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Thread: Bearhawk Patrol

  1. #1
    Bearhawk Builder's Avatar
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    Bearhawk Patrol

    Thought I'd post a few pics of the latest project. The kit was delivered on January 12th, a seaplane fuselage with left door. We wanted to maintain the left door and still have dual left quadrants so I came up with this arrangement, seems to work very well. One of Bob Barrows' O360's, Whirlwind GA prop. Dynon 10 inch screen, radio, transponder, intercom, knob panel, ADSB. Sport Aircraft Seats, The wings are closed up and ready for paint, still have to cover the flaps and ailerons and finish up the wing tips. I'll update empty weight when done. I don't expect it to be the lightest Patrol but sure is a nice one.
    Click image for larger version. 

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  2. #2
    Chesney's Avatar
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    The plane looks amazing in these photos, and yet somehow looks even better in person


    Sent from my iPhone using SuperCub.Org

  3. #3
    Crash, Jr.'s Avatar
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    Can you tell a little about the throttle quadrant? It looks like it stays with the door but I don't see any way for it to disconnect to allow the door to go down. How does that work?

  4. #4

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    Bearhawk doors open like a car door?
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  5. #5
    Bearhawk Builder's Avatar
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    The doors hinge is at the front of the door. The quadrants stay on the door and swing with it. The rod end bearings have lateral movement in them when 1/4" spacers are place on each side of the bearing ball, this allows the door to be swung open. It does advance the throttle as the door is opened and the belcrank is pulled so the door is placarded "Engine off for left door use". My IA buddy was worried about 'hysteresis' which is the accumulation of small errors resulting in a large deviation however with this arrangement there is zero play or slop in the system. It should work well.Click image for larger version. 

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  6. #6
    WWhunter's Avatar
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    Ingenious!!
    Don't take life too seriously ... no one gets out alive!

  7. #7
    Dirt911's Avatar
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    Looks great. Is it going on floats?

  8. #8
    Crash, Jr.'s Avatar
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    Ah that makes sense. I didn't know the door swings forward. I'm assuming there's some limit on the doors swing to keep from damaging those rod ends?

    I really like the fuel level indicator for the sight gauge. Nice and simple.

  9. #9
    Utah-Jay's Avatar
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    Looking Good Dave!
    Bearhawk Companion QB Builder
    Revo Sunglasses Ambassador
    https://www.instagram.com/jay_townsend_utah/
    https://www.youtube.com/channel/UCQ0...tBJLdV8HB_jSIA
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  10. #10
    skywagon8a's Avatar
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    Here's a Patrol on floats. Are there any others?

    Click image for larger version. 

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  11. #11
    Bearhawk Builder's Avatar
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    Not yet
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  12. #12
    aktango58's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Here's a Patrol on floats. Are there any others?

    Click image for larger version. 

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    Again, not a mechanic, but Pete, you might be missing a part or three...

    What will your starting point for wing incidence to float be?
    I don't know where you've been me lad, but I see you won first Prize!

  13. #13
    RaisedByWolves's Avatar
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    Dave,
    Looks great. What floats are going on this one?

  14. #14
    skywagon8a's Avatar
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    Quote Originally Posted by aktango58 View Post
    Again, not a mechanic, but Pete, you might be missing a part or three...

    What will your starting point for wing incidence to float be?
    One must have some faith that the plans are correct. These floats have 0.1 degrees more fish mouth opening than my Cub.
    Last edited by skywagon8a; 12-24-2021 at 07:18 AM.
    N1PA

  15. #15
    skywagon8a's Avatar
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    Quote Originally Posted by Bearhawk Builder View Post
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    Quote Originally Posted by Bearhawk Builder View Post
    The doors hinge is at the front of the door. The quadrants stay on the door and swing with it. The rod end bearings have lateral movement in them when 1/4" spacers are place on each side of the bearing ball, this allows the door to be swung open. It does advance the throttle as the door is opened and the belcrank is pulled so the door is placarded "Engine off for left door use". My IA buddy was worried about 'hysteresis' which is the accumulation of small errors resulting in a large deviation however with this arrangement there is zero play or slop in the system. It should work well.
    A thought: It appears the throttle handle hits the top aft bolt as a stop. What would happen if you provided more clearance there and utilized the stop on the carburetor only? Then when you open the door the throttle handle would have room to move and not increase the rpm.

