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One more for the acro inclined...

Discussion in 'Aviation Chat' started by Chupacabra, Dec 19, 2009.

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  1. Chupacabra

    Chupacabra F1 Rookie
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    #1 Chupacabra, Dec 19, 2009
    I've been working on perfecting my hammerheads lately. Unfortunately, my training plane is not suited for any less than 1/2 G, but it's my understanding that if you modify the hammerhead a bit, you will never quite get to 0 or negative. What I've been doing is initiating the pullup at around 120 MPH, then smoothly going full rudder with a little opposite aileron as soon as the wings are at the vertical instead of waiting for a particular airspeed (60-55 recommended for negative capable Citabrias). Somehow, I'm still ending up with an indicated -2 G. I've never had an engine problem, but it's still bugging me that I just can't seem to do it without getting under 1/2.

    Any suggestions? More speed, maybe 140, before initiating the pullup?
     
  2. Roger103

    Roger103 Karting

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    #2 Roger103, Dec 20, 2009
    I can't help you with keeping your maneuver in the G force range that you would like. But I would like to ask what kind of aircraft are you using? Most FAA aerobatic aircraft are good up to -3 gs. Even a normal category aircraft can take -1.52gs.
     
  3. Roger103

    Roger103 Karting

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    #3 Roger103, Dec 20, 2009
    Or and you wanting to keep the g force less due to your engine (non inverted oil system)
     
  4. Chupacabra

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    #4 Chupacabra, Dec 20, 2009
    Yes, exactly. This particular 7KCAB doesn't have an inverted system, so I'm (obviously) limited to how much time I can spend upside down and in negative G. It had a prop strike (not my doing!) about a year ago and was supposed to come back with an inverted system after the rebuild, but that never materialized :(
     
  5. Bob Parks

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    #5 Bob Parks, Jan 1, 2010
    All that I remember in doing hammerheads is to feed in enough aileron just before rudder to keep the advancing wing from rolling you to a negative position. I never was taught the method of reading G in all of that but I'm not saying that it wasn't correct. It was just done by feel, I guess, but when you get it right it is a fun maneuver. I personally don't think that high entry speed is as important as coordination at the apex. You are flying an airplane that hangs on to speed a lot longer than an old biplane so you are afforded the luxury of time to blend the input of the controls to do a nicer maneuver,I believe. You are doing good stuff.
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  6. Chupacabra

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    #6 Chupacabra, Jan 1, 2010
    Thanks, Bob; good to hear you think I'm going in a worthwhile direction! It sure is a lot of fun! I guess I'll try cranking a little more aileron in next time...I've been using what I thought was sufficient, but I'll see what happens with close to full deflection, maybe that will take care of it.
     
  7. Tim Wells

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    #7 Tim Wells, Jan 4, 2010
    What kind of plane is it? In a Stearman I always point it downhill to about 140 and pull up for any rolls, loops or whatever but it has a heavier engine (300HP Lycoming with a 2B20 prop).
     
  8. Bob Parks

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    #8 Bob Parks, Jan 4, 2010
    Ah yes! You are flying the best combination for a Stearman, I think. It adds enough HP but not the extra weight of a 450 or 650. I flew one with the entire front end off of an AT-10, cowling , engine, and prop and it was an absolute delight. I don't think that there is an airplane anywhere that can equal the flyabilty and strength of a Stearman. They just seemed to me to be a perfect airplane for training someone to do whatever they wanted to try without any danger. They were 13 G up and down and always displayed a sense of wanting to fly as much as you did AND forgave any clumsiness in your efforts to learn maneuvers. How I loved my days in that airplane! My son and I had a wonderful day in a 450 Stearman some time ago buzzing the shores of the Columbia River, shooting through the gaps in stands of poplar lining the meadows along the bars and scooting over a barge loaded with fir chips that we could smell when we went over. Then we did a wing over at Beacon Rock and headed back down the river and flew low over a nudist beach where some scrambled for their tents and others came out and waved at us as we went by at 100 feet. What a great day!
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  9. Bob Parks

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    #9 Bob Parks, Jan 4, 2010
    The name of that beach is Rooster Rock that isn't a rock at all but a big sand bar. Funny people.
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  10. Chupacabra

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    #10 Chupacabra, Jan 6, 2010
    I'm in a 160 Horse injected Citabria. 140 is standard entry for loops etc. According to the placard, 140 is the target airspeed for hammerheads, too. For whatever reason, when I went up with an instructor to do some tightening up, I went for the dive and he said, "Just go right into it at 120 MPH." So, I tried it, but it feels much better with more speed. It's easier to maintain a straight upline and it seems to keep the Gs from going too far negative.

    I REALLY wish I had access to a Stearman. That looks like a seriously fun aircraft.
     

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