Asparagus-Stalk Booster (Longer Thrust from Efficient Fuel Lines)

[Klopchuck]

Hello! I found a description of something called 'Ed Keith\'s Innovative Asparagus-Stalk Booster' in Tom Logsdon\'s 'Orbital Mechanics: Theory and Applications' (1998). BTW, if you want to learn the maths and rocket sciences, this is a fun textbook.

Anyway, Ed Keith developed a concept that might be familiar to many of your designs:

1) seven cylindrical rockets mated side-by-side

2) all seven engines burning in parallel at lift-off

Please see attached photo of page 144 of the textbook.

However, he also proposed automatically pumping propellant from some of the rockets first, so two of the rockets could be discarded as soon as possible, followed by the next two, and so on, until you are left with the center rocket.

So this may not be new to some of you, but I thought I would take it to the next level with some comparisons of two comparable 21-tank designs:

[list type=decimal]

[li]'Simple' design with an inner-core of 3 fuel tanks and the gimbled liquid engine; the outer six boosters have 3 fuel tanks each, and the LV-T30 liquid engines. Core and boosters are activated immediately upon launch for max thrust; the outer boosters are expended at approximately 187 seconds of full-throttle. The core expends shortly thereafter, at approximately 214 seconds of full-throttle. Average Thrust/Mass is 31.29 for 215 seconds. [/li]

[li]'Asparagus' design with same configuration, except fuel-lines added to pump fuel from boosters 1 and 4 to boosters 2 and 5; from boosters 2 and 5 to boosters 3 and 6, and from 3 and 6 to the inner core. The first two boosters are empty and can be dropped at about 55 seconds, the next stage at about 131 seconds, and the last boosters at about 262 seconds. Then you have the core, with all its fuel, still available for about another 214 seconds of full-throttle. Average Thrust/Mass is 22.99 for 476 seconds.[/li]

What is the proper comparison of spacecraft performance? If I multiply the average thrust/mass times the duration, the Asparagus is 162% of the simple design. All from adding 6 fuel lines and some more-complicated staging! (see attached .pdf for graphs)

Also, I tested the two designs with MechJeb set to ascend to KSO orbit, about 2870km. The 'simple' design without fuel lines and more than two-stages used about 98% of the fuel to get to KSO. By comparison, the 'asparagus' design only used about 84% of the fuel. More than six times as much fuel remaining - much more efficient!

[table]

[tr]

[td]Design[/td][td]Starting Fuel[/td][td]Engines[/td][td]Fuel Remaining in KSO (~2870km)[/td]

[/tr]

[tr]

[td]Simple[/td][td]21 x FL-T500[/td][td](1) LV-T45

(6) LV-T30[/td][td]<0.5 FL-T500[/td]

[/tr]

[tr]

[td]Asparagus[/td][td]21 x FL-T500[/td][td](1) LV-T45

(6) LV-T30[/td][td]~3.4 FL-T500[/td]

[/tr]

[/table]

A .pdf comparison chart of Thrust and Mass is attached, along with screenshots of Keo-synchronous orbit. Please note, MechJeb was used to get the two spacecraft into the same orbit with minimal operator error. A stock-version of Asparagus is attached for your enjoyment.

[Cthulufaic]

It\'s amazing how much spare time people have on their hands nowadays, Not complaining of course.

I like how real-life theories, rockets, and science can affect how good or efficient or fast a rocket is or can be, and

the fact that the drawings in the textbook look surprisingly similar to the 'Instructions' of the first few version\'s loading screens.

[Klopchuck]

Yeah yeah the family is away for Easter weekend - so free time for geeking out on KSP.

Has anyone adapted this to their larger launch vehicles and gotten better performance? Please let me know if this is helpful.

[VincentMcConnell]

Those drawings and diagrams are amazing. Did you make that? If so, how?

[Millst0ne MK II]

Hahahaha! Makes me wanna fire up KSP and make some crazy rockets.

