RADIO CONTROL SCALE AEROBATICS
Eric Hawkinson, 319 Yellowstone Ave., Billings MT 59101
Introduction
When we last visited, I gave you a description and a chart to help you work on the four-point roll. Although I wrote about knife-edge flight before, you probably found plenty of challenge in perfecting the four-point roll.
For many pilots, the most uncomfortable part of the four-point roll (from upright) is the quarter-roll from inverted to the second knife-edge. That's because most people only work on knife-edge flight by rolling fairly quickly from upright to the 90° position, then quickly quarter-rolling back to upright.
Even if you are thoughtful enough to practice the maneuver in both directions, you get used to adding rudder in the opposite direction of aileron. That's okay when you are rolling quickly, then adding the rudder, and when you always start from upright.
When you roll from the inverted position to second knife-edge in a four-point roll, it may feel strange to use rudder in the same direction as aileron, even though you know that it is correct. I can't give you any hints to get past this; as in many parts of flying, the only cure is to spend time practicing the maneuver and getting comfortable.
Goals for the Four-Point Roll
- Keep the line you are rolling on straight and level.
- Center the maneuver properly.
- Make the segments equal in length.
- Keep roll rates consistent.
As long as you're going to take the time to learn the maneuver, you should learn to do it well!
It would probably be helpful to have a friend watch you fly and give you some feedback on how you're doing. Sometimes we get so busy flying a maneuver that it's hard to honestly evaluate the results of our own efforts.
If you are getting complacent with the four-point roll from upright, go up to a safe altitude and try it from inverted. Don't be discouraged if you have trouble with the new attitude—most pilots do. Think it through, reverse the direction of rudder inputs (first quarter-roll: same rudder; third quarter-roll: opposite rudder), and work it out.
The Eight-Point Roll
Moving a bit beyond the four-point roll, how about trying an eight-point roll? They are really fun to do, and quite enjoyable to watch.
An eight-point roll is a four-point roll with hesitations added at each 45° of roll. Thus, the first portion is a roll to 45° of bank, a roll to 90° (knife-edge), 135°, inverted, etc. But hold off on the eight-point roll until you are comfortable with four-point rolls.
I've seen the jet guys do eight-point rolls without ever touching the rudder. Too bad—they miss all the fun. Your scale aerobatic mount will not allow such simplification; in fact, the eight-point roll will require that you master the smooth application of rudder and elevator.
While you can get lazy and wait to apply the "trim" inputs (rudder, then elevator) at each 90° position in the four-point roll, this will not work in the eight-point roll. You may need to make inputs for rudder and elevator at each position of the eight-point roll, except for the inverted portion, and hold them for the duration of the hesitation.
Enter the maneuver from upright flight, with as much room in the maneuvering area (box) as possible so you don't get too rushed.
Eight-point roll, suggested sequence and control inputs:
- Roll to 45° (halfway to knife-edge).
- Start applying a bit of rudder as soon as you start rolling, in the opposite direction of the aileron input.
- With some airplanes, a small amount of up elevator is needed to maintain heading.
- Hold the point briefly.
- Roll to 90° (knife-edge).
- If you needed up elevator at 45°, release it during the roll.
- Add the rudder required to hold knife-edge.
- Hold briefly.
- Roll to 135° (halfway between knife-edge and inverted).
- Release about half of the rudder you were holding for knife-edge.
- Add a small amount of down elevator to maintain your line.
- Hold briefly.
- Roll to 180° (inverted).
- While rolling, release the remaining rudder.
- Add the down elevator needed to maintain level flight while inverted.
The other half of the maneuver is the same, except that the rudder and elevator inputs are reversed. When you are learning, you can certainly ignore the elevator inputs except while inverted. If you keep the hesitations short and the eighth-rolls fast, elevator won't matter as much, and even the rudder application will be less critical. There's nothing wrong with keeping it simple for the first few sessions.
As you get more comfortable, do yourself a favor and slow it down so that you can really enjoy it. The eight-point roll is such a great maneuver, and so impressive to watch, that it's certainly worth whatever number of sessions it takes to master.
Next time I'll write briefly about the slow roll, which is basically an eight-point roll without the hesitations. By the time you master that maneuver you will certainly have developed a fine degree of "touch" on the sticks!
Knife-Edge Circles
Meanwhile, you may want to have a little fun with a much simpler maneuver that will serve to impress the spectators. Having mastered "simple" knife-edge flight, why not work on a knife-edge circle?
This fun maneuver is not much harder to do than a knife-edge pass, except for getting used to seeing the model in a new attitude relative to your position. That's a fairly big "except" though, so move the airplane out and up to keep things safe.
Inside (up-elevator) knife-edge circle — steps:
- Start with a normal knife-edge pass.
- When the airplane is in the center of the box with the bottom of the model toward you, pull in a bit of up elevator so the airplane will turn, in knife-edge, away from you.
- Use rudder as needed to maintain altitude.
- Adjust the diameter of the circle with elevator.
- When you have completed a circle and are back at center stage, release the elevator (only), and finish the knife-edge pass.
Outside (down-elevator) knife-edge circle — steps:
- Roll so you are looking at the top of the airplane before you push elevator.
- Use down elevator to make the airplane do a circle that starts by going away from the flightline.
When inside and outside knife-edge circles feel good, put them together: do a knife-edge "8" by changing the direction of elevator input as you complete the first 270° of a circle, then after you complete the second circle. (This has you changing direction without coming closer to the flightline than your starting position, assuming that your circles remain round.)
Gear and Kit Notes
Enough about flying for now. Let's discuss goodies!
I looked at the Hangar 9 Almost Ready-to-Fly production of the CAP 232 at my local hobby shop. This looks to be an excellent value, but my anemic checkbook kept me from grabbing one on the spot for my amusement.
All of the building is done, and looks to be done quite well. The cowl and parts are molded from fiberglass, not plastic, and come already painted to match the UltraCote covering that is already applied. You'd have to do some extra work to make this kit not turn out looking good.
Even the size is in my preferred range: a 73-inch span with 1,031 square inches of area, made for .120 to .150 power. The control surfaces are beveled to allow extreme throws needed for the more radical 3-D style of flying, while a target weight of 11–12 pounds will make it tame enough for any moderately advanced sport flier to handle with ease.
All of this makes the kit a very appealing choice, but I haven't even mentioned the part that really amazes me: a street price of less than $350!
I hope to get a chance to fly one of these soon. If it flies as well as several reports indicate, I may have to find a way to squeeze the budget to pick one up.
The Hangar 9 line is distributed by Horizon Hobby Distributors, which means you should first check with your favorite hobby shop. If it doesn't have the kit, call Indy R/C (Horizon’s retail discount outlet).
That's all for this time. Have fun, and fly safely! — JY
Transcribed from original scans by AI. Minor OCR errors may remain.
