6' Relay Ping Wing FPV + 4' Razor Wing FPV + RadioMaster TX16S Transmitter with Crossfire Module
6' Relay Pink Wing FPV + 4' Razor Wing FPV : Radio and Flight Controller Setup
6' Relay Ping Wing FPV + 4' Razor Wing FPV + RadioMaster TX16S Transmitter with
Crossfire Module
This 6' wingspan pink foam FPV wing is used as an airborne relay for
controlling the Razor 4' FPV wing. This flying combination uses the most
complicated radio and electronics setup that I have ever implemented for the RC
hobby. The EdgeTx and
iNav software settings are defined below. The photos above shows the Relay and Razor wings together;
the image on the left shows them after their first
dual flight in Maryland in 2024, and the image on the right shows them
after their first dual flight in Texas in 2026. Power for the 6' wing comes from a 480 outrunner with a 50A ESC, running on
a 3S lipo.
FLYING - FPV
Both planes are controlled from a single RadioMaster TX16S transmitter
running EdgeTx software, with a Crossfire RF module. The TX16S
transmitter does not directly control the Razor wing, as the control
link goes from the TX16S to the Relay wing via Crossfire, and then from
the Relay wing Crossfire receiver to a Lemon DSMP transmitter module in
the Relay wing via PPM, and then back down to the Razor via DSMX. The
video link is similar but in the opposite direction; the Razor’s video
transmitter is on 5.8 GHz frequency B, which is received by a video receiver in
the Relay wing. The Relay wing then re-transmits that video signal using
its own video transmitter on 5.8 GHz frequency A. Video goggles on the ground
monitor frequency A. I keep frequencies A and B as far apart as
possible, such as E3 and E6.
Using this wing as a relay station for both control uplink and video
downlink allows for line of sight (LOS) from the ground to the FPV Relay
wing flying high to the Razor FPV wing flying low. The Relay wing has a
GPS receiver and a F4 flight controller running iNav 7 software,
allowing for autonomous navigation. The Relay wing is launched first, flown
to altitude, and then placed in position and altitude hold; a circling loiter. The Razor wing is
then launched and flown normally, with its control and video links passing through
the Relay wing. Once the Razor wing has landed, the Relay wing is taken
out of autonomous loiter and landed normally. The Relay wing also has
its own on-board camera. A remote controlled video switch in the Relay
wing is used to select which signal is sent to its video transmitter;
the Relay wing’s own camera or the video signal received from the Razor
wing. A SmartAudio connection from the Relay wing flight controller to
its video transmitter allows for instant video transmitter power
control from the ground via iNav's logic functions.
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Omnibus F4 V3 flight controller, with baro pressure sensor, 3-6S input (PDF
manual by Von Flori)
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Remote Power Switch
Relay + Razor Checklist Sequence
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Crossfire Uplink Channels from RadioMaster TX16S :
Eight channels of control allows for :
iNav Channel Input Order : TREA1234 |
 Relay Wing Architecture |
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Relay Wing Controls Throttle (1) Relay Wing & Razor Throttle Rudder (2) Razor Roll (= inverted Relay Wing Roll command) Elevator (3) Relay Wing & Razor Pitch Aileron (4) Relay Wing Roll SH (5) Razor Stabilizaion ON/OFF SE (5) Relay Wing Equipment ON/OFF (middle – no effect) : Power to DSMP module & Video Receiver SF (6) Relay Wing Motor ARM/DISARM 6 Buttons (6) Relay Wing Flight Modes SB (7) Relay Wing video switch ON-BOARD CAMERA/VIDEO RECEIVER SA (7) Relay Wing Video Tx RF Power – HIGH/LOW (middle – no effect) Dial S2: (8) Razor Stability Master Gain, low to high |
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Crossfire Uplink Channel 5 = Aux1 : Switch SH + Switch SE - Razor stabilization on/off + Relay Wing relay equipment ( video receiver + Lemon DSMP Module ) power on/off - Switch SH ( 90% mix ) : - high : PWM = 1960 μs (1500 + 460) : Lemon Stabilized Receiver in second aircraft looks for PWM > 1500 μs for STABILIZER ON - low : PWM = 1040 μs (1500 - 460) : Lemon Stabilized Receiver in second aircraft looks for PWM < 1500 μs for STABILIZER OFF - Switch SE ( 10% mix ) : - high : iNav logic condition looks for PWM = 1908 μs (1960 – 52) or PWM = 988 μs (1040 – 52) [ SE-high offset from SH-high or SH-low ] --> this causes flight controller servo output #3 to be high, which turns power switch ON - middle : no effect to current command - low : iNav logic condition looks for PWM = 2012 μs (1960 + 52) or PWM = 1090 μs (1040 + 52) [ SE-low offset from SH-high or SH-low ] --> this causes flight controller servo output #3 to be low, which turns power switch OFF |
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Crossfire Uplink Channel 6 = Aux2 : Switch SF + 6 Buttons - Relay Wing motor arm/disarm + Relay Wing flight mode
- each iNav flight mode has two valid ranges :
Button 1 - 6 offsets from SF-high or SF-low - when button 4 or 5 is active, the Aileron command is centered so that roll commands meant for the Razor do not affect iNav Position Hold [ nav_user_control_mode = atti ]
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throttle commands meant for the Razor do not affect iNav Altitude Hold [
nav_fw_allow_manual_thr_increase = off ]
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| Crossfire Uplink Channel 7 = Aux3 : Switch SB + Switch SA - Relay Wing video transmitter power + Relay Wing video switch - Switch SB ( 50% mix with modification for middle position ) : - high & middle: PWM = 1756 μs (1500 + 256) : iNav logic condition looks for PWM > 1500 μs --> this causes flight controller servo output #4 to be high which in turn causes the video switch to pass on-board camera signal to OSD - low : PWM = 1244 μs (1500 - 256) : iNav logic condition looks for PWM < 1500 μs --> this causes flight controller servo output #4 to be low which in turn causes the video switch to pass video receiver signal (from second aircraft) to OSD - Switch SA (25% mix) : - high : iNav logic condition looks for PWM = 1628 μs (1756 - 128) or PWM = 1116 μs (1244 - 128) [ SA-high offset from SB-high or SB-low ] --> this causes flight controller to use SmartAudio to set video transmitter to high power - middle : no effect to current command - low : iNav logic condition looks for PWM = 1884 μs (1756 + 128) or PWM = 1372 μs (1244 + 128) [ SA-low offset from SB-high or SB-low ] --> this causes flight controller to use SmartAudio to set video transmitter to low power Crossfire Uplink Channel 8 = Aux4 : Dial S2 - Razor Lemon Stabilized Receiver master gain - Dial S2 : continuously variable from 1000 μs to 2000 μs, low to high gain |
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F4 Flight Controller iNav 7.1.1
PWM Channel Outputs (mmix and smix): [ Flight Controller Outputs ] <insert image capture of iNav Programming Tab |
 PPM Signal Conditioner, 3.3V LVTTL to 5V TTL |
