2. Space Flight School: Basic Lessons
So, ready for your first lesson? Let’s go then!
2.1. Taking control of a spaceship for the first time
Right now, you are in reality sitting comfortably on a simulator chair. But on the simulator world, you are a floating consciousness free to visit any place on the universe. That’s cool and all, but that’s not why you’re here. You’re here to learn how to fly a spaceship! So let’s summon one for you!
- Make sure you’re on a comfortable location, close to Earth. If you’re not, please go there! [‘Shift+h’ 3 times to select Earth, ‘g’ 2 times to go there fast.]
- Click on the Spacecraft Manager icon and then on Build. Select SpaceEngine > CloseSpace Corp > Skylone. Then, click on “Take Control”. As mentioned, you don’t have to use this ship, but it’s recommended you do.
Fig. 2.1: Building a Ship.
- Whoa! That’s a lot of controls and indicators! It is overwhelming, yes. But you’re in control now, so try moving around a bit to feel the machine you’re in! We’ll study the controls on the next lesson, but for now, here are some simple ones:
[w, a, s, d, r, f: accelerate forward, left, backward, right, upward, downward]
[q, e, num4, num6, num2, num8: rotate counterclockwise, clockwise, left, right, down, up]
[Mouse wheel: increase/decrease main engines acceleration]
See how all indicators on your HUD change when you accelerate? Yeah, that’s a lot of information there, and to be a good pilot you have to understand every single one of them!
2.2. Familiarizing yourself with the ship controls and HUD
This will be a bit boring, but trust me, it’s probably the most important section of this guide! So take your time here, do not rush past this point or just skim through it!
So, this is what the HUD looks like immediately after you take control of the ship:
Fig. 2.2: HUD immediately after taking control of a ship, on Orbit mode.
That´s a little too much to study at once, don’t you think? Let’s clear it up a little: Turn the HUD off for now. [Ctrl+1]. This is what you should have now:
Fig. 2.3: HUD turned off. (a) is the ship control bar, (b) is the selected object info.
Phew, a lot better, right? First of all, the control bar (a) is the one we will focus on [on the image, it’s covering the bar below, but don’t worry, those controls are not used when flying a ship]. The selected object info (b) contains a lot of useful information on the currently selected object, the ship in this case. We will focus on some of the info there at a later point. So now, stop the simulation time using the pause/resume button on the Time Control bar (c) and let’s go over each of the controls in detail!
That’s all for the main controls! The most basic keys for moving your ship were mentioned before, so now here’s a list of all of them, for reference:
Ctrl F3 ------------------------ toggle spacecrafts manager
"Rename" button --------------- rename spacecraft
"Build" button ---------------- toggle list of spacecrafts to build
"Destroy" button -------------- remove spacecraft from the fleet
"Take control" button, 4 ------- take control on selected spacecraft
"Fly here" button -------------- order spacecraft to fly to the current location
"Warp here" button ------------- order spacecraft to warp to the current location
Ctrl 1 ------------------------- toggle off HUD
Ctrl 2 ------------------------- switch HUD in the atmospheric mode
Ctrl 3 ------------------------- switch HUD in the orbital mode
Ctrl 4 ------------------------- switch HUD in the warp mode
Ctrl 5 ------------------------- switch HUD in the docking mode
4 ------------------------------ take control of last/selected spacecraft
5 ------------------------------ rotate "prograde"
6 ------------------------------ rotate "retrograde"
7 ------------------------------ rotate "radial"
8 ------------------------------ rotate "antiradial"
9 ------------------------------ rotate "normal up"
0 ------------------------------ rotate "normal down"
End ---------------------------- rotate horizontally
Left drag ---------------------- turn the current spacecraft
Right drag --------------------- rotate the camera around current spacecraft
Middle drag -------------------- look around
Mouse Wheel -------------------- change main engines thrust (if available)
Shift + Mouse Wheel ------------ change retro engines thrust (if available)
Ctrl + Mouse Wheel ------------ change hover engines thrust (if available)
Alt + Mouse Wheel ------------ change warp drive power (if available)
W, Up --------- accelerate forward (thrusters)
S, Down ------- accelerate back (thrusters)
A, Left ------- accelerate left (thrusters)
D, Right ------ accelerate right (thrusters)
R, NUM1 ------- accelerate up (thrusters)
F, NUM0 ------- accelerate down (thrusters)
Q, NUM7 ------- turn counter clockwise (thrusters or ailerons)
E, NUM9 ------- turn clockwise (thrusters or ailerons)
NUM8 ---------- turn up (thrusters or elevator)
NUM2 ---------- turn down (thrusters or elevator)
NUM4 ---------- turn left (thrusters or rudder)
NUM6 ---------- turn right (thrusters or rudder)
NUM5, X ------- stop rotation (kill rot autopilot)
Ctrl NUM8 ----- look up
Ctrl NUM2 ----- look down
Ctrl NUM4 ----- look left
Ctrl NUM6 ----- look right
Ctrl NUM5 ----- look back
Z ------------- shutdown engines
Alt Z ------- shutdown warp drive
Shift Z ------- toggle syncvel autopilot
C ------------- rotate spacecraft to the selected object
G ------------- auto fly/warp to the selected object
Shift G ------- auto fly to the selected object (using main engines)
Alt G ------- auto warp to the selected object
H ------------- toggle hold altitude autopilot (if available)
U ------------- toggle flight assist (auto syncvel with thrusters)
O ------------- toggle view of spacecraft's trajectory and planets orbits
Alt O --------- zoom out to see spacecraft's trajectory
Alt C --------- center camera on a spacecraft
T ------------- choose target object
P ------------- choose reference body
A lot of buttons and keys, right? Don’t worry, you’ll get used to them in no time! And you don’t have to know all of them in your head, only the most used ones. Also, it doesn’t hurt to leave a copy of the previous pages next to you at all times!
