areoassist question

[SpaceSphereOfDeath]

Is the whole concept of an areoassist really worth it (for those who don't know, an areoassist is where a space craft enters an atmosphere and using wings, picks up more velocity then it had before), I mean is it really worth hauling out some wings just to gain about 80m/s of deltaV? Or should you just use rocket engines.

(I'm asking because I think I want to do a double areoassist mission to laythe to say goodbye to my save;.

[stupid_chris]

Is the whole concept of an areoassist really worth it (for those who don't know, an areoassist is where a space craft enters an atmosphere and using wings, picks up more velocity then it had before), I mean is it really worth hauling out some wings just to gain about 80m/s of deltaV? Or should you just use rocket engines.

(I'm asking because I think I want to do a double areoassist mission to laythe to say goodbye to my save;.

I don't know if that can be done well in KSP with this crappy aerodynamics model. But I'm not in the knowledge of that technique, but perhaps it could be interesting! I think you should try it at least Even if it's not worth it in the end, it's probably gonna be a bunch of fun. Disregard physics, acquire flight.

[SpaceSphereOfDeath]

Thanks, I think the only time NASA ever considered it was for future space flight, ie space tourism.

I'll still try

[zerotwo]

If you mean to dip into an atmosphere to gain speed, I am almost one hundred percent certain you will lose speed, not gain any.

If you were to bring air intake engines that could move your vessel on a flight to Jool or Eve's, dip in to the atmosphere and begin to accelerate, you could definitely gain a ton of efficient delta-v through that approach.

Would be a hell of a thing to prototype. (As this is what I am currently working on)

[Chrisd857]

Well, it is a thing: Aerogravity assist

[stupid_chris]

If you mean to dip into an atmosphere to gain speed, I am almost one hundred percent certain you will lose speed, not gain any.

If you were to bring air intake engines that could move your vessel on a flight to Jool or Eve's, dip in to the atmosphere and begin to accelerate, you could definitely gain a ton of efficient delta-v through that approach.

Would be a hell of a thing to prototype. (As this is what I am currently working on)

Aeroassist reposes on using the lift provided at high speeds by skimming the low density parts of an atmosphere, and yes it does allow you to gain some speed. And no, there is no intake air excepted on Kerbin and Laythe, this won't work on Jool.

An aeroassisted mission uses atmospheric forces to effect a spacecraft delta-V, which could allow for substantial propellant savings.

[purpletarget]

I'd be careful about associating delta-v effects as the same thing as gaining speed.

From the link provided, it looks that the Aero part is an additional component to a gravity assisted turn, where atmo allows a sharper turn than would be provided by gravity alone. This sharper change in direction, without atmo would otherwise require additional dV on the s/c.

From the brief description given, I don't see anything that would indicate an increase in the actual velocity, other than that which might be provided from the gravity assist. Otherwise, the aero component can only add drag.

[stupid_chris]

I did a quick research on it, there's not much talk about it honestly. Wikipedia has references those are red (or blank references), so yeah, it's probably not as discussed as the other atmospheric skimming techniques. I won't advance myself too far on it, but IIRC, by getting enough lift, you could somehow "bounce" off the atmosphere and gain a significant amount of speed.

[maltesh]

Aerobraking results in bring your spacecraft's velocity around the sun /closer/ to the velocity of the object you're braking against. When a spacecraft going from Kerbin to , say, Duna aerobrakes in Duna's atmosphere, the spacecraft's sun-relative velocity is /increased/ by the atmospheric friction.

[Sathurn]

You are not going to gain speed entering the atmosphere. Using DRAG you can get a DV in the direction opposite of travel. Using a lifting body you can get DV perpendicular to the direction of travel with some drag. But you can not accelerate in the tradition use of the word (AS in increase your speed in the direction of travel).

[zerotwo]

Fascinating.

I just didn't think KSP would allow this kind of thing to function... hmmm...thank you stupid_chris, and sorry SpaceSphereofDeath, I will have to find out if this works.

I think I can visualize how this would work... also, thanks for adding to my knowledge regarding Oxygen content on those worlds, I don't know where I got that into my head.

Off to Laythe then.

Edited July 19, 2013 by zerotwo
additional thoughts

[Nao]

For people wanting to experiment aero-slingshooting in KSP i have bad news that the current aerodynamic model have drag forces proportional to square of speed but lift is directly proportional to speed. That means lift is very weak in upper atmosphere and unless we gain a lot from turning our trajectory that several degrees more we will lose more to drag than gained.

This would probably work quite well with Ferram mod, as there it's possible to keep great speeds at quite low altitudes. So not only we gain from lift but also from closer proximity to the planet during the pass.

Cheers!