BAK Zephyr - Duna VTOL spaceplane

[Guest]

Duna presents particular challenges for spaceplane design. The low gravity and thin atmosphere means that you need big wings, but once you have them, you tend to keep going forward until you drift down low enough and smack into a dune. In other words, landing can be a nerve-wracking process and it is hard to do it at all precisely. Similarly, take-off can be very dangerous as you need to build up a significant amount of speed to have enough lift to un-stick, and sufficiently flat areas for this aren't easy to find.

The Brikoleur Aerospace Kombine (BAK) Zephyr solves this problem with full (Duna) VTOL capability. It carries a full science payload, a retractable solar panel for orbital use, and has reasonable crew capacity. On-surface refuelling requires the Klaw; it has an inline docking port for in-orbit refuelling.

If precise positioning is not important, it's easiest and cheapest to make rocket-assisted short landings, where your hover rockets provide the lift your forward velocity doesn't. The same applies to take-offs.

Craft: https://kerbalx.com/Brikoleur/Zephyr

NOTE: Since the Zephyr is optimised for Duna, it is not able to even take off from Kerbin under its own power. If you want to play with it at KSC, replace the Terriers with Darts. It won't have the dV to reach orbit, but you should be able to land on the heliport at the top of the VAB.

Atmospheric entry and flight to destination

Set your Pe to around 10,000 m above the destination. Enter at a moderate pitch, ca. 30 degrees, and once Pe reaches the surface, control your precise landing spot with pitch (steeper = slower). Aim for a spot a few km before the target.

Approach

When approaching your target, slow down by making S curves or holding a steep pitch and climbing. Maintain a nose-up attitude, lower gear (which also opens the hover thruster bays), shut down the forward jets (Action 1), and start the hover jets (Action 2).

You should be able to get to about 100 m/s while maintaining normal aerodynamic flight.

Short landing

Maintain a nose-up attitude (10-20 degrees) and gradually apply throttle to control your descent rate. Once you're down to a safe touchdown speed (recommended 40 m/s or less), lower throttle, touch down, and brake to a halt.

Hover and vertical landing

Pitch up sharply and apply throttle to the hover jets to kill your horizontal speed, activate RCS. Use RCS retrograde if necessary. Then switch control to up (Action 9), level out (use SAS Surface/Radial Out if necessary), control your altitude/descent rate with throttle and your horizontal vector with RCS; to move forward toggle the main jets on and off briefly (Action 1). Lower yourself to the surface by controlling throttle.

Short take-off

Activate both forward and hover thrusters (Action 1, Action 2), switch on RCS, apply full throttle, and pull up. Once you have enough forward speed, kill the hover thrusters (Action 2), retract gear and close the hover thruster bays, and fly yourself to orbit.

Vertical take-off

Activate hover thrusters (Action 2), set control point to up (Action 9), SAS to Surface/Radial out, RCS on. Then apply throttle to lift yourself off the surface. When at a sufficient altitude, activate forward thrusters (Action 1). When you have built sufficient speed, set SAS to normal mode, control forward (Action 8), RCS off, deactivate hover thrusters (Action 2), raise gear and close bays, and you're off.

 

 

Edited February 26, 2018 by Guest