CL Aerobatics
Frank McMillan, 12106 Gunter Grv., San Antonio TX 78231
THE FLYING SEASON is rapidly approaching as I sit down to write this column—not soon enough, actually. So I'll focus on a subject I haven't discussed in a long while: the handles we use to control our creations.
There haven't been many variations or much evolution in handles in the last 60-odd years. I remember my first U-Reely; the plastic one—not the original wooden model. I was in awe of how neat the concept of line storage and a handle all in one unit was.
The most successful early handle I had was the EZ-Just. What Control Line (CL) flier hasn't had a few of those?
There are many more factors in a handle than you might realize, and they affect the way you fly. I'll discuss these factors and how the dimensions and adjustments relate to the flier and the model.
Line spacing
Let's go back to the EZ-Just, and see what you could do with that simple design. It came in two models: the Hot Rock, with a four-inch line spacing, and the standard EZ-Just, which had a five-inch line spacing. That's the first parameter: line spacing.
Line spacing relates directly to the bellcrank size. In the early days—Classic and Old-Time eras—we had only three-inch bellcranks, so things were simple.
Most fliers had small- to medium-size hands, so they used the smaller Hot Rock. Those with larger hands had to use the standard EZ-Just, and live with the increased sensitivity.
I'll get back to spacing later, when I discuss adjustable handles and finish the EZ-Just discussion (the really basic handle) with line-length adjustment.
Line length and neutral position
The most obvious assumption with line length is that it's adjusted so that the controls are at neutral when the handle is at neutral. But that assumption has the potential for errors.
Empirically, there seem to be two hand-neutral positions: one with a vertical handle position and one with a slanted-forward handle position (with approximately a one-inch forward slant, sometimes more). This is a personal preference.
Most of the top fliers use the vertical-handle neutral position. It takes some fliers a bit of time to get used to it, but it gives the most even inputs—up versus down.
Four-time National CL Stunt Champion Jim Casale chose the slanted-forward (down-control handle position) as his neutral for several reasons. He didn't have a great deal of "up" wrist movement and he trimmed his models extremely nose-heavy.
The downward handle bias provided extra leverage for Jim for hard corners. However, realize that there is a bias in the control feel with this setup, and it requires a great deal of practice to overcome this bias/pressure difference.
Vertical spacing of your hand; this is approximately four inches.
Most of the "standard" control setups work well with this, but from then on it's dependent upon what your model and trim setup requires. From the initial flight on, you need to determine how much throw you require to match your wrist movement.
The corners must be comfortable, sharp, and with the bottom pullout height coming automatically. There is only one way to find out what effect changing the line spacing will have, and that is to experiment.
Move both lines together in small increments to start with (1/8- to 1/4-inch), until you get a feel for what you are doing.
Note that I suggested moving both lines up or down. Lines moved separately will change how fast or slow the control inputs are. You can use this to your advantage.
If your down reaction is fast or slow in relation to your up reaction, adjusting the down-spacing in toward the center of the handle will slow control input without affecting the up-control input.
There is a limit to this. If a gross control-input adjustment is required, the likelihood is that something is incorrect in the model's trim and you will need to correct that before continuing. Also, more than a minor adjustment will change your neutral setting.
Each adjustment in your handle will have an interrelated effect to some degree.
Overhang and geometry
Many of the newer handle designs have adjustments for overhang. Overhang is the distance from the vertical center of your grip to the pivot point of the lines at the front of the handle.
Overhang was a fixed distance on early handles, and we learned to live with it. The early Darwin metal handles had more overhang than the EZ-Justs, and a few good fliers used that to their advantage.
Ted Pachter wrote a column in a previous issue more than 10 years ago about overhang. The basic idea is to change the quickness of control input by varying the geometry. The closer the pivot point to the vertical center of the handle, the quicker the control input.
This translates into sensitivity near neutral. As you move the pivot point away from the handle grip, the neutral becomes more distinctive. Total movement is only slightly affected and only the initial rate of input is noticeably changed.
More overhang will yield a groovier model in level or inverted flight. It minimizes the effect of slight hand movements.
There is also a correlation between the length and thickness of the handle's cable to the effect of overhang. You want to keep the cable reasonably short as it exits the handle—roughly two inches.
If the cable is too long, there will be a vagueness to the control input. This is especially true with thick, stiff cable. A good choice for handle cable is .045-inch meter steel material. Do not use bicycle cable or leadout wire!
Grip and feel
In my many years of stunt flying, I've tried many handle-grip shapes, always looking for something better. The best grip for me has proven to be the first and second finger joints, as opposed to a wraparound, fully fitted grip.
The latter may look and feel good, but the problem is how the full comfortable grip affects wrist movement. As you tighten your grip, the wrist is constricted, slowing the input movement and restricting the movements to the extreme end.
I've often had to grind handles where the grip forced the line pull onto one or two fingers.
Please consider the grip an important part of the handle package, and give some thought as to how it relates to the entire package.
Final thoughts
I have said this lengthy discussion has taught you more than you'll ever want to know about handles. After all, they are quite simple.
However, the relationships give you a range of adjustments that can make your airplane come alive.
Transcribed from original scans by AI. Minor OCR errors may remain.