    Sometimes when on floats it is convenient to open the door with the engine still running. And also not want it to speed up above idle.
    N1PA
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  16. #16
    cubdriver2's Avatar
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    I wish the rear float struts had threaded forks to make it easier to experiment

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  17. #17
    skywagon8a's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    I wish the rear float struts had threaded forks to make it easier to experiment

    Glenn
    There are provisions in the rear fitting for this purpose.
    N1PA

  18. #18
    Bearhawk Builder's Avatar
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    Not sure yet Tom, any suggestions?
    Straight float, 2000 lb gross

    Quote Originally Posted by RaisedByWolves View Post
    Dave,
    Looks great. What floats are going on this one?

  19. #19
    Bearhawk Builder's Avatar
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    I see where you're going with that. Actually the carb stop is the limiter and there's a little more movement to the throttle both fore and aft, I made sure of that. I don't think there's enough travel to adjust it that far, it pulls the belcrank about an inch when the door is opened. It's a compromise I know.


    Quote Originally Posted by skywagon8a View Post
    A thought: It appears the throttle handle hits the top aft bolt as a stop. What would happen if you provided more clearance there and utilized the stop on the carburetor only? Then when you open the door the throttle handle would have room to move and not increase the rpm.

    Sometimes when on floats it is convenient to open the door with the engine still running. And also not want it to speed up above idle.

  20. #20
    skywagon8a's Avatar
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    Quote Originally Posted by Bearhawk Builder View Post
    I see where you're going with that. Actually the carb stop is the limiter and there's a little more movement to the throttle both fore and aft, I made sure of that. I don't think there's enough travel to adjust it that far, it pulls the belcrank about an inch when the door is opened. It's a compromise I know.
    What would happen if the throttle was further forward closer to the hinge? The arc travel would be less.
    I like your thinking, I'm just seeing issues when on floats.

    For floats, it's hard to beat a set of EDO 2000s. Alternatively, a set of Montana 2200 straight floats. They have very similar characteristics. The Montanas have a wider flat deck for walking.
    N1PA

  21. #21

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    I have looked at that image of the throttle and my mind sees a frightening scenario.
    There are ways to mount that throttle to the airframe and not the door which would greatly reduce the chance of throttle being opened by someone who is not used to or properly coached to the needed cautions.
    Regards, Charlie
    Super Coupe E-AB build in process

  22. #22
    Bearhawk Builder's Avatar
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    Charlie, elaborate on your idea please. A major requirement for this plane was the ability to have a rear throttle on the left side for 'training' purposes. I could have used a cable that ran under the door frame from the rear and another from the front that connected at some point but that has it's own problems.

  23. #23
    wireweinie's Avatar
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    How about keeping the same rigging between the throttles but use a push-pull cable from the front throttle to carb? If the cable routing was left with some slack, it seems like there should be enough room for the door to open and close. And, as long as the carb end was anchored correctly, the carb setting won't move.

    Web
    Life's tough . . . wear a cup.

  24. #24

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    Attach to airframe then no issues.

  25. #25
    skywagon8a's Avatar
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    The front throttle fixed to the airframe with the other one on the door.
    N1PA

  26. #26
    Farmboy's Avatar
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    Not for nothing, but Dave built it. It’s done, it works well. With better ideas perhaps he will make the next one differently, but only if truly a better solution is found.
    So far all the ideas were discussed and hashed about, and this was the answer.

    It’s okay to build the way it works best for you.

    Pb


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  27. #27
    skywagon8a's Avatar
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    Quote Originally Posted by Bearhawk Builder View Post
    Click image for larger version. 

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    Still thinking. Did you try placing the connecting rod above the two pivots? That may have moved the handle forward instead of
    opening the throttle when the door is opened.
    N1PA

  28. #28

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    If friction lock was on pivot.Handles could move but not changing throttle setting.

  29. #29

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    Looks pretty cool. I’m sure touching it in person and seeing how it works would quiet many questions we have….you can only tell so much from a picture. I like it.

  30. #30
    Bearhawk Builder's Avatar
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    Good thoughts guys, there may be other ways to skin this cat but this made the most sense considering the parameters I was working with. The throttle works perfectly and smoothly with low chance of failure points which was my primary concern.
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  31. #31
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    Click image for larger version. 

