RC Model Aircraft Center of Gravity Calculator v3.0 (replaces v1.x and v2.x)
Note 1: Potentially not compatible with some versions of Android 5.x (Lollipop) yet, please try it out to be sure, this is due to some custom versions of Android having problems with screen compatibility mode. This has been fixed in Android v5.1.1 r6.
Note 2: please email if you have a problem or suggestion
Note 3: This app was built with MIT App Inventor, the permissions* (see below) required are the defaults, I have no control over what permissions Google/MIT App Inventor requires an app to have. This app has been published on Google Play since 2012 and since it is still here you can be assured that Google Play has no problems with it.
Note 4: Please see also my RC-E Calculator which includes wing loading, flight time, prop thrust and other calculators:
► RC E Calc Pro
This may prevent your plane from crashing! It has been said "A nose-heavy airplane may not fly well, but a tail-heavy airplane may fly only once."
This app will calculate the POSITION of the Center of Gravity (CG or CoG or Balance Point) measured back from the leading edge at the wing root in the units of your choice.
Enter your measurements for:
- tip chord length,
- root chord length,
- sweep length and
- required CG percentage (eg 28%)
of your model airplane and then the CG, wing area, geometric mean chord and tip-to-root chord ratio will be calculated automatically.
You can use inches or centimeters and the result will be in the units you used (don't mix units though).
A too rearward CG position can cause unrecoverable (potentially fatal) instability!
25-35% recommended for most conventional wings, 12-18% for pure flying wings, 15-19% for Delta wings.
This calculator uses the Neutral Point, the AIRCRAFT'S aerodynamic center (AC), as a reference point to calculate the CG range. It uses a simple but fairly reliable method of determining the CG of a model aircraft.
Thanks for downloading and comments welcome.
- improved layout
- improved images
- new instruction page
- corrected wording
- Resize & refit for tablets
- Refit text flow for large numbers
- Center everything
- Minor layout improvement & bug fixes
Version 2.0+: implemented due to Google licensing changes.
- No longer requires a button tap to calculate, calculates automatically after the all the fields are filled.
- Added wing Area calculation
- Changed layout for ease of use/visibility
- Fixed small bugs
(*This app requires the following default MIT App Inventor permissions:
android.permission.INTERNET - to check for updates and so that the screen's background image property can be set to the URL of an image on the web if there is a background image
android.permission.WRITE_EXTERNAL_STORAGE - to move the app to EXT SD on your phone if necessary.
android.permission.READ_PHONE_STATE - to check for incoming phone calls and then hide the app if necessary.
android.permission.READ_EXTERNAL_STORAGE - access the app on EXT SD if necessary.)
- Rebuilt with MIT App Inventor 2 (AI2)
- Corrected font sizes
- Layout changes
- Improved text and instructions