NathanKell

[1.2] Real Solar System v12.0 Dec 8

Recommended Posts

@Captain_Party: Your rockets are either unstable, or you make too large turns within the atmosphere, which when using FAR WILL cause the rocket to flip-out. Make smaller turns(do not leave the surface speed prograde marker while in the atmosphere).

The second problem might be a MechJeb problem, or it is displaying your delta-v wrong.

They are too powerful, especially in the atmosphere. Small and gradual movements. Place fins at the bottom of a rocket to help stabilize it into the stream. Controllable fins. Use fine controls. Do gradual gravity turns. And start them early, keep your speed in lower atmosphere low too.

Share this post


Link to post
Share on other sites

Hey guys, is the GEO orbit height still the same? if not does anybody know where it is or how to calculate it? Sorry if this has been asked already, but I read the whole OP and couldn't find this information. Would be nice if OP could add this.

Share this post


Link to post
Share on other sites
Hey guys, is the GEO orbit height still the same? if not does anybody know where it is or how to calculate it? Sorry if this has been asked already, but I read the whole OP and couldn't find this information. Would be nice if OP could add this.

http://en.wikipedia.org/wiki/Geostationary_orbit

Share this post


Link to post
Share on other sites
[*]I only need 3km of delta-v to get into orbit. Mechjeb just stops at 300km up, to coast to apoapsis..

Wait... you meant "need 3km of deltaV to get into space". What you need for a circular orbit is around 9.5km/s.

Share this post


Link to post
Share on other sites
So is the GEO orbit height of the Earth and rescaled Kerbin the same?

Rescaled Kerbin has the same radius (6,371km), same mass and the same rotational period (23h 59m 4s) like Earth. The GEO orbit is thus the same.

Just be aware that for some calculations you have to account for Earth radius into factor, like for example, determining the distance between two satellites in GEO (in this case the orbit measured from the center of Earth will be 42,157km).

Edited by SFJackBauer

Share this post


Link to post
Share on other sites

Does "35,786" (from the first sentence in that linked article) look like "2868" to you? ;)

XNerd_Bomber, MFT aka MFS is Modular Fuel System. See link in sig. It gives you realistic tanks and engines.

Captain_Party: I have the same setup so I don't think there's anything inherently wrong. Launching with FAR is different so you have to get used to the new way to fly. Make sure your rocket has CoL well behind CoM (add fins to further stabilize), start turn when <= 100m/s velocity, and turn gradually until about 100km alt. Make sure you're never pointed more than 3-5degrees off the surface-prograde indicator.

Share this post


Link to post
Share on other sites

It's the fuel tanks from the stretchy SRB pack. When I use KW Rocketry fuel tanks, it's as straight as an arrow, however with ST, like a wobbly rocket. On steroids. I love my ST's can anyone help?

EDIT: Is there anyway I can launch with MJ?

Share this post


Link to post
Share on other sites
It's the fuel tanks from the stretchy SRB pack. When I use KW Rocketry fuel tanks, it's as straight as an arrow, however with ST, like a wobbly rocket. On steroids. I love my ST's can anyone help?

EDIT: Is there anyway I can launch with MJ?

MJ: probably but you have little room for error. When I tried the earlier versions of this I got very close to a stable orbit with MJ. but not quite. With a better rocket or better parameters or both I think it could do it. As it was I had to take over approaching edge of atmo to make orbit.

Edit: actually I think I'm forgetting to account for atmospheric issues in the early versions... Not sure what difference that makes.

Share this post


Link to post
Share on other sites
It's the fuel tanks from the stretchy SRB pack. When I use KW Rocketry fuel tanks, it's as straight as an arrow, however with ST, like a wobbly rocket. On steroids. I love my ST's can anyone help?

EDIT: Is there anyway I can launch with MJ?

Here, I just put this together with StretchyTanks (latest version V5), ProcFairings and KW. The payload is a small satellite. Enough DV for a 300km orbit at max. Be sure to also use KerbalJointReinforcement.

Just launched with MJ with:

Turn start 0.2

Turn end 120km

Final path 0

Grade 50%

Orbit - set between 150 and 300, atmosphere ends at 105.

Dont even worry about throttle settings, leave all off.

Download Craft file

S3UE8qb.png

Share this post


Link to post
Share on other sites
MJ: probably but you have little room for error. When I tried the earlier versions of this I got very close to a stable orbit with MJ. but not quite. With a better rocket or better parameters or both I think it could do it. As it was I had to take over approaching edge of atmo to make orbit.

Edit: actually I think I'm forgetting to account for atmospheric issues in the early versions... Not sure what difference that makes.

You can launch with MJ very well. Start gravity turn early at around 200m, end at 80-100km. Depending on the TWR of the rocket, the shape may go from 70 to 40 or so. If you've got a lot of TWR make the turn sharper because it's gonna be next to impossible to turn the rocket any significant amount once it goes supersonic.

Share this post


Link to post
Share on other sites

Thanks all so much. Finally got it non-wobbly. The rocket ypu built for me is great, just "subassemblied" it. I find putting final path angle as 10 degrees on top of everything else gives you a a nice, flat orbital trajectory, with MJ about 5 minutes ago I did it and it cost me 7 and a half km of delta-v, so its pretty effective.

