Flight Operations

Family-level flight procedures. Aircraft-specific values (speeds, altitudes, wind limits, reserves) are in Part B; values shown as [TBD] here are per-aircraft and tracked on the Open Questions page.

1. Pre-flight inspection (before powering)

Pre-flight inspection must NEVER be conducted with the aircraft powered.

Inspect every surface for dents, cracks or delamination; assess against the damage-tolerance criteria and crack-length repair ladder (3 / 15 / 50 mm — see Maintenance → Damage tolerance & repair); reject a crack in a load path, one ≥ 3 mm unrepaired, or one that has grown. Then confirm:

• Propeller/vanes — free of damage; folding prop (where fitted) seats cleanly; TVC vanes and fins undamaged and free.
• Structure & fold joints — wing/tail attachment and any fold latches engaged, not strained.
• Propulsion mechanical — motor-mount fasteners secure (paint-witness intact), prop retention tight, motor spins freely with no rough spots.
• Pitot (where fitted) — free of blockage, cover installed during inspection. (Note: the EP450 demonstrator has no airspeed sensor — see its aircraft data.)
• Battery — no swelling/leak/heat; connectors clean; voltage in range for state of charge.
• Control surfaces / servos — free movement, minimal play, secure horns and push-rods.
• Antennas & wiring — secure, oriented per spec, no chafing.

Complete the printable pre-flight checklist (RFD-QRH-001) and record the result.

2. Powering & connecting

1. With the aircraft positioned for take-off on a prepared vertical launch surface and pitot cover in place (where fitted), confirm the GCS is open, telemetry is on the correct port/baud, and Connect is ready.
2. Connect one battery lead via the anti-spark connector — the autopilot boots (start-up tone), motors chirp, control surfaces sweep their range.
3. Connect the remaining battery lead(s) directly.
4. On the GCS press Connect; parameters load.
5. Secure all hatches; keep the aircraft still while sensors initialise.

Confirm before proceeding: autopilot “initialised” tone · 3D GPS fix — the autopilot requires ≥ 6 satellites (PX4 EKF2_REQ_NSATS); RFD recommends waiting for ≥ 10 before take-off · EKF white · heading and attitude stable · battery nominal · aircraft position correct on the map.

Home is set where the aircraft is powered up — this is the default RTL point. Verify it is the intended launch point before take-off.

Pre-flight calibration (pitot-equipped aircraft): on the Actions tab run PREFLIGHT_CALIBRATION; airspeed should read ~zero. Remove the pitot cover and confirm a brief rise then return to ~zero.

3. Arming

1. Maintain a safe stand-off from the aircraft/tube (≥ 15 m).
2. Confirm flight mode is hover (Q-) mode; throttle at zero.
3. Confirm the correct mission is uploaded and read back.
4. Turn the arm switch to ARM — motor(s) spool to idle.

Danger

Do NOT arm in AUTO mode. If a wrong waypoint is selected the aircraft will immediately fly to it, possibly in an unsafe configuration. Arm in hover mode, then select AUTO.

4. Take-off & forward transition

1. With the correct mission uploaded, arm in hover mode (zero throttle).
2. Select waypoint 1 (VTOL_TAKEOFF), then select AUTO — the aircraft commences vertical take-off.
3. Take off already aligned with the intended outbound bearing (the tail-sitter cannot slew a large heading quickly in hover; the single-motor EP450 especially).
4. Monitor altitude, pitch, roll and rates during ascent; abort to hover for a manual landing if anything is abnormal.

Forward transition (pitch-over). Autopilot-managed. The RFD forward transition is tuned to be near-flat (small altitude change) and to hand off at the design cruise speed. Monitor: altitude (small excursion), airspeed (must reach cruise before the wing is fully load-bearing), and attitude. Be ready to revert to hover if the transition does not complete cleanly within 7 s.

5. Cruise

Monitor the waypoint sequence, EKF, battery and behaviour. Fly at the design best-range speed for endurance (per-aircraft). If anomalies appear, take control in a stabilised forward mode (FBWB); if that fails, escalate to FBWA (fly actively — FBWA holds neither altitude nor airspeed).

No airspeed sensor (EP450 demonstrator): cruise speed is set open-loop by throttle and drifts with wind/weight — watch ground speed and keep margin above stall. See its aircraft data.

6. Back (reverse) transition & landing

Back transition (pitch-up). Before it, the aircraft should be straight and level. The autopilot pitches up and decelerates, trading cruise kinetic energy for a modest altitude gain (a “balloon”) — this is inherent to a tail-sitter and cannot be fully removed; allow ≈ 20 m of vertical clearance above the intended hover point. Monitor pitch, airspeed, altitude and battery; be ready to revert to hover if recovery does not stabilise.

Vertical landing. The aircraft positions above the landing point and descends vertically. Take control in hover mode if the landing point is wrong or the descent rate is incorrect. Reserve enough energy for the descent (see the landing-energy note in Battery Management).

Disarming. The aircraft auto-disarms 2 s after landing is detected (PX4 COM_DISARM_LAND default). Approach only once the HUD shows DISARMED; manually disarm from the GCS if auto-disarm fails.

