Sikorsky SB > 1
 

A couple of agility data points I would be interested in hearing the results on would be hover points: 1) F/A pulse or step input and 2) Lateral pulse or step input at maximum control input rate. Both V-280 and Defiant.
Otterotor

Commando.....there is a built in fallacy to this "less is more" idea....because in reality "less is less"....you start losing aircraft by becoming predictable or for any other rreason such as putting more eggs in fewer baskets....losses can quickly be your un-doing.

Otherwise the logistics issue you describe works fine.

When is "fewer" in reality "too few"?

The reality is we're going to have less assets and resources available in the future. The threat environment is also going to be higher. Given that, the question becomes what's the best way to reasonably achieve our goal? You may indeed be able to have two UH-60s for each V-280, but that's just one component. What gets the mission done and what it costs to do so is really the question. Once in production we could probably turn out H-19s real cheap. Of course we'd have to have a lot more of them, the maintenance would be horrendous and we'd have to have lots more places for them to operate form. Similarly, We could buy a slug of P-51s or F-86s for the price of an F-15, but would that be a smart move?


Given today's threat and fiscal environment (we're going to have fewer aircraft and bases even if we built H-60s forever), the cruise and range desires for FLRAA make sense to me.

We've been discussing rotor diameter of SB>! and how many will fit in an LZ. Came across this picture of it in a hangar at some kind of recent presentation. Look at the height! How will we operate and maintain this in a forward area?
https://cimg7.ibsrv.net/gimg/pprune....001410e800.jpg

Looks to be (just from eyeball) about the same height as the aft rotor on a Chinook, which seems to manage just fine, albeit with a larger logistical footprint than a typical small rotorcraft.

Except that rotor height on a medium lift asset that does not have the range to self-deploy makes it a non starter to fit into any airlift platform, much less a deck elevator and into a ship hanger.

A picture is worth a thousand words. This is one tall MutherFr. Sikorsky- Boeing always talk about rotor diameter and overall length, but never height. Chinook is 18.3 feet maximum height. My eyeball says Defiant could be taller to top of the hub. Now lets talk about rotor hub drag.

I definitely agree on the maintenance aspect. Think of the crane that is necessary not only to remove the rotor but to lift the gearbox! Based on aircraft proportions, that coaxial gearbox probably weighs more than a CH 47 gearbox also.

The thing is, this aircraft is to be a Black Hawk, not Chinook replacement. It would have the penalties of the CH-47's height but not the lifit and volume benefits. Also, the Chinook has maintenance platforms built into the housing of its aft rotor. How do people get to that upper rotor/hub without some pretty tall scaffolding?

Whenever Sikorsky depicts a maritime SB>1, it's always shown based on an LHA/D or larger ship. DDGs and the like appear to be non-starters.

Some wag elsewhere (not me) said that in this case you remove the fuselage from the transmission.

Just Dropped
 

It's good to see they've got another flight under their belt. Note the operative words in the video about demonstrations are "going to" instead of "have".

Another statement concerns me, "We showed that 230 knots that's what the Army asked for..." . Last I heard, what the Army asked for was 250 knots as the threshold, which the SB>1 team originally claimed they'd be able to achieve. Hopefully the Army hasn't lowered the requirements to accommodate one of the contractors.

Also notice they never mention range. LR in FLRAA is for long range. Remember when the Sikorsky program manager said they were proposing both a high speed config or a "long range" config and pressing the Army to select which is more important. So it is clear they will not meet any of the original program goals while their competitor has.

The FLRAA program speed requirements have indeed been lowered in addition to lots of other requirements changes over the last year... this doesn't change the fact that SB>1 had a design Vh much higher than 230 knots and it's taken a long time to get to this reduced goal.

As of Dec. 2019 I believe they were still @ 250 knots and in their Dec. 2020. announcement I believe the Army said the reason they were limiting further competition to just Valor and Defiant was because they said they were the only two competitors they were confident could meet the requirement. You are correct in stating, though, that even if the requirement was lowered, Sikorsky Boeing said they could do 250.

The parallel Marine Corp effort for a new medium lift which is paralleling the FLRAA has the speed requirement broken down into a required cruise speed of 280kts and a desired of 320kts, both of which are well within reach of existing V-280 technology. Does the dumbed down FLRAA requirements have similar required/desired metrics? if so, can anyone share the wording. Can't see the Army wanting to, once again, take an aircraft inferior to the Marines (e.g. V-22, CH-53K....).

This is quoted from a Breaking Defense article published April 05, 2019

Speed: The Army’s minimum acceptable cruise speed, the threshold requirement, is 250 knots (288 mph); its preference, the objective requirement, is 280 (322 mph, incidentally the intended cruise speed of Bell’s V-280). The Marines’ threshold is 275 knots (316 mph), almost as high as the Army’s objective; their objective is 295 (339). And that actually understates the difference, because the Army only asks for this performance at maximum continuous power — the highest the engine can sustain over a long flight — while the Marines want it at 90 percent of maximum continuous power.

The Marines have even higher speed requirements for brief sprints, something the Army doesn’t address".

Fastest level flight speed so far for SB>1 is 230 knots (264.7mph); for V-280 it's 305 knots (351mph).

Bell Dismantles SB Offering
 

Bell has announced the retirement of the V-280 after it has demonstrated all original FLRAA requirements in a three year/214 flight hour campaign. During this effort the aircraft demonstrated speeds 25+ knots above Bell's goal and 55+ knots above the original FLRAA goal. This compares to the SB-1 barely reaching a speed 20 knots below the original speed goal. As to other program goals the V-280 demonstrated those in flight testing on the actual aircraft while SB continues to promise future attempts to try to achieve in flight or pushing simulations as an acceptable alternative. Bell noted this in their end of testing press release with:

This level of trolling will make it difficult for the Army to give SB any credit for not demonstrating something Bell was able to. Now that the SB-1 performance shortcomings have been bared for all to see, it time for asking why SB could not achieve the requirements even when they were given an extra 1 1/2 years to try to catch up. In this time SB was only able to accumulate around 15% of the V-280 flight time. One needs to ask: What are the concept or reliability issues with the ABC that make it unsafe to even test, let alone risk our warfighters in?

Initiating high g turns, rolls and or dives, causing failure to maintain rotor separation. Safe separation is something never demonstrated by the X2, Raider or Defiant, under conditions of a hard maneuver. These hard maneuvers should be demonstrated by a real aircraft, including when there are strong crosswinds.

The Raider that crashed is proof the rotors are too close to each other. The Raider unexpectedly rolled to one side, then as the pilot corrected the roll, the rotors hit each other. The close spacing of the rotors decreases drag substantially. I have to believe Sikorsky has already told the Army that their demonstrators can't pull high g maneuvers. But that they will increase rotor spacing for production. Which will make a slow, tall Defiant even slower and taller.