Turbine or Small Propeller for Phoenix EDF Models?
 

Hello,

I'm modeling a twin-electric-ducted-fan plane in Phoenix Builder. I'm building this virtual model to try to predict the performance of the actual scale model that I plan to build.

I've been using small-diameter, ten-blade propellers with 50,000 RPM and blade pitch based on a 45-degree angle at the tip. These specs are based on the 64mm fan/motor combos that I'm thinking of using in the actual model.

Someone mentioned that perhaps it would be more accurate to use turbines set at the published thrust of the EDFs. Or perhaps somewhat lower, since published specs often are optimistic.


Any thoughts on which method would give a more accurate performance: fan-sized propeller blades or small-thrust turbines?

Thanks, Bill

Update:

I'd love to get confirmation or correction for the assumptions mentioned below.

The twin-engine model I'm testing in Phoenix has a 50-inch wingspan and weight of 60 ounces. Two 64mm EDFs of the type I'm considering have a combined published thrust of 2.8 kg, or 99 ounces.

For my testing of a turbine version of the Phoenix model, I used the following turbine specs:

Max RPM: 50,000 (based on published figures for the EDF)

Max. Thrust: 10. I'm assuming "N" in the Builder list means "newtons." If not, please let me know. The published thrust of the EDFs I'm thinking of using is 13.7 newtons. To be conservative, I'm using 70 percent of the published thrust.

Engine: Medium electric. Is my assumption correct that this value is mainly for the sound rather than performance? If so, it seems appropriate because it gives a hum but not the roar of the turbine options.

One question: The depiction of the turbine in Builder is large, as seen in the image below. Does it matter? When I use Edit to look at published turbine models, the turbines look much smaller. I tried changing the Scale values to make the image smaller, but nothing changed. Is the size of the image relevant to the performance of the model in Phoenix?

Thanks,
Bill

http://www.rcuniverse.com/forum/atta...mentid=2091088