Glider Weighing and Balance Program


(C) Copyright 2002-2011 by Paul R. Jorgenson KE7HR

GlideWeigh is a program designed to assist the owners of single seat gliders. GlideWeigh simplifies the task of generating data and a report for weight and balance purposes.

There are eight variables that need to be entered into the program during the actual weighing - Main Gear Weight, Main Gear Arm, Tailwheel Weight, Tailwheel Arm, Maximum Gross Weight, Forward CG Limit, Aft CG Limit, and Pilot Seat Arm. Weights should be entered as pounds and Arms should be entered as inches. When everything is entered, press the calculate button to generate the Empty Weight, Empty Moment, Empty CG, Minimum Pilot Weight (at what CG), and the Maximum Pilot Weight (at what CG).

There are additional spaces on the form for the entry of the Sailplane type, Builder, Serial Number, N Number, Signature, Certificate Number of signer, and the Date that the task was accomplished. When the report is complete, the form can be printed out on the attached printer. Keep the report with the glider log books and also use the Pilot Weight information to update the required placards in the glider.

The actual weighing procedure should be outlined in your Pilot Operating Handbook (POH) or homebuilt plans instructions. The Maximum Gross Weight, CG limits, and Pilot Seat Arm will also be found in these reference materials. The only exception to this may be the Pilot Seat Arm on homebuilt aircraft. Since each homebuilt is unique, your seat location (and thus the CG of the Pilot) will be different from all others. Consult the plans and instructions for specific information about how to determine this data.

The general procedure for weighing an aircraft (don't forget to get SPECIFIC instructions from your authoritative source!) are to (1) level the aircraft (2) find the Arm (distance from the Datum) to the Main Gear and the Tailwheel (3) get the weight for both the Main Gear and Tailwheel. The Datum is described in your aircraft POH or instructions. Some gliders (Schweizer 1-35 for example) use a fuselage former in the nose as the Zero Datum while others (like the homebuilt BG12 series) use the leading edge of the wing. The Datum line runs 90 degrees to the longitudinal (nose to tail) axis of the glider. Plumb bobs are often used to extend the Datum Line to the floor where it is marked. Using a good square, measurements for the Main Gear and Tailwheel are taken from this Zero line. Care must be exercised to insure that the measurement to the gear is square (90 degrees) to the Datum line. A few inches of inaccuracy make a big difference in the numbers and hence, the performance and safety of your flying machine.

With the distances to the gear and the weights of each in hand, the program makes quick work of calculating the required aircraft and pilot data. Remember that the minimum and maximum pilot weights generally occur with the CG at the extreme ends of the allowable range. Flying at the extreme ends of the allowable CG range is, in my opinion, playing with the controllability and stability of your ship. Calculating ballast to get the CG to be nearer the center of the allowable range, while still staying within the Gross Weight limitations is suggested. (For you BG12 pilots, have a look at the program BG12WB available elsewhere on this web site.)

Remember that this program is only a calculator, a tool to be used. While I believe that it functions properly and gives good answers for good input, there may be errors. Check any critical to flight safety information with another source or method before staking your life on it.

The screen shot below shows the information for my BG 12/16. Your information will, of course, be quite different.

GlideWeigh can be downloaded from my web site by clicking the highlighted word. File size: 48 Kb.

This is a Visual Basic 6.0 program that runs under Windows 95 on up. Most computers will have the auxiliary files to run this program. If there is a need for other files by users (xxx.dll) let me know and I will upload them to the web where they can be downloaded or I can email them to you.

WARNING LARGE FILE! 1.8 Mb can be download zip file from my web site by clicking the highlighted words. This is the full install program.

If you like this program, send me an email. Send me an email even if you don't like it and tell me why. If you find this program useful and educational, consider sending a donation of $10 to encourage me to do more glider programing (or at least buy me a beer).

You can email me at ke7hr at
Replace the 'at' with the @. It is my attempt to foil the spam email robots.

Created 8 April 2002.
Updated 18 November 2011
(C) Copyright 2002-2011 by Paul R. Jorgenson
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