Is asparagus the best staging system? (might contain science)

[Pbhead]

Ok. I am really new here, but I wanted to post some !!science!!.

So. I was looking at trying to figure out the best rocket configuration if your payload is fuel.

So, after a whole lot of winging it:

(more at bottom of post), i decided to try study up, and be a bit more scientific.

I learned about asparagus staging, but... something seemed off. so i did some tests.

I created 3 designed, the only difference is the fuel lines and struts(which shouldnt affect things), 3 orange fuel tanks on top of a 32.

Below are the fuel line layouts, the height and speed when the outer stages are dropped, and the craft files if you want them for whatever reason.

https://dl.dropboxusercontent.com/u/36550973/asparigus%20test%203.craft

https://dl.dropboxusercontent.com/u/36550973/asparigus%20test%204.craft

https://dl.dropboxusercontent.com/u/36550973/asparigus%20test%202.craft

As you can see... I kinda messed up. that last image, while i took a frame or two after jettisoning the last stage, as you can see, and you should be able to predict from the fuel line set up, that unlike the other rockets, the fuel will start depleting from the inner stages before the outer stages are completely gone.

so here is a picture of where the rocket is right after jettisoning just the first outer stage... note the quantity of fuel remaining, speed, and height.

So here are the results, nicely tabulated

Standard Asparagus, 2 tanks dropped per stage:

Height Speed Liquid fuel left

18400 216.9 69996

Double Asparagus, 4 tanks dropped per stage:

Height Speed Liquid fuel left

19.7 km 287.1 70308

Serialish outerstage stage, 4 tanks dropped per stage dropped in pretty short succession:

Height Speed Liquid fuel left (after all outer stages dropped)

32.3 km 560.0 59177

Height Speed Liquid fuel left (after first outer stage dropped)

16.7 km 319.8 76869

So basically, I am a little curious on what you much more experienced players think on this. I mean, there are two conflicting forces here, one is the serial stages are keeping more engines on longer thus having a higher thrust for longer, but also means having more empty tanks.

It also makes me wonder about like, ok, what if some of the inner tanks were transfered to the outer stages so that the outer engines burn longer before dropping... Or, have the outer stages have less tanks so that they act like 'boosters' helping the rocket to achieve that first 100 m/s as fast as possible.

these designs have about 400 parts... mostly struts. I have no idea if that is good, bad, or par, but I feel like, why used boosters when mainsails just have a much better power/part ratio... at least before the struts.

So please, I want want your knowledge! or... maybe just see your massively massive rockets!

Like this! which is insanely fun to launch... and gets quite a large quantity of fuel up into space... about 50% of the time.

https://dl.dropboxusercontent.com/u/36550973/Tanker%20mark%206.craft

(does placing RCS thrusters on large arms help with turning? It should... but does it?)

Or this. 1700 part monster which. did not quite work out as intended.

(the middle was, in theory, for a payload.)

[ComradeGoat]

Interesting stuff. Quite often I design asparagus rockets with some stages as drop tanks, to avoid the "dropping engines early" problem. ISTM that the most efficient thing to do is use small fuel tanks and drop them individually as they deplete, and drop engines as they are no-longer needed. This has to be balanced with the increased complexity and decreased structural integrity over fewer, larger boosters, and the layginess of the launch vehicle.

[SoldierHair]

I say long rockets are better than wide rockets.Asparagus doesn't seem good to me.Yes , you have more thrust and more fuel , but you are heavier and have more drag aswell.

[bsalis]

So basically, I am a little curious on what you much more experienced players think on this. I mean, there are two conflicting forces here, one is the serial stages are keeping more engines on longer thus having a higher thrust for longer, but also means having more empty tanks.

One thing to be mindful of when using asparagus-style staging is that if all the stacks are the same, the payload becomes proportionally heavier as you drop stages. So the TWR will go down. That is not what you want at, say, around 10Km where you clear the thickest of the atmo and want to start hammering it east. This can be fixed if you make the stacks smaller (less fuel, same engine, more TWR) as you progress the staging sequence.

