Q-talk 14 - Q-2 TIPS
- Category: Q-Talk Articles
- Published: Tuesday, 28 February 1989 06:11
- Written by Jim Masal
- Hits: 925
From Ted Eiben, Downsville, NY
CG measurements from my plane, N218E, are as follows:
Moment (inch lbs)
Calculations with gas, people, etc. show CG remaining inside the envelope. We have relatively full instrumentation.
1. An X-acto thin blade saw #039 works well in making thin straight cuts where needed for cut-outs, etc.
2. A 5"x9" inspection panel cutout made about 5" behind the firewall on each side of the fuselage helps immensely when working between the instrument panel and the firewall. I mounted the NASA vents on these panels while they were out on the workbench - nice, easy work for a change. (ED. - you can see this idea applied in our previous photos of Bob McFarland's Q-2).
3. I wasn't satisfied with the clearance between #4 exhaust elbows and the lower cowl on my Revmaster. I cut slots in the cowl to clear the exhaust and built up streamline bubbles to cover. Thought of putting a small "bump" on each bubble to give the plane a gender, but decided this would lead to too many questions.
(ED. NOTE: nice streamline bubbles can be had by laying glass over a teaspoon or tablespoon, etc.)
Time for my progress report.
Both the building and the delivery times are beginning to test my stick-to-it-iveness and patience. As of today (11/11/88), I am into the 415th day of the 30-day delivery period, money upfront, and the Q200 firewall forward kit from Customs Composite Components, Inc. is still incomplete. A part of the kit was shipped from Aircraft Spruce & Specialty Company (2 parcels from 2 different locations). Someone at AS&S entered my address incorrectly into their micro and I found out about it the hard way. The larger parcel was never delivered.
The undelivered parcel was classified as lost, which, unfortunately, involved the US and Canadian Post Office stilted bureaucracy trying to sort out the insurance claim. This is where the real fun began. My letter file eventually grew over one inch thick, not mentioning the phone calls and the afternoons taken off from work to deal with the Post Office in person. After a few of my visits I was declared a persona non grata and barred from ever entering the building again (the customs are in the same building and they know me pretty well too). Interestingly, but not surprisingly, just mentioning you and the Q-TALK in my letter to AS&S resulted in an instant reply from Jim Irwin where there was no response before! (See copy).
My advice to the average potential 500 hours Q-plane builder today would be: 'Forget it brother! Hang onto your money and run so fast that you start passing anabolic steroids' - and if he still would not be convinced, I would give him to read the letter by R. D. Hess in Quicktalk #18, p. 5.
Back in '83 I did not have (and stupidly did not even seek) the luxury of such sage advice. Enthusiasm is like running wild in pitch dark - one may get to the destination but one may just as well hit something along the way. And in my case it was enthusiasm run amuck. Perfect plane! How come the sky is not white with them?
Most of us have had our fair share of these hits: we have bumps, bruises, burned holes in our pockets and broken dreams...not to mention the airplanes and the dead pilots...to prove it. And yet, amazingly, there are some who have succeeded. I have the deepest respect for those blessed few mavericks who came out on top and somehow crafted safe and reliable machines.
Enough of philosophizing, let's talk about my building progress now:
*0200 magneto box done.
*Header tank completed. Yes, there is enough room to make it at least as large as the original Q2 tank (see photos). It is a little tricky and in situ assembling/fitting is a must. The two access cavities, which are near the firewall, make room for the removal of the two upper AN6-72 engine mount bolts. Fuel lines were upgraded to 3/8" and there is a drainage plus to facilitate the removal of any accumulated crap (added after the photos were taken).
*Three additional tapered UNI spar caps were laminated on both the top and the bottom of the main wing standard layup to eliminate the Waddelow spots and to end the controversy. It may be 2 lbs heavier but I will happily slim down 3 lbs instead and enjoy a worry-free sleep.
*The main wing top surface was finished while the wing was still on the jig table (1 month of spare time).
