Working Room · Radio, Power & Diagnostics

Electronics
Bench

This is where the invisible parts of an aircraft become understandable: radio links, receiver architecture, redundant power, servos, wiring, telemetry, programming and failure testing are treated as one system rather than a pile of boxes connected by hope.

The central question: If this fails, what do I lose?

Systems become physical

The wiring ends at real hardware.

The Electronics Bench follows every signal and power path through the installed aircraft. The photographs keep that work tied to the control linkage and the cockpit structure it must ultimately serve.

Carbon Cub control linkage and control surface detail — Control linkage at the aircraftProgramming and redundancy only matter when the mechanical path is sound.

Original instrument panel from Jon's L-4 restoration — Original L-4 instrument panelA documented aircraft interface preserved before restoration.

Architecture

Redundancy is not one thing.

Electronics design starts with consequences rather than product names. A propulsion failure should not automatically remove control. An accessory fault should not collapse the receiver bus. A single connector, battery, receiver path or programming change should not quietly become the point where the whole aircraft depends on one thing working perfectly.

RF-band diversity

Two frequency bands can improve link resilience when the transmitter and receiver system are designed to use them together. FrSky Tandem's simultaneous 2.4 GHz + 900 MHz capability is one example.

Receiver redundancy

More than one receiver path can reduce dependence on a single receiver or local antenna environment. Exact implementation belongs to the aircraft being built.

Power redundancy

Independent receiver-power paths protect flight controls from one battery, lead, connector or power-path failure.

Servo / control redundancy

Independent control surfaces or channels can reduce single-point failures, but this is not automatically created by having two receivers.

A system may have one kind of redundancy without the others. The Electronics Bench keeps those layers explicit.

FrSky / ETHOS

The question became larger than which transmitter feels nicest.

The giant-scale projects drove a requirement for RF diversity, telemetry, diagnostics, expandable receiver architecture and a programming environment that could support complex aircraft without turning the radio into a black box.

Earlier RadioMaster / EdgeTX / ELRS work remains valuable design history because it sharpened the redundancy questions. The present giant-scale ecosystem is FrSky Tandem X20R / ETHOS, while each aircraft still controls its own exact receiver, power, antenna, stabilization and failsafe implementation.

Current shared platform

FrSky Tandem X20R / ETHOS

What ownership does not prove

Owning the transmitter does not prove a specific receiver pair, antenna arrangement or stabilization system is installed in every aircraft.

Historical work still matters

Superseded receiver and RF studies are preserved when they explain how the current design questions were reached.

Learning ETHOS

Build confidence before complexity.

Navigation and model management

Learn screens, widgets, model creation and model selection.

Controls and outputs

Assign switches, verify the channel monitor and confirm direction before connecting a live propulsion system.

Receivers and sensors

Modes, logic and warnings

Add flight modes, logical switches, voice alerts and failsafe behavior only after the basic control path is understood.

Aircraft-specific validation

Prop removed. Control movement verified. Failsafe checked. Then repeat after every material programming change.

Power & distribution

Control should survive propulsion loss.

Flight-critical control

Receivers, power hub/distribution, control servos and required aircraft-allocated sensors.

Propulsion

Motor, ESC, propulsion batteries and propulsion-specific instrumentation.

Accessories

Lighting, cameras, recording systems and other non-critical loads unless an aircraft-specific safety decision says otherwise.

A telemetry connection between domains is not allowed to become a hidden power dependency.

Receiver power: Two batteries are useful only if the paths are genuinely independent. Redundancy is a claim until something is unplugged and the airplane keeps working.

Separate battery identity
Separate lead and connector path
Separate input where architecture supports it
Loaded-voltage observation
Single-path survival test
Clear warning when one path disappears

RB25S and distribution

The RB25S is part of the current giant-scale architecture work, but this room does not assign one physical installation to every aircraft. Aircraft-specific pages remain authoritative for whether a hub is allocated, mounted, wired, tested and released.

