Sikorsky-Boeing SB-1 Defiant

Helicopters and tilt-rotor aircraft
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boilermaker

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Unread post12 Nov 2020, 05:44

Looks like we are at BERP IV iteration. I had no idea about this development. I wonder what kind of tip they use for these new compounds. The blackhawk has the simple swept tip.

https://www.flightglobal.com/berp-iv-gi ... 52.article

https://dspace-erf.nlr.nl/xmlui/bitstre ... sequence=1

https://www.semanticscholar.org/paper/B ... c9adc?p2df
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AHS2009_BERPIV_Dynamics_Moffatt.pdf
Aerolasticity of BERP IV
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marauder2048

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Unread post13 Nov 2020, 00:42

boilermaker wrote:Looks like we are at BERP IV iteration. I had no idea about this development. I wonder what kind of tip they use for these new compounds. The blackhawk has the simple swept tip.


HH-60W has the same growth rotor blades found on the S-92. Same anhedral.
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zerion

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Unread post25 Jan 2021, 19:51

Defiant-X: Sikorsky, Boeing Unveil FLRAA Design

The companies’ proposed Future Long-Range Assault Aircraft (FLRAA) to replace the UH-60 is a sleeker, stealthier version of the prototype SB>1 Defiant now in flight tests. Can it beat Bell’s tiltrotor?

WASHINGTON: Sikorsky and Boeing did “hundreds of trade studies” and consulted extensively with the Army to refine their SB>1 Defiant compound helicopter into the new Defiant-X, officially unveiled today.

Image

What’s the difference? The companies were cagey about details, and they said they may make further tweaks. But between their guarded statements and the keen eyes of fellow reporters on the conference call, we can highlight a few visible changes in the images released today:

Defiant-X has beefed up landing gear, having gained a nose wheel that the SB>1 Defiant lacked. (SB>1 had two large wheels forward and a small wheel on the tail – check out these close-ups). This almost certainly adds weight, but, the companies said, it will improve stability on rugged frontline landing zones.

Defiant-X gets rid of the prominent exhaust outlet that SB>1 had below its engine. That helps “reduce thermal signature,” the companies said in a statement. In other words, the new design sheds its engine heat in a different and less detectable way, making it stealthier against enemy infrared sensors and harder to target. The companies said they’re still deciding which specific engine to install. They’ll have to find the best balance of raw power, ease of maintenance, and heat.

Finally, Defiant-X has a more sharply angled nosecone and a pronounced ridge on the back half of the fuselage. Such “mold line” changes improve the aircraft’s “aerodynamic handling,” the companies said. There’s no word on whether they also improve its speed, a high priority for the Army – and an area where the SB>1 has lagged its rival, the Bell V-280 Valor...

https://breakingdefense.com/2021/01/def ... aa-design/
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usafr

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Unread post26 Jan 2021, 02:03

A strong side wind is going to blow that sucker over on its side. Remember, you heard it here first.
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madrat

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Unread post26 Jan 2021, 13:55

Tail strikes will never be a problem, I'm sure.
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aaam

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Unread post03 Feb 2021, 08:37

FWIW,

Interesting datum to consider when analyzing their claims: According to Flight Global, since its delayed first flight in March of 2019, they've only flown the SB>1 31 times with a total flight time of 26 hours.
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madrat

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Unread post03 Feb 2021, 14:16

Seems like tall helicopters will be a real bitch to maintain in the field. Neither Defiant nor V-280 impress me as sustainable.
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strykerxo

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Unread post03 Feb 2021, 17:34

usafr wrote:A strong side wind is going to blow that sucker over on its side. Remember, you heard it here first.


Yep, I read about Chinock's being blown over all the time...
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usafr

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Unread post04 Feb 2021, 01:13

Ever heard of the aerodynamic design philosophy " if it looks right it usually is right?"

That thing does not look right. It looks too tall for its landing gear width.

If you are more comfortable with technical terms, it looks "tipsy."

Chinook's are wide and squat by comparison, with a wheel on each corner like a go cart.

I do not believe you when you say you hear of Chinooks blowing over all the time.

That is just "fake news."

Do not believe it.
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charlielima223

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Unread post20 Oct 2021, 08:53

Earlier this month the Sikorsky went a little bit faster than previously tested. While still behind what Bell's tilt rotor design has demonstrated the Sikorsky design seems to be gradually hitting its stride...

https://www.flightglobal.com/helicopter ... 95.article

The Sikorsky-Boeing joint team behind the SB-1 Defiant, a co-axial helicopter with a pusher propeller, believes the rotorcraft demonstrator can go slightly faster.
***
The SB-1 Defiant has hit a top speed of 247kt (457km/h) while flying level in a test, but Bill Fell, FLRAA principal test pilot, says he believes the aircraft can go even faster.

“Even when we went 247kt, we had engine power available,” he says.

Fell declines to say specifically how much faster he thinks the SB-1 can fly. “I think anything above 250[kt] is going to put a smile on my face when I get home,” he says.

The proposed Defiant X is designed to be able to fly at 230kt in cruise, which is the US Army’s requirement for FLRAA. Speeds near or above 250kt would be considered a dash speed.

Bell’s V-280 demonstrator has reached 300kt in flight testing. Because the tiltrotor can fly horizontal on its wing it is more efficient and fast in cruise mode.

Against that speed, the Sikorsky-Boeing team has argued that the Defiant X would more manoeuvrable during its final approach to the landing zone. For example, the helicopter can reverse its propeller and go from 200kt to a hover in about 800m (2,640ft), says Fell.

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element1loop

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Unread post20 Oct 2021, 09:13

SB-1 is such an impressive aircraft but when it comes to dealing with China nothing is going to do it better than V-280. Range, payload and speed will be incredibly good, it'll tip the scales towards survival and operation success much more often, IMO. I hope Pentagon and Congress get both, but a lot more V-280 is the game-changer if there can only be one.
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aaam

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Unread post23 Oct 2021, 07:37

element1loop wrote:SB-1 is such an impressive aircraft but when it comes to dealing with China nothing is going to do it better than V-280. Range, payload and speed will be incredibly good, it'll tip the scales towards survival and operation success much more often, IMO. I hope Pentagon and Congress get both, but a lot more V-280 is the game-changer if there can only be one.


Assuming both meet their promises and the Army requirements (and if one doesn't than the decision is made right there). Buying both would mean procuring two different aircraft when one will do. You'd have separate procurement actions, two EMDs, two different logistics pipelines, two separate training pathways, etc. Army doesn't want to spend that kind of money even if they had it, which they don't, which would mean something else they need couldn't be funded.That'd be like USAF buying both the F-22 and F-23 or both the F-16 and the F-17.
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