How to build a simple wind tunnel force balance?

In summary: I'm trying to use load cells or strain gauges that can be hooked up to digital readouts. Need some mechanical contraption that can isolate the lift and drag forces as much as possible...??
  • #1
foxkilo
2
0
I have constructed a wind tunnel with approximately 15 x 15 in. cross-sectional area test section.

Where can i get some ideas/plans to build a simple force balance that can measure lift and drag forces simultaneously?

Currently I'm using a single-axis button load-cell setup to measure drag. How to design a mounting solution for another load cell to measure the lift force? Or there are much better ways of doing this, e.g. using strain gauges? :confused:

Need not be too accurate; this tunnel is intended for educational purposes only. Any help is appreciated, thanks.
 
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  • #2
foxkilo said:
Need not be too accurate; this tunnel is intended for educational purposes only. Any help is appreciated, thanks.

:rolleyes:
hang the model from a spring scale
 
  • #3
OK, I need enough accuracy to run experiments such as plotting CL and CD vs. angle of attack. :biggrin:

I'm trying to use load cells or strain gauges that can be hooked up to digital readouts.

Need some mechanical contraption that can isolate the lift and drag forces as much as possible...??

Like for example, I'm currently using an L-bar pivoting at the intersection of the L, model mounted on the tip of the longer end of the "L", and load cell placed under the short end. Drag forces pull the model back, the L-bar pivots and applies a load to the load cell... But this method only measures DRAG... so I have a one-trick pony here...
 
  • #4
Obviously, you ll be putting this L section somewhere, just put a weighing scale below it, difference in weight gives u the lift.

Again if size of the weighing scale is an issue, you can use a platform & use load cells below it(at least three, & of course a bit of calibration), to see the vertical force.

hey, may I know what does the model look like?
 
  • #5
foxkilo said:
OK, I need enough accuracy to run experiments such as plotting CL and CD vs. angle of attack. :biggrin:

I'm trying to use load cells or strain gauges that can be hooked up to digital readouts.

Need some mechanical contraption that can isolate the lift and drag forces as much as possible...??

Like for example, I'm currently using an L-bar pivoting at the intersection of the L, model mounted on the tip of the longer end of the "L", and load cell placed under the short end. Drag forces pull the model back, the L-bar pivots and applies a load to the load cell... But this method only measures DRAG... so I have a one-trick pony here...

What type of load cell are you using because I am trying to preform a project to reduce drag on airplane wings using winglets?
 

1. How do I determine the size and shape of my wind tunnel force balance?

The size and shape of a wind tunnel force balance will depend on the specific needs and parameters of your experiment. Generally, it should be designed to fit comfortably within your wind tunnel and be able to accommodate the forces and pressures that will be applied. You may also need to consider the number and placement of sensors on the balance.

2. What materials should I use to build a wind tunnel force balance?

The materials used to build a wind tunnel force balance should be strong, lightweight, and able to withstand the forces and pressures of the wind tunnel. Common materials include aluminum, steel, and carbon fiber. It is important to choose materials that are also non-reactive and will not interfere with any measurements.

3. How do I calibrate a wind tunnel force balance?

Calibrating a wind tunnel force balance involves determining the relationship between the output of the balance (usually in the form of voltage or current) and the forces being applied. This can be done by applying known forces to the balance and recording the corresponding output. The calibration data can then be used to convert the output into accurate force measurements.

4. What types of sensors should be used on a wind tunnel force balance?

The type of sensors used on a wind tunnel force balance will depend on the specific forces and pressures being measured. Some common sensors include strain gauges, pressure transducers, and accelerometers. It is important to choose sensors that are sensitive and accurate enough for your experiment.

5. How do I ensure accurate and precise measurements from a wind tunnel force balance?

To ensure accurate and precise measurements from a wind tunnel force balance, it is important to properly calibrate the balance, use appropriate sensors, and carefully design and build the balance to minimize sources of error. Regular maintenance and cleaning of the balance can also help maintain its accuracy and precision over time.

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