Orbit related questions 1.0

[Veldez]

A couple questions:

1. I was definitely in the "throw moar rockets at it if you fail to reach orbit" crowd for 0.9, and while it was fun, it doesn't seem to really work in 1.0. I have yet to get anything into orbit yet. Is it really important to stay below terminal velocity now for efficiency? I turned my SRB down to 70% but still break 200 m/s well before 5000m up. As a related question, is there a list of terminal velocities by altitude and planet anywhere?

2. Is there a way to see the temperature of various parts in stock KSB? My rockets are regularly glowing, and occasionally exploding from heat. It would be handy to see where the heat is.

3. I had thought that an engineering report including Dv and TWR was going to be part of the update, but I cannot find it. Is it buried somewhere I just haven't looked, or are all the Dv and TWR figures people are quoting coming from a mod, or heaven forbid, MATHS!?

Edited April 30, 2015 by Veldez

[KatzOhki]

My problem with ascent was the gravity turn. Look into what other people are saying (start early and do it gradual) and see if that helps.

There is a debug heat overlay I think.

I think it's been delayed.

[Deutherius]

I haven't clocked nearly enough hours into 1.0 (or the forum) to be 100 % sure, so take it with a grain of salt.

1. I was definitely in the "throw moar rockets at it if you fail to reach orbit" crowd for 0.9, and while it was fun, it doesn't seem to really work in 1.0. I have yet to get anything into orbit yet. Is it really important to stay below terminal velocity now for efficiency? I turned my SRB down to 70% but still break 200 m/s well before 5000m up. As a related question, is there a list of terminal velocities by altitude and planet anywhere?

Terminal velocity is now governed by the shape of your craft, so there probably won't be any precise lists. If you build your rocket tall instead of wide, and put nosecones on everything, you can forget about terminal velocity altogether - it's the heat that will cause you problems way before you notice any atmospheric losses. So unless it's glowing red hot and exploding, feel free to go faster.

You didn't tell us what exactly is causing you to not reach orbit, so I cannot help you until you do.

2. Is there a way to see the temperature of various parts in stock KSB? My rockets are regularly glowing, and occasionally exploding from heat. It would be handy to see where the heat is.

Alt+F12, physics, thermal, display thermal data in action menus, right click on parts.

3. I had thought that an engineering report including Dv and TWR was going to be part of the update, but I cannot find it. Is it buried somewhere I just haven't looked, or are all the Dv and TWR figures people are quoting coming from a mod, or heaven forbid, MATHS!?

Not part of this update. Dunno about the origin of folk's figures, it might be either of those (depending on free time and sanity), but Mechjeb and KER should be updated and working already, so it's probably mods.

[Superfluous J]

I've had a lot of luck with this method:

Turn 5 degrees in the first 500 meters.

Starting at 2000 meters, every 1000 meters turn another 5 degrees (So at 2000m turn to 80 degrees. 3000m 75 degrees). Every even amount, you should be on a degree tick divisible by ten), until you get to 45 degrees at 9000 meters.

At this point, switch to map mode (or better use KER) to find your apoapsis. Hold 45 degrees until your apoapsis is at 20km, then go down to 40. Hold there until your apoapsis is at 30km, go to 30. 40km apoapsis goes to 20, and at 50 crank it to the horizon.

If during this ascent your prograde marker falls very far down from where you're pointing, add boosters. If it's very far above you, remove boosters (or at least throttle down).

[maceemiller]

Ahh! This must be where im going wrong in 1.0. Ive been trying to fly the old way (straight up to 10000 then turn sharp to 45 degrees) and all that's happening is my craft starts spinning out of control.

- - - Updated - - -

Ahh! This must be where im going wrong in 1.0. Ive been trying to fly the old way (straight up to 10000 then turn sharp to 45 degrees) and all that's happening is my craft starts spinning out of control.

[Veldez]

Ok, maybe that is my issue with orbiting as well. I have been doing little if any turning before 10,000m. Basically straight up until 10-12km, then turn to 45 degrees as fast as I can. Haven't spun out of control, but I have not orbited either. Once my apo hits 75km or so, I kill engines (or usually drop SRB's lol), coast to near apo, and full throttle toward horizon. I always run out of fuel before circularizing, the closest I have gotten is a decaying orbit half in and half out of atmosphere. Will try turning slowly and as soon as possible.

[Veldez]

Ok, I got two launches to orbit now, by nosing over slowly as soon as I hit a couple hundred meters altitude. Kinda of a pain, having to swap between map view to watch apo, and the flight view to pop stages, but it works. So, it seems the old way of getting into orbit doesn't work anymore. Also thanks for the alt-F12 heat thing, and too bad about the flight engineer data..... I was REALLY wanting that. I don't want to use any mods.

[cybersol]

In most games I also don't like to install mods, especially at first, but I also like numbers and precision. Kerbal Engineer, Kerbal Alarm Clock, and Precise Node provide that information and precision to KSP without affecting the stock gameplay in any other way. I consider them the GUI the devs would make if they played the game like the geek that I am. For example, since precise node hasn't been fully updated for 1.0, I just spent 5 minutes tweaking my manuever node to change aerobraking periapsis by 3 km, when I could have done the same thing with precise node in 5 seconds.

