mucksmear

Hello,

Anyone know if a gear-reduced speed 400 is any quieter than a direct drive speed 400? I ask because friends direct drive Picojet is quite lound in an anoying highpitched hairdryer sort of way. Are these s400 motors just generally loud?

Thanks in advance-
-E

RC_Eflyer-RCU

Direct drive motors are generally quiter. But I'm assuming your friend is running a Gunther prop on his PJ which are a louder prop. The other thing is that its all foam. There is kindo a resonance in the foam that causes it to be very loud. Other foamies are the same way. Your Zagi's and the like. I had a Twinstar which had 2 motors and it was fairly loud in the air. Not as loud as a slimer of course, but loud for an electric.

--Paul

mpj220

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mucksmear

Thanks for all the info guys.
Come to think of it, I recall hearing about the increased noise of pusher props in close proximity to a trailing edge. I have a pusher design here that I might alter by extending the aft fuse just a bit farther beyond the TE. I think the main issue for me to fly it in my "quiet" neighborhood is to get a more pleasing sound (lower pitch). Even if it measuers the same db.

-E

camilleg

I've tried half a dozen props and three motors with picojet -- all are loud. The same prop on a projeti is about 20 dB quieter. The folding prop on my graupner terry is far far quieter.

(All these are direct drive foamies.)

From this I suspect that either the relatively exposed motor position on the picojet, or the greater amount of foam near the prop (i.e. turbulent airflow into the prop), account for the noise.

I haven't heard geared sp400's yet, but don't take picojet as typical of direct-drive quietness!

But it's only logical that a big geared prop moves more air less violently and thus is quieter. Whether the gear noise itself counteracts this... i'll bet you a quarter that there's more variability within the families of direct-drive and geared ships,
than between the two.