Help for CFI Tools Weight & Balance

 

 

PURPOSE: The Weight & Balance App is used to perform weight & balance calculations in a flexible format that is easy to use and customize.

 

There is no limit on the number of airplanes that can be created in this W&B App.

There is no limit on the number of Stations defined for each airplane.

There is no limit on the number of Envelopes defined for each airplane.

 

CAUTION! Please consult your Pilot's Operating Handbook or Approved Flight Manual for complete, accurate Weight & Balance Information for your airplane. The numbers for every airplane are unique, some samples are used in the App but they do not have the correct values for your individual airplane.

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When to Use the Weight & Balance App

To calculate the Weight and Balance for your airplane

It's a lot easier than doing it by hand. And once you have it setup for your airplane it is easy to make copies so you can save different configurations such as different fuel or passenger loads.

To calculate the Weight and Balance for many configurations of your airplane

Since there is no limit on the number of airplanes or stations you can make many copies of your airplane. You might have one with full fuel and 2 people and another with half fuel and 4 four people or any other configuration that you want to save.

To email your Weight and Balance straight from the App using standard email

Just press the Email button and the W&B report email comes up ready to send as an email attachment.

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Main Screen

Airplane

Touch the button at the top of the screen to select an airplane. The App comes with a number of sample template airplanes. It is unlikely that any of these will match your airplane. Your airplane is unique! You must enter the numbers from your AFM/POH in order to get an accurate calculation. These templates are really fairly simple and even if you can't find one that matches your airplane almost any of them can be quickly customized to match your numbers.

 

Stations

- Here is a list of the Stations defined for this airplane. Touch a Station on this list to go to the Station update screen for the selected station.

Touch the New button to create a new Station.

Touch the Sort button to move the Stations around and change their display order.

 

The Envelope Drawing

- This graph shows the answer. The center of gravity (CG) is plotted along with the weight. If this point is outside any of the defined envelopes this will be noted on the graph.

 

Airplane General information fields

These fields are used to enter identifying information about your airplane. Max Gross is only used to calculate the Excess Capacity, it is not used for the CG calculation. Enter the Max Gross for the airplane in this field.

 

Summary

The fields in the Summary are output from the calculation.

Total Weight is the sum of the weights entered for the Stations.

Excess Cap. is the difference between Max Gross and Total Weight. This is a nice number to know it is basically how much more weight you can put in the plane without going over Max Gross.

No Fuel Weight is the Total Weight minus the sum of the Stations identified as fuel.

CG is the calculated Center of Gravity.

No Fuel CG is the calculated Center of Gravity with all the fuel stations weight set to zero.

 

Envelopes

- These are the Envelopes for the airplane. There is no limit on the number of envelopes for an airplane. Most of these planes have a normal and utility envelope defined. You may also see a third envelope defined for airplanes that have a Max Landing Weight. Any other envelope that makes sense for your airplane can be defined.

 

Touch an Envelope name to select the Envelope.

Touch the New button to create a new Envelope.

Touch the Update button to update the selected Envelope.

Touch the Delete button to delete the selected Envelope.

Touch the Up or Down button to move the selected Envelope on the list. This changes the order in which they are displayed.

 

Use the New Airplane button to create a new airplane.

Use the Delete button to delete the currently displayed airplane.

Use the Copy button to make a copy of the currently displayed airplane.

 

 

Share Button

- The Weight & Balance definitions for any or all of your airplanes can be shared with other General Aviation App users.

Touch the Share button to share the W&B Airplane definition.

 On the Share screen select the airplanes you would like to share and touch the Share button.

The next screen you see will be the standard Android Sharing screen and the options presented may vary depending on the configuration of your device. Every option will not work on every device, but Email is one option that should be standard on most devices and works well as a method to share the definitions.

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How to Use the Weight & Balance App

View W&B Information

- Touch the grey Aircraft button at the top of the screen to select an aircraft

- View the W&B information

 

CG Calculation Method

- Select the Distance or Weight-Moment method, see below for details

 

View & Update W&B Stations

- View the Aircraft

- Touch the Station that you would like to change

 This will bring up the individual Station update screen

 

View and update the Station

Station Fields:

Station: This is the name of the Station

Weight: The weight at this station

MmT/CG Loc: This is the Moment or CG location.

If the airplane used the Distance method this is the CG Loc usually measured in inches or millimeters.

If the Weight-Moment method is used this is the Moment found on the POH graph, this is usually expressed in Inch-Pounds or Kg-m.

Weight per Unit: If Enter Units? is selected (see below) this field should contain the weight of a single unit, for example if this is fuel the weight of one gallon of fuel (6 Lbs.) may be entered here

Units: If "Enter Units?" is selected (see below) this field should contain the number of units for example 53 gallons of fuel.

Fuel?: This switch is used to indicate that this station is for fuel. This is used to calculate the second CG which is for zero fuel. Any station that has a Station name that contains the word "Fuel" will also be counted as fuel for this zero-fuel calculation.

