INAV T-tail Layout Fixed-wing Tuning Guide

7/15/25About 11 min

This tutorial is based on INAV 7.0.0 firmware. Operations may vary slightly with different firmware versions.
Some content is quoted from the SpeedyBee APP interface and is consistent with INAV Ground Station settings.
You may use either the SpeedyBee APP or INAV Ground Station for configuration and tuning.

I. Introduction to Flight Principles

The inverted T-tail (also known as the Conventional Tail) is one of the most common tail designs for fixed-wing aircraft.

It consists of a horizontal stabilizer and a vertical stabilizer. The horizontal stabilizer is mounted at the rear of the fuselage, below the main wing, while the vertical stabilizer is positioned centrally on the fuselage, forming an inverted “T” shape.

This layout places the horizontal tailplane below the main wing, giving it more direct exposure to airflow compared to a high-mounted T-tail. As a result, it offers the following characteristics:

Lower dependence on angle of attack: The tailplane receives a more stable airflow, reducing the risk of stall during high-angle flight.
More direct pitch control: The horizontal stabilizer is closer to the airflow behind the main wing, resulting in more responsive elevator control and smoother pitch input.
Better wind resistance: Compared to the elevated T-tail configuration, the lower-mounted tail is less affected by crosswinds, providing greater stability during landing.

II. Equipment Preparation

Required Equipment:

1.Flight Controller: Any of the following are compatible with this tutorial: SpeedyBee F405 WING APP / SpeedyBee F405 WING MINI / SpeedyBee F405 WING APP V2

2.Transmitter: Example models: RadioMaster Boxer / RadioMaster TX16S

3.Receiver: Example: SpeedyBee ELRS Nano 2.4G RX receiver

4.GPS Module: Example: BeiZheng BZ-251 GPS module

5.Motor: Zhuhang OEM 2212 KV980 motor, suitable for FeiWeng aircraft (for reference only)

6.ESC: 35–45A electronic speed controller, suitable for FeiWeng aircraft (for reference only)

7.Servo: 12g metal servo, suitable for FeiWeng aircraft (for reference only)

8.Battery: 6S1P 10000mAh battery, suitable for FeiWeng aircraft (for reference only)

9.Propeller: 8-inch two-blade propeller, suitable for FeiWeng aircraft (for reference only)

Optional Equipment:

1.Analog Video Transmission: For example, SpeedyBee TX1600 VTX and RunCam Phoenix2 SE V2 camera.

2.HD Video Transmission: For example, DJI O4 AIR UNIT.

3.Airspeed Sensor: It is recommended to use a digital airspeed sensor.

For Ground Station Installation, refer to this article: https://docs.speedybee.cn/plane/software/insoftware/inav-version-install.html How to update flight controller firmware using INAV Ground Station: https://docs.speedybee.cn/plane/beforetuning/inav-fw-update.html

III. Initial Setup

3.1 Model Configuration

Use a USB data cable to connect the flight controller to the ground station
Open the INAV Ground Station and click Connect

If a pop-up appears, select Airplane with a Tail

Go to the Mixer tab，Select Airplane，Select Airplane again, then click Load and Apply

3.2 Accelerometer Calibration

⚠️ Note: Before calibrating the accelerometer, be sure to remove the flight controller from the fuselage and place it on a flat surface. This ensures accurate calibration and stable flight performance.

Go to the Configuration page
Select Auto to automatically detect sensors and confirm that the accelerometer is recognized

If the accelerometer icon appears red, try reflashing the firmware. If the issue persists, contact customer support.

Click Calibration
Click Calibrate Accelerometer
Calibrate according to the instructions shown in the diagram

For each side, you need to click Calibrate Accelerometer once after placing the flight controller in position

The diagrams below correspond exactly to each step of the accelerometer calibration described above.

After calibration is complete, click Save and Reboot.

3.3 Port Configuration

Go to the Ports page
Configure according to the reference table
Click Save and Reboot

3.4 GPS Configuration

Enabling GPS is required in order to access the NAV RTH (Return to Home) flight mode in the Modes page.

