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#avgeek

124 posts58 participants2 posts today

I actually had three more short videos from my flight yesterday that I missed in my little compilation. These are from my flight yesterday and show much closer cloud surfing from the morning.

Caution: May have loud engine noise

Glider flight controls - rudder pedals and cables.

The rudder pedals pivot at the bottom and pull on steel cable that runs along the fuselage sides, in plastic tube jackets, all the way back to the rudder. (This steel cable can handle about 1,000 pounds before failing. My legs will never generate that much force.)

Note the "S" tube on the sides of the pedals. When pedal position is adjusted for different height pilots, the S tubes mean that the rudders maintain the same orientation, and the steel cable is unitary...one length. Simple, yet effective.

(The seat/floor pan is not present in this photo.)

Glider flight controls.

This video shows operation of the spoiler control lever, which is also the wheel brake control. Note that there are two push-pull tubes connected to the lever.

For most of the lever travel, the wheel brake is not engaged. Note that this push-pull tube has a telescoping sliding coupling that is set up so that the master cylinder is not compressed until almost the very end of the lever travel. Also note that I pause briefly at the point where the wheel break master cylinder first gets compressed.

The second portion of the video shows the control levers, aft of the landing gear box, that will ultimately be connected with bellcranks that are attached to the wing roots.

This is a simpler system than the flaperons.

Glider flight controls. How does the control stick make the ailerons work? (And what about those flaperons?)

The video is in three sections. (Sorry about the abrupt jump cut edits.) First section shows the control stick moved side-to-side to move the ailerons. That motion is carried by various push-pull tubes and bellcranks...aft of the landing gear. In the second section of the video we see the lever for one wing goes up while the other goes down.

But I have flaperons, not ailerons. The third section shows the result of moving the flap lever...the same wing control levers now move up together, or down together.

The mechanical mixer allows two different control inputs (control stick sideways motion, and flap lever) to be combined into one final motion.

en.wikipedia.org/wiki/Flaperon

en.wikipedia.org/wiki/Bellcran

This completes what was started here:
universeodon.com/@KrajciTom/11

Continued thread

Installed the new rudder links! It’s so much better. I actually moved my seat back one tab (third image shows the copilot seat, which is all the way back. The pilot’s seat is now at the center position).

Only downside is that my rudder lock is slightly less effective. It’s really easy for it to slide up on the control stick now. So I’ll use the seat belt to hold the stick in place, which wasn’t necessary before (though still a good idea).

After a few times taking the United Express (GoJet) CRJ550 EWR-DCA shuttle, I was upgraded this time to the goofy seat (4A) with my only rowmates being luggage and the FO's jacket. #avgeek

Replied in thread

@Jgbird

This photo tells us something important about aerodynamics for wings.

Look at the tip feathers. They are hardly bent, and feathers are flimsy. There is no lift being generated at the bird's wingtips.

My glider generates lift at the tips...and because of that my glider needs a rudder/vertical fin in order to turn.

Birds don't have vertical fins/rudders, but they turn just fine.

youtu.be/Hr0I6wBFGpY?t=238

en.wikipedia.org/wiki/Prandtl-

The kind of wing the Wright Brothers used...made a rudder/vertical fin mandatory. We had to unlearn that in order to make a plane that flies like a bird.

Continued thread

I got confirmation from @Leighton that he safely arrived at home in Melbourne🇦🇺. So the trip was a complete success. Lots of #avgeek / #spacegeek sights. Some national parks & monuments visited too. (More pics in this thread.) A great time had by both of us. Also for me it's a relief that my turn as guide in his USA trip worked as well as his turn as guide for my trip to Australia during their Summer. Thanks @hanscath for flying us on a Bay Tour. Thanks @JetCityStar for Seattle MoF tour. #travel

Glider flight controls!

This is only part of the entire system. It is one of the more complex parts. This portion of the system changes camber of the wing flaperons. Please read the alt-text for more details.

One important part of this subsystem is the use of a push-pull cable, which is rather different from the cables you typically find on bicycles. (See the first comment to this post for a photo of the push-pull cable.)

I will post other videos that show other portions of the mechanical flight controls.