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[BigD145]

Now it's all testers with advance unstable pre-.22 official release versions.

[Leonon]

Now it's all testers with advance unstable pre-.22 official release versions.

The build just wants the rockets to not feel so bad about their own instability.

KSP test builds, crash the game while you crash your rockets.

[ank]

Subassembly looks awesome!

Shock-absorbing legs will make my Roller able to crash land at 60m/s!

[ahappydude]

http://forum.kerbalspaceprogram.com/threads/39650-0-21-Shock-absorbing-landing-legs-V1-2-%2805-09-2013%29

[10ebbor10]

Yes, we know some dude thought of it first. All major features were probably added before the devs got to it, but in most cases the dev version was better.

What's your point actually? That the devs should stop developing any feature that any modder has made an attempt at doing? That they should remove modding options so that they can keep ahead of modders?

[Eclectic Wizard]

I hope its not going to be like with minecraft where they just implement half arsed versions of whatever mod caught their eye, like the horses, wheres my alligators and lions and stuff?

Really.

Also someone should steal KAS and update it for .22

[forsaken1111]

I hope its not going to be like with minecraft where they just implement half arsed versions of whatever mod caught their eye, like the horses, wheres my alligators and lions and stuff?

Really.

Also someone should steal KAS and update it for .22

The KAS dev said his top priority is preparing for .22 so it shouldn't take too long

[ank]

So I've been thinking about how asparagus might sometimes not be the most efficient, that sometimes not adding engines to the drop tanks will save weight.

My experiment involved a craft with 2 drop tanks. With engines it went to 837km height, but without the extra engines it went to 1.100km height.

Some of this may be due to increased drag from overthrusting, but it does save a lot of weight not having extra engines.

[ahappydude]

Yeah kas is in good hands, i think one of the devs for kethane are going to take over later on so kas will stay Hahaha   Eclectic Wizard i  agree (Y)   .

[forsaken1111]

So I've been thinking about how asparagus might sometimes not be the most efficient, that sometimes not adding engines to the drop tanks will save weight.

My experiment involved a craft with 2 drop tanks. With engines it went to 837km height, but without the extra engines it went to 1.100km height.

Some of this may be due to increased drag from overthrusting, but it does save a lot of weight not having extra engines.

Any time you are thrusting greater than terminal velocity you are wasting energy. Try it again but limit your speed to 200ish m/s until you get above like 30-40km. Or use mechjeb to do real repeatable testing and remove human error. It can limit thrust to terminal velocity for you.

[Sean Mirrsen]

What I am currently wondering is, how different is asparagus staging to rocket-propelled drop tanks?

I.e, in a simple setup like I use, where there are only 2 boosters asparagus linked to the center stack, the proportion of fuel that the center stack draws from the boosters' reserves, assuming they are all fired simultaneously, is quite constant.

Will it matter significantly if the boosters simply contain an extra tank for the center stack, separated from the boosters' own? I'm thinking real-life applications here mostly, because it doesn't really matter in KSP, and introducing decouplers to separate the tanks would degrade performance. In real life though, the separate-tank approach is mechanically and logistically simpler.

[10ebbor10]

It will barely have an effect, as the amount of fuel used is easily predicted. Besides, most fuel tanks are dumped before they're completely empty, because of inconsistent burns between the individual boosters, and propellant pressure loss.

Though well, the main problem with these type of designs is a possible fuel leak, because the tubes aren't as strong as they're in KSP.

[Sean Mirrsen]

The Shuttle has a drop tank, which seems to have worked well.

The only different thing is segmenting the tank into two calculated halves and putting a rocket engine on the underside to make use of one. A "rocket propelled drop tank", as I've come to call the thing that powered my Celestia's Guidance mothership series.

Essentially, the booster both gives the rocket its lifting power, and carries enough fuel for the main engine to last for the duration of the booster's burn. It's a concept that requires much less complexity than real fuel crossfeed, even though it requires boosters custom-made for every given lifter.

[10ebbor10]

The shuttle's drop tank was expensive, unbalanced the craft and led to the destruction of spaceshuttle Columbia*. It might have been the isolation material, but that reveals another interesting point why droptanks aren't used often.

Solid fuel is preferred for side boosters, because while it has lower thrust/weight, it is much more stable and easier to handle. Liquid fuel needs to be filled, cooled, pressurized and stabilized, hugely complicating a launch*. This is the primary reason that the proposed Ariane 6 would have an all solid fuel bottom stage, and a small liquid fuel orbital stage.

Taking a meaningful amount of fuel with you in that tank requires delaying the tank separation, making recovery of the boosters harder, thereby increasing costs.

So while splitting up the tanks might be a good idea, the Aspergus itself might not be.

*Double that if you make your sideboosters of 2 separate tanks.

[Girlinhat]

When is it good to have asparagus staging with rockets:
When your vessel is so heavy that thrusting through the dense lower atmosphere and tighter gravity is more difficult, and you need a lot of raw power to simply push through the air and then drop the extra engines when you get to upper atmosphere, because the air is thinner and you can make do with smaller thrust.

When is it good to have simple drop tanks without rockets:
When your vessel is light enough that a single engine has a >1.0 TWR, and can be lifted effectively with the smaller thrust, in which case it will only get a higher TWR as it continues to burn and shed empty tanks.