[buildsjets]

Every major and minor engine manufacturer punted, so now they're making their own. https://boomsupersonic.com/symphony

Hired an experienced propulsion guy away from Boeing to run the show. https://boomsupersonic.com/team-members/scott-powell

They are not going to be able to do it, my opinion. There are very few people in the world who have deep experience doing 3D CFD on supersonic turbofans, I've talked to a few of them and none have been headhunted. The will need good analysis work, they are asking for a LOT out of a single stage fan. They certainly will not have the metallurgical research and manufacturing technologies of the engine manufacturers to use. But best of luck to Scott, his Porsche GT3 was getting kind of old and needs to be upgraded to the latest model.

[hef19898]

If they hired a propulsion guy from Boeing to develop a new super-sonic engine, Boom fucked up. Boeing, same for Airbus, doesn't develop or built engines, let alone super sonic ones.

But dor sure, said Boeing hire will be royaly paid for his service, good for them. And good for Boom, a prominent Boeing hire will make fundraising so much easier.

But sure, as if building a new commercial airframe manufacturer isn't hard enough, becoming a new jet engine manufacturer on top of that is a winning strategy...

[buildsjets]

In the specific case of Mr. Powell, I would agree that his skill set is primarily in the management of procuring and integrating of new engines from engine vendors into new airframes, and in the detail design of engine accessories and externals, and he is not experienced in the design of internal turbo machinery. And that's where the high risk for Boom is.

However you would be completely mistaken to think that Boeing, and Airbus, and my friends down there with Embraer, do not have people who actively pursue and develop the core technologies needed to develop, analyze, and test all types of turbine engines, even if they do not result in market products. It is a necessary tool in order to evaluate offerings from the different competitive engine vendors. And at the senior level of engineering, there is basically a revolving door between the airframe manufacturers, the engine manufacturers, and a few of the high-level engineering focused airlines. People are constantly jumping around between them, there is a lot of cross-pollination going on.

[hef19898]

Yeah, I know some of those engineering managers. They all work best in well-established, large orgs with people knowing the ins and outs of their jobs.

The last time they actually developed something is quite a while ago. And managing engine suppliers, and component suppliers only gets you so far in developing the engines yourself. And we are talking super sonics ones.

[ghaff]

Designing airframes isn't easy but aren't really novel. This is about coming up with engines that don't have noise concerns and have economics that would allow airlines to operate aircraft at prices that aren't that out of line with current ticket prices. It's not at all clear how big the market is for very premium tickets for supersonic travel is transatlantic and transpacific has a bunch of other range issues.

[hef19898]

Conventional airframes are not novel, building an aircraft is still incredibly hard so.

Civilian super sonic airframes so are novel, nobody did that since the days of the Concord and its Tupolev clone.

[consumer451]

This is a tangent, but you are well informed in the space, and I would love to read your opinion.

There is a new heli player trying to start from clean-sheet, called Hill Helicopters.[0] They are building a sleek new carbon fiber fuselage, but what I am wondering about is the fact that they are also making their own turbine engine.[1]

I have assumed that their new turbine is the hardest part of their plan, am I correct in that assumption? Is it crazy, or not crazy, that they are trying to do this themselves?

[0] https://www.hillhelicopters.com/

[1] https://www.hillhelicopters.com/gt50-engine

[buildsjets]

I would say it is not impossible for them to do it themselves if they are adequately funded, but I question the wisdom of choosing to do so rather than buying an existing certified turboshaft engine off the shelf, of which there are many in that power range. Also, that seems like an excessive amount of power for that size helicopter. A similar horsepower engine is the Pratt-Whitney PW206B, used in the Eurocopter EC135. But the EC135 is a much larger helicopter and has twice the payload capacity of this design.

The engine itself is a fairly standard centrifugal compressor design, not particularly challenging from an engineering, or material science standpoint. But with no new technology being brought to the table, there is no performance reason roll your own engine, and you are going to have to beat existing engines that have decades of refinement behind them.

I know of two other companies developing microturbines that are considerably smaller than this in an market where there is no real competition, with some cool new technologies like regenerative microtube recuperating heat exchangers. One of them is in development, one is flying their turboprop and developing their turboshaft.

https://www.turbotech-aero.com/

https://turb.aero/

There is a design/prototyping/manufacturing company called ConceptsNREC https://www.conceptsnrec.com/home that specializes in turbine engine and pump design. They do analysis work for basically every jet engine manufacturer and automotive turbocharger manufacturer, have manufacturing facilities to prototype just about every part of a jet engine, and an extensive testing facility. I would just about bet that Hill has used their services in the design and prototyping of their engine. It's a great place to work if you have a PhD in aerodynamics but want to live in rural Vermont. They also sell a CAD design and CFD analysis software package specific to turbomachinery.

If you like industrial stuff, here's a video of their prototype shop, showing some of the parts they make. My favorite is a tiny titanium impeller for a jet fuel starter system on the F-22, at 3:35. It's about the size of a quarter, and took 40 hours to machine with an 0.020" / 0.5mm diameter ball end mill. I've met both the guys in the video, they are brilliant machinists, but definitely not well polished youtube influencers, lol. https://www.youtube.com/watch?v=6v98_oxqY7E

[ghaff]

I wish them the best but, even if they can get the technology to more or less work, the economics and regulatory environment are pretty tough.

At the end of the day, it's almost certainly going to be an expensive airline ticket and even if United was (rather inexplicably) touting Boom in their advertising, I'm not sure how many customers there are to pay out-of-pocket for supersonic flights that are likely to be a premium over current top-end seating. I'd love to zip over to Europe a lot faster from the East Coast of the US. But I'm not going to pay as much to save time as I would for the rest of my trip.