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Old 04-09-2014, 05:29 AM   #7
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Originally Posted by billp View Post
hello, im a newbie to rc planes.
i have a falconIII model plane that i finished converting to electric drive.
it was a kit i purchased over 20 years ago, and i finally got a chance to finish it this year.
the thing about the conversion, is that it bumped up the published flying weight from 4.5 lbs to 5 lbs, 12 oz.
the motor is an eflite power32, and the battery is a 4S, 3200mAh lipo.
the speed control is an eflite60 ESC.
now, i haven't flown the falconIII yet. i will be asking an experienced flyer at the flying club to take it up for a test flight.
however, before i do that, i would like to get any opinions from experienced flyers of the falconIII and falcon 56 airplanes, on the following question:

- is the current flying weight of my electric - converted falconIII
too heavy ???

thanx in advance, for your time.

I've run your numbers through Motocalc predicts that your motor will work well with a 12X6 APC-E prop on a 4S LiPo. Predicted power is 48 Amp, 670 Watts, with the motor turning that prop at about 9600 RPM. Motocalc predicts a climb out rate of 1600 feet per minute. This power system is running about 120 watts per pound of airplane. That is decent performance for this model.

It would be safe to run that motor with a 13X6 prop. But, don't do it unless you have access to one of those wattmeters, to make certain not to fry anything.

Five pounds, 12 ounces seems rather heavy for a Falcon 56. Have you weighed it with an accurate scale?

As for that Power 32, these electric power systems can have surprising power outputs, compared to a glow engine. The Power 32 motor has roughly the same horsepower as a glow four stroke 60 or 70 engine. I flew a Falcon 56 model back in the mid 1960's as glow power, using an Enya 35 Glow engine. It flew fairly well back then. Don't know about wing strength though, might be something to really take a close look at.

This guy is running a Power 60 motor and a 6S LiPo in his model, with a total weight of 7 pounds.

That's strange on that Power 60 Motor. Motocalc predicts this motor will only be running about 500 watts, with 80% efficiency. Planting a similar sized Hacker A50-12S motor with a 15X10 prop and a 5S LiPo will haul this model straight up at some 3000 feet per minute. And, probably tear the wings off. (I've got three Hacker A50-12S motors in my various models. Those models have about 65 inch wingspan, and are running about 8 pounds and 1300 Watts.)

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