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16X8 or 18X10 Biela Wide Blade? RCV 120SP

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Old 02-28-2011, 07:40 PM
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mimoore67
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Default 16X8 or 18X10 Biela Wide Blade? RCV 120SP

Help!

Like Schultz "I know nothing!" (Hogans Hero's reference) - However I do have years of experience with "Normal" four strokes mainly 91's and 120's O.S. surpass.

I am finally building my dream plane a P51 with a "four" blade prop. Over the years I have been acquiring RCV SP engines and now I am going to put my RCV 120SP in a ESM P51B with the Keleo "Scale" exhaust.

QUESTION - I am having a spinner cut and not having any experience, should I go with the 16X8 or 18X10 on the 120SP? I know RCV recommends the APC 15.5 X12 but that prop is "UGLY" and won't go on any MUSTANG of mine! Plus it looks like it would cut you sitting still!

Thanks

http://www.smigla.com/english/four-blade.html
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Old 02-28-2011, 07:51 PM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP

I don't think the 16x8 will have enough pitch. At the lower prop rpm that the RCV turns, you'll need more pitch. I would guess a 16x12 would be more appropriate. I seem to recall reading in either their documentation, or on their RCU support forum, that they don't recommend anything less than a 10 pitch.

Scott
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Old 02-28-2011, 08:03 PM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP

Thanks Scott, for your reply!

I guess for now I'll just have to try the 18X10 and see what kind of RPM's and thrust! The next size would be a 20X10! I read over on the thread where the guys built there own scale prop hubs where were swinging 18X10's - three blades, with the RCV 90SP!
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Old 03-01-2011, 10:13 AM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP

I think one of the problems I had with the 120SP's was not enough load running the 15.5" x 12" APC prop.

Having set up a 61SP in a small Sea Fury, I ran it at 4.2K rpm swinging a 15.5x12 four blade, which surprised the %^&$ out of me.

This prop has since been trimmed to 14" and flown, spinning at 4.8K rpm. 

So I think the 120SP might surprise you on what it can actually spin.
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Old 04-27-2011, 12:39 AM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP

Hey guys!

I´m currently assembling the 1/7 top flite p51 mustang arf, and jut managed to squeeze in the rcv 120 sp engine...

I intend to fly a 4 blade prop (www.ramoser.de), with a diameter of 16,6 inches, and a pitch of 12...(you can set the pitch of these props yourself, so no need to buy 5 different props, wich is quite handy!)
see the last page of (http://www.rcuniverse.com/forum/m_7520206/tm.htm) for some pictures (18.6 inch blades installed here...)

This prop would give me around 10 lb of thrust, and a speed of 60 miles/h according to the thrust hp software...

I will testfly it first with a standard two bladed 18x12 prop, to get familiar with the handling of the mustang however...

I will post again when I have more information on real rpm´s from the engine when I find the time to test it...

Regards,

Jens
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Old 12-05-2011, 01:52 PM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP

Mimoore67, What ever happened.. I want to do the 4 bladed also on my F4U what static thrust and rpm did you get.

Jens, what did you come up with.

It seems static thrust on these engines cant use "normal" 4 stroke static thrusts to compare.. being such a different animal.. this is really necessary to see what has worked best in the past.

Thanks, Nickel
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Old 12-05-2011, 04:26 PM
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Default RE: 16X8 or 18X10 Biela Wide Blade? RCV 120SP


Quote:
ORIGINAL: Ice5

Mimoore67, What ever happened.. I want to do the 4 bladed also on my F4U what static thrust and rpm did you get.

Jens, what did you come up with.

It seems static thrust on these engines cant use ''normal'' 4 stroke static thrusts to compare.. being such a different animal.. this is really necessary to see what has worked best in the past.

Thanks, Nickel
Well, it's still in the box waitings it's turn someday! Right now working on building a new workshop in the garage, as I got booted out of the basement so my kids could have a play room! I'll have a 10x14 room, once I build a wall and insulate/drywall! Hopefully over the holidays I can throw that up!
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