My personal breakthrough Eureka moment I did by mistake.

[User Unrelated]

I've had that orbit capture thing happen on Gilly before

it didn't actually pull me into a STABLE orbit, but it was VERY close, and the game was just rounding up to display the next (yellow) orbit path.

[merendel]

Not sure with Ferram that is essentially a golden rule with the friction and drag aspect, the small SRBs are light, aerodynamic, and give a very sweet punch in speed. Nothing gets me from 400m/s to 2k m/s with so little weight, in so short a time, and so efficiently. You gotta also remember the cost, it's actually less than what I'd need otherwise.

you can make a liquid booster aerodynamic with ferram, just stick a nosecone on the top tanks. And if anything ferram gives another reason for that golden rule to stand. If you overload the TWR with solid boosters you have no choice but to ride it out even if you start going too fast to be stable, liquids you can chop throttle. They are a perfect echonomical solution for adding to a rocket with a TWR of around 1 to get it up near 2 and off the launchpad and I fully support their use in that role. If your point had been adding them to your first stage is a good idea then I'd be in full agreement.

However most of what you'd seemd to be excited about was adding them to a mid/upper stage and correct me if I'm wrong even used some in space? By the time your in the upper atmosphere ferram starts playing much less of a role (and yes, ferram is in my modlist). yes it can still hammer you if your doing something stupid but there will not be much of a difference between a pair of liquid boosters with nosecones verses a cluster of those micro SRB's aerodynamicly once your high up. Once your actualy in space your still back to the golden rule regardless and the sooner you burn off the lower ISP thrusters the better.

Incidentaly if you disregard FAR you'd get more bang for your buck with a stock RT-10 solid. A single RT10 is ~ equivelent to 3 globe 1s with their thrust diled down to 68%. similar total thrust, burntime, and dV. a cluster of 3 globes however is 150 more expensive and is .2ton heavier in dry weight. extra mass is always costly to carry along. Then agian at this point I wouldnt even bother counting the kerbucks value of the parts, particularly compairing stock to modded. You do realize that several of the KW engiens and tanks have identical costs dispite being wildly different sizes? The globe V VI X and X-2 solid rockets are all 800 cost, same as the big stock booster dispite most of them being significantly bigger and more powerful than the stock one.

I will give you that that much thrust in that light a package is difficult to acomplish without spaming some of the really good TWR little engiens but that would always be more expensive to do. However once your up near orbital speed a high TWR is not needed for anything but your own sanity during burns. a higher TWR gets you shorter burns but how far away a target you can reach comes down to your ISP and the amount of fuel you have. Theres a reason most people make longrange ships whos main engien is an LVN or a cluster of such and not a bunch of solid boosters. at 800 ISP you'd get far more range for a similar weight than you would off the 250 ISP solid booster.

[LadyAthena]

you can make a liquid booster aerodynamic with ferram, just stick a nosecone on the top tanks. And if anything ferram gives another reason for that golden rule to stand. If you overload the TWR with solid boosters you have no choice but to ride it out even if you start going too fast to be stable, liquids you can chop throttle. They are a perfect echonomical solution for adding to a rocket with a TWR of around 1 to get it up near 2 and off the launchpad and I fully support their use in that role. If your point had been adding them to your first stage is a good idea then I'd be in full agreement.

However most of what you'd seemd to be excited about was adding them to a mid/upper stage and correct me if I'm wrong even used some in space? By the time your in the upper atmosphere ferram starts playing much less of a role (and yes, ferram is in my modlist). yes it can still hammer you if your doing something stupid but there will not be much of a difference between a pair of liquid boosters with nosecones verses a cluster of those micro SRB's aerodynamicly once your high up. Once your actualy in space your still back to the golden rule regardless and the sooner you burn off the lower ISP thrusters the better.

Incidentaly if you disregard FAR you'd get more bang for your buck with a stock RT-10 solid. A single RT10 is ~ equivelent to 3 globe 1s with their thrust diled down to 68%. similar total thrust, burntime, and dV. a cluster of 3 globes however is 150 more expensive and is .2ton heavier in dry weight. extra mass is always costly to carry along. Then agian at this point I wouldnt even bother counting the kerbucks value of the parts, particularly compairing stock to modded. You do realize that several of the KW engiens and tanks have identical costs dispite being wildly different sizes? The globe V VI X and X-2 solid rockets are all 800 cost, same as the big stock booster dispite most of them being significantly bigger and more powerful than the stock one.

