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Old Oct 31, 2005, 10:40 PM
roccobro is offline
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San Bernardino, CA
Joined Aug 2003
6,512 Posts
Idea
Alfa Fan motor and power testing :D

The Alfa EDF's have become the "new wattage" in that they are bringing in alot of new EDF fliers with their simple, fun to fly depron planes. And like the Wattage F-86 and Mig the Alfa can be hopped up with a variety of motor and battery combinations. The TP PL's are poplular and the Himax 2025-5300 on 3s is the most common setup with a respectable output.

Although the plane is "just foam" and the fan unit isn't "perfect", I have undertaken the chance to try alot of different motors in the Alfa fan unit. There are other brand fan combos that might fit an Alfa power junkies bill, but I wish to keep this motor power upgrade testing "stock" in that the new Alfa owner won't be ditching the expensive fan unit out of a kit that only comes only in a fan/plane combo.

A motors ability to spin at an rpm under a given load is a function of its torque ability. Generally, the larger the motor can diam, the greater its ability to create torque than from another motor of the same length or weight. A lower Kv motor puts it's torque band in a lower rpm, and with light weight lipos bursting from the market, adding another cell to up a low Kv motor to EDF use is easy and economical. High V/ Low A setup are also fun in that a proper motor battery combo coupled together make for a powerful setup, that sometimes has a weight loss and lower cost benefit from the smaller capacity batteries and lower (lighter) rated ESC's needed.

The alfa fan is designed for a speed 300 motor, but has room in the motor tube to be machined open for a larger Mega 16/x/x series motor to fit. The 16/7/x series is a great compact powerhouse, and actually weighs less than the Himax 2025 motors. You can buy a premachined Alfa fan housing and a reamed rotor adapter from www.Euromodels.com.au. All my New Mega motors over the years have come from Randy at www.dynamoelectrics.com and these two tested here were no different. Both shops offer excellent service, and in Randy's case, shipping is really fast. Although HobbyLobby is the sole US importer of Alfa stuff, you CANNOT order spare fan parts unless it's special order with a 6-8 week wait for delivery! The good news for a new EDF nut with his Alfa bird can take his fan unit and open up the fan motor tube themselves, and drill out the "adapter" to fit the Mega's 3.2mm shaft.

Another Mod that can be done to increase the serviceablility of the fan unit, and aid in fan balance is to drill and tap the rotor adapter for two 2.5mm setscrews. This eliminates "glueing" the loose fit rotor button on the motor shaft, that usually leads to an out of balance rotor. Tower Hobbies has tap sets for a great price, and they can be used to drill and tap the adapter in less than 5 minutes. 2.5mm setscrews can be bought from RTLfastners.com or from any GWS shop that sells replacement EDF-55/64 impeller adapter setsrcews.


Enough background, here is a screen shot of data for where I am at in my "testing". I hope to complete it to my satisfaction this week. Tomorrow should be dedicated to the 16/7/3, and then back to the Himax 4200 with a proper inlet lip. WOW, what a difference an inlet lip makes on this fan. In the process of my testing, I have found a "need" to try out some hacker motors since Philpops and Zimmerman have upped the Alfa anty in this thread.

Just to be clear, this is all static testing. While EDF *generally* don't unload in the air under regular flight, ones fan/motor combo might make different thrust readings based on many things. Inlet and outlet in my testing shows a BIG difference, and a podded installation as I am testing will have different "thrust" readings than from a unit inside a fuse. One key thing to watch is the RPM. And EDF's ability to make power (thrust or efflux) is dependant on it's rotor rpm. There are other factors that can affect "thrust" but anmost every install will be different. Again, RPM is an important reading in measuring an EDF units performance.

If you see any flaws in my data or post, please help us all out and provide the correct information. I am not perfect, and won't stake my life on my equipment. They are just the average brands of average tools other modellors have and use.

Justin

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Last edited by roccobro; Nov 03, 2005 at 01:13 PM. Reason: Updated the chart
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