EDIT:

Kinda of a pain, having to swap between map view to watch apo...

For example, KER puts a HUD with your that Apo height right next to your altimeter. Edited April 30, 2015 by cybersol

[EtherDragon]

A couple questions:

1. I was definitely in the "throw moar rockets at it if you fail to reach orbit" crowd for 0.9, and while it was fun, it doesn't seem to really work in 1.0. I have yet to get anything into orbit yet. Is it really important to stay below terminal velocity now for efficiency? I turned my SRB down to 70% but still break 200 m/s well before 5000m up. As a related question, is there a list of terminal velocities by altitude and planet anywhere?

It is not as critical to watch out for terminal velocity. What has become more cumbersome is torque in the nose of a rocket from induced drag - particularly when the rocket is not headed directly into the air-stream. Without tail-fins this torque is strong enough to overwhelm any control input flipping your rocket over. Also note, the torque increases with air-flow (i.e. velocity). If you don't have tail-fins keep your nose pointed into the wind!

2. Is there a way to see the temperature of various parts in stock KSB? My rockets are regularly glowing, and occasionally exploding from heat. It would be handy to see where the heat is.

ALT-F12 brings up the debug menu, which enables options to see the heat.

3. I had thought that an engineering report including Dv and TWR was going to be part of the update, but I cannot find it. Is it buried somewhere I just haven't looked, or are all the Dv and TWR figures people are quoting coming from a mod, or heaven forbid, MATHS!?

It was going to be, but they ran out of time and released without it. It may still appear in a future update.

[MisterFister]

Is it really important to stay below terminal velocity now for efficiency? I turned my SRB down to 70% but still break 200 m/s well before 5000m up.

Terminal velocity is now governed by the shape of your craft, so there probably won't be any precise lists.

Each of you is simultaneously almost-right and frustratingly wrong at the same time.

Terminal velocity is always a problem, and always was. Since terminal velocity is a component of atmospheric drag, and NuStock aerodynamics have changed, what terminal velocity is has changed, but it's no less important. Simply, the nature of that change makes it less of a practical concern for most early-tech launches.

Terminal velocity, in any aerodynamics, is simply where acceleration force going forward is cancelled by drag forces working in opposition. Skydivers have this very simple, since their "accelerating force" is always gravity (1G) and always in a straight line toward the hard deck. As they initially jump and enter freefall, wind resistance is negligible in comparison to their body weight, and as such, their downward velocity increases steadily along a linear progression of ~9.8 meters per second in downward velocity for every second spent in freefall -- abbreviated as meters per second squared, or m/(s^2). (Their cumulative vertical distance travelled is an exponential affair, since speed is constantly changing, but that's outside the scope of the question here.)

If they were in a vacuum, they'd literally continue accelerating at the same rate literally forever until something changed that -- most likely, impact with the hard deck. (It should be noted that if they began freefall in a vacuum from "really far away," for example the altitude of the moon, their initial numbers would be different, since gravity decreases the farther out you go, so it would initially be less than 9.8m/(s^2), and gravity from other bodies would affect things, but for our simplified purposes here, the underlying truth remains valid: at time of impact, a skydiver would theoretically be travelling at many hundreds of thousands of miles per hour, likely appreciable fractions of the speed of light by that point. Impact energies of a human-sized impact like that would in all probability be the equivalent of a small to medium sized nuclear bomb going off.)

Now, that digression seems absurd, and totally is absurd, for the simple reason that people don't skydive in a vacuum -- they do it in the atmosphere. Now, just sitting there at your computer reading this, air is flowing over you, either from the breeze through an open window, maybe you have a small fan on your desk at work, or even microscopic air currents from people in the next room a-la the butterfly effect. All of those air currents across the surface of your clothing and across your skin imparts a very real, very measurable, amount of force -- usually in such tiny strengths that we simply don't notice them. At sea level pressure (which we'll call "100%" for the time being) air has a specific consistency, a specific viscosity or "goopiness coefficient." In other words, it's a lot heavier and harder to push around than pure helium would be, but a lot less substantial than molasses. This becomes important when masses start moving around at higher velocities.

It doesn't matter if the mass is moving or stationary, or if the air is moving or stationary -- it just matters that there should be relative motion between them. For example, getting strapped into a harness inside a wind tunnel, where you are stationary but large fans blow hurricane force winds, causes a lot of air turbulence on the human form. The same thing might happen on movie sets simulating dangerous thunderstorms. This principle is harnessed on aircraft carriers, too -- standard flight operations dictate that the flight deck be steered into the wind whenever possible, so that whatever ambient wind speed there is will only make aircraft flying easier, even if only by a margin of however many knots the windspeed might be that day, so that heading into a 15 knot headwind at a ship speed of 15 knots yields a flightdeck headwind of 30 knots -- this means that an aircraft with a stall speed of 70 knots only has to worry about that 40 knot difference when taking off or landing into that headwind that's been artificially inflated up to 30 knots. Aircraft can then land at higher throttle settings, an important safety consideration if the plane misses the deck and needs to accelerate and climb for a go-around and another attempt, and it's easier to hit that flightdeck at a relative approach speed of 40 knots than it would be to do so at 70 knots.

