Q-talk 74 - LETTERS, ETC.
- Category: Q-Talk Articles
- Published: Sunday, 28 February 1999 06:11
- Written by Tom Moore
- Hits: 3547
QUICKIE FLY/DRIVE IN - May 8th
Q/DF Bull Session/Fly-in, May 8, 1999 at Flying Cloud (FCM) (southwest side of Minneapolis). My hangar is on the north side of the airport on Charlie Lane (the tower can direct you to Charlie). We plan on having hamburgers and brats around noon. There will be plenty to eat and drink. I will be showing/running my Q-Baru for all to see and critique. The Playboy centerfold Bunny's from Jan, Feb, Mar & Apr 1999 will be there as will be the Baywatch Girls (they constantly hang out at my hangar. I just can't get rid of them.) Call or email if you intend to come or need more info.
AIRHEART PERFORMANCE PRODUCTS
NEW telephone number -- 602-449-3660
If you're looking for replacement parts for your original brakes on the Q write down this new number.
Tom and Fellow QBAers,
With the arrival of the New Year, and the promise of many first flight reports from many among us this year, I too have some good progress to report on my Q-1. My prototype LS(1) canard is now completed! Yippee!!!! I believe I reported earlier that I laminated in the Graphlite rod pack on the upper surface and having learned how this stuff behaves from doing the lower surface, this was a cakewalk. Anyway, progress on completing it came along real fast last month. Our Chapter Technical Counselor and I managed to take advantage of some unusually warm weather (actually great epoxy temperatures!) and applied the last skins on the upper surface. Then as a real morale booster, the designer took a short break from his work in France, and came back to our area for the holidays. He looked over his finished "baby" and very closely inspected all aspects of construction. The verdict: he liked it!! I was hoping to have enough in place to perform the static load test while he was here, and have him supervise, but his recommendations were to wait until it is mounted on the airframe, along with the engine mount, and then load the whole thing up to 1,000 pounds, to better simulate real life conditions. He felt this would be a better test of not only the canard, but the fuselage and all attach points as well. The only problem would be in keeping sandbags from falling off, as it promises to be a skyscraper of a structure, just to get that much weight on the thing!
As of two weeks ago, the wheel pants are now attached, and I performed the alignment procedure following recommendations of Terry Crouch and others here to ensure proper performance and minimum tire wear. I'm not contouring them and hope to get at least one glassed this weekend. The elevators are also started, torque tubes prepared, foam cores hot-wired and joined, and now awaiting glass.
So I'm thrilled with the progress and hope to have reports regularly on mountains climbed and obstacles overcome. Now I know why they call this "an education experience". That's just what it's been, every step of the way! At least, I am learning!
Alan Thayer, Castro Valley, CA
When MODS May Leave You Standing
I had a talk with an AVEMCO rep at OSH about the liability suit article in Sport Aviation recently. He said they were the insurance company involved. The reason that they denied the claim was that the designer (Rutan) said unequivocally, that the Long-Eze needs fuel pumps and the mod that the owner did was not approved. If he had gone to the FAA and told them of his mod and gotten approval from them, it would have been all right. The FAA probably wouldn't have approved it because it didn't come close to the recommended fuel head pressure requirements. More important to this issue is that he told me that most states have a casual connection clause in their judicial system that says if you modify any device purchased from a manufacturer and that mod causes an accident, you are liable. This carries over to homebuilt airplanes in particular. In this case, if the cause of that particular crash had not been due to the fuel system mod, AVEMCO would have paid the claim. Although this is less severe than I originally thought, we still are expected to notify the FAA of any major changes to our aircraft.
Terry Sickler, Castle Rock, CO
THE SPINNER FRONT BULKHEAD
One of the little "difficulties" that I experienced building the Q-200 was the completion and fitting of the propeller spinner. I used the SN-4 Spinner Kit as supplied by Aircraft Spruce and Specialty Company. I spent a lot of time making templates for the propeller blade cut outs and Bob Waldmiller gave me an enthusiastic hand at accurately cutting the thing without completely screwing it up. The spinner ended up fitting and tracking very well. One thing was, however, missing from the package. You see, Aircraft Spruce does not provide a front plate for the hub thicknesses greater than 3-3/8".
I had noted that a good number of other aircraft builders had experienced success without the front bulkhead (i.e. and after all it was listed as an option in the ACS catalog). I flew my aircraft for some time without any kind of front-end support on the spinner. Then, guess what happened? I noticed some small hairline cracks in the paint at the notched corner in the spinner cutout on one side. After sanding through the paint and primer, I could see that my spinner had developed fine cracks. I had also noted that there was a resonance associated with lower power settings and certain angles of attack coming from the nose of the aircraft. I also noted that there was some degree of flexibility at the nose end of the spinner.
