I love building asparagus rockets in KSP but don't see them much in real life.

[Odo]

The number of engines has nothing to do with pogo oscillation. Apollo 6 had it, and Apollo 13 had it pretty seriously but nobody ever talks about that because Apollo 13 had other issues during the flight that got more attention from the press, and pogo oscillation has been a known problem on earlier (one engine) rockets as well.

There was only one case of an N-1 where pogo oscillation was a problem and ironically that was the most successful N-1 flight (in all fairness it might have occurred on the other flights if they didn't blow up first). The other flights ended even earlier, because it is simply impossible to get reliability out of something that uses 30 engines, and because there were some serious engineering problems with the N-1.

Edit: as you mentioned, having 30 engines doomed the N-1. But there's little relation between 30 engines and pogo oscillation

As far as I know the reason the N1 was stomped into the dust was because the vibrations from those 30 engines shook and brutally ripped apart all of the piping inside the N1. It used a lot of piping. Which led to engineering disasters when the thing started moving.

[kalor]

The only rocket I personlly have seen info on that uses "asparagus staging" doesn't use the...shall we say, excessive... amounts that you see in KSP. The Falcon Heavy uses the same principle, but only two liquid fuel/oxygen boosters, the fuel tanks of which feed the primary engine until they stage. As someone else stated earlier, more moving parts and pieces means less reliability, as a general rule.

Also, as a second point, modern, real world space agencies are putting MUCH lighter craft up than we are. Apollo 13, with the lander and command module, was a total of approximately 48 tons. And that had to go up on a Saturn V, one of, if not the, heaviest lifting rocket system seen the world over at the time. The payload capacity of a Saturn launch system is ~50 tons to TLI. Players here fairly regularly are lifting much more than 50 tons to FAR further than TLI ranges, though most of the potential delta-V is spent in launch, the orbital portion is minute in comparison.

Aerodynamics certainly plays a part as well, as the big, wide lift plates and asparagus systems I have seen *should* have VERY serious issues making gravity turns, meaning that the required delta-V for them increases as they fight gravity directly more than their smaller counterparts. In the real world, this means more difficulties in the launch vehicle, couplings for the payload, and, the all-important budget. Currently, we have no budget constraint in building our massive ships, whereas, in real life systems, the budget has to be justified to someone - board of directors, budgeting committees, investors, and so on.

So to make it simpler... yeah, its far simpler to build multi-stage rockets in the real world, due to many factors, than it is to asparagus stage.

[rakutenshi]

In KSP we have Asparagus staging because we also have the tall rocket hula dancers.

In RL, it's possible to build rockets that connect at more than one simple node point between stages, fuel tanks and engines, so the tall skinny more aerodynamic rockets are far preferred over big squat pancake rockets.

Ferram does help with this but once they do their aerodynamics pass, I believe you'll see the popularity of asparagus staging lifters drop significantly.

Also, on the note of random engine failures and escape systems. You only need an escape system if you can't press the 'revert button', so I'd think that they'll eventually add a 'hardcore' flag to the career mode start window, removing the revert button (possibly allowing you to revert before liftoff, i.e. scrub a launch), but this is just my random guessing and based on nothing other than my personal 'feel' for the way the game is going.

[Armchair Rocket Scientist]

A proper way to penalize asparagus staging in KSP, though one that would probably be somewhat complicated to model, would be to conserve the momentum of the fuel as it drains. As the fuel drains counterclockwise out of each liquid booster, the rocket will pick up clockwise spin to conserve momentum in the system. Then the primary issue with an asparagus monster isn't drag (though it is a fairly big factor), but the fact that your rocket is spinning like mad as you try to pilot it into orbit; this would make gravity turns particularly nasty, since it could lead to the rocket's roll combining with the pitch-over movement to send it off course.

Of course, this is one of the larger problems in real life.

In real life (and hopefully in future versions of KSP) rockets with multiple gimbaled engines can point them in opposite directions for roll control. I would imagine the roll authority that would provide would easily counteract the torque from moving fuel around (although steering losses would eat up some of the delta v savings).

[Vector]

As far as I know the reason the N1 was stomped into the dust was because the vibrations from those 30 engines shook and brutally ripped apart all of the piping inside the N1. It used a lot of piping. Which led to engineering disasters when the thing started moving.

Insufficient yellow paint on the pipes.

[numerobis]

In real life (and hopefully in future versions of KSP) rockets with multiple gimbaled engines can point them in opposite directions for roll control. I would imagine the roll authority that would provide would easily counteract the torque from moving fuel around (although steering losses would eat up some of the delta v savings).

I have a plugin to do that. It's not 100% yet (doesn't obey the gimbalRange correctly). You can build it from source if you're brave. Then you change all the "ModuleGimbal" to "ModuleSMRTGimbal" in all your part.cfg files.

[GoDores]

Another factor besides those already mentioned is that rocket programs on Earth don't get their parts from the side of the road, whereas Kerbals do.

