Start here
A few places to begin, from the aircraft’s story to the people who fly it.
Meet the aircraft
René Dorand’s G.20 was an experimental helicopter developed around coaxial rotors and two Renault engines. The prototype survived the interruption of the Second World War and reached ground testing, but did not fly. VSKYLABS’ Dorand D20 is a released freeware interpretation for X-Plane 12. It explores how the unusual design might have behaved, so the simulator’s flight characteristics are explicitly conceptual.
Aircraft background
VSKYLABS · Read more ↗A chance to explore an unflown design
The developer explains that the historical Dorand coaxial prototype underwent ground testing but never flew. Its X-Plane project therefore explores a possible flying interpretation rather than reproducing measured flight behaviour.
VSKYLABS Dorand D.20 / G.20 interpretation · X-Plane 12
VSKYLABS · Read more ↗Into the cockpit
YouTube Fly X-Plane · 32 min ·
Perth WA | X-World Pro | VSkyLabs Dorand D20
A VSKYLABS Dorand simulator flight over Perth at dusk in X-Plane.
Simulator · VSKYLABS Dorand D.20 · X-Plane
Watch on YouTube ↗Preview images are served by AirframeDB. Videos open on YouTube only when you choose to watch.
Meet Dorand G.20
René Dorand’s G.20 was an experimental helicopter developed around coaxial rotors and two Renault engines. The prototype survived the interruption of the Second World War and reached ground testing, but did not fly.
VSKYLABS’ Dorand D20 is a released freeware interpretation for X-Plane 12. It explores how the unusual design might have behaved, so the simulator’s flight characteristics are explicitly conceptual.
Dorand G.20
Société Française du Gyroplane → · Explore the family →
Dorand G.20
VSKYLABS · VSKYLABS Aerospace Simulations Aircraft Center: VSKYLABS 'Test-Pilot': Dorand D.20 ↗Dorand D20 simulated interpretation
VSKYLABS · VSKYLABS Aerospace Simulations Aircraft Center: VSKYLABS 'Test-Pilot': Dorand D.20 ↗VSKYLABS · X-Plane 12 →Aircraft type designators
A model-specific ICAO or FAA designator has not been confirmed in the references reviewed for this aircraft.
History & design
A naval helicopter interrupted by war
René Dorand’s G.20 was a French Navy-commissioned helicopter project of the late 1930s. According to the developer’s historical account, construction continued across the disruption of the Second World War and the sole prototype was completed in 1947.
VSKYLABS · VSKYLABS Aerospace Simulations Aircraft Center: VSKYLABS 'Test-Pilot': Dorand D.20 ↗Dorand G.20 historical prototype; VSKYLABS D.20 interpretation
An aircraft without a flight-test record
The prototype reached ground testing but never flew. VSKYLABS’ D.20, introduced in 2026, is consequently a functional interpretation of the unusual design rather than a reproduction of measured flight handling.
VSKYLABS · VSKYLABS Aerospace Simulations Aircraft Center: VSKYLABS 'Test-Pilot': Dorand D.20 ↗Dorand G.20 historical prototype; VSKYLABS D.20 interpretation
Systems & details
Two rotors of different diameters
The small vertical separation of the coaxial rotors led to unequal rotor diameters. Their opposite rotation is a defining part of the design. Any handling explanation for the simulator must retain the distinction between that documented arrangement and the unknown behavior of the unflown prototype.
In your simulator
Systems, equipment and documentation for each developer’s aircraft.
X-Plane 12Dorand D20
VSKYLABS · Released
Dorand D20
VSKYLABS · Released
Manuals & resources
Find your next read
Choose a topic for a short introduction and a link to the original source. Simulator references identify the developer and edition they cover.
Simulator documentation
A chance to explore an unflown designVSKYLABS Dorand D.20 / G.20 interpretation · X-Plane 12
The developer explains that the historical Dorand coaxial prototype underwent ground testing but never flew. Its X-Plane project therefore explores a possible flying interpretation rather than reproducing measured flight behaviour.
Project background and simulation scope
VSKYLABS · Read the source ↗Released product and variantsDorand D20 · VSKYLABS · X-Plane 12
This freeware release is a functional interpretation of the Dorand G.20, which never flew. The simulated flying qualities are conceptual and are not presented as measured performance from the real prototype.
Official developer / designated-store reference · checked 2026-09-14
VSKYLABS · Read the source ↗Read the original documentation from the people who created it. Manuals open on their publisher’s website.
Developer documentation
VSKYLABS Aerospace Simulations Aircraft Center: VSKYLABS 'Test-Pilot': Dorand D.20VSKYLABS · Official developer / designated-store reference · checked 2026-09-14 VSKYLABS Dorand G.20 - Freeware Experimental Coaxial Helicopter for X-Plane Flight SimulatorVSKYLABS · Official developer / designated-store reference · checked 2026-09-14Built-in force-feedback profiles
Read the documentary basis, editable starting settings and remaining questions for the aircraft you fly. Each explanation refers to the exact profile revision shown.
