I’ve rediscovered asparagus staging! And have officially given up on SSTO rockets.

[Blaarkies]

7 hours ago, THX1138 said:

I think you could save more time by designing a couple of SSTOs and reusing them with your different playloads. You can put them in your subassemblies section of the VAB. Click the arrow in the top left hand corner of the VAB and then on the green icon in case you don't know where that section is.

^THIS^
I usually aim for building 3 size versions of such vert-SSTOs. The previous one I mentioned is medium(13t payload). Large is however much the Mammoth engine can lift. Small is actually difficult though, and I prefer to just use the medium size and have fuel left over in orbit for the spacestation fuel depot.

It's really fast once you have the perfect recipe in SubAssemblies...but it does take a few test launches before you get that perfect recipe

[Warzouz]

11 hours ago, wumpus said:

Two issues for SSTO rockets:

In career, that's a lot of money you have to have in reserve for your SSTO (sure, you'll get it back, but you have to put up the payment first).

Second, and most importantly: how close to you land to the pad?  With mechjeb, its too easy.  You just hit "land on pad" and collect your 100%.  I'm curious how many players can hit close enough to the pad that they wouldn't benefit from dropped kickback stages (bunched onto two or less decouplers, natch).

SSTO rockets (or S[l]STO, Single liquid Stage to Orbit) have the advantage that you only have to perform one landing.  SSTS/TSTO (single stage to space, two stage to orbit) allows recovery, but requires two landings (a docking isn't faster than a landing.  Even thought they will be *very* close).  This makes them inconvenient to fly, if easier to make.  Maybe just use stage recovery (or flight manager and don't bother getting the first stage into orbit).

For the cash : Since dV was reduced from 4500 to 3200, SSTO aren't much more expensive than a regular rockets (I was quite surprised when I build a regular launcher for my space station. I had to use very few engine and many boosters to get the price significantly down.

As you progress in the campaign you get more and more cash as you start using heavier and heavier payload. BUT recoverable SSTO rockets need quite some tech (batteries, probe core, efficient engines, big control wheels...) you may not be able to use that from the start. I never had any issue with cash.

As for landing, I never aim for KSC, I always target the east sea. In the end, my average recovery is 20 to 70km from KSC with a 97% value recovery. Landing a SSTO is not a precision manoeuvre.

Check my table below. Except for the 15T Payload my average cost per T (after average recovery rate) is from 360 to 440 funds. And if you don't revoer the rocket the launcher maybe twice the price, not 10 times more.

[Warzouz]

10 hours ago, gchristopher said:

Agreed. The 1.0 aero changes made fitting things in cargo bays almost mandatory for spaceplanes, while you can much more easily handle odd-sized payloads on rockets using fairings. Prior to 1.0, SSTO spaceplanes using airhogging were by far the most cost-efficient option. I don't know what wins in 1.1.3.

SSTO space planes are still cheaper than SSTO rockets (recoverable of course). The issue is that they aren't scalable. Once you have a flying plane, you can't just double every thing to get a double payload. You can for SSTO rockets.

It took me a lot of time to tweak my recoverable SSTO rocket. But when I did that, I got the whole family of launcher (11 of them) very quickly.

As on the subject : Since dV LKO requirement went from 4500 to 3200m/s the gain from using asparagus is much less important than it was back in beta.

Asparagus are more mass efficient but less cost efficient.

What is the real gain in launcher mass % (should be easy to get) and in funds (harder, depends on design) ? for a 3200m/s rocket. As for SSTO, it's also easy to compare in mass, but not in funds as a SSTO don't care about using the most expensive parts (they get them back, or 97%)

PS : OK, sadly, time to work now...

Edited July 1, 2016 by Warzouz

[magnemoe]

3 hours ago, Warzouz said:

SSTO space planes are still cheaper than SSTO rockets (recoverable of course). The issue is that they aren't scalable. Once you have a flying plane, you can't just double every thing to get a double payload. You can for SSTO rockets.

It took me a lot of time to tweak my recoverable SSTO rocket. But when I did that, I got the whole family of launcher (11 of them) very quickly.