Now, let’s move on to the HUD modes. We’ll go through them on a different order than the buttons, so pay attention to their names! We’ll begin with the elements common to all modes:
Common HUD Elements
There are elements that are common to all HUD modes. To make it easier to identify them, switch to the Docking HUD mode (Ctrl+5), and you will see something like this:
Fig. 2.4: Elements common to all HUD modes.
- Reference body indicator: This simply shows the name of the reference body used, if any.
- Target indicator: Name of the object set as the ship’s target.
- The circle with the dot at its center is the velocity indicator. Not only this shows where you are going, but also the the velocity relative to a reference body and its name. Remember: in space, you’re not always going in the direction your ship is facing, even at full throttle! That’s why this circle is so useful! It’s possible that more than one of these are present. This happens when your target is different than your main reference body shown in (a). There is also the opposite of this circle, with an ‘X’ inside. It’s the same thing, but shows the direction you are moving away from, with the same velocity value, but negative.
- The W shaped icon shows your ship’s facing. It can match (c), but it usually won’t. Additionally, since you’ll be rotating your view a lot, and many ships doesn’t have an easily identifiable front, you’ll be searching for this icon all the time, trust me!
- Coordinates indicator: These coordinates are relative to your reference body, so it only shows up if there is one.
- g-Force: The force the ship is submitted to when accelerating. If all of your engines and thrusters are off, this will be equal to the gravity. Fun fact: Back in the day, when space travels were at an very early stage, pilots (called astronauts) would sense the same g force the ship would, and it wasn’t uncommon that people would pass out when subject to forces close to 10 gs, that is, 10 times Earth’s gravity. Today we have inertial dampeners, so passing out is a thing of the past, and we can easily achieve accelerations up to 100 gs without turning into pancakes.
These elements are very important, so remember what they indicate, you’ll be using the information provided by them all the time!
Docking HUD (Ctrl+5)
The docking HUD is the most simple of all. It basically only contains information about your target and your distance/relative velocity to it. You’ll be using this a lot when docking ships, obviously, but it’s also useful when simply approaching any object, due to its simplicity:
Fig. 2.5: The Docking HUD Mode.
- Docking Ports: When you select the Docking HUD mode, this window may appear. It shows the docking ports of the selected ship, and whether they are free. When docking, you simply click one of the available docks to initiate the process. (More on this on the Docking lesson.)
- Docking info. Pretty self-explanatory. Just a note: The angle with dock is a sum of all the angle differences, so you have to rotate in all directions to reach 0.
- Target ship: This indicates where the ship you want to dock with is at, and its name.
- Trajectory relative to the target ship.
- Trajectory relative to the reference body.
Notice how we now have two circles! One showing the relative velocity with Earth, and the other with the target ship!
Horizon HUD (Ctrl+2)
The Horizon HUD introduces two very important elements, and is useful when descending into a planet or moon (or star, I won’t judge you), and when flying close to the surface:
Fig. 2.6: The Horizon HUD Mode.
- Heading indicator. The downwards arrow points to the heading angle. 0º or 360º represents north, 90º east, 180º south, and 270º west. Even when on other planets, we still maintain this notion of directions. Not all planets may have a very well defined magnetic north like Earth does, so the ship systems automatically choose a “north”.
- Attitude/Inclination indicator: This shows the ship’s inclination, or Attitude, relative to the ground. 0º is straight to the horizon, positive angles are facing upwards, and negative facing the ground. 90º is straight up.
- Height indicators: They indicate your elevation relative to the ground, your altitude (relative to the “sea”, or the lowest terrain on the planet if it’s dry, your vertical speed (VS) and the distance to the center of the object (body radius + altitude).
- Airspeed indicators: These shows the True Airspeed (TAS), or the speed relative to the air, True Surface Speed (TSS), or the speed relative to the ground, and Mach, that is, how many times the speed of sound on that particular atmosphere your velocity is.
