QuickTalk 21 - QUICKIE HINTS
- Category: Q-Talk Articles
- Published: Tuesday, 30 April 1985 07:11
- Written by Jim Masal
- Hits: 2146
My bird, N39JA is Quickie SN 32 but was listed in your Q-2 survey. In many ways it IS more like a Q-2 than a Quickie since I have replaced the Onan with a fully electric, dual ignition 1800cc VW. When I moved the gross up to 800 lbs it was necessary to make the wings stronger but I didn't change them at all. I did add larger wheels to handle the increased weight and to provide braking. The firewall was braced and modified to handle the VW and a new cowl was made to cover it up.
Problems haven't been too bad - about what you'd expect with this sort of mod. Once I dropped it in good and hard on my little farm strip and broke the canard 14 in. out from the fuselage. I determined that the problem was really the result of an inadequate repair made after a close encounter with one of my farm tractors (a story in itself).
I'm not very happy with my VW from Gilbert Duty Custom Aircraft Engines of Sanford, NC, but I don't think it's the basic VW. I'm sure I would have gotten a better engine from HAPI. I'm also sure I would be much happier if I didn't have such a high wing loading. It is a very poor performer in the rain. The first chance I get I am going to fix this with a new set of wings.
Jim Adams N39JA, Rowland, NC
From Jim Masal, Editor
I talked with Swanningson and Hicks who are flying Quickies with the full-length canard vortilons. Consensus is they lower cruise 3-5 mph and substantially reduce touchdown speed. Operation in rain had not yet been tried. Sheehan says this mod is now available for Quickies (May 1) and that he found that the angle of mounting the vortilons on the Quickie had to be changed slightly from that on the Q-2.
From H. L. Shafor #0216
I am not a strong hand propper and my Onan was kicking often. After being hit on the knuckles several times I decided to do something about it (see photo).
A plate was made with pushrod, points and lifting arm mounted. A shallow groove was filed in the crankshaft extension so the added points closed after the regular points and opened after the regular points open. Approximately closed 90 degrees BTC and open at TC. The extra points are wired parallel across the regular points but through a cockpit mounted series switch (as a safety). I have flex wire running to the cockpit. When pushed in, it lifts the pushrod off the shaft and the points are inactive and open. To start: series switch closed, knob pulled out and points are in service. Engine starts after propping then knob is pushed in and switch is open. Timing can be changed by the gap. TC seems best. No more kicks and easy starting.
From Will Hubin
There is a formula from aerodynamics that is of considerable interest for climb-starved Quickie pilots:
Rate of Climb ft/s =
excess power in ft-lbs/s
weight in lbs
Thus a 540 lb Quickie that climbs at 200 ft/min under certain conditions must have excess power (where excess power is defined as the power above that needed to maintain level flight at that same speed) of:
|= (200 ft/min x 1min/60s) (540 lbs)|
|= 1800 ft-lb/s = 3.27 hp|
Under these same conditions, 5 additional horses would yield a climb rate of:
Rate of Climb ft/s =
(3.27hp + 5.0hp)(550ft/lb/s/hp
|8.4 ft/s or 506 ft/min|
Thus only 5 more horses should allow the Quickie to garner much more respect. The problem is that these +5 horses must actually be delivering their energy to the air, i.e. they must be the added hp multiplied by the propeller efficiency. If the prop is only 60% efficient (which the Quickie's may well be, especially if the cylinders have to stick out as on the new engines) then 8.3 horses (5/.6) are needed to yield this 300 ft/min climb rate increase. I suspect the prop efficiency problem explains why the new engines like the Citroen and the Koenig are not doing as much as you might expect for the Quickie's performance.
From Mike Bailey N84MB
The incident occurred last October. My Quickie was flying at 6,500 ft. over Wheeler AFB with no unusual indications on the gauges. In a wings level attitude at 95 mph I heard a deep resonant twang like a heavy spring had just popped. After picking my heart up off the floor, I immediately suspected a ruptured engine mount bolt. Several seconds passed with no unusual changes in vibration (I feel my Onan is reasonably smooth). I began to suspect a failure in the elevator system or perhaps the scrub brakes, but I was just fishing. Nothing unusual ensued. Controls were normal in pitch and roll, power on or off. I concluded I imagined the noise but landed at Dillingham airfield on Oahu as a precaution. The winds were calm and the landing smooth.
