Upper stage.
Upper Stage consisting of 4 x Aerobee Engines used on early orbiters.
| Name | Engine | Flight dates | Success | Failed | Destinations | |||
|---|---|---|---|---|---|---|---|---|
| First | Last | Stage | Lower | Mission | EO | |||
| Spruance | Aerobee | 1952-01-06 | 1952-05-02 | 2 | 2 | 2 | 1 | 7 |
| Spruance Stage | XASR-1 | 1952-01-06 | 1952-05-02 | 2 | 2 | 2 | 1 | 7 |
| Name | Date | LV | Payload | Destination | Result |
|---|---|---|---|---|---|
| Midway Yorktown 0-1 | 1952-01-06 | Midway-I | Yorktown 0-1 | Low earth orbit | Stage 2 Failure |
| Midway Yorktown 0-2 | 1952-01-26 | Midway-I | Yorktown 0-2 | Low earth orbit | Stage 1 Failure |
| Midway Yorktown 1 | 1952-02-16 | Midway-I | Yorktown 1 | Low earth orbit | Success |
| Midway Yorktown 0-3 | 1952-03-07 | Midway-I | Yorktown 0-3 | Low earth orbit | Stage 3 Failure |
| Midway Yorktown 2 | 1952-03-29 | Midway-I | Yorktown 2 | Low earth orbit | Mission Failure |
| Midway Yorktown 0-4 | 1952-04-14 | Midway-I | Yorktown 3 | Low earth orbit | Stage 3 Failure |
| Midway Yorktown 3 | 1952-05-02 | Midway-I | Yorktown 3 | Low earth orbit | Success |