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Old Nov 04, 2008, 07:59 PM
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leadfeather's Avatar
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Video
Prop in slot noise test

Here is a video of a small test for the FireFly which was done to see if I could improve the noise generated by the "prop in slot".

There are 3 clips: 1) As built, 2) tapered forward edge 3) and curvy glade propeller.

See if you can hear a difference.

Thread on the FireFly: http://www.rcgroups.com/forums/showthread.php?t=943610

Update Nov 06, 08. Second video added comparing straight slot to dogbone slot.
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Last edited by leadfeather; Nov 06, 2008 at 08:11 AM.
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Old Nov 04, 2008, 08:13 PM
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United States, PA, Bellefonte
Joined Dec 2007
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Quote:
Originally Posted by leadfeather
Here is a video of a small test for the FireFly which was done to see if I could improve the noise generated by the "prop in slot".

There are 3 clips: 1) As built, 2) tapered forward edge 3) and curvy glade propeller.

See if you can hear a difference.

Thread on the FireFly: http://www.rcgroups.com/forums/showthread.php?t=943610
With head phones, Test 3 had a deeper tone and a little less volume, I would say. Seems like test 2 started out quiet to start, but 2 didn't jump to full throttle as fast as 1.
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Old Nov 06, 2008, 09:14 AM
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A second test was done to compare slot shapes. The video was added to the first post.
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Old Nov 07, 2008, 06:35 PM
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Canton, Michigan, United States
Joined Nov 2000
334 Posts
Prop Distance

IMHO, I think that the dogbone, in your testing, was probably the quietest.

FWIW, I had wondered a while back, during the "Zagi Craze", about prop noise. I wondered why a gunther prop made so much noise on my Zagi in pusher configuration, but was very quiet in tractor mode on my Tumblewatt. My conclusion was that the proximity of anything close to the spinning prop is what caused noise. The Zagi was noisey because the prop was so close to the trailing edge of the model!

Try this! Take a motor with a spinning prop (on or off a model) and while holding it in your hand, move an object slowly as close to the prop as you can. By the time you get within a half inch, you will start to hear noise.

Unfortunately, for your mid-mounted prop your only choice is to make a bigger gap in front of and behind the prop.
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Old Nov 07, 2008, 06:51 PM
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North London ENGLAND
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Hi Leadfeather.Interested in the pic of the foreplane delta with tiger stripes. Made a slimer powered plane like that a few years back in Canada. Flew well once CG sorted,(started out a bit nose heavy).
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Old Nov 07, 2008, 07:41 PM
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Quote:
Originally Posted by macboffin
Hi Leadfeather.Interested in the pic of the foreplane delta with tiger stripes. Made a slimer powered plane like that a few years back in Canada. Flew well once CG sorted,(started out a bit nose heavy).

Hi Macboffin,

It is a VTOL tail sitter jet called the LevJet

Hovers, VTOL's and flies great.
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