After parking, I shook the engine by the prop and nothing seemed amiss. I obviously imagined the whole thing. I chatted with the tower operator for about an hour, then prepared to leave. I tied down the tail and propped the engine but something felt funky this time - sloppy or mushy or something. I pulled the cowling and my heart sank again. Sure enough, the upper left bolt securing the engine to the Kevlar mount had sheared right where it enters the block. The resident A&P helped me fix it. We concluded that the bolt had been subjected to an excessive shear load. There were still 2 threads left on the bolt after the shear point. The bolt had not been threaded far enough into the block even though it had been torqued according to specs. Either the bolt was too short (or the threads were too long) or the bolt had bottomed out in the block hole. Also there were wear facets on the aluminum bushings where they butted against the block.
We installed longer bolts and put washer on each end of the bushing, but I feel the bushings should be replaced with steel. Recessing these new bushings 1/4 to 3/8" into the block to eliminate shear loads at the threads would be a good idea.
When I give full power from idle, the nose tends to pitch down. Looking at the engine mount, it is apparent that the Kevlar is bowed into a slight S curve under the weight of the engine. This will cause the center of thrust to pull down slightly instead of directly along the waterline. Perhaps we need to add washers to the bottom mount bolts or shorten the bushings on the top to compensate?
Generally I am satisfied with the little bird. It does well once airborne but it doesn't come close to the top speed claimed for it - 100 mph is the best I get. She gets airborne at 43-47 mph so I suspect my ASI is inaccurate. The climb is painfully slow and tenuous at full aft stick so I leave the wheels on the tarmac until I hit 70, then I'm sure I'll be flying. I'm a marginal pilot who has had big airfields to work with. I broke one prop in a 15-20 mph crosswind, but I'll take the blame.
Yes, I have a cooling problem too. My 22.5 hp heads have warped (the 20 hp heads are on order). Maybe I haven't been getting full power and that's why speed and climb are marginal. The CHT routinely went up to but not over redline, but I'm not sure I believe it. Besides, I had the thermocouple on the right cylinder and it's the left that gets starved for cooling air.
Can anyone explain to me why I have to trim the nose UP as I go faster? Every other plane I've been in is the other way around.
Many thanks to Sion Silyn Roberts of Auckland for his coaching and suggestions during the final stage of construction. Thanks also to Jim Prell of KS for setting me straight on which heads to buy (part #110-2877 and 110-2878). He also suggested sealing the engine mount bolts with brown Permatex on the inner threads and blue Loctite on the outer threads where they enter the block. I've lost a lot of oil around those threads.
Keep the faith, guys. It really is a lot of fun to fly, but long wide runways are a first flight must for most of us. The trim system takes a little tinkering with no tune properly and an out of tune system can mean HEAVY stick forces which would be extremely unsettling on first flight for a low time pilot.
From Harold Little
To enhance Onan performance I have a builder semi-hint (semi-hint because I don't have a simple method to implement the needed action). To ensure the lowest possible vibration, the flywheel should be balanced accurately. When QAC removes the cooling blower fins from the flywheel, they have also removed the work done by Onan to balance the flywheel, which is the largest rotating mass, greater than all the other components combined, which is the reason that it is the flywheel and also the reason that, when balanced, it will do nearly as much toward smoothing out the engine vibration as does balancing and tracking the prop.
The problem, however, is that the flywheel mounts on a tapered shaft, requiring a tapered mandrel for balancing. With such a mandrel, the balancing is performed as readily as balancing the prop. But where to get the mandrel except to have a machine shop turn one and balance the flywheel while they're at it?
