Boeing-Sikorsky SB>1 Defiant (Model S-100)

sferrin

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The Verticalmag article states the the SB-1 hit 205 knots after 18 flight hours in 15 months from first flight.

The only points of comparison I have is Eurocopter’s X3, which hit 232 knots after ~15 fight hours in 9 months, and Sikorsky’s own X2, which hit 235 knots after 14 flight hours in 24 months. So the SB-1 progress is still fairly slow.
Interesting analysis, thank you. I have to wonder though how much the change of corporate headquarters has had to do with the lethargic progress. Very soon after Lockheed Martin (with no recent rotorcraft experience) took ownership of Sikorsky, the S-97 Raider hard landing occurred. With F-35 front and center, I doubt the rotorcraft programs are getting anywhere near equal time.

At least from my tiny corner of the big picture LM has been hands off, at least as far as CH-53K goes.
 

yasotay

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I think the hands off approach has been okay for CH53K. It is a more mature program with a relatively low threat technology ( compared to S-97 and SB>1.) Also LMCO has had a working relationship with the USMC. I imagine between nervous investors and a notoriously bad business partner in the US Army they might be reluctant to jump into the briar patch.
 

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The Defiant team has unveiled their official pitch for FLRAA: Defiant-X.

The changes from the SB>1 include an exhaust system configured to reduce the aircraft's IR signature and, perhaps surprisingly, a return to the tricycle landing gear seen in the original X-2 concepts from Sikorsky.
 

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Two points:
- Landing gear: the CG has probably migrated forward
- exhaust: see point above and IMOHO exploiting the mixing flows effect of the propeller (aggravated by the tail LERX).
 

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yasotay

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TomcatViP

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T-901 is a 3000shp class range engine planned for installation in Apache and Blackhawks! Not quite as much power as with a doublet of 3000kW T-55s but b/w overall mass and shp, the gap is thin.
 

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Although similar in size

The Defiant looks bigger... more AW101 sized?

According to this Sikorsky slide only 5-6 Defiants will fit in a soccer field landing area...
76385_sikorskyboeingsb1defiantspacingcsikorsky.jpeg


...vs. 8 Blackhawks/V-280 (according to Bell)
v-280-image10.jpg
 

yasotay

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The larger SWaP for either of the FVL contenders of course comes from the requirements to go further and faster, so no surprise there. While the football pitch (soccer field) measure is of note, I do not think it of much accord as it is very unlikely (not impossible) that anyone would risk that many aircraft in a confined space in the future given the availability of a plethora of weapons.
 

VTOLicious

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Although similar in size

The Defiant looks bigger... more AW101 sized?
In terms of external dimensions, I would still say Defiant is rather in the magnitude of Blackhawk than Merlin (Excluding height ;) ) Whereby MTOM definitely tends towards Merlin.

Btw, the width of Valor (with two 35ft rotors turning) is most likely equal to a CH-53K's rotor disc diameter.
 

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yasotay

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@VTOLicious - With a little humor it is often pointed out that the V-280 length is less than the rotor diameter of the H-60 and the width is overall slightly larger than the H-60 length. So the V-20 lands in a small landing zone perpendicular to the the way the H-60 lands. Your point is well taken, but as I have pointed out elsewhere it is the same argument that old H-1 pilots made about the H-60. Ultimately it comes down to does the increased range and speed of this particular aircraft outweigh the need to find small landing zones.
If one wants to argue about landing in streets, I would argue nothing bigger than the current MH-6 or some of the smaller Airbus products, Ka-226, and their Chinese analogue are viable. The range requirements of the U.S. Army and the desire to operate in "urban canyons" are mutually exclusive (currently). eVTOL may be viable in the future, but the weight of a combat capable platform will make it difficult in the immediate future I think.
 