Enter Units?: This switch is used to indicate how the weight for this station is calculated. If this switch is set to "No" then the weight is simply entered in the Weight field. If this switch is set to "Yes" the weight is calculated by multiplying "Weight per Unit" by "Units". This switch was created to make it easier to enter the weight for fuel. Many people like to deal with Gallons or Liters rather than Pounds or Kilograms. This switch allows you to do that.

 

View & Update W&B Envelope

- View the Aircraft

- Touch the Envelope that you would like to change and Touch Update

- View and update Envelope

The table on the right side of this screen shows the definitions for each point in the envelope.

There are two numbers to define each point. The first number is a weight, the second depends on the Compute Method chosen for the airplane.

If you choose the Distance method the second column will contain the distance for that point in the envelope usually defined in inches or millimeters. If you choose the Weight-Moment method this number will be the Weight-Moment usually defined in inch-pounds or Kg-m.

 

A note about the unit of measurement

This W&B App does not use any particular unit of measurement. There is no need to specify this unit as long as the user in consistent in entering data. For example if you decide to use pounds rather than kilograms for weight measurement this OK as long as all the weights entered are expressed in pounds. This consistency only has to be maintained within a specific airplane. That means you can have one airplane that records weight in pounds and another that records weight in kilograms.

 

Delete a Station

- Touch the Station and you will see the Station edit screen

- To Delete Touch the Delete this Station button

 

Delete an Airplane:

- Touch the Delete button

- Confirm the Delete

 

Add an Airplane:

- Touch the New Airplane Button

- Update the information provided in the template to match your airplane

- You may find it easier to copy an existing plane using the Copy button.

 

The calculated CG is plotted on the graph as a Red Dot. A second CG that represents the zero fuel CG is also plotted as a Red Dot.

 

The two Red Dots represent the starting and ending CG's and the difference between them is the weight of the used fuel.

 

The weight of the fuel is identified as the weight of the Station whose name contains the word "fuel". And any Station that has the "Fuel ?" switch set to the "Yes" position.

 

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Email

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The Email function allows you to email the W&B report. This function is useful for dispatchers who have to collect W&B information for a fleet.

 

Just touch the Email button and fill in the destination. It's ready to go.

 

This uses the standard Email screen so you can use any standard email functions.

 


 

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Please Note!

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There are 2 types of Calculation/Plotting Methods Supported:

 

Distance and Weight-Moment

 

The method you choose depends largely on the Center of Gravity limits table that you have in your POH. Different manufacturers supply these numbers in different formats.

 

Choose the Distance method if your graph has a distance along the bottom or top of the graph usually expressed as inches or millimeters.

 

Choose the Weight-Moment method if your graph has a weight-moment along the bottom or top of the graph usually expressed as inch-pounds or Kilogram-millimeters.

 

Distance Method

This method uses the CG envelope that shows a distance along the bottom of the graph. For this type aircraft "Plot Type" should be set to Distance. The Stations should be entered with Weight and Location/Distance from the datum.

 

The Moment is calculated for each Station like this:

Moment = Weight x Location

 

The CG for the airplane is calculated like this:

CG = Total Moment / Total Weight (expressed in Inches or Millimeters)

 

Weight-Moment Method

This method uses the CG envelope that shows a weight-moment along the bottom of the graph. The Stations should be entered with Weight and Location/Distance from the datum.

 

The Moment is calculated for each Station like this:

Moment = Weight x Location

 

The CG for the airplane is calculated like this:

CG = Total Moment (expressed in Kg-m or In-Lbs)

 

Although they both do the same thing, there are two key differences in these methods.

The unit of measurement for the CG is different. The difference is simply that in the Weight-Moment method the CG is not divided by the weight.

And using the Weight-Moment method the answer is usually expressed as a number in the thousands as opposed to the Distance method where the CG answer is usually expressed as dozens when using inches. This can lead to some confusion if the W-L chart in your POH displays the scale along the bottom row as In-Lbs / 1,000. It is easy to forget to divide or multiply by 1,000 depending on which way you are reading the chart.


 

Weight & Balance Initial Screenshot

 


Weight & Balance Envelope Screenshot

 


Weight & Balance Sharing Screenshots

 


 

Weight & Balance Station Update Screenshot

 

 


 

Weight & Balance Create Email Screenshot

 


Weight & Balance Email Attachment Sample

 

 

   Weight and Balance Report Sat 2011-01-29 11:16 EST

 

Registration: N3504L

        Make: Cessna

       Model: 172-S

 

             Station     Weight        Loc     Moment

 

         Basic Empty     1714.2     40.757    69865.6

          Front Left        180         37     6660.0

         Front Right        200         37     7400.0

           Rear Seat          5         73      365.0

           Baggage 1          5         95      475.0

           Baggage 2          0        123        0.0

                Fuel        210         48    10080.0

 

               Total       2314                 94846

 

      Max Gross: 2550

Excess Capacity:  235

 

             CG:  41.0

     CG No Fuel:  40.3