| Tail Number / N-Number | N21SX |
| Manufacturer | LUEBKE RALPH C |
| Model | STD CLS AMER SPIRIT |
| Year Built | 1993 |
| Manufacturer's Serial Number | 11 |
| Aircraft Type | Glider |
| Category | Land |
| Builder Certification | Not Type Certificated |
| Number of Seats | 1 seat |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | NONE |
| Engine Model | NONE |
| Number of Engines | 0 engines |
| Type of Registrant | Individual |
| Owner Name | CANTWELL PAUL M |
| Street | 12356 E METCALF AVE |
| City | MOMENCE |
| State | IL |
| Zip Code | 60954-3231 |
| Region | Great Lakes |
| County | Kankakee County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Experimental |
| Airworthiness Date | 1999-04-16 |
| Certificate Issue Date | 2018-09-04 |
| Last Action Date | 2021-08-13 |
| Expiration Date | 2028-09-30 |
| Status | Valid Registration |
| Mode S Code | 50334317 |
| Mode S Code Hex | A1B8CF |