As on the subject : Since dV LKO requirement went from 4500 to 3200m/s the gain from using asparagus is much less important than it was back in beta.

Asparagus are more mass efficient but less cost efficient.

What is the real gain in launcher mass % (should be easy to get) and in funds (harder, depends on design) ? for a 3200m/s rocket. As for SSTO, it's also easy to compare in mass, but not in funds as a SSTO don't care about using the most expensive parts (they get them back, or 97%)

PS : OK, sadly, time to work now...

Not only did the dV requirements go down but we got stronger and more efficient engines, joints also become stronger, back in before 0.9 trying to put more than two orange tanks on top of each other and you had to brace them, having an wide rocket helped reduce load. In 1.0 an long and thin rocket is more stable and has less air resistance. 
Crossfeed is nothing I would use outside of very heavy rockets or stuff like eve accent. 

One interesting thing about KSP is that compared to real life the second stage tend to be small, this because of the low orbital speed and low attitude for orbit, 
Typical rocket of mine, first stage has 2400 m/s and takes me to 1800 m/s second stage has 600 m/s, Falcon 9 first stage also reach 1800 m/s but second stage does 7km/s. 

Just tested an nose first SSTO rocket, worked pretty well except that speed in lower atmosphere was a bit high, could not use droge parachutes until 3 km attitude. 
Will need airbrakes, an equipment bay works well as an high speed airbrake, nice for doing corrections it also looked like opening it protected the tail fins from overheating, 

[Warzouz]

I tend to let my second stage over 1000m/s or they become too small. My first stage is helped by boosters for taking-off.

[wumpus]

97% recovery makes it sound hard to improve costs by adding kickbacks, but SSTO rockets tend to be much bigger than two stage.  Unfortunately the American holiday this weekend won't let me play much KSP, so who knows if I'll check this or not.

[evileye.x]

I dont use asparagus at all, because I try to play semi realistic way. Usually my core stage have 2500 vacuum dV - it is usualy enough to have apoapsis in space and upper stage 1000-1100. I use SRBs as TWR boosters on lift off, thrust limited to have 1,6-2,0 (or even less)  TWR on pad

[DaMachinator]

The Caduceus autonomous lander and transfer stage use a recoverable SSTO lifter...

1.25m decoupler --> 1.25m fairing --> 1.25m SGS --> 1.25m>2.5m adapter (I think it's the one with fuel in it) --> two orange tanks --> Mainsail.

The Caduceus can land on Moho (unless I broke something when I made slight adjustments to the layout of the probe), leaving the lifter in an 80x80 parking orbit with enough fuel to deorbit.

• Sepratrons, drogues, and parachutes included for ease of landing.
• Landing legs (probably) not necessary, and therefore not included.
• Reentry tested with full stock heating. Gyration during reentry is normal.

https://kerbalx.com/DaMachinator/Caduceus

Edited July 1, 2016 by DaMachinator

[Sereneti]

i had build an rocket SSTO because it is on the long therm cheaper as an disposable rocket.

the diference between an SSTO-Rocket and a disposable rocket was +20k on the SSTO vehicle.
(same payload same orbit.)

+20k by 100k ground-costs...

i  only have to sucsesfully land it on more than 1/5 the thime, to safe money.

 if i partialy destroy the rocket during the landing, i dont care.
- even to save the engines and some parts bring back a lot of money. 

[KerikBalm]

11 hours ago, Warzouz said:

SSTO space planes are still cheaper than SSTO rockets (recoverable of course). The issue is that they aren't scalable. Once you have a flying plane, you can't just double every thing to get a double payload.

Well... thats not entirely true... you can make a large design and scale the fairings, scale the fuel load... remove engines/engine+fuel pods (leaving lots of wing, which is generally OK)... you can add more engines (leaving a high wing loading, which can be OK). You can even have small wings on each engien pod to help keep wingloading constant... but that drives up part count rapidly

I also made "strap on" SSTOs for this purpose... just add a few more to a spaceplane to increase its payload capacity...

Heck I can even add them to a payload (radially attached) plus some recoverable RATO boosters to get payloads to vertical launch and then transition to horizontal flight... although with my current "strap on" designs that would have a very high wingloading and rely on a lot of engine power... but its still scaleable.

