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ES-107 SKYLON

ES-107 SKYLON is a versatile medium/heavy lift SSTO spaceplane. It can deliver maximum 70t cargo or 32 passengers to LKO. It’s based on the REL Skylon proposal, but not meant to be a replica.

Pure stock, no mods, no DLCs. 161 parts (spaceplane itself), 314 parts (total, with 4 modules), root part is the front Mk3-3.75m adapter.
See screenshots and Design Notes for notes on custom flag.

- Ah…that elegant silhouette.
- "3.75m cargo bay" made with flags.
- 200m/s dV @ 85x85km LKO with maximum (70t) payload, 900m/s with low density payload.
- Balanced and almost constant CoM regardless of fuel consumption, decent maneuverability and stability during the entire mission. No need to transfer fuel.
- CoM sits near the center of cargo section for easy payload arrangement.
- Includes 4 optional payload modules.
- Atmosphere-skipping and good gliding capability.

- It’s another experiment on unconventional cargo bay designs, and my first step into the world of flag building.
- While the pure white placeholder texture is acceptable for me, the flags still look a lot nicer with stock background texture. It’s simple to have it: get a fully transparent picture, name it "empty" (empty.png) and place it in your KSP Flags folder. I provided a ready-made empty flag HERE.
- The Skylon looks like a vehicle with not much lift at low speed. It requires a 5.5km long runway to achieve takeoff speed, while in KSC we only have 2.5km. Even though I’ve added as many wing surfaces as I can accept to be reasonable, it still requires most of the runway PLUS ~10deg AoA to generate enough lift. I have to put a tail wheel to prevent from tail strike - in fact, the tail wheel has to touch the ground for the spaceplane to lift off.
- The Skylon C1 design features an indented fuselage (peanut shape) common to supersonic aircraft (area rule, wave drag, all those fancy stuff), which is cancelled in the newer Skylon D1 configuration, because the saved structural weight and larger cargo bay combined is considered more beneficial than the supersonic drag reduction.

Ascent: 5°-10°-Prograde
- Stage to start engines, gently rotate at 120m/s and let the tail wheel touch the ground. For heavy payload, pull up near the end of the runway, and keep pulling up until ~160m/s to achieve stable cruise flight.
- Keep aiming at 5 degrees pitch.
- It should accelerate to 400m/s at 1-2km altitude. Keep 5 degrees pitch until 10km altitude.
- At 10km, stay away from pitch control, let it pitch up to 10 degrees while accelerating, then keep this pitch.
- When speed hardly increases (~1420m/s @ 20km), press [1] to switch RAPIERs mode, [2] to fire vacuum engine. Keep aiming at 10 degrees pitch.
- Push AP to desired value, shut down engines, lock prograde and coast till circularization. 85km AP should be 6 minutes away.
- Use only the vacuum engine for orbital maneuvers. If you shut down the RAPIERs when AP reaches 50-60km and fire only the vacuum engine, an additional 50-100m/s dV saving can be achieved.

Descent: 40km PE Aerobraking Reentry
- Burn PE to 40km above landing zone.
- Lock radial-out to aerobrake.
- When estimated impact point reaches landing zone, reduce AoA to 0-45°. 30°is good for maintaining impact point while effectively slowing down; 20°AoA pushes it further, >30°AoA draws it closer, 0°AoA corresponds a near-ballistic reentry path.
- Use RAPIERs in air-breathing mode when necessary.
- MouseAimFlight mod is highly recommended for final approach and landing.

Wish you enjoy and happy landings!