219g AUW Roma-F4

By Rickard on Jun 10, 2021

3  66  0

Reusing components from an old quad to make two new quads. This one focuses on making a quad for medium long range. Longer antennas, less weight and more efficient thrust using the same motors but with lower voltage and longer blades. This one has about the same bench test thrust output as the old quad, but since it is more efficient and the old quad was held back by battery sag, this one performs better for e.g. racing and freestyling (except when crashing). The battery sag for this one is extremely low, it can hold above 75% throttle for more than a whole minute.

Flight time

Some hover tests. Changing to 4 inch 3S from 3 inch 4S seems to have made the biggest improvement in flight time. With this quad I often land because I want to land and not because the battery is low.

  • old quad, 3x3x2 prop, new 4S 650mAh battery, 246g AUW: 7:30 min hover
  • old quad, 3x3x2 prop, 1 year old 4S 650mAh battery, 246g AUW: 6:00 min hover
  • new quad, 3x3x2 prop, 1 year old 4S 650mAh battery, 208g AUW: 7:20 min hover
  • new quad, 4x2.5x2 prop, new 3S 750mAh battery, 205g AUW: 12:00 min hover
  • new quad, 4x2.5x2 prop, new 3S 850mAh battery, 219g AUW: 12:30 min hover

Bad gyro data

I don't know if it is the FC, the build or something else that is wrong but the gyro signal is not good. Only bad gyro data on the pitch axis. Lots of noise in the long and low range 40 to 150 Hz. I have tested different filtering, PID tunes, rearranging wires to not be close to gyro and bending the long antenna to be held down by the battery strap. None has resulted in good gyro data or flight characteristics. It flies ok but not good.

I also tried flashing BLHeli_M (JazzMaverick) and using RPM filtering. The RPM filtering works well as usual, but low frequency noise on pitch does not seems to be directly related to motor frequency and is still there. What's worse is that now the quad sometimes starts with some functionality not working properly. Like does not receive radio signal. Or the Vista not sending any UART/OSD/telemetry data like battery voltage. Or terrible flight performance. The most frustrating part is that it only happens sometimes and sometimes not. I tried lowering the PID loop to 2k with Dshot150 to test if the FC was overloaded, but it did not help. I downgraded to BLHeli_S and have not had this problem yet.

Photos

Part List

Frame

Diatone Roma F4 LR 4" Frame (5 builds)
Racedayquads.com
$29.99

Flight Controller

BETAFPV AIO Brushless Flight Controller 20A F4 2-4S V3 Toothpick - Droneit
Droneit.se
$92.00

Motors

4 x FLYWOO NIN TINY NT1404 1404 3750KV 4850KV 2-4S Brushless Motor for RC Drone FPV Racing (7 builds)
Usa.banggood.com
$63.60

Propellers

HQ Prop Durable T4x2.5 Bi-Blade 4" Prop 4 Pack (23 builds)
Racedayquads.com
$2.99

FPV Camera

Caddx Nebula Pro 1/3 Cmos 2.1mm Lens FOV 150 Degree 720P/120fps Low Latency NTSC/PAL 4:3/16:9 Switchable HD Digital FPV Camera F (7 builds)
Banggood.com
$55.99

FPV Transmitter

Caddx Vista Unit for DJI Digital HD FPV (No Camera) (12 builds)
Getfpv.com
$115.99

Antenna

Caddx Vista antenna 15cm standard - Droneit
Droneit.se
$159.00

Batteries

Tattu R-Line 750mAh 11.1V 3S1P 95C XT30 Lipo Battery - Droneit
Droneit.se
$65.00

Batteries

Tattu 11.1V 3S 850mAh 75C LiPo Battery Pack with XT30 Plug for 150mm to 180mm Size Micro FPV Racing Quadcopters (2 builds)
Amazon.com
$19.99

Radio

DJI Digital FPV Remote Controller - Mode 2 (45 builds)
Racedayquads.com
$299.00

Goggles

(PRE-ORDER) DJI Digital FPV Goggles V2 - Ultra Low Latency 810p 144FPS Digital HD (109 builds)
Racedayquads.com
$569.00

Misc Parts

Ummagawd UMMAGRIP LITE Universal Super Sticky Battery PadDefault Title (26 builds)
Racedayquads.com
$4.59

Misc Parts

Super Loud 5V Active Alarm Buzzer Beeper Tracker 9x11.8 mm - Droneit
Droneit.se
$145.00

Battery Charger

Imax RC Ladegerät Battery Charger Imax B6AC + schwarz (3 builds)
Asmc.de
$83.06

Backpack

QuadGuard TX Case
Lowepro.com
See Site

Accessories

Jumper T16 Stick Ends Rocker (M3)
Unmannedtechshop.co.uk
$5.45

Accessories

Lumenier AXII HD DJI FPV LHCP Combo Set - Droneit
Droneit.se
$265.00
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