The problem is ... each detachable SSTO needs to land seperately... doing 4 landings for getting 1 payload to orbit is tedious:

also, I find it generally works better if the payload itself is an aircraft:

^Thats a non-airbreathing duna spaceplane... it was carried aloft with 4 of those strap on SSTOs

2 just drifted off before I took that pic http://i.imgur.com/LoHupbN.png

The "payload" which provided most of the wing: http://i.imgur.com/bA3g4rS.png

An earlier example:

Revised "payload": http://i.imgur.com/LPusxk4.png

"Scaled up" for a larger payload: https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xat1/v/t1.0-9/11219454_10103669579435223_4404198240254229192_n.jpg?oh=a076c2b4f5bc9aec9568f1032f8dd4d7&oe=57FF70CE&__gda__=1476316684_96262c5c81f6bf21767f6f143e537702

the RATO boosters for vertical launch, that land on the runway (also madea  variant using the LES and radial chutes): https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xfl1/v/t1.0-9/11057974_10103669579530033_499678238987866084_n.jpg?oh=219aab34ee20845c78f2a8bad3dbca5e&oe=5835C729&__gda__=1475173996_32a88f0ccff8e68bad5bdf88aca5c144

 

 

 

23 hours ago, gchristopher said:

Agreed. The 1.0 aero changes made fitting things in cargo bays almost mandatory for spaceplanes, while you can much more easily handle odd-sized payloads on rockets using fairings. Prior to 1.0, SSTO spaceplanes using airhogging were by far the most cost-efficient option. I don't know what wins in 1.1.3.

Well... It is easier with rockets, but I disagree that cargobays are "almost mandatory"

 

 

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

http://i.imgur.com/2du0xio.png

 

[Brainlord Mesomorph]

14 hours ago, Warzouz said:

Check my table below. Except for the 15T Payload my average cost per T (after average recovery rate) is from 360 to 440 funds. And if you don't revoer the rocket the launcher maybe twice the price, not 10 times more.

Hi guys, sorry I dropped this thread, real-life got in the way.

I’m glad you responded, because I totally agree with you (at least I use to) but here’s the thing, we’re fooling ourselves a little bit with those numbers.  I built myself a series of SSTO rockets very (very) much like your Cygnus series. And my point is: That if you play a tough game (and don’t F9 too often) then those numbers don’t hold up. You’re comparing recovering your rocket to not recovering your rocket, as apposed to not recovering a much cheaper rocket.

Lets take your 100 tonne lifter, with 97% recovery (which you can’t really get on average) it costs 36,000 funds per launch right?  But it costs 181,000 on the pad. Now can I build a stripped down disposable multi stage 100 tonne lifter for about 75,000. (actually I like it when they are about 100m/s shy of orbit)

Lets say you have five perfect launches of your booster and then you crash one (you named him Brad, and then you totaled him ) Over 6 launches your costs now go up to 60,000 per launch. Suddenly my 75,000 Bic pen booster doesn’t look so bad.

It only really costs 15,000  20,000 per launch (over the long haul) to just toss the booster.

And that’s my point.

 

[Der Anfang]

Personally, I still asparagus stage mainly just because it looks fuggin cool and it's fun watching those spent stages fly off the sides of the rocket and back down to the ground.

I thought Asparagus staging was efficient? Structurally efficient, that is... more stability. Plus, it's a must have for Eve landers in particular.

Edited July 1, 2016 by Der Anfang

[Alshain]

The use of asparagus declined because v1.0 aerodynamics made it unnecessary and wasteful.  You don't need an SSTO, but you don't need asparagus either.   A two stage rocket with any necessary radial SRBs is just fine.

SRBs are cheap, in fact the decoupler you will use on them is often more expensive than the SRB, so avoid larger symmetries (8x) and instead just go with larger boosters.  The upper stage engine will likely be relatively cheap as well, that just leave 1 expensive engine.

Edited July 1, 2016 by Alshain

[Violent Jeb]

[redacted, done]

Edited August 16, 2016 by Violent Jeb

[Der Anfang]

3 minutes ago, Violent Jeb said:

Can you expand upon this?

