Is it posible to rip the prop with a 50cc motor

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Sly3D · 07-03-2009, 11:11 PM

I'm just wondering because it sounds so cool. For thoose of you who don't know what prop ripping is, its when you prop spins at a certain rpm and breaks the sound barrier.

octanehuffer · 07-04-2009, 12:10 AM

Prop rip is ineffecient and means that you have the wrong one installed. It is the air being blown away from the leading edges of the prop tips. Thus creating innefiency. If you want to create prop rip on your 50cc, install a prop with little load. A 22x1 should do it.

notorious_benny · 07-04-2009, 12:22 AM

It dosnt happen from your prop breaking the sound barrier, it happens when the prop gets up to around Mach 0.6 or so.

150cc class props do not break the sound barrier on our aerobatic models.

octanehuffer · 07-04-2009, 12:55 AM

Good point? But then why all the noise?

harv · 07-04-2009, 01:02 AM

From what ive ehard its from engines with larger props. Larger props tend to be the ones that rip. THe tip speed spins o fast it hits supersonic speeds. but im not sure what actually causes the sound. Prop vibration? i dunno. id like to know the real answer also.

notorious_benny · 07-04-2009, 02:08 AM

The tips on a 32 inch prop will hit 340m/s (speed of sound) at 8100rpms.

28 inch prop needs to be spinning at 9270 rpms to reach 340m/s

22 inch prop needs to spin at 11790 rpms.

As the prop becomes trans sonic the air flowing around the prop can reach higher and lower velocities. The noise is from the interaction of the air flowing over the prop.
I cannot offer a better example, but I can say that the prop certanly does not need to be going supersonic to 'rip'. Better prop design leads to better efficiency at higher tip speeds. These props will also be quieter.

reyn3545 · 07-04-2009, 06:58 AM

So, as a prop rips, does it lose efficiency, or is it just noisy? I had a biplane with a 3W 170, it ripped a 32x10 prop really loud, but it seemed like it flew well. I put a 32x12 on it, the ripping went away unless I really dove at full throttle, but I don't think the plane flew as well as it did with the 32x10.

3ddd · 07-04-2009, 09:21 AM

look at an airplane wing,the air moves faster over the more curved side and makes lower pressures,the top. look at your prop,the air moves faster over the curved side lower pressures,the front,when the air meets at the trailing edge again it is spoiled and does no good, they hit together hard and make the ripping sounds, just my 2 cents

RadiaLars · 07-04-2009, 10:14 AM

Yes.
A DL50 spinning a vess 23a-23b will rip.

askforplanes · 07-04-2009, 10:34 AM

A higher diameter and lower pitch will have the bast chance at ripping, but the high rpm are not great for the engine.

JP

askforplanes · 07-04-2009, 11:21 AM

To find the tangential (tip) velocity (in fps) take the radius of rotation (radius of the prop) r, times the RPM, and take the answer and divide it by 9.55.

[(r)x(RPM)]/9.55

JP

Sly3D · 07-04-2009, 05:50 PM

	Quote: Originally Posted by RadiaLars
	Yes. A DL50 spinning a vess 23a-23b will rip.

With what muffler or can? Do you have a DL50 that rips?

scott m lyons · 07-04-2009, 07:54 PM

Who's field are you trying to shut down? Your's?

Paul5992 · 07-04-2009, 08:06 PM

	Quote: Originally Posted by scott m lyons
	Who's field are you trying to shut down? Your's?

I fly out in the country. If you rip down town metropolis you will probably get shut down. But that isn't what he asked...

My DL-50 spins a 22X8 Xoar at 7650rpm. And yes it does rip it. It's not as loud as my 27X10 on my DA-100 but it's ripping.

cesar781 · 07-04-2009, 09:34 PM

VESS PROP IS GOOD FOR IT

07-03-2009, 11:11 PM	#1
Sly3D Bad-ass Super Contributer! Join Date: Apr 2009 Location: Woodland Hills CA Age: 16 Posts: 971	Is it posible to rip the prop with a 50cc motor I'm just wondering because it sounds so cool. For thoose of you who don't know what prop ripping is, its when you prop spins at a certain rpm and breaks the sound barrier. __________________ AeroWorks 35% Extra 260-DA100 JR X9503 2.4 DSM2

07-04-2009, 12:10 AM	#2
octanehuffer Bad-ass Super Contributer! Join Date: Jan 2007 Location: Lakeland, Minnesota Age: 31 Posts: 847	Re: Is it posible to rip the prop with a 50cc motor Prop rip is ineffecient and means that you have the wrong one installed. It is the air being blown away from the leading edges of the prop tips. Thus creating innefiency. If you want to create prop rip on your 50cc, install a prop with little load. A 22x1 should do it. __________________ This space for rent

07-04-2009, 12:22 AM	#3
notorious_benny IMAC wannabe! Join Date: Jan 2006 Location: Griffith, NSW, Australia Age: 31 Posts: 3,374 Awards Showcase Total Awards: 1	Re: Is it posible to rip the prop with a 50cc motor It dosnt happen from your prop breaking the sound barrier, it happens when the prop gets up to around Mach 0.6 or so. 150cc class props do not break the sound barrier on our aerobatic models. __________________ Look out Ulimited in 2011!!!

