thread6-175834
In Ray W. Prouty', VOL 1 Aeordynamics book Pg 248, he talks about blade twist. He says that there is a nonlinear "ideal twist" which in theory will even up induced velocity distribution. This type of twist to a blade is to difficult to produce. So it is common to have a linear twist. You can get the most efficiency from a negative 20 degree twist. But the first 10 to 12 degrees is the greatest gain in efficiency. Blade twist can give you a five percent increase in figure of merit. This is an increase of about 20 percent payload capability. On the UH-60, we have a negative 18 degree twist. You can also gain another 2 to 4 percent inrease in figure of merit by adding anhedral tips.
In Ray W. Prouty', VOL 1 Aeordynamics book Pg 248, he talks about blade twist. He says that there is a nonlinear "ideal twist" which in theory will even up induced velocity distribution. This type of twist to a blade is to difficult to produce. So it is common to have a linear twist. You can get the most efficiency from a negative 20 degree twist. But the first 10 to 12 degrees is the greatest gain in efficiency. Blade twist can give you a five percent increase in figure of merit. This is an increase of about 20 percent payload capability. On the UH-60, we have a negative 18 degree twist. You can also gain another 2 to 4 percent inrease in figure of merit by adding anhedral tips.