And this is a significant problem, for just a slight amount of unbalance in the massive flywheel will destroy the best engine mounting/prop balancing installation. Many builders have done everything recommended by both QAC and QBA to no avail, while other, performing the same operations, have great success because, unknowingly, the flywheels are balanced, or nearly so.
A solution to this sticky problem will be another significant step in the enhancement of the utility of the ubiquitous Onan.
GOOD NEWS: BAD NEWS
May a thousand flatulent camels circle my campsite nervously!!! This one-man show bizniz has resulted in misfiling some good info submitted up to a year ago (about the time Robert turned it all over to me). A thousand pardons to you miffed (no doubt) contributors. I'll start packin' it in QUICKTALK as of this issue - Jim.
From Larry Weishaar and Jim Doyle #2391
7-16-83: This is an interim report on our efforts to whomp up our own NASA LA(1) 0417MOD canard airfoil (mentioned in QUICKTALK #9). Neither my partner, Jim Doyle, nor I are aerodynamicists, but we both have technical backgrounds and I have an engineering license in IL. We are reasonably confident we can build this canard - in fact we're betting our butts on it, but wouldn't want to bet anyone else's.
Our first step was to get a sample of carbon fiber and lay up some test pieces. These were 10 layers thick, about .082". We had tension specimens prepared and tested by a local lab, but their machinery was not capable of clamping the sample sufficiently to fail a 1/2" wide test section. However, they were able to develop stress/strain curves to about 50,000 psi, which showed a minimum modulus of elasticity of 26.6 million psi - only about 10% less than steel. The stuff is amazingly stiff and only weighs 18% as much as steel. We loaded a 1/2" x .082" "beam" and it busted at a calculated stress of 185,000 psi, presumably by compression failure, since the literature says it's stronger in tension than compression. This is pretty scant data to base a design on as far as stress is concerned, but with the landing gear loads out at the ends of the canard, the design has to be based on acceptable flexure rather than stress anyway, and we're real confident of the 26 million+ psi "E" value, which controls flexure.
We were able to get NASA Report TP1919 from our state library on microfiche. It has complete lofting data on the airfoil and after about 6 jillion calculations we had all the coordinates to the nearest 1/64th inch. A real eye-strainer. but lo and behol', it looks just like it's supposed to. We used the same proportions as the original canard to locate the elevator hinge line. Here we departed from the "normal" shape and made the elevators 10% thicker than the theoretical airfoil. This came from an item by Jim Bede in the Mar. '71 SPORT AVIATION indicating that this thickening actually reduces drag at the juncture between the elevator and main surface for some arcane reason. We used the same washout (1.67 degrees) between BL-15 and BL-100 as measured from the Q-2 plans and plan to use the same angle of incidence.
Our calculations for the spar [built somewhat like the spar box in the Dragonfly - ED.] translates into the equivalent of about a 15" drop test or just flying into the ground at a descent rate of maybe 400 fpm. This bugger may actually be too stiff for a comfortable ground ride!
We've bought $240 worth of carbon fiber from Wicks and will have plenty left to make an engine mount we're also designing. The rest of the material requirements are WELL within the amounts furnished in the Q-2 kit, and the hardware will be virtually identical.
[Weishaar let us print his method of hard-edging a wood prop in an earlier QUICKTALK which I have personally used with great success - ED.]
From Bill Van Sice #1117 & Gary Goodrich #2257, 4600 Oakdale St., Union City, CA 94587
As a potential retrofit for the old canard to the rainproof version, we are working on a glove-over for the GU airfoil (see photo). Extra facts: 1 extra billet of foam needed; 15 lb weight increase; 10% increase in canard area; we have spent less than $250 in materials; the canard must be off the aircraft and in "D" spar state. Flight testing is about a year off [about now, as we got this letter a year ago - ED] and we'll release all details after this is done. If there are any builders interested in purchasing plans for this retrofit, please send a SASE and we'll respond after testing.
Our mainwing complete less 1 aileron actuator weighs 45 lbs and the canard complete with wheels, brakes and pants but without center linkage is 98 lbs.
