# T200 performance with relative speed

Hey,
I understand that the CVC file included all T200 performance measured while the thruster was static. Right now I try to calculate its performance while moving.
I hope that same-one succeded to bridge the gap.
I will be glode for your help

Hi @Yuval, welcome to the forum

Indeed, as per the testing notes in the data file,

Whatâ€™s the intended use-case/end result here?

Performance while moving is a full â€śspaceâ€ť rather than a simple relation (input â†’ output) of values, so is difficult to measure and quantify in a meaningful way. The water can be moving at different speeds, in different directions, and with varying levels of turbidity, and can also include particulate matter, which may all have differing effects individually and together. While it would be possible to measure performance in a particular set of conditions, even measuring the conditions themselves accurately is challenging (speed isnâ€™t too bad, water direction and turbidity are difficult, particulate matter is an additional issue). Covering the full space of conditions that people are likely to come across includes many combinations with complicated setup and measurements, so isnâ€™t something weâ€™ve done at this point in time.

If youâ€™re after a transient response or similar, these are the best resources Iâ€™ve come across previously:

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Hey,
you are right, this is all most impossible to measure all of the conditions. Even though, itâ€™s very common when speaking on propellor separately (without a motor) to show the performance graph, as shown here:

I have tried to extract from your data the curve, but because of all of the tests done at rest, the advance ratio is always zero. Iâ€™m pretty sure that if you were making the test with velocity (say 1 m/s) it could be possible to extract the non-dimensional parameters curve. From there the calculation of the performance for all speeds would be easy.

I will take a look at the post.

Thanks a lot!

Advance ratio calculation relies on freestream fluid velocity, which generally requires an â€śopen-waterâ€ť type test. Our thruster performance data comes from testing in a tank, and that tank is small enough that itâ€™s not feasible to measure fluid velocity in a way that isnâ€™t impacted by local effects of the thruster (since quite soon after the water starts being pushed forwards, it comes around the sides and comes back in at the back).

Itâ€™s understandably much easier to get a highly consistent testing setup and rigorous measurements in a fixed tank than it is while attempting to tow an entire setup through open water at a fixed speed. It could also be possible to make a much larger tank and pump water through it at a fixed speed, but presumably the costs of installation, setup, and maintenance of that are prohibitive given the small amount of data that it would be used to generate.

Regardless, Iâ€™ll register your interest in moving-water testing data, and hopefully weâ€™ll be able to measure some of it at some point

I was looking for the same information and curve, much like Yuval was.

It appears that no oneâ€™s done the testing yet. Iâ€™ve got a tow tank and weâ€™ve been meaning to test out a new load cell. I think Iâ€™ll corner an undergrad and together weâ€™ll characterize it!

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