Plane, Gyro or Copter

SO YOU WANT TO FLY? In what type of machine? This question is asked by flying fans millions of times, it seems. In my 30 years of flying and aviation experience I do not feel this question has been fully appraised and fairly presented to impartial observers.

I believe the answer to this question lies with you, the man in the cockpit; what are YOUR desires?

Do you wish to take off from a point “A” (from a prepared airstrip) and fly to a point “B” (another prepared landing strip) in the most efficient manner and at a relatively high rate of speed, but with poor slow speed control, and none below the stall speed?

Or, do you wish to take off from a comparatively small clearing, fly at a reasonable rate of forward speed. Maintain full control of your machine at all airspeeds even down to 0 mph, and be able to land in a clearing 3 or 4 times the size of your “wing span”.

Or, do you wish to take off vertically, fly at a relatively slow forward speed, with poor efficiency, be able to slow down to 0 mph forward speed and even hover over a spot, paying for it in mechanical complexity and high cost?

In reality the answers to these questions are inherent in what type of wings keep your machine up in the air. Are they fixed? Are they rotating? If so, powered or unpowered? How will they fare under unusual or abnormal flight conditions that you are certain to encounter such as foul weather, gusts, down-drafts, slow speed controllability, engine and other mechanical troubles, misjudgement etc.

The key to understanding the differences between all these heavier than air flying machines is in the diagram shown here. The three curves plotted represent characteristic performances of an aeroplane, an autogyro and a helicopter. What really brings out their differences is their rate of climb when it is plotted against airspeed. There is a goldmine of information in these curves. Lets look at them one at a time.

Starting with the aeroplane, we see that it is the most efficient of the three machines because with the same horsepower it has the highest rate of climb. It is also capable of the highest airspeed. But notice also that at speeds below about 60 mph its rate of climb goes negative and goes out of

sight. The aeroplane stalls and literally quits flying. No amount of your cockpit jockeying will keep it flying at stall speed and below. For the same reason the aeroplane can never touch the ground at speeds slower than 60 mph when ending or beginning the flight.

Next look at the autogyro. Less efficient and less speedy than the aeroplane, but look what happens at slow speeds. Its rate of climb goes down to zero at about 20 mph, but does not disappear out of sight. Instead it curves at a gentle slope and has a finite value even at zero airspeed. You fly this machine under full control even when it descends at zero airspeed. At negative speeds (flying backward) it flies without dropping out of control until it weathercocks into the wind and re-establishes forward flight.

The rotor of an autogyro can be tilted into the wind at a very steep angle of attack without stalling, while fixed wings stall at 30 during the takeoffs and 45 during landings. This characteristic permits the gyro to slow down to airspeed of 7-10 mph during landings with ample time reserve to jockey for a gentle touchdown. The helicopter curve shows it to be still less efficient and slower than the aeroplane, or the gyro, but its rate of climb never goes below zero. This means that at no time will this type of craft be forced to lose altitude no matter how slowly it flies. This is a tremendous bonus, but observe the shape of the curve. Rate of climb is much lower at zero airspeed than at cruising speed. Think for a moment what this means. It means that to fly slower, it takes more power than to cruise. This is opposite to what happens in automobiles, or in boats, or in any other ground conveyance.

This is a paradox that is peculiar only to aircraft. In all fairness to the helicopter, I must say that this reverse power-speed curve applies to other flying machines as well, but the helicopter is the only one that extends the speed range all the way down to hovering. And since it is capable of flying safely at very low speeds without sinking, it spends considerable time in this regime of operation. I might add that this low speed and hovering ability exists only when the engine develops full power. When the engine is sick, or when you fly the helicopter under high temperature, humidity or altitude conditions, the left side of its curve slips down below the zero line. Its performance curve then resembles that of the autogyro except not as efficient in the higher speed range. A pilot who tries to fly the machine as a helicopter under these conditions is in for a lot of surprises. Many helicopters have been lost when they refused to flare for a hovering landing and “fell”, as if through an invisible hole. Similarly, many crashed on the takeoff being unable to go into forward speed from hovering in ground effect and “fell” to the ground when they slipped off the ground cushion.

Last, but not least, when their engines conk out completely, helicopter pilots have only 2 to 3 seconds to convert the machine into an autogyro. When they don’t, their rotors slow down and fold up with disastrous consequences. As an autogyro (really, a gyroglider because its power is off), a helicopter is considerably less efficient because of its higher disc loading. This gives it a much steeper angle of glide and requires critically shorter timing to flare out for landing.

Now put yourself back into the cockpit of your dream bird and start imagining. Everything that goes up must come down. Birds have been doing it for millions of years without crashing, smashing into mountains, stalling out on landing approaches, etc. How will your mechanical bird fare in situations such as engine failure near the ground? Ditto on the takeoff? Running into rapid wind shifts?

Running into sudden foul weather. Running out of fuel? I am sure you can think of many more. There is no use saying, “It won’t happen to me” It happens to the best of people and to the best machines. Just as cars have flat tyres, and breakdowns even though you bet every day they won’t. What matters is when (notice I didn’t say if) these extraordinary situations happen, your vehicle, on the ground or in the air must give you the maximum chance of keeping it under control and protecting your safety.

Now look again at the curves and decide for yourself what kind of bird you would rather fly in all these situations. I will not presume to play a prophet or an “expert” and will not attempt to say which one is the “best”. The choice is up to you. I just wanted to make sure you had solid and significant facts for the basis of your choice. Remember, YOU are the man in the cockpit