Thread: New Product Change Sun 10 blade 70mm
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Old Oct 11, 2012, 12:29 AM
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Extreme CNC Alloy EDF
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Quote:
Originally Posted by anlucas View Post
Just quoting results in a format that others have decided upon a long time before I ever decided to get involved in electric RC models....I 'd be happy to adapt to whatever format the mass wants...
Its a hard one to answer as there have been many variations over the past couple of years in here. When I started recording EDF data back in 2005 for my own interest I was taking snap shots of amps, watts, volts, (rpm once I got a hyperion meter) and I was taking these figures after the system had been running for a little while, maybe 20 seconds or more.

I continue to record data after a settle period so that the battery voltage stabilises, to me this was the most useful measurement, peaks are not much use, sustained flight readings are.

Recently peak thrust numbers have been used to exaggerate how good a particular fan/setup is, marketing spin that really doesnt have much value in the real world. I see little point in claiming for instance 2.95kg thrust from your fan peak, when it actually sits around 2.6kg stabilised 30 seconds into the run.

I believe figures taken after 20+ seconds of continuous WOT running are worthwhile figures, they show us how much the battery voltage has dropped under the load which gives a good indication of whether the load is too much for the battery being used, and they show us a fairly stable rpm and thrust reading if the equipment is on hand to record it.

Even 5 years ago companies like Hyperion were talking about battery voltages and what was considered a reasonable drop under load, from memory 3.5v per cell was considered the minimum you wanted to see for long term pack life, I am sure they based this on the cell structure at the time and how hot it got if pushed harder. The Koreans were also the leaders in lipo technology at the time, chinese cells could not compete.

These days we are dealing with a vast range of battery quality, from premium grade 1 cells to the really cheap lipos, so there is much more to quantify when testing stuff whether it be hobbyist or commercial based testing. Some of the cheap lipos will put out just as much power as a premium pack when brand new, this does not last however, cycle life is a lot harder to graph as it requires someone to actually do it over a period of time. I have done it a couple of times comparing other packs to my own and its tedious, obviously the results are not something I would talk about on a forum as it would be seen as bias. It has proven to be extremely interesting however!


As I have posted many times in the past, it would be nice to see a standard method of testing and recording that is along the lines of:
Use an inlet lip if the fan has no radius on the intake.
Run the fan up to WOT.
Let it run for 20 seconds.
Record volts, amps, watts, rpm and thrust from the meters while its running.
And to make it more complete, post up these figures along with the battery size and rating.
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