Or... just don't use asparagus-style staging. I do not. Sure it's more efficient, but more complicated and harder to build robust large craft.

[Plur303]

I say long rockets are better than wide rockets.Asparagus doesn't seem good to me.Yes , you have more thrust and more fuel , but you are heavier and have more drag aswell.

The way aerodynamics are currently implemented the area of your rocket does not matter. Nose cones also slow you down and do no good. They are just dead weight. The developers have said they are going to update the aerodynamics some day but it is not happening any time soon. For the time being there is no aerodynamic penalty for having a wide rocket with flat tops on the tanks.

Here is a detailed test I did of the same rocket using different staging methods. Sorry if the size is too big. I wanted to fit everything in 1 frame so I could post this on other forums and discussions about the game, not just here.

I used mechjeb to remove human error. It flies the exact same ascent program for all the flights. As you can see, asparagus staging greatly increases the performance of the exact same rocket.

Link to full size. Small text is visible in full size http://i.imgur.com/XDlDujR.jpg

One thing to be mindful of when using asparagus-style staging is that if all the stacks are the same, the payload becomes proportionally heavier as you drop stages. So the TWR will go down. That is not what you want at, say, around 10Km where you clear the thickest of the atmo and want to start hammering it east. This can be fixed if you make the stacks smaller (less fuel, same engine, more TWR) as you progress the staging sequence.

Or... just don't use asparagus-style staging. I do not. Sure it's more efficient, but more complicated and harder to build robust large craft.

This is very true. The exact same generic asparagus lifter might not be better in all situations. However, I still believe that with a little tweaking and playing around with thrust to weight ratios of the different stages asparagus is always going to be superior.

I highly recommend the Kerbal Engineer mod for everybody.

http://kerbalspaceprogram.com/0-18-1-kerbal-engineer-redux-v0-5/

It shows you the thrust to weight ratios of every stage and also shows their thrust to weight ratios on other planets/moons. This helps you design landers for other places and saves you from carrying too much fuel to a place like minmus. If you make your lander smaller and more efficient then you can also make your boosters smaller.

Using Kerbal engineer you can tell if your 3rd asparagus stage is going to be too weak.

So to sum it all up. There is no generic "asparagus" design that is automatically better. What it really comes down to is the thrust to weight ratio of each individual stage. If you manage the thrust to weight ratio and keep it around 2 to 3 for launch stages then you will be fine. You don't want to go too fast at low altitudes so anything above about 2.5 is getting wasteful for low altitudes because of air resistance. You will need to throttle back.

Edited May 9, 2013 by Plur303

[oggylt]

Kerbal, that craft 206 looks like a beast INsane

[Temstar]

Assuming we're talking about taking off from surface or Kerbin to reach orbit, and without resorting to jet engines - yes, asparagus staging booster is ALWAYS the best staging system.

One thing to be mindful of when using asparagus-style staging is that if all the stacks are the same, the payload becomes proportionally heavier as you drop stages. So the TWR will go down. That is not what you want at, say, around 10Km where you clear the thickest of the atmo and want to start hammering it east. This can be fixed if you make the stacks smaller (less fuel, same engine, more TWR) as you progress the staging sequence.

See this is the issue here. If all the stacks (most importantly the centre core stack) are the same size then the TWR will progressively go down and this is a potential problem area that messes up people's asparagus staging rocket. The solution then is simple: have a centre stack that's more powerful than the boosters.

Let's look at the TWR for this craft:

For a payload of over 110 tons a 593 ton rocket underneath manages to deliver it to a 75km x 75km LKO with an relative consistent TWR for all stages, how do I manage this? With a very powerful core stage:

Here we see the powerful double cluster of the core stage. It's powered by eight LV-T30 and four LV-T45 for a total of 2520kN of thrust, compared to the 1500kN of each of the rocket's mainsail boosters.

Basically when it comes to working out TWR for an asparagus, we have to balance a number of factors. Let's see how we go about designing a well balanced and efficient asparagus staging rocket to illustrate what I'm talking about.

