What is this style of prop?

[joshuabardwell]

I purchased these props:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=38712

They have a different shape than the ones I normally buy--straighter edges vs. more curved. And they have a hexagonal shape where the adapter ring should go, instead of a round shape. What is their intended purpose?

Here's another one:

http://www.buddyrc.com/gemfan-direct-drive-9x5-inch-propeller.html

This is more like what I usually buy.

http://www.buddyrc.com/gemfan-thin-electric-9x6-inch-propellers-a-pair.html

 

[joshuabardwell]

I have another question that I'll stick here... what is a slow-fly prop? Is it just a normal prop with a reduced pitch? Or is there a difference between, say, a 9x5 slow-fly and a "regular" 9x5?

 

[HawkMan]

Don't quote me on this, but I "think"(and I might e wrong) that a low flyer prop is merely made to be more efficient at lower rpm and ant handle high rpm without flying apart. They also have that special slow flyer look.

The 1045 slow flyers work great on my reptile500 quad on 900kv motors though, but with significantly less thrust than the 1050 carbons(I guess that half a turn inquires bit of thrust difference at 10 inches).

 

[Foam Addict]

To your original question, the props you purchased just now are known as Hyper Drive props, or just HD for short. They were designed by gws to be very efficient on mid power brushed motors, but can also handle >250 watt brushless motors. They are also some of, if not the most efficient mid to low rpm park flyer props that have ever been made. A slow fly prop is the more curved blade shape. These were designed for >400 class brushed motors, and are very efficient below say 4000 RPM for a 9-10 inch diameter prop, above 6000 rpm, they often disintegrate and are at minimum far less efficient, drawing more amps and producing less thrust than a "standard" prop. I hope this helps!

 

[Bleumunkie]

I have another question that I'll stick here... what is a slow-fly prop? Is it just a normal prop with a reduced pitch? Or is there a difference between, say, a 9x5 slow-fly and a "regular" 9x5?

Picture looking at the side of a wing of say the FT Duster VS the FT Old Fogey and you should visually understand the difference a bit.

 

[Craftydan]

"Slow fly" is just that -- it's designed for slow flight.

A standard prop of the same size will be quite a bit beefier in cross section and will take quite a few more RPMs before flattening under the pressure. Unfortunatly, I've yet to hear a good rule of thumb about wattage or RPM maximums for slow fly props -- each OEM may have a good max RPM/in rating for each class of prop, but few will publish them

APC, however is one of that does and their specs are fairly instructive:

http://www.apcprop.com/v/html/rpm_limits.html

As you can see, the same sized APC slowfly will top out nearly 1/3 of what a thin electric can and nearly 1/4 what a racing prop can do. Has nothing to do with the speed of sound (well, almost nothing) and everything to do with squishing blades.

 

[TEAJR66]

Those are GWS style propeller's. The hex shape is for the 3m nut that goes on threaded shaft motors or gear boxes. That prop will also work on motors with prop savers. Those props are ideal for this type of motor
http://www.graysonhobby.com/catalog/disposablefoamiecombosport18aescthreadshaft-p-624.html
The nut fits in the hex shaped hole and done. no prop saver no prop adapter.

The last prop you have linked is more like an APC Style prop. They would require a prop saver or prop adapter. The correct prop is determined by the application and personal preference. The best way to see the difference is get same diameter props with the same pitch in SF and APC Styles and experiment with both. The SF (those wide bladed) props will produce more thrust. The APC (sleeker looking) will produce more speed. Also use a watt meter to note the differences in amp draw with each.

That's how I look at it. Hopefully the more experienced folks will elaborate and articulate better.

 

[joshuabardwell]

Thanks, everybody. Great answers.

 

[Balu]

It would be nice if someone could put together a "demo chart" showing the different types of props, like I've seen with connectors.