Sonex Weight & Balance

Finishing your plane and getting ready for a weight & balance? It’s easy with the power of Microsoft Excel.

Link to W&B Excel Calculator

There is a great video on Sonex Videos which I highly recommend. These videos made W&B easy, but being a computer geek, I wanted to eliminate the need for paper and also wanted an online way to have my W&B calculate with me at all times. Thus, the creation of the Excel W&B Calculator.

After watching the videos, it was time to take the plumb line to the plane per the video and get my measurements. I made it simple by measuring everything and using duct tape on the floor to mark my spots for each reference line. Then using a tape measure, I was able to get the exact measurements and plug into my “Excel Calculator”.

Here is the front wheel. I noted the duct tape with FW for “front wheel”.

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After creating all of the markings, I entered them into the first tab on the Excel spreadsheet “W&B_Master” in the cells E12:E14 and L13:L17 (highlighted in yellow). This will be used throughout the workbook.

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You are required to do an Empty W&B, Forward, Aft and First Flight. Additionally, you will want a working model for every day use which I will talk about later in this blog.

Now it is time to weigh the plane with aircraft scales. Just like a boat, the best kind is not your own boat, but a friend with one! Borrowing a friends scales, with an empty plane (no fuel), set them to zero and then roll the plane on!

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Look how sexy. :). Now record the weights at each wheel. Here is the left main gear for example.

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Enter those into cells D12:D14 (highlighted in grey).

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Now you can put in the other variables to complete the puzzle and see how your W&B will be! Be sure to only type into the grey cells to adjust weights.

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The second tab of the worksheet is used as my daily W&B calculator depending on my flight for the day.

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I have formulas written to warn the pilot if you exceed gross weight, forward or aft CG! See below how the weight limit is exceed by 72lb with a 190 passenger.

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Or if the CG is off due to fuel or baggage loading. Note the issue is in baggage. Although the Sonex doesn’t hold that weight, I wanted to demonstrate the safety feature within the spreadsheet.

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I hope you enjoy the spreadsheet! Stay tuned for my next blog will be about Vx and Vy using Excel.

Disclaimer: The safety of flying is the sole responsibility of the pilot and any advise or use of my spreadsheets, tips, tricks or anything else is at your own risk. 🙂

Now you are ready for a Happy First Flight!

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