VSKYLABS Scheibe SF-25C Falke Belly Gear
VSKYLABS Scheibe SF-25C Falke Belly Gear: Manual motor-glider controls motivate reversible stick loading.
Aircraft and simulator scope
- VSKYLABS Scheibe SF-25C Falke Belly Gear · VSKYLABS · X-Plane 12 · Add-on starting point
The simulator model and controls
The SF-25 Falke combines a two-seat cockpit with a low wing and a fixed tractor propeller. Its design allows powered departures followed by soaring flight, with wing spoilers controlling the descent.
This profile selects VSKYLABS Scheibe SF-25C Falke Belly Gear for X-Plane 12.
How this profile feels
Manual motor-glider controls motivate reversible stick loading. Spring resistance builds with the selected airspeed response. A separate aerodynamic term adds speed-dependent control load.
The elevator tab supplies pitch trim; spoiler-end braking has separate source scope. Valid trim provides the configured pressure relief. Autopilot following is off.
Controls and trim
The SF25 motor glider has mechanical elevator-tab trim, a Limbach engine and wing spoilers. Its developer uses a separate parking-brake control, while real-aircraft material describes braking at the end of spoiler travel.
The selected implementation
The SF-25C has a Limbach L2000, fixed-pitch propeller, mechanical elevator-tab trim and wing spoilers. VSKYLABS uses a separate parking-brake lever instead of the real aircraft’s spoiler-end-travel brake.
About the values
The gains are normalized profile settings. They describe the chosen effect balance; hand force depends on the device and its output limits. IAS references are tuning values rather than operating limits. Physical acceptance of this revision remains pending.
Documentary review and sources
These decisions describe the documentary basis and remaining gaps for this revision. Aircraft documentation and a starting setting describe different kinds of evidence.
Aircraft and variant
InheritedThis profile selects VSKYLABS Scheibe SF-25C Falke Belly Gear for X-Plane 12.
Flight controls
InheritedThe SF25 motor glider has mechanical elevator-tab trim, a Limbach engine and wing spoilers. Its developer uses a separate parking-brake control, while real-aircraft material describes braking at the end of spoiler travel.
Trim
InheritedThe elevator tab supplies pitch trim; spoiler-end braking has separate source scope. Pitch authority 0.3 provides load relief and permitted centre movement; roll authority is 0.
Autopilot and stability
InheritedAutopilot following is off; the configured spring and load retain the hardware feel.
Equipment
InheritedThe SF-25C has a Limbach L2000, fixed-pitch propeller, mechanical elevator-tab trim and wing spoilers. VSKYLABS uses a separate parking-brake lever instead of the real aircraft’s spoiler-end-travel brake.
Speeds and limits
InheritedThe indicated-speed references set the profile response scale; they are separate from aircraft operating limits.
Simulator integration
InheritedThe profile targets xplane12. Add-on-specific controls use only the supported references configured by this profile.
Force-feedback settings
InheritedThe settings define the profile’s effect balance. Device output limits affect physical hand force.
Starting settings and their rationale
These configured values are starting estimates. The explanations describe what each setting controls; physical validation appears separately below.
| Setting | Starting value | What it controls and why |
|---|---|---|
| Spring strength | Starting value0.64 | What it controls and whyManual motor-glider controls motivate reversible stick loading. The baseline spring is 0.64. Its low-speed blend reaches baseline strength at 45 KIAS. |
| Master force gain | Starting value0.85 | What it controls and whyScales overall profile strength while preserving effect balance, subject to device and output limits. |
| Profile force gain | Starting value1 | What it controls and whyThe aerodynamic-load gain is 1 with an indicated-speed reference of 70 KIAS. This supplies speed-dependent loading alongside the spring. |
| Force tuning speed/reference | Starting value70 kt | What it controls and whySets the IAS reference for aerodynamic loading. It is an estimate, not published cruise TAS or a flight limit. |
| Spring response reference speed | Starting value45 kt | What it controls and whySets the IAS where the low-speed blend reaches baseline strength; high-speed stiffening also uses it. |
| Aileron force scale | Starting value0.66 | What it controls and whyRoll and pitch aerodynamic scales are 0.66 and 0.82, respectively. They set the aerodynamic axis balance. No custom spring-travel curve is enabled. |
| Elevator force scale | Starting value0.82 | What it controls and whyScales pitch aerodynamic loading; pitch spring travel and trim responses are separate settings. |
| Trim feel | Starting valueDisabled | What it controls and whyRetained for compatibility and group membership. Trim relief, rather than this flag, controls centre movement. |
| Trim relief | Starting valueEnabled | What it controls and whyAllows trim relief with supported control law and valid telemetry. Axis authorities set its amount. |
| Autopilot follow | Starting valueDisabled | What it controls and whyAutopilot following is off; the configured spring and load retain the hardware feel. |
| Autopilot neutral hold | Starting valueDisabled | What it controls and whyPermits centering hold during a supported AP state, separate from following a moving target. |
| Output force limit | Starting value0.55 | What it controls and whyCaps directed-force output. Native spring effects and device limits remain separate. |
All 44 starting settings and their rationale
The settings define the profile’s effect balance. Device output limits affect physical hand force.