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@VTOLicious - With a little humor it is often pointed out that the V-280 length is less than the rotor diameter of the H-60 and the width is overall slightly larger than the H-60 length. So the V-20 lands in a small landing zone perpendicular to the the way the H-60 lands. Your point is well taken, but as I have pointed out elsewhere it is the same argument that old H-1 pilots made about the H-60. Ultimately it comes down to does the increased range and speed of this particular aircraft outweigh the need to find small landing zones.
If one wants to argue about landing in streets, I would argue nothing bigger than the current MH-6 or some of the smaller Airbus products, Ka-226, and their Chinese analogue are viable. The range requirements of the U.S. Army and the desire to operate in "urban canyons" are mutually exclusive (currently). eVTOL may be viable in the future, but the weight of a combat capable platform will make it difficult in the immediate future I think.

The "urban fight" scenario is the driver behind the FARA requirement that limits the diameter to 40'. The range and speed requirements are lower for FARA than for FLRAA.
 
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F-14D

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As discussed elsewhere on another topic, there's a statement in the video ( :011) : "We showed that 230 knots that's what the Army asked for...". Will they be able to do the 250 knots that was at least initially what Army required and which they promised they'd easily be able to do?
 

yasotay

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I think they will be able to get to 250. I am not so sure about crusing at 250, which is/was the requirement. Have to see what the requirement is when it comes out, but it sounds like they know it was dropped to 230.
 

sferrin

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I wonder what the ride is like at 247 knots in the Defiant vs 300 knots in the V-280.
 

VTOLicious

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Btw, they have attached some kind of strake to the nose section.
 

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H_K

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Key sentence:

Has flown to a speed of 247 kt., with the engine showing some limited power left to go faster. The companies have said they hope to exceed 250 kt
 

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Just to remind anyone, 250kt is equal to 450kph, an impressive speed for a rotary wings, equal to to what early WWII fighters where capable at their best.
The 56kt transversal speed is also quite spectacular.
 

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@TomcatViP And just like those early WWII fighters the actual operational types will probably never fly as fast as the prototypes, with all the extra drag of operational kit added, high temperatures etc. So what will be a realistic “real” speed? 230kts?
 

sferrin

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@TomcatViP And just like those early WWII fighters the actual operational types will probably never fly as fast as the prototypes, with all the extra drag of operational kit added, high temperatures etc. So what will be a realistic “real” speed? 230kts?
Now compare that to the V-280.
 

bring_it_on

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@TomcatViP And just like those early WWII fighters the actual operational types will probably never fly as fast as the prototypes, with all the extra drag of operational kit added, high temperatures etc. So what will be a realistic “real” speed? 230kts?

Whatever the ultimate cruise speed requirements turn out to be (it really depends on what the Army thinks it can afford and not just "more is better") it will involve a real world number in terms of cruising during an operationally relevant scenario with a relevant payload. As they transition from demonstrators to more mature prototypes and eventually to EMD aircraft they are likely to be able to get increased performance and be better at meeting or exceeding Army requirements. Ultimately, this will come down to how much performance the Army can afford given that they'll need a lot of these.
 

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@TomcatViP And just like those early WWII fighters the actual operational types will probably never fly as fast as the prototypes, with all the extra drag of operational kit added, high temperatures etc. So what will be a realistic “real” speed? 230kts?
@bring_it_on beat me on it but the good side of having an early flight domain limited by aerodynamic side effects like flutters, is that your ability to reach that speed is unimpaired, or at least, not related to the power available (two 6000shp T-55 at maximum theoretically!). Many Airbus airliners can't go for example a notch farther than their open flight domain but they do fly daily at the edge of it (if we consider that a .05 mach something is nothing to brag about).

I would not believe that the US Army has no such priority as reliable performances and mission reach.
 
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yasotay

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At the end of the day, reliability and sustainability will be critical considerations. Logistics requirements and maintainability in austere locations will be key elements. Of note at the ongoing AUSA effort Bell has been showing their use of standard Army aviation maintenance equipment when conducting the tear down inspection of their demonstrator. They also point out that the prop-rotor is a two man carry. Savvy stuff since the senior types at that show worry about logistics, not doing "whipperdills" at the X.
 
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