Chapter 16: Control System


Some General Comments:

 

Chapter 16 is the easiest chapter to complete, but I personally think that doing the following things would make it even easier:

  1. It would be easier to install the forward and aft controls (the tubes inside the fuselage) after Chapter 12 while you can still turn the tub onto its side.  I would wait to drill the CS121 and CS122 firewall crank tubes until I finished the aileron controls.

  2. I think the steps are presented backwards for installing the aileron controls.  I found my process of starting at the ailerons and working my way to the firewall to be much easier.  I locked out the ailerons into their neutral positions, set the CS132 aileron crank, built the CS129 push-tubes, set the CS128 bellcrank , built the CS126 push-tubes, then finished with the CS125 tie-rod across the firewall.

  3. I waited until Chapter 16 to drill out the holes in the seatback and landing gear bulkheads.  What a mistake.  It would certainly be easier to have drilled the holes in Chapter 4, and only tweak the hole clearances in Chapter 16. 

  4. I admit it might, might, might be easier to build the forward armrests after the controls are fully functioning.  I built my consoles after Chapter 13 and before I built the wings and ailerons.  I blindly built them to plans, but still had interference issues with the control sticks.  The bottoms of the control sticks were hitting the insides of the forward armrests.  I ended up biasing the handles inward a bit and redrilling the CS121 and CS122 tubes.  It certainly is easier to shape the forward consoles to conform around the movements of the control stick, but I don't see how I could have anticipated this by doing the Chapter 24 armrests before completing Chapter 16 controls.  I thought if I followed the plans for the armrests I'd be okay, but no............

There have been some changes to materials and parts list for Chapter 16:

  1. The chapter materials kits ordered from Wicks (I don't know about Aircraft Spruce) are now supplied with four plastic swivel bearings instead of phenolic material.

  2. All rod end bearings and rod end fittings are now MM-4's and CS1A's instead of MM-3's and CS150's.  Remember to request this change when ordering the chapter kits from Wicks (or Aircraft Spruce) and Brock.  Nat issued this change after RAF issued the change for the Long EZs.  It seems a Long EZ flyer had bent an MM-3 when removing his wing.  He simply bent it back straight and went flying.  The bearing eventually broke in flight. 

  3. All of the Brock-supplied bellcranks for the aileron controls are drilled to accept AN-3 bolts.  Because we've changed to MM-4 rod end bearings, we now need to use AN-4 bolts instead of AN-3's.  So you'll need to enlarge the holes in the CS122 firewall cranks, the CS128 bellcranks, and the CS132R aileron cranks.

Don't cut your tubes until you've had a chance to measure and verify their lengths.  I discovered several issues with the lengths specified in Schedule B on Chapter 16, page 1:

  1. Be aware that the plastic swivel bearings are thicker than the phenolic bearings they are to replace.  I had to change the lengths of the forward control tubes and inserts to keep the control stick at the FS location specified in the plans.  I figured out the new lengths by studying the large M-drawings.

  2. Two of my tubes -- the CS136 (shorter canard push-tube) and CS129 aileron push-tube in the wing root -- did not match the lengths specified in Schedule B (Chapter 16, page 1).   This comes as no surprise since our drawings and our text have never been updated to reflect the new AN-4 rod ends and the CS1A rod end fittings we're now using.  The processes I used for the canard and aileron push-tubes include the how-to's for determining the exact lengths. 

  3. Be aware that the Chapter 16, page 15 drawing may be a carry-over from the Cozy III drawings and may not have been updated for the longer Cozy IV wing root.  So don't use it as a full-sized drawing.  (Nat told me that.)   Also, the page 16 drawing is not meant to be used full-sized either.

  4. When I finished rigging the control systems, I measured all tubes and recorded their lengths in my plans.  I also denoted the M-drawings and Chapter 16 drawings to reflect the final configuration, including the new bearings, rod end fittings, and control stick cant angles.

Some general things to be aware of:

  1. Make sure you use a good drill press and some sharp drill bits.  Dull drill bits will gall the aluminum and drag the thin, aluminum wall into the hole you're trying to drill into the steel inserts (or universal joints).  The aluminum tube will attach itself permanently to the insert, meaning you won't be able to remove the steel inserts.

  2. Be careful when handling the universal joints.  Itís easy to dislodge the orange rubber protective boots and itís easy to inadvertently squeeze out the grease thatís in there.

  3. The steel inserts will rust in a hurry, and the rust is accelerated after being handled with sweaty, grimy hands.  I painted the steel tubes with a light coat of zinc chromate.  I wanted to alodine the aluminum tubes, but just never got around to ordering the alodine chemicals.  So I just painted them with zinc chromate after I drilled all the holes just to make them look good. :-)

 


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