Is "Hugging Terminal Velocity" more costly than "Following Terminal Velocity"

[Fel]

People seem to want to design rockets in this fashion.

Stage 1)

TWR "Super Like High"

Gets to terminal velocity asap.

Stage 2)

TWR "Still Super High"

Engines are capable of putting out more than they currently are

Stage 3)

TWR "LIKE REALLY HIGH!!!"

Engines are putting out a pittance of their capabilities.

Stage 4)

TWR "WHAT THE HECK"

Engines now are actually pouring out full power because terminal velocity is "non-issue"

"Stage 1" can easily be dismissed as a srb stage, but "Stage 2" is rather silly... you're carrying a "heavy engine" without using the thrust it can produce... and as you go up, you're rapidly dropping the throttle because your TWR is so unbalanced that the fuel you burned has caused you to go way past terminal velocity hence "Stage 3"...

But then, after carrying those engines for so long, you reach stage 4 where you finally actually make use of them.

What gives? "Stage 2" -> "Stage 3" where you're lowering throttle like crazy is such poor design because you can simply "follow" terminal velocity, stay close, but don't "hug", hence you won't have enough power to overshoot until "Stage 4". The "Delta V difference" is biased because the other rocket has a greater mass.

"Stage 4" is where you have a massive TWR, but less fuel (TWR comes at the expense of load, hence fuel), Why? You cannot "escape" gravity... so why not "use" gravity to your advantage? Unless you're considering the pitiful edge of Kerbin's atmosphere to be robbing you of too much delta V (Again, bigger engines = more mass = more fuel = why are we even talking about this?)

[UmbralRaptor]

People tend to overengine (or underfuel) rockets. For rockets with lots of stages, I'm with Foamyesque -- the VAB should be your throttle, and you should be dropping engines as you burn fuel. TWR is a lot less important once you're mostly pitched over anyway, as gravity drag stops hurting so much...

[Eric S]

I'll second the VAB being your throttle. My rockets tend to be at or near full throttle as much as possible. Asparagus staging actually makes that a bit easier if you're not using identical engines, since you're hitting staging events faster, so you're not burning as much fuel before you stage.

[alex the killa]

I've started changing the designs of my ships so I can go full throttle the entire time. In Asparagus staging, that means adding fuel tanks to the 1st and 2nd stages dropped (generally), and sometimes the 3rd. Works beautifully

I used it to get 750t to space too =D

[Procyon]

how often do you see anyone just dropping empty tanks that have no engine? mainsail can push almost 3 orange tanks so I set up tanks asparagus style and drop em when empty. woks ok for me

[XeroCoolUSN]

Do engines become less efficient as their temperature rises? If they do I would say going full firewall isn't a good idea.

-X

[UmbralRaptor]

Do engines become less efficient as their temperature rises? If they do I would say going full firewall isn't a good idea.

The only thing affecting stock rocket engine efficiency is ambient pressure. Throttle, heat, speed, etc don't factor in.

[Sir Nahme]

it is more efficient to hug terminal velocity as best you can, even once it starts spiraling far faster than you can go, you want the minimum burn time possible

[Atanar]

If I am not lifting a super heavy thing I am using skippers and LV-Ns as soon as I can. I agree with the op, if you want to use less than a third of your throttle you build your rocket wrong.

[UmbralRaptor]

For mainsails, I would argue that you want to stay at or above 2/3 throttle. If the craft needs to go below that, consider a redesign. (Obvious exception: SSTO)

[numerobis]

Nice graphic!

The mainsail also has worse Isp than the alternatives, so you can only tolerate even higher throttle when using it before being better off with a lighter engine.

Who are the "people" mentioned in the OP? You'd get a [[vague]] tag on Wikipedia for such a claim.

[AmpsterMan]

I don't know if this could be an excuse or not, but I have very recently done away with the Asparagus staging and started using serial staging more often.

The result is that I usually have a very large first stage that nets me anywhere from 3-3.5 km /s of dv and a second very small stage that dies the rest. This usually has the side effect of having to slow my thrust down but I enjoy ig a lot more.

[Fel]

Even staying at 2/3 power for anything but the last few seconds of the burn can be a fair bit wasteful, especially when you have more than 1 engine (unless you're combating structural / engine diversity issues). If you don't have an SRB stage or otherwise, you'll end up with a higher TWR than you can use for most of the ascent.

@AmpsterMan, remember that you don't even NEED a TWR of 1 once you get passed the first 10,000m. INFACT, it can actually be better to go over terminal velocity over for those last few thousand meters because it raises your apoapsis, hence giving you a boost while initiating the gravity turn.

@numerobis, Why one of them is in this very thread, giving an overly general statement that can only be achieved by holding onto big fat engines that will only drag you down hence creating a bigger rocket... I've heard this statement been given many times, and I've seen it on the spoiler ridden wiki... "Wikipedia" nonsense aside, I should not need to list offenders to bring this point out.