Duna Direct (pic heavy)

[Brotoro]

No, I've never noticed it affecting my performance. I do use the lower-res textures.

[Zephram Kerman]

In the Mars Direct plan, the Habitat Unit is supposed to be separated from its transfer stage with the two sections connected together by a long cable. The two sections can then be spun around the common center of mass to provide artificial gravity. I don't have any mod for this cable, but I have represented it below with a little work in Photoshop. For the shorter trip required in the diminutive KSP system, I suppose they wouldn't bother with this. Also, I intend to use the transfer stage for some small orbital maneuvers at Duna, so I'd have to reel it back in later and re-dock it for any burns.

http://i.imgur.com/L9CZHYq.jpg

Since I just now finally am experimenting with KAS, thought I'd try out the gravity cable idea in KSP. Wow, it's tricky. Not sure I would want to stake my real life on any cable.

Anyway, my physics training has about 20 years of rust. Would anyone care to help with this? From Wikipedia:

So if I want 0.1 G and the cable in KAS is limited to only 50 m, that means

w = √r/a (What's the ascii code for little omega?)

Therefore, angular velocity should be 22-ish. But, is that degrees, radians, or elbows? While 22°/sec would be only a little bit nauseating, 22 radians/sec would make for some really blurry screenshots. And 22 elbows/second, well that's just crazy.

Also, bear in mind r is not the 50 m cable. It's the distance from center of rotation to the floor of a landercan. But let's just assume 50 m for now. Or, maybe I'll hack KAS to allow longer cables.

Too bad the accelerometer in game cannot detect centripetal acceleration, only the acceleration of the whole vessel. So all of this can only be verified mathematically.

[Brotoro]

Omega is in radians per second... but I think you are calculating something incorrectly. If you want a=0.1g=0.981 m/s², and you have a 50 meter cable (r=25 m), then

ɲ = a/r = 0.981/25 = 0.039

̉ۡ = 0.198 radians/sec

which is about 1.89 rotations per minute.

(Unless I've calculated something wrong.)

[Zephram Kerman]

Aha, I see I had the a/r inverted. Very rusty, indeed. Well, 1.89 RPM doesn't sound so bad. Thank you.

If you're still interested, here's a vid I did yesterday while experimenting with the gravity cable idea. Spun up a craft to about 4 RPM. The KAS cable didn't work well at all; once spinning, the system would twist and then precess wildly. But when I used that cable temporarily to assist with installing a pipe, things worked much better. I suppose the KAS struts would do the same.

https://dl.dropboxusercontent.com/u/78157466/CableGrav%20test%202.wmv

Making the counterweight heavier than the crew area helped to increase the radius.

[Brotoro]

Aha, I see I had the a/r inverted. Very rusty, indeed. Well, 1.89 RPM doesn't sound so bad. Thank you.

If you're still interested, here's a vid I did yesterday while experimenting with the gravity cable idea. Spun up a craft to about 4 RPM. The KAS cable didn't work well at all; once spinning, the system would twist and then precess wildly. But when I used that cable temporarily to assist with installing a pipe, things worked much better. I suppose the KAS struts would do the same.

https://dl.dropboxusercontent.com/u/78157466/CableGrav%20test%202.wmv

Making the counterweight heavier than the crew area helped to increase the radius.

Very cool video! Is that the cable, or the pipe? That seems to be a much faster rotation rate then you'd need for a reasonable artificial gravity.

[Zephram Kerman]

Thanks! In the video, it's the pipe. In hindsight, I probably should have started recording with the cable, just to show the weird way it acts. Maybe next time. The rotation rate was very arbitrary; simply the maximum I was able to achieve with RCS thrusters and ASAS.

You bring up an interesting point. How much artificial gravity is "reasonable"? I set 0.1 G as an arbitrary target. But, for humans, how much is needed to avoid physiological issues like muscle atrophy, bone density loss, constant sinus infections, etc?