Bicycle hooks: Don’t use bicycle hooks to hold up the fuselage cage! When you put some weight on them, they will straighten out and ruin your day. We used conduit beam clamps attached to 3/8″ threaded rod 36″ long. The rod either can go through holes drilled in the hanger 2×6 or you can use the angles from the wing jig. The rods also allow precise leveling and height adjustment. When it is time to hang the wings, the gantry can then be moved forward to pick up the instrument panel tube. This allows leveling for wing alignment while it gets the gantry out of the way of the wing.
Caution: Re: Bike hooks bending when working inside the fuselage: (eg bulkhead B). Mine did too, and I found it necessary to re-bend and re-level fuselage after Bulkhead B, before lining up rudder, etc. Thus I found it important to “safety” the fuselage by installing “S” hooks and chain bolted to my cross beam to avoid future such problems.
Moving the fuselage: Fuselage up & down – Rather than use the bicycle hooks and frame as outlined by SH, use an engine hoist rigged to the fuselage cage cross member between the forward wing attach points. I used a 2×4 and rope. A few strokes of the hydraulic lift allows you to position the fuselage from 6 inches to 3 feet effortlessly. Adjust the height to suit. Leveling horizontally is done with 2 eye hooks in the overhead joist, chain, S hooks and a turnbuckle on one of the chains. A few turns of the turnbuckle adjusts level. A bubble level taped between the forward gear sockets checks level at a glance. You don’t have an engine hoist? You’ll need one to install the engine. Discount outlets are selling them for under $200. A rope sling around the fuselage forward of the vertical stabilizer hooked to an overhead chain hoist, pulley or rope to an overhead eye screw provides longitudinal leveling and adjustment for waterline. Tape a 4 foot level at the waterline for level at a glance.
Fuselage rotation – Make a plywood jig to fit the firewall and bolt it to the firewall using the 5 engine mount bolt holes. Center the rotating portion of an engine stand (engine stand holds an engine for overhaul and allows you to rotate an engine) and bolt it to the plywood. I had to use a short piece of 2x under the engine stand device and plywood to give clearance. Hook a chain around the central pipe of the engine stand and hook the chain to either an overhead chain hoist or engine hoist. I used a bolt to make sure the chain didn’t come off. Use the above described sling around the tail. You can now lift and rotate the fuselage. You can single handedly invert the fuselage to glass the dorsal seam or turn the fuselage side to side to glass hard points. Fiberglass goo dripping on your head is no fun. Once your finished the rotation jig you can put it on or take it off in a few minutes.
Fuselage back & forth – I rigged up an overhead gantry system using 2″ barn door track mounted to the overhead joists. I used an eye bolt through the trolley which is used for the door. Use your chain hoist or pulley hooked to the eye bolt to move the fuselage back and forth. I already had this gantry system in my shop and have used it to move heavy projects around. It saves your back.
Fuselage mounting: All of the bulkhead work and the rudder fitting was done with my fuselage supported on two five-eights x 6″ hardware store bolts mounted through the wing strut fittings. Bolt heads are recessed in the top of a 6×6. This puts the tail about 2 feet off the ground. In this position the fuselage is easy get in and out of for bulkhead B, easy to level with the bolts, and puts the tail spar/rudder work at a convenient height.
Fuselage leveling: To ease the process of leveling the fuselage in the future, I body puttied a bullseye level on the bottom of the fuselage in the seat pan area after getting the fuselage level. This may or may not be as accurate as using the waterlines and cage but it will get the fuselage very, very close to level in each axis, within a few tenths of a degree.
Cage-fuselage shell alignment: The sequence of steps for initial alignment of the cage inside the fuselage shell did not take into consideration proper alignment. In step 22 it outlines the use of a string to line up cage centerline and rudder centerline, this step should be accomplished prior to locating and drilling tab attachment holes in the fuselage. In addition, for further accuracy we strung a tape measure from the aft wing attachment template to the plumb bob string which is attached to the top of the rudder as outlined in step 22 To achieve maximum accuracy for this critical alignment. I have observed on several completed GlaStars that the wing root faring is misaligned particularly in the forward most portion by hanging down and forward 3/8″ to 1/2″. This problem needs to be addressed prior to step 18 When the bolts are removed from the wing root templates it is imperative that the wing root faring remains in the same position as before the bolts were removed. In my conversations with S-H they suggested letting this faring hang down 1/8″ below the template in the forward section of the faring, to be rectified by pulling the faring up into position prior to installing the turtle deck. The reason being that I was unable to raise the wing root faring to its proper location without undue stress and considerable pressure to the shell even though all of the tabs on the fuselage shell were making contact at the same time. My conclusion to this problem is that either the cage is too big for the shell or the fuselage needs to be modified to facilitate easier installation and better alignment of the wing root faring with the wing.
–Danny – GlaStar Component Service
Answer to the above: When the cage is adjusted down to its lowest postion, the forward, lower (firewall) tabs should be down all the way with only one shim beneath them. At this position the wing root fairing remains approximately 1/8″ below the alignment jig at the leading edge. Do not attempt to get the cage any lower as it will result in eventual difficulty lining up the spinner with the cowl (engine too low).
The difficulty you are experiencing in raising the wing root fairing goes away once the fairing has been fully relieved to accept the main spar end. Once you have gound out the vertical fiberglass for the span, the leading edge of the fairing can be easily lifted upward and held in an aesthetically optimum position when bonded to the top deck in a later step. The wing root fairing gap to the wing can also be adjusted side to side by increasing or decreasing shims under the door post attach tab, while the rear portion is adjusted when drilling the structural attach bracket through the steel flat tab.
