Re:Australia Joins the Race for Supersonic Flight
by opwieurposiu on Wednesday May 12, 2021 @03:12PM
(#27134027)
Modern non-military jet engines are designed with high pressure ratios around 50-60 to get good subsonic cruise efficiency.
For a supersonic jet, a lot of the compression is done by the intake, so the compression in the engine must be much lower, around 10-20. This is why off the shelf engines don't work very well for supersonic.
The concorde used a pressure ratio 11.3 from the engine, but combined with the intake it was 82 when at cruise. This actually made it very efficient at 43%. During taxi and climb-out however, the low pressure ratio made it a real gas guzzler.
https://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593
Re:Australia Joins the Race for Supersonic Flight
by trhway on Wednesday May 12, 2021 @03:45PM
(#27134351)
To get to the efficient supersonic mode asap they even used afterburner. Military engines are 20-30 so they would be most suitable COTS.
Re:Australia Joins the Race for Supersonic Flight
by mshook on Wednesday May 12, 2021 @04:13PM
(#27134590)
There was a B version on the drawing board which would have dropped the afterburner...
https://en.wikipedia.org/wiki/Concorde#Range
And you're right, the ballpark fuel consumption for Concorde says your hourly rate is not that dissimilar in subsonic than in supersonic so you better fly fast quick...
Uncounted supersonic aircraft startups went bust trying to make own engines (and that with making turbojets actually being easier than modern turbofans)
For everything else, it's sixties-seventies materials, and technology.
In fact, it's much easier for example to get steel, and aluminium alloys withstanding 200C°-300C° than in sixties.
Strong actuators for control surfaces are both better, and easier to make now because of aircraft electrification.
Internal structure can be made easier with composites today than with complex forged parts 60 years ago.
And of course, supersonic aerodynamics is now much easier with computers.