Long-EZ Builder Hints
October 1980
Wing Jig Templates - Clarification - after gluing the ‘A’ drawing together, connect the W.L.‘s with a straight edge. This will make it a lot easier to get things straight, and will be a check that the drawings don’t warp when glued down. When Dick and Mike built their Long-EZ wings, the jigs fit the foam cores well except at the leading edges, where a gap of 0.1’ and 0.4" was apparent between jigs and foam cores. A few builders have found this as well, and a few have reported that theirs fitted tight. The jigs are sized to be a bit loose to avoid interference with the foam core and possibly there is some paper stretch or shrinkage during gluing. If you have a gap, it is not a problem. Go ahead and align the foam cores using the trailing edge as a reference, (butt core T.E. to jigs) and center the leading edges of the foam cores in the jigs, accepting the gap as shown.
Wing Spar Caps - We have found a good way to clamp the spar caps during cure to get minimal waviness and to force them down level with the wing cores. See the accompanying sketch. Select some hot wire cuts of Styrofoam (left over from wing core cutting) about 1" to 1-1/2" thick and cut them 4" wide. These should be covered on one side with gray duct tape for a release, and you should cut and fit them end to end to go the length of the spar cap. Get these prepared before doing the cap lay-up. Now lay-up the cap normally, squeegee it out properly, then carefully place the foam pieces (with duct tape down) on top of the wet cap. Weight the foam down evenly with lead shot bags, milk jugs full of sand, salt bags or whatever. This will pack the cap lay-up down evenly and result in less sanding before the skin lay-up.
Canopy - page 18-2. Do not compromise the "A" dimension, this 13-1/2" is required for good forward visibility. If it is desirable to lower the aft end of the canopy to better fair it into the cowling, or to meet the "B" dimension, it is structurally ok to remove the flange the Plexiglas aft of the roll over structure.
When you get your canopy, do check a couple of dimensions: measure from the point of the Plexiglas nose, aft 27". Now squeeze the sides in at this 27" point, ‘til it measures 18.5", hold a straight edge across at this point, and measure up to the inside top of the canopy. For it to fit a Long-EZ satisfactorily this dimension should be from 11.25" to 12.75". If it is less than 11.25" it will reduce forward visibility by forcing the pilots head too low.
Wing Attachment — Follow the instructions on page 19-18, step 1, except drill the 1/4" holes through the forward face and the aft face of the center-section spar. Now follow through step 2 and use two sawhorses/boxes per wing, with blocks of foam left over from the wing to bring the wings up close to the height of the center-section spar. Now cut 4 foam wedges 7" wide, 2" thick tapering to nothing. These are used to fine tune the height of the wing at the center-section spar and the tip. Now get a suitcase strap, rope or several belts and strap the inboard wing to the center-section spar.
This stabilizes the wing against the center-section spar, and stops It from moving fore and aft and in sweep while you adjust the tip and root for correct relationship to the spar. Cinch the straps tight, double check that the wings fit well to the center-section and especially important that the incidence is correct (of course, the fuselage must be level). Four large ‘blobs’ of Bondo about (3/4" die) are placed roughly above and below the hard point. Allow this Bondo to cure completely, before you attempt to drill the 6 mounting holes. Now, run your long 1/2" drill through the center-section spar and drill through the "hard points" in the wings.
You are now ready to enlarge all six holes to 5/8" die., using your spotface tool. As you drill into each "hard point" the 5/8" spot face will break through each lamination of glass and aluminum. You will find that the spot face will break loose a thin "washer" of glass or aluminum located on its cutting edges each time it breaks through a layer. At this point it can no longer cut, and you must withdraw the tool and remove the small "washer" or "disc". Do not try to drill all the way through one hole in one operation. Clear the spotface often, and every time it breaks through a layer of glass or aluminum. It is good idea to move from one hole to another to allow each hole to cool off.