- Atmosphere indicators: Mostly self explanatory. The only complicated term here is the dynamic pressure. It is related to the kinetic energy of air particles. You will not usually care much for these values, but remember that flying in different atmospheres is always a different experience (and different altitudes too)! Each atmosphere is unique, and unless you encounter a planet with these values very close to Earth’s, don’t expect to be able to fly easily just because you know how to fly on Earth!
- Atmospheric flight surfaces indicators: Attack and Sideslip angle tells you your angle relative to your velocity. Each one of the other lines represent a surface control and the angle it’s at. Elevators and flaps control the inclination, ailerons the rotation, and rudder controls the “turning”. They only work if the ship’s flight mode is “Aviation”.
This may seem like a lot to digest, but it’ll be clearer on the hands-on lesson!
Orbital HUD (Ctrl+3)
This mode is used when orbiting (entering or leaving as well). We already saw this once, so let’s remember what it was like:
Fig. 2.7: Orbital HUD Mode.
- Same as in Horizon mode, but relative to the trajectory.
- Same as in Horizon mode, but relative to the trajectory.
- The distance to the center of the Reference Body. Not to the surface. To the center. Remember this well, or else you’ll and up crashing a lot of ships (I say that from experience).
- Orbital velocities: V is your current velocity (same as in the circle), V1 is the necessary velocity for a circular orbit based on your distance, and V2 is the escape velocity, or the max velocity the ship can have and still be able to have a stable orbit.
- Orbital parameters. In practice, you’ll only care about whether your orbit is stable or not, which can be easily visualized. But it’s good to study all of those weird letters, so let’s do that!
P: The orbital period, or the time it takes for a full round trip around the body.
a: Semimajor axis, usually it’s the average of the two axis of an elliptical orbit.
e: Eccentricity. 0 means the orbit is a perfect circle, anything higher is an ellipse, and 1 would represent a parabolic trajectory (not a stable orbit).
i: Orbital inclination, measured at the Ascending node (where the orbit starts going above a plane of reference).
Ω: Longitude of Ascending node, it’s basically the angle of the Ascending node in respect of a reference direction.
ω: Argument of periapsis, it’s the angle of the perigee (shortest distance from the body), measured from the ascending node.
M: Mean anomaly. It’s the position of the orbiting body (the ship) along the orbit, at the epoch (which simply is a predefined time).
Tperi: Time to reach the perigee (shortest distance from the body).
Tapo: Time to reach the apogee (highest distance from the body).
Rperi: Perigee length, shortest distance from the body.
Rapo: Apogee length, highest distance from the body.
Rsmin: Minimum distance for a stable orbit. Rperi must be higher than this.
Rsmax: Maximum distance for a stable orbit. Rapo must be shorter than this.
Rperi and Rapo are closely related to, but not exactly equal to the minor and major axis of the orbital ellipse. Not really the point of this guide to explain that in detail, but it’s important to point out!
- The green line shows the ship’s trajectory. If you are on a stable orbit, it’ll be the orbit. In the picture, it’s a straight line to Earth, because the ship’s engines were off the whole time, so the only acceleration is gravity’s.
Again, a lot to take in at once. You can think of this section as a reference to consult if you ever feel the need!
Warp HUD (Ctrl+4)
This mode is the most fun of all, because it usually means you’re going somewhere far away, and fast! Looking through the windows and seeing stars passing by on the distorted space is pretty cool too! It’s not as complicated as the Orbital mode, but may be hard to understand. Let’s take a look at it:
Fig. 2.8: Warp HUD Mode.
- Warp condition: It shows how the warp is going. The physical velocity is your “absolute” velocity. You might be wondering “But absolute? Does something absolute even exist?”. Well, think of it as the velocity in relation to a hyperspace point. In SpaceEngine Simulator, all the galaxies and stars are currently fixed, so in practice, this is the speed relative to any star. The Effective velocity is your travel velocity, considering the warp Boost factor (which is logarithmic). The efficiency is the warp efficiency, you have to face the warp vector to achieve 100%. The rest is self explanatory.
- Warp delta velocity (to your target). This indicator shows the difference in velocity between the warp vector and a desired velocity of 10 km/s in the direction of your target. You have to make it go to zero to have a well aligned warp vector. There is also an opposite indicator, with negative velocity.
- Warp Vector. This shows where you will travel when you engage the warp drive. It is also the same as the Physical Velocity. There is also an opposite indicator, with negative velocity.
- Your velocity in relation to the reference body. When warping close to a planet, it is important to keep an eye on it, because it is possible you end up with a high speed towards it, and then you’ll crash and be disintegrated!
- Your velocity in relation to the target, and an arrow pointing to that target.
- Notice how the Hover engines change to Boost exponent. This is an indicator of the warp drive usage.
At last, that’s all for the controls and HUD elements! Remember to check this section whenever you need! It’s very important that you know the basics of all we studied here, or at least know that they exist, because it’ll make what’s coming next so much easier!
