KISS of calm --- 6S whisperer / 128 kHz / Druckbär Ultralight 4 / FETtec 2104 /

By MamaJOE on Sep 10, 2021

13  282  2

The story behind the build

The starting point of this build was a repetitive situation that I assume most of you know:
Angry people coming towards you and yelling at you to get out of here with that bothersome "thing"...
I don't like this experience - and that's the reason, why I wanted to build a quad that's as silent as possible, but without limiting flight performance.

Choice of components

It was clear to me, that a 5- or 6-blade prop should be quieter, so I searched for a suitable prop.
The only one I found was the HQProp 4x4x6, what defined the build to be 4".
Furthermore I want as high PWM as possible, why I chose the FETtec ESC with 128 kHz.
After that I had to look for suitable motors. And on my search I found this Quadmovr video.
So the choice for the motors was clear an I changed my mind, to make it 6S instead of 4S :)
Of course the weight got a big influence on the noise level. So I watched out for a lightweight but durable frame.
I found the Ultralight 4 frame which seemed to be a good choice.


The build was pretty straightforward without bigger problems.
I really like the look of the motors, so I tried to match the color scheme of the raw aluminum for the entire build.
But the stack and Vista didn't fit in the frame, so I put the ESC under the base plate, as I did with my toothpick build.
I had to make my own mount for the video antenna, where I chose aluminum of course.
This is the first time I have mounted the Immortal T on the front. The reason is that I can (mis)use it here as a bumper for the ESC deck.
But since it's easy and cheap to replace, that seems like a good idea.
The video system is detachable, for easy access to the FC.

Flight quality

This thing is really silent - completely comparable to the video above.
And it's damn fast... Not as fast as in the video (because of the higher weight), but it's really amazing!
The tuning was pretty difficult - on stock PIDs it's more or less unflyable.
I found a good tuning, but here I have to spend more work to get the last 10 %.


Weight with props: 199 g
AUW with 6S 650 mAh: 312 g
Flight time (650 mAh): approx. 3:30 to 5:30


Part List


Ultralight 4


Conversion Kit (25,5x25,5mm / 30,5 x 30,5mm)

Flight Controller

FETtec KISS FC (2 builds)


FETtec 4in1 ESC 35A V1.1


4 x FETtec Motor FM2104M - 1800KV (3 builds)


HQProp Duct-4X4X6 for Cinewhoop Grey (2CW+2CCW)-Poly Carbonate

FPV Camera

Caddx Nebula Pro Vista Kit 720p/120fps low latency Digital HD FPV system (3 builds)


Polar Antenna




TBS Crossfire Nano Rx - FPV LONG RANGE DRONE RECEIVER (1147 builds)


Tattu R-Line 650mAh 22.2V 95C 6S1P Lipo Battery Pack with XT30 Plug (3 builds)

Power Distribution

FETtec Spike-Absorber (3 builds)


Gaoneng GNB 7,4 V 3000 mAh 5C 2S Lipo Batterie XT30 Stecker für Jumper T16/T18 RADIOMASTER TX16S Sender


RadioMaster TX16S Multi-Protocol RF Module OpenTX 2.4GHz RC Transmitter w/ Hall Gimbals (69 builds)


URUAV V2 3 in 1 Dust-proof Shading Sheet Protective Lens Cover for DJI Digital FPV Googles


DJI Digital HD FPV Goggles (101 builds)


iFlight Crystal HD Patch 5.8GHz RP-SMA Antenna for DJI - LHCP - Choose Your Design (2 builds)


2 x Double Quad RX Black Edition LHCP RP-SMA male speziell fr DJI HD FPV System (2 builds)


Replacement DJI FPV Goggles Sponge Foam Padding


Ersatz Akku Li-Ion 4,4Ah (4 * 18650 Akku) + Tasche für - - und andere LED-Lampen mit 7,


CopterFarm Super Sticky Cow Tongue Pad Batterie LiPo


2 x Taste Kopf M2 Titan schrauben M2x3 M2x4 M2x5 M2x6 M2x7 M2x8 M2x10 M2x12 M2x14 M2x16 M2x18 M2x20 Hex Fahrer Ti GR2

Misc Parts

Matek Lost Model Beeper & FPV FC 5V Loud Buzzer (28 builds)

Misc Parts

Plasti Dip Liquid Electrical Tape schwarz 118ml 4oz black (3 builds)

Radio Module

TBS Crossfire Micro TX V2 (36 builds)

Battery Charger

2 x Power Genius SAFE Parallel board XT30 and XT60 2S to 6S with Fuse Protection (3 builds)

Battery Charger

2 x BAT-Safe LiPo Tresor sicheres Laden und Aufbewahren der Akkus

Battery Charger

2 x Amacoam 2 Stück Lipo Batterie Sicherer Beutel Feuerfeste Explosionsschutz Lipo Battery Guard Tasche Sack Gebühren Schutz Tasch

Battery Charger

ISDT D2 200W 24A AC Dual Channel Output Smart Battery Balance Charger (17 builds)

Soldering Iron

Tilswall Lötstation 65W Lötkolben Set 200°-480°, mit 5 Ersatzspitzen und Lötzinn, einstellbarer Temperatur, eingebaute Tran (2 builds)


Skyreat Hard Carrying Case for DJI FPV V2 Goggles


Tarion Pro PB-01 Professional Camera Backpack


Kesser® Campingstuhl faltbar klappbar tragbar Angel Stuhl Camping Stuhl Faltstuhl bis 120 kg Strandstuhl Angelstuhl Klapphocker
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Sign in to comment

MamaJOE   6 days ago  

Almost... I have used the original top-plate as an additional bottom-plate (rotated by 180). The plate from the conversion kit is mounted on top, as intended 😉

juliett.papa   7 days ago  

Wow. Very nice and clean build! Did you use the conversion kit as an additional bottom plate?

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