Seaplanes Aircraft that typically take off and land on water...radio control seaplane discussions are in here.

prop size

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Old 08-29-2012, 09:24 AM
  #1
m-mtoys
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Default prop size

I am putting a 55 AX engine on this plane,but not sure what prop to use in a 3 blade or 4 blade.

The engine calls for a 12/7 or 8 13/6or 7 Not space for a two blade prop. Carey
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Old 08-29-2012, 02:26 PM
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Default RE: prop size

Use the same pitch for a 3-blade and drop the diameter by 10%
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Old 08-29-2012, 03:27 PM
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Default RE: prop size

Had no idea they are making 4 bladed props.
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Old 08-30-2012, 01:58 AM
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Default RE: prop size

Biela makes 2, 3, and 4 blade props in many different size/pitch combinations. They also have some pusher props. The material is carbon fiber with a wood hub. All the props are balanced individually just before they are put out for sale.

In the interests of full disclosure: I do not work for Biela, nor do I receive anything from them for any sales that they may get from my comments.
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Old 09-12-2012, 11:30 AM
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Default RE: prop size

Hi!
What kind of strange animal is it that cannot take a two blade prop??
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Old 09-13-2012, 04:39 AM
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11 x 7 three blade
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Old 09-13-2012, 01:31 PM
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Default RE: prop size

It is a Balsa USA Laker plane
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Old 09-13-2012, 03:41 PM
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Default RE: prop size

What's the biggest prop you have room for?

I have a pair of 55AXs on a B-25. I finally settled on 12x6 MAS 3 blade props. These let the engines turn about 10,500 rpm on 15% Cool Power, good for around 60 mph and gobs of thrust. They never liked any of the various two blade props I tried, including the ones recommended by OS.
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Old 09-14-2012, 03:17 AM
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Default RE: prop size

Hi!
I'm certain that if you tried some Graupner Sonic or RAM...or even APC props in the range of 12x6,13x4, 13x5 you would see better performance than those 12x6 3-blade MA props.
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Old 09-14-2012, 06:54 AM
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Default RE: prop size

It's hard to find a lot of info on the Laker, it's an old Laddie Mikulasko design from RCM Magazine. The listing on RCM plans calls for a 40-46, and I'd bet that Laddie put that engine pod down low so that an 11" prop is probably as big as you can go.

You might want to think about a 46AX, or even electric power. I used a Turnigy G46-670 turning an MAS 11x7 3 blade on five cells in a Mikulasko "Arrow" flying boat, and it wails. The nice thing about electrics in "pod engine" flying boats is that the battery pack makes it a lot easier to balance the dang things. They really want to come out tail heavy.
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Old 09-14-2012, 07:12 AM
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Default RE: prop size


Quote:
ORIGINAL: m-mtoys

I am putting a 55 AX engine on this plane,but not sure what prop to use in a 3 blade or 4 blade.

The engine calls for a 12/7 or 8 13/6or 7 Not space for a two blade prop. Carey
If there was no modification done to the kit, then 12” prop will fit nicely. The model does not need any larger props.
Laddie.
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Old 09-14-2012, 09:22 AM
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Nice to hear from the source!!


I'd go with the 12x6 MAS 3 blade, then. I find that the 55s in my bomber run a very long time on 11 oz of fuel with that prop.
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