You magnificent bastard. Now you get to explain how you scammed THAT hop.
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"Quirks" of Past Aircraft
- Thread starter Wingnut172N
- Start date
I've hit it more than once, and actually teach it to my students (well I used to, I'm a staff dork now) during aircraft handling characteristics sorties. It doesn't take a 60 deg turn either, just G to get the blades coned up. Probably doesn't manifest in a 60L given the light weight, a 60G is north of 20k on just about every training sortie. We actually lost a bird and one crew member due to not understanding this.
ETA: We get auto mode failures from time to time, but I've never heard of an actual full down failure. I have had maintenance screw with an alert bird and pull the stab amp breakers; made the scramble launch very odd as the nose kept trying to point at the ground.
We had a handling characteristics hop in the 60F/H, but mine was 6 years ago. I remember seeing the low-g goofiness, but not the coning roll. Guess I'll transfer my surprise to the fact we didn't discuss it at TPS.
Might it not be evident since the schoolhouse birds are so light?
I actually had to get a TPS guy to help me out with it. I knew about the mixing unit contribution, and I knew there was an aero portion that had something to do with dis-symmetry of lift. When I actually saw his white board drawings I felt like an idiot. When you cone the disc, the front blades see a reduction in induced flow, while the aft blades see an increase. When you draw the vectors for air flow around a blade element it's obvious: increased effective blade AOA in front, reduction in back.
sevenhelmet, I think you're probably right. I don't imagine you'd see much coning at all with a light bird and a 45deg limit. I know when I see it happen I'm kissing the onset of bladestall, usually in a helo v helo fight.
Synix, I suppose it's possible. What is effectively "rotating weight" I suspect plays a roll in how much a given system will cone, but we're rapidly getting beyond the basic phase lag understanding of rotor dynamics that your typical pilot is taught, including me!
I suspect it has more to do with typical gross weights and operational limitations. I never ran into the issue without intentionally inducing it until I started teaching at the weapons school. The first time I saw it over and over was fighting air to air without limiting ourselves to a lower Ps line. Think arriving at the merge at around 120knots with a 20k pound aircraft, rolling to to the right and pulling 100% Q, and pulling till you hit the onset of bladestall in an attempt to trade all that speed for turn rate.
All that said, I've seen the same issue pop up at 80 ish knots when trying to retrograde back the way I came after realizing I'd expose myself to a fighter threat. (playing red-air, in a failed attempt to beat the AIM-9X) Once again, seen at Nellis....
I suspect it has more to do with typical gross weights and operational limitations. I never ran into the issue without intentionally inducing it until I started teaching at the weapons school. The first time I saw it over and over was fighting air to air without limiting ourselves to a lower Ps line. Think arriving at the merge at around 120knots with a 20k pound aircraft, rolling to to the right and pulling 100% Q, and pulling till you hit the onset of bladestall in an attempt to trade all that speed for turn rate.
All that said, I've seen the same issue pop up at 80 ish knots when trying to retrograde back the way I came after realizing I'd expose myself to a fighter threat. (playing red-air, in a failed attempt to beat the AIM-9X) Once again, seen at Nellis....
I flew with the Army Aviation Heritage Foundation and had a high school friend who's dad bought one. They are somewhat cheap to buy and very expensive to fly/maintain. Flying around with door gunners and dudes dressed in Vietnam era garb is a sweet gig. They don't like to side flare... I went VT's and still find ways to get my helo on from time to time.
Exactly. Wasn't thinking of that in my first reply.
Those teaching the MTP course at Ft. Rucker are of the same opinion. I never saw a cyclic-mounted-stabilator-slew-up-switch (actual term) in the SH-60B, SH-60F or HH-60H I flew in the Navy. I remember thinking how stupid it was when I saw it for the first time in a UH-60A going through the AQC.
One of the explanations I heard for the crash was that the beeping tone was similar to the engine out tone for the Huey and that initial reactions to the tone in the UH-60A was to lower collective and accelerate (engine failure) vice freezing the collective and aft cyclic. Don't know if that is true. I have never flown a Huey. One verified issue with the stabilator for the early UH-60A was a lack of adequate shielding for the wiring. An anecdote supporting this issue was seeing a stabilator drive full down by itself on a Seahawk aboard CG-51 when the shielded wire was bypassed for troubleshooting.
FWIW, the M model Blackhawk has several improvements for manueverability at high gross weight and/or density altitude. The blades are wider, 24.25" vs 21.75" along the chord. The blades have a 20 degree anhedral droop. The left lateral roller limiter and left bellcrank in the mixing unit have been changed to provide more left lateral control with the wide chord blades. There is also a larger cutout in the scissors assembly for additional movement.
Edit: Also the tail cone stringers and skin are beefed up.
Heard the same thing back in the 80s when I went through the FRS. Component lifetime, etc…
The Army has no pitch bias actuators (PBA), so we don’t get the “feel” thing at high AOB.
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The Army's Fundamentals of Flight (FM 3-04.203) explains this within its discussion of translational lift. I find that to be a bit paradoxical since the Army seems to dumb everything down. The only other major challenge to the "dumbness" of Army aviation compared to Navy aviation is the "lifties" explanation I heard in navy flight school.
Your software is different, so I'm wondering if you have this...
On the R/S, the "old" hoist up/down switch is now a Mission Display toggle and ACK for the WCA page. It also silences the STAB warning tone. Full circle, I guess. Do you guys have that on the M?
We can silence the stab warning tone via the Master Warning panel or the cyclic mounted VOX-Caut swtich. The VOX-Caut switch also acknowledges caution advisories. As a bonus, it appears to do so quicker than the Master Warning panel. The VOX-Caut switch is right of the trim release and can't be activated without moving your hand from the normal flight position