You must not get the wing fitting area hot, go slowly and carefully, clearing often, and if necessary, stop and allow things to cool. We have found that this entire set up, jigging and drilling both wings to the center-section, takes about 5 hours, 2 hours just for drilling. If you are building your Long-EZ in a 2 car garage, you will have to take it outside to do this set up. Be sure to protect the fuselage and wings from direct sunlight with white bed sheets or newspapers. We found that our spotface tool tended to bore a hole as much as .007" over its intended .625" size. This results in a loose fit on the LWA9 bushings. It is satisfactory to fill this void with wet flox when installing the bushings. It is recommended that this flox be cured while the wing is bolted to the center-section spar. This assures perfect alignment of the bolt holes.
Finishing — CAUTION! Do not ever wipe paint thinners on any part of your structure. Minute pin holes in the epoxy/glass skin can allow the thinners to penetrate down to the Styrofoam, which dissolves in thinners. This can cause the skin to de-bond from the core. For the same reason, care should be taken to fill any possibly dry areas (presence of air voids) or areas with pin holes, with epoxy, before applying featherfill or primer, both of which contain solvents that can attack the Styrofoam. Epoxy wiped onto the surface with a rag should be sufficient to seal lay-ups that otherwise maybe dry enough to allow thinners or primers to penetrate. The surface must be sanded after epoxy cure.
A builder has suggested using left over scraps of R45 (dark blue) foam in the landing gear attachment area where we call out using urethane foam. This is fine, although not as easy to carve down to the wood longerons as the urethane.
Ailerons — use care on the leading edges of aileron to get the full radius around the mass balance without a sharp edge. A sharp edge will cause early airflow separation on the up-deflected aileron and will reduce roll power. See sketches.
Landing Brake Installation — Page 24-1, the sketch showing LC1, does not show the cutout necessary for seat belt clearance. Before bonding LC1 into place, make the cut out per the right side.
Speed Brake Rigging — Due to the fuselage bottom on the Long being thinner than the VariEze, you may have to shorten the LB21 push-rod (turn a few more threads on it with a die). When rigging the speed brake, be sure to obtain the correct amount of offset with the brake in the down position. The top rod end must be 0.4" aft of a straight line drawn between the upper and lower pivots. It is acceptable to vary the 0.4 dimension �..1 as required to obtain the 40 lb. brake closing force.
LONG-EZ Com Antenna - At last, a high performance com antenna. Jim Weir from Radio Systems Technology developed a com antenna for the Long-EZ that fits in the winglet. (see photo) We have tested it in the Long-EZ N79RA and found It to have excellent range. We were able to use it at distances of over 80 nm. The antenna uses copper foil and RG58U lead in. It does not require a ground plane.
It can be installed on the foam core before glassing and is completely enclosed within the winglet. Ours was placed on the outside skin after drilling some carefully-aimed holes. Install the antenna system before glassing the inboard side of the winglet. Cut 2 strips of copper toil 20.3" long, remove the protective backing and stick the foil to the foam one inch from, and parallel to, the trailing edge.
Measure the rudder cut out area and bend the lower (2") end of the foil forward to miss the rudder. From where the two foil strips come together cut a slot just deep enough to hold the RG-58U/A lead in cable flush with the foam surface. Hold the lead in with tooth picks similar to the method used on page 19-7 rudder conduit. Be sure the three Ferrite Baluns are installed just above the connection as shown.
Solder the center wire of the RG-58U/A to the top foil strip and the outside "ground" braid to the lower foil strip. Be sure the upper and lower foil strips don’t touch or short out. Use about 1/8" separation. Check that none of the wire, ferrite baluns, etc. stick up above the foam surface, trowel in dry micro around the solder joints and other voids and glass the inboard winglet as per the plans. Coil up the excess cable and thread it through the wing during winglet-installation.
The antenna kit is available from:
Radio Systems Technology
Grass Valley Ave.
Grass Valley, Ca 95945
Antenna kit price -
Assembled — $25.50
(with BNC connectors)
Unassembled - $15.00