Boom

I swear boom spends more on puff pieces than any other aerospace company. They continuously make claims they will do things by certain dates that are unrealistic.

They claim they will be delivering airplanes to United that would be in service in 2029:

https://boomsupersonic.com/united https://www.cnbc.com/2021/06/03/united-will-buy-15-ultrafast...

However new aircraft take 5-9 years to certify and they have not yet even built one! Not to mention new engines take a similar amount of time and they are supposedly building their own brand new engine, which is a substantially harder task.

Now they are claiming the first "test" flight will be in 3 years despite the fact that they still don't have a plane or an engine built. I hope someone over their let United know they are going to be a little late. Their website hasn't amended to article to say they were wrong.

I wonder if we can look to history to see how long it takes between when they say they will fly something and when it actually flies? Oh right, we can!

https://en.wikipedia.org/wiki/Boom_XB-1

"The original design was unveiled at Centennial Airport in Dove Valley, near Denver, Colorado, on November 15, 2016,[6] and it was initially intended to make its first subsonic flight in late 2017"

"The XB-1 performed its first flight test on March 22, 2024, flown by test pilot Bill Shoemaker from Mojave Air and Space Port.[1]"

They were only 7 years off but we all make mistakes.

Astro Mechanica

- LNG isn't used because weight needed for fuel tanks that will keep it cold enough to stay liquid cancels out any benefits. For anyone interested in a famous failure of a similar idea: https://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan - I don't know what analysis they are doing that makes them think reducing the number of passengers and going to supersonic is possible while maintaining current ticket prices... but it's not. - Engine and plane makers are not allowed to run airlines. Anyone unfamiliar with the field can look up United Aircraft. - Their engine does sound like it's trying to do some cool things. I kinda suspect it's just a fun way to pass the time on the governments dime given all the other unrealistic stuff they are talking about though.

Hermeus

These folks are legit. Don't know if they will be successful but outsourcing the jet engine and focusing their work on the ramjet and the integration of the two makes alot of sense.