maules.com wrote:I measured the Maule flap handle at 15" from forward end to hinge bolt.
However the length of the section behind the hinge bolt would also come into play.
Anybody have a description of BH flap mechanism ?

Hey Jeremy,

I didn't measure it, but forward of the hinge point must be about 15". I guessed 12" earlier from memory, but having been and looked, it is definitely more than that.

Of course - like you say, the short bit under the floorboards is also important. As are the horns at the wing root, and the drives at the flaps themselves. All those effect the mechanical advantage.

The splitter tang (Maule may not have this!) from the handle's cable to the individual flap cables also has some effect, because the length of pull changes there due to the Y-cable geometry.

Basically, the system starts from the handle, which connects to a cable which runs aft beneath the floorboards, which then splits into two cables behind the aft bulkhead using a tang. These cables run over pulleys to the flap horns in each wing root, which drive the flap actuators via independant torque tubes (one in each wing). The drive is simply a pushrod connected to the torque tube using an arm arrangement.

I'm glad someone has developed that idea for the Cub. Thanks for the photo. Good on whoever did it, whether it was their idea or mine.

So now, in the same spirit and addressing the original post better... here's another idea that perhaps someone can do, to adrdess the Maule flap system problems that are the original subject of the thread. Obviously this would be prototyped on an experimental airplane first to see if it works, before you start a Field Approval or STC project. I'm not going to do this project, but someone who lives and breathes Maules and likes to modify them would be a good candidate.

Build an overhead flap handle on the center line of the Maule cabin. Make a T-shaped handle tube that's about 18 or 20 inches long, and as wide as the upper longerons.

Weld two tube pivots (slip fit) onto the longerons just forward of the rear cabin cross tube / drag spar carry through. The cross-tube section of the new flap handle rotates in these tube pivots. Have an arm (a control horn, technically) welded on the pivoting flap cross-tube, and connect that arm to the existing Maule flap cable system.

For safety, apply some padding to the flap handle, so it is more padded than any of the exposed airframe tubes that are already in the cabin. The length of the flap handle is limited by making sure it does not interfere with anything else in the cockpit, panel, etc.

About a 45 degree arc of movement should be plenty of travel. Just make the welded arm is long enough to convert this arc into the same net linear movement as the existing Maule system. Even if the angular and linear travel is the same as the stock Maule handle, having more leverage on a longer handle will give you much more mechanical advantage than a 12 or 15 inch lever on the floor. AND, you are eliminating some number of pulleys, bellcranks, etc. compared to the floor mounted system.

I'm not saying this is a weekend project by any means. I'm saying that having full control over the flaps may be well worth the effort if you are flying a real bush plane in real demanding bush plane conditions.

Battson wrote:

maules.com wrote:I measured the Maule flap handle at 15" from forward end to hinge bolt.
However the length of the section behind the hinge bolt would also come into play.
Anybody have a description of BH flap mechanism ?

Hey Jeremy,

I didn't measure it, but forward of the hinge point must be about 15". I guessed 12" earlier from memory, but having been and looked, it is definitely more than that.

It's 13 5/8" from center of pivot to end of pushbutton.

Have you asked Bob Barrows about the difference?

Yeah I did. Bob wasn't able to shed a lot of light as he doesn't have much Maule time to notice the difference. He did say, provided you observe the Vf speeds, you can do a longer handle mod to reduce the flap force, and that some builders have done this. The trick is having a push button / trigger which you can still reach easily.

Glad to see your machine standing wings on and all complete! Join the Bearhawk group on the Community section if you haven't already!

From the picture Zane, the section below the flap handle pivot may be a tad shorter than Maules and the main lever is also a tad shorter, which may be why they are harder to pull.
The later Maule torquetube mechanism is not hard at all, it was the early M4 and M5 cable pull mechanism that was hard if overspeeding flap deflection speeds. Especially so when the added degrees (flap ratchet mod) was used.

maules.com wrote:From the picture Zane, the section below the flap handle pivot may be a tad shorter than Maules and the main lever is also a tad shorter, which may be why they are harder to pull.

I noticed this too. The lower half is shorter to clear the bottom skin. I think this being longer would give more travel at the flap, which I want. But a longer bar has to come too.

Battson wrote:

maules.com wrote:From the picture Zane, the section below the flap handle pivot may be a tad shorter than Maules and the main lever is also a tad shorter, which may be why they are harder to pull.

I noticed this too. The lower half is shorter to clear the bottom skin. I think this being longer would give more travel at the flap, which I want. But a longer bar has to come too.

The lever ratio has to be maintained... You either get advantage or travel. Preaching to the choir, I know. I think about 4 more inches on the handle would do nicely. I may scratch build a new one at some point in the future after she's in the air.