So What Exactly Is Delta-V?

[GoSlash27]

I'm not sure that that helps a beginner any more than anything else that's been suggested.

Sure it does. A beginner just wants to know what the term means and how it's used. They will no doubt have more questions later on down the road, and they tend to ask when confused about something.

We egghead types have a habit of going all "precision police" to make sure that we are conveying our information with no misunderstandings, and this is one of those times that the tendency must be avoided. It doesn't help anyone to get so bogged down in the technical discussion that the gist of it gets muddied, confused, or lost.

Best,

-Slashy

[Pecan]

...I'm a firm believer in using only what the game devs have provided, (Also hoping that flying old-school will make me a better pilot in the long run,) so I haven't installed MJ or any other mod that provides calculations or other such readouts of Delta-V. Basically the stock game has no way of calculating it whatsoever, so up until now it's been a 'Non-existent" part of my gameplay. If you know what I mean.

...

Everything so far has been extremely trial and error and without a system of calculating what kind of Delta-V I need to have in order to...land that rover on Eve, for example, before I actually get there and experience it, I feel like the only option is to go there and fail a dozen times until I figure out exactly what I need to build. It's a very time consuming process, which, in the end, has always led to me burning myself out...

Nothing to add on what deltaV is. Plenty on why you should use KER/MJ/VOID or at least a spreadsheet to calculate it.

Rephrase your other question as "Will knowing nothing about my car's endurance make me a better driver?" and the answer is ... it won't make any difference at all to your driving but might make all the difference in the world (pun) to where you drive. Assume it's got a full tank, without refuelling would you drive a) to the nearest shops?, across the continent (whichever one you're on)?, c) somewhere in-between that you haven't been to before?

In other words you NEED to know the ship's deltaV if you want to know where it can go (without refuelling).

It is also not true that "the stock game has no way of calculating it whatsoever", it just doesn't do that calculation for you, despite more than 80% of us asking for just that in a forum poll a few months ago. All the information you need is provided by the game so if you refuse to use a mod use a spreadsheet. Of course, you'll have to retype all the parts' stats every time KSP changes and you'll have to recalculate everything every time you make any change to the ship's mass, fuel and/or engines, but that's the cost of being 'pure'. Real rocket scientists use computers, you know, and used sliderules before that; it's not cheating to work out the figures you need!

Which brings us to your final point, about design and construction rather than flight. The answer here is even simpler: if you aren't calculating dV and TWR for each stage of your ship you just aren't engineering, you're hoping.

The information mods are there because they make vital information a lot easier to get than doing it by hand/spreadsheet. We nearly all wish the figures were available in stock but Squad think "the only option is to go there and fail a dozen times" is more 'fun' so we aren't going to get them :-(

[GoSlash27]

-->good advice<--

I would add that understanding the rocket equation and using it will make you a better engineer and will allow you to design much more efficient and capable vehicles than you could otherwise manage.

I'm a firm believer in working out the problems on your own early-on in order to further your understanding. You can work it on paper using a scientific calculator (or a slide rule, which is my preferred method) and then creating your own spreadsheet once you've gotten tired of doing it the hard way.

I'm kinda old- school when it comes to learning and I believe people learn best by doing.

Best,

-Slashy

[Red Iron Crown]

I say this as a calculating rocket scientist type:

Calculation is not necessary in KSP. Throwing parts together and hoping for the best is a perfectly valid play style.

[James_Eh]

I would add that understanding the rocket equation and using it will make you a better engineer and will allow you to design much more efficient and capable vehicles than you could otherwise manage.

I'm a firm believer in working out the problems on your own early-on in order to further your understanding. You can work it on paper using a scientific calculator (or a slide rule, which is my preferred method) and then creating your own spreadsheet once you've gotten tired of doing it the hard way.

I'm kinda old- school when it comes to learning and I believe people learn best by doing.

Best,

-Slashy

I tried to show my son how to use a slide rule once. We lost track of the decimal points and got an answer off by a factor of 100. And that, my friends, is why I have been using Excel for 26 years (which is awesome when you think about it).

[Pecan]

I tried to show my son how to use a slide rule once. We lost track of the decimal points and got an answer off by a factor of 100. And that, my friends, is why I have been using Excel for 26 years (which is awesome when you think about it).

