Flight to the moon landing on the lunar base

Long time I did not have new posts on Orbiter'u. Therefore, today we will talk about the staff of the game called Delta-glider, and also, having taken off from Earth, we fly to the lunar base. Despite the fantastic nature of the task, it should be quite curious - the task of braking and landing on the moon is not as simple as it may seem. The fact is that the moon does not have an atmosphere, so it will have to slow down with engines.

Delta glider

This ship is in the basic delivery of the game. It has fantastic options:

• Weight empty : 11 tons normal, 13 tons modification with hypersonic ramjet engines. Approximately the empty MiG-29 weighs so much.
• Fuel mass : 13 tons.
• Length : 17.76 m.
• Wingspan : 17.86 m. Such length and wingspan are comparable with average WWII bombers ( Do-17 ) or A-10 attack aircraft.
• Marching engines : 2 * 160 kN (slightly more than RD-0124 )
• Specific impulse of the main engines : ~ 4000 s. Such parameters are possessed by the YARD , for good reason, on the model of the vehicle in the engine compartment, the radiation hazard icon.

This combination of parameters allows you to independently start from Earth, go into orbit, dock with the ISS and go back, not including the "infinite fuel" mode. In fact, this is the very dream of SSTO , the realization of which so far does not even loom on the horizon.
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Also, the device has lifting engines that allow you to make a vertical take-off and landing, and wings, allowing you to maneuver in the atmosphere. The combination of these properties makes the Delta-glider an excellent device for training and flying for pleasure.

Flight preparation

Except for Orbiter, no add-ons are needed.

Flight plan

Our mission will be divided into simple steps. Therefore, on the one hand, it will be very inefficient in terms of fuel (and we will turn on the “endless fuel” mode). Also, it will be unrealistic - the teams of ballistics calculate the real trajectory apparatus, which makes flights much more efficient. But, on the other hand, separate stages will be simple and will clearly explain the physics of flight. Our flight plan will consist of the following steps:

1. Starting from Earth and entering a low circular orbit.
2. The combination of the planes of the orbits.
3. Acceleration to the moon.
4. Going into orbit of the moon.
5. Combining the plane of the orbit with the landing site.
6. Braking and landing.

Definitions used

The apocenter is the highest point of the orbit. For the orbit around the Earth, the name "apogee" is also used.
The pericenter is the lowest point of the orbit. For the orbit around the Earth, the name perigee is also used.
The inclination of the orbit - the angle between the plane of the orbit and the other plane (the plane passing through the equator of the Earth or the plane of the orbit of another body)
The ascending node is the point at which the orbit intersects the plane of the Earth's equator or the plane of the orbit of another body, being “above” it. “Above” and “below” are determined by the conditional north and south poles.
The descending node is the point at which the orbit intersects the plane of the Earth's equator or the plane of the orbit of another body, being “below” it. “Above” and “below” are determined by the conditional north and south poles.
For example, if we are talking about the orbit of the moon around the earth, the picture will be as follows:

Stage 1. Starting from the Earth and entering a low circular orbit

After starting the game, first go to the "Parameters" section and set the infinite fuel mode:



In addition to the obvious bonus of permissible errors for the flight, this mode will give us a constant acceleration of the ship, which will be very convenient for landing.
Then run the “DG-S ready for takeoff” script:



DG-S is a version with air-jet engines, we do not need them, but this scenario is convenient because we are already standing on the runway.



Switch to the view from the cockpit by pressing F1 . By pressing F8, we successively switch the cockpit to the “glass cockpit” mode.



Both multifunctional displays should be switched to something more convenient than the landing indicators and the map. Switch the left MFD to the “Surface” mode by pressing the Left Shift - F1 , the Left Shift - S. Right MFD switch in the "Orbit" - Right Shift - F1 , Right Shift - O. Check that the ship's orbit is not projected onto the ecliptic (Proj: SHP mode, PRJ button on MFD), and the orbit height is counted from the surface, not the center of the Earth (Necessary mode — small ApA and PeA values ​​— pericenter and apocenter heights, DST button on mfd). The correct result will look like this:



A numeric keypad is used to control ship maneuvers. At the beginning of the scenario, the orientation engines are turned off, and the buttons on the numeric keypad control only aerodynamic surfaces - ailerons and rudders. Before takeoff, we will set the elevator trimmer all the way up, pressing and holding Delete over the block of cursor keys. We launch the sustainer engine and fix it by pressing Num + and, without releasing, Ctrl . With the trimmer fully raised, the Delta glider will take off on its own.



