There are quite a bit of factors that can affect aircraft performance. If you don't keep in mind these factors you may find yourself in a dangerous situation where you will receive a violation from the FAA or even worse, dead. Aircraft manufacturers provide this information in the form of charts. These are generally located in the Performance section of the POH. Performance charts are usually shown as a table or graph. To get the most accurate result you must use all the chart procedures and guidelines.
Two factors affecting airplanes are the weight of the airplane and wind. The groundspeed and time en route can change due to the wind direction and speed. Since we know that performance decreases with altitude we also know that decreases in air density due to temperature, pressure, or humidity will also cause a decrease in performance. Humidity is usually disregarded due to the maximum affect only being a 7% decrease.
Another large reason to determine performance is landing and taking off distance. This can make the difference between hitting an obstacle or rolling of a runway. The runway gradient is the amount of change in the slope of a runway over its length. A gradient of 2% means the slope changes 2ft for every 100ft of runway. A positive gradient may be favorable for landing as it will require less room to slow down, but it also makes it unfavorable to take off due to increased force required to push the airplane up the slope. Takeoff and landing charts for each specific airplane help tremendously with calculating these numbers.
 |
| An example of a takeoff distance chart from a CESSNA POH book |
The best angle of climb airspeed is normally used for obstacle clearance immediately after takeoff. Due to a higher pitch attitude your forward visibility is also decreased. Usually you use the best rate of climb after clearing all obstructions. This will give you the highest climb rate. Before an airplane can gain altitude it must have a reserve of thrust. The service ceiling of an aircraft refers to the altitude where an aircraft is only able to climb 100 feet per minute. This is commonly referred to as absolute ceiling since it represents the practical ceiling for the aircraft.
0 comments:
Post a Comment