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Monday, September 15, 2014

Brake/Rudder pedals - part 6

Pedals, pedals, pedals! (12.0 hrs)

I started the day machining the last few steel pieces I didn't get to do last week.

The first parts I worked on were the hinges for the pedals, these were merely steel cylinders to be welded at the bottom of the pedals' vertical tubes.

Testing hinge for proper fit

Same hinge on bottom of pedal's tube, where it will be welded.

My good friend and Long EZ builder, Walter brought up a valid point about my original rudder cable attachment design. His concern was that the constant back and forth motion of the pedals might work loose the bolt securing the rudder cable adjustment tab. Walter has the gift for finding the most unusual failure modes, and this time he had me worrying about it as well, so I ended up modifying the design from a bolt, to a fixed stub and a cotter pin.

New rudder cable attachment point design

This new concept required additional lathe and mill work.

Drilling the cotter pin hole to 0.067" (1.7 mm) 

Rudder attachment point completed

The way I planned on adjusting the rudder cable to compensate for pedal adjustments, was to make a steel plate with holes every ½(1.3 cm), matching the adjustability of the brackets. The plates would connect to the pedals via the pins I just made.

0.063" (1.6 mm) 4130 steel sheet on the "chopping block"

Machining action shot

Plate as it came off the mill...

... and after a little cleanup.

This is how the plates will connect to the pedals

With the plates done, all the pieces were finally on hand, and the time had come for putting them together.

Let's make some pedals!

With all the design changes I have made thus far, the brake/rudder assembly looks quite different now, so before we move forward I’d better show you its latest incarnation...

Left pedal, seen from the left fuselage sidewall.

Same thing, opposite view.

The welding session took all afternoon, and preheating the thicker steel parts made them a lot easier to weld, as I had anticipated.

I started by welding the pedal hinges...

This hinge is getting ready to be welded. The hinge in the background is already welded.

View of both hinges welded

... then the rudder cable connectors to the actual pedals...

Preheating the much thicker end piece

Completed weld still glowing

Both pedal tops done

... followed by welding the pedals to the pedal’s shafts...

Magnet holding tubes in proper alignment

Finished pedals

...and lastly the pedal’s flanges...

Well... actually these are the completed pedals.

After letting them cool down a bit, I put them all together at last...

... then sat them down in the fuselage to see how they fit...

Looking for the perfect place to put them

Left side

Right side

Now, I have two options as far as how to position them. 

Option 1: I can lay them along the sidewalls, affording me more room to stretch my legs in flight (good).

Looks odd, but feels pretty good.

A view from the front seat

Option 2: I can lay them parallel to the aircraft centerline, allowing my feet to be straight when pushing on the pedals (good) but reducing the space I have to get around them in flight in order to stretch my legs (not so good).

Reduced space for getting past the pedal

Looks more "normal" perhaps

This configuration wastes a lot of space

I don’t know. What do you think?

Should there be a third option perhaps?

So far I have only tried option 1, and it feels pretty good. The bottom half of my legs rest against the sidewalls quite naturally, my heels brace against the F-22 stubs that stick out of the floor, and my feet act on the pedals parallel to the master cylinder shaft.

I’ll do more testing this week, after I get back from Ireland.

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