Go to the GPS page
Enable the option GPS for navigation and telemetry
Click Save and Reboot

3.5 Transmitter and Flight Mode Setup

3.5.1 Transmitter Setup

1.Please bind the transmitter to the receiver before proceeding with the following steps.
2.For details on how to bind an ELRS receiver to the transmitter, refer to this article: https://docs.speedybee.cn/plane/ardupilot/settings/rc/elrs-bind.html

Go to the Receiver page
Configure according to the diagram
Click Save and Reboot

For detailed instructions on how to set channel endpoints in EdgeTX, refer to this article: https://docs.speedybee.cn/plane/inav/settings/rc/edgetx-endpoint-setup.html

Navigate to the MDL / MIXES page on your transmitter.Check if channels CH1–CH4 are configured as shown If not, adjust the transmitter mixes accordingly

3.5.2 Arming Channel Setup

1. Transmitter Setup

Select a two-position switch
Navigate to the MDL / MIXES page and assign it to CH5

2. Ground Station Setup

⚠️ Note: Arming is only allowed in flight modes that do not require GPS, such as ANGLE (Stabilized). Arming is not possible in GPS-dependent modes like NAV ALTHOLD.

Go to the Modes page
Set the ARM (Arm/Disarm) channel to CH5, with a value range of min: 1700 – max: 2100
Click Save

3.5.3 Return-to-Home (RTH) Channel Setup

1. Transmitter Setup

Select a two-position switch
Navigate to the MDL / MIXES page and assign it to CH6 (You may use a different channel based on your setup; this is for reference only)

2. RTH Switch Setup

By default, RTH mode will only activate if the aircraft is more than 5 meters away from its home point. Within 5 meters, the OSD will not display RTH mode!

Go to the Modes page
Set the NAV RTH (Return to Home) channel to CH6, with a range of min: 1700 – max: 2100
Click Save

3.5.4 Flight Mode Configuration

1. Transmitter Setup

Choose a three-position switch to assign three flight modes
Navigate to the MDL / MIXES page and assign it to CH8

2. Ground Station Setup

Go to the Modes page
Set ANGLE (Stabilized Mode) to CH8 as shown.To add multiple values, click Add range
Combine AUTOTUNE with ANGLE as shown
Click Save

For detailed flight mode explanations: https://docs.speedybee.cn/plane/inav/settings/fc/flight-modes.html

IV. Equipment Installation

4.1 FC Wiring

Power Wiring

⚠️ Notes:
1.The positive wire must be connected to the specified pad
2.ESC refers to the electronic speed controller
3.Ensure solid solder joints to avoid cold soldering

4.2 FC Mounting

The FC should be installed at the aircraft’s center of gravity. Refer to the image for mounting guidance.

If you need to change the installation orientation: https://docs.speedybee.cn/plane/inav/settings/fc/fc-orientation.html

4.3 Peripheral Installation & Configuration

Peripheral wiring

4.3.1 Receiver Installation

Refer to the diagram for mounting position.Route the antennas out of the fuselage and secure them with tape.

4.3.2 Mixer Setup (Servos and Motors) & Surface Check

Enable Servo and Motor Outputs:

1.Motors and servos only function after output is enabled
2.In fixed-wing mode, you must enable motor stop at low throttle to prevent accidental spin after arming
3.For multirotors, disable "motor stop at low throttle" to enable idle spinning

Output Wiring:
The FC has a built-in BEC. If your ESC also has a BEC, remove the middle red power wire and insulate it to prevent short circuits caused by contact during flight.

Parameter Setup:

Go to the Mixer page
Configure as shown
Click Save and Reboot

Channel Output Description:

Channel	Function
S1	Throttle
S2	Throttle
S3	Elevator
S4	Left Aileron
S5	Right Aileron
S6	Rudder

Control Surface Check:

a. Stabilized Mode (ANGLE)

First, calibrate the compass,Wait 30 seconds , Click Save and Reboot

Switch flight mode to ANGLE

When the aircraft rolls to the left, the left aileron moves down, and the right aileron moves up.
When the aircraft rolls to the right, the left aileron moves up, and the right aileron moves down.

When the aircraft pitches up, the elevator surface moves down.
When the aircraft pitches down, the elevator surface moves up.

b. Control Surface Check in Manual Mode

Switch the flight mode to ACRO

When the aileron stick is pushed left, the left aileron moves up, and the right aileron moves down.
When the aileron stick is pushed right, the left aileron moves down, and the right aileron moves up.

When the elevator stick is pushed up, the elevator surface moves down.
When the elevator stick is pushed down, the elevator surface moves up.

When the rudder stick is pushed to the left, the rudder surface moves left.
When the rudder stick is pushed to the right, the rudder surface moves right.

First, check whether the stabilization feedback is correct.If it’s not correct, simply reverse the output by setting the corresponding value to a negative number.

For example, if you tilt the aircraft to the left while in stabilized mode, the control surfaces should attempt to level the aircraft.In this case, the left aileron should move down and the right aileron should move up.If the left aileron moves in the opposite direction, you can fix it by reversing SERVO1.

Then, check whether the manual feedback is correct.If the manual control direction is incorrect, you’ll need to reverse it in your transmitter settings.

