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"RC Speed Boat Power Drive TD .020"

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Post  EXModelEngines Wed Oct 21, 2020 9:04 am

We are looking for opinions regarding 5x3 3-blade props in the event we were to move to producing these. Is there a consensus if it be more advantageous to have the recessed hub or the later version more common to other propellers? These would be RH regardless of hub design.

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Post  balogh Wed Oct 21, 2020 11:38 am

Matt there was a demand for these 5x3 3 bladed RH props on ebay after you and Bernie discontinued to carry them, so I think they will sell well if you start producing them. I have a few brand new ones and I like the look and despite some say the 3 blades are only causing unwanted turbulence for each other and are hence are less efficient than the 2 bladed ones, I like their performance. They are not simple to balance though so a strict manufacturing tolerance like the APC props is more than welcome. The recessed hub with flat face better suits the aluminum spinners than the semi-hollow hub, that is also prone to lose its roundness and may lead to impaired balance.
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Post  EXModelEngines Wed Oct 21, 2020 1:36 pm

balogh wrote:Matt there was a demand for these 5x3 3 bladed RH props on ebay after you and Bernie discontinued to carry them, so I think they will sell well if you start producing them. I have a few brand new ones and I like the look and despite some say the 3 blades are only causing unwanted turbulence for each other and are hence are less efficient than the 2 bladed ones, I like their performance. They are not simple to balance though so a strict manufacturing tolerance like the APC props is more than welcome. The recessed hub with flat face better suits the aluminum spinners than the semi-hollow hub, that is also prone to lose its roundness and may lead to impaired balance.

Thanks for the input....appreciated!
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Post  crankbndr Wed Oct 21, 2020 4:00 pm

I think Cox recessed those props so the plastic spinner pushed in and held the spinner on on some models. No need now IMHO.

PS It didn't work well.
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Post  Mark Diedrichs Wed Oct 21, 2020 5:21 pm

Hey Happy people, Maybe the prop rod folks would be interested. Just say'in. Mark
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Post  balogh Wed Oct 21, 2020 5:23 pm

I guess those in the prop rods are pusher props?
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Post  Mark Diedrichs Wed Oct 21, 2020 5:40 pm

I don't know the correct prop setup, however the prop can be flipped over to provide forward/rearward thrust in the intended direction. Mark
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Post  getback Thu Oct 22, 2020 8:41 am

For reference Mark that want work on a prop rod i tried it and not enough force of air . Matt what would bee the minimum you would have to have made , i don't think anything over 200 would bee feasible . Pumpkin
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Post  EXModelEngines Thu Oct 22, 2020 8:56 am

getback wrote:For reference Mark that want work on a prop rod i tried it and not enough force of air . Matt what would bee the minimum you would have to have made , i don't think anything over 200 would bee feasible . Pumpkin

Yes, they are RH props, but as other have mentioned they are reversible. It would have to be a minimum run of 1000 pieces.
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Post  crankbndr Thu Oct 22, 2020 9:43 am

Reversing a prop will not make it a pusher, reversing engine rotation will.
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Post  944_Jim Thu Oct 22, 2020 9:52 am

Maybe I misunderstand the intent of flipping the prop.

Consider where the thrust bearing is needed.
The block bushing side of the crank throw "thrusts" against the block, and the engine goes forward (pulls, like common airplane).
Or the prop plate "thrusts" against the block snout, and the engine goes backwards (pushes,.like PropRod)

Flipping the prop while maintaining the same crank rotation will only affect the thrust developed. Ensure the "leading edge" of the prop is actually the leading edge for max thrust. Flip the prop to reduce thrust (training mode).

Switching from LH to RH props (while maintaining same crank rotation direction) affects which block surface is the "thrust bearing," and makes the engine switch from push to pull,.or pull to push.

Running the engine in the other direction (while maintaining same prop) will change the direction of thrust. Leave the prop alone for minimal thrust, since the trailing edge is now "leading," or reverse the prop to re-postition the leading edge to maximize thrust. Recognize this affects the crank loads/face bearing the load against the crank.

The point of having two different prop rotations allows for maintaining the preferred thrust bearing surface/engine direction...either pusher or puller configuration.

Right?
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Post  crankbndr Thu Oct 22, 2020 11:52 am

Thats the way it works, a pusher needs a washer to prevent wear on case nose.
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Post  stuntflyr Sat Nov 07, 2020 9:52 pm

I like the props that were flat plate mount with thin, non-safety tips. They made my Guillows Mosquito haul ass!
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Post  944_Jim Sun Nov 08, 2020 7:27 am

Chris,
Any chance you have pics of the Mossie?
Did you use .020s or .049s?
I am a fan of that airplane.
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