Flight Technique/Conquer Dead-Stick Landings
Understanding energy management is key
Anyone who has flown model airplanes for any length of time has had an engine failure, with the resulting distinct “pleasure” of performing a dead-stick landing. It doesn’t matter if the engine is nitro, gas, electric, or a ducted fan—all engines are mechanical and are, therefore, subject to some kind of failure over time. When you are put into this situation, however, the outcome of the approach and landing will greatly depend on your understanding of energy management.
ENERGY MANAGEMENT
When an airplane loses its engine, it has two basic forms of energy. The first form of energy is determined by the speed of the airplane, which is its kinetic energy. The faster the speed, the greater the kinetic energy. The second form of energy is potential energy, which is determined by the height, or altitude, of the airplane. The higher the airplane, the greater its potential energy.
It’s also important to know that these two forms of energy are interchangeable and that they depend on each other. As an example, if you are in a glide with excess airspeed, you can pull back on the elevator and climb. As the plane climbs it will lose airspeed, which means the kinetic energy of the plane is being transferred into an increase in potential energy. In a similar manner, when in a descent, the potential energy of the plane is being decreased to increase, or maintain, its kinetic energy. This is, unfortunately, not a one-forone trade because of the drag of the plane. This is the exact theory in flying a glider: trading altitude to maintain airspeed.
PUTTING THEORY TO USE
Now let’s see how we can use this theoretical knowledge to improve the possibility of making a successful dead-stick landing. With the loss of the engine, you are left with only the two forms of energy: kinetic energy and potential energy. It’s obvious that it’s better to lose an engine with the airplane high and fast rather than low and slow. But no matter where you are when the engine quits, it’s important to transition to the best glide speed for your particular airplane: If you’re going fast, enter a shallow climb and trade airspeed for more altitude; if you are flying slow, transition into a shallow descent to obtain the best glide speed.
Now it’s time to determine if you can make it back to the landing runway, and in this situation, there are only two possibilities: you can’t make it to the runway or you can.
IF THE RUNWAY ISN’T AVAILABLE
If it’s not possible to make it back to the landing runway, there are a few things to consider: finding a smooth surface to land on, landing into the wind, and making a gear-up landing.
Plan to land on the smoothest possible surface. If you are at your home field, you should be familiar with the terrain and know the best place to make this forced landing. If flying at another field, look over the surrounding area before you fly to get familiar
with the best alternate landing site.
Always plan to land into the wind—even if that means turning the airplane away from you. It’s important to have the slowest possible ground speed when landing in unprepared terrain, which means landing into the wind.
For example, if the wind is blowing at 10mph and your plane glides at 20mph, you will have a landing speed of 30mph if landing with the wind but only 10mph if landing into the wind.
If your airplane is equipped with retracts, consider making a gear-up landing if you are forced to land on grass or other unpaved surface. Extended landing gear stand a good chance of being damaged with a rough landing, possibly causing massive structural damage. Making a gear-up landing will enable the airplane to skid on the ground to dissipate energy and increase the possibility of keeping the gear and gear doors intact.
IF THE RUNWAY IS NEARBY
Now let’s assume you had an engine failure in a position where you have enough energy to make it back to the runway. You may think you have it made, but there are still dangers to overcome to get the plane safely on the ground.
If you are high enough, fly the plane to a position over the runway and spiral down from there. This will put you in a position where you are guaranteed to have enough total energy to make a successful landing.
If you make the decision to fly a wide landing pattern, however, there is always the possibility that two bad things can happen.
The first problem it that flying a wide deadstick pattern requires more judgment to evaluate the plane’s total energy. If the pattern is too wide or the headwind is greater than you anticipated, the plane will not have the energy needed to make it back to the runway. In this case, you have taken the plane from a position where it had enough energy to land to a position where that energy was wasted and you can no longer make it to the runway. To keep this from happening, do not configure to the landing configuration until you are sure you have the runway made; once you’ve done that, the gear and flaps can be extended, as needed, to dissipate excess energy.
The second problem with flying a wide pattern is that you may actually come down on final with too much energy. It’s hard to imagine that too much energy would be a problem, but how many times have we seen a dead-stick landing come over the approach end of the runway with too much airspeed? The plane is now flying down the runway trying to dissipate this excess airspeed, and it finally makes a long landing, only to run off the end of the runway.
If you find yourself in this position of having too much energy (airspeed) on final, there are a few things you can do the help the situation:
Extend more flaps if they are available. You may be making a no-flap landing or a half-flap landing. In this case, you can go to full flaps for additional drag. Normally, the first half of flap extension will give you additional lift with only a slight increase in drag, while the second half of flap extension will provide only a slight increase in lift but a great increase in drag. Therefore, full flaps should be avoided until the landing is assured.
Rather than fly a straight “normal” final approach, weave the airplane right and left. This will extend the flying distance of the plane, allowing more time to dissipate airspeed. n Slip the plane by applying rudder in one direction and ailerons in the opposite direction. This will cause the plane to fly sideways, which will increase the drag as the wind hits the side of the plane. n Rather than fly a normal glide-path angle, dive the plane to a point short of the runway. Notice that I said “short of the runway.” This is because the plane will increase in speed as you dive, which will also increase the overall drag on the plane. This excessive drag will be used to dissipate the excess energy. This maneuver will put you in a position short of the runway where you can make a more normal approach and landing, keeping the plane from overshooting the runway.
PRACTICE MAKES PERFECT
One of my favorite things to remember are the “five Ps”: Proper planning prevents poor performance. In the case of dead-stick landings, this means to practice them (with the engine at idle) just as you would practice any other maneuver. Start with the plane over the runway at an altitude of 100 feet or more. Bring the engine to idle, but keep the gear and flaps up and make a 360-degree turn to final and see if you can land from the approach. Now, fly the same pattern but, this time, with the gear and flaps in the landing configuration. How did the gear and flaps change the pattern? Practicing such patterns, at varying altitudes, should give you a good idea of the glide characteristics of your plane, which you can use to fly simulated engine failure patterns from other positions. With a little practice, you will be able to bring your plane to a safe final approach from almost any flying position, providing you have the total energy needed to get back to the runway.