Hello, I was intersted to know what was the fastest plane currently known, (non prototype or classified tech), so, according to wikipedia, the SR-71 Blackbird has a record of 3,529.6 km/h wich is 2,193.2 mp/h or 980.44 ms. Here is my attempt: The SR-71: With the crew: For my experiment, having very little fuel, I decided to build a cargo ship and lock the plane on top of it: All was surplisingly stable and flyable: Getting above the 8km step and preparing to decouple: Decoupling, everything nominal: And record is broke! 1101.5ms, 3965.4 km/h !!! With this design going above 1102 was impossible for me, the time to get there the overheating is almost at maximum for the cockpit, and the speed start to drop also. After, I tried to get back to ksp but not enough fuel, time for a soft landing in water : At least the crew survived ^^ That's all! If you manage to break the record, let me know !