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MV-22 and "HOT LZ's"

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  • MV-22 and "HOT LZ's"

    Does the Marine Corps plan on taking the MV-22 into hot LZ's to do medivacs, emergency ammo resupply etc like the 46's in RVN?

    I was an eyewitness to what the 46's went through. I'm having great difficulty attempting to visualize a MV-22 attempting a high speed approach and departure being accompanied by a fusillade of small arms fire, RPG's, and the off .50 Cal thrown into the mix.

    In my memory, I recollect that 53's were absolutely barred from going anywhere near a hot zone in RVN.

    I'll save judgement until I see a MV-22 go into a hot zone at 40 knots, touch down and depart in seconds.

    I don't suppose they have "hover aft" do they?

  • #2
    Hover Aft, Hell they can't auto. 53's did go into hot LZ's at least in 72 they did. I also have concerns abut that acft and rotor wash in LZ's, all the trash its throws up? Can we put more than 1 in at a time
    top A

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    • #3
      Has the defensive weapons issue been resolved? Back in the mid-80's when I was the MAG 26 Ordnance NCOIC and the operational study was sent around for chop, the answer to my question about "where are the guns" was that problem will be addressed later. Last I heard there still wasn't a fix.

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      • #4
        I'll save judgement until I see a MV-22 go into a hot zone at 40 knots, touch down and depart in seconds.

        I don't suppose they have "hover aft" do they?
        Not familiar w/"hover aft" but proprotors can be rotated 7.5 degrees aft of vertical to aid w/deceleration. My impression is that they can decelerate and accelerate much quicker than a helo. Given proproter/nacelle movement of 8 deg/second, they can be at 200 plus knots in around 20 seconds.

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        • #5
          "Hover Aft"

          [FONT=Verdana][SIZE=3]Top A

          Please explain to those that are not familiar with "Hover Aft" is so that those that are new to the board or not familiar with the H-46 and what it had to do in RVN at Pinnacle LZ's where they were too big for the zone but just enough clearance was available to "Hover Aft".
          [/SIZE][/FONT]

          Brook Stevenson
          9/'67 - 10/'68

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          • #6
            Hover Aft was a way to program the aft head to bite more on approaching and/or landing, it could act like a speed brake for those pilots who knew how it was suppose to work. it was mostly in 'A' models but a few 'D's has it. If we has a small LZ we used the hoist and/or a spire rig or chopped off branches.
            top A

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            • #7
              Hover Aft

              The heads do program back but it also gives a better field of view during the flare. As explained to me by a pilot whose hover aft failed, without it you end up with the cyclic back against your spleen. In this situation, should the hover aft then kick in, you have to avoid the oncoming backflip. After repairing said hover aft (failed 40 knot relay), the pilot agreed to test hop the plane once I agreed to ride along. The test was done at 5,000 feet just east of MMAF.

              Wayne Stafford
              HMM-265 69-rotate-69/70

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              • #8
                Hover aft

                Hover aft was a system that caused the rotor heads to rotate rearwards. Its purpose was to change the attitude of the aircraft into a nose down attitude. Without it, the aircraft would have ended up very nose high late in the approach and would have needed full forward stick. It was engaged manually by a switch on the center console (I think) and was not supposed to be engaged above 70 knots.

                But it was quickly discoved that it was a fabulous speed brake, engaging it at cruise speed caused a very rapid decrease in speed and combined with a 'buttonhook' enabled a very rapid approuch. However it didn't do a lot for airframe life. Telling pilots not to engage it above 70 knots didn't have much effect, "If I need it, I'll use it" was the most common answer I heard. Eventually an interlock was installed to ensure that the system could not be engaged above 70 knots. But there's a way to cheat that too.
                John

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                • #9
                  Hover Aft

                  John Dulligan said:
                  Eventually an interlock was installed to ensure that the system could not be engaged above 70 knots. But there's a way to cheat that too.
                  Since John is the resident CH-46 guru and my hero in that regard, I'll certainly bow to his expertise......Having said that, it must've been a "D" model mod and thereafter, 'cause we sure did it to a "faretheewell" with our "Alphas". Never worried as much about getting hit going into a "Hot" LZ, since we could be VERY fast and quick in that regard, but going out with any "big" load could be an issue. Never did figure how to make "hover Aft" help us there! LOL!
                  Semper Fidelis
                  Joe


                  Phu Bai tower:
                  YW-11 for Phu Bai DASC-
                  Remember, These are "A" models!
                  YW-11 BuNo-151939
                  '65 Model CH-46A

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                  • #10
                    Hover Aft

                    I think the mod was in 1969 and it definately was first in the 'D', so there were plenty of birds around without the interlock. When I got back to 'the world' in late '69, (I arrived Christmas Eve to temps of 10 degrees and snow, quite a shock to the kid still dressed in tropical uniform), I had some conversation with the guys in Engineering who were horrified to hear that pilots were still using Hover Aft above 70 knots even though there was a note in the Natops Manual not to do it. They clearly didn't understand combat pilots whose timeframe, if they were being shot at, was the next 60 seconds. I'll do whatever I need to do to get through that alive. I'll worry about anything else later, if there is a later. If using Hover Aft above 70 knots will help and the tail won't come off now, well then I'll use it.