Asparagus may not be entirely necessary for orbits, but sending some larger crafts interplanetary and I have no way how i would cram potential without asparagus staging or orbital refueling (a luxury i do not have the time for). The Joolian M which was a mining vessel (guess where) had almost 18000 dv on the pad and at least 20% of that I attribute directly to creative asparagus staging.

Asparagus staging has the added benefit (on atmospheric bodies) that as your TWR requirements decrease with atmosphere, falling asparagus stages keep the TWR dropping in step (as to not have too great of drag losses).

Not only that but IMO having 5 engines and tanks which shed 40% of their dry mass as they empty each set of tanks remains more efficient than hauling a single larger tank with excess TWR from a progressively oversized engine, further into space. I can see where a dozen engines might run into more substantial drag, but not a configuration with a reasonable number of stages. (edit: I see now you mentioned this in your edit)

Is Asparagus just OP and more costly, or is there something i'm missing?

I agree completely. A single "pencil" rocket just won't do for those 80-100 tonne loads when launching off of Kerbin. Sometimes I just don't want to go modular and I want to go big. It's things like this that require asparagus, primarily for the reasons that you had just listed, but also for stability. If you were "pencil" (or serial) staging, your rocket might have a higher chance of flipping, or wobbling. And I know how much a payload inside fairing hate wobbling. Even if you strut the hell out of the payload.

[Alshain]

1 minute ago, Violent Jeb said:

Asparagus may not be entirely necessary for orbits, but sending some larger crafts interplanetary and I have no way how i would cram potential without asparagus staging or orbital refueling (a luxury i do not have the time for). The Joolian M which was a mining vessel (guess where) had almost 18000 dv on the pad and at least 20% of that I attribute directly to creative asparagus staging.

The discussion is comparing SSTO to Asparagus staging, the context is that we are talking about getting to orbit, not interplanetary travel.

1 minute ago, Violent Jeb said:

Asparagus staging has the added benefit (on atmospheric bodies) that as your TWR requirements decrease with atmosphere, falling asparagus stages keep the TWR dropping in step (as to not have too great of drag losses).

As does dropping radial boosters and a the first stage of a two stage rocket.  Furthermore, an asparagus stage is massively expensive due to the liquid engine, while an SRB is cheap.

7 minutes ago, Violent Jeb said:

Not only that but IMO having 5 engines and tanks which shed 40% of their dry mass as they empty each set of tanks remains more efficient than hauling a single larger tank with excess TWR from a progressively oversized engine, further into space. I can see where a dozen engines might run into more substantial drag, but not a configuration with a reasonable number of stages.

Who said anything about a single tank?  I said two stage rocket.  My two stage rockets also shed, more than 40% of their dry mass.  (Note: When I say "two stage", I mean on the center stack, that doesn't include the SRBs).

9 minutes ago, Violent Jeb said:

Is it just OP and more costly, or is there something i'm missing?

No, that is the primary reason.  It's massively more expensive.

4 minutes ago, Der Anfang said:

I agree completely. A single "pencil" rocket just won't do for those 80-100 tonne loads when launching off of Kerbin. Sometimes I just don't want to go modular and I want to go big. It's things like this that require asparagus, primarily for the reasons that you had just listed, but also for stability. If you were "pencil" (or serial) staging, your rocket might have a higher chance of flipping, or wobbling. And I know how much a payload inside fairing hate wobbling. Even if you strut the hell out of the payload.

Not if you know how to build it right.  My rockets practically fly themselves.  You launch them, you set the gravity turn, you turn off the SAS and sit back a drink a cup of coffee till you reach target Ap.  Also, I have a 100 ton lifter right here that does just that (note: the payload is just an example for the screenshot, obviously not 100 tons).  This one costs 147,000 funds, not including the launch clamps and lighting which are recoverable and of course that is just the cost of the lifter.  It's been tested to 100 tons at 100km parking orbit.

 

[Corona688]

17 hours ago, Warzouz said:

SSTO space planes are still cheaper than SSTO rockets (recoverable of course). The issue is that they aren't scalable. Once you have a flying plane, you can't just double every thing to get a double payload. You can for SSTO rockets.

