Hummel Bird

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Glen Maxwell

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Dec 18, 2019
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36
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Lake City, FL
The gear legs are very different from taildragger to tricycle. Tricycle gear are at a 13 degree angle behind the spar, taildragger are 26.4 degrees to the front, the through bolt and the bottom mounting plate will be at the wrong angle if you flip them. In addition, the vertical stabilizer spar is longer on the taildragger to mount the tailspring support clamp, the rudder coupling is different, and there are tailspring support plates on the rear fuselage. The engine mount is different to support the nosegear, as well as the rudder pedals for the nosewheel steering.

Not insanely complicated, but not an easy swap by any means. Most of the welded parts would need to be built or purchased.

The assembly manual and video are not needed for any of this, it is all on the plans.
Thanks 12notes, exactly the information I was looking for.

Thanks also to Turd and Karmarepair
 

Glen Maxwell

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Joined
Dec 18, 2019
Messages
36
Location
Lake City, FL
OK Guys, another question, I'm getting ready to go pick up the Hummel Bird and need to know the wheel base of the main mounts to the out side of the tires. Anyone know that dimension?
Cheers
Glen
 

12notes

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Outside of the tire to outside of tire on mine is 77.5". Might vary a bit with different constructions, my gear was built mostly to plans, except I bought the Tracy O'Brien hydraulic brakes/axle/receiver and welded it in. Looking at the plans, for some reason the tricycle gear mains have axles 1/2" shorter than the taildragger on the plans, so your might be an inch narrower than mine.
 

pwood66889

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Feb 10, 2007
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Sopchoppy, Florida, USA
"...for some reason the tricycle gear mains have axles 1/2" shorter than the taildragger on the plans, so your might be an inch narrower than mine."
Like you, 12Notes, I wonder why an axle (presumed from the main gear leg to a nut on the other end) would be a half-inch shorter from conventional to tricycle gear. The weights may not be exactly the same, but they need to be close else the "tail power" to change angle of attack would fall short on one or the other. Where is the length? In the wheel bearing? Between the bearing and where the axle is welded to the gear leg??
All I can see is that the rotation should be less in a tricycle because less angle is needed to get the right lifting power. That is to say, the number of degrees from riding on a tail wheel to lift off angle is more than going from nose wheel close to level to tail down for that same angle. Maybe?
Just curious.
Percy in NW FL, USA
 

Glen Maxwell

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Dec 18, 2019
Messages
36
Location
Lake City, FL
12notes, would you mind looking at your plans and telling me what the distance is from the centerline of the nose wheel to the centerline of the mains?
Cheers
Glen
 

12notes

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12notes, would you mind looking at your plans and telling me what the distance is from the centerline of the nose wheel to the centerline of the mains?
Cheers
Glen
The plans do not give that dimension. The main gear axle is 6.5" behind the front surface of the spar. By my calculations (the plans don't have this dimension either), the nosewheel axle should be 5.75" in front of the firewall. The front spar is located by clamping a rib to the front and rear spars, and the rear spar is located at the bottom of the opening in the angled bulkhead C, calculating the actual distance between spar and firewall is a problem I don't want to tackle at the moment, and measuring mine wouldn't help as I used a different airfoil with a slightly different front spar placement.
 

Glen Maxwell

Active Member
Joined
Dec 18, 2019
Messages
36
Location
Lake City, FL
Does anyone have William Spring's "Hummelbird Build Video"? It is no longer available from Hummel Aircraft nor is it in their Build Video Library. Would love to get a copy.
 
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