| Tail Number / N-Number | N3121H |
| Manufacturer | ENGINEERING & RESEARCH |
| Model | ERCOUPE 415-C |
| Year Built | 1946 |
| Manufacturer's Serial Number | 3746 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 2 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | CONT MOTOR |
| Engine Model | C85 SERIES |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 85 hp (63 kW) |
| Average Cruising Speed | 90 miles per hour |
| Type of Registrant | Individual |
| Owner Name | ARNOLD THOMAS J |
| Street | RR 3 BOX 18 |
| City | HOOKER |
| State | OK |
| Zip Code | 73945 |
| Region | Southwestern |
| County | Texas County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1957-05-27 |
| Certificate Issue Date | 2004-04-20 |
| Last Action Date | 2022-12-14 |
| Expiration Date | 2030-03-31 |
| Status | Valid Registration |
| Mode S Code | 50650302 |
| Mode S Code Hex | A350C2 |