| Setting | Starting value | What it controls and why |
|---|---|---|
| Spring strength | Starting value0.64 | What it controls and whyManual motor-glider controls motivate reversible stick loading. The baseline spring is 0.64. Its low-speed blend reaches baseline strength at 45 KIAS. |
| Spring deadband | Starting value0.04 | What it controls and whySets travel around the centre before the baseline spring resists. Smaller values engage it sooner. |
| Profile force gain | Starting value1 | What it controls and whyThe aerodynamic-load gain is 1 with an indicated-speed reference of 70 KIAS. This supplies speed-dependent loading alongside the spring. |
| Master force gain | Starting value0.85 | What it controls and whyScales overall profile strength while preserving effect balance, subject to device and output limits. |
| QBlend Enabled | Starting valueEnabled | What it controls and whyAllows baseline spring strength to rise with indicated airspeed where the control law permits it. |
| QSpring Minimum Factor | Starting value0.55 | What it controls and whySets low-speed spring strength as a fraction of baseline when blending is enabled. One keeps full strength. |
| QSpring Start Knots | Starting value10 kt | What it controls and whySets the IAS where the low-speed spring blend starts rising. This is a feel threshold, not a flight limit. |
| Spring response reference speed | Starting value45 kt | What it controls and whySets the IAS where the low-speed blend reaches baseline strength; high-speed stiffening also uses it. |
| Force tuning speed/reference | Starting value70 kt | What it controls and whySets the IAS reference for aerodynamic loading. It is an estimate, not published cruise TAS or a flight limit. |
| Airspeed spring stiffening gain | Starting value0.3 | What it controls and whyThe high-speed spring-stiffening gain is 0.3. It strengthens the permitted spring response above 45 KIAS, with the squared-speed ratio capped at 5. |
| Airspeed spring stiffening limit | Starting value5 | What it controls and whyLimits the squared airspeed ratio used for high-speed spring stiffening; it is not a device-force cap. |
| Aileron force scale | Starting value0.66 | What it controls and whyRoll and pitch aerodynamic scales are 0.66 and 0.82, respectively. They set the aerodynamic axis balance. No custom spring-travel curve is enabled. |
| Elevator force scale | Starting value0.82 | What it controls and whyScales pitch aerodynamic loading; pitch spring travel and trim responses are separate settings. |
| Output force limit | Starting value0.55 | What it controls and whyCaps directed-force output. Native spring effects and device limits remain separate. |
| Trim feel | Starting valueDisabled | What it controls and whyRetained for compatibility and group membership. Trim relief, rather than this flag, controls centre movement. |
| Trim relief | Starting valueEnabled | What it controls and whyAllows trim relief with supported control law and valid telemetry. Axis authorities set its amount. |
| Elevator Authority | Starting value0.3 | What it controls and whyThe elevator tab supplies pitch trim; spoiler-end braking has separate source scope. Pitch authority 0.3 provides load relief and permitted centre movement; roll authority is 0. |
| Aileron Authority | Starting value0 | What it controls and whyScales supported roll-trim relief and permitted centre movement. Zero removes roll response. |
| Force Trim Enabled | Starting valueDisabled | What it controls and whyEnables local force trim, separate from aircraft-owned trim and add-on integration qualification. |
| GLoad Enabled | Starting valueEnabled | What it controls and whyAllows load-factor changes to modify permitted spring laws. Passive fly-by-wire feel can suppress it. |
| Rate Damping Enabled | Starting valueEnabled | What it controls and whyEnables rate damping with the configured coefficients and control law. |
| Autopilot follow | Starting valueDisabled | What it controls and whyAutopilot following is off; the configured spring and load retain the hardware feel. |
| Autopilot follow authority | Starting value0.05 | What it controls and whySets admitted AP-follow gain, not a percentage of travel. Runtime ownership and input limits still apply. |
| Autopilot neutral hold | Starting valueDisabled | What it controls and whyPermits centering hold during a supported AP state, separate from following a moving target. |