In stock KSP we're limited to a few given sizes of engines and fuel tanks. So to launch very large payloads we need to use many separate tanks and engines. If we're already doing that, we might as well add the decouplers and fuel pipes to make the booster asparagus and maximize efficiency.

But an Earth space agency could just design a larger fuel tank and more powerful engine. The F1 engines powering the first stage of the Saturn V are five times more powerful than a Mainsail, and five of them were fed by a single fuel tank. If NASA were forced to use 25 engines and dozens of "orange tanks" for the Saturn V first stage, they might have chosen to use something like asparagus for efficiency. Instead they just built bigger engines and fuel tanks in a single stage.

[RuBisCO]

Staging and drag on not the issue. Many rockets have multiple strap ons. The problem is mainly the fuel pumping from one stag to another.

If I was to make the tech tree harder, I would even put in 3.75 and 5 meter wide tanks before that magic yellow pipe.

[kalor]

Staging and drag on not the issue. Many rockets have multiple strap ons. The problem is mainly the fuel pumping from one stag to another.

If I was to make the tech tree harder, I would even put in 3.75 and 5 meter wide tanks before that magic yellow pipe.

Not that I completely disagree, but even as early as 1947, with Mikhail Tikhonravov, there were forays into cross-feeding parallel stages, and a couple programs, such as Atlas I and II, used a similar system (1.5 stage, or 1 1/2). Despite that, for the most part of (human!) powered rocketry, sequential staging has been the norm.

While multiple bolt-on boosters is the core of an asparagus design, the issue that I have with it in game is the extent that it is taken to. cross-feeding a pair, or possibly even a quad, of bolt-on liquid fueled boosters is (comparitively) simple, and feasible, I have seen designs with 10, 20, or more cross-fed systems, which, in my mind, is not feasible.

If I wanted to leave this possibility open, and yet make fuel crossfeeding something to be seriously considered before just adding a chunk of pipe, I would introduce a "pump" part, required to allow fuel to be pumped out of the tank. Initial pumps would have low fuel-transfer rates at a high electrical cost, and possibly even high mass, whereas more advanced research would improve the efficiency, resulting in higher fuel transfer rate for the same or less electrical cost, same or less mass, etc.

Also, it was stated earlier (not going to go find it ) that in game we have to deal with the hula-dancing long tall rockets for sequential staging, and implied that it isnt a concern for real world rocketry. I have participated in high-power model rocketry, and can tell you that isn't the case. Even at that low (again, relatively...) end of thrust and weight, multi-stage rockets, and indeed, long single stage, have to deal with that. Some of it can be "built out" of the design, via structural support, wall thickening, and so on, but some cannot, and must be compensated for, usually with longer-burning, slightly less powerful motors. Among other ways

[Awaras]

there was one planned russian concept which used an early form of asparagus - the UR-700,which was N-1 rival

My Kod, that is the most Kerbal RL rocket design I have ever seen!

Edited October 23, 2013 by Awaras

[Jarnis]

Yep. UR-700 is definitely very Kerbal. One standardized core being used in large numbers.

[Eric S]

I thought the angular momentum issue was that if you start rolling at all due to exterior forces (which you will), the fuel on the outside gets angular momentum. When it is brought towards the core, the roll gets faster.

Which is also true, but any rocket that can't control a roll has issues to begin with, regardless of what staging it's using. Most people I know that say that angular momentum would kill asparagus staging say it's because the roll is uncontrollable, and that just isn't the case. Yes, if you let a fast roll build up you're going to have a hard time stopping it, worse than in a non-asparagus craft. The point is that you shouldn't let it get out of control in the first place, and nothing about asparagus design would make it that much harder to keep it from rolling to begin with.

While multiple bolt-on boosters is the core of an asparagus design, the issue that I have with it in game is the extent that it is taken to. cross-feeding a pair, or possibly even a quad, of bolt-on liquid fueled boosters is (comparitively) simple, and feasible, I have seen designs with 10, 20, or more cross-fed systems, which, in my mind, is not feasible.

I agree with that, even if I have rarely taken it to such extremes (rarely enough that I can't remember the last time I did). I almost never go beyond six stacks around one, I'd rather go larger than add another layer, and even with the radial decouplers that put distance between the two stacks, eight stacks just get packed in too close to each other for my comfort.

However, I have no clue how to kill multi-layer asparagus without affecting regular aspargus, and I'm not sure I'd want to at any rate, because that would feel like "my play style is ok, but you're taking it too far."

[hobbsyoyo]

My Kod, that is the most Kerbal RL rocket design I have ever seen!

Where did you find information on the UR-700?

[Awaras]

Where did you find information on the UR-700?

Erm... google image search...

[Gus]

Erm... google image search...

Google eh? Let me write that down.

[hobbsyoyo]

I was hoping he had a specific web page with information on the UR-700 as the last time I checked Wikipedia didn't have it. Yes, I could have googled it, but then I couldn't PostCount+1.

[kalor]

However, I have no clue how to kill multi-layer asparagus without affecting regular aspargus, and I'm not sure I'd want to at any rate, because that would feel like "my play style is ok, but you're taking it too far."

