negative g pushover

Discussion in 'Aerobatics' started by david0tey, Apr 4, 2012.

  1. david0tey

    david0tey Line Up and Wait

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    Are negative G pushovers a safe maneuver for a new private pilot to do? I had a passenger ask me to do one the other day and fought with myself about whether or not to do it. I never really went over the technique with my instructor but I have extensively researched the correct way to do it. I also know my limits and would not do it for more than a few seconds. I do fly a 172 gravity feed so the fuel is obviously a concern but I don't think a two second pushover would kill the engine. Just wanted to get your thoughts on the manuever.
     
  2. Henning

    Henning Ejection Handle Pulled

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    Seat belts fastened, loose items in the cabin secured, good to push.
     
  3. denverpilot

    denverpilot Taxi to Parking

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    Don't get wild, you'll be fine.

    Start with a bit of a pull first so you make a parabola and don't end up with the nose way below the horizon and the airspeed headed for the yellow.

    Be smooth. No jerking.

    And yes. Everything. Everything. Secured. You especially. Heavy things floating eventually come down and can hit you. People bouncing off things is especially bad.

    Start small. You'll probably be uncomfortable long before any serious high G loads either direction.

    After a little practice you can put a little paper airplane on the dash and "fly" it to the back seat.

    I got over it long ago. Enough flights in moderate turbulence and the whole "floating above the seat" kinda loses its charm. ;)

    I did a super mild push the other day as a joke while my wife was giving me the evil eye about something I said on the way back from Scottsbluff. Just 'cause it makes her smile.
     
  4. david0tey

    david0tey Line Up and Wait

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    Awesome, thanks. Is it better to pull carb heat on and power off before pushing the nose over or should I keep the power in ?
     
  5. N801BH

    N801BH Touchdown! Greaser!

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    Don't be surprised if the engine hiccups.. On any negative G action the carb will lose proper flow through it.. Also since it is a wet sump oiling system any negative G stuff will unport the pick up tube so my suggestion is to keep the push over to a minimum so you don't suck air and hurt the bearings.... Keep on eye on the oil pressure gauge, if it quivers at all stop all negative G stuff... IMHO.
     
  6. Henning

    Henning Ejection Handle Pulled

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    Turn the power off by pushing...;)
     
  7. david0tey

    david0tey Line Up and Wait

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    Nobody listen to this guy! :eek:
     
  8. Henning

    Henning Ejection Handle Pulled

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    LOL, by the time you get down to about half a G you'll start losing power, by zero the engine will be dead. You see, a carb requires gravity to keep the fuel where it needs to be and work.
     
  9. denverpilot

    denverpilot Taxi to Parking

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    You're going to get all sorts of confused by this thread.

    Why not just grab a local CFI and explain that you've seen all those goofy YouTube videos of negative G pushes and that you'd like to experience a mild safe one in a real airplane. You know there are some risks involved and you don't want to accidentally do anything dumb or dangerous.

    Bonus: Find the CFI who'll do spin training and unusual attitudes. If they recommend the use of something aerobatic-rated, fine... but still have them show you mild maneuvering in the Skyhawk.

    Also, even though you're not going for the rating, any CFI can demonstrate the maneuvers required of the Commercial rating, for example, which are good aircraft control maneuvers and very benign. They won't feel benign if all you've ever done is pattern work. They will however open your eyes to the three-dimensions we operate in. Look at the books and the descriptions. Download a copy of the Commercial PTS and envision in a chair how the controls would have to move to do those maneuvers.

    After you've seen and felt it, it's a lot easier to understand.

    Airplanes only fly square patterns because we make them. Climbing and descending circles in the sky are fun. Vertical arcs while coordinating throttle and elevator inputs to hold one airspeed are good practice. So called "Dutch rolls" where the heading of the aircraft stays constant in one direction but you rock the wings from side to side while using coordinated rudder inputs to stay pointed straight ahead are also easy and a hoot.

    A Skyhawk isn't suited for the "tumbling mirth" of the famous aviation poem, but it doesn't have to be a "straight and level all the time" airplane either.

    Have a CFI with grey hair show you how to play safely if the ones with brown hair won't. ;)

    Remember above all the point of learning aircraft control feel is so you can use those motor skills to get yourself out of trouble and also so you can give most of your passengers a smooth comfortable ride. If one asks for the more aggressive maneuvers, a simple steep turn may fit ther desire for "pulling Gs" just fine.

    And check on their condition often, or you'll be scrubbing up the barf out of the carpet.
     
  10. pigpenracing

    pigpenracing Cleared for Takeoff

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    Roll it inverted, then push it all the way around. Lol!
     
  11. Dan Thomas

    Dan Thomas En-Route

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    I've done this in a 172. It's not a negative G maneuver. If a pen or whatever small item set on top of the panel lifts off an inch or two, you have zero G, not negative G. Even one negative G is a serious pull on the seat belt, same as hanging upside down.

    And the engine will continue to run during this. The trick is to start a gentle climb first, then push just hard enough to lift that pen off the panel and stop once the airplane is heading down.

    Dan
     
  12. Henning

    Henning Ejection Handle Pulled

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    BTW, If you do push hard enough to shut the engine down it's not a worry, it comes right back online as you go positive again. It's not a biggie. Aerobatics are taught in planes with carbs as well, engine is always cutting out and in, no worries.
     
  13. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Final Approach

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    The wings will fall off and you will crash into a school for crippled children and your insurance won't pay.

