Long-EZ R1145MS Canard Update
January 1986
IMPORTANT for all builders of the R1145MS canard: if you bought NC-CLT aluminum lift tabs from Ken Brock. These are the "retrofit" lift tabs and should have been used only by builders planning on replacing an existing, already -mounted canard. For some unknown reason, a few builders building this canard as new construction have managed to use this lift tab. It is best recognized by the fact that it was blank at the attach point. It did have 3 holes at the top, exactly as the original CLT lift tab did, but it does not have a hole at the lower, rounded end. If you have used the CLT original lift tab which did have a pilot hole drilled in the rounded end, you are7K.
If you have used the blank lift tab from Brock, Part #NC-CLT, it must be replaced. DO NOT FLY WITH THIS LIFT TAB. This tab was incorrectly manufactured from 2024-0 aluminum which is dead soft. The correct material is 2024-T3 aluminum which is heat treated and much harder, with a much higher bearing load capability. Ken Brock has mailed out registered letters to all known purchasers of part #NC-CLT warning of the incorrect material and offering to replace them with the correct material. Do not iqnore this situation, even if you have installed t-hem -and are ready to fly, ground the airplane until they have been removed and repaired.
This is really not such a traumatic job as it appears! We have done it ourselves several times. Using a Dremel saw, carefully cut through the bottom skin in front of each lift tab (don't try to cut through the spar cap!!). Remove a skin patch approximately 2" wide by 1 3/4" forward of and centered about each lift tab. (See sketch).
Now dig out enough foam to be able to see the heads of the three AN-4 bolts that anchor the NC-CLT lift tabs to the shear web. Using a dull chisel or even a screwdriver and a small hammer, chip away enough micro so that you can fit a 7/16" box-end wrench on each bolt head. Remove these bolts and give the lift tabs a sharp tap forward and they will pop off. Send them back to Brock in exchange for the "real" ones. Sand the aft face of the new lift tabs with 320 grit and sand the face of the shear web. Smear a thin layer of flox onto the shear web and re-install the three AN-4 bolts.
Carve a block of blue foam to fit as closely as possible into each of the holes and micro them into place. (Pour-in-place X-40 can also be used). Sand the foam to match the bottom contour, and carefully sand the bottom skin completely dull a minimum of 3" each side of each hole and about I" forward of each hole. Layup 3 plies of UND spanwise. Across the repair area, the largest ply goes on first. Since most, if not all of this repair is inside the fuselage very little fairing is necessary. Do not be intimidated by this repair, it is quite easy and can be done in a surprisingly short time. We have received several more reports from builders who have completed and flown the R1145MS xanard and without exception, all have reported no rain trim change.
One builder, though, has reported a "flat spot" or area of low response when he pushes the nose down (elevator trailing edge up). He has adequate nose down authority, but has to push forward more than what he feels is normal for good nose down response. We have looked at his canard quite carefully and have not found any obvious difference. We have noticed a slightly "softer" nose down response when compared directly with the original GU canard, but no "flat spot" or area of almost no response. We would appreciate hearing from all builders who are flying the new canard.
Please report your opinion of the flying qualities, control authority, any rotation speed differences, any stall speed difference, and of course behavior in the rain. Comparisons with your original canard would be useful, too. When you build your R1145MS canard, areas to be as accurate as possible with that are sometimes ignored, are the shape of the canard "cove" or trailing edge and the elevator leading edge. These two define the "slot" shape, which is quite critical and should be given your best attention. The lower half of the leading edge of the elevator should be a section of a circle, and smooth. There should be no spanwise bumps or ridges. (see sketch).
ELEVATOR SHAPE
We have had this in many Cps in the past, but surprisingly, we still find builders out there with the bottoms of their elevators convex or curved. No matter which canard you have, you must have perfectly flat bottoms on your elevators. Lay a machinists 6" scale or other known straight edge chordwise across the elevator bottom. There should be contact from the tangent point of the elevator torque tube to the trailing edge as shown in the correct example below.