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    Quote Originally Posted by skywagon8a View Post
    Still thinking. Did you try placing the connecting rod above the two pivots? That may have moved the handle forward instead of
    opening the throttle when the door is opened.
    Is it awkward to use the throttle if you extended the pivot so it wouldn’t hit the instrument panel, and attached the rear rod whenever you needed it?
    Don’t you just love everyone picking it apart? Once in awhile though you get a good idea out of it.

    Merry Christmas


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    Last edited by RaisedByWolves; 12-25-2021 at 08:00 AM. Reason: Picture didn’t upload

  32. #32

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    Skywagon asked: "Here's a Patrol on floats. Are there any others?

    I plan on putting my Patrol on Wip 2100A's but maybe a while before I get a chance to mount them. Have some repairs to complete. I see you have Father Joe's floats. I was interested in where the center balance point was on the Montanna's? The empty center on my plane is very close to the front wing fitting when level.
    Thanks
    Steve W

  33. #33
    skywagon8a's Avatar
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    Quote Originally Posted by SRW View Post
    Skywagon asked: "Here's a Patrol on floats. Are there any others?

    I plan on putting my Patrol on Wip 2100A's but maybe a while before I get a chance to mount them. Have some repairs to complete. I see you have Father Joe's floats. I was interested in where the center balance point was on the Montanna's? The empty center on my plane is very close to the front wing fitting when level.
    Thanks
    Steve W
    It is step location based upon the average LOADED cg, not empty cg. There is an entire chapter here on seaplanes: "Design for Flying" https://www.amazon.com/Design-Flying.../dp/0070645590
    N1PA

  34. #34

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    Thanks for the reply.
    The thumb rule that I have used in the past was to locate the step 2-2.5" behind the most used operational C of G. That works for most initial float installs but not all. With experimental floats and aircraft, the center of mass should be checked with the empty C of G when mounting floats. Just sayin for safety concerns. If your weighing the assembly for the first time, then you'll find out. Most installs have flown some initial hours on wheels. They are usually close. If you have a flying aircraft, and the gear is changed over to floats, and you have the center of mass/moment for the aircraft, without the wheel gear and the center of mass/moment of the floats, then you can work back the new weight and balance without having to re weigh the whole assembly.
    I was just curious to see where the center mass was on the Montanna's. They are a long narrow float like the Whip's. I don't have enough parts assembled right now to find the center and was just trying to think of where they would position in relation to the fuse. Your posted picture started the wheels turning!

  35. #35
    skywagon8a's Avatar
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    Quote Originally Posted by SRW View Post
    Thanks for the reply.
    The thumb rule that I have used in the past was to locate the step 2-2.5" behind the most used operational C of G. That works for most initial float installs but not all. With experimental floats and aircraft, the center of mass should be checked with the empty C of G when mounting floats. Just sayin for safety concerns. If your weighing the assembly for the first time, then you'll find out. Most installs have flown some initial hours on wheels. They are usually close. If you have a flying aircraft, and the gear is changed over to floats, and you have the center of mass/moment for the aircraft, without the wheel gear and the center of mass/moment of the floats, then you can work back the new weight and balance without having to re weigh the whole assembly.
    I was just curious to see where the center mass was on the Montanna's. They are a long narrow float like the Whip's. I don't have enough parts assembled right now to find the center and was just trying to think of where they would position in relation to the fuse. Your posted picture started the wheels turning!
    Find your average loaded CG both horizontally and vertically. Draw a line 10 degrees aft of plumb from this location. That's where the step is located. Your personal experience can move the step either way some amount. Each airplane's individual characteristics call for different installations.
    The Montana floats are best compared to the EDO 2000s except for more width and their flat decks. The Wips with their squared corners require more considerations for inflight stability.

    Try not to fit amphibs too far forward for CG purposes. The weight of the nose gears being in the front is a drawback.
    N1PA

  36. #36
    wireweinie's Avatar
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    Just for info: If you use a solid linkage, like the throttle linkage in post #1, the only way that will operate without moving the linkage with door movement, is if the pivot point of the linkage is directly in line with the pivot point of the door hinges.

    Web
    Life's tough . . . wear a cup.
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