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Old Nov 06, 2013, 02:32 PM
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Originally Posted by Taurus Flyer View Post

So NOT Chill, but nobody noticed!

Taurus Flyer
APC claims their safe range is higher than MA, all I did was use the number they suggest for their nitro props... 190,000 RPM*Inches / 12 Inches = 15,833 RPM.
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Old Nov 06, 2013, 02:41 PM
I bail out, anywhere, anytime
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Quote:
Originally Posted by ChillPhatCat View Post
APC claims their safe range is higher than MA, all I did was use the number they suggest for their nitro props... 190,000 RPM*Inches / 12 Inches = 15,833 RPM.



After reading post 1,

http://www.rcgroups.com/forums/showp...44&postcount=1

For "Old School" there is one thing to do,

http://www.rcgroups.com/forums/showp...87&postcount=2



DUNNING KRUGER!
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Old Nov 06, 2013, 02:49 PM
Fueled by Arabica Beans
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I have no idea what you are trying to say.
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Old Nov 06, 2013, 02:52 PM
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Quote:
Originally Posted by ChillPhatCat View Post
I have no idea what you are trying to say.
That's the Dunning Kruger effect!
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Old Nov 06, 2013, 02:54 PM
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Originally Posted by Taurus Flyer View Post
That's the Dunning Kruger effect!
So you think you are smarter than you actually are?
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Old Nov 06, 2013, 02:58 PM
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Again,



Quote:
Originally Posted by ChillPhatCat View Post
Props only cost a few bucks each... not sure why you're giving him a hard time Taurus. Even with a 12x4 spinning at 12,8k on the ground he will still probably see 45-50 mph, which is plenty of speed to keep it in the air... he might find a 12x5 is a better prop on the .55, which will be even better for flying speed.
TF
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Old Nov 06, 2013, 03:40 PM
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until you(TF) come up with some actual evidence too the contrary, you are looking like a "TROLL"!

the guy is just posting what he has done, if you don't agree, you might want too do some research of your own, rather just making a lot of noise!

a prop manufacturer, will not post, the actual RPM's at which there props will explode! that is the rpm they will warrenty them too!

I have taken many an auto well past the bottom of the speedometer, and they did not blow up! just saying! a few hundred rpms over what the maker says the prop will do, is a guide line, not the LAW!
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Old Nov 06, 2013, 03:46 PM
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Originally Posted by whiskykid View Post
until you(TF) come up with some actual evidence too the contrary, you are looking like a "TROLL"!

the guy is just posting what he has done, if you don't agree, you might want too do some research of your own, rather just making a lot of noise!

a prop manufacturer, will not post, the actual RPM's at which there props will explode! that is the rpm they will warrenty them too!

I have taken many an auto well past the bottom of the speedometer, and they did not blow up! just saying! a few hundred rpms over what the maker says the prop will do, is a guide line, not the LAW!
Whe not only have to do with the prop manufacturer, read my post 2!!
TF
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Old Nov 07, 2013, 07:01 AM
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Ok, enough derailment of this thread, I'm still interested to hear what numbers you get from those .55's, please share when you get them. Also, after a little thought I don't see anything wrong with using even a 12" MAS prop at 13k on the ground... in the air it will unload a little, but I don't think it will actually put the prop in danger... if you assume they used even a slim factor of safety of 1.2 to come up with that number, that prop can take 16,500 RPM (just make sure its well balanced).

As I pointed out of course, APC has a higher claimed RPM range, so that would be an even more solid bet for a 13k+ 12" prop... and my calculations show that the tips are certainly not even approaching the speed of sound at 16k RPM ~ 571 mph.
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Old Nov 07, 2013, 08:39 AM
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Quote:
Originally Posted by ChillPhatCat View Post
Ok, enough derailment of this thread, I'm still interested to hear what numbers you get from those .55's, please share when you get them. Also, after a little thought I don't see anything wrong with using even a 12" MAS prop at 13k on the ground... in the air it will unload a little, but I don't think it will actually put the prop in danger... if you assume they used even a slim factor of safety of 1.2 to come up with that number, that prop can take 16,500 RPM (just make sure its well balanced).

As I pointed out of course, APC has a higher claimed RPM range, so that would be an even more solid bet for a 13k+ 12" prop... and my calculations show that the tips are certainly not even approaching the speed of sound at 16k RPM ~ 571 mph.
Here is all we have tested since the installation of the .55 on the Cessna, and a comparison with those two props when powered by the .46:

.46 AXII .55 AX MAX

12x6 3blade Master Airscrew 9,500 rpm 6lb5oz 11,100 rpm 8lb3oz
12x4 2blade Master Airscrew 12,800rpm 8lb6oz 13,300 rpm 8lb9oz

Ooops, the columns don't line up on the post, but data to the right side are the .55 results for the blades tested.
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Old Nov 07, 2013, 08:47 AM
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That's a pretty good increase with the 3 blade prop... comes out to 63mph pitch speed too... assuming the unloading of the prop negates the inefficiency of "real air", there shouldn't be a concern of not being able to get to flying speed.
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