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I wanted to calculate the amount of thrust generated from the engines. I am using the blade 180 cfx model.

http://www.bladehelis.com/Products/Default.aspx?ProdID=BLH3450#quickSpecs

After some research I have found a way to calculate the thrust using:

T = ( pi D^2 rho P^2)/2 where P is the Power multiplier and can be calculated using: P= prop constant * (rpm/100)^power factor

I am unable to find the values for the Prop constant and the power factor. Is there a way I can get this information? Or an alternative way to calculate the thrust generated?

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The easiest way to calculate this will probably be by using the ecalc helicopter calculator, they have done all these calculations for you and take into account far more factors in my experience they are very accurate. I know that most props have a Prop Constant in the 1.1 to 1.3 range, but for your specific situation according to ecalc gives a thrust to weight ratio of 2.49:1 for a 190g helicopter giving 283.1g of payload capacity or 473g of lift.

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  • $\begingroup$ Thank you for the link. This is very helpful and I happened to have this exact same question. BTW, recommended settings are 12º of pitch and max headspeed of 5,000 RPM. This generates a static thrust of 325g (for the 2 blade version). $\endgroup$ – B Seven Aug 1 '18 at 23:26
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After using ecalc (which is an awesome tool!) I discovered that I could approximate the results using Disk Area * RPM.

It's not useful for getting thrust in grams, but good for comparing changes in Blade size and RPM.

Disk Area * RPM vs Thrust

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