FLRAA speed requirements lowered to 230 knots?
 

Honestly, other than that Sikorsky press/media day, I can’t find an official looking requirement for 230 knots. Everything I can find says 250 knots as a threshold speed and 280 knots as objective. Has the Army given them a lower bar to clear?

Defiant at 211 kts s&l, 232 in a descent, 2/3 prop torque.
https://news.yahoo.com/amphtml/sb-1-...131114297.html

Thanks IFMU,

In the article text was my earlier question answer:

”WASHINGTON — The Sikorsky-Boeing developed SB-1 Defiant coaxial demonstratoraircraft hit 232 knots in a descent, and 211 knots in straight and level flight, meeting the U.S. Army’s speed requirements for its future long-range assault aircraft it plans to field by 2030.”

However I believe any new lower speed requirement of 230 Kts would be in level flight, not in descent.

At 2/3 power and 211 kts S&l, I'd project 258 kts max s&l.

Interesting extrapolation using only one data point.

Lets establish a curve based upon Sikorsky's own statements:

https://www.janes.com/defence-news/n...5-kt-in-flight



https://www.defensenews.com/digital-...hits-230-knots


So that's 205 kt @ "less than" 50% power, followed by 211 kt @ 66% power, which would yield a best case blistering 224 kt at MCP (empty)

And 4 months to go 6 knots faster. So basically at this blistering pace of development we can expect MCP in 8 months.

So - you are using a linear relationship between power and speed? Care to explain?

My quick estimate was by the square root of the increase of power. Also how do you know the weight? Any flight test program I've been involved with at Sikorsky has never been anywhere near empty weight.

IIRC you said you were a key player on the X2, which means you know the effect weight has on speed for an X2 rotor.

Edit: my bad, you said you did a bit on X2. So maybe you don't know.

I don’t really think the data from press releases is sufficient to build any sort of credible speed-power polar, even for trash-talking purposes. The time required to advance another 6 knots is a legitimate issue, though. Makes me wonder if the 205 knot speed claim earlier was actually in a descent as well.

I agree on all points here.

You're right. Assuming linear was probably being generous on a fuselage+rotor like SB1.

https://iili.io/3HsAZJ.png

Even the hotrod low drag/FE X2TD fuselage power required slopes up with airspeed on the upper end of the envelope

Most definitely not a key player on X2. However I do have a copy of AGARDograph 197 on my desk at the moment.

Fascinating discussion so far; there's something in the Defense News article that puzzles me: "...232 knots in a descent, and 211 knots in straight and level flight, meeting the U.S. Army’s speed requirements for its future long-range assault aircraft..."

How does "...232 knots in a descent and 211 knots in straight and level flight..." meet FLRAA requirements? Am I missing something"?

It doesn't and to Lockheed's credit, I don't think they have officially claimed it does, but some journalists have gotten "excited" about the 232 knot value.

Defiant Total Flight Hours?
 

Has Lockheed or Boeing recently advertised how many total flight hours the Defiant has accumulated to date?

i read 23 hours in one of this week’s articles.

23 Flight Hours in17 Months?
 

Thank you SplineDrive for the information. But is that information from a recent press release? It’s been 17 months since first flight.

Actually, in three days it'll have been 19 months. On August 28 SansAnhedral posted a quote from Graham Warwick (a reliable source) indicating that SB>1 had flown 20 hours. So given the nearly two months that have elapsed since then, three more hours would be in line with its average flight rate (actually it's somewhat better than their average rate) since first flight.

From above article:

Again the PR department falls down, in what world is 205 kts close to 230? Time to rename the Defiant BS-1. Also, in one of the articles it’s claimed they fly on average once a week, so 16 flights since the June 205 knot flight if they are to be believed.

With the four months between press releases I have pondered what serious problems are crippling the program. When one of the pilots commented that the June-ish test card called for a 30 degree bank, but they did 45 degrees instead I suspected flight control issues (no competent flight test pilot would intentionally miss the targeted bank angle that much). Four months is about right for a flight control software mod so that accounts for one of the claimed sixteen flights. We know the S-97 top speed has been reduced to the 180 to 200 kt range by excessive drag and brutal vibration. It is a safe bet one or both of these are issues they are having to address as they are minimizing the FLRAA requirements to avoid outright cancellation.

Any one want to give odds on another press release this year?

Actually Sultan, maybe we should be giving props to the PR department rather than denigrating them. Their job is to promote the company's interests and put the best spin on what's going on. Their job is to keep accomplishments in front of the audiences' and customers' eyes. They really haven't been given a lot to work with here and so they're doing the best they can with what they have.

Put me down for another press release in mid-December highlighting the hundreds of ground turn hours accumulated on the test beds and "thousands" of hours of simulations in various integration labs as totally validating the design. Probably a mention of a 220 knot level flight achievement, too. Unless of course, the Army lowers the FLRAA requirements further, in which case we'll hear breathless claims of meeting all requirements and being the next step in Army aviation.

