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-   -   Sikorsky SB-1 flies for first time (https://www.pprune.org/rotorheads/619699-sikorsky-sb-1-flies-first-time.html)

SplineDrive 22nd Sep 2019 15:48


Originally Posted by riff_raff (Post 10575778)
Haven't seen the actual RFI document yet. Responses to some sections are due Nov. 22 and responses to other sections are due Jan. 1. Be interesting to see if they get any proposals for innovative propulsion/aero concepts that meet their objectives and truly merit funding. Giving serious funding to small companies to rapidly develop innovative concepts applicable to AURA objectives is also a good way to keep the existing JMR/FVL teams on their toes.

The requirements, of course, are key. If the Marines want something too different than either FARA or FLRAA, the industry is looking at yet another rapid development program of an advanced VTOL craft... which is exciting, but I think the industry is getting a little tired. One of these programs needs to become a fully funded program of record and not a one-off cost share project.

After being in this business for a couple of decades, I can tell you that if the 295+ knot speed is firm, it won't be an edgewise flow rotor. It's possible to hit those speeds, but not efficient enough to have good range and be a balanced platform. The shipboard compatibility requirements and exactly which hangers it needs to fit in will also heavily drive the design for AURA.

CTR 22nd Sep 2019 23:10


Originally Posted by SplineDrive (Post 10576230)
I think the industry is getting a little tired. One of these programs needs to become a fully funded program of record and not a one-off cost share project. .

Not just the primes, component suppliers are also about to call it quits on investing on new DOD programs with high risk of no future contracts.

SansAnhedral 23rd Sep 2019 20:27


Upon successful PSTB endurance envelop expansion, we expect to be positioned to quickly expand the aircraft flight envelope later this summer
Today is the first day of fall. And yet again, Sikorsky misses another milestone with this program. Literally every single date, whether it was contractually driven or self-imposed, has been missed or slipped by both the Defiant and Raider teams. It's simply mind boggling.

I have been following these programs for going on 10 years now, and have been suspicious of most of the claims from a technical standpoint nearly the entire time (hell just look at my post history). I cannot fathom how there has been almost zero pressing done by the aerospace and defense community and media journalists regarding the repeated failures, complete opacity, and outright lying that has come from Sikorsky throughout.

Nearly weekly there are news stories regarding FVL with headlining pictures displaying Defiant and breathless commentary about how its a leading contender for FLRAA. Does anyone else feel like they are taking crazy pills reading these pieces year in and year out? Will Defiant even fly again by year end now? Even the laughable historical lifetime combined flight rate for all ABC aircraft of 1 hour / month far exceeds what Defiant has achieved thus far.

etudiant 23rd Sep 2019 23:10


Originally Posted by SansAnhedral (Post 10577628)
Today is the first day of fall. And yet again, Sikorsky misses another milestone with this program. Literally every single date, whether it was contractually driven or self-imposed, has been missed or slipped by both the Defiant and Raider teams. It's simply mind boggling.

I have been following these programs for going on 10 years now, and have been suspicious of most of the claims from a technical standpoint nearly the entire time (hell just look at my post history). I cannot fathom how there has been almost zero pressing done by the aerospace and defense community and media journalists regarding the repeated failures, complete opacity, and outright lying that has come from Sikorsky throughout.

Nearly weekly there are news stories regarding FVL with headlining pictures displaying Defiant and breathless commentary about how its a leading contender for FLRAA. Does anyone else feel like they are taking crazy pills reading these pieces year in and year out? Will Defiant even fly again by year end now? Even the laughable historical lifetime combined flight rate for all ABC aircraft of 1 hour / month far exceeds what Defiant has achieved thus far.

There are so few remaining suppliers in the sector that a publication would be courting suicide to alienate any of them.
Hence all news reports are slightly massaged press releases, rather than independent opinions.
Bad for the industry and bad for the tax payer, but short term profitable.
Imho, the relevant precedent is the pre WW2 French defense industry, it produced some truly superb gear such as the Char 2bis, was hugely profitable and an abject failure from a national perspective.

The Sultan 24th Sep 2019 00:30

Sept 2019 was suppose to be the conclusion of the FVL assault tech demo phase. It looks like the Marines are sticking to that with their AURA schedule of having RFI response in by Jan 2020. Defiant will obviously have no positive influence on whatever Boeing submits.

Meanwhile the V-280 is racking up flights doing demo’s or training with a lot of low altitude fully converted high speed passes and helicopter mode agility maneuvers. Quite impressive relative to speed, low acoustic signature, and looks.

SansAnhedral 10th Oct 2019 15:38

Interesting article regarding recent SB1 model wind tunnel testing

NFAC tests next-generation military helicopter | Aerotech News & Review


From the NFAC perspective, the wind tunnel test was successful,” Wang said.
One wonders if a seemingly unnecessary qualifying statement like that has some implications.

The Sultan 10th Oct 2019 20:18

2019 is a little late to do wind tunnel testing on a design done in 2015. It would appear these tests were trying to determine how to fix the problems uncovered on the S-97 and carried over to the Defiant which has limited it to basically 200 kts (60 kts short of the X-2). We should know at AUSA in four days if they are making design mods to the Defiant to get closer to the 280 kt cruise required or scrapping the program outright.

etudiant 11th Oct 2019 00:39


Originally Posted by SansAnhedral (Post 10591226)
Interesting article regarding recent SB1 model wind tunnel testing

NFAC tests next-generation military helicopter | Aerotech News & Review



One wonders if a seemingly unnecessary qualifying statement like that has some implications.