There's spaceplanes in this thread which literally look like several smaller spaceplanes bolted together.  There's no reason you can't do that in principle as long as you're willing to make it look really strange.

Edited July 2, 2016 by Corona688

[Van Disaster]

If you build a (fixed probably ) canard spaceplane and get the aero balance right you can just keep stretching the body in the middle, which is where the payload bay ought to be. HOTOL Spaceplanes aren't all SSTO either, mind, I've built droptanks with intakes on the front & jets on the rear before, but these days the difficult bit is usually 25km->45km, so a disposable boost stage for there is pretty helpful. Dragging it up there only consumes jet fuel which is no big deal.

Edited July 2, 2016 by Van Disaster

[Warzouz]

9 hours ago, Brainlord Mesomorph said:

I’m glad you responded, because I totally agree with you (at least I use to) but here’s the thing, we’re fooling ourselves a little bit with those numbers.  I built myself a series of SSTO rockets very (very) much like your Cygnus series. And my point is: That if you play a tough game (and don’t F9 too often) then those numbers don’t hold up. You’re comparing recovering your rocket to not recovering your rocket, as apposed to not recovering a much cheaper rocket.

In my table, I compare the different recovery of my rocket, of course. I don't compare it to a fictive rocket. I'm not telling that by landing a SSTO rocket you gain (no recovery value - 97% average recovery value), I just stating the average cost of a launch.

In my 1.1 campaign, I don't use SSTO rockets, my launches are more expensive, not doubt about that (around 1000 per T, maybe more). As for crashing the recover rocket, that happens but quite rarely. Even if the rocket fall, you still get most of it.

I quite don't get your argument : every mission failure (partial or total) cost if you don't use reload. When you forget something, you need another mission to bring it. That costs a lot too.

Sure recovering a rocket is an additional part of the mission but that's not harder than landing a SSTO space place on the runway.

[Warzouz]

8 hours ago, Der Anfang said:

I agree completely. A single "pencil" rocket just won't do for those 80-100 tonne loads when launching off of Kerbin. Sometimes I just don't want to go modular and I want to go big. It's things like this that require asparagus, primarily for the reasons that you had just listed, but also for stability. If you were "pencil" (or serial) staging, your rocket might have a higher chance of flipping, or wobbling. And I know how much a payload inside fairing hate wobbling. Even if you strut the hell out of the payload.

@Alshain is true. You can send a 100T "pencil like rocket" to space, even worstly shaped payloads than his screenshot. Wobble can be contained with struts and mostly engin gimbal reduction. Even fins control has to be reduced by default. A well designed rocket should mostly fly by itself. If you have to force it eastward, that mean you thrust is too high. Don't turn east, reduce or stop thrust for a moment, then burn again.

By doing that, you rocket will always keep straight and won't wobble.

Well, that not OP subject related though...

[GoSlash27]

14 hours ago, Der Anfang said:

I agree completely. A single "pencil" rocket just won't do for those 80-100 tonne loads when launching off of Kerbin. Sometimes I just don't want to go modular and I want to go big. It's things like this that require asparagus, primarily for the reasons that you had just listed, but also for stability. If you were "pencil" (or serial) staging, your rocket might have a higher chance of flipping, or wobbling. And I know how much a payload inside fairing hate wobbling. Even if you strut the hell out of the payload.

Der Anfang,

 While I agree with this, I personally never have a need to launch 80-100 tonne payloads. I'm big into modular orbital assembly. The biggest thing I've ever needed to lift is my orbital fuel storage tank, but in this case the rocket *is* the tank.

 Being lazy, I simply design a disposable 2 stager for the payload and leave it at that. I know that I could save a little cash by utilizing asparagus staging and partial/ fully recoverable designs... but I never find myself strapped for cash and I don't like to waste a lot of time recovering parts.
 The exception is SSTO spaceplanes, which I use for crew and fuel. In this case, the long term cost savings on these "delivery truck" missions is so dramatic that I can't pass it up. Plus the advantages of improved safety for the crew and avoiding orbital clutter (why lift an entire tank to orbit when all I'm using is the fuel?)...

YMMV,
-Slashy