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Old 02-06-2013, 08:31 AM
3DHS Trunk-Monkey
Josh Price's Avatar
Arkansas
Joined May 2006
4,300 Posts

correct. the tips of the prop go super sonic. larger props take fewer rpms to cause this and flexable props make it easier as they flex and the motor has less resistance to reach the higher rpms. Below is how to figure tip speed and how to guage what you can do with a motor to prop it correctly. The problem is finding out what the motor is capable of turning with out effecting the spool up time and the rpms to the point it is no longer effective for what we are doing
http://www.pponk.com/HTML%20PAGES/propcalc.html

or

1
Calculate propeller tip speed in miles per hour by multiplying prop diameter, RPM, and the constant 0.002975. For example, 32 inches multiplied by 6,800 RPM and 0.002975 equals 647.36 miles per hour.


2
Calculate the speed of sound for the given ambient temperature by adding 460 to it, taking the square root, then multiplying by 33.4. For 59 degrees Fahrenheit, add 59 and 460 to obtain 519. The square root of 519 is 22.78. Lastly, 22.78 multiplied by 33.4 yields 760.9 miles per hour.


3
Divide the tip speed in miles per hour by the speed of sound. In our example, 618.8 divided by 760.9 gives you a mach speed of 0.813.
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Old 02-06-2013, 08:40 AM
Pro kool aid drinker
dookieshoot's Avatar
Mass
Joined Feb 2010
282 Posts

I love a high speed pass, prop rip, and everything that goes along with it...
But that sound travels a loooooong distance. I think some people here are getting their panties in a wrinkle. It's "suggested" that you guys with them big beautiful planes take others enjoyment into consideration. That's all.

I have to get started building my plane for the Nall, omp hybrid edge. Maybe a couple homebrew foamies as well. If I'm lucky one of you guys will give me a pull on one of your big birds! Can't wait to get there, first time and if we all heed the "suggestion" there will be many more Nalls to come.
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Old 02-06-2013, 09:05 AM
SILVER FOX
wmat7039's Avatar
Acworth GA
Joined Jan 2006
1,555 Posts

Quote:
Originally Posted by Josh Price View Post
correct. the tips of the prop go super sonic. larger props take fewer rpms to cause this and flexable props make it easier as they flex and the motor has less resistance to reach the higher rpms. Below is how to figure tip speed and how to guage what you can do with a motor to prop it correctly. The problem is finding out what the motor is capable of turning with out effecting the spool up time and the rpms to the point it is no longer effective for what we are doing
http://www.pponk.com/HTML%20PAGES/propcalc.html

or

1
Calculate propeller tip speed in miles per hour by multiplying prop diameter, RPM, and the constant 0.002975. For example, 32 inches multiplied by 6,800 RPM and 0.002975 equals 647.36 miles per hour.


2
Calculate the speed of sound for the given ambient temperature by adding 460 to it, taking the square root, then multiplying by 33.4. For 59 degrees Fahrenheit, add 59 and 460 to obtain 519. The square root of 519 is 22.78. Lastly, 22.78 multiplied by 33.4 yields 760.9 miles per hour.


3
Divide the tip speed in miles per hour by the speed of sound. In our example, 618.8 divided by 760.9 gives you a mach speed of 0.813.
We have had this chart made up by George Hicks from Gulfstream in IMAC for MANY years.

Gives a very good indication to pilots.
Wayne
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Old 02-06-2013, 09:06 AM
Fly Hard! Land Soft...
andyjuice22's Avatar
United States, OH, Middleburg Heights
Joined Sep 2012
712 Posts

Quote:
Originally Posted by dookieshoot View Post
I love a high speed pass, prop rip, and everything that goes along with it...
But that sound travels a loooooong distance. I think some people here are getting their panties in a wrinkle. It's "suggested" that you guys with them big beautiful planes take others enjoyment into consideration. That's all.