The phrasing certainly leaves open the possibility that although the tests were successfully completed, the results were disappointing.
Stuff like that happens in the VTOL business.
I remember the Rockwell XV-12, a design based on the concept that a jet flux could entrain considerable ambient air, enough to add about 20% to the lift produced.
It worked fine in scale models, but not when scaled up to full size. Perhaps something similar is happening here.

The Sultan 16th Oct 2019 11:56

Progress?
 
From the second day AUSA press release:


The SB>1 Defiant is back in the air, reaching speeds of 20 knots on its fourth test flight. It should reach the Army-mandated minimum speed of 230 knots by the end of March, “if we have no other significant things we learn along the way,” Boeing program manager Ken Eland said here this morning.
I guess this might be considered progress. A good PR headline would have been “SB-1 Doubles Flight Envelope in One Leap.” So six months to get to 20 knots and another 4 to 6 weeks before they will attempt a fifth flight. They also state they will reach 230 kts plus by March, but hedge by not saying what year.



SplineDrive 16th Oct 2019 12:23


Originally Posted by The Sultan (Post 10595641)
From the second day AUSA press release:

I guess this might be considered progress. A good PR headline would have been “SB-1 Doubles Flight Envelope in One Leap.” So six months to get to 20 knots and another 4 to 6 weeks before they will attempt a fifth flight. They also state they will reach 230 kts plus by March, but hedge by saying what year.


And no commitment to reach the SB>1 design speed at all.

SansAnhedral 16th Oct 2019 14:56


Originally Posted by The Sultan (Post 10595641)
From the second day AUSA press release:



I guess this might be considered progress. A good PR headline would have been “SB-1 Doubles Flight Envelope in One Leap.” So six months to get to 20 knots and another 4 to 6 weeks before they will attempt a fifth flight. They also state they will reach 230 kts plus by March, but hedge by not saying what year.



20 kts!!!

https://cimg7.ibsrv.net/gimg/pprune....aa81d63247.gif


The Sultan 17th Oct 2019 04:00

Who Writes This Stuff?
 
Just think someone at Sikorsky/Boeing is congratulating themselves with getting this info in the press:

https://breakingdefense.com/2019/10/...-inches-ahead/

They seem to think their continued “development” of the Defiant until the end of 2020 will be beneficial to the programs it was applicable to. Problem is the Marines want responses on their program no later than January and the Army in the first quarter of 2020 while they will still be struggling to get above 120 knots.

Got to wonder if the Marines/Army will say enough and save a billion dollars or so by selecting the V-280 derived offering from Bell and fast track development and fielding.

SansAnhedral 17th Oct 2019 13:58


https://cimg2.ibsrv.net/gimg/pprune....76eb5eed9c.png

CTR 15th Nov 2019 10:54

Any New Flight Test Status Updates?
 
Any new Sikorsky Defiant flight test status news? It has been a month with no press releases or leaked intel.

Just curious, not trolling or looking to rehash history.

SplineDrive 15th Nov 2019 14:58


Originally Posted by CTR (Post 10619111)
Any new Sikorsky Defiant flight test status news? It has been a month with no press releases or leaked intel.

Just curious, not trolling or looking to rehash history.

There was another video posted a few days ago on YouTube showing Defiant doing low speed flights with some truly "beast mode" rotor head fairings installed. No word on if this was a check flight for the fairings or the 40 knot expansion mentioned in the media around AUSA.


The Sultan 15th Nov 2019 17:58

Fairings look more like they will add drag.

IFMU 16th Nov 2019 12:40


Originally Posted by The Sultan (Post 10619382)
Fairings look more like they will add drag.

That's why they don't make decisions based on looks! This cracks me up.

The Sultan 16th Nov 2019 14:43

IFMU

Did the fairings on the S-97 work out as expected? The 97 is 50+ knots short of design speed not due to its horrendous vibration, but because of drag. As referenced elsewhere Sikorsky was back in the wind tunnel this year trying to come up with a solution. As the SB-1 fairings look even worse than the 97 it appears that testing was a bust. Will be surprised if they make it much past 200 knots, which is now 80 knots short of the new minimum cruise for the FLRAA.

CTR 16th Nov 2019 15:47

Thanks for the Update
 
Splinedrive,

Thanks for the link to the video. It didn’t come up on my usual searches.

Sultan, I believe the 280 KT requirement is a USMC AURA spec, not currently a US Army spec.

It would be a shame however if the Army for a second time opted out of a Tiltrotor aircraft.

SplineDrive 16th Nov 2019 17:07

Fairings can be pretty large and bluff body looking and still reduce drag, so I’m confident that SB>1’s rotor fairings will be an improvement over the comparatively inelegant metal structure that are the rotor hubs. Raider’s hubs are a different structural solution and fair more compactly.

I don’t think Raider is 50+ knots off it’s target speed... it was never advertised to hit the speeds of the X-2 Demonstrator. And I can think of ways that vibration can limit top speeds if the high 4P vibes leak into the drivetrain or other components that have loads that directly scale with speed. So it’s performance miss could be both drag and vibration limited. That said, it’s still a sleek airframe with one of the slickest engine installations I’ve ever seen.


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