There is a way to master the art of throttle control. If you want to know the secrets, this article will reveal the tried and tested method for smooth, positive throttle control.
Aviation can be a very humbling experience and mastering the art of throttle control is but one aspect of this experience. Allow me to explain. When your urge to fly overwhelms you and you seek out flying lessons, you step into a world of process and practice. It all comes together as a series of ‘firsts,’ the first time you are actually flying to your first landing. It is exhilarating, exciting with a touch of scary if you are truthful to yourself.
“On one of my check rides, my instructor marked me down for throttle bashing and being out of balance. I hadn’t been smooth enough on power application, which made it hard to keep the balance ball centred and the aircraft trimmed. When I got better at throttle control, it made all aspects of primary flight control easier.”KEN, REFLECTING ON RAAF PILOTS COURSE IN THE PC-9/A TURBOPROP TRAINER
You have control; the aircraft responds to what you give it, and this can be smooth, positive and balanced or it can be jerky, out of balance and unstable. It is important for a new pilot to understand that it is ok to learn by rote to start with, but as you progress you can strive for mastery and knowing some of the secrets can help you get there faster. By mastering the art of throttle control, you can flip from rote to instincts and in this article, we pass on the secret handshake!
What is the purpose of the throttle?
The throttle control in an aircraft is where the pilot controls the power output of the engine. It achieves a change in power by controlling the fuel flow provided to the engine.1 Remember in a typical piston engine trainer, we are creating a controlled ‘explosion of fire’ in the cylinder and to achieve a fire we need a mixture of fuel, air, and ignition2. In short, more fuel and more air means more power output,3 and this is controlled by the pilot via the throttle levers.
What are the different names for the throttle control5?
There are several names for the item that controls the fuel delivered into the engine and without disappearing down a rabbit hole, it is good for any newbie learning to fly to at least understand that there are different names attached to control levers, for a different purpose. These can be argued however to maintain order in this article we will cover just a few.
Throttle lever usually refers to an engine with a carburettor where the throttle valve opening delivers the desired fuel/air mixture to the cylinders, OR an engine that is fuel injected where fuel is ‘injected’ more evenly to the cylinder.
Power lever usually refers to an engine that is powered by a turbine, for example a turbo prop aircraft.
Thrust lever usually refers to jet engines as it primarily produces thrust.
What are the Dangers of Throttle Bashing?
In a typical light piston training aircraft, throttle bashing can be detrimental to the aircraft – a throttle basher could be said to ‘lack mechanical sympathy’ – rapidly advancing the throttles on engines that have pendulum dampers on the crankshaft can cause excessive wear and tear – I know of one pilot who slammed the throttle back and forth on his Cirrus only to find the throttle lever broke off when he slammed the throttle close on landing (resulting in the engine spooling to full power – they chose to select the mixture to idle cut off and managed to land, albeit halfway down the runway).
Personally, on my second solo flight, I pushed a bad approach only to get down to 100ft well outside the landing strip before electing to go around – I hastily jammed the throttle lever of the Cessna 150 forward instantly, only for the engine to quit – and as a result, I landed on the grass undershoot! Lean misfires are common if you jam carburetted engine throttles forward too quickly, especially in aged engines where compensators (like accelerator boost pumps) may not be working as they did when brand new.
However, some of the other dangers come in the form of losing control in high-performance tailwheel aircraft – such as a mustang or even agricultural aircraft such as a thrush or airtractor – rapidly jamming the throttle forward on take-off could very quickly lead you to being sideways across the runway due to the slipstream and ‘p-factor’ effects!
During my time flying turboprops, we always had a fadec that digitally connected the power levers to the engines, so if we needed power for an engine failure on takeoff we could slam them forward (or rearward) however we would still have a control issue as a result due to the near instantaneous delivery of power from the large propeller mass – the blades twist providing the instant power increase. Slamming the power lever forward in an assymetric situation was always avoided, and smooth, gentle (but positive) power control was always favoured to maintain safe control of the aircraft.
I have never flown a jet aircraft personally, but my colleagues that do have told me that their ‘toga’ (take off and go around) button automatically commands the thrust levers to max thrust, and due to a lag in power delivery in a jet this was not really an issue.
How does the throttle control affect the aircraft’s attitude?
The first fundamental skill to learn when it comes to mastering throttle control is how to adjust power while preventing attitude deviations. Going deeper again, we need to look at why the adjustment affects the attitude in the first place, and to keep it simple it is the relationship of the thrust line to the aircraft’s center of gravity and flow of air over the tail surface.
