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  • #31
    Poking around a bit, I sure find nothing on the other craft. There's this from All Hands May '49, which one of the two built unknown. I'd say the guy in the right seat is laughing, or is that screaming in terror, it's hard to tell:
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    We have a tip-propelled machine at our local helicopter museum, called a '53 Hiller H-32 (no "X" in front of that "H" now) the no-tail-rotor deal evident:



    The same shop has a '57 tandem-rotor H-21 "flying banana", I rode in a couple times when first made operable (I'm less brave, then suffer from questionable judgement). Then they booted all the passengers and hangers-on out to practice that auto-rotate thing (landing without power). Down, forward, down, down, forward, down, pull-back...BLAMMO, struck the tail on the tarmac. Whoops. Didn't hurt it too bad, but scary stuff - you only get one chance. We were discussing a portable crate to haul a spare engine around in, the plan being that if they ever had to emergency-land on a freeway or something, a spare engine would be ready to truck to the location if needed. I don't know what they wound up doing, unfortunately all effort toward their projects have to be volunteer, and I couldn't afford to do it at the time.

    Originally posted by Aircooled View Post
    On a related note, my Grandpa told me the story behind the very odd looking landing skids on the XV-1.
    What was that story? Looks like they were made to accommodate landing while moving forward, nose down?
    ...

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    • #32
      I'm frequently asked if I want to come play at our local heritage Museum... and they have an AH-1 Cobra.. I just don't have an interest in it. I've been qualified in every version and taught here at the school house for several years but honestly I'm not sure I trust the maintenance. It's a bunch of dedicated guys... but... ( you only get one chance to be wrong about this stuff )

      That guy in the left seat is yelling something about his leg being wet... ( that's my guess )

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      • #33
        Keith, you're one of the folks in the world I admire sure enough. I'll say it, whether you like me saying it like it or not. Yessir, you're alright, all that you've done.

        You'll even pay attention to the smaller things when you've got a moment to do so, that's not what all folks do.

        Click image for larger version

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        Charter member of the Turd Nuggets

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        • #34
          Originally posted by Loren View Post

          We have a tip-propelled machine at our local helicopter museum, called a '53 Hiller H-32 (no "X" in front of that "H" now) the no-tail-rotor deal evident:
          "On a related note, my Grandpa told me the story behind the very odd looking landing skids on the XV-1."
          What was that story? Looks like they were made to accommodate landing while moving forward, nose down?
          Looking at pictures, McDonnell went through 3 landing skid designs on the two XV-1 aircraft. Original design for the first first XV-1 (53-4016), modified design for the second (53-4017) and a final, extra long design that was retrofitted to both aircraft.

          Aircraft 4016 with original landing skid design:
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          Aircraft 4017 with second landing skid design:
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          One of the XV-1's after retrofit with the final landing skid design:
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          So, the question is "why so many landing skid designs?"

          First some background on the rotor system of the XV-1. Although the XV-1 rotor is tip-propelled like that of the XH-20 and H-32, it differs by using pressure jets instead of the ram jets used on the others. In a pressure jet, combustion air is provided by an engine driven air compressor. The compressed air is routed through the hollow rotor hub and hollow blades. At the blade tip is a combustion chamber where fuel is mixed in and ignited.

          The flight profile of the XV-1 was to take off in vertical flight using the pressure jet driven rotor and accelerate forward in helicopter mode to minimum autogyro speed. At this point, the tip jets are shut off and engine power is transferred from the air compressors to the pusher propeller. The propeller is then used to accelerate up to cruise speed. To land, the process is "simply reversed". In reality, however, re-igniting the pressure jets while in autogyro mode proved to be very difficult. I remember my Grandpa giving a statistic of "1 in 3". I don't remember if that was the odds of success or failure in firing up the pressure jets, but either way, those numbers resulted in a lot of autorotation landings. Early on in the flight test program, a hard autorotaion landing on the original design landing skid resulted in the the aircraft nosing over and crushing its nose structure. The pilot's foot was also injured, putting him out of action for a while. My Grandpa (a control systems engineer) was called in to make a small design change to the rudder pedals to minimize the potential for future injury to the pilots. In addition, the airframe structural engineers were called in to redesign the landing skids. I suspect they were told that, given the large number of autorotation landings the XV-1 test program was facing, they better get busy designing a landing skid that can both take the abuse and prevent the aircraft from nosing over. As you can see in the previous picture, this resulted in one very robust looking skid design.






