QUIET Wood Props

[plane]

I know that MSC and Vess have had a mission statement of making a wood prop that pulls good AND is quiet. To some degree they have had some success at the expense of RPM's.

Now, I do remember the original PK props and Bambula props. Both VERY quiet and both had one thing in common...square tips. Square as looking like the wingtip on an Extra, Edge, or any other aerobatic plane.

The problem with this design is it isn't very marketable. They look UGLY and that's why Bambula dumped quiet for sexy. Even PK props have the Menz swept look now.

If you're bored to death try squaring the tip of one of your old wood props and notice how the ripping sound decreases. Try it with a prop that was more load than the motor liked and you might end up with a prop that you'll like more than any other.

I'm talking about props in the 32 range but it'll also work for the 28 range.

[Ando]

Hmm, sounds like someone doesn't like the ripping sound... You can rip a 24 range prop to, just not as loud as a 32.

[XJet]

Strangely enough (albeit on glow motors), I find the square-tipped K-series Master Airscrew props rip *real* bad when compared to the more eliptical APC props.

I work at a full-sized airfield and I notice that the full-sized planes with square-tiped props rip a whole lot worse than those with rounded tips.

[todhog]

If prop ripping is what I think it is, the tips going supersonic, then the longer a prop is the easier it will be to rip. Cutting the tips off square makes the prop shorter. Maybe that's why three blades are quieter, the blade length is shorter.

Todd

[XJet]

I don't think it's solely the tips going super/transonic. I can get an MAS 12x6 to "rip" at 12,000 RPMs, which equates to a tip-speed of about 428mph, well under supersonic.

I also find that a 12" round-tipped prop (like a Bolly) doesn't rip at 12,500 RPMs -- in which case it has a higher tip-speed.

I suspect the amount of energy that goes into making the tip vortex has a huge effect. An eliptical or rounded tip will have a "softer" vortex (lower energy) than a prop with a squared tip -- hence less noise.

[EddieWeeks]

I built a 28x10 prop with variable pitch and it is by far the quietest prop
around. This is done by not letting the RPMs increase pass say 5500 or 6000.
But if you don't increase the pitch when you should, it will rip with the best of them.. hahah

Eddie

[adrian]

Eddie i have seen the vid's - your whole set up rips, no it actually rocks!!!!lol

[EddieWeeks]

I wonder if a high power electric plane will rip a 28" prop.. ?

Eddie