KSP Orbital Calculator [V0.10.1] - Now with selectable Celestrial Bodies

[Warringer]

That explains that then... >_>

I know that something was bugging me...

Okay, off to correct that long oversight of my program... >_<

[MaxSchram]

Why don't you finish that experimental launch orbit section in your calculator? It would be really usefull, because often one wants to determine (especially after launch) when, where and at what speed im going to reach apogee / perigee. Also in situations where one wants to change orbit, somewhere between the two hotspots, it could be utilized.

But that tools doesn't seem to produce valuable results, no matter what i typed in the fields. In particular the velocity vector isn't clear at all. Do you use some vector notation, or is it an angle relative to the navball (degrees or radians?).

I would appreciate further improvements.

[foamyesque]

That explains that then... >_>

I know that something was bugging me...

Okay, off to correct that long oversight of my program... >_<

Man, I told you that ages ago. =(

[MaxSchram]

While testing around with different propulsion configurations i noticed that your calculation of the specific impulse is not correct. Please don't take me wrong, i'm not sitting here, trying to find bugs and complain about them. I just want that such a nice tool like the Orbital Calculator provides correct results.

The formula for the specific impulse at see level is:

Isp = Fthrust / (q * g0)

With q being the mass flow and g0 the standard gravity. For a standard rocket (Pod, SAS, LFT, LFE) the mass flow is q = 2.2e3 kg / 62.5 s = 35.2 kg/s and the thrust Fthrust = 200kN. Which leads to a specific impulse Isp = 579.19 s, which is alot less than your result.

The Tsiolkovsky Rocket Equation to calculate the delta-v value says:

dV = Isp * g0 * ln(m0 / m1)

with m0 being the initial mass and m1 the mass at burnout.

Continuing the former example and setting m0 = 6.3e3 kg and m1 = 4.1e3 kg, the final amount of delta-v is dV = 2439.86 m/s.

Btw: You misscorrected your delta-v calculations, it now shows something about 23km/s for the same example

[foamyesque]

I think a lot of this confusion is my fault. I built a spreadsheet that Warringer used as the basis of his dV stuff and I labelled exhaust velocity as 'SI' because I knew what I meant.

I've tried to explain this but I think there was a misunderstanding somewhere. =(

[Warringer]

While testing around with different propulsion configurations i noticed that your calculation of the specific impulse is not correct. Please don't take me wrong, i'm not sitting here, trying to find bugs and complain about them. I just want that such a nice tool like the Orbital Calculator provides correct results.

The formula for the specific impulse at see level is:

Isp = Fthrust / (q * g0)

With q being the mass flow and g0 the standard gravity. For a standard rocket (Pod, SAS, LFT, LFE) the mass flow is q = 2.2e3 kg / 62.5 s = 35.2 kg/s and the thrust Fthrust = 200kN. Which leads to a specific impulse Isp = 579.19 s, which is alot less than your result.

The Tsiolkovsky Rocket Equation to calculate the delta-v value says:

dV = Isp * g0 * ln(m0 / m1)

with m0 being the initial mass and m1 the mass at burnout.

Continuing the former example and setting m0 = 6.3e3 kg and m1 = 4.1e3 kg, the final amount of delta-v is dV = 2439.86 m/s.

Btw: You misscorrected your delta-v calculations, it now shows something about 23km/s for the same example

I know, I missed to make a change in one place and just remembered yesterday when I went to bed... >_<

I think a lot of this confusion is my fault. I built a spreadsheet that Warringer used as the basis of his dV stuff and I labelled exhaust velocity as 'SI' because I knew what I meant.

I've tried to explain this but I think there was a misunderstanding somewhere. =(

Perhaps we were both at fault.

[McLuv]

Could you get another setting made for the eliptic orbit calculator? If you're still in transit between apoapsis and periapsis, it should be possible with the ground angle (+/- for above/below horizon) and altitude to determine the rest of the trajectory, should it not?

Also the visual projection often doesn't show anything accurately unless apo- and periapsis have a very large difference.

[Saaur]

To go back to the Launch Orbit section, how does one use the velocity vector?

Degrees from vertical, or what?

[General Buttercrust]

I hate to sound like the newbie that I am to computer programs and such, but I've downloaded the calculator, where do I put it?

EDIT: Spelling.

[foamyesque]

Anywhere you can find it again, it's a standalone program. I have it in \Kerbal\KSPCalc, so it's in the same directory as various versions of the game [\Kerbal\85\, Kerbal\90], but it comes down to personal preference.

[General Buttercrust]

Anywhere you can find it again, it's a standalone program. I have it in \Kerbal\KSPCalc, so it's in the same directory as various versions of the game [\Kerbal\85\, Kerbal\90], but it comes down to personal preference.

Thanks again!

[Warringer]

Could you get another setting made for the eliptic orbit calculator? If you're still in transit between apoapsis and periapsis, it should be possible with the ground angle (+/- for above/below horizon) and altitude to determine the rest of the trajectory, should it not?

Also the visual projection often doesn't show anything accurately unless apo- and periapsis have a very large difference.

Well, that is because of the actual drawing of the orbit. Its not scaled to anything, only zoomed in/out when needed to display the orbit.

A bit stupid to try and display an elliptic orbit of 40km/41km, isn't it?

[McLuv]

That`s not what I mean, I mean the accuracy compared to the planet in the middle. Look at the attached file.