          Attached Files

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          • #35
            I love stuff like this!

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            • #36
              Bob if you love this junk... here's a couple of tid bits for you. Those stub wings create lift in forward flight which reduces the requirement for the main rotor to create lift... All single rotor helicopters have an issue called "Dissymmetry of lift" .... air flow is added in forward flight to the advancing blade.. ( the as it rotates from the tail to the nose ) and subtracted from the retreating blade ( spinning from nose to tail ) normally we reduce the mechanical angle of the blade on the advancing side and increase the pitch on the retreating side... to have equal lift across the rotor system... ( to turn we increase or decrease lift on one side or the other )... At some point ... normally around 212kts the airflow on the advancing side becomes so great we can no longer compensate for it and the aircraft will have what's called Retreating blade stall.... So this crap is our speed limiter... that's why Helicopters can only go ... x so fast.... after that you have to start adding crutches like these "Stub Wings and pusher props"... they do increase that speed limit by quite a bit.

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              • #37
                Thanks for your valuable input on this topic ... very nice hearing from you !

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                • #38
                  Originally posted by Aircooled View Post
                  Aircraft 4016 with original landing skid design:
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                  Originally posted by Aircooled View Post
                  Aircraft 4017 with second landing skid design:
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                  ...

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                  • #39
                    Originally posted by Loren View Post
                    Ha, ha, ha, ha !!!

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                    • #40
                      Keith, thanks for the lesson.. Always wondered how it could lift and go.. Always knew I was missing "something"

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                      • #41
                        Cool brainy stuff!
                        Love history
                        Last edited by corvettedad; June 3, 2016, 09:19 AM.
                        Pt 2010, Long Haul 2011,12,13,14,15,16,17, 18, 19, 23
                        If you wait, all that happens is that you get older

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                        • #42
                          Very ironic how I hated History as taught in school, but since watching the History Channel episodes and Discovery Channel documentaries, I'm fascinated !

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                          • #43
                            Originally posted by Monster View Post
                            Very ironic how I hated History as taught in school, but since watching the History Channel episodes and Discovery Channel documentaries, I'm fascinated !
                            So so true, me too. The Military Channel (AHC).....World War II in color. The Greatest Generation of American men. Enthralling. Unit asked me one time, "Are you watching Hitler AGAIN?"

                            I've had the "opportunity" to work with Germans on three capital projects. One guy from South Carolina was standing there beside me in Michigan when he said, "Leave it up to the Germans to start two world wars and lose them both." HAHAHAHAH!
                            Last edited by pdub; June 3, 2016, 06:54 PM.
                            Charter member of the Turd Nuggets

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                            • #44
                              Originally posted by peewee View Post

                              So so true, me too. The Military Channel (AHC).....World War II in color. The Greatest Generation of American men. Enthralling. Unit asked me one time, "Are you watching Hitler AGAIN?"

                              I've had the "opportunity" to work with Germans on three capital projects. One guy from South Carolina was standing there beside me in Michigan when he said, "Leave it up to the Germans to start two world wars and lose them both." HAHAHAHAH!
                              For it was OH NO NOT MIDWAY AGAIN!!!
                              Correct, an era of patriotic tough individuals that did what had to be done! Hat's off!!
                              Pt 2010, Long Haul 2011,12,13,14,15,16,17, 18, 19, 23
                              If you wait, all that happens is that you get older

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                              • #45
                                PBS had a series on "Nazi Megs Weapons (or Machines)"
                                Did you know they had a battleship huge tank? So big it could not help much but boy it sure had firepower..
                                The segment on their submarine base in france was awesome.
                                As was the D-Day beaching..
                                Yep, we beat the Nazis just as they figured out unmanned bombs from land to land, jet fighter planes..
                                Beat the jets because they were so fast the pilots were shooting too late to hit their targets..
                                We done it with guts, determination and the greatest generation!
                                Love history, always did..

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