1. First is payload fraction. An exceptionally well engineered asparagus staging rocket can manage over 16% payload fraction, far higher than any other type of staging and thus making it unquestionably the most efficient type of staging. When efficiency is the goal you should aim for at least a payload fraction of 15%. And so given a known payload - say 44 tons. You already know how big that rocket is:

44 * 100/15 = 293 tons

So for a payload of 44 tons, you should be able to lift that into orbit with a rocket weighing 249 tons for a total stack of 293 tons.

2. Second, now that we know how big of a rocket we are designing we can figure out how to engine this rocket. The number that's important here is TWR at lift off. Given that the ideal ascent profile calls for a TWR of 2 before Max Q, you want lift off TWR to be below 2 so that by the time of first staging event your rocket's TWR goes above 2 and the two ends balance each other out. I find that the ideal TWR at lift off for an asparagus is between 1.6 - 1.7. The Nova rocket above as we can see have a lift off TWR of 1.67

So, given 293 tons:

293 * 1.6 * 9.81 = 4599 kN

293 * 1.7 * 9.81 = 4886 kN

Thus, we know that our rocket that can lift 44 tons need to have enough engines at the bottom for a lift off thrust of 4599kN - 4886kN

3. Last, we need to figure out exactly how we can engine this rocket to give us 4599kN - 4886kN and using an asparagus design. As we discussed above for a more consistent thrust we need the centre stage to be more powerful than the boosters. But exactly what ratio of core stage thrust vs total thrust should we use? There is no clear answer here but my own experience tells me the ideal ratio is somewhere around 22%. That is 22% of the rocket's thrust should come from its final stage while 78% comes from the asparagus staged boosters around it.

So given our 4599kN - 4886kN thrust what engines should that be? well 22% of that thrust is 1012kN - 1075kN. This number clearly shows us what engine we should use:

4 x LV-T30 = 860kN

1 x LV-T45 = 200kN

For a total of 1060kN which falls in our range. Thus we know for our 44 ton payload rocket, we should use a core stage powered by a five engine cluster of four LV-T30 and a centre LV-T45, which also gives us a good steering authority via vectored thrust.

So now that we know our core stage, that leaves 3539kN - 3826kN of thrust that must come from the asparagus boosters around it. Exactly how many boosters is up to personal choice - the more you have the smoother your TWR curve and the closer you approach the "ideal staging rocket" that never carries any dead weight in terms of empty tanks or excess engine. On the other hand the more boosters you have the more complex the rocket becomes to engineer. I find that the ideal number for 2.5m core stage with 2.5m boosters is six. Six is the maximum number of 2.5m boosters you can cluster around a 2.5m core using standard long decouples, if you want more you have to resort to much more complex engineering for diminishing return which I find is not worth it.

So say we settle on 6 boosters around our 1060kN core. This gives us 590kn - 638kN per booster. Again the choice is clear:

2 x LV-T30 = 430kN

1 x LV-T45 = 200kN

For a total of 630kN per booster. Thus we now know the engine configuration of our 44ton payload rocket:

• a core stage of 4 LV-T30 and 1 LV-T45 for a 1060kN
  
• six boosters of 2 LV-T30 and 1 LV-T45 to give 630kN per booster
  

The total thrust at lift off is thus 4840kN. These engines weigh a total of 30.5 tons. Our payload is 44 tons, so according to the 293 ton number we worked out in section 2 this leaves us with 218.5 tons for mostly fuel + other hardware for the rocket. Your job then as a designer is then simply work out how to distribute that 218.5 tons of mostly fuel so that each stage has reasonable TWR. The end result will look something like this:

As it turned out asparagus staging is so good we didn't actually need 218.5 tons of fuel to lift 44 tons of payload into orbit. The final rocket turns out to be 234 tons including the engines for a payload fraction of 15.89%. Better than the 15% target we were aiming for and far better than what's possible with other types of staging.

The above process is what I followed when I designed the Zenith rocket family:

Edited May 9, 2013 by Temstar

[Chruschtschow]

Hm, seems like I should rethink my approach to launcher building. MOAH MAINSAILS!!! is fun, but not necessarily efficient.