For example, on an EdgeTX transmitter, navigate to MDL → INPUT and set the Weight value to -100 to reverse the manual input direction.

4.3.3 GPS Installation and Setup

Mount the module as shown in the diagram. Use 3M adhesive on the bottom of the module to secure it firmly. Improper installation may significantly affect flight performance.

Make sure to install the module level and upright without any tilting, otherwise the installation angle cannot be configured correctly.

1.Keep away from metal parts like magnetic covers or metal rods
2.Avoid placing near receivers, servo wires, or motor.
3.Ensure secure mounting
4.Refer to your GPS module’s manual for details

For detailed instructions on how to install and configure the compass orientation, please refer to the following article: https://docs.speedybee.cn/plane/inav/settings/gps/inav-compass-setup.html

Parameter Setup:

4.3.4 Video Transmission Device Installation and OSD Configuration

Analog Video Transmitter Installation:

Analog Video Transmitter Parameter Setup:

HD Video Transmitter Installation:

HD Video Transmitter Parameter Setup:

OSD Configuration:

OSD configuration file:INAV_OSD文件.zip can be downloaded and imported directly
Go to the CLI page
Click Load from File
Select the OSD file
Wait for the import to complete
Click Save Setting

4.3.5 Airspeed Sensor Installation and Setup

Airspeed sensor mounting reference:

For detailed instructions on airspeed sensor installation, parameter configuration, and calibration, please refer to this article: https://docs.speedybee.cn/plane/inav/settings/airspeed/setup.html

V. Pre-Flight Tuning

5.1 ESC Calibration

⚠️ Ensure the battery is disconnected and propellers are removed!

① Go to the Output page

② Check the risk acknowledgment box

③ Move Master slider to 100%

④ Power the FC using battery

⑤ When ESC beeps:→ Move Master back to 0% → Wait for calibration tones

Calibration Sounds:

BLHeli32/BLHeli_S:
- Connect the battery and wait for 2 seconds → a melody will play, indicating maximum throttle detected → wait for the melody to finish → move the throttle stick to minimum and wait 1 second → another melody (da-da) will play, indicating minimum throttle detected → calibration complete.
PWM ESCs:
- Connect the battery and wait for 2 seconds → “beep-beep” sound indicates maximum throttle detected → move the throttle to minimum and wait for 1 second → a series of short beeps indicates the number of LiPo cells → a single “beep” confirms minimum throttle detected → calibration complete.

⑤ Lightly push throttle; motor should spin immediately

⑥ If behavior differs, unplug battery and repeat from step ②

For enabling DShot protocol: https://docs.speedybee.cn/plane/inav/settings/esc/esc-calib-dshot.html

5.2 Motor Direction & Prop Installation

Use CW or CCW props according to motor spin
Install props with labeled side facing forward

To reverse motor direction, swap any two of the three motor wires

5.3 Compass Calibration

Confirm compass orientation before calibration!

Go to the Configuration page
Select Auto to auto-detect.Ensure the compass is properly detected.

If the compass icon appears red, it means the compass is not recognized correctly. Please check the wiring or ensure the compass is working properly!

Go to Calibrate page
Tap Calibrate Compass
Rotate aircraft 360° along all axes within 30 seconds

5.4 Failsafe Setup

Go to the Failsafe page
Select RTH to ensure that the aircraft can automatically return and loiter overhead via the flight controller in case of signal loss.
Click Save and Reboot

Go to Advanced Tuning
Set parameters as shown
Ensure values in red boxes are set to NEVER

After completing the setup, make sure to click Save and Reboot to save the parameters.

Click Advanced Tuning
Adjust cruise throttle as needed
Click Save and Reboot

It is recommended to enter the Advanced Tuning menu during the first return-to-home flight and allow manual throttle adjustment to prevent the default return speed from being too low, reducing the risk of accidents.

VI. Flight Test

6.1 Arming Pre-Check

For common arming issues, refer to: https://docs.speedybee.cn/plane/inav/settings/fc/fcproblem/unlock-fail-common.html

6.2 Pre-Flight Checklist

6.2.1 Center of Gravity (CG) Check

1.Refer to the markings on the fuselage:

The fuselage of a fixed-wing aircraft usually has markings indicating the recommended center of gravity（CG） , typically located 25–30% back from the leading edge of the main wing.

