prop ?
- Thread starter littleT
- Start date
I'm a dealer for whirlwind. I have had the same problem on a 400 chevy DD, no mater what degree I set it at it was very loud. I don't know what you have it on, but i found out they are very loud and don't perform as well on a DD. They do very well on belt or gear boxes. I think this has to do with the length of the prop. If you are DD or aircraft the super snapper or whisper tips work a lot better.
CactusJack
Well-known member
Do you know what RPM it is spinning at? Probably anything over about 3500 rpm the tips are goung thru the sound barrier? A good way to tell with prop noise if the sound comes back as an echo as well, generally the tips are thru the barrier.
Thats why DD aeroplanes have such slow revving engines, funny things happen to props run too fast
I just reread you post, a 72" prop is probably too fast at 2900 - 3000, IMO, you need a reduction drive or a smaller diameter prop..... damage to the prop will probably occur if you keep running it too fast & it will become less efficient too. If you have a thrust gage (scales) you can run the motor and check the thrust output, you will probably find that when the prop gets noisy the thrust will not increase, and may in fact reduce thrust until you back off to where the prop tips come back under the barrier. If you have a tacho, about 200 rpm under the rpm when the prop goes noisy, is the place max rpm (for the prop) should be.
Does the manufacturer have a listing for the max rpm for that prop? If not, find out... its important
Thats why DD aeroplanes have such slow revving engines, funny things happen to props run too fast
I just reread you post, a 72" prop is probably too fast at 2900 - 3000, IMO, you need a reduction drive or a smaller diameter prop..... damage to the prop will probably occur if you keep running it too fast & it will become less efficient too. If you have a thrust gage (scales) you can run the motor and check the thrust output, you will probably find that when the prop gets noisy the thrust will not increase, and may in fact reduce thrust until you back off to where the prop tips come back under the barrier. If you have a tacho, about 200 rpm under the rpm when the prop goes noisy, is the place max rpm (for the prop) should be.
Does the manufacturer have a listing for the max rpm for that prop? If not, find out... its important