interplanetary angles

[ray.mcdonough]

Alright,

I get the 'Interactive illustrated interplanetary guide and calculator for KSP' and I know how to get the angles. I've been able to eye-ball Duna intercepts.

You see, I got gun-shy when my three-hundred hour career glitched permanently, and I suspected mod conflicts. It was mostly my fault, because I had deleted all my saves, but still, I decided to see If I couldn't do everything vanilla.

My question is; is there any way outside of just eyeballing it to check the numbers on the phase and ejection angles?

[Jupiter3927]

Short answer is not really.
Long answer is you can estimate.

You could get an accurate estimate for all planets except Moho, Dres and Eeloo due to the high eccentricities.
That fancy law of cosines equation can be played with to give the angle between planets.

c^2 = a^2 + b^2 - 2ab*cos(d)

Where A, B and C are distances and D is the angle you want, in this case the phase angle.
Play with it and you get...

cos-1((c^2-a^2-b^2)/(-2ab)) = d

A is going to be the distance from one planet to the sun.
B is going to be the distance from the other planet to the sun.
C is the distance between planets.
D is your estimated phase angle.

Or you could use mods to figure it out, but that's no fun.

[ray.mcdonough]

Originally posted by Jupiter3927:

Short answer is not really.
Long answer is you can estimate.

You could get an accurate estimate for all planets except Moho, Dres and Eeloo due to the high eccentricities.
That fancy law of cosines equation can be played with to give the angle between planets.

c^2 = a^2 + b^2 - 2ab*cos(d)

Where A, B and C are distances and D is the angle you want, in this case the phase angle.
Play with it and you get...

cos-1((c^2-a^2-b^2)/(-2ab)) = d

A is going to be the distance from one planet to the sun.
B is going to be the distance from the other planet to the sun.
C is the distance between planets.
D is your estimated phase angle.

Or you could use mods to figure it out, but that's no fun.

OK, I'm suitably impressed, but I'm no math wiz.

Are you saying that it's not possible to go interplanetary to those outer planets in KSP without mods? I wouldn't think so.

[Jupiter3927]

It's not explicitly given but distances are given no problem as long as you have a craft near at least 1 of the planets.

The math is basic geometry any scientific calculator can do.
Just flip the calculator on your computer to 'scientific' if you don't have one lying around somewhere.

[Cato]

Originally posted by Jupiter3927:

Short answer is not really.
Long answer is you can estimate.

You could get an accurate estimate for all planets except Moho, Dres and Eeloo due to the high eccentricities.
That fancy law of cosines equation can be played with to give the angle between planets.

c^2 = a^2 + b^2 - 2ab*cos(d)

Where A, B and C are distances and D is the angle you want, in this case the phase angle.
Play with it and you get...

cos-1((c^2-a^2-b^2)/(-2ab)) = d

A is going to be the distance from one planet to the sun.
B is going to be the distance from the other planet to the sun.
C is the distance between planets.
D is your estimated phase angle.

Or you could use mods to figure it out, but that's no fun.

I think I am going to save this answer somewhere because I might have understood that. - Im gonna go get the distances

[Cato]

So In my game Currently:

A= 13.3M (Kerbin)
B= 21.3M (Duna)
C= 33.6M Distance between
D = angle

cos -1 ((33.3^2 - 13.3^2 - 21.3^2 ) / (-2 x13.3x21.3)) = -0.87949

I have no idea what angle thats supposed to be

[Jupiter3927]

I did that exact same equation...

Originally posted by Cato:

So In my game

A= 13.3M (Kerbin)
B= 21.3M (Duna)
C= 33.6M Distance between
D = angle

cos -1 ((33.3^2 - 13.3^2 - 21.3^2 ) / -2 x13.3x21.3)) = -0.87949

I have no idea what angle thats supposed to be

...and got 151.6 degrees for the phase angle.

You did the cosine inverse function right?
Not the cosine value of -1 * all that stuff?

[ray.mcdonough]

Originally posted by Jupiter3927:

I did that exact same equation...

Originally posted by Cato:

So In my game

A= 13.3M (Kerbin)
B= 21.3M (Duna)
C= 33.6M Distance between
D = angle

cos -1 ((33.3^2 - 13.3^2 - 21.3^2 ) / -2 x13.3x21.3)) = -0.87949

I have no idea what angle thats supposed to be

...and got 151.6 degrees for the phase angle.

You did the cosine inverse function right?
Not the cosine value of -1 * all that stuff?

This is all very impressive, guys, but you failed to answer my op question; I didn't ask how to do the math, I have that calculator to do it for me. Sort of like for real.

What I asked was how do you tell the angles are right in the vanilla game, beyond the Mark I eyeball?

Well, Jupe probably answered it.

[ray.mcdonough]

I mean, do I have to get my Speed Square from the garage, and stick it on my sceen?

[Cato]

Originally posted by ray.mcdonough:

Originally posted by Jupiter3927:

I did that exact same equation...



...and got 151.6 degrees for the phase angle.

You did the cosine inverse function right?
Not the cosine value of -1 * all that stuff?

This is all very impressive, guys, but you failed to answer my op question; I didn't ask how to do the math, I have that calculator to do it for me. Sort of like for real.

What I asked was how do you tell the angles are right in the vanilla game, beyond the Mark I eyeball?

Well, Jupe probably answered it.

Oh silly me its shift cos :P (thanks btw)

Ray heres a trick I learned; draw a line from the lower planet to the upper planet (so from Kerbin to Duna) if it is possible to draw a straight line from Kerbin to Duna that is parallel to the sun - then the transfer window exists

[Kinote]

Hold a protractor to the screen or get Kerbal Engineer/VOID if you want to check your angles. =D

[Jupiter3927]

Math only makes it less of a guessing game if you know how to do the math.
I actually have a few calculator programs written to make the calculation bits faster.

[Pisces]

Originally posted by ray.mcdonough:

Alright,

I get the 'Interactive illustrated interplanetary guide and calculator for KSP' and I know how to get the angles. I've been able to eye-ball Duna intercepts.

You see, I got gun-shy when my three-hundred hour career glitched permanently, and I suspected mod conflicts. It was mostly my fault, because I had deleted all my saves, but still, I decided to see If I couldn't do everything vanilla.

My question is; is there any way outside of just eyeballing it to check the numbers on the phase and ejection angles?

Simply install kerbal alarm mod. Set a alarm. Choose the target and orgin bodies. It will calculate the angle for you automatically and it will stop any time warp when you reach the angle. A notification will be popped up.
And this is only one of the functions in this mod.

[ray.mcdonough]

Originally posted by Cato:

Originally posted by ray.mcdonough:

This is all very impressive, guys, but you failed to answer my op question; I didn't ask how to do the math, I have that calculator to do it for me. Sort of like for real.

What I asked was how do you tell the angles are right in the vanilla game, beyond the Mark I eyeball?

Well, Jupe probably answered it.

Oh silly me its shift cos :P (thanks btw)

Ray heres a trick I learned; draw a line from the lower planet to the upper planet (so from Kerbin to Duna) if it is possible to draw a straight line from Kerbin to Duna that is parallel to the sun - then the transfer window exists

No kidding? I'll have to try that