Newb! You missed all the fun of Visicalc, 1-2-3, Supercalc, et al. {Started on the lecture circuit 1980 explaining the possibilities of spreadsheets and even, *gasp*, word processing}

[The_Rocketeer]

i say this as a calculating rocket scientist type:

Calculation is not necessary in ksp. Throwing parts together and hoping for the best is a perfectly valid play style.

verified fact.

[magnemoe]

I say this as a calculating rocket scientist type:

Calculation is not necessary in KSP. Throwing parts together and hoping for the best is a perfectly valid play style.

Yes, everybody started doing that, however it only takes you so far.

[thegab]

You don't need MJ to enjoy the game, I only use Kerbal engineer and i have been everywhere in the system. (because yes, it saves times to know your Dv before launching)

No need for auto pilot or any other cheat.

[Red Iron Crown]

Yes, everybody started doing that, however it only takes you so far.

For most players that's true (it certainly is for me). But I can think of a few long-time players here who play bone stock and rarely if ever calculate dV by hand, and they are able to pull off interplanetary missions. Some of them even claim part of the fun is not knowing whether their ship can complete the mission as designed, it adds to the tension.

I am firmly not in that camp, calculating dV and other things adds to the interest in designing for me and I manage to mess up enough missions without launching ones that are mathematically incapable of completion. Different strokes for different folks, and all that.

[Tery215]

dV is a measure of how much your spacecraft can accelerate. In an environment with nothing but your spaceship, you might be able to accelerate to 2,000 m/s before running out of fuel. So your ship's dV is 2,000 m/s. You could do something similar by editing a craft into orbit and doing a maneuver node with more dV requirement than your ship, then measuring how much dV is left in the maneuver node after you run out of fuel.

[James_Eh]

Newb! You missed all the fun of Visicalc, 1-2-3, Supercalc, et al. {Started on the lecture circuit 1980 explaining the possibilities of spreadsheets and even, *gasp*, word processing}

In the mid-80's my dad got Lotus something-or-other which included 1-2-3. I tried to type a high school essay on it, not realizing there was a word-processing application in there somewhere. Nearly soured me on computers forever. But this is veering off-topic...

[Rotsuda]

dV is a measure of how much your spacecraft can accelerate. In an environment with nothing but your spaceship, you might be able to accelerate to 2,000 m/s before running out of fuel. So your ship's dV is 2,000 m/s. You could do something similar by editing a craft into orbit and doing a maneuver node with more dV requirement than your ship, then measuring how much dV is left in the maneuver node after you run out of fuel.

I think you mean that Delta V is how much faster you can go than you're currently moving at. 2000 m/s delta V isn't 0-2000 m/s, it's "x" to +/-2000 m/s

so 2000 Delta V can either get you from 2000 m/s to 0, or from 2000 to 4000 (for example)

Or am I way off?

[Starman4308]

I think you mean that Delta V is how much faster you can go than you're currently moving at. 2000 m/s delta V isn't 0-2000 m/s, it's "x" to +/-2000 m/s

so 2000 Delta V can either get you from 2000 m/s to 0, or from 2000 to 4000 (for example)

Or am I way off?

Short answer: Yes, if you're thrusting prograde. It's better to think of it as "capacity to change velocity by 2,000 m/s", because that eliminates wonkiness with reference frames, the direction of your burn, and gravity.

Long answer: in the absence of other forces in a non-accelerating reference frame: yes. If your reference frame is Kerbin, and you are trying to get off the launch pad with a TWR of 1.01, you aren't going to be able to change your velocity much, because Kerbin surface gravity is eliminating 9.8 m/s per second of your upwards velocity, so you have to spend delta-V to replace the velocity lost to gravity drag.

Edited November 23, 2014 by Starman4308

[Yasmy]

For starters, I refuse to mod the game. A lot of the mods out there do look very shiny and attractive, but I'm a firm believer in using only what the game devs have provided ...

The game devs provided the mod system. Playing with mods is intended and supported behavior, and Squad often incorporates modders work directly into the game. I don't see any problem with people choosing to play stock. But saying that using a modded game is somehow different from playing the game the devs' intended or provided is clearly false.

[Specialist290]

Friendly Moderator Reminder: Whether or not it's "right" or "proper" to play with or without mods is a separate topic, and one that's often been contentious in the past at that. Let's not stray too far off-topic, folks