QAV-ULX is a 5″ mini quad racing frame by Lumenier. It’s designed to use as little material as possible (thus the skinny arms), and the result weights only 45g!

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The QAV-ULX is available at GetFPV. Review is written by Artur Banach.

Frame Overview

QAV-ULX stands for QAV “UltraLight X Frame”, it indicates that the frame is meant to be super light weight. According to Lumenier, it was designed to have as little flex as possible for optimal flight performance and tune-ability. It has a shape of a tower where electronic components are a part of the structure.

Frame kit included:

• 6 x 4mm carbon fibre arm 5″ (2 extra included)
• 6 x 4mm carbon fibre arm braces – 3 x Bottom Plate (1 extra included)
• 3 x side racks
• 2 x FPV Top Plates (1 extra included)
• 2 x LOS Top Plates (1 extra included)
• 2 x G10 SMA Antenna holder (1 extra included)
• XT-60 pigtail
• Lumenier small lipo strap
• 4in1 Lumenier ESC
• 1 x Neophrene foam tape

Frame weights:

• 46g – all small plates included and hardware, without braces
• 53g with 4in1 ESC board and Flight Controller
• 76g with arm braces

Motor to motor distance is 185mm and it can take 5″ props max.

Closer Look and Review

The idea about this frame is by using narrower arms to reduce the total frame weight, yet allowing easier frame part replacement in the field.

The QAV-ULX is designed as a FPV racing frame, therefore there is no option for mounting GoPro or Xiaomi YI on the top of the tower. The frame can also be built for Line of Sight (LOS) type of flying by using supplied plates that protects the top of the Flight Controller (shorter standoffs and lower tower).

Motors are attached to the arms with 2 bolts. They can be screwed with standard M3x5mm screws if frame is assembled without the arm braces. With the braces installed it’s best to use M3x12mm screw.

The QAV-ULX is designed for 5″ props but it is really tiny compared to my hand.

Good things about the frame

• Footprint of a 4″ frame but allows 5″ props – that means smaller moment of inertia and better agility
• Really light weight
• Tower design reduces the amount of wires required and simplifies the build, very compact design
• 4in1 ESC also works as a PDB
• Spare carbon fbre parts included
• It’s easy to replace the arms (even in the field) thanks to the modular design
• Good carbon fibre quality
• Very stiff design with nearly no flex even without the braces

Disadvantages

• Tower design may not appeal to everyone
• No option to carry HD camera
• Flight controller is a part of the tower and it has a higher chance of getting damaged when the tower takes hit
• Not much protection for motors, this is imporved with braces attached
• Arms are too narrow to hold normal standalone ESCs, it’s doable but not ideal, it’s best to use 4in1 ESC for this design
• Frame is more fragile than other “more meaty” frames
• I feel like it’s more suitable for experienced builders due to the limited space

Build log

For the QAV-ULX I used the following parts:

• Lumenier „Skitzo” RB2205 2400kv with ceramic bearings
• Lumenier 20A x4 4 in 1 BLHEli-s ESC
• Foxeer TM200 Video Transmitter
• Lumenier CM-650 FPV Camera
• FrSky X4R-SB SBUS Radio Reciever

Preparations

I have started the build by replacing 20AWG power wires on 4 in 1 ESC to 16AWG that came with the kit and also shortened them. Also fed the small lipo strap trough the cutouts on the bottom plate. Installed motors onto the frame base and added ESC board.

LEDs, Motors, ESC

Added the color changeable LEDs to the underside of the rear arms and soldered their power wires to the underside of the power pads on ESC. Adjusted the motor wires lengths and soldered them to the pads on ESC.

Wires, Flight Controller, Radio Receiver

Measured: motor signal, Flight Controller power and radio receiver wires and trimmed them to be as short as possible but to have a bit of room for movement still. Soldered them to a Flight Controller. Radio Receiver was stripped down from the packaging, depinned and wires soldered directly. I placed it underneath Flight Controller and above the ESC with antenna wires facing back of the quad. Video Transmitter power wires were soldered directly to lipo pad on the 4 in 1 ESC. In fact, this was the one and the onlym set of pads I used to power everything on this quad since no Power Distribution Board (PDB) was used here.

Radio Receiver antenna and final touch

Screwed the spacers onto the threaded rods that came with the kit. Antenna wires were looped around the rear standoffs and heashrinked. Same method I used on Alien 6″ build.

Prepared Video Transmitter and FPV Camera. I used two of the G10 SMA antenna holder plates for more durability but because it screws on the top of the plate, I used longer screwed there (M3x8). I didn’t use any of the side rack plates because they were not needed here in my build.

Voil’a – another mini quad was just created :)

Weight

• Fully built QAV-ULX without lipo and with props weights 260g
• With Dinogy Graphene 1300 4S lipo, and ready to fly it weights 410g

Lumenier clearly achieved the low weight goal here. This is by far the lightest 5″ quad I’ve ever built and reviewed. Even if we added the HD camera (GoPro) to this, it would still be less than 500g.

Flying experience (IN PROGRESS)

I have yet flown this quad due to my busy day job, I will post further assessment after flying it. I will also add some videos to this review.

Conclusion

QAV-ULX is quite an unusual mini quad frame because it’s modular and every part of the frame can be easily replaced after it’s broken. It’s not the kind of crash-proof frames that you can take to a car park and smash around with, but rather a specialised FPV racing frame that takes advantages of light weight and decent aerodynamics.