DC‐Y instuctions

DC-Y build and flight instructions

Assembling

1. Place the avionics unit or crew compartment first.
2. Attach the nose cone to the node at the opening at the side.
3. Attach the body, flaps, and legs. Ensure the flaps are orientated the right direction!
4. If needed, attach the forward RCS thrusters at the bottom.

Pre-launch checks

1. Ensure the authority limiter for the flaps are set to 0.
2. Ensure deploy angle is set between 20-45°, you can adjust this later for rate of deceleration.

Flight profile

WARNING! DCY is a very hands on vehicle especially during reentry and descent, try practicing a few times!

Stock

1. Ignite the engines and liftoff as per usual.
2. If using the bimodal engines, switch to vacuum mode when your apoapsis is 60-70km.
3. You can switch off the sea-level engines either immediately, a little later, or leave them on until orbit.
4. You should now be in orbit.
5. Once payload is deployed, you should have around 550-800 m/s left, this will be enough to de-orbit and land. If you have too much, dump until the required amount if not it may be unstable while reentering. If you have too little, pray.
6. Before entry, deploy the flaps and turn the authority limiter to 45°.
7. Point prograde, if using MechJeb, use SVEL+ and set pitch to 5°.
8. Keep this attitude until you are below 300m/s after which you can flip around, preferably set the flaps' authority back to 0 for a more stable descent.
9. Land.

RO/RSS [Video instructions]

1. If using MechJeb, set the initial periapsis and apoapsis to 150km and a pitch rate of 0.4°/s. You may limit acceleration if needed. ALTERNATIVELY, use Smart ASS and manually fly to orbit if using the bimodal engines.
2. Lift of as per usual.
3. If using bimodal engines, switch to vacuum mode at 50km, you have to press the extend nozzle button manually. WARNING: MECHJEB DOES NOT WORK WITH THE BIMODAL ENGINE CONFIGS, you may be required to fly manually at this point.
4. If using bimodal engines, about a minute after switching, shutdown the sea-level engines.
5. After deploying your payload, leave no more than 600 m/s after deorbit for correct balance. Aim for a periapsis of 0km.
6. To prepare for entry, disable the RCS thrusters you placed at the bottom, and disable the pitch and yaw RCS thrusters for the body. Set the flaps' authority limiter to 45° and deploy angle between 20-45°. Ensure you are pointed prograde.
7. Upon entry, if using MechJeb, use SVEL+ and set pitch to 5°. Turn on descent mode and set it to around 15-20%. Heres how a properly configured DCY looks like for reentry
8. When below 70-65km, disable the pitch and yaw RCS thrusters on the nose, the flaps are now in control. Roll is still being provided by the RCS thrusters. If the vehicle is pitching up and down, adjust the descent mode until it is stable.
9. Once below 60km you can increase AoA to maximum of 13° (though 10° is safer) for more crossrange. Adjust pitch and yaw accordingly.
10. Keep this attitude until you are below Mach 1, after which you can flip around. Ensure you disabled descent mode, undelpoyed the flaps, and set the authority limiter back to 0, you may need to transfer all remaining fuel to the body if it's not flipping all the way around.
11. Land with style.

Happy flying!

( Image courtesy of: Internet Archive )