HoverDrive
Physics-based hover, flying and drone movement for pawns

Overview

HoverDrive is a movement component for pawns that are not characters: anything whose root is a physics body. It never moves the actor kinematically; every effect is a force or torque on the body, so collisions, ramps, impacts and stacking behave physically. All tuning values are accelerations (cm/s²) multiplied by the body's mass, so a 200 kg bike and a 20 t tank feel the same with the same settings.

• 1. Hover points: any number of spring-damper raycast thrusters, placed by socket or relative offset (four are generated automatically).
• 2. Hover Drive Pawn: physics hull, visual body, chase camera and default bindings; throttle, strafe, turn and lift functions.
• 3. Banking: visual roll into turns and pitch under acceleration, with limits.
• 4. Altitude hold and terrain following: configurable hover height, height range, maximum slope, flight altitude hold.
• 5. Flight mode: full 6-DOF drone / flyer control with stabilised hovering in place.
• 6. Boost: energy pool, drain, recharge delay and rate.
• 7. Drift and air brake: lateral grip control and drag multiplier.
• 8. Water and surfaces: hover over a dedicated liquid trace channel and per physical-surface rules.
• 9. Auto-level: PID roll / pitch stabilisation with strength settings.
• 10. Influence volumes: wind with gusts, lift and gravity scaling inside an area.
• 11. Thruster output per point (0-1) and events for VFX and audio, including landing impacts.
• 12. Grounded / airborne state with events and an air control factor.
• 13. Telemetry struct and getter.
• 14. Networking: server-authoritative input replication; physics on the server, movement replicated by the engine.
• 15. Debug view: console variable HoverDrive.Debug draws rays, forces and telemetry (non-shipping).

Requirements

Installation

1. Install HoverDrive from Fab into your engine, or copy the HoverDrive folder into your project's Plugins folder.
2. Enable HoverDrive in Edit > Plugins and restart the editor.
3. C++ only: add PublicDependencyModuleNames.Add("HoverDrive"); to your Build.cs.

Quick start

1. Create a Blueprint class from Hover Drive Pawn (or use the C++ class directly).
2. Optionally assign your craft's mesh to Body Mesh (reset its scale, which is set to fit the placeholder cube) and resize Hull (Box Extent) to fit it.
3. Set it as Default Pawn Class of your game mode, or place it in the level with Auto Possess Player = Player 0.
4. Press Play: W/S throttle, A/D turn, Q/E strafe, Space/Ctrl hover height, Shift boost, Alt drift, X air brake, T flight mode (then R/F pitch, Z/C roll). Gamepads work too (see Input reference).
5. Type HoverDrive.Debug 2 in the console to see rays, forces and live telemetry.

1. Hover points

Component UHoverDriveComponent — displayed as Hover Drive. Each hover point traces straight down from the craft (along its own down axis). When the trace finds a surface, the point pushes up along the craft's up axis with a spring-damper force: it carries its share of the weight exactly at the hover height, pushes harder when compressed and softer when extended, and damping removes bounce.

Per point: accel = share × g × (1 + Spring Stiffness × compression) − Spring Damping × share × vertical point speed, with compression = (height − distance) / height, applied at the thruster location.

Nodes: call Set Hover Points (empty = automatic corners), pure Get Hover Point Count, Get Point States, Get Point Location.

2. Hover Drive Pawn

Pawn AHoverDrivePawn — displayed as Hover Drive Pawn. Components:

Input functions (call, Blueprint and C++): Throttle, Strafe, Turn, Lift, Pitch, Roll (float -1..1), Boost, Drift, Air Brake (bool held), Toggle Flight Mode. pure Get Hover Drive returns the component.

Use Default Input Bindings (on) registers the HoverDrive_* axis and action mappings at runtime (no project input settings needed) and binds them. Turn it off when you use Enhanced Input or your own bindings and call the functions above instead.

3. Banking

Banking tilts only the Banking Target (the visual mesh), never the physics body, so it cannot disturb handling or collisions. The rest pose is the target's relative rotation at Begin Play (or when Set Banking Target is called).

pure Get Bank Rotation returns the current visual roll and pitch.

4. Altitude hold & terrain following

In hover mode the hover points keep the craft at Target Hover Height above whatever is below it, so it follows hills, ramps and loops. With Align To Ground the auto-level also tilts the craft to the average ground normal, and the drive pushes along the ground plane.

Nodes: call Set Target Hover Height, pure Get Target Hover Height.

5. Flight mode

EHoverDriveMode: Hover (ground effect) or Flight. In flight the drive cancels gravity, every input axis becomes a 6-DOF command and every axis without input is braked, so a released drone stops and hovers in place, level, at its altitude.

Nodes: call Set Mode, Toggle Flight Mode; pure Get Mode, Is Flying; event On Mode Changed (New Mode).

6. Boost & energy

Nodes: call Set Boost Input, Add Energy (server; pickups, pit lanes); pure Get Energy, Get Energy Ratio, Is Boosting; event On Boost Changed (Is Boosting), On Energy Depleted.

7. Drift & air brake

Hover craft have no tyres: Lateral Grip is what stops them sliding sideways. Drifting lowers it and sharpens turning; the air brake multiplies the drag.

Nodes: call Set Drift Input, Set Air Brake Input. Telemetry reports Drifting, Air Braking and the Lateral Speed (slide).

8. Water & surfaces

Two independent ways to hover over liquids and special ground:

Liquid trace channel

Create a trace channel in Project Settings > Collision (for example Liquid, default Ignore), make your water plane Block it and ignore everything else, then enable Trace Liquid Channel and pick it as Liquid Trace Channel. Hover craft now skim across the water while characters and props fall in. The nearer of the ground and liquid hits wins.

