WattFlyer RC Electric Flight Forums - Discuss radio control eflight - View Single Post - Do propellers really "unload" in flight?
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Old 09-21-2008, 11:09 PM
Look out for that tree!!!
Larry3215's Avatar
Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 7,061

Originally Posted by BEC View Post
The files are in the process of being sent right now (of course this post slows it down a bit....) Thunderbird says 49% so far.

Oooops - it timed out. I may have to do it in two notes (four files).

Added: looks like it went on the second try. 9335 Kb.
Originally Posted by everydayflyer View Post
Flew GP Electro Stick ,Scorpion 3020-12,APC 11X7E, OUTRAGE XP25 4S 3700.

Very short blip at beginning where I went barely past 50% Throttle for takeoff. Came back to 50% flew around level for a bit then did some loops,climbs and dives without touching the throttle. Next I bumped throttle up tp approx. 65% and did the same thing.

Added second attachment of complete flight.

Originally Posted by gzsfrk View Post
Quick! Someone call Mythbusters and suggest this myth to them!!

Of course, then there would be the inevitable Mythbusters-thread-war like we had with the "plane on a treadmill" myth. I don't know if stevecooper's heart can handle another discussion like that one.
I dont think we need the Myth Busters to generate a controvercy in most on-line forums

Thanks to everyone who has posted files/graphs so far.

Its clear from the data that the props DO indeed unload in flight.

The inflight max RPMs are higher than the static and the peak power levels do go down.

However, its also clear that under certain conditions, inflight loads can increase.

There are places in Bernards and Charles and Trams graphs where the power level is INCREASING while the battery voltage is dropping. Its obvious that the load is increasing at some points and decreasing at others.

Whats much more dificult to tell from any of the data so far, is how much of the drop in power is due to the prop unloading and how much is due to the battery voltage dropping.

I can tell that climbs and dives are occuring and that they do indeed effect the load on the motor - but Im not always sure that full or constant throttle was being maintained - or if the flight was level or not etc.

Tram hasnt sent me his graph yet, but it looks like I may get to do a flight in a few minutes. I can log all the relevant data and I will know how I was flying at any gievm point so I can - maybe - better determine how its working on my setup.

I'll be flying a very slow floater with a relatively small power system thats designed for 3D type slow flying. In other words - the system is pushing the limits at full power and is designed to be flown at 1/4 - 1/2 stick most of the flight with only short power bursts.

Thats how many systems are set up so it should be of some interest.
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