2.3. Spacecraft flying concepts
If you have been paying attention to the selected object info, indicated by (b) in Fig. 2.1, and depending on the time you took to pause time, you may have noticed that the ship’s relative velocity increased. This value is relative to the reference body selected, so it increased because Earth’s gravity is pulling you towards it. This is one of the most important concept to learn: you’re almost always subject to the gravity pull of a celestial object. This is very different from some games that call themselves simulators. SE is meant to be realistic. This means that it’s hard to learn how to pilot a ship, but on the other hand, you’ll leave the simulator as a capable pilot (if you follow all the lessons, of course). So here are some of the concepts you have to learn, and in the process, you’ll probably have to “unlearn” some practices you may have got from lesser games.
Like I said, unless you’re far from any star system, you’ll always have gravity pulling you somewhere. It’s hard to stand still. So keep this in mind when plotting courses, and unless you’re on a stable orbit, be careful and aware of your surroundings!
When plotting a warp course near a planet or star, it’s very likely you’ll end up falling towards it, and you’ll only be able to adjust your course when you’re far away from any massive body. When approaching a planet when warping, the same thing will happen. You can’t have a perfect course, so don’t spend more than a few seconds adjusting the velocity at less than 10 m/s, because it’ll keep changing! Unless you’re in empty space.
(Almost) Everything moves!
On our universe, everything is moving. Every. Thing. If you think you are standing still right now, it’s only because your velocity is the same as Earth’s. And Earth is moving around our sun. And our sun is moving in relation to other stars. And all stars are moving in relation to the center of our galaxy. And our galaxy is moving in relation to every other galaxy. Our universe expanding, so you can picture it as a movement relative to itself. So when going to one celestial body to another, you’ll have to take this movement into account.
In our lifetime, though, we’d (probably) never be able to notice any difference on the distance from one star to any other. From one planet to another, no matter if they’re in the same star system or not, it’s a very different story. The movements are VERY noticeable. That’s why you’ll often arrive at a planet at a relative velocity of ~20 km/s after dropping out of warp speeds.
Picture yourself waking up on a cold and rainy saturday morning, with nothing important to do. Then the phone starts ringing, but it’s out of your reach. What do you do? To ignore it would be your first thought, right? That’s because it takes effort, a lot of it, to change your state from laying down relaxed, to moving. And that’s basically what inertia is. When a body is at a constant velocity (0 is also a constant velocity), it takes effort to change it. This effort is a force, which causes an acceleration depending on the mass of the object. So the more you want to change some object’s velocity, the more energy you’ll have to provide. In spaceflight terms, this translates to more thrust. Remember the physics classes you slept through in high school? They would help you now!
If you played around with the thrusters’ controls of the ship, you may have noticed that the ship doesn’t stop moving when you release the thrust, or turn off the engines completely. This is because of inertia. In our daily experiences, there is friction and drag, forces that are always present, slowing all movements until they stop (relative to Earth, of course!). But in space, there are no such forces (most of the time, anyway). So the ship just keeps on moving, because when you turned the thrust off, there are no other forces present besides gravity to make the ship’s velocity change, and it maintains the same speed it had when you turned the thrusters off.
This is hard to get used at first, and is one of the things that confuses many aspiring pilots! Roughly, if you want to move to the right, for example, you accelerate a bit, wait until you reach the desired position, and then accelerate on the opposite direction, until your velocity reaches 0 again. This must be done all the time! How to decelerate is one of the most important techniques you should develop. I recommend you try it now: Accelerate to 10 km/s in any direction you want, and then decelerate. You’ll see it takes a long time, so you have to always act ahead. This is one of the disadvantages of spaceflight, but on the other hand, space is big and everything is usually far away, so you have time to analyze, think, and plan your movements.
Oh, and as always, these velocities we’re talking about are relative to some other object! Which brings us to…
You probably noticed I’m saying “relative velocity”, “velocity in relation to”, a lot. That’s because all velocities are relative to something! This is also called relativity, but it’s the Galilean Relativity. Take the situation you’re on now: Your ship has a velocity relative to Earth, and Earth has a velocity relative to the Sun. If your ship’s velocity to earth is zero, you’re stopped in relation to Earth, but moving in relation to the Sun. Effectively, your velocity in relation to the Sun is the Earth’s velocity in relation to it, plus your velocity in relation to Earth. It’s not an easy concept, so here’s a small schematic to aid you (or not):
Fig. 2.9: Relative velocities.
If Earth’s velocity in relation to the Sun is 30 km/s, and the ship’s velocity in relation to Earth is 3 km/s, this means that the ship is moving at something close to 31 km/s in relation to the Sun. Notice how the pink arrow is a bit tilted? That’s why the final velocity may not be simply 33 km/h, because the velocity vectors must be summed. This means directions are taken into account.
I could go on and on on this subject, but it’s out of the scope of this guide. Just remember that speeds are relative to something, and directions play a big role on all of it!