[Paul Kingtiger]

When I first started playing I wondered why Asparagus wasn't used in real life. I assumed at the time it was due to the complexity of having so many stages and pumping fuel around stages, both these thing could lower reliability to the point where it wasn't worth it in a system where things can and do go wrong.

Now I'm more experienced in the game and have read quite a few books on rocket science and orbital mechanics I think the reason is as follows:

In KSP each part has a drag value, and causes drag regardless of how it is placed in the stack, in fact currently, aerodynamic nose cones actually add to drag not remove it. In real life aerodynamics fat rockets generate a lot more drag and tall thin ones so the benefits of Asparagus is lost with the extra drag (past a point).

A more realistic aerodynamic model is on the Devs to-do list so we may see Asparagus become less useful then.

[Temstar]

It's not the drag, is the TWR of the engines and the dry weight of the tanks.

In the real world:

• engines have TWR approaching 100 (94 for F-1, 137 for NK-33, 160 for Merlin 1D)
  
• dense fuel tanks can have a dry weight as little as 1% of the fully fuelled tank
  

In KSP:

• highest TWR liquid fuelled engine is mainsail with a TWR of 25.5
  
• bipropellant tanks have a dry weight ratio of 11%
  

In KSP both engines are fuel tanks are so inefficient that for the same level of thrust you need engines 4 times as heavy in KSP. And for the same amount of fuel you need fuel tanks more than 10 times as heavy. With tanks and engines so heavy the advantages of getting rid of them as early as possible becomes huge. Where as in the real world a much higher proportion of the rocket's weight are fuel. With the rocket hardware being only a tiny fraction of the fully fuelled rocket's weight there is much less incentive to ditching parts early.

[Nuke]

i usually end up doing a 2 stage with a massive lower stage (14 orange tanks and 6 mainsails on the outer ring) with mainsails doing everything. then have an efficient upper stage using engines with isp 380 or better (sometimes nuclear engines, or the mpd engines from my mod). its not the most efficient approach by a long shot, and it either falls way short and burns up, or ends up with the whole first stage in orbit with some fuel onboard.

[iRommel]

i used staged asparagus.

basically its an asparagus rocket ON TOP of asparagus stages.

so i have 7 mainsails at the bottom... 2 tanks drop off and expose 2 more mainsails at the middle of the rocket which then fire. the key is terminal velocity and TWR. i use mechjeb and i can see that this configuration keeps my rocket just under terminal velocity nearly the whole time minimizing loss due to gravity and drag because it moves quickly to get out of the air.

my previous long asparagus rockets would drop off a stage and then would be rather heavy with 2 less engines. if i configured the rocket differently to have 9 mainsails firing at the beginning it would hit the terminal velocity and beyond.

[Eric S]

In KSP both engines are fuel tanks are so inefficient that for the same level of thrust you need engines 4 times as heavy in KSP. And for the same amount of fuel you need fuel tanks more than 10 times as heavy. With tanks and engines so heavy the advantages of getting rid of them as early as possible becomes huge. Where as in the real world a much higher proportion of the rocket's weight are fuel. With the rocket hardware being only a tiny fraction of the fully fuelled rocket's weight there is much less incentive to ditching parts early.

I hadn't thought about that, and yes, that's probably a major factor.

Other factors:

Fuel lines: They're just not as easy in reality as in KSP. I think the US Space Shuttle (and probably the Buran) was the first craft to do a fuel transfer during launch, and the Falcon 9 Heavy which hasn't been tested yet is the only other craft that I'm aware of that does it. Did Burran

Aerodynamic drag: Nope, not talking about delta-V used to counteract drag, that's a very minor factor at most. If you've launched rockets using FAR which has more accurate aerodynamics than stock, you know that rockets with a center of drag higher than their center of mass are inherently unstable. This isn't necessarily the case with all asparagus staged vehicles, but I ran into it more than once while testing. Also, since real earth launch gravity turns tend to more closely follow the prograde, this is less of a factor in reality since the instability is easily correctable if you're close to prograde, it just becomes bad if you turn as far from prograde as you do following the informal standard of "turn to 45 degrees at 10K altitude.

