The following list explains common questions received by technical support about creating or editing aircraft models:
Leaving necessary performance fields blank — The program cannot identify the difference between leaving data out and adding a zero. Any spaces that are left empty are assumed to have a value of zero; the program calculates on that zero, causing an error in calculation.
Not completing the envelope in the Weight & Balance tab — If the envelope does not appear gray, it is not seen by the program as a closed envelope. The program cannot be certain if you are inside or outside.
Not entering any weight and balance information — Even if you are only using the program for performance, if the weight and balance data is incorrect, it can affect the performance numbers. Basic models assume performance based on weight; thus, if the weight is incorrect, the model cannot be accurate.
Mistakes made in the performance information — Often a model appears to work correctly except at a certain altitude or weight. This situation is usually the result of a mistake, such as entering 1227 instead of 127 for a speed in a single field. The program averages and interpolates information so that it is accurate at speeds and weights between the entered data. One error can affect any calculation near the data.
In the Basic Info tab, not matching the fuel capacity with the information under the Weight & Balance tab — The two tabs should indicate the same quantity of fuel, even if one is in gallons and the other is in pounds.
Not specifying that the fuel stations are type 'Fuel' in the Weight & Balance section — This situation results when the program does not allow you to enter fuel when clicking Preflight > Weight & Balance for route. If you make the change, and the fuel in the Navlog does not change or shows zero fuel, this problem might be the cause.
Entering Moment instead of CG for performance — If the envelope is narrow and angular, it is probably not a CG envelope.
Trying to create a Constant Power model when the POH is configured for a Constant Altitude model, or vice versa — In this situation, there is no correct way to complete the model and get satisfactory performance. Either one can be a good basic model, but the data will not support more complex types unless the POH is written for it.
Entering fuel as one unit, although the fuel is identified as a different unit in the Aircraft Setup Information tab — If the Aircraft Setup Information tab has the units for fuel, speed, and so on, set as one type of unit, the performance tabs and Basic Info tab must use the same units. Weight and balance are the only exceptions: they are always in weight units, never in liquid measure.
Entering too little data for a configuration — The program is set up for groups of three. Any weight, altitude, power setting, and so on, needs at least three entries to average correctly. If too little data is entered, the program does not let you plan with the model.
Not entering +20 and -20 information for Constant Power and Constant Altitude models — Even if you only want to assume standard conditions, the program registers the missing lines as zeros and assumes it is valid data.
Leaving the Climb & Descent information blank in the Basic Information tab — If this information is left at zero, the program assumes it is valid data and plans with it.