A friend mentioned to me that the spinner could be rewelded and that he had experienced the same thing on one of his aircraft. I went out and had my spinner rewelded. I primed it and repainted it. I reinstalled it and flew for several more hours. Then, guess what happened? I noticed some small hairline cracks in the paint at the notched corner of the cut out. Well, I talked to some builders and after I got several responses that said "they all crack". I then went out looking for a Kevlar spinner. My new composite spinner had no forward bulkhead either, but it was easy to fit up and attach; much more so than the aluminum. The only drawback was that it just didn't look as good. It also didn't have the precision fit of that aluminum piece of jewelry. Frankly, due to the characteristic abrasion resistance of Kevlar around cut edges, it looked like crap. So I went flying with the thought of one day attacking that forward bulkhead issue.
After talking with my hangar buddy, I got the idea that all I needed to do was have a good friction fit with any bulkhead that I was to put up front. All I needed to do was support the nose end of the spinner against torsional bending moments. I didn't want to try to do it in aluminum, because that looked too hard. I had severe reservations about squeezing any part of a fiberglass bulkhead between the prop and crush plate and taking the chance that it would disintegrate under load.
After looking at the problem for the last two years I figured that I could approach this thing from a simpler direction. I could use the 3/8" thick crush plate outside perimeter as the mounting surface to capture the bulkhead. The bulkhead is a snug fit around the crush plate and is held down around the plate by the snug fit of the spinner constraining it from the top. I fabricated this idea and it goes like this:
1. Laminate one ply of RA7725 BID with fiber orientation at 0 and 90 degrees to the edge of your layup board. Make certain that the ply orientation is straight throughout.
Lay a second ply of RA7725 BID at 45 degrees to the edge of the layup board. Squeegee and allow this two ply lamination to cure.
2. Locate, layout, straighten and tape down plastic wrap on a board of 10" by 10" or more. Find a center point for the lamination and create a small indentation at that center with a small drill bit. Using a compass, draw a 3-inch radius circle about the center point. Sand about and at least 1-inch outboard of the 3 inch radius line with 100 grit sandpaper until the surface is dull. Re-draw the 3-inch radius circle and use it to locate your 6-inch diameter (3/8" thickness) aluminum crush plate. Using the crush plate as a template, mark and carefully drill the prop bolt hole pattern into the fiberglass.
3. Remove the aluminum crush plate and apply one ply of 3M fine line tape to the outer edge of the plate. Allow the tape to overlap no more than 1/2 inch. Apply automotive finish wax or bees wax to the outer and inner faces of the crush plate.
4. Relocate the aluminum crush plate on the laminated fiberglass plate and secure using three prop bolts. Apply two-ply RA7725 BID around the edge of the crush plate on the taped surface only. Each ply should be oriented such that the fibers run 45 degrees to the top and bottom surfaces of the crush plate. Each ply should lap onto the sanded area of the fiberglass plate outboard of the 3-inch radius by 1/2 inch all around. This lamination will create a mounting ring about the aluminum crush plate. NOTE: During the lamination, there should be no contact between the epoxy and crush plate metal surfaces. Peel-Ply the surface that lap onto the laminated fiberglass plate. Allow this layup to cure completely.
5. Carefully measure the inside diameter of the spinner for the location at the top face of the propeller (i.e. the diameter at the fuselage station of the prop face/crush plate interface). Mark the location inside the spinner using a felt tip pen. Using a compass centered at the indentation of the laminated fiberglass plate, draw the inside spinner diameter on the fiberglass plate. Using a bandsaw, trim the plate to the inside spinner line.
6. Apply one ply of duct tape 1 inch above and one inch below the prop face fuselage station inside the spinner. Laminate 2 ply RA7725 BID on the duct tape inside the spinner. Peel-Ply the entire lamination. Do not allow resin to run down the spinner walls. After cure remove the Peel-Ply and lamination. Fill any surface imperfections with micro and sand as required. This forms the inner dome interface for the forward bulkhead.
7. Remove the aluminum crush plate from the fiberglass mounting ring and plate assembly. Remove the fiberglass from the plate assembly, which was below the location of the aluminum crush plate and trim to the face of the mounting ring. The plate and ring assembly should have a snug fit on the crush plate. If the fit is too loose, apply a light coat of micro epoxy and sand to fit.
8. Assemble the propeller, spinner backplate and crush plate. Place the fiberglass mounting ring and plate assembly about the crush plate. Place the fiberglass inner dome interface inside the spinner dome. Apply about 4 dabs of flox to the fiberglass inner dome interface and the fiberglass ring and plate assembly. Ensure that the spinner, prop and crush plate are appropriately masked off from any excess flow. Bring the spinner machine screws through to the spinner back plate. Allow the assembly to cure.
9. After cure, remove the spinner. The inner dome interface should be bonded to the ring and plate assembly. The forward bulkhead assembly is finished by laminating the inner dome interface to the plate assembly with two bias ply RA7725 BID. The final step is to trim off any remaining rough edges.
