low tech, but the crew/fuel payload would be too small to make it practical.

Edited May 27, 2015 by Captain H@dock

[Warzouz]

In beta 0.9, I played the "Science" gamemode : no cash, so no real use for SSTO.

But as in 1.0, I play the regular Carreer gamemode and rocket SSTO can orbit payloads for quite a bargain price.

I've designed my own set of SSTO rocket stage..

I'm using them since my second minmus mission. They are some kind of minigame : tweaking reentry paramters right to get the max cash back. I like that.

[oversoul]

This is an interesting discussion.

I generally avoid SSTO anything because of its complexity, and it doesn't seem like a good risk-reward setup for my career mode. That is of course probably because I use StageRecovery. But every now and then I like to play with the concept for fun and to break up the money grind, science grind monotony.

Anyway I read some of the remarks in here and was inspired to build a first stage that enough smack to throw a small rescue drone into LKO, then deorbit itself and land using brakes and chutes. The mission was to rescue a crewman from Mun orbit. The rescue drone only has a full weight of four tons, and after a lot of tinkering in the VAB I ended up with something ridiculously large for throwing a 4t payload (3.8t actually). I ended up settling with the Mainsail and a lot of fuel. Here it is on the way back, passing over the desert peninsula west of KSC. I ended up landing okay for a 94% refund about 85km away from the KSC, just west of the mountains which I was trying like hell to miss, brakes out whole time. The rescue drone flew onwards and rescued the stranded kerbal and returned home with something like 100dV to spare after aerobraking twice.

the SSTO rocket on descent to the KSC continent

the rescue drone payload, 3.8t

On a related note, it's interesting to follow this technology IRL. Elon Musk thinks cost to LEO can be reduced by up to 90% with reusable first stages. 90 percent!

Edited May 27, 2015 by oversoul

[Hotaru]

Which way is it going in that screenshot? Nose-first or tail-first? Mine always reenter tail-first, with the airbrakes at the top to keep them stable going backwards, but mine don't have chutes. Did you do it that way, or reenter nose-first and then use the chutes to turn it around for landing?

[Pecan]

BTW, I made this to clear things up for people:

http://i.imgur.com/l03WwUv.png

As everyone has been saying, don't say "SSTOs are dead" and only mean spaceplanes (and those aren't dead anyway, but we've covered that).

I despair that so many people still can't tell the difference, even in this thread.

[Moon Goddess]

+rep, but maybe a picture of a plane WITH drop tanks in the cyan?

And while looking for that I found this cool article.

http://theaviationist.com/2013/09/18/fuel-tanks-se-asia/

[magnemoe]

To be useful for rotating crews, a spaceplane needs a docking port. If you put this on one end of the fuselage instead of using an inline port, you can hook a transfer tug to the spaceplane once in orbit and take it wherever. Then you don't need a refueling station in LKO. Putting the tug on the nose is probably best, so you can aerocapture at both Jool and Laythe using the tug as the heavy, shielded thing in front and the spaceplane's wings in the back pointing the right direction through the atmosphere. Once at Laythe, the spaceplane just needs enough fuel to deorbit and then, if you don't come down in the right place, fly however far to the designated LZ where it will be refueled via ISRU. Thus, you can send the spaceplane out with essentially empty tanks, making the transfer tug's job easier, and maybe top it up with a little leftover tug fuel as needed prior to descent.

Spaceplanes are IMHO the best way to go for reusable Laythe landers, PROVIDED you give them good STOL and off-road capabilities and find a good LZ for them. Their advantage over conventional landers is that heat shields go away eventually and can't be replaced in the field. Plus it's easier to hit some of the smaller islands with a plane than a lander

True, good idea with the front docking port, I would probably just add an drop tank on it as it would give the plane the vacuum dV it need, sending to Minmus refuel and drop close to kerbin for gravity boost to Jool is another idea.

I have just tested one ssto and its not suitable for laythe.