From Jack Dempsey #2802
A Q-200 tip: the instructions tell you to hold the carbon spar in place with rubber bands. I cut up an old inner tube which one can get free from most tire repair shops. Cut strips 3/4" wide (so it won't cut into the foam) and 30" long and tie a shoestring bow so you can remove it and use it again.
From Cal Bowens #209
3-5-84: Haven't flown much due to blowing out at least 7 head gaskets - always in the air, of course.
I am switching landing gear to conventional. I'm going to use the gear from a Mirage ultralight - 1/2 of their float gear so it's wider than normal (70") with double tube and gusset plates for securing wheel and axle. A real slick and lightweight unit. I equipped it with a 5" Azusa wheel and cable hand brake system. I won't need 15' taxiways anymore or have to get out and lift the plane over pebbles. (Can we see a picture, Cal?)
Over the years I've had to put washers under the bottom engine mount to tip the engine up-thrust. The mount must fatigue with the weight out front over a period of time. The climbout difference is like day and night!
The Phillips head bolt securing the tailwheel steering plate came out making landing a real joy with no steering. I since switched t a safety-wired bolt. The newer ones of course now come welded.
From Richard Kautz #2850
4-8-84: Received my Q-2 package 2 today and found to my surprise a USED altimeter and airspeed indicator. The altimeter was overhauled by a CA firm 2 mo. ago yet it doesn't even work. The pointer doesn't always move and it won't read within 100' when set to the same barometric pressure. It has been my understanding that everything I purchased would be NEW. I haven't found anything in the Sales Agreement to the contrary.
From John Derr #2562
4-14-84: I am building my Q-2 for a Rotorway RW-100 engine and would like to contact others doing likewise. (John sent us a procedure for removing the canard anhedral in preparation for installing Swing's tri gear to be used in an upcoming issue).
From Mike Conlin N60JW
3-28-84: I'm PROUD to say that 60JW actually performs like a real airplane now. I can actually get to pattern altitude before turning downwind (the first time). I changed the heads and gaskets per Harold Little's article and made similar changes to baffling. Engine now runs at 300 degrees CHT DURING climbout, oil temp about 175-200 degrees. I'm not sure why it performs so differently since the only change was heads and baffling. I have the same Cowley 42x30 but the engine will easily run 4000 rpm - checked this with 2 different tachs.
From Bill Mueller #2758
4-12-84: Question: What sort of protective coating can be put on the Q/Q-2 metal parts such as hinge pins, torque tubes, reducers etc. of the elevators and ailerons. Couldn't removal of these pieces be difficult due to corrosion between the parts? No mention is made in the plans for lubrication of these parts.
From Karl Prell
We got a HOT letter from Karl after his Quickie had a bad experience in the rain. It concluded with this P.S. "the chain saw wasn't 'safe' either, but it soon made the Quickie that way (along with a match!).
From Ron Cross #2397
2-14-83: If you plan to use a glass-to-glass bond on the trailing edge of the elevators (see QAC #21) don't hotwire the joggle too deep or you'll get a high spot on the top of the elevator. If you don't hotwire deep enough, you can always micro fill.
Aligning the elevator cores in the jigging templates is the pits. Run 1/4" x 1-1/2" wood stringers between the templates, or else just lay the cores on a level table and use shims to achieve the proper twist.
The lines and edges on the elevator installation and alignment templates are NOT level lines. They are the airfoil chord lines. Also, it appears that the templates do not take into account the thickness of the glass layups so you may want to cut them slightly larger.
Leaving the front of the elevator on the core and inserting the tube is the best way to go, since the tube aligns the cores, but I worried about getting the micro into the foam by just rotating the tube so I used the following method.
Take a solid rubber ball at least 1-1/8" in diameter, cut in half, and run a string through the centers with the rounded sides pointing in the same direction. Use a stirring stick to fill one end of the elevator tube cutout with micro. Now pull the rubber ball halves slowly through the core. Squeeze on the core if necessary. Repeat in the other direction. Inspect your work through the slot in the core.
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