Catalogue programme-20261022-v1 · 1 profile choice
VSKYLABS Dorand D.20
VSKYLABS · Free and Pro · Revision 3 · Inherited starting point
X-Plane 12
VSKYLABS Dorand D.20: Nominal cyclic centering accompanies a simulator interpretation of an unflown prototype.
VSKYLABS Dorand D.20
VSKYLABS Dorand D.20: Nominal cyclic centering accompanies a simulator interpretation of an unflown prototype.
Aircraft and simulator scope
- VSKYLABS Dorand D.20 · VSKYLABS · X-Plane 12 · Add-on starting point
The simulator model and controls
René Dorand’s G.20 was an experimental helicopter developed around coaxial rotors and two Renault engines. The prototype survived the interruption of the Second World War and reached ground testing, but did not fly.
This starting point selects VSKYLABS Dorand D.20. Its aircraft-level settings do not select a particular developer’s custom systems.
How this profile feels
Nominal cyclic centering accompanies a simulator interpretation of an unflown prototype. The spring stays independent of airspeed. Directed aerodynamic loading is omitted. Cyclic damping adds resistance to hardware motion.
The selected spring centre is independent of any unestablished real-aircraft trim mechanism. Local force trim is off. Autopilot following is off.
Controls and trim
The Dorand G.20 is a coaxial helicopter prototype that never flew. The developer explicitly describes basic conceptual dynamics because its real flight characteristics were never established. Two contra-rotating, three-bladed rotors and Renault engines provide the documented configuration around that interpretation.
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 starting point selects VSKYLABS Dorand D.20. Its aircraft-level settings do not select a particular developer’s custom systems.
Flight controls
InheritedThe Dorand G.20 is a coaxial helicopter prototype that never flew. The developer explicitly describes basic conceptual dynamics because its real flight characteristics were never established. Two contra-rotating, three-bladed rotors and Renault engines provide the documented configuration around that interpretation.
Trim
InheritedThe selected spring centre is independent of any unestablished real-aircraft trim mechanism. Local force trim is off. Autopilot following is off.
Autopilot and stability
InheritedAutopilot following is off; the configured spring and load retain the hardware feel.
Equipment
InheritedGear, flap and ground cues follow the selected settings and available simulator-reported states.
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 value0.1 | What it controls and whyNominal cyclic centering accompanies a simulator interpretation of an unflown prototype. The baseline spring is 0.1. Low-speed spring blending is off. |
| Master force gain | Starting value0.65 | What it controls and whyScales overall profile strength while preserving effect balance, subject to device and output limits. |
| Profile force gain | Starting value0 | What it controls and whyThe 0 gain omits sustained directed airspeed loading. Spring resistance remains independent. |
| 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 value50.0 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 value1 | What it controls and whyRoll and pitch aerodynamic scales are 1 and 0.82, respectively. These stored weights do not create directed aerodynamic loading while that term is inactive. 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 valueDisabled | 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 value0.1 | What it controls and whyNominal cyclic centering accompanies a simulator interpretation of an unflown prototype. The baseline spring is 0.1. Low-speed spring blending is off. |
| Spring deadband | Starting value0.02 | What it controls and whySets travel around the centre before the baseline spring resists. Smaller values engage it sooner. |
| Profile force gain | Starting value0 | What it controls and whyThe 0 gain omits sustained directed airspeed loading. Spring resistance remains independent. |
| Master force gain | Starting value0.65 | What it controls and whyScales overall profile strength while preserving effect balance, subject to device and output limits. |
| QBlend Enabled | Starting valueDisabled | What it controls and whyAllows baseline spring strength to rise with indicated airspeed where the control law permits it. |
| QSpring Minimum Factor | Starting value1 | 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 value14.0 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 value50.0 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 | What it controls and whyAdds permitted spring resistance above the full-blend speed. Zero removes this high-speed increase. |
| 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 value1 | What it controls and whyRoll and pitch aerodynamic scales are 1 and 0.82, respectively. These stored weights do not create directed aerodynamic loading while that term is inactive. 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 valueDisabled | What it controls and whyAllows trim relief with supported control law and valid telemetry. Axis authorities set its amount. |
| Elevator Authority | Starting value0 | What it controls and whyScales supported pitch-trim relief and permitted centre movement. Zero removes pitch response. |
| 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 whyThe selected spring centre is independent of any unestablished real-aircraft trim mechanism. Local force trim is off. The stored latch parameters are inactive; the profile does not supply a local hold-where-left neutral. |
| 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 valueDisabled | 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 | 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 | What it controls and whySets rolling texture strength, modified by speed, surface and undercarriage configuration. |
| Gain | Starting value0 | What it controls and whySets gear-bump texture during ground motion, separate from touchdown impact. |
| Gain | Starting value0.2 | 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 | 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 explicitly states real flight characteristics were never established. Generic ETL/VRS/helicopter bands do not establish coaxial-specific wake physics; conservative rotor-dependent effects disabled pending rotor telemetry interpretation.
- 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.
- Metadata identity repair only; force modules, matching and simulator scope unchanged.
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.
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