Total noob here. I’ve been scouring the forum for answers and my old eyes are burning, so I decided to admit ignorance and ask, hoping to save some time.
The model (see image, attached) is approx 27.7 inches in diameter. It’s estimated weight will be in the neighborhood of 1Kg.
I intend to build a fixture to suspend it upside down by four load sensors spaced evenly about the model’s perimeter.
Once it is suspended in the fixture, I will weigh it. Then I will spin up the rotors to design point rpm and weigh it again. The difference in the two measurements will give me the thrust of the model.
I will need to be able to measure and log the forces from each of the four sensors separately. The reason that I’m going to use four separate sensors is to measure the loads at periphery during attitude control inputs; inputs which will control the model’s attitude, i.e. pitch and roll. Yaw (rotation about the vertical axis) will not be considered in the initial tests. If my thinking is correct, summing the forces should result in the total force.
Any help is appreciated.
Thanks in advance,
saucerdesigner
Hi saucerdesigner,
Four load sensors might work here but those are best for measuring cumulative weight like a scale. In order to measure the weight/pressure of each “corner”, you would need to use a load cell with its own amplifier on each corner since there is not an easy way to differentiate between the input from several load cells attached to something like our [HX711 Breakout or the [SparkFun OpenScale. If you have not already, I would recommend reading through our Hookup Guides for both of those boards along with our [Getting Started with Load Cells Guide.
I hope this helps you get started with this project. If you have any follow-up questions about these or other SparkFun products in your project, let us know and we would be happy to help as much as we can.](https://learn.sparkfun.com/tutorials/getting-started-with-load-cells)](SparkFun OpenScale - SEN-13261 - SparkFun Electronics)](https://www.sparkfun.com/products/13879)
Thank you TS-Mark; it helps. I’ve begun going through the Getting Started with Load Cells>Suggested readings tutorials. The estimated thrust is going to be on the order of 3.5kg.
4 ea. 1kg straight bar load cells would be ideal if available. I didn’t see one. Would 4 ea. 5kg be overkill - not sensitive enough? Thanks again. ~ sd
Hi again,
Unfortunately, we do not have a 1kg straight bar load cell but I agree, that would be ideal for this project. 5kg load cells would work but since you are only using roughly 1/5 of the total output of the cell, your readings are not going to be as accurate as they could be with a 1kg. Ideally, you want to have your load being measured to be as close as possible to the Full Scale of the load cell.
