Totally agree. Interesting concept, but the reality is that the technology has never proved reliable enough to sustain continued safe mission capability. It’s only a matter of time before the next mishap, and God-forbid, more fatalities.
Just looking at the picture, you can imagine as the rotors tilt up and down and the weight of that machine, the high torque and tension loads that are constantly being placed on all the various parts. Has to then create rapid wear. My eyeball engineering at work.
Perhaps NDT of all parts made of that material, today’s imaging methods are very good especially the CT Scan version of x-ray, plus there’s traditional eddy current
Because you said so? Good thing there are better engineers than you on the job.
“Look like…” yep, that’s aways the first and best consideration in engineering.
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MH-53E Sea Dragon: The U.S. Navy’s MH-53E Sea Dragon had a class A mishap rate of 5.96 per 100,000 flight hours from 1984 to 2008, which was more than double the Navy’s average of 2.26. This rate refers to serious damage or loss of life.
Mishap rate
The Osprey’s 10-year average mishap rate is 3.43 per 100,000 flight hours, which is in the middle of other aircraft flown by the Marine Corps
Perhaps because Blackhawk losses are primarily due to known factors, some of which are not attributable to the machine itself? Perhaps because the Blackhawk has been in service longer? Perhaps because the Blackhawk losses are more acceptable due to a different mission profile? Perhaps …
Such a blanket “Well, whaddabout …” comparison begs for substantiation.
I originally thought that too, but then after learning more about some of the issues it has had over its lifespan and the details of how it operates, I have come to the conclusion that tiltrotors are just trying to do too many things to be great at any one thing. Similar to the adage “if you try to please everyone, you end up pleasing no one”.
That’s actually how a lot of engineering ideas begin. When the Wright brothers were designing their aircraft, they looked to bird wings for inspiration. It’s no accident that a lot of the early gliders kind of look like birds.
Engineering also involves a lot of observations, and I have observed that exposed open hinge points often do collect a lot of foreign material.
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If they truly had an “abundance of caution” in mind, they would ground them permanently, reuse anything good, and cut them up.
Well, there’s always the Bell V-280 Valor as an alternative.
The only thing wrong with the V-22 is it gets too much media attention. The V-22’s accident rate is no worse than other aircraft and in some comparative cases less as pointed out by astute posters with substantiating facts. Gee a part that’s never broke before…broke, which forced a precautionary landing and it’s time or past time according to some folks to park the aircraft and never use it again given its history of breaking parts, like that’s never happened before.
For what it’s worth, the V-22 has been around for more than 30 years and longer in concept with the Bell XV-15. The downside to its accident rate is the irrefutable fact it can and does take a lot of lives with it when one fully loaded crashes given its troop-carrying capability.
The tilt rotor concept is not the problem. The Marine Corps as its progenitor and primary mission user accepts the operational risk associated with the V-22 for the sake of its unique mission capability same as it does for the latest addition to its inventory of technologically complex VTOL aircraft, the F-35. Risk and complexity of the equipment used are handmaidens that require good engineering to maintain a proper balance.
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I’d hang my wings up before I flew that thing.
I disagree. There are several problems with the tilt rotor concept, and especially as implemented by the V22. 1) All of that rotating, gyroscopic mass causes a great deal of stress on components that a traditional helicopter or prop-driven aircraft does not receive, 2) The V22 cannot takeoff or land like an aircraft due to ground clearance with the prop-rotors, so it has to takeoff/land more like a helicopter, 3) But, it can’t auto-rotate like a helicopter either, so the transmission and driveshaft is a single point of failure, and it absoutely needs at least one engine to be operative, 4) All that mass out on the ends of each wingtip also has a lot of inertia, which doesn’t help with stability, especially if one engine is even momentarily creating more or less power than the other, 5) The disc loading of the prop-rotors is much higher than a same-sized helicopter, so the downwash is much greater and can kick up a lot more debris during takeoff and landing, 6) Also, with the whole engine tilting, that hot exhaust does more damage to the ground than a helicopter would. This means in some cases, a helicopter could get in and out of an area that the V22 cannot safely do.
Now, the tilt-rotor concept is a neat-sounding one on paper, and the V22 is an impressive air vehicle to see flying in person (which I have). But considering all of the complexities of its operation and the forces acting on it during transition flight, you’ll never convince me to get on board one unless it will be remaining on the ground.
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- The V22 cannot takeoff or land like an aircraft due to ground clearance with the prop-rotors, so it has to takeoff/land more like a helicopter,
Search YouTube for “v22 rolling takeoff” for videos of V22s operating in STOL mode (the nacelles operate at an angle).
- But, it can’t auto-rotate like a helicopter either,
It can auto-rotate, but not as well as a helo.
- All that mass out on the ends of each wingtip also has a lot of inertia, which doesn’t help with stability, […]
Stability - a resistance to change - increases as inertia - a resistance to change - also increases.
[…] especially if one engine is even momentarily creating more or less power than the other,
Both engines are linked to each other by an interconnecting driveshaft running through the wings. Both rotors always receive the same power.
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That’s still not aircraft-like, because the nacelles can’t be rotated fully horizontally. Actually, it’s not really helicopter-like either.
Apparently there are some situations where the two rotors don’t receive the same power. If I recall, one of the engines may have been surging, though I don’t recall the specific report or the details. In any case, it’s more than just a simple driveshaft connecting the two engines/rotors, and it especially can’t fail while in helicopter mode.
I should have been more specific that I was referring to dynamic stability, where once that mass starts to roll in one direction, it wants to continue rolling in that direction rather than returning back to wings-level. As you stated, that inertia has a resistance to change, so it will take more effort to roll back to wings level.
Gee, all those Lycomings and Continentals keep having these problems with their cylinders being blown to bits due to materiel failures within them. Plus all those Cessnas and Pipers keep having all of these materiel failures in wing spars and seat rails and such, requiring multiple AD’s and 100s of thousands of dollars across the fleets to remedy.
GA should just get it over with and permanently ground these things.
'Cuz the engine would only run backwards?
Wasn’t the Japan crash due to a failure to land at a nearby airport per SOP when they received indication of an imminent failure in the gear train? They kept on flying towards a base much further away, until the imminent failure materialized and the gear train disintegrated while in flight.
“For inspiration” should be “in desperation.” They were having trouble with inadequate roll control effectiveness in even mildly turbulent air using weight shifting and were nervous that a competitor would make first flight before they did. Then they happened to notice seagulls flexing their wingtips when landing in wind gusts and grasped at the concept, implementing wing warping on their airplane and making first flight. They patented wing warping and charged exorbitant licensing fees from anyone who used the patent, even though they discovered that the technology was ill-suited due to a paradox: the larger the airplane the greater the lift, the stiffer the wing structure, the more difficult to warp it for roll control. And stiff-arming it cracked the structure, tore the fabric and allowed water ingress. Yet their aggressive lawsuits for patent infringement clogged the courts and stifled aviation in the U.S. for years.
Fortunately someone discovered that Matthew Boulton, a British inventor, had patented the concept of the trailing-edge hinged “rudder” in 1868 for roll control of airplanes. So the aileron as we know it today was invented some 35 years before the Wright’s first flight, by a guy who wasn’t even a pilot or terribly interested in airplanes, but due to a clerical error the U.K. patent office failed to find it when the Wrights filed their patent application.