Difference between revisions of "Tutorial: Sputnik 1"

Revision as of 15:39, 17 August 2013

Welcome to the first entry of learning Kerbal Space Program through a re-enactment of historical key-missions of the spaceflight history of Earth. This tutorial assumes that you have completed the ingame tutorials so you know the basic controls.

Our first complete mission will be a recreation of the launch of Sputnik, the first man-made object to enter Earth's orbit. The successful launch of Sputnik in 1957 by the Soviet Union was a shock to the whole world. While the space programs by different branches of the US military were mostly impressing with explosions on launchpads unplanned vehicular disassemblies, nobody expected the Soviet Union to already be so far ahead in rocket science. The beeping sound of Sputniks transmitter - strong enough to be picked up by amateur radios all around the world - was a wake-up call for the West to finally start taking space exploration seriously. Now we are going to recreate this historic mission.

We will launch a satellite into space and bring it to a stable orbit. Space - for our purpose - starts at an altitude of 100km where the atmosphere doesn't affect objects anymore and thus allows them to enter an orbit which is stable for an indefinite amount of time.

To watch this tutorial in the form of a video(more brief, but more visual), click here.

Ship design

For this mission we will recreate the Soviet R7 rocket. The first stage is made up of four engines which surround a second stage engine with the payload on top.

Our vessel

• Payload stage
  • 1x Stayputnik Mk. 2
  • 1x Z-1k Rechargable Battery Bank
• Second stage
  • 1x TR-18A Stack Decoupler
  • 1x FL-R25 RCS Fuel Tank
  • 4x RV-105 RCS Thruster Block (symmetric radial-mounted)
  • 1x FL-T800 Fuel Tank
  • 1x LV-T30 Liquid Fuel Engine
• First stage
  • 4x TT-38K Radial Decoupler
  • 4x FL-T400 Fuel Tank
  • 4x Aerodynamic Nose Cone
  • 4x LV-T30 Liquid Fuel Engine

We need to add a battery bank to the payload, because the Stayputnik command module requires energy to stay operational. During the ascent the engines will generate energy, but after orbit insertion it will have to work on its own energy reserves. By itself it can store 5 units of energy which keeps it operational for just over 2 minutes. Afterwards it just becomes debris. The Z-500 adds another 500 units of energy which is enough to keep it operational for several orbits. Using the Z-100 battery packs would be more mass-effective, but unfortunately they aren't as elegant to integrate into a rocket design.

When you want your satellite to look more like the real Sputnik, you could also add four radially-mounted Communotron 16 antennas to the round part of the Stayputnik so that they face backwards in a 45° angle. But keep in mind that they don't do anything but making the mission more difficult by adding additional mass and drag to your rocket.

Note that the aerodynamic nose cones are technically just for show, because the current version of KSP (0.18.4) doesn't model atmospheric drag correctly. Any part you add to your rocket will make the drag worse, there is no way to reduce drag by adding more parts. Feel free to omit them when you don't care about aesthetics.

Mission phases

Lift-Off

Before you start your flight, switch on RCS and SAS so you have better control over your rocket. Also, switch your nav-ball from surface-mode to orbit-mode by clicking on the dial above it (it should read "Orbit 174.5m/s").

This phase is about getting out of the atmosphere as quickly as possible. The thick atmosphere around the ground creates drag which costs you fuel, so we will head straight up to get out of it. When you are ready, hold shift to set your throttle to maximum, and ignite your first stage by pressing space. Watch the nav-ball and keep your rocket pointed at the center for a perfectly vertical ascent. When the first stage has burnt all its fuel, drop it and ignite the second stage using space. Don't press space too often, or you will drop your payload.

Gravity-Turn

When you've reached an altitude of 10km (should be shortly after igniting the 2nd stage), air resistance becomes much less. Now we start to build up vertical speed so we get fast enough to get into a stable orbit. Do this by tipping your rocket into the direction of the yellow direction marker on the nav-ball (90° eastwards). While your rocket faces the direction marker, the marker will slowly fall towards the horizon. This is good. Keep your rocket pointed at the direction marker, so it slowly tips towards the horizontal plane.

Getting into a circular orbit

While you perform your gravity turn, switch to the map view so you can see your flight path and your apoapsis. You can switch on the nav-ball in orbital view by pressing the comma-key on the numeric keypad. Do this so you don't get off-course. Your goal now is to get your apoapsis to about 100km. We need some additional height because we aren't out of the atmosphere yet, so we will keep losing some height due to atmospheric drag.

When you reach your apoapsis, perform a prograde boost - orient your rocket horizontally pointing east and burn your remaining fuel to get into a circular orbit. Should you run out of fuel, remember that you likely still have plenty of monopropellant left from the ascent. Press H to use it to accelerate forward. It doesn't do much, but it can be enough to give you the crucial last few m/s to get into a stable orbit.

Dropping the payload

After you are in orbit, drop your payload using space. Thanks to the powerful separator it will be blasted forward while the engine stage drifts behind. Congratulations, you just made space history. Go into time-warp and watch your satellite orbit Kerbin gracefully.

What next?

A scientific satellite in orbit

Unfortunately the satellite still has a limited lifetime due to energy use. To extend its life further it needs some kind of energy source in the form of photovoltaic panels or a Radioisotope generator. When you have a sustainable energy supply, you can also add some scientific payloads like accelerometer, barometer, thermometer or gravimeter. Note that all of this will increase weight and atmospheric drag, so you will need to add some more tanks to your rocket.

When unmanned satellites become boring, it's time to get to the next stage of space exploration: your first manned mission.