I will give you that that much thrust in that light a package is difficult to acomplish without spaming some of the really good TWR little engiens but that would always be more expensive to do. However once your up near orbital speed a high TWR is not needed for anything but your own sanity during burns. a higher TWR gets you shorter burns but how far away a target you can reach comes down to your ISP and the amount of fuel you have. Theres a reason most people make longrange ships whos main engien is an LVN or a cluster of such and not a bunch of solid boosters. at 800 ISP you'd get far more range for a similar weight than you would off the 250 ISP solid booster.

I was talking about the ride up, not in space when the rockets are actually burning. They still create drag while being dead weight, and with them being smaller, lighter, and more aerodynamic, cheaper, but still the same thrust... it's a win win win win situation.

Even though cost doesn't matter "yet" like someone pointed out, why not start planning for it?

[palioxis1248]

Is it really? logically if you believe in the "big bang" theory then the reason the planets revolve around the suns is the same exact reason why I was captured in the Mun orbit without the use of fuel. It's just the speed I was moving was at just the right speed when hitting the Mun gravitational pull that it pulled me into an orbit. It's essentially the same exact reason of why planets were captured in the suns gravity well without the use of fuel.

There are some important differences here. The planets formed around the Sun. They weren't speeding into the solar system above solar escape velocity like your lander was zipping towards the Mun at above Munar escape velocity. Furthermore, even for captured moons such as those surrounding various gas giants and Mars, those either received some sort of gravitational nudge while in the parent body's SOI by another body that caused them to lose momentum and enter orbit, or were slowed down by tidal interactions with the planet. Since KSP doesn't model tidal forces and there are no other massive bodies in the Mun's SOI, it can only be that some glitch in the physics calculations (not uncommon, especially if your trajectory was already almost a capture) caused you to settle into an orbit.

So yes, your fuel-free capture orbit was not that extraordinary, but not for the reasons you listed.

[LadyAthena]

There are some important differences here. The planets formed around the Sun. They weren't speeding into the solar system above solar escape velocity like your lander was zipping towards the Mun at above Munar escape velocity. Furthermore, even for captured moons such as those surrounding various gas giants and Mars, those either received some sort of gravitational nudge while in the parent body's SOI by another body that caused them to lose momentum and enter orbit, or were slowed down by tidal interactions with the planet. Since KSP doesn't model tidal forces and there are no other massive bodies in the Mun's SOI, it can only be that some glitch in the physics calculations (not uncommon, especially if your trajectory was already almost a capture) caused you to settle into an orbit.

So yes, your fuel-free capture orbit was not that extraordinary, but not for the reasons you listed.

That all too me still doesn't make complete sense...

The laws of physics state, that the reason a body orbits another like a spacecraft, is because of the balance between its velocity and the power of the gravity on its pull. If you are traveling at the right angle, at the right speed, and hit the gravitational pull, I don't see why you can't duplicate the same thing. Its essentially the same exact thing... just minus an extra burn because you're already traveling at that speed required to enter the orbit...

so I'm not really following exactly why this can't be the case, or why the laws of physics seems to change its rules now that you're no longer firing an engine, or what not.

Can you try to explain it a bit more?

Edited March 15, 2014 by LadyAthena

[Red Iron Crown]

I don't find SRBs to be a good solution for anything other than separating stages, and they're particularly poor once in orbit. The same mass of liquid fuel will be better in almost every way.

Comparing cost when the parts pricing hasn't been finalized, plus some parts are from a mod, is a bit nonsensical. I mean, it's good to start thinking about cost given that economics are coming soon, but I don't think cost effectiveness can really be compared with any sort of authority yet.

[costermonger]

The laws of physics state, that the reason a body orbits another like a spacecraft, is because of the balance between its velocity and the power of the gravity on its pull. If you are traveling at the right angle, at the right speed, and hit the gravitational pull, I don't see why you can't duplicate the same thing. Its essentially the same exact thing... just minus an extra burn because you're already traveling at that speed required to enter the orbit...

Yes, but you can't do those things and also actually get there in a Hohmann transfer. KSP's version of physics requires us to exceed the escape velocity of a body in order to get an orbital transfer to said body's SOI, and we enter the SOI on a hyperbolic orbit every time. To turn it into an parabolic or circular orbit, we need to expend dV to get below escape velocity. IF you hit the SOI right at it's outer limit at a speed just above escape velocity, you can create a circular orbit for very little dV expenditure. I think you were probably doing this and KSP made a rounding error.