After takeoff, we remove the landing gear ( G ) and start turning to an azimuth of 90 °. Why 90 °? In this case, we will accelerate in the direction of the Earth’s rotation, and the inclination of our orbit will be equal to the latitude of the launch site (~ 30 ° for Cape Canaveral, from where we took off). After turning, we set the pitch angle to 30 ° by manipulating the trimmer ( Insert - down, Delete - up).



As the height increases, the air will become less frequent, and trimmers will not be enough to maintain a constant pitch of 30 °. We turn on the orientation engines by pressing the ROT button from the left-top and maintaining the pitch angle in the KillRot stabilization mode ( Num 5 ). But at an altitude of ~ 20 km, this mode will no longer cope normally. You can help trimmers active management (more convenient if you have a joystick). But the most elegant option is the turn of the main engines. The fact is that the Delta-glider, like many modern missiles, sustainers can turn on a gimbal, creating a control moment. In order to change the rotation angle of the engines, we switch the cockpit to 2D mode (by pressing F8 ). Controlling the vertical angle of the engines from the left-top, clicking on the yellow dots changes the position of both engines at once:



Keeping the pitch 30 ° continue acceleration. Above 50 km, you can leave only KillRot mode by setting the engine angle 0 ° with the Center button under the engine vertical angle control buttons, and switch to a more convenient “glass cockpit” mode. At an altitude of ~ 70 km while maintaining a pitch angle of 30 ° there will be a section of a slight decrease, no need to be intimidated. When the vehicle rises to 70 km, the speed becomes insufficient to create any significant lift. But during the inertial ascent and a small descent, the speed again begins to suffice to create lift with the wings, and the second lifting cycle begins. You can visually look at this process by turning on the display of forces acting on the device ( Ctrl - F9 , in the Forces tab, check the boxes).



We continue to accelerate until on the orbital indicator the height of the apocenter is 200 km. Upon reaching this parameter, turn off the engines by pressing Num * .



We translate the indicator on the windshield into the orbital mode (the H button) and occupy the position along the orbital velocity vector (nose forward) - the [ or PROGRD button below.



Not far from the apocenter point (transparent circle on MFD “Orbit”) we turn on the engines again. Accelerate to approximately a circular orbit, the height of the pericenter should not be below 150 km. Result:



Let's translate the device into the orbital configuration. The fact is that the brake motors are located in the toe of the wing and at the start are covered with aerodynamic fairings. They could be opened at the start - there are no damage models in the Orbiter, but it is more interesting. So, open the “control elements” menu ( Ctrl - Space ) and press the Retro Doors - Open button.



Now we can not only accelerate to Num + but also slow down to Num- . Brake engines are less powerful than cruising engines, but they are convenient to use to perform precise maneuvers.

So we are in low orbit of the earth. This orbit is stable, so I recommend saving it by pressing Ctrl-S . Saves are in the Quicksave scripts folder:

Stage 2. Combining the planes of the orbits

In order to find out the difference of the orbits inclination, we switch the right MFD to the “Alignment of the orbit planes” mode - Right Shift -F1 , Right Shift - A. We select the moon as the target - right shift - t , in the menu select celestial bodies - moon:



The 47 ° angle vividly demonstrates the saying “there is strength — mind is not necessary”. In real life, the devices to the Moon are trying to be allowed into the so-called starting windows when the angle between the planes is minimal. The window to the moon opens once a lunar month. In addition, the team of ballistics can calculate such a starting window that the angle between the planes of the orbits will beautifully turn into the inclination of the orbit of the spacecraft around the moon. We use quite limited tools and, moreover, we want to go to the moon now, without waiting. Therefore, it is necessary to combine the planes of the orbits so that we can begin acceleration to the Moon from any point of our orbit.
To combine the planes of the orbits, we must accelerate "up" on the descending node and "down" on the ascending one. The nearest node is descending (DN - Descending node), so we will occupy the position normal to the orbital plane. This will help us automatic orientation. Button ; the keyboard or the NML + button on the screen below is an automatic occupation of the position "up" perpendicular to the orbit plane, ' it is e , or NML- on the screen - down.