07-04-2009, 12:55 AM	#4
octanehuffer Bad-ass Super Contributer! Join Date: Jan 2007 Location: Lakeland, Minnesota Age: 31 Posts: 847	Re: Is it posible to rip the prop with a 50cc motor Good point? But then why all the noise? __________________ This space for rent

07-04-2009, 01:02 AM	#5
harv it wont go any lower Join Date: Feb 2006 Location: Canada Eh? Age: 19 Posts: 2,369	Re: Is it posible to rip the prop with a 50cc motor From what ive ehard its from engines with larger props. Larger props tend to be the ones that rip. THe tip speed spins o fast it hits supersonic speeds. but im not sure what actually causes the sound. Prop vibration? i dunno. id like to know the real answer also. __________________ Borderline IMAC Team Aztech Aero Smart-Fly

07-04-2009, 02:08 AM	#6
notorious_benny IMAC wannabe! Join Date: Jan 2006 Location: Griffith, NSW, Australia Age: 31 Posts: 3,374 Awards Showcase Total Awards: 1	Re: Is it posible to rip the prop with a 50cc motor The tips on a 32 inch prop will hit 340m/s (speed of sound) at 8100rpms. 28 inch prop needs to be spinning at 9270 rpms to reach 340m/s 22 inch prop needs to spin at 11790 rpms. As the prop becomes trans sonic the air flowing around the prop can reach higher and lower velocities. The noise is from the interaction of the air flowing over the prop. I cannot offer a better example, but I can say that the prop certanly does not need to be going supersonic to 'rip'. Better prop design leads to better efficiency at higher tip speeds. These props will also be quieter. __________________ Look out Ulimited in 2011!!!

07-04-2009, 06:58 AM	#7
reyn3545 Bad-ass Super Contributer! Join Date: Oct 2006 Location: Alpharetta, GA Age: 52 Posts: 5,510	Re: Is it posible to rip the prop with a 50cc motor So, as a prop rips, does it lose efficiency, or is it just noisy? I had a biplane with a 3W 170, it ripped a 32x10 prop really loud, but it seemed like it flew well. I put a 32x12 on it, the ripping went away unless I really dove at full throttle, but I don't think the plane flew as well as it did with the 32x10.

07-04-2009, 09:21 AM	#8
3ddd tissue ? cry baby jack wagon! Join Date: Jan 2006 Location: pyote,texas Age: 58 Posts: 2,651	Re: Is it posible to rip the prop with a 50cc motor look at an airplane wing,the air moves faster over the more curved side and makes lower pressures,the top. look at your prop,the air moves faster over the curved side lower pressures,the front,when the air meets at the trailing edge again it is spoiled and does no good, they hit together hard and make the ripping sounds, just my 2 cents __________________ Life's journey is not to arrive at the grave >safely and in a well preserved body,but rather to skid in > sideways,totally screwed up,worn out,shouting,"oh damn what a fine ride! AMA 98634 > HEY I GOT A DIVORCE----HELL YEA > Futaba, FROMECO:a good way to get a charge out of life,,3w all the way for a good day

07-04-2009, 10:14 AM	#9
RadiaLars Uber Contributer Join Date: Sep 2008 Location: Norway Posts: 157	Re: Is it posible to rip the prop with a 50cc motor Yes. A DL50 spinning a vess 23a-23b will rip.

07-04-2009, 10:34 AM	#10
askforplanes 3D Giants Join Date: Dec 2007 Location: Virginia Age: 17 Posts: 1,066	Re: Is it posible to rip the prop with a 50cc motor A higher diameter and lower pitch will have the bast chance at ripping, but the high rpm are not great for the engine. JP __________________ http://www.jandjmodelaircraftcompany.com/

07-04-2009, 11:21 AM	#11
askforplanes 3D Giants Join Date: Dec 2007 Location: Virginia Age: 17 Posts: 1,066	Re: Is it posible to rip the prop with a 50cc motor To find the tangential (tip) velocity (in fps) take the radius of rotation (radius of the prop) r, times the RPM, and take the answer and divide it by 9.55. [(r)x(RPM)]/9.55 JP __________________ http://www.jandjmodelaircraftcompany.com/

07-04-2009, 07:54 PM	#13
scott m lyons GOT GAS ? Join Date: Aug 2008 Location: Bennington VT. Age: 34 Posts: 4,199	Re: Is it posible to rip the prop with a 50cc motor Who's field are you trying to shut down? Your's? __________________ save a plane......fly futaba !

07-04-2009, 09:34 PM	#15
cesar781 Bad-ass Super Contributer! Join Date: May 2007 Location: Brazil, São Paulo, Jales Posts: 306	Re: Is it posible to rip the prop with a 50cc motor VESS PROP IS GOOD FOR IT

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