Agreed. The only time I think this would become an issue for some is in a (possible?) future multiplayer. But, that being said, I think that with the inclusion of a more realistic drag model, the massive asparagus..es? (asparagii? what is the plural? ) would quickly see a decline.

I think too that more interconnectors that provided more stability, and possibly a "strut decoupler" (acts just like a strut, but decouples as per a normal stage?) would see more sequential staging rockets than parallel, and make more realistic rockets more possible, same with larger diameter fuselage and tank sections.

[Gus]

However, I have no clue how to kill multi-layer asparagus without affecting regular aspargus, and I'm not sure I'd want to at any rate, because that would feel like "my play style is ok, but you're taking it too far."

Does this make sense?

If you want to give a realistic drag penalty to rocket designs with many stacks, make the radial pylon, hardpoint and decouplers' drag values higher. Maybe in the 1 - 3 range. There is always one and only one of these parts used per stack added.

Since the central stack is "free", drag-wise, adding high-drag stacks would steadily decrease the rocket's "drag" efficiency.

If you want to make fuel lines less attractive, make them heavier to account for the weight of the pumps, etc.

[hobbsyoyo]

You have to use more than 1 hardpoint or decoupler in a row in many instances if you want to radially attach 8 large diameter boosters or they won't be spaced properly. This isn't the only way to space them but it is common.

[sickboy]

yeah the UR-700 is basically a kerbal spaceship with better fairings heh.

Hopefully one day we get real fairings and can make rockets that look more like that (without mods)

[LameLefty]

yeah the UR-700 is basically a kerbal spaceship with better fairings heh.

Hopefully one day we get real fairings and can make rockets that look more like that (without mods)

Until we get a much more realistic atmospheric drag model, don't count on seeing fairings in the stock game. In the meantime, KW Rocketry's are great, and Procedural Fairings are even better if all you want are the fairings.

[Eric S]

Does this make sense?

If you want to give a realistic drag penalty to rocket designs with many stacks, make the radial pylon, hardpoint and decouplers' drag values higher. Maybe in the 1 - 3 range. There is always one and only one of these parts used per stack added.

Since the central stack is "free", drag-wise, adding high-drag stacks would steadily decrease the rocket's "drag" efficiency.

It would have the effect you want, but I think it would have some serious drawbacks in other situations because it doesn't matter what you're using the radial decouplers for, a 0.625 m probe or a 6.25m superbooster, it adds the same amount of drag per stack. Which means that even the perfectly normal and acceptable large center stack with two narrow solid boosters gets penalized.

If you want to use aerodynamics to kill asparagus staging (it probably won't, but it could probably kill the multi-layer asparagus abuse), then model aerodynamics to do so, don't hack up something because you don't like it. It reminds me of the old Star Trek roleplaying game, where they actually had rules for dual-wielding weapons that didn't restrict the rules to melee weapons, they just said "Sulu would never consider using two phasers at the same time."

If you want to make fuel lines less attractive, make them heavier to account for the weight of the pumps, etc.

Mass that a 7 stack 3.75m asparagus cluster wouldn't notice would be enough to ground my little Mun lander that only uses fuel lines to suck fuel from radially mounted tanks because without them, it would be too tall to land safely. Having different fuel lines (with differing masses) for different fuel flow amounts is just adding complexity to the game that would affect most designs just to stomp on one class of design, but at least it would have fewer negative consequences other than the complexity itself.

It's really these kinds of unintended consequences that you have to watch out for with ideas of how to limit asparagus staging.

[Moar Boosters]

They could introduce a new fuel pipe for early on in career mode.

One that only allows transfer between two tanks - if you try and connect a fuel pipe from either of them to a third tank, it wouldn't work.

That way you could have onion staging with the outer tanks feeding the inner ones, or drop-tanks like the spaceshuttle..... but wouldn't be able to do more complicated asparagus designs that chain fuel tanks until you've unlocked the more advanced pipe.

[Awaras]

They could introduce a new fuel pipe for early on in career mode.

One that only allows transfer between two tanks - if you try and connect a fuel pipe from either of them to a third tank, it wouldn't work.

That way you could have onion staging with the outer tanks feeding the inner ones, or drop-tanks like the spaceshuttle..... but wouldn't be able to do more complicated asparagus designs that chain fuel tanks until you've unlocked the more advanced pipe.

How about just limiting the amount of fuel per second that can flow through the fuel line? I mean right now a single fuel line can drain an entire orange tank in a second or two if you go overboard with asparagus staging... That's hardly realistic.

[Awaras]

I was hoping he had a specific web page with information on the UR-700 as the last time I checked Wikipedia didn't have it. Yes, I could have googled it, but then I couldn't PostCount+1.

Well, these pages were the most informative ones I could find:

http://www.friends-partners.org/partners/mwade/lvs/ur700.htm

http://www.astronautix.com/lvs/ur700.htm

Edited October 24, 2013 by Awaras