In the area of ​​the node we start overclocking. Such a large angle means that several maneuvers are required.



After the first maneuver, the angle decreased by half. Repeat on the ascending node. In order not to be bored waiting for the node, use the acceleration of time - the T button accelerates time 10 times, R - slows down 10 times. Do not abuse the acceleration, when the automatic orientation mode is on, the ship may start to accelerate on acceleration over 1000x.
After the second or third maneuver, the relative angle will tend to 0:



Stage completed, do not forget to save.

Stage 3. Acceleration to the Moon

To disperse to the moon, we need MFD "Transition". Turn it on the right - Right Shift - F1 , Right Shift - X. Let's select the moon for the purpose ( Right Shift - T , Celestial bodies - Moon). Turn on the maneuver planning mode - the HTO button on the MFD. HTO is the Hohmann Transfer Orbit - Goman path , a way to move between orbits with a minimum of fuel costs. A dotted radius appears. This radius denotes the maneuver point. We can move it with the Right Shift - < and > buttons. We can also adjust the calculated impulse with the Right Shift - + and - buttons.



Combine the point of our expected position with the point of the expected position of the moon.



The DTe parameter is the time before the start of the maneuver. DV is a necessary speed increment. We should start acceleration some time before reaching the maneuver point in order to at least partially compensate for the lateral component of acceleration along the orbital velocity vector:



Do not forget to take a position on the orbital velocity vector in advance. We accelerate:



It is very important to remember our acceleration - 11.8 m / s ^ 2. This is the acceleration with which we will slow down at the moon, and it will be useful to us for calculations.



Overclocking is over. For the Earth-Moon flight such accuracy is quite sufficient; no additional correction is required. Do not forget to save.

Stage 4. Going to the orbit of the moon

Getting ready for the flight to the moon. We stabilize the device with the KillRot mode. It will turn off automatically, and we can safely accelerate time.
To avoid being bored, turn on the music:



During the flight to the moon, I recommend paying attention to the mutual position of us and the moon. First, we will overtake it, but closer to the apocenter, our speed will become almost imperceptible, and the Moon will catch up with us. All under the second law of Kepler . When approaching the Moon, pay attention to the change in our orbit - the Moon is behind us and inhibits our movement forward with its gravity.

When the distance to the moon decreases, it is worth checking our orbit - are we aiming too accurately and not crashing into the moon? Switch the right MFD to the "Orbit" mode ( Right Shift - F1 , Right Shift - O ). You need to make sure that the MFD is in orbit around the moon. If the MFD is in orbit mode around the Earth or the Sun, you must manually switch it to the orbit mode around the moon by pressing the Right Shift - R , in the menu select Moon . If necessary, by pressing the HUD button on the MFD, transfer the indicator on the windshield to Orbit Moon mode. It is necessary to wait until the gravitational influence of the Moon becomes overwhelming - the indicator G at the bottom of the MFD is not less than 0.9-0.95. Otherwise, the influence of the Earth will strongly distort the final orbit. So, it turns out that we aimed too accurately and hit the moon if we do nothing:



It is necessary to carry out a trajectory correction maneuver. To do this, turn the ship 90 ° to the right of the direction of travel (there are goniometric tools in the interface). Why right? The direction marker of our movement is to the right of the center of the moon, so we will have to maneuver less. But if you wish, you can move left, up or down. There is no autopilot for this mode, it will be necessary to hold the course 90 ° to the right manually. We are starting a maneuver:



When the height of the pericenter is 40-80 km, we finish the maneuver.



Shortly before the pericenter, we occupy a position against the orbital velocity vector (stern ahead) and slow down, moving to a circular orbit:



Great, we're in a low circular orbit around the moon. Do not forget to save.