Back to the skydivers, though. Ignoring the original flight speed of the aircraft they jump from, since the planes tend to slow down just before a jump happens anyway, the initial "air speed" relative to the skydiver after a few seconds in freefall gets pretty fast rather quickly -- generally, five seconds in, the airspeed is around 50m/s, which equates to 180kph or 112mph -- a healthy gale, trending toward strong tropical storm-force windspeeds. Anyone who's flown a kite, anyone who's stuck their hand out a car window while driving on a highway, anyone who's seen what happens when a bird flies headlong into a window, knows that those kinds if airspeeds can become rather undeniable. In our skydiving case, they actually start to cancel out the accelerating effect of gravity -- the rate of acceleration slows down, and overall vertical speed levels out. Eventually, an equilibrium will form, and the skydiver will just drop at a constant rate, with no significant speed fluctuations or increases; acceleration will terminate, hence the term, terminal velocity. Most skydivers spend MOST of their time around these speeds, generally. A trained professional can go into an intentional nosedive (unrecommended outside of emergency situations to catch up with someone ahead who needs help) and achieve speeds in excess of 115m/s downward travel, but the massive tradeoff for such a maneuver is that it consumes altitude very quickly.

Rocket science introduces some extra variables, but the physics remain unchanged. Now, instead of ONE direction (downward) with ONE constant force (gravity) you have all sorts of directions (with vectored thrust and control surfaces) and all sorts of accelerational possibilities (different engine configurations, the ability to change engine throttle settings, different types of fuel problems which would DECREASE thrust, on top of always-present gravity itself) and also the simple fact that you're playing in a wider range of atmospheric possibilities. Generally, skydiving happens within the bottom-most 3,000 meters of altitude or thereabouts. Much higher and you start requiring special equipment to be able to breathe, to say nothing of the potentially dangerous low temperatures at those altitudes, wind shear, and other factors that make non-military skydiving at higher altitudes generally impractical. While it's true that the air density and air resistance values at 3000 meters up is measurably different at sea level, the changes are surprisingly small in the grand scheme, and in any even, the skydiver is VERY quickly returning to sea level conditions as they fall anyway.

With rockets, you have to worry about things like the jet stream, global air currents, and the fact that not only does air density decrease rapidly as you go up (which affects air resistance and therefore terminal velocity calculations) but that the atmosphere is really divided into measurably distinct LAYERS, kind of like layers of oil and water in an unshaken bottle of salad dressing. Where those layers have a meeting between boundaries can have some pretty intriguing physics regimes, which can sometimes factor into flight planning. (Indeed, the space race took almost two decades of people working very hard to figure out all of these considerations before we could reliably call our shot and send humans to orbit and back again, whereas here in KSP we can do so in career mode sometimes in as few as 4 launches across less than a day of in-game elapsed time.)

That's all interesting, bruh, but what's your point?

My point is this: terminal velocity is a LOT higher (and therefore much more difficult to attain with early-career tech levels) in NuStock than it was in oldStock. And really, this was the primary complaint about oldStock aerodynamic modeling anyway -- it more accurately modeled flying through some sort of digital mayonnaise than it could ever have modeled air resistance. Think about it -- how fast can you "run" through water at the beach, without lifting your legs completely out of the water with each step? Now, imagine that same practice, but instead of running through water, run through mayonnaise. You'd go a lot slower -- because your terminal velocity would be a lot slower.

Terminal velocity also depends on shapes, yes. This is why a skydiver can still fire a rifle downward without the bullet coming back to hit the shooter, because the streamlined bullet has much less air resistance, and therefore a much HIGHER terminal velocity, than the diver that fired it. Wingsuits, on the other hand, allow a diver to intentionally increase one's air resistance, thereby reducing terminal velocity, allowing one to bodyglide and steer. Streamlined phallic-shaped objects can cut through wind resistance more effectively, such as arrows, missiles, and vertical rocket stacks. But the underlying physics remain the same.

oldStock aero allowed us something redonkulous, like ~150m/s or something, in sea level terminal velocity for the average vertical stack rocket (calculated strictly on mass, not on shape). nuStock on the other hand models closer to ~380m/s terminal velocity at sea level for the average vertical stack, which no average rocket would ever attain or bump up against, because by the time you're going that fast, you're high enough so that atmospheric density has dropped, and THEN your new tV is >600m/s.

As long as you remain prograde, terminal velocity will never be a significant issue in nuStock aerodynamics during a normal career-mode ascent program. Sometimes to do things you NEED to divert from prograde, but then it's not really fair to call it "lateral tV" or "collateral vector coefficients," it's just "drag."

Fly safe!

/lesson

[Drethon]

I haven't done extensive testing yet but I got to orbit with a fairly small craft using my FAR approach of follow the prograde. I fly to the edge of prograde in the direction I want to turn and hold it there while prograde shifts. This keeps the nose from being too far from the flight path. I think I turn too slow at first and too fast at higher altitudes but it works fairly well.