hub question
 

I've been flying planes and helis for 15 years and have a full understanding of them , but I need a new challenge I NEED TO BUILD AUTOGYRO!! First ?- why on the hub do the blades need to flex. question 2- will 1 inch wide blades work on this ? I have charts and graphs on disk loading but this question is'nt answered . The whole idea is that I want to build a .25 size profile autogyro:D

RE: hub question
 

Hi,

If you want a challenge, autogyros will provide that! I don't know the weight, but if you build a .25 size you should use 1-3/4 or 2" wide blades. The length will depend on the weight and the blade profile that you use. I recommend that you use the SG6043 blade profile as they seem to provide the best lift.

The blades need to flex to create a coning angle which acts like diahdral in a wing and also allows the advancing blade to flex up more than the retreating blade.

Phil

RE: hub question
 

Hello Phil and evikfkr....

The really good airfoil is the SG6042. The 6043 has about the same profile but is thicker. When we did the wind tunnel tests, the 6043 didn't provide as much lift as the 6042. I think it has something to do with the greater profile drag of the 6043. HOWEVER, I would bet that for a very light, small autogyro with a slow rotating rotor, a thicker airfoil would work better. It's all a question of the L/D at the operating air velocity of the aircraft.

Bill

RE: hub question
 

Thanks guys!:D

RE: hub question
 

Hi Bill,

I tried to type 6042. However, according to my calculations, I was still 99.98345% correct which is much better than my success with gyros.

Phil

RE: hub question
 

Is there a preferred wood to build a hub with?

RE: hub question
 

I have found the aspect ratio of Gyro blades should be about 10 to 12 that is the ratio between length and chord. They flex up on plastic hinges to compensate for the unequal lift between the advancing & retreating blades. A very flat bottom clark Y section works perfect, for a .25 size engine gyro the rota loading should be about 2.5 ounces psqft.