CONTROL – LINE
Round & Round You Go!!!
Learning to Fly Control-line Model Airplanes
Learning to fly control-line model airplanes is not as simple as one might think. Over controlling is a common problem with beginners; on takeoff too much up control is used causing the plane to zoom skyward at an impossible angle, the natural reflex is to apply down-elevator, but too much is applied which starts a succession of up and down gyrations that can end with an abrupt meeting with the ground. One technique that works well for beginners, is to keep your arm rigid and only move the up and down while keeping your elbow and wrist rigid.
Further complicating the flight of the control-line model is the fact that sufficient centrifugal force must be maintained to keep the tension needed to control the models up and down movement. This is especially true when the model is flying on the upwind portion of the circle, where the wind will be pushing the model inward slackening the lines.
There are techniques to cause the model to fly outward at all times. Most common is having the rudder turned so as to direct the model outward. Another technique is to have the engine thrust line titled outward. Sometimes weight is put in the tip of the right wing.
Any Ideas on Making the Learning Easier
In teaching beginners, I find they just can not seem to get over controlling. I have thought of putting stops on the bellcrank so as to allow little up and almost no down. If anyone has any ideas, please e-mail.
Comments
Beginners do best if someone helps them with the first couple of flights, either with a trainer type handle, or simply holding a hand over theirs.
The plane should be a trainer type- nose heavy, realtively large tail, mechanically very slow controls. Use the innermost hole on the bellcrank, a tall control horn, and a large bellcrank, so everything is set up to require the most movement of the handle to get from full up to full down. If the plane can manage a loop, it is probably set up too sensitive.
The Midwest Half A Warbirds do work pretty well. They are relatively easy to build, stable, and hold up pretty well if flown over heavy turf. I met several kids this summer who had built one of these and taught themselves how to fly. It helped that one of the dads involved was a machinist and pretty on the ball mechanically though.
PhilBill,One thing that helps, rather than installing stops on the bellcrank, is to ensure that the training aircraft is set up with a very short moment/distance between the bellcrank pivot point and the pushrod connection point (Tom Dixon uses 3/8″ in his stunt ships) and placing the pushrod to the max distance away from the control surface on the elevator control horn. PIO is exacerbated by sensitive controls; reduce the sensitivity to reduce the severity of oscillation onset. Most of us as young control liners figured that “more was better”; thus we put the pushrod in the hole furthest from the bellcrank and positioned it on the elevator such that we virtually created an airbrake from the extreme deflection of the control surface.
Couple of years ago, I designed a training handle that uses two handles that sit in tandem to each other, with a lateral separation at 1.75 inches. Specifically, I used two short pieces of 1×2″ pine and mounted the two handles such that they were on opposite corners of the rectangular 1×2″ pieces. The trainee holds the handle closest to the airplane and the instructor pilot (IP) the handle furthest from the airplane. Once the IP releases his grip on his handle, that handle then rests against the forearm of the trainee, essentially enabling him to use it to keep his wrist stationary. This, along with the de-sensitized controls, virtually eliminates PIO. There was a picture of a handle with forearm brace from “yesteryear” in a recent issue of PAMPA’s Stunt News that accomplished the same thing. Hope these thoughts help!
Chip LargentNorfolk AeromodelersVirginia Beach, VA
The Rittenhouse Electric Aircraft
Possibly a predessor to the control model airplane, was an electrically powered model airplane produced by the A.E. Rittenhouse Company of Honeoye Falls, New York. Introduced in 1913 and produced for almost twenty years, these models would take off and fly in a circle by a combination of centrifugal force and the power of the wings while tethered to a revolving ceiling fixture by two light wires. The heart of the system was the special swiveling counterbalance mounted on a screw hook that was inserted in the ceiling of the room where a model was to be flown. Electrical power was from 6 to 12 volts a.c. or d.c. and could be operated from dry cells, a storage battery, or alternating or direct current by means of a transformer or direct current reducer.
The first model airplane introduced by Rittenhouse in 1913 was a 22-inch wingspan model of a Bleriot that could be flown in a circle of 5 to 100 feet in diameter and would attain an actual speed of 12 miles per hour on 8 dry cells. By 1915 two more airplanes had been added, a smaller 16-inch Bleriot and a Curtiss biplane.
Propeller Pitch
Pitch is the horizontal distance the propeller will screw forward in one complete revolution. The pitch number can be used to determine the theoretical speed that any combination of motor and propeller will deliver. Propellers are sold by using the diameter and pitch. For example an 8×6 propeller would be 8 inches in diameter and have a 6 inch pitch.
Example Computations
6″ pitch x 17,000 rpm x 60 (minutes per hour) 12 (inches per foot) x 5280 (feet per mile)
6,120,00063,360
= 96.59 miles per hour With No Drag
Drag will vary but 30% reduction is likely
96.59 x .70 = 67.61 Actual Miles Per Hour