Also, what do you think about using Angle+Altitude+velocity for eliptical orbit calculations?

E: The Apo in the pic to the right incorrectly says '40', it should say '50'

The only reason i say this is that I use it also to estimate how far into my orbit i have until i hit the atmosphere

[rdfox]

Hey, I just had an idea for a feature suggestion that I don't *think* would be too difficult to code.

Could you give us a toggle to let us reverse the order in which stages are computed in the multi-stage calculator? It would make it easier to attempt to calculate a booster's delta-vee with various payloads, since we could just delete the payload stage at the bottom of the list and add a new one, instead of having to reconstruct the entire rocket. (It would also make it easier to sanity-check new upper stages for a design, for the same reason--you could just delete the payload stage, then install the planned upper stage and a new payload stage.)

[Warringer]

That`s not what I mean, I mean the accuracy compared to the planet in the middle. Look at the attached file.

Also, what do you think about using Angle+Altitude+velocity for eliptical orbit calculations?

E: The Apo in the pic to the right incorrectly says '40', it should say '50'

The only reason i say this is that I use it also to estimate how far into my orbit i have until i hit the atmosphere

Considering that the graphic tool was pretty much cludged together, there are bound to be some bugs like that. I will eventually get to it to fix it.

Hey, I just had an idea for a feature suggestion that I don't *think* would be too difficult to code.

Could you give us a toggle to let us reverse the order in which stages are computed in the multi-stage calculator? It would make it easier to attempt to calculate a booster's delta-vee with various payloads, since we could just delete the payload stage at the bottom of the list and add a new one, instead of having to reconstruct the entire rocket. (It would also make it easier to sanity-check new upper stages for a design, for the same reason--you could just delete the payload stage, then install the planned upper stage and a new payload stage.)

I used to have an edit button for the stages. Still need to reprogram the edit feature.

[RangerDanger75]

I was using the stage calculator when I had an idea for the calculator. Instead of giving us parts to pick and choose, why not just let us input the stage weight and thrust values ourselves? Especially now that we have tooltips in game that display the information. This would let us use the calc for non-vanilla rockets.

[Warringer]

I was using the stage calculator when I had an idea for the calculator. Instead of giving us parts to pick and choose, why not just let us input the stage weight and thrust values ourselves? Especially now that we have tooltips in game that display the information. This would let us use the calc for non-vanilla rockets.

If you go into the 'Calculator' Menu and select 'Configuration' you can point the calculator to the main KSP directory. That way the calculator will read out all your custom parts when you start the program again.

[foamyesque]

* Altimeter is registering 60m when landed at sea level

- Added 60m to the reported planet radius, and now the altimeter is properly calibrated again. This might have a very slight impact on gravity decay and things, but very negligible given that this is a 0.0001% change in radius. Also, it should be more accurate this way.

I haven't hit orbit in .10x yet, been trying with other things, but can someone check on this?

[Xivios]

Seen you from the other topic. I haven't DL'd the experimental version, but I wouldn't be surprised if that is indeed the cause of the problem. I'm fairly certain Harvester's math is two orders of magnitude off. A 60m radial increase is small, but Kearth is a small planet. 60 meters on 600,000 doesn't seem like much, but it's 0.01% bigger, not 0.0001%. And a 0.01% difference can make a big difference in orbit.

[DoctorEvo]

I haven't hit orbit in .10x yet, been trying with other things, but can someone check on this?

Sorry Foamy, but even I'm not good enough to nail down my orbit to within 60 meters.

[rdfox]

Remember, NASA considers an eccentricity of five miles in a 200-mile orbit (0.005, I think?) to be 'circular.' Maintaining an orbit to within 60 meters is as unrealistic as Frank Borman having wanted NASA to make sure that Apollo 8 maintained a trajectory within 3 feet per second of a true free-return trajectory before Lunar Orbit Insertion, just in case the SPS engine crapped out on a mission with no backup.

There's a point where you've gotta stop trying to polish the cannonball and say, 'Eh, close enough.'

[Warringer]

Even if there was any problem, it would only be needed to change a single constant... Two seconds tops.

[sirscott]

I just wanted to stop by and thank everyone involved with the production of this calculator. It has really improved the game for me , and the life expectancy of my kerbals!

[rdfox]

New glitch, this time in the stage calculator and multi-stage calculator. The bottom edge of the panel for selecting parts in the window doesn't extend to the bottom of the full list, if you have a lot of parts in your parts folder; for example, I currently have enough propulsion parts that it goes to five propulsion tabs, with two parts on the last tab... and the bottom 'two and a half' parts on each tab are below the bottom of the 'panel' and cut off so I can't see them. (The two bottom ones are, and the lowest one displayed is only halfway on the 'panel'.) This effectively leaves you unable to select some of your parts for calculation...

[Warringer]

New glitch, this time in the stage calculator and multi-stage calculator. The bottom edge of the panel for selecting parts in the window doesn't extend to the bottom of the full list, if you have a lot of parts in your parts folder; for example, I currently have enough propulsion parts that it goes to five propulsion tabs, with two parts on the last tab... and the bottom 'two and a half' parts on each tab are below the bottom of the 'panel' and cut off so I can't see them. (The two bottom ones are, and the lowest one displayed is only halfway on the 'panel'.) This effectively leaves you unable to select some of your parts for calculation...

Hmmm... I will look into it...