Receivers, antennas & servos

Physical diversity matters.

Two receivers mounted together with antennas bundled in the same orientation can share the same shielding, polarization and impact vulnerabilities. Final receiver pair and geometry remain aircraft-specific decisions.

Receiver installation

Separate useful antenna locations, avoid obvious shielding and high-current conductors, use useful polarization diversity, test in the finished aircraft and record final geometry.

Servo selection

Mechanical first. Electronics second. Load, geometry, speed, durability and linkage quality come before programming convenience.

Independent channels

Separate elevator, aileron or flap channels can improve adjustment, diagnosis and fault isolation when the aircraft design calls for them.

No brand assumptions

A load study may define required capability without locking a manufacturer or model.

Wiring standard

Every extra connection is another place to fail.

Purpose-made wiring reduces adapter chains, unsupported connectors and mystery junctions. The goal is a harness that can be inspected, understood and repaired.

Keep away from sharp edges and moving controls.
Separate high-current propulsion conductors where practical.
Use grommets, clamps and strain relief where needed.
Label both ends when serviceability benefits.
Protect wing-root connectors from partial engagement.
Document pinout and polarity.
Provide sensible service loops without loose coils.

Wing-root connections

A connector used every flying day deserves the same design attention as a component buried inside the fuselage: visible engagement, positive orientation, left/right identification, protected service loop, recorded pinout and continuity check after assembly.

Telemetry

Data selected for decisions, not decoration.

Telemetry earns its place when it answers an operational question. It is advisory and diagnostic; it is not primary flight authority.

Control health

Receiver-bus voltage, power-path state and RF/link information can reveal developing problems.

Energy

Voltage, current and capacity-used data can help explain propulsion demand and battery behavior when the final aircraft has the required interfaces.

Temperature

Motor, ESC, battery-bay or other temperatures are useful only after actual sensor location and calibration are known.

Flight data

GPS and pitot airspeed can support awareness, testing and post-flight analysis when allocated and calibrated.

Owned sensors vs installed sensors

The broader FrSky record proves ownership of GPS ADV, PAS70 ADV and PT100-class sensor capability. That does not automatically mean those devices are installed in the L-4, quarter-scale Cub or another aircraft.

owned → allocated to aircraft → physically installed → calibrated/tested → operationally used

Voice warnings

If everything talks, nothing sounds urgent. Highest priority belongs to control-link health, receiver-bus voltage and receiver-power/failover conditions; routine data can remain on demand or be spaced deliberately.

Stabilization & testing

Assistance must never hide an airplane problem.

Stabilization remains an aircraft-specific choice. Any implementation must be checked for sensor orientation, correction direction, gain, mode behavior, switch logic and failsafe interaction. It is never a substitute for correct CG, straight structure, free hinges, proper linkage geometry, sound control surfaces, basic trim or pilot control.

Individual components

Power inputs, hub/distribution, receivers, servos, sensors and switches checked separately.

Integrated system

Complete control architecture under simultaneous servo load while deliberate failures are introduced.

Installed aircraft

Range, orientation, interference, motor-running environment, wing assembly and service access tested in the real airframe.

Deliberate failover

Unplug what the system claims it can lose: Receiver Battery A, Receiver Battery B, primary receiver path, redundant receiver path, selected sensor, confirmed non-critical accessory branch and propulsion interaction. Ask: did control continue, did the correct warning appear, and did the fault propagate?

Range and interference

Final range work is repeated with the aircraft in multiple orientations and, where safe, with propulsion operating. Investigate link-quality degradation, resets, jitter, telemetry dropout, sensor instability, voltage dips, orientation sensitivity and abnormal temperature rise.

Configuration control

A safe setup can become unsafe after one undocumented change.

Firmware, receiver settings, wiring, endpoints, gains, battery assignments, warnings and failsafe are configuration-controlled. Material changes trigger the relevant tests again. The as-flown record belongs at the end of the evidence chain, not the beginning of the design process.