Radio Control: Helicopters
Precaution to prevent crashes is helicopter Insurance. Most crashes are the result of two things - mechanical failure and human error. We will concern ourselves with the mechanical failure in this article. Ball-Links: These machines incorporate a lot of ball-links, and most of these links perform very vital functions, and a failure of any one of them usually results in disaster. Why and where do they fail? The most common failure is from improper installation. When they are screwed onto the threaded rod, the end of the rod should never go into the threads more than of the drilled hole. If the rod is screwed in further, it will rupture the ball-link, and you possibly won't know it until it fails. The beginning of the threaded rod should be smoothed off with a file or sandpaper so that the thread is smooth at this point. This is especially tru if you have cut off the threads with a Dreme~ disc or dykes. The sharp end of these threads literally cuts the ball-link so that it will fracture. Another failure of the ball-link is splitting along the mold seams. This is caused from inserting too large a threaded rod, and heat and fuel fumes that attack the nylon. On the Schluter ball-link, I use a collar made from blue nyrod. Cut a '/4-in, length of blue nyrod and slide it over the hex end of the ball-link, and it will never fail there.
Radio Control: Helicopters
The collective helicopter presents a very different set of trimming problems. Most collective helicopters operate at a much higher blade speed than fixed machines so in setting them up, the power curve of the engine must be determined. It is absolutely essential that the maximum blade pitch be reached on the up side of the power curve of the engine. It is also important that a near constant blade speed be achieved. Both of these factors are rather difficult to obtain so it will require some very precise adjusting. First, we need to make a visual device to quickly determine approximately 5/8 carburator barrel opening. On a Kavan this can be done with a dental mirror held up to the barrel and taking a look see, but to accomplish this, we have to stop the engine. This has to take time and may have to be done numerous times. A much easier method is to bolt a small aluminum plate about one in. high and 1 1/2 in. long behind the engine bellcrank. This can be 1/16 in. thick or less - whatever scrap you may have. Once bolted in place, it now needs to be calibrated.
Radio Control: Helicopters
Almost everyone has a pet engine that they invariably install in each new model they build. This will, in most cases, fulfill the power needs of the particular model: however, the helicopter is a different breed. To start with, your favorite engine ran out in front of the fast-moving model and was never loaded until vertical climb was called for. Also, it had an 11-12 in. fan turning somewhere near 12,000 rpm, Walt Schoonard forcing a great deal of cool, fresh air over the head. These are ideal conditions for your favorite engine. None of this holds true in a helicopter. To start with, the engine is usually completely closed in and has a loaded condition from about 4,000 to 14,000 rpm. It also has a muffler radiating heat like a pot-belly stove. The cooling fan is never more than 3 to 4 in. in diameter and quite inefficient. The end result is that your favorite engine has created an unbelievable lack of power problem. This lack of power makes for sloppy control, lack of blade speed, and an untrimmable helicopter. Because your machine won't lift off and the tail swings around opposite to the rotor direction, you begin to add pitch to the main and tail-rotor, and the problem gets worse. You then tweak the needle valve to get a few more revs, and the engine gets hotter, and so do you! After a flyless day, you conclude it is all the fault of these crazy machines that a friend told you would not fly anyhow. They are not crazy machines, and they will fly beyond your wildest imagination.
Radio Control: Helicopters
BETWEEN THE DOWNPOURS of rain that had deluged Louisiana for over a week, we set up the flying course equipment for the RC Helicopter event. The very amiable Deputy Cooper of the sheriff's department had the grass mowed, and the general flying area was clean as a whistle. Through Nick Nixon's efforts, I had all the good help I could use. He lined up the judges, the timers, and the couriers and had them there on time. Two years in a row this Lark's sparkplug has come through one hundred percent. Thanks, Nick, I couldn't have done it without you. Speaking of super help, Steve and Eileen Mintz flew from New Orleans to Lake Charles and worked through the whole meet. Eileen kept all the records up to the minute while Steve judged. This is the second year this young couple has done this at their own expense. Believe me, you meet some great people in this sport!
Radio Control: Helicopters
By the time you read this column, the 1975 Helicopter Nationals will be history. There will be some winners and some that didn't win but tried. Best of all, those that competed will have enjoyed the greatest part of this sport that of competing. By competing you will enjoy the fellowship of other pilots, learning from others, the development of skill, and the betterment of the machine. Almost anyone can learn to fly a helicopter, but it takes skill to compete. Practically any helicopter can be made to fly, but it takes development to make a machine competitive. If we are going to compete, we obviously need rules to govern the pilot and the machine. These rules cannot just be made up from imagination but rather from experience and trial. The following rules cover the pilot's experience, whether it be little or great. Rules should be challenging and yet be feasible. They should provide maneuvers with increasing difficulty so that a pilot will have a higher class to shoot for.
