Originally Posted by
FH1100 Pilot
I literally laughed when I saw that Leonardo had ditched the 609's engine/proprotor configuration and went with fixed-mounted engines for the new NGCTR model. I laughed again when I saw that they ditched the t-tail empennage for that hideous and draggy-looking v-tail setup. Obviously, they learned a bit after that terrible 609 accident TEN YEARS AGO that was attributed to a roll/yaw coupling and the inability of the onboard computers to effectively deal with it. But wait- doesn't the V-tail Beechcraft Bonanza also have a weird and uncomfortable yaw coupling in turbulence, which resulted in Beech switching back to a conventional tail for the stretched Bonanza (A-36)? 609 pilots are probably going to be told that hand-flying in high-speed cruise is PROHIBITED, and if the autopilot kicks off for any reason in turbulence, you're probably all going to die.
Back to the 609... It has sure been quiet on that front...so quiet that it makes me wonder if Leonardo has given up on the design and transferred all of the important technical people over to the NGCTR program. I mean, after all, it was back in 1957 that Bell began playing with the idea of a tilt-rotor aircraft. You'd think that someone would have developed a workable, certifiable example in the nearly seventy years that have passed. But no... 609 is "close"...but it's been "next-year close" for as long as i can remember. Hey, maybe 2026 will be the year Leonardo gets the 609 certified! Hmm. I doubt it. If I were a betting man, I'd wager that there are issues (aerodynamic or otherwise) with high-speed tilt-rotor flight that are simply insurmountable, and Leonardo is reluctant to admit it and throw in the towel. Maybe that whole "tilting-engines-and-rotors" thing is just a bad idea?
The 609 incident a decade ago was a result of AW modifying the vertical stabilizer and reducing its effective area (for reasons yet publicly unknown aside from maybe mere aesthetics
), which essentially reduced overall yaw authority. Seems immensely risky on an aircraft that
already has no conventional rudder and
relies on differential collective power for yaw control. Add into this the
lack of lateral flapping cyclic on the rotors, and you get a recipe for disaster during high speed dive testing. All of these elements are a departure from the previous half century (and entire history since) of tiltrotor design, test, and flight - so using the 609 with its atrocious control design as good benchmark for a certifiable civil tiltrotor is a bit of a stretch. Ever consider that Bell got out of the program for a reason?
P.S. Unbeknownst to most, in July of 2014 a similar AW609 incident occurred in the same aircraft where the right rotor over-flapped in the same high speed dive scenario and the outboard half of all 3 blades were sheared off by the wing. Almost unbelievably the pilots were able to recover the aircraft and perform an emergency landing (goes to show that considerable loss of blades on a tiltrotor isn't necessarily doom).