by Yasmina Platt
Published in Midwest Flyer – June/July 2017
I recently added “Rotorcraft – Helicopter” to my green plastic certificate and I quickly learned that science is what gets helicopters in the air, but art is what keeps them flying. Flying a Robinson 22 is like flying a low-to-the-ground sporty convertible with fantastic visibility, maneuverability, and versatility. Learning to fly one made me feel more like a juggler than a pilot.
The differences between airplane and helicopter flying are immense. So much so that it did not feel like “just an add-on” or transition training; it felt like learning to fly all over again.
I only found a few things transfer or are helpful when transitioning to helicopters, to include pilot privileges and limitations, weather, communications, or regulations, to name a few; however, most of those affect helicopters slightly differently.
The rest is pretty much another world. The obvious difference is the fact that helicopter pilots sit on the right side, but there are a lot more: 1) aircraft capabilities, performance, and limitations, 2) many more aerodynamic theories and applications, 3) flight controls and systems, 4) weight and balance considerations, 5) safety around helicopters, 6) flight operations, maneuvers, and procedures, and 7) emergencies and hazards.
I will now highlight some particularly interesting examples here; however, for a copy of this entire article, visit www.airtrails.weebly.com/other.
The word “helicopter” is linked to the Greek words “helix/helikos,” which means “spiral” or “turning” and “pteron,” which means “wing.” So, the four principles of flight apply to both types of aircraft; however, helicopters have a long list of additional aerodynamic principles we do not study in “airplane training.” Some of those include dynamic rollover, low G/mast bumping, translating tendency or tail rotor drift (somewhat similar to an airplane’s left turning tendency), dissymmetry of lift (on both the main rotor and the tail rotor), Effective Translational Lift (ETL), catastrophic rotor stall (very similar to the stall of an airplane wing at low airspeeds, except in helicopters, it occurs due to low rotor RPM, instead of low airspeed), and Loss of Tail Rotor Effectiveness (LTE).
Yes, helicopters are incredibly capable, but I was surprised to learn about their limitations (e.g. not being able to hover out of ground effect in certain conditions) and things you can do but you want to minimize doing (i.e. the height-velocity diagram in the R-22). I mean, really surprised. There’s a lot to take into consideration. They are not quite as “superman” as I thought…
I also would have never thought changing frequencies would become one of the hardest things to do, but I initially found it to be that way. Even though some helicopters (like Robinsons) have trims, they are not like airplane trims, where once you set it, the airplane will stay pretty stable and you can let go for a while before a correction is needed. You literally cannot let go of the cyclic (right hand), and some helicopters have pretty sensitive collectives (left hand), making it hard to let go of it in order to change frequencies, look at charts, etc. I learned that the only safe way to do it was to temporarily set the collective’s friction lock to keep it from lowering immediately.
Oh, and how in the world did people fly, without doors, and paper charts in helicopters just a few years ago? Phew! How did they manage to flip it to the right area? I want to bow to them.
While going slow in an airplane is frowned upon (and rightfully so), it is one of the most beautiful things in helicopters. But, I’m not going to lie…the transition from seeing the airspeed indicator go from an approach speed of about 60 kts in a small GA plane, to close to 0 kts for a steep approach in a helicopter, raised up my blood pressure a bit at first.
I see no real Center of Gravity (CG) difference between flying an airplane solo vs flying one with another flight instructor or passenger. But, whoa, that is not the case in a helicopter. It is way different! With both seats occupied, the helicopter is pretty balanced. However, when you remove the left seat weight, it is no longer balanced and pilot inputs need to counteract the difference in acting behavior. When picking up by myself, I had to add a good amount of left cyclic (to counteract the weight difference) and left pedal (to counteract translating tendency). When setting down, I had to lower the collective firmly so it did not lift again as it was lighter than normal. The helicopter also had a tendency to go backwards in both scenarios.
I can also understand now why most dual rated pilots will not fly both types of aircraft on the same day. The question is not whether or not a person can fly both safely in normal conditions, but whether that person will react to an emergency correctly should one occur. All aircraft have different systems and work slightly different, but in an emergency, these contrasts could cause a pilot to confuse one for the other and the brain/reflexes may not react correctly.
For example, recovering from what may sound like an airplane’s “stall warning horn” in a helicopter (low RPM instead) could result in a fatal accident.
What is the first thing you do in an airplane when recovering from an aerodynamic stall? Fairly aggressively lower the nose, right? Well, doing that in a helicopter: 1) actually lowers the RPMs even more, which could result in a rotor stall (especially if the pilot also adds power by raising the collective), and 2) may cause a low G/mast bumping situation which, in turn, results in main rotor shaft separation and/or rotor blade contact with the fuselage. Ouch! In addition, airplane pilots do not normally pay attention to RPMs after they have lost the engine, just airspeed. However, if you lose the engine in a helicopter, controlling rotor RPM (and airspeed although in a second place) means life!
There is no question helicopters are far more expensive, versatile, and challenging than airplanes, but nothing worthwhile comes easy in life.
Special thanks to The Whirly-Girls for selecting me as their 2016 Helicopter Add-on Flight Training Scholarship recipient and giving me the opportunity to fly these incredible machines we affectionately call “choppers.”