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Bearhawk wins New Zealand STOL Championship

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  • #16
    How about a rocket assisted drag chute that blows out the tail cone on touchdown :-) That should reduce ground roll !

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    • #17
      Originally posted by BAnton View Post
      Do you have a good comparison of performance with & without the VGs?
      Yes I have posted some thread(s) about that. A search should turn them up: https://bearhawkforums.com/forum/fly...sing-vgs/

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      • #18
        Originally posted by whee View Post
        Great pics! Really impressive. I hope there is a video coming.

        Any thoughts on what could be done to further increase performance? Would be nice to cut that landing roll down some.

        Also, It looks warm there and I need some BH specific STOL training...
        Come on over Jon - bring the family!

        I agree about the landing roll - it's the weakest point. Although I did beat the Maule by a few metres I think.

        To improve further:
        - Fly slower, first and foremost. Short landing means minimum kinetic energy, KE = 0.5mv2. So velocity is most important. Ideally, fly slower in an easily controllable state - slats and extreme AoA are not useful. Flaps is where I need to focus next, lots of room to improve there. I have a few irons in the fire there. Maybe flaperons additionally, although weighty and invasive to modify....
        - The plane needs to be lighter (which I am working on).
        - Right now I am putting some super heavy stuff in the baggage tube right at the L/E of the horizontal stabiliser. I need to find a way of keeping some weight in the tail, while saving weight overall. If the CG is too far forward then I cannot brake at 100% force, because I can't keep the tail down.
        - Maybe softer tire pressure. I land want to land with a high descent rate. That way the ground and landing gear soaks up kinetic energy, which is energy the brakes don't have to deal with.
        Last edited by Battson; 02-11-2019, 06:53 PM.

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        • #19
          I wonder about the difference with “dumping” flap on touchdown. My understanding (with little TD experience) is that this is done to reduce lift on a taildragger immediately upon touchdown.
          But this coincides with the fastest part of the ground roll, where aerodynamic braking is most effective (V squared is at its highest). I guess it may be a trade off between weight on wheels for wheel braking vs max aerodynamic drag.

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          • #20
            Killing the lift increases weight on wheels, which makes increase braking friction. Newer transport category aircraft all have auto extending speed brakes/spoilers that extend on touchdown (or a parameter or two).They don't move the flaps because the actuators are too slow. The boards pop up really quick.

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            • Nev
              Nev commented
              Editing a comment
              So quick in fact they can sometimes ruin what would otherwise the smoothest of touchdowns

          • #21
            Originally posted by svyolo View Post
            Jonathon;
            I don't know your experience before your BH. But you have shared your experience with your BH. In the last few years you have gone to bigger and bigger tires, and rougher LZ's. Bigger and lower pressure tires introduce another natural frequeny to the suspension tuning. How does the standard suspension, from a kit, handle it? Do you wish for more damping, or less?
            Big tires make the suspension's job easier. The system is over-damped, so natural frequency isn't relevant. Damping is perfect regardless of tire size.

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            • #22
              Trying not to pull this convo too far into the weeds, here's a great example how dumping flaps on the Maule helps to land short. I chose this particular video because the surrounding buildings and other things give it a good visual reference to see how it can assist when landing short. And because I'm currently flying a Maule in prep for Bearhawks-ville. Note that later Maules have a closed-loop flap system that allows them to go to -7 degrees on the flaps, where the Bearhawk doesn't. But I'm betting that flaps-zero on a Bearhawk is a pretty amazing thing, too.

              Last edited by Chris In Milwaukee; 02-11-2019, 09:50 PM.
              ​Christopher Owens, EAA #808438
              Project "Expedition"
              Bearhawk 4-Place Scratch Built, Plans #991
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              Germantown, Wisconsin, USA

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              • #23
                Originally posted by Nev View Post
                I wonder about the difference with “dumping” flap on touchdown. My understanding (with little TD experience) is that this is done to reduce lift on a taildragger immediately upon touchdown.
                But this coincides with the fastest part of the ground roll, where aerodynamic braking is most effective (V squared is at its highest). I guess it may be a trade off between weight on wheels for wheel braking vs max aerodynamic drag.
                Dumping the flaps is done to increase weight on the mains, and increase weight on the tail. On the Bearhawk especially, flaps down means a lighter tail.

                Imagine how long it would take to roll to a stop, with just flaps down for drag (say the plane was on ice for argument's sake). Air resistance doesn't compare to braking power. Going from 30-something knots to 0 in less than 50m requires maximum braking from the moment the wheels touch, and this is only possible with flaps retracted.

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                • Nev
                  Nev commented
                  Editing a comment
                  That makes sense Jon, thanks. It’s a new world to me, and nice to learn.

              • #24
                Originally posted by svyolo View Post
                Killing the lift increases weight on wheels, which makes increase braking friction. Newer transport category aircraft all have auto extending speed brakes/spoilers that extend on touchdown (or a parameter or two).They don't move the flaps because the actuators are too slow. The boards pop up really quick.
                The slats auto retract as well.

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                • #25
                  Jon,
                  I see you are listed in the "Heavy Touring" class. Is there any requirement to carry a certain amount of weight in that, or any other class? It would be interesting to see how different aircraft in the same class could do in "real world" configuration. Either a certain load (250kg) plus pilot and whatever fuel you want, or a certain load including the weight of the pilot and fuel.

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                  • #26
                    Originally posted by svyolo View Post
                    Jon,
                    I see you are listed in the "Heavy Touring" class. Is there any requirement to carry a certain amount of weight in that, or any other class? It would be interesting to see how different aircraft in the same class could do in "real world" configuration. Either a certain load (250kg) plus pilot and whatever fuel you want, or a certain load including the weight of the pilot and fuel.
                    If I'm incredibly industrious this winter and spring there's a tiny chance I'll be able to compete in the talkeetna stol comp again this year(with the bearhawk instead of the highlander) which is everyone at mgtow -3% allowable, and there is a weigh in.
                    Of all the stol comps we have every year it's the only one I go to because it's the only one that represents how Bush airplanes are flown in the wild.
                    I dont think a bearhawk can win though because there's a couple sq12s that usually show up and they'd be in the same weight class. Slats and horsepower always win competitions.
                    But still it's what I usually base my performance off plus some margin of error.... or a lot of margin depending.

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                    • #27
                      Originally posted by svyolo View Post
                      Jon,
                      I see you are listed in the "Heavy Touring" class. Is there any requirement to carry a certain amount of weight in that, or any other class? It would be interesting to see how different aircraft in the same class could do in "real world" configuration. Either a certain load (250kg) plus pilot and whatever fuel you want, or a certain load including the weight of the pilot and fuel.
                      Quite the opposite! Our contest is based on Valdez and some people go to lengths to keep weight down.
                      The NZ event aims to be a safe spectator sport which demonstrates the maximum performance of the aircraft, and an interests the crowd.
                      Empty planes are better for the crowd to watch in my opinion.

                      As a result, the planes at the lighter end of the bracket (like Maule / Bearhawk / 180) have an edge, but it depends who competes and how well they fly their machine. The Helio Courier would be hard to beat despite the 4,500lb gross.

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                      • Mark Goldberg
                        Mark Goldberg commented
                        Editing a comment
                        There has been a Helio Courier the last couple years at the Texas STOL Roundup. I suspect the pilot is not an ace in that plane because his numbers are not real impressive. Nothing close to what you did Jonathan. MG

                    • #28
                      Congrats on the win Jon!
                      https://generalaviationnews.com/2019...=TPOA-20190214

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