When you adjust power with the throttle control in a C172, you are disturbing the equilibrium or balance of opposing forces. When you increase power, and the thrust line is below the center of gravity, the nose will pendulum the aircraft nose up/tail down if nothing is done. As the thrust line in smaller aircraft is only slight, the slipstream over the tail also has an effect where the slight downdraft from the rear of the wing creates a bias downwards on the tail, and a yawing motion to the left.. With more power, more slipstream increases the tail-down bias.
Anticipation is the key, and the great thing is you can practice counteracting any power change. Pick a line on the horizon while holding the aircraft in a given attitude, e.g., climb, level, or descent; smoothly reduce power to idle, and increase to maximum while maintaining a constant attitude by coordinating the pitch controls. Power adjustment and power setting should ideally be practiced without reference to the engine instruments at all, only using perceptions of power through sound, acceleration forces, throttle position, control pressures, and effectiveness.
With practice, you will anticipate that (for most conventional aircraft) an increase in power will require simultaneous forward pressure on the stick, and right rudder input to remain balanced, which can then be trimmed appropriately, and vice versa for reduction in power.
How to use the throttle control instinctively?
By developing all your senses, it is possible to develop your throttle control skills to fly instinctively, instead of mechanically. To be able to perceive subtle movements in pitch, roll, or yaw, it is useful to imagine the longitudinal axis extending through the propeller spinner to infinity out the front and through the tail out the back. By imagining that bigger picture distant view, you will be able to perceive when the aircraft’s attitude is moving subtly away from its desired position and make corrections before they become obvious.
The visual focus should also be as broad as practicable, so a broader and deeper perspective is gained than if you are focused just in front of the aircraft, the instrument panel, or at the horizon.
How does the throttle affect flying in balance?
The best way to fly straight in balance is by ensuring the wings are level first by comparing the distance of the wingtips to the horizon, then while holding them perfectly level, watch for any change of heading. If the wings are perfectly level, and the aircraft is slowly turning, use the rudder to prevent it. Once a constant heading is established, if you scan to the balance ball and it is not in the middle, the balance indicator is possibly not set into the dash correctly rather than the aircraft being out of balance.
That is the practical definition of balanced flight, which indicates that the aircraft is flying directly into the relative airflow. If the aircraft is slightly skewed to the left or right, form drag would be increased, which suggests another way to conclusively verify whether the aircraft is in balance or not. Compare flying with the wings level using rudder to prevent heading slowly changing to the left or right, then try it with the balance ball centered – even if the wings are not perfectly level. Whichever yields the higher airspeed indicates true balanced flight. Unless there is some problem with the aircraft’s rigging it will be marginally faster with the wings level.
Learning to fly is an honor bestowed upon true aviation lovers and it comes with risks and challenges. The nature of defying gravity as we do is that the training process needs to start as a rote learning style as we initially need to create muscle memory. When it comes to mastering the art of throttle control, and to control altitude, understanding the theory is the beginning, learning to anticipate the pitch change is the middle, and mastery comes when this all switches to instinct. Mastery is sneaky, however, as you will not know that you have it … until you have it.
So, until you know you have it, keep working through the process and apply whatever tools you have at any experience level as one day everything will become slightly easier and smoother and it will be then you realised it happened. Remember, going back to basics is not ever a dirty word, all pilots at every experience level, whether in older or more modern aircraft, do this whenever it is required. Aviation is an extremely rewarding gift however never forget that the most important measure is simply coming home safe.
- Carburetor mechanics, Amy Tikkanen, Britannica. Accessed online at https://www.britannica.com/technology/carburetor on Sep 28, 2022.
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- Understanding your Lycoming Fuel Injection System, Jacqueline Shipe, Cessna Flyer Association. Accessed online at https://www.cessnaflyer.org/maintenance-tech/item/1150-understanding-your-lycoming-fuel-injection-system.html on Sep 29, 2022.
- ‘Throttle Lever’, Skybrary. Accessed online at https://skybrary.aero/articles/throttle-lever#:~:text=Description,with%20which%20it%20is%20associated. on Sep 29, 2022.
- Aircraft Engine Controls, Wikipedia. Accessed online at https://en.wikipedia.org/wiki/Aircraft_engine_controls on Sep 29, 2022.
- ‘Power And Pitch’, Jeb Burnside, Aviation Safety Magazine, Published: June 30, 2019. Accessed online at https://www.aviationsafetymagazine.com/another_look/power-and-pitch on 08 Sep 2022.
- Basic Flight Maneuvers, Airplane Flying Handbook, FAA. Accessed online at https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/05_afh_ch3.pdf on Sep 29, 2022.