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Introduction

The Demonstrate Engine Ignition In Space contract will be your space program's second foray into developing orbital flight, and is a major milestone in your career. Designing this rocket will require knowledge of vacuum attitude control and propellant settling design and is the second step towards designing orbital rockets of your own! The rocket, tech-wise, is slightly more technologically advanced than the previous chapter's guided rocket, as it uses better engines configs. After completing this contract, you are ready to move onto true orbital flight.

Contents

• 1: Contract Requirements
• 2: Creating The Upper Stages
• 3: Creating The Lower Stage
• 4: Running A Sim
• 5: Completing The Contract
• 6: The Next Step

1: Contract Requirements

The requirements of this contract are very similar to the In-Space Attitude Control milestone, with two important distinctions:

1. You only need to maintain active avionics control until you've reached 140km of altitude.
2. You need to perform a burn of at least 2500 m/s after the attitude control exercises whilst holding a specific attitude without a roll requirement.
3. You now need to reach at least 1200 km downrange.

These requirements combined inform that you need guidance for the attitude control exercises, but may perform the burn with an unguided spin-stabilised stage, as long as it holds a specific pitch and heading.

In order to achieve these objectives with a sensible rocket, in addition to the nodes required for the previous tutorial, the Early Rocketry and Early Tracking systems tech nodes are required, marked here in orange:

2: Creating The Upper Stages

Creating the stage that will perform the in-space burn is trivial. You need a science core set to Post-War Avionics with 300 kJ of EC, a HP Al Fuselage Conventional Structure Procedural Tank, and an Aerobee with the XASR-2 config selected. The XASR-2 uses helium pressurant compared to the nitrogen pressurant of the XASR-1 and is the Aerobee's most efficient config. If you've done everything the same as in this tutorial, you'll now have a stage with 2507 m/s of Delta-V. For configuration details, see this screenshot:

Now you need to get this stage into space somehow. For this, you can use the rocket you designed in the previous chapter, though it will require a few modifications. From this point on, the tutorial assumes you made the avionics unit of that rocket its root part. First, go to the craft loading menu, select your previous design, and click the 'Merge' button at the bottom of the craft loading UI:

Now that you've got your previous design loaded up, grab whatever decoupler you like from the parts list and attach it to the bottom of the upper stage you just made, fitting it neatly around the Aerobee:

Now just attach your previous design to the bottom of this decoupler, resize its nose diameter to match that of the decoupler, and give it a funky shape you like. We'll be coming back to this avionics unit later to reconfigure its Controllable mass.

Finally, select the RCS Blocks and switch them to HTP (High Test Peroxide). Temporarily remove the first stage, click the Remove All Tanks button on the tanks that are hidden in the interstage, and fill them with the HTP+Helium mix for our RCS. As HTP is a much more efficient reaction fuel than Helium, Nitrogen, or even the later unlocked Nitrous Oxide, we now only need a single tank of it. If everything's gone correctly so far, you should be seeing 32 m/s of RCS Delta-V in the MJ Delta-V Stats window. Don't forget to reattach the first stage.

3: Upgrading The Lower Stage

Compared to your previous rocket, this new upper stage is much heavier. In order to lift it high and far enough, you're going to need a stronger first stage. For this you can use the RD-101 config on the RD-100. Switch the configuration in the Engine Configuration GUI and don't forget to swap the fuel mix in its tank.

The RD-101 has 33% more thrust than the previous RD-100 config and also burns more fuel. You will need to resize the tank to allow it to hold this additional fuel. If you only lengthen the tank, this will require a very tall and expensive LC. Rather than pay for such an expensive LC modification, instead increase the tank diameter to 1.7330m and select the 4:3-Short nose. Change the tank length to 7m.

Notice how the rocket is now nearly 18 tons? This is where you go back to your Near-Earth avionics unit and increase its controllable mass to 18 tons. Be sure to hit the Apply (preserve dimensions) button so it doesn't change shape.

4: Running A Sim

Make sure your staging is correct before running a sim. In stage 3 you should have the RD-101. In stage 2 you should have your launch clamps. In stage 1 you should have the RCS and the decoupler it is attached to. In stage 0 you should have the Aerobee and its decoupler.

Once you've confirmed this and saved your design, head out into the simulation. As the procedure for the ascent and attitude control portions are the same as the previous tutorial it will not be covered again here, but do be mindful the attitudes themselves are different. For reference, here is what your settings should look like on the pad:

Once you've completed the attitude control excercises, you should be nearing your apoapsis. Use Smart A.S.S. to point at HDG 90 and PIT 0, and hold either the Q or E key to start rolling. Keep holding the roll key you've chosen until you reach a roll rate of about 0.33 revolutions per second. Finally, you need to settle the propellant for your upper stage. Throttle up (settling propellant in this way needs the Use RCS to ullage setting to be enabled in utilities) and stage when the PAW of the Aerobee says Propellant: Very Stable (100%).

If all has gone well, your final stage will gently roll and experience minimal precession whilst burning its 2500 m/s of Delta-V. You should reach around 1500 km of downrange distance. Achieve this, and you will have completed all requirements of the contract.

5: Completing The Contract

All that's left now is to actually build the rocket! Since your new engine burns a new fuel, Ethanol90, as well as exceeding your pad weight limit of 15 tons, you'll need to modify your LC. If you've been following the tutorials, this modification should take seven days and cost 1844 funds. Select your LC in the Integration Info window, click Modify, and in the Modify Launch Complex that pops up click Modify again. Once the modification completes, put your rocket into the build queue of the LC and fly the mission for real once it finishes building and rolling out!

6: The Next Step

Now that you know how to orient and ignite a rocket stage in space, it is time for you to complete the Early Rocket Development program. Only if there's specific optional contracts you wish to complete for confidence should you keep the program around for a little longer. Otherwise you should head into the Administration Building, and move onto Early Satellites (Light) if you want to build rockets with a single first-stage engine. Alternatively, pick Early Satellites (Heavy) if you want to build rockets with multiple first-stage engines. The next chapter will cover how to build a fully-guided two stage rocket for the Early Satellites (Light) program. You can of course apply the theory of unguided burns you learned here to design something lighter.

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