If your elevators are not flat or look like the INCORRECT example, your elevator will try to float trailing edge down in flight. As a result you will find yourself pushing forward on the stick at cruise speed, and probably will not have enough trim authority to trim off this force. This is normal at very high speeds, but should not be true at cruise speeds.
R1145MS CANARD
Several builders have reported not being able to get the full 15 degrees of elevator trailing edge up travel. This is very important to assure adequate nose down authority at aft limit CG. The best way to assure that this does not happen to you is to follow the plans as far as jigging the elevators into position with the NC-3 hinges inserted into the slots in the canard. Do not pour in the wet flox yet! Using scraps of wood stirring sticks (tongue depressors) and Hot Stuff glue, temporarily tack each NC-3 to the canard bottom skin as shown.
Use Hot Shot to kick the Hot Stuff off. (If you don't have a bottle of the thick Hot Stuff and Hot Shot, you really are missing a very handy jigging tool). You should now have the NC-3 elevator hinges temporarily bonded into position, with the elevators mounted to them. Carefully break off the elevator jigs. This should let you swing the elevators on their pivot pins. Using an angle finder (Sears or Pro-line) check the full available elevator travel.
If you find you are unable to get the full 15' of elevator trailing edge up-travel, break the Hot Stuff glue joints, and repeat the procedure, this time shimming the jigs off the canard bottom skin with pieces of tongue depressors. This will move the elevators down relative to the canard, allowing more travel in the trailing edge up direction (nose down command). Once you have a full 15 degrees or even 16 degrees to allow for finish, re-bondo the jigs to the canard and elevators. Break off the Hot Stuffed scraps and pour in the wet flox to lock the NC-3s in place. Do not pour flox into these slots until you are absolutely confident that you have the full 15 degrees of travel. Removing these NC-3s after the flox cures is virtually impossible.
WELDMENTS FOR THE R1145MS CANARD
Paul Green from Ken Brock Mfg. would like all builders of the new R1145MS canard to know that when Brock made the first run of NC-12A weldments (pitch control belhorn in elevators), the #12 drilled hole called out in the plans, was inadvertently drilled as a #2 hole (almost 1/4" instead of 3/16"). Brock has available a small steel bushing, part #NC12B which can be pressed into this oversize hole and will then give you the correct size #12 hole.
The NC-13 bushing called out on page C-2 is now available from Ken Brock Mfg. Due to a mixup when Paul Green talked to Mike Melvill, Brock has been shipping CS-13 bushings, which are not quite long enough. Several builders have run into this problem, it causes the pivot point at the NC-12A weldments to be too tight. Contact Brock (Paul) for the correct length part #NC-13.
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Judge King, Long-EZ N35OJK has just completed his new R1145MS canard, which he retrofitted to his Long-EZ. He has an easy way to transfer the existing 1/4" diameter holes in the F-22 bulkhead to the aft face of the new undrilled NC-CLT aluminum lift tabs.
1. Fit your new canard per plans, be sure the water Iine is I evel with the top longeron level (correct incidence).
2. Remove the canard and paint a thin film of oil around the hole in the F-22 bulkhead. Spray a coat of any color paint on top of this oil film about 2" diameter around the 1/4" holes.
3. Obtain some foam tape with sticky on both sides (1/8" thick 3M double stick foam tape works great). Stick this on the aft face of the NC-CLT lift tab centered roughly over the area where the hole will be.
4. Install the canard and clamp the NC-CLT I i ft tabs firmly against the F-22. Remove the canard. The paint will now be on the sticky surface of the foam tape and a perfect impression of the 1/4" diameter hole will be clearly visible.
5. Now make a drill guide out of 1 1/2" x 1 112" piece of 1/8" aluminum scrap. Drill a 1/4" diameter hole through it. Lay it on the foam tape, exactly centering the guide hole over the paint impression location of the hole. Clamp this drill guide to the NC-CLT using two small 'C' clamps.
6. Drill through the drill guide, through the foam tape and through the NC-CLT, both left and right and presto! You have a perfectly niatched canard to F-22 bulkhead.