| Autopilot neutral hold strength | Starting value0.6 | What it controls and whySets admitted AP neutral-hold strength; inactive while neutral hold is disabled. |
| Enabled | Starting valueEnabled | What it controls and whyEnables aerodynamic cues; each still needs nonzero strength and its simulator conditions. |
| Gain | Starting value0.4 | What it controls and whySets stall-buffet strength. Zero removes the cue without changing simulator stalls or warnings. |
| Gain | Starting value0 | What it controls and whySets high-Mach buffet strength; onset and full-strength thresholds are separate. |
| Gain | Starting value0 | What it controls and whySets flap buffet at the configured position and speed gates. Flap movement texture is separate. |
| Maximum flap index | Starting value1 | What it controls and whySets the final flap index for detent normalization. UP plus three detents uses maximum index3. |
| Minimum flap index | Starting value1 | What it controls and whySets the first flap detent that admits buffet; this is a handle index, not degrees. |
| Gain | Starting value0 | What it controls and whySets gear aerodynamic buffet; movement and ground-contact cues are separate. |
| Shaker Enabled | Starting valueDisabled | What it controls and whyPermits shaker at supported warning conditions; the switch does not establish aircraft equipment. |
| Stick shaker amplitude | Starting value0.5 | What it controls and whySets triggered shaker strength; inactive while the shaker feature is disabled. |
| Enabled | Starting valueEnabled | What it controls and whyEnables ground effects; each still needs its own strength and contact or motion telemetry. |
| Gain | Starting value0.3 | What it controls and whySets rolling texture strength, modified by speed, surface and undercarriage configuration. |
| Gain | Starting value0.3 | What it controls and whySets gear-bump texture during ground motion, separate from touchdown impact. |
| Gain | Starting value0.5 | What it controls and whySets landing-impact strength; landing telemetry and response shape determine the pulse. |
| Gain | Starting value0 | What it controls and whySets reverse-thrust vibration with valid reverser and engine conditions. Zero removes the cue. |
| Enabled | Starting valueEnabled | What it controls and whyEnables engine cues with nonzero settings and valid running-engine telemetry. |
| Gain | Starting value0.12 | What it controls and whySets estimated engine vibration using configured telemetry and response, not measured cockpit vibration. |
| Enabled | Starting valueEnabled | What it controls and whyEnables accessory cues with configured strengths and observed accessory movement. |
| Gain | Starting value0 | What it controls and whySets texture from observed flap movement; a command without movement does not establish the cue. |
| Gain | Starting value0 | What it controls and whySets texture from observed gear movement, separate from aerodynamic and touchdown effects. |
Limits and open questions
- Developer uses a separate variable parking-brake lever, unlike the real aircraft spoiler-end-travel wheel brake. Generic brake force disabled until readback is qualified. PDF26 publishes190km/h max and150km/h manoeuvring; those are not force stops.
- Physical and installed-aircraft acceptance deferred. Force values and indicated-speed reference are estimates.
- No unqualified AP following, dynamic configuration recognition, trim-actuator demand or add-on failure integration.
- 2026-10-11 installed-package documentary review: Installed Belly title identifies belly-gear variant; add exact observed title and exclude Dragger/tail-dragger tokens to avoid choosing belly profile for tailwheel.
- Conventional motor-glider controls and spoiler lever; existing manual feel retained. Spoiler-end-travel real-aircraft wheel brake is not assumed to be simulator brake readback.
- Retained estimated trim relief; no custom trim-actuator output or configuration-switched neutral has been qualified.
- No qualified add-on AP servo demand; existing AP follow and neutral hold remain disabled.
- Limbach2000L belly gear variant; developer lists belly and tailwheel separately. Existing generic brake cue stays disabled pending separate parking-brake readback.
- Current revision changes metadata/matching only. Force modules preserved exactly; no simulator, hardware or new telemetry acceptance in this review.
Physical validation
No physical force validation is recorded in this public catalogue for this revision. Documentary review and software checks do not establish how a particular device feels.