Stage 5. Combining the plane of the orbit with the landing site

Turn on the map mode on the right MFD ( Right Shift - F1 , Right Shift - M ). Select the lunar base "Brighton Beach" as the target ( Right Shift - T , in the menu choose Spaceports - Brighton Beach ):



The green line is our trajectory. Yeah, so we won't get into Brighton Beach. It is necessary to change the inclination of the orbit to fly over the base. To do this, we occupy the position of NML + or NML- normal to the orbital velocity vector up or down (for an orbit with a nearly zero inclination, this is not important) and change the inclination of the orbit until the green path of the trajectory passes over the base. It is better not to change the inclination of the orbit at any point, but at about 90 ° of latitude to the left or right of the base. One cell on the map is 30 ° latitude and longitude.



The result of the maneuver:



Unfortunately, the automatics did not have time to hold the ship strictly perpendicular to the orbital velocity vector, and our orbit deteriorated. It will be necessary to switch to MFD "Orbit" and return to a circular orbit. Spend another round for two tasks:

1. Make sure that we aim precisely.
2. Reduce the orbit to 10-15 km.

The map scale is changed with the ZM + and ZM- buttons. The ship tracking mode is activated with the TRK button.
After that, do not forget to save. The most interesting begins - we are landing.

Stage 6. Braking and accurate fit

By the way, the fantastic base "Brighton Beach", judging by the coordinates, is located in the southern part of the Rainbow Bay:



Not far to the south of the village "Lunokhod-1", and 400 km to the east - the Chinese "Jade hare".
By the way, if you wish, you can turn on the display of surface marks (Ctrl - F9, Planetarium - Surface tab) and practice in selenography:



What is the difficulty of landing on a celestial body without an atmosphere? There is no atmosphere to slow down about it, wings and parachutes will not help us. It is necessary to redeem one and a half kilometers per second of orbital speed and not to fall at the same time hundreds of kilometers from the target. If we start to slow down, then our pericenter is under the surface, and it is necessary to fend off the fall, at the same time slowing down the speed, in order to finally go to a hanging near the target. In real flights, most of the maneuver was controlled by a computer, the astronauts on the Apollo interfered with the control already in the final leg of the flight. And we have the poverty of computing power is compensated by infinite fuel. But without mathematics, it's all the same anywhere. We need to find the distance from which to start braking in order to be in the base area. Acceleration and mass of us, praise to the infinite fuel, are constant, so school formulas will suffice:
How long will we slow down? The initial speed is known - 1658 m / s. The final - 0. Acceleration, we remember from the previous stages - 11.8 m / s. V = V ₀ -a * t, therefore t = (VV ₀ ) / a = (1658-0) / 11,8 = 140 seconds .
What is the distance to start braking? S = V ₀ * t- (a * t ² ) / 2 = 1658 * 140- (11.8 * 140 * 140) / 2 = 232120-115640 = 116480 m .
We will slow the stern forward, so it will be more convenient to fly over the base. Take a stock of 10% and start braking for 106 km from the base.
We need to take the correct position for deceleration — against the vector of orbital velocity, “belly” toward the moon. To do this, turn on the “horizon level” mode — L or the HORZ LVL button at the bottom of the screen and turn the ship stern forward manually:



I recommend to save about 500 kilometers from the base.
Over 106 km we start braking. After the vertical speed becomes noticeable, we will begin to parry it with lifting motors ( Num 0 - increase thrust, Num. - reduce thrust). Avoid high vertical speed and high vertical acceleration!



Slowed down. We turn off the main engines, we continue to gradually decrease on lifting engines.



The base is already visible below. We aim with a marker of the direction of movement on it, gradually reduce the forward and vertical speeds and release the chassis:



The main thing - to move smoothly, not to make sudden movements. Orientation motors can be switched to offset mode ( Num / ) for precise maneuvering.



Base gradually manifested. A row of white stripes is not a runway, but a monorail, there is no need to sit there. Our goal is landing sites, standing "daisy" around the main building:



Left just a little bit. Note that the speed is almost redeemed.



You can switch to the appearance of F1 , in order to better control the process of landing.



There is a landing!



I recommend saving the script - then you may want to fly, for example, to Mars, and taking off from the moon and going into orbit is easier.

Conclusion

I do not know if we will live to a real lunar base, but such a virtual flight is an interesting adventure. And cognitive.
If you want to learn something deeper, there is a manual translated into Russian . Well and other posts of the Orbiter series .