Does Aerodynamics matter for launches?

[Horman]

Hi,while watching some youtube tutorial and Let's Plays, I was wondering, that no one was using some kind of "nose-cones" for their rockets.Is that right or were those filmmakers just "lazy"?

Edited September 15, 2013 by Horman

[Dart980]

Right now nosecones only add more drag and weight to your rocket which reduces perfomance and Delta-V. Only use them if you have FAR.

[shand]

Dart is right - though i would add that they make the rockets look prettier!

We are expecting (in the long run) an aero overhaul which will make aero important.

At the moment aerodynamic drag is defined by a drag constant for each part (listed in the VAB for most parts) multiplied by its mass - So a full fuel tank will have more drag than an empty one - which is clearly a bit wrong, but its what we have to work with for now

[SRV Ron]

So far, other then fins, they have no aerodynamically effect and only add drag and weight. In the future, they will be important.

[blizzy78]

Personally I've switched to using fairings all the time (with the Procedural Fairings mod) just for the looks. I'm ignoring nosecones, though

[Geschosskopf]

As others have said, nosecones at present are counterproductive. However, to answer the general question of the thread's title, yes, aerodynamics DO matter for launches, even in the present state of the game, even without FAR. However, this is only to a limited extent.

First off, you need some way of generating control forces to during launch so you can do the gravity turn. IMHO the best way to do this is with aerodynamic control surfaces. Reaction wheels (unless you have literally tons and tons of them) aren't enough to turn big rockets, RCS works fine but requires lifting its fuel, and thrust vectoring is NOT a precision control system and has a strong tendency to introduce wobble. Control surfaces OTOH are light, powerful, and precise.

Second, there's the case where you're sending an airplane to another planet and want to launch it vertically atop a rocket because you hate messing with SSTO spaceplanes. But the more lift the plane has, the stronger the off-center force it creates on the rocket as the rocket's speed increases. Up to a point, you can still launch this way but in extreme cases, the lift will either break the plane off the rocket or, if you strut the bejeezus out of it, pull the whole rocket over. So if you run into this issue, you either have to build a really strange rocket around the airplane, using the plane's wings as the rocket's tail fins, or give up and go the spaceplane route anyway.

[magnemoe]

For launching the spaceplane on top of rocket, could you not add wings on the rocket to counter the planes lift?

One aerodynamic issue is lander designs. if you have lots of struts and stuff in bottom of an lander it might want to go down nose first this can make an powered landing on Laythe hard, an braking parachute usually solves this.

[shand]

the effect of wings on transporting spaceplanes on rockets is all about angle of attack, to see if your launch will be effected, and how, angle your rocket in the VAB, you'll find if your rocket points straight up its fine, but any variation will lead to a positive feedback loop. slight angle of attack -> "lift" from wings ->pushes the nose further from prograde -> larger angle of attack.

to compensate either place symetrical (or near enough) wings that you can decouple, or place aero at the base of your rocket to have a controlling effect.

[Dart980]

As others have said, nosecones at present are counterproductive. However, to answer the general question of the thread's title, yes, aerodynamics DO matter for launches, even in the present state of the game, even without FAR. However, this is only to a limited extent.

First off, you need some way of generating control forces to during launch so you can do the gravity turn. IMHO the best way to do this is with aerodynamic control surfaces. Reaction wheels (unless you have literally tons and tons of them) aren't enough to turn big rockets, RCS works fine but requires lifting its fuel, and thrust vectoring is NOT a precision control system and has a strong tendency to introduce wobble. Control surfaces OTOH are light, powerful, and precise.

Second, there's the case where you're sending an airplane to another planet and want to launch it vertically atop a rocket because you hate messing with SSTO spaceplanes. But the more lift the plane has, the stronger the off-center force it creates on the rocket as the rocket's speed increases. Up to a point, you can still launch this way but in extreme cases, the lift will either break the plane off the rocket or, if you strut the bejeezus out of it, pull the whole rocket over. So if you run into this issue, you either have to build a really strange rocket around the airplane, using the plane's wings as the rocket's tail fins, or give up and go the spaceplane route anyway.

I was speaking only about nosecones and size adapters. Wings and other aerodynamic surfaces are useful in rockets.