Moving on to Einstein’s Relativity, just a quick note: it is partially implemented on the simulator (yes, it’s THAT awesome!), and there are plans to implement it to a greater extent, specially time-dilatation, which means time would pass differently at different parts of the universe, depending on speed and gravity. Even warp effects can cause a big impact on how time is perceived, without reaching an insanely high physical velocity.
Another consequence of relativity would be that it’s impossible to reach the speed of light, because the energy requirements to accelerate something going at a fraction of c increase exponentially the closer it is to c, as the mass also increases. However, we can reach c (but not more than that) with regular thrusters in SE.
Expect to see some of these effects on a future version of the simulator!
The last concept you need to keep in mind is how a ship behaves when there is really a drag or friction force present. Specially when this in turn creates a lift force due to a difference in air pressure at different parts of the ship.
A spacecraft’s thrusters are a big deal. They are strong, and are able to push the ship forward with many g’s. This may cause a massive lift force to be generated if the ship is aerodynamic, and may vary depending on the atmospheric pressure, air density, temperature, gravity, and so on. That’s why many experienced space pilots end up crashing their ship when they’re flying on a planet. It’s very, very different! On atmospheric flight, you have to be gentle with the thrusters, be patient, go slow, and mind your attitude (inclination) and rotation. Usually, the stronger the thrust, the higher the ship will go, and the more downwards your attitude, the faster the ship will go. It’s really hard to adapt quickly to the atmosphere you just entered, so the only tip here is: go slow. Differently than on space, on air the drag and friction forces are present. So, the velocity will not be maintained due to inertia! The thrusters will have to always be on (very weak, but always on), and there will be a preferential orientation, that the ship will always tend to return to.
Only practice will make you understand all of this, so we’ll return to this topic on the specific lessons!
2.4. Entering a Stable Orbit
At this moment, you should still be in your ship relatively close to Earth (~25000 km to its center), with some relative velocity due to gravity and experiments with the controls. If you’re not, please follow the instructions in Section 2.1 to create a ship near Earth and take control of it!
I’ll go through the process of entering a stable orbit and share with you what is happening with my ship. This will be done in simple (but many) steps:
- Check your situation.
If Earth is not set as target or reference, click on the corresponding buttons on the ship control bar, and then click on Earth. Sometimes it may be hard to click on the object you want, or it may be out of sight, so you can select it any other way (F3 is very practical), press F2 to open the Planetary System window, and click there. Here’s what I have:
The first things you have to look at are your distance and relative velocity. If the distance is too short (close to Rsmin) or the velocity too high (anything that would take your ship more than a minute to stop), you have to act fast! Ok, space is big and you have time, but there may be situations where even a few minutes are not enough! In the image above, I accelerated a bit on a random direction to have a considerable velocity. Your numbers may be different and that’s alright, so don’t worry!
You could use your current velocity and reach a stable orbit without coming to a full stop (remember, full stop in relation to Earth!), but that requires experience. So, let’s zero out our relative velocity! Simply click on the Retrograde orientation button and wait a bit until your ship is oriented. When the auto-orientation is finished, accelerate forward and keep an eye on the velocity indicator! How much you accelerate and whether you use the main engines or only the forward thrusters is up to you, it depends on your current velocity and the ship’s capabilities. As a general rule, if the ship is faster than 1 km/s, I use the main engines, if not, the thrusters are usually enough.
Pro tip: When the ship’s velocity is almost zero, or if you accelerated too much and are now going the opposite way you were before, the ship will begin turning on its own again. That’s because the auto-orientation is still active and your trajectory is changing (since gravity is still acting), or it reversed if you passed the point. That’s why it is a very good practice to turn off the Retrograde orientation (just click again on the respective button) when you’re near the end of the deceleration process. That way, you won’t feel lost when the ship turns and you have no idea where you’re going anymore. Another useful thing to do not only on this situation, but in every situation that is possible, is to leave the Kill rotation option on. This will make the ship stop rotating if you’re not actively rotating it. When you activate any orientation, it’ll turn off automatically, so, whenever you’re not using an auto-orientation function, enable Kill rotation!
When you’re going at less than 100 m/s you don’t have to change your orientation again, you can kill the main engines and just use the thrusters for the final “stop”. You may struggle a bit at first, so keep trying until your velocity is 0 m/s. If you were paying attention to what you’re reading, you may be thinking I must be crazy, because I said earlier that you shouldn’t spend more than a few seconds adjusting your velocity at less than 10 m/s. Yes, these are contradictory, but I stand by what I just said: keep trying until your velocity is 0 m/s. It’ll never happen, because gravity will always increase your velocity towards Earth. But it’s good to practice here all the rotations, orientations, thrusters and etc, so you have a good feeling of when to use each of them. Decelerating is THE most important skill to learn before attempting anything else. You’ll use it all the time, so take your time on this step, and learn it well.
