Boom Technology Overture M2.2 SST

[fredymac]

Seems Japan Air Lines may be a customer if the program works out.

 

[ferpe]

https://paxex.aero/2020/07/boom-supersonic-rolls-royce-engine-partnership/

It is not a new technology engine, it is a new design engine. You’ve got knobs on an engine like bypass ratio and pressure ratio and they’re set in certain places for the 787 and you want to set them in different places for this airplane. It is moving the knobs, it is not let’s invent variable cycle or something that’s never been certified before.

Now, it's possible as the article says, that this will turn out to be impossible. But for right now, Boom definitely seems the possibility of something a lot less demanding that a new core and a variable cycle engine. A lot can be done with inlet and nacelle design, especially since they are really only trying to optimize for a single point performance, unlike the multiple points where military engines are trying to work. Having lots of excess thrust so they can take off at partial power seems like a simpler, if less efficient, solution.

The engine that does this (except using a fixed inlet instead of a multi-chock inlet) is the GE Affinity. It flies between M0 and 1.4. The problem for the Boom project is its leaders who didn't know better put the bar at 10% faster than the Concorde, that had the luxury of a straight jet (and the consequential take-off noise). You can't handle the Ram drag at M2 unless you can limit the amount of air mass that enters the engine. It's physics, every engine designer knows about it. This is why the Tu-144 changed from a bypass engine to a straight jet during its development.

The engine is the key problem for an SST, especially if you want to go above M1.6. This is where fixed inlets don't work anymore and you have a real problem with normal cores, let alone a non-military low-pressure system. Boom has been at it for four years now and has made progress on every other account. On the engine side, they are still "studying possible solutions, and if an existing core can be used". The reason is what every serious engine designer knows, you can't solve it with a fixed design. Not today with the noise standard we have.

 

[riggerrob]

If Boom Technologies are smart, they are developing bleed air systems to divert ram air away from the compressor face.
Perhaps Boom had internal doors that they are afraid to reveal to competitors.
The second generation of Boom will probably have electro-magnetic, plasma systems to steer air away from the compressor face.

 

[TomcatViP]

3D printed parts

 

[riggerrob]

We wonder whether they are using 3D Printing because of cost of materials (titanium) or whether they want to build components that are impossible (e.g. hollow) with conventional tooling.

 

[TomcatViP]

@riggerrob : Each assembly asks for components design, manufacturing drawings, detailled instructions and quality control.
3D printing helps to drive down cost canceling small elementary parts costs that otherwise would still need to be fully processed.
That also reduces iterating cost b/w R&D and production. For example when the CFD team makes a slight modification, the only thing that has to be incremented is the assembly itself. Not all the subcomponents.

In the past, machining was extensively used during prototyping to cut part nbr the same way.

It's still possible that during production they search for an alternative, looking for subcontractors that will produce the parts at a lower cost or better quality.