A little history: The GlaStar was originally designed as an all composite aircraft and later improved to a steel cage in a bottle. It was a real challenge welding the original cage with mirrors and very limited space! Considering the difficulty, we came out P.D.C. (pretty darn close). Final adjustments in the wing incidence were also part of the culprit for the slight mismatch (we’d rather have it fly right). I’ve personally helped drill and align four cage fuselage assemblies so far. The wing root fairing is easily dealt with.
Implications for skid due to folding wings: After folding the wings on the prototype GlaStar (thousands of times as a trike and 40/50 times as a tail-dragger) here’s a couple of thoughts:
AS A TRIKE: With full fuel and no baggage our prototype would remain on its nose wheel with one wing folded. It takes very little downward pressure, however, on the tail to lower the tail down to the ground. Once down, it will remain there on its own. (CG has moved to the rear of the main wheels.) Upon folding the second wing, if you left the trike on its nosegear, the tail will start descending about halfway through the wing fold. I have held the tail up by simply lifting on the second wing as I completed the wing fold. It didn’t seem all that heavy to me, however, it usually puts the tail on the ground. With weight (up to 250 lb.) in the baggage compartment sometimes with the first wing fold it simply goes on its tail that much sooner. Still it remained very controlable. A simple skid is a good idea. In an extreme case, with full “up” elevator on the takeoff roll you can bang the tail cone on the ground as you rotate. In demonstration flights this occurs from time to time. No real harm is done (although I feel sort of stupid.) The tail wheel spring mount is a great location for a simple skid (and if you also install a ring then it can be used for a tie-down as well.) A simple, full swivel wheel, (like a desk chair, only larger) that could be plugged into a socket in the tail cone could make the trike version easier to move around while it sits on its tail.
AS A TAIL-DRAGGER: The tail-dragger wing-fold works just fine, however, since the wing is going downhill you are holding the wing back as it folds. I quickly found that the wheels should be chocked so the airplane cannot move during the wing fold. Be ready to hold the wing back as it folds! I never found holding the wing back a problem, (I even did it once in a 30 knot wind) but if it was slippery I would take additional precaution. If much wind is blowing, I found by turning the airplane’s tail toward the wind, the wind pushing against the wing as it folded helped considerably and made it easier yet.
Fuselage/wing attachment alignment: Upon reaching step #30 in systems installation it came to my attention that there was a misalignment differential between the left wing and the right wing. By measuring the angle of attack of one wing and comparing it to the angle of attack of the other wing, we came up with a difference of .6 degrees. After consultation with S/H we determined that the aft cage attachment points for the wings were misplaced by 5/16″ To rectify this situation, we had to modify the aft pivot brackets which fasten the wing to the fuselage. I suggest that you check the angle of attack of both wings and do not assume that the cage lugs are in the proper position as the fuselage may have warped while being constructed.
–Danny – Airlink
Removing the mold wax from fiberglass parts: Lots of different opinions on this one but if you get the mold wax out, there is no reason to sand the gelcoat away. Sanding gelcoat BEFORE getting rid of the wax just pushes the wax on down. The trade secret (not really) to removing any wax is to use mineral spirits and rags or paper towels to “wick” the wax out. Place a soaked towel or rag on the fuselage and then wet it a little more. Wait 10 or 15 minutes then pick the rag up and immediately through it away. Wipe up the area with another soaked rag but never use it again on the shell. It’s a lot easier than sanding and the paint sticks good after fine sanding the gelcoat for adhesion. Mineral Spirits is also hard on the hands and nose. Use the proper precautions.
Three boats done this way without a problem. Similar to cleaning the oil spots from a driveway. Using lacquer thinner or similar solvent, the oil will rise out of the pores in the concrete but as soon as the solvent dries, the oil returns to the pores unless the spot is covered with a rag which will “wick” the oil before it has a chance to return to the concrete. Mineral Spirits seem to work best with wax!
Fuselage distortion: During assembly of a GlaStar here at Arlington, the builder was basically following the manual, having installed the engine and tail feathers, but not the top deck or fuselage struts. The plane was sitting on its tricycle gear. He was beta testing the header tank installation and complained that the tanks wouldn’t fit in the intended space. Upon inspection of his airframe I noted that the fuselage shells had pulled substantially away from the aft wing root (3/8″+) while remaining in contact with the front wing root. With the wings extended, the force necessary to bring the shell out into position was excessive. After scratching my head for a few minutes, I got my back under the tail cone and lifted up about 100-150 lb. This resulted in the shell conforming to the wing root with relatively little force.
What happened? With the aft deck and drag struts yet not installed, the tail feathers and aft fuselage sagged under their own weight, causing the shell in the area of the wing root to move inboard, away from the wing. If you look at the fuselage in this state of completion, you can see why and how this would happen. There is very little structure at the top of the shell to help carry the weight of the tail.
The end result is this: For those of you building tri-gear airplanes and following the manual (i.e. engine installed before the top deck and struts are attached), support the tail with enough force to roughly equal the weight of these components. This will make top deck installation a whole lot easier, too!
Alternately, you may want to consider performing the Infamous “Section X, Step 7” after finishing the top deck installation (steps 129 – 136.1). There is some argument over how much effect the weight of the engine has on the fuselage shell, but either method listed above should give satisfactory results.
If you are building a taildragger, you may have problems with the aft root area being too wide, but the loading condition is far less severe.
–John P. Coussens, SHAI