When your velocity is low enough and all engines are off, it’s time to align your ship to an orbit. You may be tempted to activate the Prograde orientation, because it makes the ship face the orbit trajectory. Well, go ahead and do that. It is not what you expected, right? Now activate Rotate to target. It’s the same, right? That’s because Prograde makes your ship face the direction you are going! In this case, you are falling towards Earth, so that’s where your ship will point.
To enter a stable orbit, you have to estimate its trajectory. Try to imagine a tangent line on Earth’s surface, and imagine it is now close to you. You have to align your ship with this imaginary tangent. Use all the rotation keys to help you with this (q, e, numpad 8, 2, 4, 6)! It doesn’t have to be perfect.
Pro tip: Think you got it? I trust you made it close enough, and it’d probably be fine. But, there is an easier and more reliable way: Activate Horizon orientation. Your ship will now face a perfect tangent with Earth! You can change the orbit direction if you want, using numpad 4 and 6 only. You have to deactivate the auto orientation, though, and as before, I recommend that you enable Kill rotation.
Now all you have to do is go full throttle ahead until the orbit is stable! But be careful and always watch the orbital parameters on the right part of the screen!
As soon as Rperi gets bigger than Rsmin, the orbit will be stable. Turn off your engines at this point, and click on View ship trajectory. Let’s see what we have (your situation may be a little different, but the overall idea also applies):
Fig. 2.11: First stable orbit.
“Is this really a stable orbit?”, you might be wondering. It is. But look at that, there’s a point where it seems the ship will crash on Earth! That’s because one of the axis is a lot bigger than the other. Remember how we started about 25000 km away from the center of the Earth? That will be the major axis (Rapo), and what we did when accelerating was simply increase Rperi until it was away from the surface of the planet, roughly above its radius. Remember what the orbital parameter ‘e’ means? If you don’t, it’s the orbit’s eccentricity. The lower its value, the more circular the orbit will be. It’s currently at 0.558, a very high value! And what about V1? It’s the velocity needed for a circular orbit at the current height (4.14 km/s). Notice how the ship’s velocity is below that, at 2.75 km/s.
- Make it circular.
You don’t really have to do this, but it’s a good practice, to feel the control you have on your ship’s orbit. Reset the camera (Center on ship button), and start the engines again! Wait until Rperi is very close to Rapo (both will change, but Rapo changes a lot slower than Rperi) and then kill the engines (z). Be careful, because the rate of change of these values grows exponentially! They’ll change faster the longer you accelerate! You now have an almost circular orbit! Take a look at it with the trajectory view:
Fig. 2.12: An almost circular orbit.
Take a moment to appreciate the beauty of what you accomplished! Your ship will stay on this course forever and ever, until you decide to take it somewhere else. Check your velocity, it should be very close to V1. Mine is bigger, because I accelerated for too long. Also, take a look at the eccentricity. It’s a lot lower than before, but…
Pro tip: Do you feel that? That “itch” to make it even more perfect? For the OCD people, I’ll teach you how to reach a 99.9999% perfect circular orbit. First of all, adjust your velocity. If it’s lower than V1, accelerate forward, if it’s higher, backwards. Do this until your speed is the same as V1. Check your eccentricity. Are you satisfied with that? Of course not, you have OCD! So now, use your thrusters (w, a, s, d, r, f) to decrease the value of ‘e’ as much as possible. Go forward/backward, left/right, up/down, then repeat. Use short keystrokes. Be gentle. This is my result:
Fig. 2.13: As perfectly circular as it gets.
Check my eccentricity. Were you able to go below that? If you did, wow, congratulations! It’s really hard to get lower than 0.001, so congratulations anyway if you reached that!
You are now on a stable almost perfectly circular orbit! Change your orientation to Prograde, and admire the beauty of our home planet! Accelerate time if you want!
What you learned here applies to any planet, moon or star! Just remember to check all the information the HUD gives you, and act accordingly.
The only thing I didn’t mention here is Rsmax. If you try to orbit a celestial body at a distance higher than that, there is probably another body whose gravity effects are more significant than your target’s at that point. This is defined by something called the Sphere of Influence radius. This doesn’t mean the weaker gravity is discarded, it’s still there, and it’ll still influence your orbit!
Ready for your next lesson? Let’s go then!
2.5. Reentry and Landing
There is a very easy way to land. Set your ship to Retrograde orientation, stop, and let it fall! Of course, you’ll be dead if you attempt this in real life, so we’re definitely not doing that. You’re here to learn, and learn it the right way!
I’m assuming you’re still on the ship’s cockpit, right? On a stable orbit? Let’s simply continue from that point! If you’re not, please take your ship to orbit (because I’m sure you learned how to do that).