*A 7" rudder extension was machined to increase the rudder area by 26%. The trailing edge height was shortened to 3".
Next on my list are the floating caliper brakes - although they are 2 classes above the original LeGare toe brakes, I have never quite liked their slipshod installation given in the QAC plans. The project is also slowly outgrowing its present 16x22 ft garage location and the time has come to move it for the finicky final assembly. There is a problem!
Needless to say, Jim, Q-Talk keeps my somewhat faltering spirits up and I am therefore enclosing my '89 dues - probably the best investment I can make in the new year. Many Q-Talk contributions are excellent.
Thanks for keeping the flame burning, Jim.
Igor Mokrys, Calgary
Annual Progress Report: Airframe Structure: Complete, Q200 is sitting on Tri-Q Gear. Wing and canard on and aligned. Amazing the psychological difference wingtips made. If your wing or canard is in the airplane, but tip-less, PUT TIPS ON IT. You'll feel better, and for only an hour's work. Tail attachment complete, in fact, tail cone & fin/rudder ready to paint. Engine Compartment: 0-200 in mounts, cowling installed. Reworked mag box to use stock Continental alternator. Engine needs all hookups, wiring, baffling, exhaust, etc. (all on hand, just takes time). Interior: Main and Header tanks installed. Canopy forward hinged and all latches functional. Rudder pedal mounts in (both sides). Seat belt attach points done. Center seat belt done as per plans, but first we put down two additional plies BID about 10 x 10", so the .75" overlap onto the 'floor' called for in the plans would get a better grip (wet bond vs. mechanical bond). Outboard seat belt attach done as shown in earlier QBA letters, I.E. 1/8 aluminum plate recessed in from outside; 3 layers BID inside, about 7 x 7", 6 x 6", etc. 4 layers outside, similar scale. Looks strong as hell, maybe an oz. or two heavier than plans version. This, a Waddelow canard, and an oversize canopy, are about the only real divergence from plans (Q200 & TRI-Q) anywhere in the airplane. Systems: Wingtip light wires sitting in wings, antennas built in structure. Ailerons done to inboard pivots. Lot of work here.
Anybody out there running dual throttles (that you like)? Anybody running dual rudder pedals WITHOUT a torque tube? (One set of pedals for a 6'6" pilot, one set for a 5'9" one...they aren't at same FS!) Anybody running dual brakes on a TRI-Q? Please call me; we intend to make all three of those work. How about some photos or diagrams of electric pitch trim? We want to make this work too (no crossing hands on final). By the way, the phrase "trim runaway" scares us, does it scare you? How about a big toggle, by the trim wheel, that severs the juice to the trim motor?
Our contributions to the Hint file:
To get a good gas tank seal, you should paint an extra coat of pure epoxy over the fuselage inside the tank (sand first). For the best seal, flox & tape the tank in place while this is still wet. The plans built float gauge would stick to this...We used a string, run in through the 5/8 fuel return pipe, under the float, to a piece of gray tape. This held the float in the full up position, out of harm's (and gooey's) way. After everything cured, a gentle pull on the string popped the tape, which was sized to come out through the pipe. Practice with tank on the bench first.
To reduce the possibility of gas reaching foam (even white foam), we took a wire brush in a drill to the exposed edges of the tank and baffles. This removes about 3/16" of foam quite easily. We then trowel flox in place of the foam, just prior to installing the tank.
I was ready to tear my hair out trying to get my cowling aligned, using the plans built flange. Quickie's photos imply the cowling fits against the flange so well you can use clecos for temporary alignment. This is a real pain.
A Vari-EZ friend dropped by and suggested we move the cowling flange back/in about 3/16 to 1/4", and LEAVE THIS GAP to allow adjustments. When everything fits, use flox/micro to fill in.
