The Tail Rotor
A question for Nick Lappos,
normally we could ask this question on rotorheads, but I didn't want to get swamped with Zuckerisms.
Very little information is written about the tail rotor and its various designs. I have two keepsakes from aircraft ive flown, one is a Bell 206 tail rotor the other is a Fenestron blade from the 365 series. The 206 blade is symetrical, no twist or taper (that I can see) and the wear strips on the edge indicate the speed the outer portion rotates compared to the inner portion. Is this lift difference taken out by flapping? I havn't seen the 206 for a while so my memory is vague, but I am presuming the lead and lag is accounted for in some way, the root has two holes in line with each other to fix it to the tail hub. Or, am I completely wrong and the tail rotor is designed differently because of the short rotor diameter.
The fenestron blade has about 7degrees of twist, and the blade is assymetrical, there is the ability for the pitch to change, but flapping would be nearly totally eliminated. Is this the reason of the two different designs, the ability to flap or in the case of the fenestron, built in twist and assymetrical design.
Ive searched the library at Uni and very little is written about the tail rotor. Ive gone back to my flying experince to track down the reasons behind the designs of tail rotors and fellow pilots seemed to get stumped as well. One helo I noticed with a tapered tail rotor was the S 55 in an old photo, so far, thats the only one. I hope you could enlighten the subject for me. Thanks Nick