Bearhawk Patrol

[Bearhawk Builder]

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.

 

[Chesney]

The plane looks amazing in these photos, and yet somehow looks even better in person


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[Crash Jr.]

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?

 

[dirthog4]

Bearhawk doors open like a car door?

 

[Bearhawk Builder]

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.

 

[WWhunter]

Ingenious!!

 

[Dirt911]

Looks great. Is it going on floats?

 

[Crash Jr.]

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.

 

[Utah-Jay]

Looking Good Dave!

 

[skywagon8a]

Here's a Patrol on floats. Are there any others?

 

[Bearhawk Builder]

Not yet ;-)

 

[aktango58]

Here's a Patrol on floats. Are there any others?

View attachment 58974

Again, not a mechanic, but Pete, you might be missing a part or three...:smile:8)

What will your starting point for wing incidence to float be?

 

[RaisedByWolves]

Dave,
Looks great. What floats are going on this one?

 

[skywagon8a]

Again, not a mechanic, but Pete, you might be missing a part or three...:smile:8)

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.

 

[skywagon8a]

View attachment 58944

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.

 

[cubdriver2]

I wish the rear float struts had threaded forks to make it easier to experiment

Glenn

 

[skywagon8a]

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.

 

[Bearhawk Builder]

Not sure yet Tom, any suggestions?
Straight float, 2000 lb gross

Dave,
Looks great. What floats are going on this one?

 

[Bearhawk Builder]

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.

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.

 

[skywagon8a]

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.

 

[CharlieN]

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.

 

[Bearhawk Builder]

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.

 

[wireweinie]

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

 

[dirthog4]

Attach to airframe then no issues.

 

[skywagon8a]

The front throttle fixed to the airframe with the other one on the door.

 

[Farmboy]

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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[skywagon8a]

View attachment 58944

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.

 

[dirthog4]

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

 

[Dan Gervae]

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.

 

[Bearhawk Builder]

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.