We cut/sanded the original flange off (it was bonded on, not riveted). We then took 1" of the rear portion of the cowl that was trimmed off during fitting, and made a new flange on the firewall. It was spaced in about 1/4" from the skin, and held in place with small dabs of Bondo and/or 5-Minute. Two layers of BID completed the new flange. We placed foam weather-strip on the flange and draped the cowl over it. Then, we drilled for cowl screws in pairs, working from the top center out. After drilling a pair, remove the cowl and set the nutplates. Then reinstall the cowl, tightening the screws enough to compress the weather-strip and align the cowl at each section. Then do the next pair. When all screws are in, use flox/micro at rear edge to fair any remaining gaps (gray tape on cowl). This also establishes a 'ledge' for the cowl to tighten against, so you don't have to judge each screw each time.
Did the upper half first, then lower, then joined at seams. Result: Cowling finished in three days, and I still have some hair left.
Speaking of cowlings, I couldn't figure out a way to squeeze or hammer the rivets for the nut plates, without damaging the fiberglass. I have no trouble riveting parts that will go on my bench, but the cowl flange had me stumped. I substituted #2 countersunk screws and nuts, with a dab of paint to lock the nut against vibration. Much easier.
When we built antennas in the wing, we left enough coax to run all the way to the instrument panel with no connectors. Same deal on the rudder com antenna, but just enough to go up to the tail separation point. Easy to do, and coax connectors in vibrating airplanes are a nuisance.
Danal Estes #2872
Patricia J. Wright
From Alan McFarland
Note, I have about 10 hours and 30 landings on the system I describe below. It works fine, though I am still not completely happy as the adjustment is touchy, and it still vibrates a bit when I pull the plane backwards. Q-TALK Sept/Oct 1988 sounds like it also has a solution. And Scott Swing tells me that he hears only good things from people who "float" their disks. The only certainly... the system as designed is the pits.
I have learned that the brake calipers twist in various directions, allowed by the "floating" attachment. After 10 hours, this is so bad that if I back the plane up, the brakes bind. This isn't so likely to happen going forward as it has got to do with gravity, but with just the right bump, it could. I had about 1/4" of "float" built into the spacer, which is about the thickness of the pad and I assume what the plans called for.
For the purpose of this discussion, I'll consider the left caliper pointing forward and twisting with pitch, roll, and yaw. When the brake is off, as the caliper vibrates, gravity "rolls" it counter-clockwise. When the brake is applied, it then jerks back into alignment, causing a less than smooth transition into braking. If the wheel is backed up, it grabs without even applying the brakes.
My solution was to put a floating joint on all four attach points of the aluminum attach plate, BUT to make the spacer for each of these joints so short as to only allow a hinging movement (say 1/32" more than the plate width). As a result the "roll" is all but eliminated. In neither system does the caliper "pitch", and the "yaw" which could happen in either system is not a problem.
To do the changeover, 1) two of the holes in the attach plate need to be enlarged to hold the new spacers; 2) the new spacers are made; and 3) the old spacers are shortened. I would then install the wheel with the outboard axle spacer removed. This will allow the wheel to be moved outward to simulate wear on the pad, and thereby guaranteeing the full travel of the caliper. You may notice that tightening the four bolts tends to bind the float mechanisms. I tighten them with the joints held in an extreme position, and it seems to keep them centered.
If you have the tools and tubing, the change should only take a few hours, plus the time it takes you to convince yourself of the soundness of the idea or to discover a better one (maybe days!). I was trying to find a solution that didn't require me to remake the aluminum plates.
I started on this from an idea in Jan/Feb 87 Q-TALK on page 8 by Mike Peay. Please refer to it, too! He is right that there is torque in the old system, which is also in my system. However I do not have the slop of the old system. I assume his will work if his two floating spacers are kept short as I suggest; however, two things haunted me as I tried to install it. First, gravity (see above) would tend to cause his system to bind while the plane is going forward (not backwards as before), as the left caliper would now want to "roll" clockwise instead of counter-clockwise. Second, I could not see how to easily attach the aluminum to the caliper without it protruding out where it would contact the disk as the pad wore.