EDIT: Just a heads up, the decouplers frpm the rocket are from AIES, lucky I had it installed ;)

Edited by Captain_Party

Share this post


Link to post
Share on other sites
Atmosphere is always blueish from the surface due to the basic physics - the effect is known as Rayleigh scattering.

Yeah, last I checked NASA's Mars surface pics only showed red skies after manual color adjustment. The raw pictures had blue skies.

Share this post


Link to post
Share on other sites
@Captain_Party: Your rockets are either unstable, or you make too large turns within the atmosphere, which when using FAR WILL cause the rocket to flip-out. Make smaller turns(do not leave the surface speed prograde marker while in the atmosphere).

The second problem might be a MechJeb problem, or it is displaying your delta-v wrong.

They are too powerful, especially in the atmosphere. Small and gradual movements. Place fins at the bottom of a rocket to help stabilize it into the stream. Controllable fins. Use fine controls. Do gradual gravity turns. And start them early, keep your speed in lower atmosphere low too.

I'm about to try this again with FAR. I tend to run into the same problem; would it help to stay below terminal velocity?

You can launch with MJ very well. Start gravity turn early at around 200m, end at 80-100km. Depending on the TWR of the rocket, the shape may go from 70 to 40 or so. If you've got a lot of TWR make the turn sharper because it's gonna be next to impossible to turn the rocket any significant amount once it goes supersonic.

Thanks for the input, I'll keep this in mind.

Edited by Starwaster

Share this post


Link to post
Share on other sites
Yeah, last I checked NASA's Mars surface pics only showed red skies after manual color adjustment. The raw pictures had blue skies.

Another example I'd forgotten was Hubble. Hubble shots of Mars show it to be definitely tinged in blue on the edges of the planet. The same as Earth appears from orbit with that blue haze.

Share this post


Link to post
Share on other sites
I did it and it cost me 7 and a half km of delta-v, so its pretty effective.

That's impossibly efficient.

Share this post


Link to post
Share on other sites

@Starwaster: With FAR terminal velocity (for a fully fueled rocket) is supersonic at sea level--you'd have a lot of trouble getting above terminal velocity to begin with. If you are somehow capable of getting above terminal velocity with FAR, it means that you're bringing too much engine for your rocket. Going "slower" in the lower atmosphere with FAR basically means "don't outrun the control authority of your engine / don't let aerodynamic forces shred it."

If you're using MFS with real fuels, I've found that a good just-barely-gets-to-orbit rocket is a modified form of the Kerbal X:

Remove the landing legs from the orbiter; set the engine to use N2O2 and MMH; fill that tank with that blend.

Take off the booster below that and put it to the side.

Put an orange fuel tank below the orbiter stage and put a Skipper below that; set it to run on LH2 and LOX; fill the tank with that blend.

Reattach the remainder of the stock Kerbal X below it; mess with the staging so it work right.

To fly it, start to pitch over once it's going ~60 - 100 m/s; don't be afraid, its TWR shoots up once the asparagus boosters empty. Don't use SAS, and just make sure that it's pointing forward while in the atmosphere.

@asmi: I agree; 7.5 km/s dV is needed for orbiting alone below ~300km; some extra must have been lost to gravity and drag.

Share this post


Link to post
Share on other sites
I'm about to try this again with FAR. I tend to run into the same problem; would it help to stay below terminal velocity?

Make sure to have this option off in MJ if you use FAR since MJ has no idea about real terminal velocity.

Share this post


Link to post
Share on other sites
Thanks all so much. Finally got it non-wobbly. The rocket ypu built for me is great, just "subassemblied" it.

Glad it worked for you! I know the feeling of "launch something to orbit" is important, now you go and hopefully build your own :)

EDIT: Just a heads up, the decouplers frpm the rocket are from AIES, lucky I had it installed ;)

You're right, I fixed and re-uploaded the file.

I did it and it cost me 7 and a half km of delta-v, so its pretty effective

You must be quoting the surface speed indicator. Since the rocket had 9.5km/s you lost up to 2km/s to gravity and drag, depending on the amount of propellant left in the last stage.

Make sure to have this option off in MJ if you use FAR since MJ has no idea about real terminal velocity.

It actually doesn't matter since MJ always thinks it is zero with FAR. It does not mess the throttle. But yeah its a good idea to leave it off to alleviate confusion.

Edited by SFJackBauer

Share this post


Link to post
Share on other sites

looks to take about 9000dV to get to orbit. Takes about 3200dv to transfer to the mun. Unknown how much to circularize around mun. Haven't gotten that far yet.

Share this post


Link to post
Share on other sites
looks to take about 9000dV to get to orbit. Takes about 3200dv to transfer to the mun. Unknown how much to circularize around mun. Haven't gotten that far yet.

Took around...700m/s of delta-v for me IIRC? (If we're talking 20km or so high orbits anyway.)

Of course, this may or may not be a major issue for my Apollo 11 mission using Sumghai's service module for the C/SM because it turns out I underjudged how much of an effect the lander's mass would have and I'm not sure if I have enough delta-V to even just return to a Kerbin orbit, much less come back on a reentry trajectory.

Probably should have seen that coming now that I think about it, since my C/SM had around 1,800 m/s of delta-v compared to the Apollo CSM's 2,800 m/s...

And on a sidenote towards NathanKell or anybody else who might be knowledgeable about it, what can I edit in the v5 configs so I can keep Minimus in the current orbit it's got in my save with v4?

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.