Perhaps establishing a commitment first is the answer. This concept is part of a much bigger picture. If the final answer and question are about making money, then this sort of thing will continue.
"It's complicated" while likely not a very satisfying answer is likely the best one we'd get
My take on this is that DARPA, (as per has been happening a lot of late) was aiming for a 'quick' program leading to an operational or at least operationally available booster. Boeing was likely looking for a 'profit' and possible commercial follow ons. In the 'big picture' sense, (and at the time it was initiated at any rate) a reusable booster was a distinct possiblity and had applications both as a "light" and "quick" launch system. What seems to have been lacking was a sense of how fast the operational technology was in fact changing. (And don't get me wrong, what DARPA had in mind as rerquirements are STILL not available today and there's no one who can actually meet the requirements but that's less technology than operations and market driven)
Seriously though, what did they think they were going to learn that they didn't learn from RASCAL? (THAT would have been truly useful. The engine mods could have found use in many applications.)
Well for one thing RASCAL didn't show that you could in fact turn a very high performance RS-25 into a high-use-rate AR-22 till they went and built it
(And note I AGREE with the need to get more work on the RASCAL engine mods done, that stuff would have and would be worth its weight in gold since it has so many applications beyond 'just' space launch)
Unfortunatly I get the feeling DARPA was to focused on the engines, (even though that was actually a lagging part of the program, go figure) and getting to rapid operational, (rather than research) use that they overlooked way to many basic questions in the design. Followed up with the whole thing pretty much being a 'one-off' design and program despite the push towards an operational rather than research program and it was going to run into problems prettly quickly anyway. In this case they were again aiming more for an operational rather than research vehicle but planned to 'partner' with a bigger aerospace firm with more capability and a higher chance of being able to meet the 'needs' should they in fact get to an operational rather than research program state.
The downside of course to such a 'partnership' is that if Boeing got bored or needed to change focus then they can and will, (and did) step away which would leave the program dead in the water. On the Gripping-Hand of course going with a leaner, more 'hungry' partner such as Mastesen while less likely they'd drop out also means there's much less chance they could move from a one-off research vehicle to series production without bringing in a bigger partner eventually so why not do so from the start? It's a seductive logic really.
I thought it was because DARPA wanted a serious investment from the company because of the probable commercial opportunities.
Comparativly how much 'skin' did Boeing put into the game compared to DARPA? And DARPA by it's nature isn't likely to lead to either large scale operational or commercual oppotunities so that's up to the 'commercial' partner to both asses and work towards. Boeing (and really NG/LM) from the begining didn't seem all that interested in a commercial application and despite the stated goal of moving towards a military usable operational system the payload and other capabilities the program would have demonstrated were pretty small and the overall justification weak. But there's a truism here in that the bigger the vehicle the vastly more expensive it becomes even, or especially if it's a limited number build program. Going small is usually cheaper but then scaling it up isn't going to be 'cheap' in any sense of the word and likely Boeing could see no end product where they didn't lose money in the deal despite DARPA footing the initial bill.
I thought it was because DARPA wanted a serious investment from the company because of the probable commercial opportunities.
Indeed. Unfortunately, DARPA then went for what they thought would be the 'safe' option, Boeing. Or rather the company it used to be and what DARPA's higher ups still thought it was.
Again I have to point out that there's a consistant 'logic' behind this path if you assuem that the end product is going to be an military operational or commercial launch vehicle booster. Boeing's a logical choice in that they have the needed infrastructure and industrial base to pull that off where as the other closest competitors (NG/LM) were far less capable and Mastesen, while they could likely pull off a research vehicle were in no position to move towards an operational or sellable vehicle without partnering with one of the bigger companies. I don't think it's a CORRECT logic mind you but it would be a compelling one and in context makes sense as to 'why' Boeing was chosen, but that comes right back to the basic premise of the program and what it was (in theory) trying to prove.
Given that the one thing the program HAS accomplished, (10 runs on the AR-22 in less than 10 days with a minimum of maintenance) while rather amazing in and of itself it NOT in fact as amazing as showing you could do it with a Mach-10/suborbital airframe attached with the same ability which was in fact the whole point of the program. And that's pretty much for me where the whole 'logic' chain of going with Boeing tends to break down because that's going to cost 'someone' a pretty penny, especially when you factor in all the requirements and that in and of itself should have been obvious to Boeing from the start. Which is why I have to wonder if they were even serious from the start given how little work they seem to have actually done towards an operational vehicle, even a 'research' one.
It's not that Boeing has fundementally 'changed' its nature because that 'change' is over a decade in the past when they decided to NOT stay a standard government contractor and went back to making commercial aircraft as a main focus. The 'optics' here is that Boeing dabbled in the XS-1 program as long as they could in the realm of the 'cheaper' work, (CFD, simulations, sub-scale wind tunnel testing, etc) and kept it's Rocketdyne folks busy with the AR-22 but the moment it looked like they were going to have to start sinking 'real' money into the development program they quite instead. I'm seeing it less as Boeing not willing to 'risk' things but more they are less willing to become involved in a government program that does not hold a significant end-goal contract for them that does not take away resources and capability they can instead put towards commercial applications.
Does that make any sense?
Randy