As before, I’ll accompany you with my ship on all steps! Notice: There are many ways to reentry the atmosphere, and it can be very different to land on a planet without atmosphere, or moon. I’ll tell you the safest method, and on section 3.5 I’ll go over the method I enjoy the most! (But surely not the safest one…)
Pro tip: It is really unlikely that you’ll be able to safely enter the atmosphere and land the ship on your first try. So, before attempting the next steps, create as many Skylone ships as you think will be necessary. I’d go with at least 3. That way, when you crash your simulator ship, you can simply take control of another that’ll be waiting for you up there, in the same orbit as the original.
- Align and decelerate.
Basically, we want to decrease our orbit radiuses until we’re in the atmosphere (or close to the planet’s surface). To do this, activate Horizon orientation, wait for the alignment, and then use your back thrusters to decelerate. You can use retro engines too, but you usually will not need that much power. Activate trajectory view, that’ll help you a lot! Wait until your path (the filled green circle) “touches” the planet’s edge, turn engines off, and then disable auto orientation to be able to Kill rotation (let’s call this process of aligning and then killing rotation ‘Align and Kill’). After that, you should be in a situation similar to this:
Fig. 2.14: Ship trajectory almost “touching” Earth.
See how the orbit is not stable anymore? That’s not a problem, since we want to land. Notice how I stopped when Rperi is just below Rsmin. This means that we’re on a collision course! But don’t worry, everything’s under control...
- Tweak landing spot.
You’ll land very close to where the trajectory touches the planet, but maybe that’s not exactly where you want to be. You can tweak the position using your thrusters, but be careful, because if the descent path is too steep, you’ll have problems landing! It’s best to use Prograde orientation for this.
You can’t push it much to the sides, so it’s better to align your orbit to where you want to land when entering it! I decided to land somewhere on Australia:
Fig. 2.15: Landing on the Outback...
You may struggle with this at first, but don’t give up! It’s totally possible, just takes practice!
Now you have to wait a while. You can speed up time if you want, but carefully! It is possible that while you wait, Earth will rotate enough to completely change your landing spot! You can try and make small corrections, but if it takes too long, it may be beyond the ship’s capabilities to maintain it at the right place, while also keeping the approach process safe. The closer your orbit is, the faster you’ll land, and the more accurate your landing place will be.
Keep an eye to the Tperi, it’s close to the time before you touch the ground, but watch your Elevation too!
I suggest that at ~100km you Align and Kill (Horizon) and go back to the normal view. Because you’ll probably need to…
- Make last-minute corrections!
On my case, I didn’t decelerate enough, so even though it seemed I was going to touch the surface, I could see it wasn’t really going to happen, because the filled green circle was way above the surface. Maybe this isn’t the case for you, or maybe you have another evident problem. No worries, you have time to make the corrections you need. I simply decelerated even more:
Fig. 2.16: After the last corrections.
Now change your HUD to Horizon and wait again, watching your elevation very closely, because at ~40km, something very interesting will happen...
- Control your attitude.
I’m not lecturing you. This means that you have to be ready to rotate your ship up! When the atmosphere is thick enough, your ship will drop its nose straight down, so it’s your job to keep it controlled! If you followed my advice and Kill rotation is enabled, it’ll start going up and down on its own, as it tries to stop the rotation. Using Numpad 8, try to set your attitude between 10 and 20 degrees. The lower it is, the faster you’ll go (and the faster you’ll fall), so 15 degrees is a good target value. You’ll eventually notice you’re in complete control of your ship again! There are not many feelings in the universe that match the satisfaction you’ll feel! Luckily, your ship will be like this:
Fig. 2.17: A successful reentry.
- Control the descent.
Here’s what you have to do: control your attitude (yeah, we’re still doing that) so you have a steady and controllable descent rate, and a forward speed fast enough to still generate lift. Remember that the lower your attitude, the faster you’ll go. Use your thrusters or main engine if you have to, but be very, very careful! Keep your speed above a couple hundred m/s and we’re good.
Now let’s take a closer look at all the information we have. First of all, let’s see what the selected object info tells us (if you don’t have the ship selected, click on it now). The air and surface velocities (TAS and TSS) will usually be very close, depending on the wind. They indicate your forward speed. In atmospheric flight, you have to keep track of these two velocities: Forward and Vertical.
Gravity acceleration will increase as you get closer to the surface. It’s always good to remember that it’s there! When flying, if your forward velocity is high enough, the ship’s wings and other aerodynamic elements will generate a lift force that balances gravity. The faster you go (and the thicker the atmosphere or higher the pressure), the more lift that is generated. That’s why you have to be careful when accelerating, because you may go straight up!
You’ll eventually notice that the forward speed will keep dropping, even when your main engines are at 100%. That’s the drag force acting. The friction between the ship and the atmosphere slows it down, and the effect increases as you descend, because the air density increases. This is indicated by the Aero Accel value.
If you are patient, you’ll eventually be very close to the ground, and at a reasonable speed (100 m/s is ok). Pay attention to your Elevation at all times! This is what you want:
Fig. 2.18: Almost there!