                    Welcome to the big bad world out there beyond Morton, Pa.
                    John

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                    • #11
                      Originally posted by jdullighan View Post
                      Eventually an interlock was installed to ensure that the system could not be engaged above 70 knots. But there's a way to cheat that too.
                      I was introduced to Frogs in 1972 in the "D" model. The interlock for Hover Aft was built into the pitot-static system. The only way that I know to defeat it is to reach out and put your finger over the pitot tube, a not too easy manuver. Are there other ways John? A good pilot could get a Frog in and out of a zone just as well as someone trying to do it by cheating the system. Hopefully once it was determined that using hover aft above 70 knots was detrimental to crew longevity, the practise stopped until the interlock was installed. The attitude of "I'll use it if I have to" probably wouldn't sit well with those that would have to fly the aircraft afterwards.

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                      • #12
                        Buttonhook turn/approaches

                        D Churchin said:
                        A good pilot could get a Frog in and out of a zone just as well as someone trying to do it by cheating the system.
                        DChurchin, have you very much time in "A" models?? If you do then I'll apologize in advance for the below info/opinion. I rarely substitute my knowledge for that of an experienced pilot. However, I was in "A" models in RVN for my entire tour during 1967-68 in HMM-165 and "F" models CH-46's in 1969-70 in HMM-163 with significant flight time as Crew Chief/Crewmember and in the left seat on test hops and other, with more than the usual amount of "stick time" in both squadrons because I loved to "drive" and wasn't too bad for a snuffy...I have NEVER seen or heard about anyone getting in an LZ as fast as an Alpha or very early Delta model with the manual hover aft feature used to "horse around" the bird in a very short time frame. They were exceptionally quick landings and most were relatively smooth. Although the automatic feature was nice and helped keep hands free for radios/maps, etc. they were never as quick as a "hover aft buttonhook"! The bad thing about losing airspeed and turns at the same time was making sure it happened when you were VERY near the ground or you got embarrassed (or worse) when the bird fell the rest of the way to the ground! LOL!
                        Semper Fidelis
                        Joe


                        Phu Bai tower:
                        YW-11 for Phu Bai DASC-
                        Remember, These are "A" models!
                        YW-11 BuNo-151939
                        '65 Model CH-46A

                        Comment


                        • #13
                          Hover Aft

                          Correct me if I'm wrong, but didn't the folks at Boeing/Vertol suggest that the station 410 failures were in some way attributed to the high speed hover aft approaches - I hope the MV pilots have easy access to the pitot tube.

                          Comment


                          • #14
                            Station 410 failures

                            Tom,
                            I heard several root fauilure causes for the aft pylon failures (station 410) including "hover aft" high speed approaches. Walt Jones was in charge of the mod crews on Okinawa for HMM-262 and did some of the very first mods. He could shed more light on this, I'm sure.
                            Semper Fidelis
                            Joe


                            Phu Bai tower:
                            YW-11 for Phu Bai DASC-
                            Remember, These are "A" models!
                            YW-11 BuNo-151939
                            '65 Model CH-46A

                            Comment


                            • #15
                              Hover Aft

                              Joe,

                              Here's a excerpt from your friend John Dullighan's "Cinderella Bird" on Hover Aft

                              A maneuver was strictly forbidden, but the pilots would do it in an emergency until Boeing put in an interlock to stop them. There is a trim feature called 'Hover Aft', which automatically tilts the whole rotor plane aft, depending on airspeed, to keep the fuselage as close to level as possible. Without it aircraft would get very nose high in a quick stop. When first installed, 'Hover Aft' could be engaged manually but was not supposed to be engaged above seventy knots. But some joker found that if it was engaged at the cruise speed of 120 knots, it acted like a speed brake slowing the aircraft down very quickly. Combined with a buttonhook, the result was an extremely rapid approach.

                              It also overstressed the airframe, although it didnít break it. The attitude of the pilots was they would use it if they needed it. The aircraft might disintegrate one day but they would probably be long gone by then whereas they were risking being shot down now. There was much wailing when the latest models arrived with much more power and no pilot ever has enough of that, but no manual 'Hover Aft'.

                              In the summer of 1969, I got an emergency bulletin from Boeing instructing me to brief the pilots not to engage 'Hover Aft' above seventy knots. I briefed an all pilots meeting, with full details of what it did to the airframe. First question was: "Will the tail come off if I do it?".. .."We..ell, no I don't think so, but it overstresses the airframe and it may fail later", was the reply. I already knew what was going to happen. Later in the club I was told "You're a nice guy John, and we know you have to follow the company line, but if I need it, I'll use it. F**k the airframe, it'll probably fail next year and by then I'll be a civilian."

                              When I got back to the factory and I was debriefed by the Engineering group, I was greeted with incredulity when I told them what the pilots said. "You mean to say they'll still do it, even after we've told them not to? Even when we put it in the pilot's manual? Don't they know what that does to the airframe?" They clearly did not understand combat pilots, that when you are being shot at, one's time horizon shortens immensely. The near future is the next twenty seconds and the far distant future is five minutes away. If they didn't want something to happen, then make it impossible. Thatís why the interlock was installed. And thatís why the Navy likes the Marines to fly the same airplanes.

                              After every war, new pilots do not learn the more dangerous techniques that the operational pilots know. There would be too many accidents if they did. To be fair, in peacetime, pilots donít get the chance to fly as much or in the same conditions as pilots do flying combat missions. In Vietnam helicopters routinely flew below fifty feet, an altitude that will have the MPs waiting for you if you do it in peacetime. But Second World War fighter-bomber pilots would have considered 50 feet to be in the stratosphere.

                              Common knowledge disappears fast. Within ten years, the last junior pilots with 'The Knowledge' are now field grade and moving out of flight operations and the new pilots donít know. After 20 years, they donít even know that they donít know.

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