I've heard someone on these forums mention the rotational energy of transferring the fuel would cause a problem. I don't think so, for your normal three stages plus center stack, I'm pretty sure you'd get 70 degrees of rotation at most, and that's assuming a massless center stack.

Excess mass?: Nope, from what I've seen, asparagus staging has a higher payload percentage than single stack rockets, so by definition, an asparagus staged rocket that could put X tons into orbit would have less mass than a non-asparagus one. If you're seeing different results, you may be overbuilding your asparagus rockets.

More parts: This is also true. Having a fuel pump go out in the innermost asparagus stage could mean that none of the stacks on that leg would transfer fuel correctly, throwing the entire ship out of balance. While it only has this effect in game if you incorrectly attach the fuel line, more parts can still be bad for performance depending on the total parts on the craft.

[rkman]

I say long rockets are better than wide rockets.Asparagus doesn't seem good to me.Yes , you have more thrust and more fuel , but you are heavier and have more drag aswell.

For a given destination asparagus gets you there with less fuel and less mass than a conventional rocket.

Increased drag of asparagus is as of yet not an issue in KSP.

Asparagus is more efficient wrt to the ratio of useless mass to usefull mass of a rocket, and therefor is in princial more fuel efficient. In reality it is rarely used because of more complicated and therefor more costly engineering.

[Pbhead]

Thank you for all the great replies! Especially Temstar and plur.

And yes, oggylt, it is a beast. It is timed out so that the solid rockets and liquid rockets run out of fuel at approximately the same time... which is pretty cool, because it means every time you drop a stage you get a new fwooosh from new engines lighting up... something you dont really get with asparagus staging (no fwoosh is biggest problem with asparagus)

I would imagine the "best" rocket, would be a rocket that uses a serial stage to get really quickly to 100 m/s (sepratrons?!?), drops serial stage, then slowly asparagus lumbers to 260/10,000, each stage having slightly less fuel to maintain TWR, then when the last one drops, the rocket once again shoots off on another high engine/fuel ratio stage.

I also imagine some sort of chariot (or podracer)-like rocket... Engines up high, and radial to a central fuel tank column which can then drop each tank the second they empty.

I think i am going to try that info mod, and try some new rockets!

Edited May 9, 2013 by Pbhead

[numerobis]

My design plan tends to be that I build the payload, then attach an asparagus pair with some fuel. Check the TWR, and modify the fuel quantity until I have the TWR I need (a bit shy of 2). Repeat until I have enough deltaV. Typically my payload has an LV-N or an LV-909 that I use all the way up; that or a pair of 24-77s that I toggle on at the beginning of every stage to boost my thrust a tiny bit when TWR is low, then off when TWR is back up.

Low stages may benefit from drop tanks: just add some asparagus spears without engines, instead of stacking tanks on top of an engine. Higher stages generally don't benefit: you have to remember to account for the mass of the decoupler. So you end up calculating that yes you save from having dumped say 500 kg you'd otherwise have hauled up an extra 250 m/s, but you had to haul 50kg of decouplers for 3km/s, so it was a net loss (it's tedious to check all the possibilities of course).

For smaller rockets, it can work to have one column of tanks down the middle and attach the engines outboard on cube struts. That lets you halve the decoupler mass: you only need one decoupler to dump a stage, rather than two. In turn that means you can do more drop tanks. This design doesn't resemble an asparagus at all, but it's the same concept of having all engines fire all the time so you never have dead engine mass. The major disadvantage is just that you can't use the LV-N on your payload like this.

[Anglave]

I would imagine the "best" rocket, would be a rocket that uses a serial stage to get really quickly to 100 m/s (sepratrons?!?), drops serial stage, then slowly asparagus lumbers to 260/10,000, each stage having slightly less fuel to maintain TWR, then when the last one drops, the rocket once again shoots off on another high engine/fuel ratio stage.

The ideal rocket sheds dead weight immediately. We can approach this by using smaller tanks and ditching them ASAP.

There's also a trade off between getting away from Kerbin's gravity quickly vs. losing thrust to drag in the dense atmosphere. You've laid out a good plan there, getting up to 100 m/s quickly, then accelerating such that it's passing 200 m/s as it's passing 10km altitude. Ideally, it should do this at full throttle, because otherwise you're paying (in mass) for engine potential you're not using.