Physical surface rules

Surface Rules is an array of FHoverDriveSurfaceRule: Surface Type, Can Hover (false = the point looks through that surface as if it were air), Force Scale and Drag Scale. With Only Rule Surfaces on, the craft can hover only over surfaces listed with Can Hover (for example only over a Track or Water surface type). Surface types come from the physical material of the hit (Project Settings > Physics > Physical Surface).

9. Auto-level stabilisation

A PID controller on roll and pitch rotates the craft's up axis toward the target up (world up, or the ground normal when grounded with Align To Ground). Yaw is never touched by it. The output is an angular acceleration, independent of the body's inertia.

10. Influence volumes

Actor AHoverDriveInfluenceVolume — displayed as Hover Drive Influence Volume. A box area (scale or rotate the actor to shape it) that acts on every hover drive whose centre of mass is inside. Several volumes add up. They have no collision and cost one point-in-box test per craft per frame.

Volume nodes: pure Get Influence At, Get Weight At; call Set Extent; event On Hover Drive Entered / On Hover Drive Exited. Component nodes: pure Get Active Influence Volumes, Get Current Influence (combined FHoverDriveInfluence); event On Influence Volume Changed (Volume, Entered).

11. Thruster output & events

Every hover point reports its output as Thrust 0-1 (about 0.5 while hovering at rest, rising when compressed or climbing, 0 when out of range). In flight mode the thrusters also show the weight-carrying and climb command, so engines keep glowing in the air. Drive Thrust is the engine output 0-1 (1 = full throttle with boost).

12. Grounded & airborne

The craft is grounded while at least Min Grounded Points (1) hover points touch a valid surface. In flight mode a point counts as touching only within 1.2 × the hover height (landed or skimming).

13. Telemetry

pure Get Telemetry returns an FHoverDriveTelemetry snapshot for HUDs, audio, AI and analytics:

14. Networking

HoverDrive is server-authoritative:

1. The owning client writes its input locally and sends it with the unreliable server RPC ServerSetInput whenever it changes (at most Max Input Send Rate, 30 per second) and as a keep-alive every Input Keep Alive Interval (0.2 s). The server clamps every axis. Mode and hover-height changes use reliable RPCs.
2. The server simulates the physics, owns the energy, boost and mode, and replicates them (Energy, Boosting, Mode; target hover height and input to the other clients).
3. The engine's replicated movement (physics replication of the root body) moves every client's copy; the Hover Drive Pawn enables Replicates and Replicate Movement.
4. With Client Side Simulation (on), clients apply the same hover forces to their copy between corrections so motion stays smooth; the owning client uses its own input and the other clients the replicated input. Turn it off for a strictly server-driven body.

Events (Grounded, Landing Impact, Thrust, Mode, Boost, Influence) fire on every machine, so VFX and audio work on all clients. Get Input returns the input in effect on the calling machine.

15. Debugging

Console variable HoverDrive.Debug (development builds; nothing is drawn in shipping builds):

The per-component property Draw Debug shows level 2 for one craft without the console.

Input reference

Component input nodes: Set Throttle Input, Set Strafe Input, Set Yaw Input, Set Lift Input, Set Pitch Input, Set Roll Input (-1..1), Set Boost Input, Set Drift Input, Set Air Brake Input (held), Set Input (whole FHoverDriveInput, for AI or replays), Clear Input, Get Input. Default pawn bindings:

C++

#include "HoverDriveComponent.h"
#include "HoverDrivePawn.h"

// Drive any pawn that has a Hover Drive component
if (UHoverDriveComponent* Hover = FindComponentByClass<UHoverDriveComponent>())
{
    Hover->SetThrottleInput(1.f);
    Hover->SetYawInput(-0.4f);
    Hover->SetBoostInput(true);

    const FHoverDriveTelemetry T = Hover->GetTelemetry();
    UE_LOG(LogTemp, Log, TEXT("%.0f km/h, %.0f cm above ground"), T.SpeedKmh, T.AltitudeAboveGround);
}

// In your own physics pawn's constructor (HoverDrive is a UHoverDriveComponent* UPROPERTY)
HoverDrive = CreateDefaultSubobject<UHoverDriveComponent>(TEXT("HoverDrive"));
HoverDrive->HoverPoints.Add(FHoverDrivePoint(FVector( 120.f,  60.f, -30.f)));
HoverDrive->HoverPoints.Add(FHoverDrivePoint(FVector( 120.f, -60.f, -30.f)));
HoverDrive->HoverPoints.Add(FHoverDrivePoint(FVector(-120.f,   0.f, -30.f)));
HoverDrive->BankingTarget = VisualMesh;

// React to landings (BeginPlay); HandleLanding is a UFUNCTION(float ImpactSpeed, FVector Location)
HoverDrive->OnLandingImpact.AddDynamic(this, &AMyCraft::HandleLanding);

Classes: UHoverDriveComponent, AHoverDrivePawn, AHoverDriveInfluenceVolume. Types: FHoverDrivePoint, FHoverDrivePointState, FHoverDriveSurfaceRule, FHoverDriveInput, FHoverDriveInfluence, FHoverDriveTelemetry, EHoverDriveMode, EHoverDriveAltitudeHold.

Troubleshooting

Credits

© 2026 Alpha XP — alphaxp.net · Support: support@alphaxp.net. Built for Unreal Engine 4.27 and 5.8.