Most aircraft accidents occur during the takeoff or landing phase of the flight. Collisions with obstacles during climb out, runway overruns on landing do occur every now and then. In this section of the site we will take a look at the various factors contributing to the performance of the aircraft in this part of the flight.
There are a number of speeds defined for aircraft where it has a certain predictable performance. These are: best rate of climb speed and best angle of climb speed. Both are used by the pilot to reach an altitude in the minimum amount of time or distance traveled.
The climb performance of an aircraft is influenced by factors like: the amount of applied power, type of propeller, airspeed, drag in the form of flaps or landing gear and weight. We are going to examine these factors to show you the effects they have.
This can be measured as the climb angle (VX) or the rate of climb (VY) speeds and due to certain factors, although these speeds will remain more or less the same, the result (climb rate or angle) will change. At the service ceiling of the aircraft (VX) and (VY) will practically coincide at the same speed.
Varying the amount of power used during the climb over the power required directly results in a different climb performance. If your aircraft is not climbing as expected, check if full power (or recommended climb power) is set or anything else is producing drag (flaps, spoilers, etc).
Flying with a higher or lower airspeed (than normally used for best climb angle or rate) will result in a lower climb performance compared to the optimum speeds from the POH for your aircraft.
A heavier aircraft decreases the climb performance as the power required to maintain a given speed in level flight increases with a higher all up weight. With the same engine but higher weight, there is less excess power available to climb. And as a result, climb performance and service ceiling will suffer.
Extending the flaps will decrease the climb performance as lift/drag (L/D) ratio is reduced and the power required increased. The best rate-of-climb and angle-of-climb speeds are always reached with flaps up. Hence the need to retract flaps after a go-around if there are any obstacles in the climb out path. Some aircraft are not able to climb if full flaps are selected due to the amount of drag they create.
For example: a C-172 with full flaps will not climb like a homesick angel during a full power go-around.
Some aircraft manufacturers recommend a certain takeoff setting for flaps during a short field or high performance takeoff. Although L/D ratio will suffer and drag is increased by the flaps it will permit the aircraft to fly off the runway sooner, but the climb out performance will be somewhat less.
Aircraft with retractable gear should retract them as soon as no more usable runway is available and a positive rate of climb is established. The drag caused by the gear obviously reduces climb performance. Aircraft with a fixed gear have no choice in retracting but to have the gear as much as streamlined by fairings and wheel pants as possible. Have a look at Lancair and Pipistrel aircraft for some good examples of those applications.
Just remember to not to prolong the climb at the maximum angle of climb speed as this speed is relatively slow, engine cooling is poor and overheating and detonation could be the result. Lower the nose and increase the airspeed as soon as possible after clearing the obstacles to enhance cooling and forward view. Maintain your airspeed at cruise climb speeds.
This property consist of air temperature, altitude and these are influenced by ambient pressure and humidity. Any change in one of these factors changes the density altitude and consequently the climb performance of any aircraft.
An increase in altitude reduces air density and as a result there will be a decrease in engine power and wing and propeller (airframe) performance. The amount of power available reduces with altitude, unless the engine is turbo- or supercharged. Power required goes up with altitude and at one point these two will be the same. The aircraft then has reached its absolute altitude. The definition of service ceiling is where the aircraft vertical speed is reduced to 100 ft/min or less.
These two have a direct effect on air density and thus climb performance. At any altitude where OAT is higher than standard ISA temperature climb performance will be reduced. If QNH, ambient pressure, is lower than ISA then aircraft climb performance is affected too.
Any change in the aircraft attitude due to maneuvering, turbulence and turning reduces the climb performance somewhat as part of the excess power is needed to compensate for the maneuvers.
With exactly the same power settings and climb speeds, the result with a headwind will be that the distance traveled over the ground is reduced, whereas with a tailwind the distance over the ground is increased. It can be seen that climbing into the wind has an distinct advantage when obstacles are in the climb out path. With a headwind the climb angle is greater at the same climb speed.
Written by EAI.
Experimental Aircraft Info
