| McDonnell PJ40 | |
|---|---|
 XPJ40-MD-2 on Katydid target drone | |
| Type | Pulsejet |
| National origin | United States |
| Manufacturer | McDonnell Aircraft |
| First run | 1942 |
| Major applications | McDonnell TD2D Katydid |
The McDonnell PJ40 was a pulsejet engine built by McDonnell Aircraft during the mid 1940s.