Saturday, July 28, 2018

Turn & Bank Indicator Plumbed to Venturi


 A Turn & Bank Indicator (below the clock) isn't really needed in something like the Fly Baby.  I've accidentally flown into fog and into a cloud.  Both times the Turn & Bank was used to make a controlled turn out of the murk and back to my VFR world.  Therefore, I'm keeping it.  The problem is it's vacuum powered and there is no vacuum source on a C-85 Continental to spin the gyro in it.
 We've used a venturi mounted on the bottom of the plane behind the flange on the cowl.  This is very disturbed air and not a reliable place to operate a venturi.  To help this we've always used a larger venturi than needed to produce the vacuum at 2" of mercury (Hg).  The larger venturi, when properly mounted, will produce more vacuum than the poor Turn & Bank can handle.
 To control the vacuum we used an AN-5829 Vacuum Restrictor. This is just an orifice with a tapered pin so you can adjust it to reduce the vacuum to the desired 2" Hg.  The venturi is connected to the center port, the Turn and Bank to the top port and, a vacuum gauge to the lower port.
 By turning the needle valve in or out you can adjust the vacuum.  It has a lock nut to keep it adjusted once you have it set.  At that point the gauge is no longer needed.  I have other uses planned for the blank space in the panel, so I didn't want to make permanent room for it.  I've made an aluminum bracket (.070" 2024-T3) which allows me to have it installed until I'm happy with the vacuum adjustment, then remove it.  It just bolts to the lower cabane strut fitting.  When it's removed I'll cap the line and secure the end so I can remount the gauge once a year for the annual inspection.  The line fits nicely between the stringers and the fuselage.

 I used Nylon tubing with brass fittings.  When doing that you need the correct, Nylon, crimp ring and, a Tube Support inserted in the tubing.  The support keeps the line from collapsing when squeezed by the compression ring.  Don't use the brass ring it can cut the Nylon tubing.

When the Tube Support is installed you can just see the end of it past the nut.  If you can't see it it may have fallen out while assembling the fitting.  I squeeze the very end of the tubing slightly to help hold it in during assembly.


Monday, July 16, 2018

New Seat Belts and Radio Hooked UP


 I decided to replace the old belts we installed in 1966.  They were surplus military belts and worked fine.  They appear to be made of cotton which definitely deteriorates over time and exposure to Ultraviolet Light. The seat belt was WWII era and the shoulder harness Korean era.  The new belts fit fine except I had to replace the 1/4" mounting bolts for the seat belt with 5/16" bolts.

 Hooking up the shoulder harness required crawling in the fuselage to bolt the brackets back onto the wood structure.  I had a helper stand by just in case I couldn't actually get back out.  It worked out fine.  You need some boards laying on the structure behind the seat.  If I did it again I'd prop up the tail so my head wouldn't be so down hill.

 I made a mounting bracket, for my hand held radio, from a piece of .070" 2024-T3 aluminum.  It's been Alodined and then bolted to the wing attachment bracket.

 I also made a new wooden hand grip, because I lost the old one.  It's carved to fit my hand and twisted to the left for a comfortable right hand grip.  The red button is a Push-to-Talk for the radio.

 The wiring for the button runs down through the stick, with a clamp at the lower bolt to keep the wires out of the controls.

The wiring is also laced to the structure with some rib stitch cord.

 The wiring comes up to a jack in the corner of the panel so it's easy to install and remove the radio.

 The black cable on the upper left of the radio is to the antenna on the baggage compartment.  It's clamped to the strut fitting so it can't fall down the side of the fuselage when the radio is removed.

On it's way back to the baggage compartment, its also laced to the top of the former beside the cockpit.

 I wanted the baggage compartment to be easily removable so I put a connector in front of the door bulkhead.  When it's connected it just hangs out of sight by the stringers.

 There is a male and a female connector.  The male connector has the locking ring on the outside and the pin in the center.

The female connector has a small socket in the middle for  the pin to enter.  The little socket tube is split in 4 segments so it flexes to fit the pin and grips it securely.


 If you are assembling your own connectors follow the instructions carefully in terms of the length to strip the wire, etc.  The picture at the right shows the ground braiding correctly folded over the metal piece.