It’s possible you’ll be above water, and not ground. It doesn’t matter, this ship can land on liquids, and the concepts are the same.
Now, to land, you can simply let the ship touch the ground, and it’ll stop. That’s fine your speed is low, there will be no damage. A more interesting way to do it, though, is zero your forward and vertical speeds, and then use the hover engines and/or upwards thrust to carefully let the ship go down. Or you can just hit the Hold Altitude button, then use the downward thrusters to go down.
That was tough, wasn’t it? It’s alright to fail many times on this. It takes practice to be able to successfully land a ship on the first try. If you made it without messing up, go away, you’re probably already a skilled pilot and don’t need lessons!
One thing I have to remind you, is that every planet will have a different atmosphere, with different pressures and densities (and different gravity as well). This makes every entry different, and it’s up to you to figure out when to start decelerating, the vertical speed to maintain, how the atmospheric lift will affect the ship, and so on. There’s no easy way to know how the ship will behave, so it’s best to just play safe, be patient, act ahead, and don’t go too fast! Oh, and every ship is different… And on moons and planets with no atmosphere, nothing of this applies! So yeah, it’s tough business.
2.6. Taking-off (and entering a stable orbit)
Compared to the previous lesson, this will be a piece of cake! Seriously, you’ll laugh at it. It is here at this point, and not before, for continuity reasons.
So you just landed your ship. After unloading the goods you brought, relaxing at one of Earth’s fine beaches, and loading more goods, it’s time to continue your journey!
- Take off.
To take off, simply start your hover engines, and increase their power slowly. When you feel you’re going up (don’t go too much!), stop increasing their power, and start your main engines. Do the same with them: increase the throttle slowly, while managing your attitude. Keep it between 5 and 10 degrees. At 1 km altitude, go ahead and max the main engines power, and turn the hovers off. Proceed increasing your attitude slowly.
- Up, up and away!
At 20 km altitude, it’s safe to turn your ship straight up, that is, 90 degrees. At this point, change the HUD mode to Orbital.
- Manage your ascend.
Control your speed and keep an eye on the distance to Earth’s center, and try to reach your desired orbital radius going slower than 5 km/s.
The most important skill is here again. Align and Kill (Retrograde), and start decelerating. When your speed is less than 10 m/s, you can rest.
- Enter a stable circular orbit.
Now follow the instructions from Section 2.4, and you’re done!
When you have more experience, you’ll be able to take off (not going straight up) and enter a stable orbit directly, without having to stop your ship.
2.7. The auto-pilot
This section is less of a lesson, and more of a description. Now that you learned the very basics of spaceflight, you are “cleared” to use the autopilot when you feel the need. I’ll tell you though, it’s not as cool as being in complete control!
- Autopilot orientations:
We already used a lot of these! They simply orientate the ship into a certain direction, and keep it there. These are a very good convenience, to be used at will!
- Kill rotation:
Another excellent convenience. Due to inertia, your ship would continue to rotate after you let go of the buttons, even if it was a simple tap. This function makes the rotation stop when there is no intentional input.
- Hold altitude:
This is useful, but you don’t really have to use it. When close to the surface, it will make the ship stay at the same height. You need a hover engine for this!
- Sync velocity:
Used mainly for docking, but you can use when any other celestial body is your target. If you want to decelerate automatically without any worries, use this.
- Go to/Warp to:
These are the not-fun functions. Activating any of these will make your ship go automatically to your target using the Warp Drive or not. It’ll plot the course, take care of accelerating and decelerating. Not fun at all!
But we’ll use them any way for the final part, that is...
2.8. Basic Level Exam: To the Moon and back!
This is it, time to prove you learned something! Your task is simple:
- Start with a ship on Earth’s surface.
- Take-off, and enter a stable orbit (doesn’t need to be perfectly circular).
- Wait in orbit until the Moon is visible.
- Set the Moon as your target. Reference body too, if you want, but you can do this later.
- Use the autopilot to go there. You’ll end up at a convenient distance to enter orbit. Do that now.
- Admire the scenery.
- Set Earth as your target and autopilot there.
- Enter orbit.
- Receive Basic Flight School Certificate!
- You’ll probably want to accelerate time at some points. But never when the ship is turning, or about to turn! Be very careful! And I mean, very, very careful!
- Resume normal time speed when the ship is about to do something. You’ll know because there’ll often be a timer on the selected object info, or if the velocity is getting close to zero. And when I say “about to”, I mean at least two minutes. You may end up on the other side of the system if you’re not careful with this.
- Take a look at Earth when the autopilot is accelerating away. It’s a beautiful sight.
- Notice that the Moon doesn’t have atmosphere, so you won’t glide when descending, you’ll just fall down like a brick.
- Also notice that the Moon’s gravity is almost ten times weaker than Earth’s.
- Wait until the autopilot finishes completely. You’ll know it’s done when it finishes syncing velocity, and you’ll begin falling.