KerbalX

Description

The latest and greatest SSTO that I’ve made, the LX-300 Crescendo is a super-heavy SSTO designed with large, bulky payloads in mind. Although it doesn’t fly perfectly and doesn’t have a huge range of capabilities, it gets payload to orbit and that’s what matters the most.

Attaching Payload

When loading payload into the craft, make sure the CoM is roughly aligned with the drain ports on the insides of the side engines. Doesn’t have to be perfect, as the test payload demonstrates.

Build the fairing from the front and attach it to the fairing at the rear when you’re finished.

How to Fly

NOTE: This will assume that you have a payload near max capacity (280-315 tons) in the fairing.

Takeoff

Turn SAS on. Start the rapiers at half throttle (they will flame out otherwise). When you reach 20-30 m/s on the runway, it is safe to throttle all the way up. At around 90 m/s, start pitching up, minding the tail. Fly off the end of the runway; the craft may drop close to the water, but maintaining an angle of attack of around 7 degrees will keep you safe.

Ascent

Hold around 5-7 degrees angle of attack and try to reach 400 m/s below 1 km. After that, let the craft climb on its own until around 8.5-9 km. At this point, begin pitching down to gain speed in the upper atmosphere. Try not to fly completely flat, or you will lose wing parts to overheating. Attempt to reach 1500-1550 m/s by 20 km. At 20 km, switch Rapiers to closed cycle and turn off the intakes. Burn out apoapsis to about 105 km and cut the engines. Hold prograde and coast to space; once in space, you’ll have a good five minutes or so to plan your circularization burn. Use the RCS when in space. After circularizing, you should have around 200-500 dV left (1000+ without payload).

Reentry and Landing

Drain fuel tanks if needed. Deorbit by putting your periapsis at about 35km. Hit action group 9 to control from the angled docking port, and hold prograde while reentering until you’re flying at about 1000 m/s or so. Switch back to the cockpit with action group 0.
Be warned- Crescendo loses speed VERY SLOWLY when empty and can glide for ages without the need of the engines. I have not attempted a landing back at the KSC as I overshot it by almost a quarter of the planet every time.
Land very carefully at around 60-75 m/s with the brakes on - don’t flare aggressively as you will smack the tail into the ground! You want the wheels to touch the ground at an angle close to zero. Deploy the drogue chutes if necessary.

Notes

• Sometimes the craft will roll to the left a bit early in the flight. I have no idea why it does this but it’s more effort than it’s worth to correct it mid-flight
• If you’re draining fuel to rebalance the craft, stop draining it when your dV drops to about 1000 m/s in space without payload or fairing. I haven’t tested reentry beyond this and it may be unstable.
• Seriously, this craft is stupidly good at gliding. It does not lose speed or altitude like, at all. Even with the gear down the whole time. You will almost certainly overshoot on your first time flying.

Parts: 240
Root Part: mk2Cockpit.Inline
Building: SPH
Version: 1.12.5
Requires Making History DLC