Can anyone help me with solutions on controlling blade tip speed?

I used a calculator that Mr. Schmid recommended (http://www.ecalc.ch/helicalc_e.htm?ecalc) and finally found a combination that may work for the weight I want to lift.

I get a message saying that the Blade Tip Speed is over MACH .85

Is governing the max speed something I can program into the ESC calibration?

 

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William

The tipspeed is calculated at "full power". The quad should operate at 50%-60% to maintain maneuverability. Try to adjust KV-Voltage(number of cells)-Propsize accordingly. Try to keep the prop pitch as low as possible and the prop size as big as possible because you need thrust (and efficency) only and no speed. Thats why I suggested a "low" RPM, low pitch helihead. You can also go a bit higher in power than the Motor is rated as long as you do not add to much payload. But thats all to be tested. The calculator is well tested and the values I measured in the past years differ a view % only. But thats all based on fixed wing projects.

For my small custom quad (70cm) I used the same method and I am fine with the result. http://www.youtube.com/watch?v=7cPELHYOiWI

 

Send me your calcs for comment PM if you want.

Christof

Christof

Great help.  Does a 3 blade prop give better results in lifting a quad?

Hi William

 

To be frank, I dont know. I was reading about that a while ago. When I rember right, you can reduce tip speed and diam by using more than 2 blades with a little less efficiency . But that applies more to big aircrafts due to noise reduction. What does the calculator say?

I would use 2 blades because of balance. Its very tricky to balance more bladed props. Its already difficult to balance 2 bladed props. And most of us can not dynamicaly balance.

Furthermore, there are very view puller and pusher in 3 blades on the market.

 

I would be interested in a precise information as well. Maybe someone else could say more about that topic.  

 

Christof

   

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