For some reason the metal piece got pulled off and I put it back together.  The refolded braid wires are no longer gripping properly to hold everything together and I had to start all over.  I was much more careful the second time.

 The cable inside the baggage compartment is clamped to the frame and taped to the metal shell.  I turned the clamps around so the cable is as much out of the way as possible.

The handheld works fine with it's own antenna but even better with this antenna.


Sunday, July 15, 2018

Baffles and Hot Air Ducting Installed


 The forward baffles are reinstalled.  One change I am going to make is to replace to elastic stop nuts I used with heat resistant lock nuts.  I don't know what I was thinking when I used them.

 There is a small baffle between the lower fins of the 2 cylinders on each side.  The lower ends of these baffles are held snug to the cylinders by a spring, long ago lost.  I found some springs at the hardware store made from .022" wire which should work fine.  A very slightly stiffer spring would be nice but these do hold the baffles.
 The 4 springs are a bit of work to install.  It's easy to hook one end to a baffle, but fishing it past the cylinder and hooking the other end to the baffle on the other side of the cylinder took many tries.

If I were doing it again I'd make a long skinny loop with safety wire to fish through, hook the loose end and pull it past the cylinder.

 A new air filter and CAT tubing gets this looking like a finished engine installation.  The carb. heat tubes on the right were the easiest to install.
 I never checked to make sure the inlet tube on my cabin heat muff actually fit into the CAT tubing.  I had to use my fluting pliers, like on the edge of the firewall to shrink it slightly.  If the muff works I plan to weld up a more permanent one so I'll be sure to make the inlet the correct diameter.

I still have to finish the primer lines.


Thursday, July 12, 2018

Exhaust Pipes Back On with Spiral Wound Gaskets


 I had a little trouble getting the pipes back on.  The first couple threads on 2 of the studs were just a little tight fitting in the nuts so I couldn't get them started with my fingers.  These were also the 2 hardest nuts to reach.  I finally go them on and properly torqued, with oil on the threads.
 One of the nice improvements was in the exhaust gaskets which came in the set.  The old ones were copper with an asbestos core.  The asbestos took care of the heat and the copper protected the asbestos from the flow of hot exhaust gasses.  There is a piece of thin sheet copper on each side of the asbestos.  The inner edge of copper is the same thin sheet formed like a grommet overlapping the copper sheets on each side.

Even though the gasket is crushed between the cylinder and exhaust pipe flange the vibration on the pipe is enough to allow it to wiggle and slowly destroy the weak asbestos.  Eventually some of the asbestos works out from between the layers of copper, the inner ring of collapses and the joint leaks.

The new ones have an 1/8 in thick steel frame which takes the compression load, so the joint can't wiggle, while the inner gasket just has to maintain the seal.  The inner gasket is a soft Spiral Wound metal which compresses to the thickness of the steel frame to form the seal. I really like the design.  The Continental torque spec. is based on using this style gasket.



Tuesday, July 10, 2018

Engine Controls Hooked Up


 Some great weather for Independence Day has allowed me to get some more work done on the plane.  The Carb. Heat cable is finally hooked up.  The gable is clamped to the diagonal tube on the engine mount with 2 cable clamps at a right angle to each other.

 The throttle cable is hooked up with the cable clamped to the tube in the same way, but I had several issues.  I forgot to put a hole in the new baffle I made, so that had to come back off.  I knew it was needed, just forgot to make the hole.

 The next thing I discovered was that the cable didn't actually reach the lever on the carburetor.   All my neatening up of the holes in the firewall was done with the engine removed. First I moved it down where the carb. heat cable came through and made a new hole next to it for the carb. heat cable.  That was a good plan, but while the cable reached the lever, there was no way to clamp it to the engine mount so it would work properly.
 The final solution was to move the hole closer to the center of the firewall, more of a straight line from the throttle quadrant to the carburetor.  That worked, so I move the carb. heat cable back where it was and covered the 2 wrong holes.  So much for my fresh new firewall.

I moved the clamp in the cockpit from under the fuel shut off valve to the inboard mounting bolt of the valve.  I also tied the cable lightly to the fuel line to keep it clear of my foot when entering the cockpit.  It all works in the end.