2. Two-Finger Balancing Method:

Place the aircraft on two fingers under the recommended CG point on the main wing and gently balance the fuselage
If the nose is too heavy or the tail is too heavy, adjust the battery position or add/remove counterweight

Nose-Heavy (CG too far forward):

The aircraft will have difficulty climbing during flight and may crash during takeoff
Solution: Move the battery backward or reduce nose weight

Tail-Heavy (CG too far back):

The aircraft may pitch up easily and stall
Solution: Move the battery forward or add weight to the nose

6.2.2 Control Surface Check Before Takeoff

Switch flight mode to ANGLE:

When the aircraft rolls left, the left aileron moves down, and the right aileron moves up
When the aircraft rolls right, the left aileron moves up, and the right aileron moves down
When the aircraft pitches up, the elevator moves down
When the aircraft pitches down, the elevator moves up

Switch flight mode to ACRO:

When the aileron stick is pushed left, the left aileron moves up, and the right aileron moves down
When the aileron stick is pushed right, the left aileron moves down, and the right aileron moves up
When the elevator stick is pushed up, the elevator moves down
When the elevator stick is pushed down, the elevator moves up
When the rudder stick is pushed left, the rudder moves left
When the rudder stick is pushed right, the rudder moves right

6.2.3 GPS Satellite Count Check

When outdoors, check that the number of satellites is greater than 8—only then is it safe to take off!
If the satellite count stays below 8, move to a more open area. If the issue persists, consider replacing the GPS module.

6.2.4 Wind Direction Confirmation

Observe wind direction:
- Watch for visual cues like smoke, wind vanes, or flags
- Toss a light object (e.g., a blade of grass) into the air and observe the direction it drifts
Determine headwind takeoff direction:
- Taking off into the wind provides more lift and reduces the required takeoff speed
- Taking off with a tailwind increases the risk of stall or nose dip, which may result in a crash

6.3 Takeoff Guidelines

Choose hand launch or rolling takeoff based on the actual aircraft configuration to ensure a smooth takeoff.

6.3.1 Hand Launch Takeoff

1. Mode preparation:

◦ Select ACRO mode to ensure full control surface authority

◦ Set throttle to 60%–80% to ensure sufficient takeoff thrust

2. Launch posture:

◦ Hold the aircraft under the wing; for flying wings, grip the wing directly to avoid injury

◦ Throw the aircraft at an upward 30° angle to ensure enough lift

3. Throwing technique:

◦ Use moderate force—avoid throwing too hard or too weak (which may not allow climbing)

◦ Push the aircraft forward smoothly, not downward

Important Notes:
Avoid hand launching at low throttle,ensure there is enough thrust for takeoff.
Immediately take control of the roll stick after release to prevent the aircraft from rolling out of control.

6.3.2 Rolling Takeoff

Select ACRO mode
Increase throttle to 60%–70% and maintain steady acceleration
Keep the direction stable to avoid yaw deviation during rollout
Once the aircraft reaches sufficient speed, gently pull up on the elevator to lift off smoothly

Important Notes: 1.Ensure the takeoff area is long enough—avoid steep climbs in short distances, which may cause stalls
2.Perform the takeoff into the wind to increase lift and reduce the impact of crosswinds
3.Monitor flight attitude to prevent excessive pitch-up or sharp banking

6.4 In-Flight Testing

1. Control Surface Test:

After a successful takeoff, switch the flight mode to ANGLE and observe whether the aircraft automatically corrects its attitude

If the aircraft behaves abnormally, switch to ACRO mode to land, then inspect control surface behavior under ANGLE mode

2. Level Flight Test:

Maintain throttle at 45%–55%, and check if the aircraft can fly level without diving or climbing

If the aircraft dives or climbs, recalibrate the horizontal level using AUTOLEVEL to ensure the flight controller is aligned with the wing
For detailed instructions on how to use AUTOLEVEL, refer to: https://docs.speedybee.cn/plane/inav/settings/fc/autolevel-autotune.html

AUTOLEVEL must be used in combination with a primary flight mode such as ANGLE. Refer to the AUTOTUNE setup section in the flight mode configuration for details on how to enable this combination.

3. Auto-Tuning:

Switch the flight mode to AUTOTUNE to begin automatic tuning

For detailed instructions on how to use Auto-Tune, refer to: https://docs.speedybee.cn/plane/inav/settings/fc/autolevel-autotune.html

4. Flight Data Check:

Monitor OSD data to verify that GPS, heading, altitude, ground speed, voltage, and current readings are all normal

If any data appears abnormal, land immediately and inspect the equipment

5. Return-to-Home (RTH) Function Test:

Switch the flight mode to RTH and check whether the aircraft returns and loiters above the takeoff point

If the aircraft behaves erratically in RTH mode, immediately switch back to ACRO or ANGLE and review the RTH configuration parameters

6. Pre-Landing Check:

Confirm there is enough remaining battery to complete landing
Observe wind direction and choose to land against the wind for improved control and stability