Chapter #16,  Landing Gear Mechanisms,

MODIFICATIONS:  I tried to stay close to the original design for the hand crank for my retraction system.  I personally wanted to stick with the manual system because I felt that hand cranking would develop a "feel" for the system and thus a "feel" for if something was not quite right.  In my trouble shooting I have found that the front gear would sometimes hang up on the gear doors, and sometimes hang on the FLG steering cables.  If I was using a motorized system the motors would have ripped things apart.   I modified the crank itself by creating a lever that unlocks both the front and rear gear simultaneously and in one action.   I additionally changed the front gear unlocking mechanism from a cable and spring set up to direct push/pull tubes.  The over center lock on the rear gear has remained basically the same with some parts being machined that had been previously welded up.
NOTES ON PLANS:  Its been quite awhile since I built these parts, and I don't currently have the time to go over them before typing this out so I'm likely to be a bit inaccurate here.  From what I remember the plans show way too much information about the gear system on a single sheet of paper.  It is also my opinion that somebody, who did not know enough about the operation of the systems, went in and modified the drawings.  What is shown is not entirely clear, and does not represent Spences usual drafting skill.  The sheet includes several revisions, and some of the items simply do not make functional sense.  Items have been sketched in but the plans present no "clear" and definitive system for the retraction and locking.  I did however have an old set of plans that did show the old gear crank system complete with modified sears ratchet wrench,. this older set was more clear.
NOTES ON ASSEMBLY:    Please also look at the images in Chapter #9 Real Landing Gear, and Chapter #8 Front Landing Gear

Front locks-  The plans show the front locks as spring loaded hooks in the front of the landing gear track with cables running aft through the gear well and connecting with the unlock lever.  My Locking hooks are in the same position but I run their shaft through the side of the gear well and into the nose section of the hull.   I did this to have less parts in the wet gear well.  I now have my return spring, and micro switch inside the hull away from the water.  Downside is that it is harder to get to for inspection and repair.  From there the unlock Hook/Lever joins a push pull tube and goes rearward to an intermediate shaft that is mounted on the aft side of STA# 33.  Then a second push/pull rod connects the intermediate shaft with the un lock lever.  Some of the benefits of doing it this way is that the action of the gear moving forward and pushing its way under the locking hooks causes the unlock lever to physically move.  When operating the gear, when the FLG is going into lock position, the handle rises and then falls back down to the neutral position.  If the front gear doesn't lock the handle doesn't go back down.  This is a visual clue that the FLG is not locked (there are also lights to show gear position and lock).  The only real downside to all of this is it probably weighs a touch more.  It may sound more complex but with the cables you would need more pulleys and a method to seal up the gear well, plus some more springs.  I think this is an improvement and it seems to work very well. Lock at FLG Locks Backside with Switch Intermediate Shaft, STA #33

Crank Assembly/Lock-  The early stock crank assembly used a basic nine tooth sprocket to crank the gear chain and  a small modified Craftsman ratchet wrench to manage cranking the system one direction or another.  The wrench also held the gear in the up position.  It had to do this because the rear gear legs would hit the wing strut before the RLG over center lock would kick back over center.  By shortening the length of the RLG over center link , and changing the position of the locking pin hole drilled in the gear tube, the landing gear system will lock in BOTH the up and down position.  Unfortunately I cannot remember exact dimensions.  I do not think the current crop of plans show this correctly,  I do remember spending quite a bit of time working out the geometry to get it right.  And even after I had it built I wasn't confident that the tires would not hit the wing strut until I had the wings and gear mounted to test it all out (it is perfect!).  I welcome anybody who needs to duplicate dimensions to visit and take all of the pictures and measurements they need.     So with the modified rear locks I basically had a crank that no longer needed the ratchet, and would simultaneously crank the front and rear gear into a up/locked and down/locked position.  I  now only needed to add a unlocking mechanism.  The stock plans show cables going directly to the rear over center link and pulling on it to unlock it.  This will not work as the unlocking cable will prevent the over center link from moving aft as the gear is cranked into the up position.  This is a ridiculous drawing, I have a hard time believing that Spence drafted this.  The ONLY place that the cable to unlock the over center link can come from is one that is approximately equidistant from the link in BOTH the up and down positions.  The only logical place is at the base of the OCL pivot point at the keel.  This IS on some of the old drawings.  From there, some lever needs to be constructed to kick the OCL out of over center.      My solution basically has a unlock handle/lever that pulls a cable that runs to the base of the over center link arm, and then a cam like lever kicks the over center link out of "over center"  (this last item is well photographed in the RLG chapter)  The same handle/lever is directly connected to the front landing gear unlocking push pull tube.  It took some time to work out all of the geometry but the system works well.  I believe that this is how Spence "wanted" the system to work.     There is one remaining missing piece to this puzzle.  As my story stands, you would need two hands, one to pull the unlocking handle and another to crank the gear while holding the handle in the "unlock" position.  The early drawings solve this by having a small tab that would hold the unlock handle in the unlock position once you had lifted the handle.  You would then proceed to crank the gear a little bit and then manually release the unlock handle to a neutral position.  If your counting that is four steps 1- lift unlock handle, 2- crank some, 3- release handle, 4- crank the remainder of the way.  When the ratchet was involved it required even one more step.  God forbid you were in a hurry!  I wanted to make this a two step operation: 1-  Unlock gear, 2- Crank.      I did this by making the Unlock handle automatic.  Its tough to describe so study the pictures as well.  Basically when you pull then unlocking handle up, a spring loaded "toothed locking key" engages the handle and holds it up in the "unlock" position.  It remains in that position until the crank handle swings by and hits a tumbler on the key that swings the "locking teeth" out of the way allowing the unlock handle to drop free.  The timing of this has to be so that you get  a 1/2 swing of the crank before it frees the unlocking handle, otherwise the system will just jump back into the locked position.  Yes it is a little bit like building a better mouse trap, but it works elegantly once set up correctly.  I would think that if it were planned out and drafted instead of AdHoc'd together it would work even better. Overall view Handle UP, UNLOCK Handle DN, LOCKED Under deck of Unlock Handle

Intermediate Chain Shaft-  I did not modify this much, the exception being the gear ratio.  The old plans called for a 17 tooth rear chain sprocket and a 18 tooth front chain sprocket.  After working all of my stuff out I ended up with a 22 tooth rear sprocket and a 25 tooth front sprocket.  This provided the ideal ratio for my system, one factor that could easily change this is having a longer or shorter travel on the Front Landing Gears suspension.

Rear Modifications-  The rear system was changed so that the RLG would lock in both the up and down positions.  This prevents air loads from putting stress on the chain system in flight.  It only requires a slight shortening of the over center link (OCL), and either a rotation of the hole as drilled in the Main tube, or a locking pin with an offset hole.  The issues that change the geometry in the RLG system are the length of the OCL, the height of the hole as drilled in the pin, and the position of the hole in the RLG tube.  I apologize but I do not have any dimensions in my notes.  In addition the the changes in the OCL I made my unlocking mechanism by running the unlock cable down to the hinge point of the OCL (at the keel) and making it actuate a cam higher up on the OCL that kicks the OCL out of over center.