7. In-flight monitoring — watch / normal / act

What to monitor in each phase, what normal looks like, and when to act:

Phase	Watch	Normal	Act
VTOL climb	Attitude, rates, drift from pad	Steady near-vertical climb, small excursions	Oscillation, growing drift, or abnormal noise → abort to hover and land
Forward transition	Pitch-over, speed build, altitude	Near-flat (small altitude change), hands off at cruise speed	Fails to complete cleanly, or sinks after hand-off → revert to hover
Cruise	Ground speed vs plan, altitude, battery vs plan, link quality, EKF	Steady speed and altitude, battery tracking the mission plan	Speed sagging toward minimum, battery below plan, or anomaly → shorten the mission / take FBWB
Back transition	Entry alignment, the balloon, clear volume overhead	Straight-and-level entry; a ~20 m zoom climb as speed converts to altitude	Only initiate with the overhead volume clear — once the pitch-up starts, ride it out; do not fight it
Vertical descent / landing	Descent rate, drift, battery	Steady descent onto the pad (demonstrated accuracy ~0.5 m)	Wrong point or wrong rate → take hover control. 🚫 Do not attempt a go-around after a low-battery warning

8. Failsafes & emergency procedures

General principle: always try to recover the aircraft safely. First option is RTL; if RTL is unsafe (launch point occupied/compromised), divert to a pre-surveyed alternate within visual line of sight. “Maintain aircraft control — analyse the situation — take appropriate action.” Aircraft can be replaced; people cannot.

Failsafe reference (PX4)

What the aircraft does automatically, and what the crew does. Values are the PX4 defaults for the RFD configuration; per-aircraft tuning is recorded in the aircraft’s configuration reference.

Condition	Trigger	Aircraft behaviour	Crew action
RC link lost	0.5 s without RC (COM_RC_LOSS_T)	Auto-RTL (NAV_RCL_ACT = Return)	Monitor on telemetry; re-establish RC; be ready to take over on regain
Telemetry (GCS) link lost	10 s timer (COM_DL_LOSS_T)	No automatic action — crew-managed (NAV_DLL_ACT 0, as delivered); the mission continues; RC still commands. Operators may configure a datalink-loss action per the PX4 documentation	Keep the GCS running (link often returns); reposition/raise the antenna; use RC if action is needed
Battery low	15 % (BAT_LOW_THR)	Warning only — no automatic action (COM_LOW_BAT_ACT 0); the crew manages battery	Begin recovery now; land as soon as practical
Battery critical / emergency	7 % / 5 %	Warning escalates	Land immediately — do not attempt to complete the mission
EKF / estimator failure	EKF indicator orange/red	Position control degrades	FBWA (forward) or hover (vertical); fly to a safe site; land in hover, escalating to direct-throttle stabilised if hover misbehaves. Contact RFD before further flight
GPS lost	Fix lost in flight	Position hold degrades; hover will drift	Forward flight: FBWA and fly visually to the recovery area; hover: land promptly with manual corrections
Geofence breach	If configured (GF_ACTION)	Per the operator’s configured action	Confirm the aircraft’s response; take over if it does not recover

Caution

Battery is crew-managed on this platform. Automatic low-battery flight termination is not armed by default (voltage sags under hover load and false-triggers) — the warnings fire, but you fly the recovery. Plan reserves accordingly (see Battery Management).

Situational emergencies

• Standard RTL — terminates the mission and flies to the landing sequence. Monitor it like any auto mode; be ready to take manual control. 🚫 Do not use RTL while in hover configuration — land using hover mode instead.
• Bird/wildlife — if a bird tracks the aircraft, land as soon as possible; if aggressive, climb above and clear laterally, then land with forward speed (avoid vortex-ring state).
• Deteriorating weather — manoeuvre clear or land as soon as practical.
• Incapacitated pilot — recommended practice: the nearest crew member initiates RTH, or a second qualified RP assumes control.

Post-crash procedure

1. Keep everyone clear of the wreck for 15 minutes — a damaged LiPo can ignite with delay. Approach from upwind.
2. Confirm DISARMED / kill power from the GCS or RC if any link remains.
3. Photograph the aircraft in place before touching anything — scene photos are part of the record and required for warranty assessment.
4. Disconnect and quarantine the battery in a fire-safe container, outdoors, away from buildings and vehicles. Treat it as damaged — do not recharge or reuse it.
5. Preserve the data: recover the onboard SD card intact, and save the GCS telemetry logs from the session. Do not power the autopilot back up “to check it”.
6. Record the occurrence in your technical log and report it to RFD with the logs and photos (see Support & Warranty).
7. 🚫 No return to flight after a crash without RFD’s clearance.

Lost-aircraft procedure

1. Do not shut down the GCS or RC — note the last known position, heading, altitude and ground speed from the GCS, and leave both links up: telemetry frequently returns as geometry changes.
2. If the aircraft was healthy when contact was lost, check the home point — it may have flown its RC-loss RTL and be waiting on the pad.
3. Search from the last telemetry point along track, then downwind — allow for wind drift during descent.
4. Report per your operator’s procedures (and CASA/ATSB obligations if the aircraft may pose a hazard or is unrecoverable), then notify RFD with the saved GCS logs.
5. When found, treat the site per the post-crash procedure above.

Occurrence reporting

Accidents and serious incidents carry operator reporting obligations (in Australia: ATSB immediately-reportable matters, and CASA per your ReOC procedures) — reporting to authorities is the operator’s responsibility. Separately, report every accident, defect, or in-flight anomaly to RFD with logs; fleet-wide findings are fed back to all owners as Service Bulletins.

9. Post-flight

Repeat the pre-flight inspection, paying particular attention to the propeller/vanes, motor mounts, the tail/lower fuselage (which take the landing impact), the battery (swelling/heat), and servos/linkages. Record any defect in your RPAS technical log.