Control Line: Aerobatics
Frank McMillan 12106 Gunter Grove San Antonio, TX 78231
Video series
Before I continue the discussion on flying from the March column, I want to call something to your attention that is really neat. You've probably heard that there are several series of videotapes made by Windy Urtnowski and distributed by Ken Budensiek (2522 East Milwaukee, Janesville, WI 53545; tel. 1-608/754-8921). The subject of one series is Windy's new piped ship (seven tapes), and the other is the construction of a Nobler kit (eight tapes). As can be seen, this is an extensive series. It is not a Hollywood production with special lighting, sound effects, etc.; it is one very knowledgeable guy doing what he obviously loves to do — constructing a fine CL Precision Acrobatic aircraft.
When Ken sent me the tapes, he wrote that one person had stayed up for two days watching them. I thought, "Sure. I'll just buzz through and look at some items that interest me." But as I got into the piped-ship tapes, I found there was always some kind of technique or procedure that attracted me. If you want to learn how to build competitive models of any kind, there is an absolute gold mine of the latest technology to be found in these tapes. You will find them candid, comprehensive, well done, and very, very difficult to stop watching. They are an excellent reference; clubs should invest in them as an instructional aid. They are really worth watching.
Using whipping to add energy
Last month we discussed looking at some fliers and the techniques they use to extract the last bit of performance from their planes. This month we're going to show you how to explore these techniques and work them into your pattern.
Anyone who has flown Control Line has played with whipping to some degree. Putting energy into the Stunter's system uses exactly the same principle but more subtly and for much shorter duration. Take two maneuvers, the Wing Over and the Four Leaf Clover, and experiment. Start with feeling how your plane responds to a little whip in level flight. Now get set for the entry into the Wing Over, and pull your arm toward you as you apply Up control. This is a coordinated effort and will take some practice to get it right. What you should experience is that the airplane will drive up and feel more positive. Keep trying until you find an effective, comfortable input. This also applies to the inverted pullup.
The Overhead Eight also benefits from a little help in the entry. The Four Leaf Clover can be significantly improved in two places: the entry through the upper sections and the top loops. Again, a combination of a little body/arm pull does the trick. It's the timing that is the secret, and that is purely a matter of practice once you find out how to do it in the first place.
The overhead entry to the Clover presents a lot of problems. You're bleeding off energy in climbing altitude, and then you must loop into the prevailing wind. Establish the altitude early, and take a step back (Bill Werwage and Les McDonald do this really well). The entry will be much cleaner and you will be able to set up better to complete the remainder of the maneuver.
The top loops in the Clover are sometimes soft; that's created by not having sufficient energy (which translates into line tension) to properly position the aircraft. Just as you applied "up" power in the Wing Over, get on it as the plane transits the bottom of the lower left loop. Properly timed, the plane will drive hard to the top of the track and go easily through the downhill loops to the lower right loop, where you repeat the same procedure. Remember that this is a timing factor, so it may take several repetitions to get just the right touch.
Next month I'll get into what to look for in the pit to give some insight as to how to make your plane perform better under varying conditions.
Tips
The first tip concerns warps. Everyone experiences this problem from time to time. What we're going to deal with here are a few "dos" to help you preserve that right dihedral surface you just completed and are starting to cover and paint.
- Always paint/cover the opposite side of any surface as quickly as possible after doing the first side so that the drying process does not introduce any uneven stress on the structure.
- Store your freshly painted plane and all its pieces (after they are out of paint) in a vertical position, so that you even out the drying/curing process. For the basic plane, adjust the holding fixtures so that the tail is pointed straight up. For the fuselage surfaces, align your holding jig so that the hinge lines are vertical.
- Use holding fixtures for surfaces when possible.
Unfortunately, bad things happen, and on occasion a warp will creep in anyway—usually a bow in the flap. Try the following procedure. It has worked well for me for many years.
Drying jig for warped flaps
What you do is construct a simple drying jig that holds the surfaces in alignment while the paint takes a permanent set.
- Cut a piece of scrap particle board or plywood approximately 30 in. long. Draw a straight line down the middle of the board lengthwise. Glue a piece of 1/4-in.-sq. balsa on that line. Each side of this piece will be the straight reference edge for the fixture.
- Take another piece of 1/2-in.-sq. balsa, and bevel the side which will be glued down to the board, thereby forming a tapered slot between it and the "master" piece of balsa. Measure the separation so that the space will cradle the trailing edge of the flap (which you are going to put in the slot) snugly, holding it dead straight but not allowing the trailing edge to touch the base plate of the fixture.
- Do the same for the other side of that first 1/2-in.-sq. piece of balsa. This will give you two parallel slots in which to insert your flaps.
Give the flaps another coat of paint, and allow it to set up for about 20 to 30 minutes. Then insert the flaps, trailing edge first, into the drying jig. Push just enough to get a firm hold. You will see the flap form to the straight edge of the jig. Let this sit up overnight, and you should have a good set of flaps. Note that you may have to repeat this procedure for several coats of paint, but it does work. Be persistent.
Transcribed from original scans by AI. Minor OCR errors may remain.