Finally, a spinner forward bulkhead of this type is currently flying on my Q-200 with my aluminum spinner. I have had no cracks to date with this arrangement. There are also no indications of harmonic rumblings at any power setting or attitude.
Brian Martinez, Quartz Hill, CA
The Q birds are strange creatures ... although I've only been flying mine 15 months and some 100 or so hours, I'd like to pass along what I've learned about some of mine's flying characteristics.
Anyone who attempts to prepare themselves for their first flight in a Quickie merely on the basis of myriad's of taildragger time will be completely unprepared if relying on that alone. True, it's better than no experience at all, but the resemblance to a taildragger about ends with the feel of the swerving tail and the relative motion of the nose while in a three-point attitude and that's about it. There is very little or no positive transfer of learning when it comes to, probably, the most important control, the elevator.
I'm certainly not saying that the ailerons aren't important, but except for their reverse control characteristics in the three-point attitude, they're just ailerons. This reverse characteristic is also common to many other tailwheel aircraft.
A Question of Gravity ... When the Q2 first flew with the lighter Revmaster engine; I suspect that its handling qualities were pretty good. Add the heavier O200 engine, a big panel and other stuff up front and you've got a nose heavy airplane. With a light tailwheel and a good sized vertical fin without much rudder, ground handling gets real interesting ... Couple that with a reasonably short stick and a relatively high stick to elevator travel (as per plans) and you've got a touchy airplane. Move the CG further aft and the problem only gets worse.
Consider the elevator. On most airplanes it's far enough aft that it takes quite a vertical displacement to make a rapid appreciable change in attitude. Most elevators are many feet from the CG. On the Q birds, it is a matter of inches. A small change in elevator position makes a big change in pitch. Move the CG closer to the center of lift (aft) and it really gets pitch sensitive.
When I'm flying by myself, I usually keep about five gallons of gas in the aft tank in the baggage compartment. It really helps keep the weight on the tailwheel. This is especially helpful with a crosswind. Add a heavy passenger and land with some fuel in the aft tank and it gets real pitch sensitive. Watch it in the flare!
I find a good technique is to check the position of your pitch trim just before you enter the traffic pattern. On one of my early flights I trimmed the airplane for about 75 kts on final only to pull off the power in the flare to find I had no more back stick available. I added a little power to stop the descent and went around. I noticed that I hadn't reflexed the ailerons nearly as far as I should have. Now I have a mark on the trim wheel that is what I reference for take-off. Stopped on the ground the elevator is trimmed so that it's about 2/3 of the way down. I trim it back to about this position on my trim wheel just before I enter the pattern, and then trim the rest of the nose down tendency away with the reflexor.
Speaking of a reflexor ... It's the most powerful flight control on the airplane ... If you want to get good take off and landing performance in your airplane, it's a must have item. It must be handy! I have mine mounted next to the throttle. As soon as I touch down and know it's a keeper, I deflect them full up. On a short field, I touch down with as much reflexor as possible, hoping to touchdown slightly tail first. My reflexor is rigged with an up movement only.
The next weird thing is the elevator on the landing roll. If you've ever had to use your brakes at a high enough speed to skid the tires, try pushing the stick full forward on the rollout. (Here's another thing that you'd never do in another tailwheel airplane.) The up elevator will spoil the lift on the canard while also pivoting the aircraft about the axles to a tail down motion, improving the tailwheel effectiveness.
I'm sure to many of you this is no news at all. I'm merely trying to pass along some ideas, especially to folks getting ready to fly. I'm very happy with the Q200's in-flight characteristics. Crosswinds are a challenge. I haven't attempted more than about 11 kts. I've only flown a couple of airplanes that roll quicker than this, and they're fully aerobatic airplanes. Yes the taildragger version is a little squirrelly, but given the drag penalty associated with the nosedragger, in my mind there's no question.
Al Kittleson, Denton, TX
I have been working a lot on the bird lately, installing an audio panel, which I built from a kit, RST Engineering. I have been cleaning up the engine compartment and improving a few things that I felt were questionable. I remote mounted the oil-sending unit, electric, to the firewall so that it would not be subject to vibrations. I have the oil filter remoted also, which brings up an article in a recent newsletter from Cary Thomas about no oil pressure. My engine has set for at least 10 years and after I mounted the oil filter, I wanted to try to send some oil up thru the engine to pre-lube it before I started it. Well, I turned the prop over a bunch to no avail; I just could not get any oil to come up to the filter. I finally thought that the oil pump might have lost its prime, so I decided to pour oil back thru the top hole where the oil cooler was originally. After pouring almost a quart backwards into the engine, it finally started pumping oil to the filter. Mind you, I have been hand propping the engine all this time, I didn't want to use the starter until I was sure that there was oil throughout the engine.
Bud Starnes, Mt. Vernon, IN
Jerry Marstall on the starting line of the 1998 Ottawa Race
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