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Bearhawk cruise attitude

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  • Bearhawk cruise attitude

    In reading about the Bearhawk flight characteristics I've noticed a few (including Budd Davisson) mentioning that as speed approached 140 knots the plane assumes a more nose down attitude and that the flight characteristics aren't as comfortable. I don't think there are many "B" models flying, but has the Riblett airfoil, along with aero profiled empennage, changed this characteristic? Do the Patrols exhibit this flight behavior?
    Thanks!

  • #2
    I can confirm that at higher than normal speeds, the 4-place does adopt a nose-down attitude and becomes uncomfortable to fly. I assume most aircraft with a lightly loaded wing and asymmetrical aerofoil would do this?

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    • svyolo
      svyolo commented
      Editing a comment
      I flew 90 hours in a T-34C a long time ago. Bonanza aerodynamics with a 2 seat tandem layout. Meant for 220 hp and cruising at 160-180. It had a Turboprop with triple that power. It would easily do 230 Kts, and that wasn't even full throttle. Anything over 200 it was heavy on the controls, twitchy, 5 degrees angle of bank and some yaw to hold a heading or course. Very unpleasant. Nobody flew it that way, and we weren't paying for the gas.

      Too much lift, too much drag, but had the power to overcome that. It did climb pretty nice.

  • #3
    Hmmm this is the first I have heard about this - is there a link to the Budd Davisson article? I read his review of the Bearhawk - I don't remember that - but could have missed it. I would be very interested to hear from anyone with the Bravo Wing - is it any different? Does the patrol have the same behavior? The main reason I'm interested in the Bearhawk is the I can do the backcountry flying I enjoy - but I want to get to the Backcountry as fast as possible - so I want a decent cruise speed. Battson when you say "uncomfortable" to fly - are you talking about the nose down attitude - or in addition to that, such as flight controls, etc?

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    • #4
      Bearhawks, and I guess Maules, equipped with smaller tires and not a lot of drag, have extremely wide speed ranges, especially with the bigger motors. I haven't ever flown one, but I would expect heavy and/or twitchy controls at the very high end, and to be control authority limited at the very low end. Neither were designed to cruise at 75% with an IO-540.

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      • #5
        Originally posted by corefile View Post
        I want a decent cruise speed. Battson when you say "uncomfortable" to fly - are you talking about the nose down attitude - or in addition to that, such as flight controls, etc?
        You will get very decent cruise speed - as good as a Skywagon in fact. However, you won't cruise like an RV-6 and land like a Cub in the same plane, that is just too far apart. The Bearhawk A-model can sustain 140 knots indicated (162 mph) in level flight, however you are at 85% power (220 hp). That is burning about 75 L/hr (over 18 US gal/hr), ouch! It's also uncomfortable to fly.

        Yes the nose is lower, which is a little uncomfortable in the seats - but it has knock-on effects for the aerodynamic surfaces, especially at aft CG locations. This is not a Bearhawk-specific quirk. Most aircraft with an asymmetrical aerofoil will see the same.

        The aerodynamic effects make it uncomfortable to fly:
        The wings can approach zero or even negative angle of attack as the speed increases. This leads to a more sensitive or 'twitchy' ride, you can feel all the bumps in the air. The reason for this is because everything is experiencing more aerodynamic force, which means lift becomes more finely balanced with weight. A slight pitch up results in a large increase in lift, compared to weight. The plane's still stable and returns to level flight, but this effect exaggerates the bumps. This is the most noticeable change.

        It also makes the ailerons stiffer because they are not aerodynamically balanced, the air tries to hold them in position. At the same time, the rudder and elevators (which are aerodynamically balanced) produce more force, so small pedal or stick pitch inputs move the aircraft a little more. But the roll inputs are a touch stiffer. It's not a dramatic change, but if you are paying attention you will notice it. Some people will report the ailerons become really stiff at high speeds i.e. in a dive, this is often because they have not rigged their ailerons correctly - both ailerons are usually too high or too low, which causes them to stiffen up.

        But I need to stress - we are talking about flying an aeroplane in a way it was never designed to be flown, with unsustainable fuel consumption levels, and all these problem affects pretty much all light single engine aircraft.

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        • #6
          I think the designer can choose heavy or sensitive at high speeds. Heavy is almost always the choice, and the correct one. Too sensitive, and you can pretty quickly and easily break the plane. Or yourself.

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          • #7
            Originally posted by Battson View Post
            You will get very decent cruise speed - as good as a Skywagon in fact.
            Which is what I'm flying now, I love my Skywagon... I just don't love maintaining a 57 year old certified aircraft.

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            • #8
              Originally posted by corefile View Post

              Which is what I'm flying now, I love my Skywagon... I just don't love maintaining a 57 year old certified aircraft.
              I’ve disbelieved Battson before and proven myself wrong (it will likely happen again) but I don’t see my BH coming even close to keeping up with the wagon I did my refresher in. I’m talking at same/similar fuel burn numbers. Blackrock flew to AK with a wagon and said he kept up pretty good; the wagon slowed down just a smidge and he pushed up his speed a bit; fuel burns were the same it I recall correctly.

              The BH is significantly more fun to fly, mine has equivalent or better useful load, better access because of the baggage door, better/easier/cheaper to maintain, and reasonably close in performance. Would I trade a wagon for one, I’m not sure. Probably depends on how my IA is treating me more than anything else. If you want to decide for yourself I’ll meet you in the Idaho backcountry and we’ll do some flying.
              I'm a Tapatalk user so I can't see your "comment"

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