Boeing Vertol BV-235 (AAH contender)

[overscan (PaulMM)]

I take your point, but the drawings seem to indicate a deeper commonality than just rotor/engines/transmission. Equally, Boeing hadn't lost UTTAS when they were designing the BV.235 AAH, the programs were only about a year apart and Boeing had won a prototype contract for UTTAS when finalising their AAH- lower cost from commonality with the UTTAS might have been a plus point.

 

[iverson]

It was a way of making side-by-side seating work better for pilot visibility, but as iverson suggests, this was most likely because they wanted to reuse YUH-61 elements rather than because it was the best solution.

I doubt that commonality with the YUH-61 was a major driver of the side-by-side layout:
- the expensive part of a helicopter that is carried over between designs is the rotor/engine/transmission system. The fuselage configuration is a lesser part of the cost and engineering effort.
- the differing demands of an attack helicopter with a large gun and sensor package mounted on the nose vs a utility transport with a substantial cabin would, I think, severely limit fuselage commonality forward of the tail boom.
- without knowing the details of the competition, contractors that are downselected to the prototype stage are usually generously rewarded if they lose the competition, otherwise it would be a fool's game. Often their participation in prototyping is more profitable than that of the winning competitor, who gets the bigger but longer-term prize of a production contract. So Boeing's investment in the YUH-61 had probably already paid off so that there was nothing to recoup.
- AAH was a major weapon system program with a long time horizon, without the severe time or cost pressures that force designers to adopt hardware from existing designs. Boeing would have been very foolish to compromise their entry with features that were anything but what they perceived to be "the best solution".

My information is only as good as my memories of reading contemporary Aviation Week articles at the public library. That said, Boeing was a one of the favored contenders for what became the UH-60 program, but I don't recall it being favored for what became the AH-64 (those were the Bell and Hughes entries). After the AH-56 debacle, the program was highly politicized and the Army was anxious to avoid any appearance of risk or any controversy that would interfere with its choice of favored suppliers. To have a chance, Boeing had to depend more on its clout in Congress than it did on Army support.

While I freely admit that I don't know the contract details, my impression was that Boeing Vertol spent a lot on the unfamiliar, single-rotor configuration of its UTTAS design in the hope that this would broaden its appeal in the helicopter market beyond tandem-rotor cargo types. It needed a production contract to cover its sunken costs, not just a development contract. Having bet the business on a win, Boeing thus had to scramble for any work work it could get. In Philadelphia, where I lived, there were perennial rumors of imminent, large layoffs at Vertol. So I suspect that Boeing put together a quick, minimal effort proposal for the only other current helicopter program on offer. If they got the contract through political pull, on the basis of alleged cost saving, or in some other way, they could re-engineer the design after the fact. This wasn't all that unreasonable an approach, either. Hughes did essentially the same thing with its much better thought-through winning entry, which, in mockup, bore little resemblance to the AH-64 that emerged later.

The Army indeed raised objections regarding the practicality of the Boeing--quite possibly those you mention. But, again, based on memory alone, I don't think practical objections had much to do with Boeing's design choices at the time.

 

[taildragger]

I take your point, but the drawings seem to indicate a deeper commonality than just rotor/engines/transmission. Equally, Boeing hadn't lost UTTAS when they were designing the BV.235 AAH, the programs were only about a year apart and Boeing had won a prototype contract for UTTAS when finalising their AAH- lower cost from commonality with the UTTAS might have been a plus point.

I don't see evidence of commonality beyond the dynamic components.
- If you overlaid drawings of any 2 single rotor helicopters with similar rotor diameters and blade count, isn't there a pretty good chance that they'll show similar fore/aft proportions? Granted the tail booms show a similar shape, but that wouldn't drive the cockpit layout.
- the forward fuselage of the BV.235, where you'd expect to see the commonality if it drove the side-by-side layout, is about 30% narrower than that of the YUH-61 (assuming that the scale is constant). Once you've narrowed the structure by a third, added mounts for a sensor package and large cannon, armored it and staggered the crew stations, how much commonality could there be?
My suspicion is that someone came up with a model quantifying all-round crew visibility that prioritized the forward view and sold this layout as the ideal compromise. He was obviously able to overcome internal critiques like "Yeah, but it really looks stupid". He may have been related to the guy who sold Blohm und Voss on asymmetry (shouting down jeers of "Ja, aber es sieht dumm aus") and Douglas on bug-eye canopies (overcomming comments like "Ew, gag me").

 

[hesham]

From Aviation magazine 1973.

 

[MrWidgeon]

Late to this one, but I think the driving point of the cockpit design was overall height. This is a very flat helicopter all in all, if you collapse the main/tail gear struts & remove the gun turret it gets very flat making it possible to fit them in the lower cargo hold of a cargo 747, or double stack them in a C-5 (with a rack of course). With a tapered rack you could have put 2 of these stacked one on another in the same space as 1 Apache, doubling your helo load.