Prop Rip
- Thread starter Twister
- Start date
GaryToland
50cc
Try going up in size like a 30" or 32"
Bartman
Defender of the Noob!
Usually the cure for that sound is a three blade prop as the smaller diameter will have slower tip speeds making for less noise. But you're getting it at half to three quarter throttle. I'm not so sure a larger prop will solve the problem as you'll still have plenty of power to spin it as fast as the other props and do you really want to fly around at an even lower throttle setting? are you hovering at 1/2 throttle?
I'll be curious to see what solves the problem for you.
Bart
I'll be curious to see what solves the problem for you.
Bart
Bartman
Defender of the Noob!
as to why, it's usually because the tips of the props are at or past the point of moving at supersonic speeds. there are other theories about cavitation happening at the tips when you're hovering which is probably true too but it's usually the cracking of the tips moving too fast. smaller diameter three blade props will give slower tip speeds but a larger diameter prop will also help slow things down unless you've got tons of power to spin the larger props just as fast. by going larger you're trying to slow the engine down. larger props require lower RPM's to go supersonic and make that noise. what kind of RPM's do you think you're running at when the noise is happening?
njswede
150cc
Propellers rip because the tips move faster than the speed on sound. In general, a bigger diameter prop is more likely to cause rip. It's fairly easy to calculate the RPM at which a certain prop will rip.
rpm = 255780 / diameter in inches
So a 27" inch prop will rip at 9473 RPM (way above the normal RPM range), but a 32" prop will rip at 7993 RPM, which is easy to achieve in a downline or fast pass.
rpm = 255780 / diameter in inches
So a 27" inch prop will rip at 9473 RPM (way above the normal RPM range), but a 32" prop will rip at 7993 RPM, which is easy to achieve in a downline or fast pass.
TazmanianDevil
Xtreme by DeFinition !
Breaking the speed of sound. It's the supersonic boom.
Not good cause it stales the tips and than the prop it self.
To solve it just put a more bigger Dia prop to make LESS RPM
Not good cause it stales the tips and than the prop it self.
To solve it just put a more bigger Dia prop to make LESS RPM
Kevin-Young
70cc twin V2
When a prop rips it means that the tips of the blades are going supersonic and that is what creates the noise. There are actually several different reasons for this.
The first is the materials that the prop is made of. A lot of wood props will be louder and rip because of the hardness of the wood itself. A laminated wood prop will be better but still will most likely be louder then a carbon fiber prop. One way you can visually see in a wood prop is to take the tips of the prop and try to flex them back and forth. The more they do it the louder then prop is most likely going to be. Carbon fiber props will generally be much stiffer then a wood prop so that is one of the first recommendations when needing a quieter prop.
The second reason is blade design, many props have different blade designs which can lead to higher rpms and in turn more noise. In the case of your Mejzlik 29x10S the S stands for the blade design. The S style blade is a sharper blade style which creates more rpm and again noise.
Another reason is sometimes the prop weight. When the props are really light like the LF versions of Mejzliks there is less of a load on the engine and they can make higher rpm.
If a prop does rip it means that you are actually loosing efficiency so besides the noise issues it is not a good thing for you anyways. Unfortunately props can be a personal preference kind of item because everyone has a slightly different flying style, I guess that is why you see so many different styles of props and brands. The only real solution to finding the best prop for you is trying different ones, unfortunately that can be very expensive and not the most practical thing. Generally if you are ripping the prop the three solutions would be to try a different brand, go to a bigger diameter prop or try a three blade. Going to a bigger diameter will generally bring down your rpm a bit and that should keep you from ripping. With a three blade you are technically loosing a bit of efficiency by adding the third blade so again it will bring the rpm down.
The first is the materials that the prop is made of. A lot of wood props will be louder and rip because of the hardness of the wood itself. A laminated wood prop will be better but still will most likely be louder then a carbon fiber prop. One way you can visually see in a wood prop is to take the tips of the prop and try to flex them back and forth. The more they do it the louder then prop is most likely going to be. Carbon fiber props will generally be much stiffer then a wood prop so that is one of the first recommendations when needing a quieter prop.
The second reason is blade design, many props have different blade designs which can lead to higher rpms and in turn more noise. In the case of your Mejzlik 29x10S the S stands for the blade design. The S style blade is a sharper blade style which creates more rpm and again noise.
Another reason is sometimes the prop weight. When the props are really light like the LF versions of Mejzliks there is less of a load on the engine and they can make higher rpm.
If a prop does rip it means that you are actually loosing efficiency so besides the noise issues it is not a good thing for you anyways. Unfortunately props can be a personal preference kind of item because everyone has a slightly different flying style, I guess that is why you see so many different styles of props and brands. The only real solution to finding the best prop for you is trying different ones, unfortunately that can be very expensive and not the most practical thing. Generally if you are ripping the prop the three solutions would be to try a different brand, go to a bigger diameter prop or try a three blade. Going to a bigger diameter will generally bring down your rpm a bit and that should keep you from ripping. With a three blade you are technically loosing a bit of efficiency by adding the third blade so again it will bring the rpm down.