OTHER THOUGHTS AND TIPS
My plane weighs in at 640 lbs. I was a bit surprised at first as I had been very careful in many ways not to get a heavy plane (the epoxy was well squeegeed and blotted, and the paint was used sparingly). However I do have a Bendix mags (larger than Slick), standard starter, standard generator, large tires, and big battery (25 amp hour, 25 pound). The battery is mounted behind the first bulkhead in the tail, and is just right for a center of the envelope CG. Gene says that the rear of the envelope is where pitch becomes unstable (I notice this when adjusting the reflex), and that the front of the envelope is where there is not enough flare authority on landing.
The pull starter as outlined by me in the Jan/Feb 87 Q-TALK on page 8 works great!!!
A reflexor is a must for first flights, in my opinion. Mine is set at 1/4" aileron up, which forces the tail down. At neutral the plane is much more squirrelly. Landings currently are definitely tail first. I notice with zero reflex and 30 pounds of luggage that the pitch become noticeably unstable, though it is not unstable at 1/4" up (this I haven't understood yet). By the way, as noted in the Jan/Feb 87 Q-TALK, I did reverse the sense of my reflexor control. This cannot, however, be done without changing the cable (I did it by modifying the end), as a cable cannot be expected to push what gravity in this case is resisting. The throttle cable, for example, will push and pull.
Gas lines were changed from 1/4" to 3/8" from the header forward (ala Scott Swing). Now the flow with a full header is 20 gal/hour. Before the flow was 12 gal/hour or just what Continental said the max fuel flow of the engine was. I replaced all poly-flow line that attached to those soft aluminum tubes, with rubber auto fuel line (Gene now says it's his choice). To tighten poly-flow tight enough to stop leaks (I had a lot), required so much pressure that I popped clamps and crushed tubes. Gas smell has been my single most annoying problem. I would not even think of filling tanks until these changeovers are done. I use two clamps for safety and effectiveness over the aluminum. Finally (ala Scott), the line running from ram air into the header tank MUST run continuously uphill. If not, gas (somehow from pressure or condensation, and I have seen it) may accumulate in the "sump", and keep the tank from breathing. It could stop the engine.
See-thru fuel filters are assembled by first tightening the screen and then tightening the glass. I checked it at about the six-hour point, and little particles from the white foam had about clogged its input. I will check it often for awhile, though it does not seem to be accumulating so fast again.
Gas and vapor leaks can be found in the following way. Inflate and tape a large balloon to the ram air inlet to pressurize the tanks (I noted earlier that hooking the balloon to the Pitot tube registered 140 mph). Then take a piece of 3/8 poly-flow tube about two feet long, and insert one end in your nose and the other near the suspected leak (no one has ever seen me do this). It takes a bit of patience, but works well. I also discovered that my fresh air inlet is JUST downwind of my fuel filler door. I know this became fuel stains from spills trace neat little curves along the fuselage that are 30 degrees down and back from the filler door. The "bottle cap" leaks vapors. I've temporarily fixed it with Teflon tape. What a headache.
Brake bleeding can be done by one person by using the parking brake. Set it, pump the system up, release fluid from the caliper via a tube into a cup, and repeat a number of times patiently. Also as you pump, let the air flow back up into the reservoir. And don't pump it dry. And keep the cap on the reservoir while pumping, otherwise it will squirt.
The brake calipers leaked for me originally. I had to replace the seals, which had sat on the shelf too long (replaced one then had to do the second shortly thereafter). The kit is #30059005 for a 150 x 1 caliper disc brake (mineral fluid). Airheart Brake Company, 1028 S. Third St., Minneapolis, MN 55415, (612) 333-0707. Expect a run-a-round. Most dealers they referred me to did not have the part. However, I think there is a new "dealer" from the factory at Airheart Brake Co., 1440 W. Huston Ave #7, Gilbert, AZ 85234, (602) 892-7892 who specializes in our kind of stuff. Also "soft" pads are #30059000 and "hard" pads are #30059006. I've heard that our original pads were "soft", and that "hard" pads brake almost as well and last longer.