In the real world, SOI isn't a thing and the dV 'nudge' needed to turn a hyperbolic orbit into a parabolic or circular (ie, captured orbit) can be provided by another planet or moon. KSP doesn't render this at all.

[LadyAthena]

Yes, but you can't do those things and also actually get there in a Hohmann transfer. KSP's version of physics requires us to exceed the escape velocity of a body in order to get an orbital transfer to said body's SOI, and we enter the SOI on a hyperbolic orbit every time. To turn it into an parabolic or circular orbit, we need to expend dV to get below escape velocity. IF you hit the SOI right at it's outer limit at a speed just above escape velocity, you can create a circular orbit for very little dV expenditure. I think you were probably doing this and KSP made a rounding error.

In the real world, SOI isn't a thing and the dV 'nudge' needed to turn a hyperbolic orbit into a parabolic or circular (ie, captured orbit) can be provided by another planet or moon. KSP doesn't render this at all.

Still not entirely understanding it... the variable of gravity is still missing, but I'll take your word for it, since science in the rocket science/astronomical area isn't exactly the greatest.

[ThinkOutsideTheHangar]

So you managed to do something like aerobraking around the Mun? Amazing!

[Geschosskopf]

Yes, but you can't do those things and also actually get there in a Hohmann transfer. KSP's version of physics requires us to exceed the escape velocity of a body in order to get an orbital transfer to said body's SOI, and we enter the SOI on a hyperbolic orbit every time. To turn it into an parabolic or circular orbit, we need to expend dV to get below escape velocity. IF you hit the SOI right at it's outer limit at a speed just above escape velocity, you can create a circular orbit for very little dV expenditure. I think you were probably doing this and KSP made a rounding error.

I've had a number of occasions where the map view has shown me falling straight into orbit upon arrival but these have never worked out in actual practice. It has always been as you say, where I approach the moon at a very low relative velocity from an orbit around the central body that's nearly as far out as the moon is. Such as, aerocapture at Duna into an orbit out nearly as far as Ike, then going on to Ike after waiting for a phase angle like with an interplanetary transfer. It also happens at Jool if I park between 2 moons and later move to 1 or the other.

The map shows the "free" orbit at the target moon as I'm creating the node to burn to it, while my ship is still a fair distance away, like half an orbit around the central planet. I've come to view this as a big warning sign that I'm entering Kraken-infested waters. Every time I've tried to let this play out, what happens instead is that my ship coasts toward the projected encounter but about halfway there, suddenly it finds itself in the moon's SOI, at low alittude and high speed, heading for an impact, with insufficient room to save it. So nowadays, whenever I see the "free" orbit on the map, I tweak the maneuver node some more until it goes away

[palioxis1248]

That all too me still doesn't make complete sense...

The laws of physics state, that the reason a body orbits another like a spacecraft, is because of the balance between its velocity and the power of the gravity on its pull. If you are traveling at the right angle, at the right speed, and hit the gravitational pull, I don't see why you can't duplicate the same thing. Its essentially the same exact thing... just minus an extra burn because you're already traveling at that speed required to enter the orbit...

so I'm not really following exactly why this can't be the case, or why the laws of physics seems to change its rules now that you're no longer firing an engine, or what not.

Can you try to explain it a bit more?

Well the thing is, you are not travelling at the right angle, at the right speed and at the right place when you enter the Moon's SOI. With Keplerian orbital mechanics, if you are travelling at escape velocity when you enter an object's SOI (which you pretty much have to be), you will be at escape velocity for every point in your orbit. So there has to be some change in your current velocity in order for you to get capture. This change in velocity can happen when you fire your engines, or you only needed a few m/s to enter orbit, and the system glitched to change your ship's velocity by those few m/s. Hope this clears things up.

[LadyAthena]

Well the thing is, you are not travelling at the right angle, at the right speed and at the right place when you enter the Moon's SOI. With Keplerian orbital mechanics, if you are travelling at escape velocity when you enter an object's SOI (which you pretty much have to be), you will be at escape velocity for every point in your orbit. So there has to be some change in your current velocity in order for you to get capture. This change in velocity can happen when you fire your engines, or you only needed a few m/s to enter orbit, and the system glitched to change your ship's velocity by those few m/s. Hope this clears things up.

I think it does. Thank you.