Why Don’t They Launch Rockets From Aircraft?

There is an error in the graphic with the 747 which accidentally still shows the weight in pounds as 172,000 pounds instead of the 904,000 pounds its supposed to be. 410,000 KG is correct though. It was accidentally carried over from the previous graphic from the 737.

17:01 "Liftoff! Disregard." A classic line.

This was my senior design project in the last semester of my aerospace engineering undergrad. We were tasked with designing an air-to-orbit rocket that would be launched from a modified U-2 (which we reverse-engineered the previous semester) carrying a payload to low Earth orbit. We were given full control over the parameters of the rocket, launch altitude, launch site and direction, with a focus on comparing how beneficial altitude delta was to the performance gains of launching at higher initial velocities. Our team was split into various disciplines (Performance, Aerodynamics, Structures, Controls, etc.) so we all had to work in tandem, cross-sharing data. Performance was my area. I used data and telemetry from other existing vehicles, like Orbital ATK's Pegasus, to validate my results. In the end, we established that air-launching definitely allowed for a performance gain, but the gains were obviously not linear with increasing altitude. There's a point where flying higher and higher wasn't really worthwhile. More importantly, though, we learned that initial velocity is where the true performance gains were at. Launch a rocket from a hypersonic platform and altitude is almost irrelevant. Now spend the next hour destroying your brain cells on all the reasons that such a feat would be nearly impossible...especially if you want your rocket to carry any kind of meaningful payload into LEO. [LOL]

I started this video like, "YEHH!?? WHY DON'T WE AIR LAUNCH??" and ended like "oh that's why" Thanks buddy, good work o7

A couple more points you missed: 1) The ability to launch from anywhere is massively hamstrung by needing to meet all of the licensing and regulations for each and every new area. Launching from a fixed pad allows the red tape to be a lot more easily handled. 2) The small launch segment is basically dead, thanks to the likes of the Transporter missions. Companies like Rocket Lab, Relativity, and Firefly all see the writing on the wall and are pivoting to medium lift, but there's just no way for Virgin to do that with an air launch system.

After watching from your orange flight suit days, i can still say that every single video you put out is worth getting excited about. I cant tell you how much your content is appreciated and needed, especially for people that dont just watch rocket stuff everyday.

I worked on Pegasus in the 1990’s. We had a couple of stage separation issues early in the program but we solved those. Fun times.

Great Video Tim. I love the way you make things easy to understand for all. So glad I was able to meet you in Austin. That was a fantastic weekend. I hope to do it again next year.

One thing to add is that the Isp advantage would only be for the first stage, as later stages already operate in vacuum. And Isp is relatively unimportant on the first stage, since staging velocity is not very high. This is especially the case if you want to recover the first stage, as Falcon 9 does (and if you do propulsive landing, those engines have to operate at sea level or close to it.)

hey tim i am 12 yr old from india, bangalore i have always loved your videos and they have taught me alot, thanks for fueling me to become an aspiring astronaut

Thank you, Tim (all everyone behind the scenes)!!! These videos are fantastic - Go Team Space!!!

The air-fed booster engine concept at least removes sensitive biological components from the equation. To cut down on complexity from a turbine engine, just use fuel injected into aerodynamic pressure fed scramjet. They wouldn't work at launch time but you could throttle down or discard the launch engines and still get decent thrust once you are moving a few hundred m/s through the atmosphere. Appreciate it Tim. Great work as always.

Why don't they fly the booster and starship to their pads on their own power instead of moving them down the street ;D

Because the flamey end is pointed the wrong way! Duh

Great video! I remember a 1980s air launch concept drawing with a Space Shuttle Main Engine mounted in the tail of the 747 carrier aircraft, to get extra boost and trajectory. Cool in concept, prohibitive in practicality and economics.

Thanks so much for creating and sharing this informative and timely video. Great job. Keep it up.

Per the Pizza Analogy... Colin Furze recently made that work quite well... we just need to get him to make an Air Launch system. Then it would work great and be a huge advantage... LOL! 🤣 Love the video Tim and how well you can make these complex concepts easy to understand. Keep up the great work!

Variable geometry intake and nozzle would probably be my big gamble. One engine that transitions from ram jet, to scram jet, to pure rocket. Awesome video.

Thanks! These videos are super helpful and add context for first principles thought experiments. Lots of comparisons I was unaware of

Tim, great that you're making 'back to the basics' content that got me hooked in the first place!