*fires up ksp and makes rocket*

[Klopchuck]

@VincentMcConnell - Charts were created with Excel 2010. I calculated the thrust and mass as functions of time by hand, so it\'s not a very smart spreadsheet. I also assumed instantaneous transitions between stages, which is probably more optimal than possible by hand.

[Optical9090]

Just made a simple type rocket to test this theory for myself.

Chute

Pod

Mechjeb 1m

7 large tanks

7 LV-909

Simple launch, without fuellines, got me to a apogee of 2.150m

Setting 2.150m meters as the baseline i rearranged the staging and attached 6 fuellines then launched.

at 2.150m meters apogee i had a stunning 3/4 tank left in my final stage.

I might try a dubble-layered Asparagus-Stalk booster next.

[sjwt]

Has anyone adapted this to their larger launch vehicles and gotten better performance? Please let me know if this is helpful.

I will have a post for you in the next day or so, I have been working on a SHL version of something like this for two weeks now...

[sal_vager]

I have been using something similar since forever, I didn\'t know it was called asparagus though, I called it daisychaining like with USB hubs.

I tried several different ways to get the stages to run out in sequence, different size stacks of tanks to start with, then running pipes from the stacks directly to the engines but that was hard to arrange, I stumbled on this setup by accident.

This http://kerbalspaceprogram.com/forum/index.php?topic=7764.0 was my test ship at the time and I still like to fly it, it\'s probably not as efficient as an inline rocket because of drag but it\'s fun.

[Seyvern]

See Falcon 9 Heavy (they use this this type of staging)

[Klopchuck]

That\'s cool about SpaceX\'s Falcon 9 Heavy. I hope they actually build and successfully test one! Anyone know why ULA/USAF hasn\'t invested in this improvement to the Delta IV Heavy?

[Kryten]

They have no need for that something that heavy, DIVH is capable of launching the largest things they want to put up.

[Seyvern]

They have no need for that something that heavy, DIVH is capable of launching the largest things they want to put up.

disagree. Plenty of things you might build if you had half the lift capacity of a Saturn V. Currently noone builds them because that lift capacity doesn\'t exist.

[Kryten]

disagree. Plenty of things you might build if you had half the lift capacity of a Saturn V. Currently noone builds them because that lift capacity doesn\'t exist.

Rubbish. They have the DIVH, but only one service, (the NRO) has actually made use of it, the USAF couldn\'t care less. If they don\'t need to use the heavy-lift stuff they\'ve got now, then they certainly don\'t need heavier.

[Seyvern]

I work in this field. Rubish back at you. First, there is the space station. They would build larger more efficient modules if they could. But I don\'t care about the ISS. Here is a real easy example - New Horizon. Ran past limit of the DIVH capability - had to use a unique atlas configuration.

[Kryten]

Yes, but the USAF don\'t want to send probes to bloody Pluto, do they? NASA might, but they\'re funding SpaceX already.

[Seyvern]

You were the one that brought up USAF in the first place. As support for the fact that F9H is a bad idea. Whatever - congratulations, you win this internet argument. F9H is a horrible horrible idea. What could SpaceX be thinking. Back to the originally scheduled thread - Yes, boosters feeding mains is a good idea, and SpaceX is using it (no doubt just to waste their own time and money). It also works great in this game.

Sorry for the threadjacking.

[VincentMcConnell]

As support for the fact that F9H is a bad idea.

Why do all of SpaceX\'s rockets look like dicks?

[sjwt]

I will have a post for you in the next day or so, I have been working on a SHL version of something like this for two weeks now...

As promised, I present my Advanced Super Heavy Lifter, http://kerbalspaceprogram.com/forum/index.php?topic=10468.0

this baby can take 61 FULL Fuel tanks to the Mun! It can take 121 FULL Fuel tanks out to 206,000Kms.

It uses 230 fuel tanks, compare this with my \'Dumb SHL\'(See 3rd image on this page)http://kerbalspaceprogram.com/forum/index.php?topic=9947.msg147832#msg147832 that uses over 270, and that didn\'t get a full load of 24 fuel tanks to the Mun and you can see the advantages to dropping tanks!