Matching a Reference Fan’s Air Speed: Why the Whole Design Matters

When a buyer sends a reference fan and asks for similar air speed, the development task begins with a comparison—not an immediate component change.

Increasing motor speed or replacing the impeller may help, but neither guarantees that a different fan assembly will match the reference. The motor, control board, impeller and surrounding air path need to work together within the project’s cost and design constraints.

In a recent Kinscoter development project, the customer’s goal was to bring a prototype’s air speed close to a supplied sample while keeping costs manageable. A series of configuration tests helped identify which combinations moved the prototype closer to that target.

The results also showed why a change that works in one configuration may offer little benefit in another.

Define What “Matching the Sample” Means

“Similar wind strength” is a useful starting description, but it needs a measurable definition before development decisions can be compared.

For this project, the comparison focused on air speed at a fixed measurement position. The reference sample recorded 5.2 m/s under the test setup.

The measurement conditions were:

Here, “average” refers to the instrument’s sampling average at the selected position. It is not an average across the entire outlet area.

That distinction matters. Matching this reading would show similar air speed at the test position; it would not, by itself, establish identical airflow distribution, noise, runtime or user experience.

The highest setting was used for each configuration, but this should not be interpreted as identical motor RPM across configurations.

Compare Combinations Before Choosing a Modification

The prototype control board was modified to increase the motor drive voltage, with the aim of raising motor speed. No other control-board changes were reported for that modification.

The team then compared different combinations of control board, motor, impeller and front grille.

The same five-blade impeller was used across the five-blade tests, and the same seven-blade impeller was used across the seven-blade tests. For Configurations 3 and 5, the front grille was the only structural difference: the rear grille, remaining air path and impeller mounting position were unchanged.

Recorded Air Speed by Configuration

These are the recorded values supplied for this development comparison. They describe the tested configurations under the stated setup, rather than universal performance ratings.

What the Results Tell Us

Changing the Impeller Did Not Produce the Same Result in Every Setup

Configurations 1 and 2 both recorded 4.8 m/s. With the modified prototype board and original motor, replacing the seven-blade impeller with the five-blade impeller did not change the reported value at the displayed precision.

The result was different with the reference motor and board. Configuration 3, using the five-blade impeller, recorded 5.0 m/s. Configuration 4, using the seven-blade impeller, recorded 4.7 m/s.

The useful conclusion is specific: the five-blade impeller produced the higher reading in the reference motor-and-board configuration tested here.

It does not establish that fewer blades always produce stronger airflow. It shows why the impeller should be evaluated with the motor and drive arrangement intended for the product.

The Motor and Control Board Must Be Considered Together

Configurations 2 and 3 used the same prototype structure and five-blade impeller. Replacing the original motor and modified prototype board with the reference motor and board changed the recorded value from 4.8 to 5.0 m/s.

Because the motor and board changed together, this comparison does not isolate the motor’s contribution.

For a buyer, that is an important development distinction. A promising motor test may point toward a different drive arrangement as well, rather than a simple motor substitution.

The supplied results also do not include a before-and-after comparison of the original and modified prototype board. They therefore cannot quantify the improvement attributable to the voltage adjustment alone.

The Two Front Grilles Produced the Same Reported Reading

Configurations 3 and 5 differed only in the front grille. Both recorded 5.0 m/s.

Under this setup, the custom grille and the standard radial grille produced the same reported air-speed value at the measurement position.

This is useful evidence when reviewing whether to retain a preferred grille design. However, it does not establish identical airflow across the full outlet, identical noise, or equivalent behavior at every operating setting.

A Remaining Gap Needs Further Investigation

The best recorded prototype configurations reached 5.0 m/s, compared with the reference sample’s 5.2 m/s.

That leaves a recorded difference of 0.2 m/s. The table alone does not establish its cause or whether it exceeds the combined measurement uncertainty and run-to-run variation.

The next step is to examine repeat readings and the remaining differences between assemblies. It would be premature to attribute the gap entirely to the rear grille or another untested feature.

Why the Air Path Belongs in the Development Review

A motor and impeller operate within a surrounding structure. The inlet, outlet and internal geometry are therefore part of the performance question.

Fan manufacturers’ technical guidance describes installed performance in terms of both fan characteristics and system resistance. This supports evaluating the complete assembly, rather than selecting a motor only by its standalone specifications.

In a compact fan project, a practical review can include the rear inlet openings, front grille, clearances around the impeller and internal obstructions. These are areas to investigate—not automatic explanations for a particular test result.

Where possible, change one feature at a time and repeat the same measurement procedure. If several components must change together, describe the result as a comparison between configurations rather than proof of one component’s effect.

Keep the Cost Target in the Decision

The customer’s objective in this project was to approach the reference air speed within a manageable cost range.

That makes the decision broader than choosing the configuration with the highest reading. Before selecting a production direction, the team should also evaluate:

• Motor and control-board cost.

• Any tooling changes required by structural revisions.

• Power consumption and operating temperature.

• Noise and battery runtime.

• Component availability and production consistency.

These are follow-up evaluation items; the air-speed table does not establish their results.

A useful development discussion presents the buyer with the measured improvement, the remaining uncertainty and the cost of pursuing the next change. This makes it easier to decide whether a closer match justifies additional development.

What Buyers Should Provide with a Reference Fan

A physical sample is most useful when it comes with a clear brief.

Tell the supplier which characteristics matter most: measured air speed, airflow coverage, noise, runtime, appearance or a particular combination. Identify which parts of the design can change and which must remain fixed.

For an air-speed target, agree on the measurement distance, probe position, operating setting, power conditions and acceptable tolerance. If the reference has been tested internally, share the procedure as well as the headline number.

You can use Kinscoter’s custom product development overview to discuss whether the project should begin with an existing product, a platform modification or a new design.

A Better Starting Point for Sample Matching

This comparison shows why reference-sample matching benefits from structured testing. An impeller change produced different results with different motor-and-board combinations, while two front grilles produced the same reported reading under one controlled setup.

For buyers, the practical question is: which combination gets sufficiently close to the target while meeting the project’s other requirements?

Share your reference sample, target cost and performance priorities through Kinscoter’s product review and quotation service. A defined target and a consistent test method give both teams a clearer basis for deciding what to adjust next.