Wheel rub was noticed as black marks on the inside of the wheel pants after some tight turns during taxi testing. I changed the axle spacer size and brake spacer washers, thereby moving the wheel over a bit. It is a good thing to check.
Angles, ala Scott Swing, gave me confidence before my first flight. First buy a Sears Universal Protractor ($17). It is a level that measures angles referenced to gravity. Define a "forward" and note the difference between measurements made "forward" and "backward". Once understood, it will measure +/- 1/2 a degree. The ground angle measurement that most of you are familiar with is taken by setting the protractor on the fuselage, just forward of the canopy. It should read no more than one-degree nose up. Next read the left canard just forward of the elevator as inboard as possible, and then the main wing inboard just forward of the aileron. A plans-built Q-200 should have a one-degree higher angle of attack for the canard than the main wing, which turns out to be this difference. Scott says that zero degrees seems OK, too. He never made the measurement on the old canard. I know of one plane that flies well, about two degrees off from this (but I don't remember which direction). Again a reflexor could be essential. Comparing left to right is good, too (but don't scare yourself because you've turned the protractor around). This tool is good for many things!
A push-to-test switch and light pushed up before takeoff guarantees me that the canopy is latched, the fuel pump is on, the carb heat is off, the mixture is rich, and the parking brake is off. Similarly before landing, pushing the same switch down, checks all the same things, except the carb heat must now be on. It's the final thing I do after completing my regular checklist. It is all done with micro switches, and should they fail, I just check again more carefully.
Cooling originally was not great. Oil temp ran around 220 (basically red-line), and CHT around 350 (OK). This was in the spring, either in the pattern or after a climb. Nothing much except a long descent cooled it off. Again, ala Scott, I bought and added the piece of baffle that runs under the belly of the engine (above the carburetor) on a Cessna 150 ($20 used). That belly is where the oil drains on the way back to the sump. Now in the fall (same outside temps), oil temp is 180 - 190, and CHT is about the same. Do not believe anyone who tells you that this baffle is not necessary. I'm sure glad I was not test flying in the summer. You must take off a couple of intake manifold tubes to install the baffle. I then cut my front baffle (the one that runs across the front of the engine), so that I could bend the center portion of it down to meet and feed into the new baffle. Not a big deal after a lot of 3D head scratching. I'll send you tracings of the Cessna parts and a few notes, if you send me $2. Alan McFarland, W. 1821 11th, Spokane, WA 99204, (509) 747-7250.
Landings are where the excitement is! The stall is 68 mph indicated. I try to come in 100 on approach, 90 over threshold, and then hold it off as long as possible. If I'm hot, the landings are easiest, but the plane squirrels down the runway for a while as it is still flying. If I'm slow on approach, then the nose is so high that I misjudge my height and bounce. I prefer the former, though I'm looking for a compromise. I tend to use 3000 - 4000 feet of runway. Low, long passes are still excellent practice. One hint, do stop-and-goes, NOT touch-and-goes! The torque comes as an unwelcome surprise that a beginner just does not need. This beginner did not even like full power takeoffs for a while.
Cross winds (I'm on a roll, as Duane Swing once said) are not for me yet; however, I have a thought. Rather than aileron steering as such, how about just holding the amount of aileron necessary to correct during the approach. For example, if the cross wind is from the left, then the stick will be to the left on approach already, so just hold it there on rollout. It would be in the right direction to help counter the weather vane effect, but would not require great dexterity (I once crossed my hands on the handle bars for fun, and landed on my nose). Someone with cross wind experience, please comment on this in Q-TALK.
Finally, I have nothing but good things to say about David at Terra who started my warranty on the day my plane was signed off for its first flight. This was 3 years after I bought it. Since, they have sent me a loaner to determine whether a problem is in my radio or my antennae. Thanks!
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