    But other than that, it's really no big deal. Pull, Push, Pull. Don't pull or push too hard. Don't do it if you are significantly over gross.
     
  14. PBristolJr

    PBristolJr Line Up and Wait

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    Pitch the nose up 20* and push a little until you feel light in the buttox. Then go back to straight and level and try it again.. push a little harder each time until your passenger begins throwing up...then push EXTRA hard. ;)
     
  15. Skylane81E

    Skylane81E Final Approach

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    Do keep an eye on the oil pressure, takes very little to drop it to nil in my bird.
     
  16. poadeleted20

    poadeleted20 Deleted

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    Vacuum all the carpeting, too -- hard to fly when all the grit floats up and gets in your eyes. You might also want to do a very careful inspection of the entire airplane (not just the cockpit) for any loose bits which might float up and get caught in flight control pulleys and the like. You'd be amazed how many old washers, bits of wire, etc, you'll find.

    All in all, it's not something anyone will advise you to do in a nonaerobatic airplane, but it is possible to do without compromising safety.
     
  17. whifferdill

    whifferdill Line Up and Wait

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    Just don't try it in a MiG 28 - we all know they won't do a negative G pushover. :D
     
  18. Skylane81E

    Skylane81E Final Approach

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    Bull, I followed one into one, in my skylane no less!
     
  19. denverpilot

    denverpilot Taxi to Parking

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    Only if you don't file a flight plan. ;)

    Over? ;)
     
  20. Old Geek

    Old Geek Pattern Altitude

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    I've heard that gyrocopters also get downright unhappy.
     
  21. bbchien

    bbchien Final Approach

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    R22s, too.
     
  22. N801BH

    N801BH Touchdown! Greaser!

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    I think Nate is correct..... A light plane will break faster then a heavy one..
     
  23. denverpilot

    denverpilot Taxi to Parking

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    I was doubly confused. Both for your reason and wondering who here regularly flies *over* gross.

    It seemed a strange reply more for the latter reason than the former.

    Since this is a Skyhawk, it's probably advisable to only load it to the Utility Category W&B limits, not the Normal category limits if unusual attitudes are being done in it, assuming its an old one with those numbers published for it. And of course Utility Category only if you're going to go spin one.

    I always forget that Cessna dumped the Utility Category on the newer ones, didn't they? Sad.
     
  24. Doggtyred

    Doggtyred Pattern Altitude

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    Negative G's tend to cause airsickness more than positive G's. I recommend bananas for your meal before the flight.

    They dont keep you from getting sick, but dont taste so bad when they come back up.
     
  25. RotorAndWing

    RotorAndWing Final Approach

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    Negative G's in most rotorcraft are bad, really, really bad.
     
  26. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Final Approach

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    Over gross is not a good thing. Playng games while over gross is a really not good thing. It was just a reminder.
     
  27. GCA319

    GCA319 Cleared for Takeoff

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    I've always thought spins were the best first step for someone looking to do something other than the same old straight and level they've been doing. Most people who have spun (and didn't scare themselves) become less nervous when practicing stalls.
     
  28. Ken Ibold

    Ken Ibold Final Approach

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    Keep in mind also that the aircraft's posted g limits are structural. When you go negative, lots of things can happen that are not structural failures. As Ron mentioned, washers and bits of wire and lost pencils etc fly around. Glasses and headsets can come off, a poorly fit oil filler cap can unseat, an old worn Cessna seat tracks that hasn't been inspected properly might even give up a seat. OK, that last one is obviously a stretch. But the point is that structural failure isn't the only thing to worry about.
     
  29. TMetzinger

    TMetzinger Final Approach

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    ODG Yes. One of my pilots in the CG was a former Army Warrant from the Huey community. I remember him talking about the "Jesus Nut" one day and I asked him what it was, and he said it was the nut that held on the main rotor system and if it ever let go all you could say is "Jesus!". And then explained that negative G loads were an excellent way to eject the main rotor.

    IIRC, this is the same guy who was given his own case of orange spray paint after scraping the tail-skid under the Fenestron on the HH-65s one too many times - the Chief AD gave him a class on how to repair it and from then on - he broke it, he fixed it. He learned pretty quick from that point on.
     
    Last edited: Apr 7, 2012
  30. denverpilot

    denverpilot Taxi to Parking

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    +1000000 !

    Once you've seen the "big evil scary spin", it ain't such a big deal.
     
  31. Satchmo10th

    Satchmo10th Pre-takeoff checklist

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    From AOPA's HoverPower Blog
    HoverPower Blog
     
  32. N801BH

    N801BH Touchdown! Greaser!

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    I guess my question is..... How the heck does the Red Bull heli fly that aerobatic routine ??:dunno::dunno::dunno:
     
  33. RotorAndWing

    RotorAndWing Final Approach

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    He's using a BO-105 which has a rigid rotor that's been modified. That coupled with a precision pilot makes that routine possible.
     
  34. N801BH

    N801BH Touchdown! Greaser!

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    Thanks r&w... The word "modified" spelled the difference...
     
  35. bbchien

    bbchien Final Approach

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    ...plus, if you look carefully, his routine is sort of the rotary equivalent of Bob Hoover's- not much negative (if ever) and not more than about 2g +.
     
  36. And R44's. And Jet Rangers. And UH-1's ... :)

    It's the "I was a fixed wing pilot first" recoveries that turn these into accidents. Satchmo's quote is spot on.
     
    Last edited by a moderator: Apr 11, 2012