Originally Posted by
JohnDixson
Thanks,rrekn,that pic reminded of something: one of the plans for the S-67 future,was to reinstall the fenestron tail we had already flown on it,but adding both a controllable rudder and a declutch mechanism for the fenestron rotor.
Historical note re the S-67 fenestron. The highest speed I see quoted for the 67 happened by coincicidence with the fenestron test program.The high speed limit was 200 Kias but on that day ( it was winter, cold and somewhat turbulent due to a just passed cold front ) we did it around 6000 ft and were watching the tip path closely, remembering that the standard rotor on the S-61F had gone unstable at a Mtip of .94 ( freestream ). That day the 200 KIAS resulted in a freestream Mtip of .96 and without any rotor stability issue.
I've always liked the S-67 and I think Bell did a good job hitting it with the "shrink ray" with the Model 360... not an unreasonable configuration for the mission. Did the S-67 have the ability to slow down the rotor rpm to control tip speed? Or at ~200 knots, was it at the limits of the system's ability to do so?