Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Anyone using one bladed props?

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Old 07-09-2007, 12:15 PM
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Flying freak
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Default Anyone using one bladed props?

Hi,

Is anyone using one bladed props With a counter balance we all know that the more blades = less effecient so are any of you trying out the single bladed stuff?

If so were do you get these props?

Steven
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Old 07-09-2007, 01:04 PM
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Default RE: Anyone using one bladed props?

Only heard of it for control line speed contests. I think Bolly offers these, at least on their website.

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Old 07-09-2007, 01:31 PM
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Default RE: Anyone using one bladed props?

I spotted this little jewel at the Revver Brotherhood assembly last year. The SoCal lekky speed guys get it on for sure!
When I asked the owner of the model he mentioned they came from Australia. Hunt down Troy-RCU here in the forum, he was tight with those guys.
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Old 07-09-2007, 02:54 PM
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Default RE: Anyone using one bladed props?

That's right - Bolly is located in Australia. Here is the link:

http://www.bolly.com.au/models/glassone.html

Smok
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Old 07-09-2007, 03:22 PM
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Default RE: Anyone using one bladed props?

....them So. Cal. lekky guys are some fast dudes....
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Old 07-09-2007, 04:22 PM
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Default RE: Anyone using one bladed props?

That's cuz they're all amped up!
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Old 07-09-2007, 05:25 PM
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Default RE: Anyone using one bladed props?

That was my prop and I got it at supercoolprops.com
They make a lot of noise and go very well.

Mark
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Old 07-10-2007, 02:27 PM
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Default RE: Anyone using one bladed props?


ORIGINAL: MarkF

That was my prop and I got it at supercoolprops.com
They make a lot of noise and go very well.

Mark
I cant find it on there site am i missing somthing ???
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Old 07-10-2007, 02:52 PM
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Default RE: Anyone using one bladed props?

I see it here http://supercoolprops.com/price_list2.php under F5D.

Blessings, Terry
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Old 07-10-2007, 07:11 PM
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Default RE: Anyone using one bladed props?

I have heard [only heard] that the vibration from a single blade [no matter how well ballanced or phased] is terrible.
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Old 07-10-2007, 08:46 PM
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Default RE: Anyone using one bladed props?

The issue is asymmetric thrust which the designers usually have to make provisions for; ie putting the weight a little forward of the blade so centrifigal force tries to counter the offset thrust from the blade. The other issue is to get the dynamic balancing correct. The center of mass needs to be equal for both sides or it'll balance statically but vibrate like crazy revved up. We haven't had any issues with Supercool's props.
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Old 07-10-2007, 10:02 PM
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Default RE: Anyone using one bladed props?

Troy, That is really great news, I always thought 1 blade was a dead issue for RC because of the bad vibes.
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Old 07-11-2007, 12:03 AM
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Default RE: Anyone using one bladed props?

I have tried some Eliminator single blade props on 1/2a engines with good results. They certainly rev like crazy.


Chris
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Old 07-11-2007, 11:35 AM
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Default RE: Anyone using one bladed props?

id be tempted to try on a jett 50 fire and a gp viper any ideas on what size i weould need??
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Old 07-12-2007, 11:32 AM
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Default RE: Anyone using one bladed props?

You can generally go up in 'relative' diameter to make up for the missing blade area from the other side, but it's an undertaking of machining to do it right and it's a bit of liability to make sure you don't fling something. I've made my own in the smaller 5" range of props and it was a bit of tinkering and a lot of balancing to get it to run well. Supercool's are pretty cool in that the blade 'keys' into the counterbalance so it can't shift. It's also mass balanced pretty well. I have no machining talents so I do it the cave-man way and just make it work.

The real advantage of a single blade, at least on smaller props, is that you can increase the chord length of the prop thus increasing the reynolds numbers and in the end increasing efficiency of the blade. The small props operate in pretty low reynolds numbers unless you spin the heck out of them. Increasing the chord length on a 2-blade will do the same but the load on the motor goes way up. So, transferring the surface area to one blade and then making it balanced makes it one efficient blade instead of two so-so blades (technical term). There are other theories on vortices and prop wash but I think it's the chord length that gives you the boost in efficiency.

Originally I made mine from my standard 2-blader with a blade cut off but it didn't make any real gains. In fact, it had worse acceleration. That's when I realized I needed to go to a bigger prop and then trim down diameter to increase the area. It worked OK but I never really did enough scientific testing or pylon raced it against the clock.

I don't know if I'd recommend it on a Jett .50 unless you are certain you know what you're doing. If anything flies off in testing or in the air it could be disastrous.
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Old 07-12-2007, 03:59 PM
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Default RE: Anyone using one bladed props?

I blew over half of one blade off on a Formula One (ST X-40 powered) during the engine start/runup. The vibration remained constant, while the rpm went up about 1000. I was in a contest heat, so I went ahead and flew it rather than take a zero. The airplane turned a time around 4 seconds faster than it's normal heat time, which was a lot of improvement.

These engines are not that well balanced in the first place. I was lucky that the prop was phased to the crank counter balance to handle the weight shift.
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Old 07-12-2007, 06:38 PM
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Default RE: Anyone using one bladed props?

I blew 1/2 of one blade off a Fora powered 1/2A speed plane [in flight] and it was like the plane shifted into over drive. I didn't realize what had happened until after the plane landed. I refueled it and flew it again, eventually snapping off the other blade during a landing. I haven't tried to duplicate the 1.5 blader, but what snapped off was almost zero weight.....so the vibration didn't seem too bad.
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Old 07-15-2007, 01:06 PM
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Default RE: Anyone using one bladed props?

Now that's crazy!
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