Paired Asparagus should always be more efficient (if correctly designed) than onion or other staging (or no staging) strategies. You just have to work out your TWR and make sure you're not carrying more mass up than you need to be. One good rule of thumb is to never lift engines that aren't pushing (except possibly as part of your payload.) If you found quads-asparagus to be more effective, it's likely that your paired design is losing efficiency to atmospheric drag (too fast too low) or gravity drag (too low for too long), indicating the TWR needs attention.

The "don't lift engines that aren't pushing" rule also applies to boosters. I see in your screenshots that you're carrying up solid boosters that don't fire until later stages. Though they're powerful, their efficiency is poor. Generally you want your ISP to increase as your rocket stages. Carrying high thrust/low efficiency engines farther from Kerbin just makes the whole craft even less efficient.

Unfortunately, both in the game and in real life, Asparagus is more complex, requires more parts, and may be more prone to failure than simpler staging strategies. Some simple lifts may be more practically and reliably achieved with a simpler craft.

I spent a long time trying to build huge lifters, in an attempt (in 0.17.1 before docking) to lift an interplanetary Laythe and return mission in one huge launch. The most important thing I learned wasn't about how to design a lifter. It was to make the top stages smaller and more efficient. This cascades (exponentially) down your rocket. If you can get the mission done with a 40t craft instead of a 60t craft, your Kerbin launch vehicle ends up dramatically smaller and simpler.

I also imagine some sort of chariot (or podracer)-like rocket... Engines up high, and radial to a central fuel tank column which can then drop each tank the second they empty.

I built a stack like this in 0.17 but it was unstable because the game didn't account for the vectored thrust being ahead of the center of mass (so the vectoring was reversed). Has this been corrected in the current version?

Edited May 9, 2013 by Anglave

[Eric S]

I would imagine the "best" rocket, would be a rocket that uses a serial stage to get really quickly to 100 m/s (sepratrons?!?), drops serial stage, then slowly asparagus lumbers to 260/10,000, each stage having slightly less fuel to maintain TWR, then when the last one drops, the rocket once again shoots off on another high engine/fuel ratio stage.

If you do that, you still have dead weight on your rocket. I've been known to put a bigger engine or SRBs on my outermost asparagus stage, but I've never noticed it making a distinct improvement on your total delta-V to orbit assuming that your early stages are around a 2.2 TWR. I'm not sure hitting 100 m/s in three seconds is that much better than doing it in 10-15 seconds.

I also imagine some sort of chariot (or podracer)-like rocket... Engines up high, and radial to a central fuel tank column which can then drop each tank the second they empty.

I've thought of that and even use it occasionally, but not as a launch concept. My atomic powered Duna lander sometimes takes an extra fuel tank mounted under the rover, which it of course has to ditch before it lands, just to make sure I have plenty of delta-V left over for stupidity on my part. I generally find that it doesn't gain much over traditional asparagus staging because you either keep the engines, trading delta-V for a high TWR ratio that doesn't necessarily help your efficiency, or you're dropping them about as fast as you would a properly balanced traditional asparagus staged rocket. Oh, and leaving tanks on the launch pad can be a serious problem with this design concept.

I built a stack like this in 0.17 but it was unstable because the game didn't account for the vectored thrust being ahead of the center of mass (so the vectoring was reversed). Has this been corrected in the current version?

No, but you can turn off vectoring on the engines so that at least they're not fighting against you.

And I agree with the rest of your points as well. Back when I had KW rocketry and Nova Punch installed, I often didn't use the same engine in two consecutive asparagus stages just trying to keep my TWR in the optimal range.

Edited May 9, 2013 by Eric S

[RoboRay]

When I first started playing I wondered why Asparagus wasn't used in real life. I assumed at the time it was due to the complexity of having so many stages and pumping fuel around stages, both these thing could lower reliability to the point where it wasn't worth it in a system where things can and do go wrong.

