Thursday, December 27, 2018
The SB-1 Defiant breaks cover at last
The Sikorsky-Boeing SB-1 Defiant helicopter, a competitor for the US Army's Future Vertical Lift program, is getting closer to first flight next year. The joint venture has just released pictures of the first prototype on the runway in Florida. Click either image for a larger view.
It's hard to judge scale without a reference point, or accurate dimensions provided by the manufacturer, but my first reaction is that it's bigger than I thought it would be. It's supposed to be a Blackhawk-class replacement, but it's clearly taller than its predecessor, and possibly broader as well, although that may be an optical illusion caused by the wide tailplane. Of course, it's still significantly narrower than its rival in the FVL competition, Bell's V-280 Valor, which we've visited in these pages before. The Valor's wing, with rotors at its tips, is probably at least 50% wider than the Defiant's rotor configuration, and perhaps more.
I've mentioned in a previous article that I find the Valor's width excessive from a tactical perspective, no matter how effective it may be from a technological or flight perspective. I don't know whether the same applies to the SB-1's greater height. I can see it having disadvantages in flying nap-of-the-earth, as in the example I cited in the earlier article, but I'm not sure that would be as big a disadvantage as the restrictions imposed by a fixed wing. I suppose only careful testing will find an answer. However, I do find it interesting that Russia's attempt to come up with a FVL program of its own has focused on the same coaxial rotor concept used by the Defiant. It may be that's an easier technology to develop and maintain than a tilt-wing aircraft. I'd also like to see how the coaxial and wing designs compare on the deck of an amphibious landing vessel. I suspect one might be able to fit more of the former onto the deck than the latter.
It's also interesting to note the joint proposal from AVX Aircraft Company and L3 (shown below) for the US Army's Future Attack Reconnaissance Aircraft (FARA) program, announced earlier this year.
It also uses coaxial rotor technology, like the Defiant or its smaller sibling, the S-97 Raider (shown below), which will be Sikorsky's submission for the FARA competition.
So far, more manufacturers (in multiple countries) appear to be focusing on coaxial rotor technology than on tilt-wing. I think the cost, complexity and sheer size of tilt-wing tactical helicopters are going to make that design more vulnerable, from both tactical and budgetary perspectives . . . but that's just me, basing my views on what may be an outdated and/or technologically backward point of view. (For an interesting comparison of the two approaches, including technological and tactical considerations, see here.)
As before, let's hear from readers who have up-close-and-personal experience with tactical helicopter operations. What do you think?