Designing a Lift & Latch Mechanism

Fabricating the Turtledeck 2 of 3The plans do not show how to lower and lock the turtledeck down or how to lift it and keep it  up.  As an Interior Designer (my regular occupation) I have designed a lot of specialty store fixtures, concierge desks, etc., so I decided to use a lift mechanism typically used to raise and lower custom tables made by Suspa in Grand Rapids. It is a manually operated self contained (non-electric) single acting cylinder system and hydraulic pump.  I located the pump under the sheet metal deck of the turtledeck compartment with a detachable crank handle facing out on the pilot side.  You crank it clockwise to raise the turtledeck or counterclockwise to lower it and it will stay put wherever you stop cranking.  I bought a complete second system just in case it ever failed but to my surprize it has been remarkably dependable after being raised and lowered hundreds of times during several hot and cold seasons.

Another concern was keeping the turtledeck locked down for flight. You obviously don’t want something 8 feet long flopping around back there.  An architectural panel latch available from Southco was used to latch and lock the front and rear ends of the turtledeck. This mechanism uses two detachable hex wrench operated  thru-bolts that when rotated hook to brackets and pull and lock down both ends of the deck.

At this point in time I had my first visit from my EAA Tech Advisor, Bud Potts who offered a lot of technical know how and made many other visits throughout the building process.  All aircraft builders should take advantage of this useful EAA resource.

Learning to Weld

Welding ProjectsWith the fuselage securely attached to the rotisserie it was time to learn to weld the 4130 steel tubing.  Using a oxygen/acetylene gas rig and jewelers torch I test welded several scrap pieces together but it was’nt until I got expert instruction from Chuck & Craig Garret from my local EAA Chapter 145 that I finally gained some confidence.

I started welding on the fuselage lift handles and then the wing spar brackets, elevator bell crank assembly, floorboard mounts, rudder pedal mounts, engine mounts and landing gear and wing strut brackets.  They say the best way to test a weld is to try to tear or break it apart.  Unfortunately that destroys your weld.  Sadly, a few years later I put some of my welding to a real world test during a bad landing/ground loop event.  The good news is, the welds survived – the bad news is, the landing gear did not.

I will post more about that event in a future post including photos of the damage and the repairs made to the aircraft.