BeQuiet! Light Wings (140 mm): Different size, different geometry

BeQuiet! Light Wings (BL075) in detail

We analyzed the “Light Wings” fan fairly recently, but that was in the 120 mm format. BeQuiet! approached the 140mm model a little differently. Although the frame is only proportionally enlarged, the shape of the rotor is already significantly different. It relies on long, curved blades, which look great in this cross-section, but there are some design caveats. Still, in some applications, this fan excels.

BeQuiet! Light Wings are one of those models with ARGB LEDs that direct the lighting away from the rotor, onto the frame. This has the advantage that a stronger material with more attractive properties can be used to produce the rotor itself to achieve the main thing – the highest possible airflow at the lowest possible noise level. This is also the direction that BeQuiet! took.

From the design details of the 140mm Light Wings fans, it can be seen that BeQuiet! was also working on the Silent Wings (Pro) 4 fans at the same time. We have tested the SWP4 fans in 120mm format some time ago, but the Light Wings model is the older one. The similarity with Silent Wings (Pro) 4 is that for the first time BeQuiet! has resorted to using extra long, slimmer blades with more pronounced leading edge curvature. And even the gaps between the blades are very small. This is also one of the characteristic features of the 120mm SW(P)4.

The surface of the blades is grooved across their width, as is typical for BeQuiet! fans. This treatment partially suppresses unwanted turbulence during air intake and at the same time (due to centrifugal force) does not cause longitudinal sliding of the air streams as it happens on smooth surfaces. Eventually, the grooved surface contributes to a higher air flow while at the same time reduces noise.

Geometrically, the 140mm Light Wings fan differs significantly from the 120mm one, the latter has wider, less curved blades with larger gaps (but this is also due to the smaller number of blades – seven instead of nine in the 140 mm variant). The rotor shape that is used on the larger format would be more what we would expect on the smaller one, but BeQuiet! did it this way. The advantage of this concept is that more of the outer cross section is active, hence higher static pressure and less air leakage.

The other side of the matter, however, is how the blades themselves are designed. First of all, they are really long and combined with the medium stiffness, which is determined by the thickness (around 2.5 mm), the material used (PBT), but also the curvature of the narrower side (“belly”), where during operation the “waving” intensify towards the tips of the blades, which stimulates unpleasant resonant frequencies in the sound. This is what disadvantages this fan the most. However, anti-vibration pads in the corners of the frame are conveniently used to suppress the transmission of vibrations to a case or a cooler.

And while we’re on the subject of the frame, it’s worth pointing out that in the “push” direction it presses down on the radiator very tightly. The gaps around the corners are only in the “pull” orientation. Then the static pressure drops and the airflow is similar to the Silent Wings Pro 4 fans with alternative corners.

Compared to the last tested 140 mm FD Aspect 14 fan, the Light Wings fan is significantly more robust, which is also reflected in the more than 50% higher weight (242 g). However, all Light Wings fans (i.e. including this model) are among those that can collide with a nylon filter. Although visually the circular light-conducting panel appears to be significantly forward of the rotor, the height difference between it and the highest point of the hub is very small, and thus mutual contact between the rotor and the mesh occurs with unreinforced fine filters.

In addition to the tested “high-speed” variant with a max. of 2200 rpm codenamed BL075, there is also a slower variant (BL074) topping out at about 1500 rpm. Light Wings fans use PWM control and are connected via a 50 cm long cable. The lighting is at 5 V (3-pin ARGB) and there are two connectors, female and male (for more convenient connection of another fan in series).

* When reading performance values, a certain amount of tolerance must always be taken into account. For maximum speeds, ±10 % is usually quoted, minimum speeds can vary considerably more from piece to piece, sometimes manufacturers will overlap by as much as ±50 %. This must then also be adequately taken into account for air flow, static pressure and noise levels. If only one value is given in a table entry, this means that it always refers to the situation at maximum speed, which is achieved at 12 V or 100 % PWM intensity. The manufacturer does not disclose the lower limit of the performance specifications in its materials in that case. The price in the last column is always approximate.

• Contents
• BeQuiet! Light Wings (BL075) in detail
• Basis of the methodology, the wind tunnel
• Mounting and vibration measurement
• Initial warm-up and speed recording
• Base 6 equal noise levels…
• ... and sound color (frequency characteristic)
• Static pressure measurement…
• … and airflow
• Everything changes with obstacles
• How we measure power draw and motor power
• Measuring the intensity (and power draw) of lighting
• Results: Speed
• Results: Airlow w/o obstacles
• Results: Airflow through a nylon filter
• Results: Airflow through a plastic filter
• Results: Airflow through a hexagonal grille
• Results: Airflow through a thinner radiator
• Results: Airflow through a thicker radiator
• Results: Static pressure w/o obstacles
• Results: Static pressure through a nylon filter
• Results: Static pressure through a plastic filter
• Results: Static pressure through a hexagonal grille
• Results: Static pressure through a thinner radiator
• Results: Static pressure through a thicker radiator
• Results: Static pressure, efficiency by orientation
• Reality vs. specifications
• Results: Frequency response of sound w/o obstacles
• Results: Frequency response of sound with a dust filter
• Results: Frequency response of sound with a hexagonal grille
• Results: Frequency response of sound with a radiator
• Results: Vibration, in total (3D vector length)
• Results: Vibration, X-axis
• Results: Vibration, Y-axis
• Results: Vibration, Z-axis
• Results: Power draw (and motor power)
• Results: Cooling performance per watt, airflow
• Results: Cooling performance per watt, static pressure
• Airflow per euro
• Static pressure per euro
• Results: Lighting – LED luminance and power draw
• Results: LED to motor power draw ratio
• Evaluation