I have to get started building my plane for the Nall, omp hybrid edge. Maybe a couple homebrew foamies as well. If I'm lucky one of you guys will give me a pull on one of your big birds! Can't wait to get there, first time and if we all heed the "suggestion" there will be many more Nalls to come.
i kinda agree with you it is cool to do a fast and loud pass. but when people do them all day it is just too much noise and people start to complain.
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Old 02-06-2013, 09:43 AM
I WENT ALL IN AT JOE NALL 2013
ken crane's Avatar
SUNNY CAPE COD MA.
Joined Dec 2007
1,602 Posts

Quote:
Originally Posted by andyjuice22 View Post
i kinda agree with you it is cool to do a fast and loud pass. but when people do them all day it is just too much noise and people start to complain.
lol and for you guys that have never been about the 4th day of 7 it gets old no matter how much you love noise !
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Old 02-06-2013, 09:55 AM
Pro kool aid drinker
dookieshoot's Avatar
Mass
Joined Feb 2010
282 Posts

Your absolutely right, it does get old. Rip em up on your home turf is what I should have said, but when at an event with a gagillion people have diligence and respect for your fellow man!

If you guys see a halfa$$ed hybrid with ugly wrinkled covering that'll be me! Come on over and hi!
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Old 02-06-2013, 10:25 AM
RUTNBUC
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United States, SC, McClellanville
Joined Sep 2008
2,608 Posts

I enjoyed the machine gun vs rc plane vid. I would kill, to get to run about 6000 rounds thorugh the minigun. Dillon builds awesome weapons for sure. And the mg42 was bad azz too.
I have flown the DLE 170 on stock mufflers at Joe Nall , no problem. Cause I used the throttle stick with forethought.
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Old 03-20-2013, 08:49 PM
Professor Mike
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United States, VT, Jericho
Joined Oct 2008
683 Posts

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Old 03-20-2013, 10:50 PM
Free Agent
Vital-Rc's Avatar
United States, KY, Glasgow
Joined Oct 2010
1,256 Posts

I prefer prop rip over turbines. Those things give me a head ache after about 5 mins.

ps : imastockmufflerflyer:
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Old 03-22-2013, 05:23 PM
Registered User
United States, GA, Atlanta
Joined Jan 2012
85 Posts

Quote:
Originally Posted by ken crane View Post
one of the issues I have seen in the last 2 years is the 170s and 150s with stock mufflers. some of those are obnoxious. not complaining but its the truth. we had a couple of guys on the 3d line that were asked to finish the day and put those away until they were quieter. had nothing to do with prop rip.

but on the other hand if pat wants people to get quieter I know a great place for some of the quietest and smoothest running cans going...um www.planebenderproducts.com sorry couldn't resist.
Agreed these are great cans! I have them on a couple of my planes and love em.
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Old 03-22-2013, 06:00 PM
3DHS Trunk-Monkey
Josh Price's Avatar
Arkansas
Joined May 2006
4,300 Posts

With out question pro flows are the way to go for cans. I have a set on a 170 and they work great and have a great throttle transition. Pro Flows for the WIN!
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Old 03-22-2013, 06:04 PM
Tail Dragger RC
Spats's Avatar
United States, CA, San Diego
Joined Sep 2012
1,505 Posts

Quote:
Originally Posted by Josh Price View Post
With out question pro flows are the way to go for cans. I have a set on a 170 and they work great and have a great throttle transition. Pro Flows for the WIN!
Hey Josh, what are you bringing to Nall? I am interested in checking out some of the 3DH stuff.
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Old 03-24-2013, 02:14 PM
3DHS Trunk-Monkey
Josh Price's Avatar
Arkansas
Joined May 2006
4,300 Posts

71 slick
89 slick
103 extra
120 lx
126 slick
and then the other guys will have about everything else you might want to see
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Old 03-24-2013, 04:52 PM
Tail Dragger RC
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United States, CA, San Diego
Joined Sep 2012
1,505 Posts

Quote:
Originally Posted by Josh Price View Post
71 slick
89 slick
103 extra
120 lx
126 slick
and then the other guys will have about everything else you might want to see

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