Approximately Up Hover Logic Circuits

Holding a vertical lever at exactly the right notch to hover is classic Approximately Up comedy — until you need both hands for RCS during a Moon Landing. Hover logic automates altitude by reading vertical velocity and feeding corrective thrust through a small PD controller built from logic blocks. No altitude meter required; a velocity meter pointing downward is enough.

This guide builds the circuit step-by-step. You need working Power and Data Routing, lifting thrusters on a flyable frame from Build Your First Ship, and basic Controls literacy (G garage, R fly, Mouse 3 reset).

Components checklist

Gather these before wiring:

Part	Role
Velocity meter	Reads vertical speed; enable directional mode, point down
Data router	Splits and routes sensor and logic signals
Accumulator	Integrates velocity error over time (I term helper in PD stack)
Remapper	Scales values into useful thrust range
Adder	Combines correction terms
Multiplier	Applies gain; tunes aggressiveness
NOT gate	Optional inversion for enable/disable paths
Switch	Master hover on/off
Lever (optional)	Target hover height or bias trim

All logic connections use data cables only. Thrusters still need power from your router.

Video guide

Circuit overview

Conceptually the hover loop does this every physics tick:

1. Velocity meter reports downward/upward speed
2. PD math compares velocity to target (zero for level hover)
3. Correction signal merges into thruster data input
4. Switch gates the signal off when you want manual control

Unlike Space Engineers gyro dampers, Approximately Up expects you to build the damper. The PD approach damps oscillation: proportional term reacts to current velocity; derivative/accumulator path reduces overshoot.

Step-by-step build

1. Mount the velocity meter

Place the velocity meter on your hull pointing downward. Enable directional mode in its settings so it reads vertical velocity relative to the ship, not arbitrary world axes. Wrong orientation makes the circuit fight itself — ship shakes, you blame thrusters, you rebuild the whole frame unnecessarily.

2. Router and accumulator

Run velocity meter output through a data router into an accumulator input. The accumulator tracks integrated error — when you sink, it builds correction; when you rise, it drains. This stabilizes hover against slow gravity drift on Earth and low Moon gravity.

3. Remapper and multiplier

Feed accumulator output into a remapper to scale values into 0..1 thrust band your thrusters expect. Follow with a multiplier to set gain. Start conservative — low multiplier = soft hover; high multiplier = snappy but oscillatory.

Tuning formula from community testing: compare ship total mass to total hover thrust, then scale with remapper constants. Use the Thrust Calculator for mass/thrust numbers instead of guessing. Example workflow: divide mass by available hover thrust, multiply by engine-specific scaling constants, then adjust multiplier until hover neither hunts nor sinks.

4. Adder and thruster merge

Use an adder to combine PD output with manual throttle if you want hybrid control — manual lever on one input, hover correction on the other. Output goes to lifting thruster data inputs (often through a data router splitting to four corner jets).

5. Switch enable line

Place a switch on an enable branch: switch ON passes hover correction; switch OFF leaves manual throttle only. Wire switch through a data router so you can flip hover from the cockpit without entering garage mode mid-flight.

Optional lever sets target bias — useful for creeping ascent during Missions Walkthrough cargo runs.

Earth test procedure

1. Garage (G) — verify velocity meter directional down
2. Fly (R) — manual throttle to ~10 meters
3. Flip hover switch ON — hands off lever
4. Ship should settle to stable altitude within a few seconds
5. If oscillating: lower multiplier; if sinking: raise remapper output or add thrust
6. Mouse 3 reset levers after tests

Practice on Earth before Moon Landing — lunar low gravity exposes over-tuned PD as slow bouncing forever.

Integration with RCS and missions

Hover logic holds altitude; RCS thrusters handle pitch/yaw/roll. Assign one crew member to hover switch and another to RCS in co-op — see Co-op Guide.

Ice cream freezer missions need stable hover near pads plus continuous cargo power — hover reduces crash risk; routing keeps freezers cold.

Common hover logic mistakes

Mistake	Result
Velocity meter not directional	Violent shaking
Correction on power port	No hover effect
Multiplier too high	Bounce oscillation
Multiplier too low	Slow sink into pad
Switch wired backwards	Hover always on/manual dead
Thruster underpowered	Logic correct, physics insufficient

Advanced extensions

After basic PD hover works, experiment with:

• Second remapper for altitude bias from a lever
• NOT gate to invert enable for fail-safe cutoffs
• Auto-braking helpers (separate tutorials) using trajectory meters

Check Tier List for logic block priorities when inventory is tight.

Related guides

• Power and Data Routing — data-only logic wiring rules
• Build Your First Ship — thruster layout hover pushes against
• Getting Started — when to add automation versus manual levers
• Planets Map — gravity varies by world in full release

Hover logic is the first time Approximately Up feels like engineering instead of lever babysitting. Build it once on Earth, copy the subassembly to every serious ship, and save RCS batteries for rotation where it matters.