Now I'm more experienced in the game and have read quite a few books on rocket science and orbital mechanics I think the reason is as follows:

In KSP each part has a drag value, and causes drag regardless of how it is placed in the stack, in fact currently, aerodynamic nose cones actually add to drag not remove it. In real life aerodynamics fat rockets generate a lot more drag and tall thin ones so the benefits of Asparagus is lost with the extra drag (past a point).

It's not used in real-life because conservation of angular momentum would result in an ever-increasing, unstoppable roll of the craft as the fuel spiraled inward to feed the core stage.

And moving that much fuel from tank to tank to tank while feeding engines consuming vast quantities of it is pretty much an impossible engineering challenge.

Not to mention that disconnecting fuel lines while engines are burning is a rather dangerous activity.

The drag induced by an asparagus setup isn't any greater in real-life than any other lateral booster arrangement, and those are used extensively.

[rhoark]

I've stopped asparagusing due to the hassle of preparing the staging (and the unrealism doesn't endear it to me, either.) Part of the efficiency is having lots of TWR at the pad but shedding engine weight and surplus thrust quickly (well before max Q), which can be replicated with SRBs, a short serial first stage, throttle control, or jettisoning some engines in an action group.

[ComradeGoat]

The drag induced by an asparagus setup isn't any greater in real-life than any other lateral booster arrangement, and those are used extensively.

That makes sense to me. People talk about how a decent drag model would kill asparagus, but I'm far from convinced. We're only that concerned with drag for the first 8-10,000 metres anyway, and to a first approximation an asparagus rocket is just a load of individual rockets flying in formation.

[lobsterbark]

I say long rockets are better than wide rockets.Asparagus doesn't seem good to me.Yes , you have more thrust and more fuel , but you are heavier and have more drag aswell.

You clearly don't understand how drag works in ksp. Both designs have the same amount of drag, but serial staging requires better engines, which is extremely limiting if you don't have a bunch of op mods. Asparagus is 1000% as efficient, in most tests.

[Pbhead]

The "don't lift engines that aren't pushing" rule also applies to boosters. I see in your screenshots that you're carrying up solid boosters that don't fire until later stages. Though they're powerful, their efficiency is poor. Generally you want your ISP to increase as your rocket stages. Carrying high thrust/low efficiency engines farther from Kerbin just makes the whole craft even less efficient.

Ya, I realized that at the time, but basicly the thinking was this: If i figure out how many solid rocket boosters a solid rocket booster can lift, then while at launch that first solid rocket booster does nothing but neutralize the 'weight' of the other solid rocket boosters... but now i have solid rocket boosters higher up, which will contribute to canceling out the effect of dropping mainsails with the asparagus.

I have also messed with jet engines, which are fabulous, but the TLR (thrust to lag ratio) is really high.

The nice thing about the solid rocket boosters, is that while they only give 315 thrust, they usually only take 2 parts (itself + radial decoulper, less if you have timed your liquid fuel to expire right when the solid does, and you can drop them together)... while a liquid fuel 'booster' takes the engine, the fuel tank, a decoupler, and a whole lot of struts cause that thing is powerful.

It's not used in real-life because conservation of angular momentum would result in an ever-increasing, unstoppable roll of the craft as the fuel spiraled inward to feed the core stage.

That is really easy to fix... sort of. Drop your engines in a 4-2-1 configuration, instead of 2-2-2-1. If that makes sense.

[Alfastar]

You clearly don't understand how drag works in ksp. Both designs have the same amount of drag, but serial staging requires better engines, which is extremely limiting if you don't have a bunch of op mods. Asparagus is 1000% as efficient, in most tests.

Well, in KSP, asparagus staging works good, at least, it depends about the rocket. However, when we talk about real, earth drag, then it become a total other story.

So, asparagus staging can help a lot in some cases, but in some other cases, it don't really helping anything.

[RoboRay]

That is really easy to fix... sort of. Drop your engines in a 4-2-1 configuration, instead of 2-2-2-1. If that makes sense.

There are other momentum effects that impact it. And the other factors I mentioned.

If it was "really easy to fix" I'm pretty sure NASA would be doing it.