Spline,

Current progress would indicate 214 knots by end of the year. As you are aware they have gotten all of the easy knots. Bell is probably in a similar position on the V-280 except their baseline is starting at 300 Kts+.which they reached a long time ago.

One minor note, unless I'm misunderstanding your context: Bell's promise was 280 knots (hence the name of the craft). They made that some time ago, and have since gone well beyond to over 300 knots.

I guess “imminent” is longer than three months.

https://verticalmag.com/news/defiant...lestones-2020/

More gaslighting from the Sikorsky-Boeing PR team. Apparently their definition of roaring through milestones are:

1. Flying only 26 hours in 20 months at the most benign gross weight/cg.
2. Achieving a pathetic top speed in level flight of 211 knots against an original target of near 250 knots (later reduced to 230 knots which they still could not achieve).
3. Not flying any gross weight/altitude/range expansion flights.

They also state the team is putting "the final touches on an official pitch to replace the U.S. Army’s long-serving UH-60 Black Hawks." So they admit they have completed all they can do with the SB-1, even though they were given a govt funded one year extension to the FLRAA demo program deadline to try to make it appear they were a viable alternative to the 300Kt++ Bell V-280, It appears their plan is to lobby the Army to water down the FLRAA speed/range requirements so much that even the SB-1 could meet them. If that fails I expect them to no bid the program and try to get FLRAA cancelled because there are not two competing for the development contract.

Well, I was too optimistic when it came to predictions of last quarter progress for SB>1. I’m sure they’ll declare success if they ever reach 230 knots, but success should be measured against the engineering performance targets, which were well in excess of that. If Defiant can’t reach their intended design Vh by the next contract phase award in March, why should they get money to continue? Two years to not reach Vh is more than enough time. Raider hasn’t made Vh in 5.5 years of flying.

Doing the Math
 

Interesting that despite the S-97 being promoted as a test bed for it’s bigger brother the SB>1, it has only accumulated 93 flight hours. So the two X2 technology aircraft combined have only 119 flight hours, compared to over 200 hours on the Bell V-280.

I fear that politics and the changing world post COVID may make a bigger difference in the future of FVL than the obvious technical maturity benefits of the V-280.

Let us all hope that sensibility and trust in science prevails in 2021.

Rather worryingly it appears that sensibility and trust in science took a precipitous nosedive in 2020. I'm certainly with you in your hope but extremely worried about what will actually happen.

Fact is that reality is what Washington decides it is.
I just see two very expensive, very large bits of complex gear, neither of which appears fit for the purpose. They are too big to do recon and too fragile to do combat.
The idea of helicopters massed to defeat tank armies is dead as a dodo, as was demonstrated in the recent Armenia/Azerbaijan war.
Aging a dumb idea does not make it smarter.

Both the SB>1 and the V-280 primary mission is troop transport. As long as soldiers need to get in and out of battle, this mission is not going away.

The Raider and Valor (correction Raider-X and Invictus) are being designed for recon and attack. I concur, that mission may soon be made obsolete by unmanned technology.

[QUOTE=CTR;10958698]Both the SB>1 and the V-280 primary mission is troop transport. As long as soldiers need to get in and out of battle, this mission is not going away.

The Raider and Valor are being designed for recon and attack. I concur, that mission may soon be made obsolete by unmanned technology.

No biggy, but you mean the Raider-X and the Bell 360 Invictus (hardly an easy-to-remember name)
I can't post URLs but like how the V-280 Valor transport flew autonomously in December 2019, the B360 will be built to accommodate pilot-less flight.

Thanks for the correction
 

Thanks for the correction. Should not reply to post after a long New Year’s eve. :-)

The mission isn't going away but the question remains if they are not too expensive/complex, too big and too fragile for the mission.
The big plus of the Blackhawk for this mission is that it is extremely rugged, rather nimble and small and not excessively complex and expensive. Almost the opposite of the new vertical lift high speed platforms. The most dangerous phase for the helicopter in combat has historically been the landing/de- boarding phase. And that is the phase where especially the valor is a huuuuge and beautiful target with lots of critical parts widely spread and is also rather limited in its agility and descent rate compared to the nimble Blackhawk. I'm not really convinced that they are not going to cancel the current bid. For certain special missions the new platforms surely offer very interesting possibilities but I have a hard time to figure them as real replacement for the rugged 'bread and butter' combat mule that is the Blackhwak.

Both FLRAA competitors have agility requirements at the LZ similar to the UH-60 platform and the V-280 has demonstrated that capability. It also has the ability to rapidly drop from cruise to LZ and back to cruise again. Conversion isn’t a long, involved process and can be done in as little as 12 seconds on other tilt rotor platforms. The V-280 is a larger target than a H-60, but it’s exposure time near the LZ is less than an H-60 and widely separating critical components is an important aspect of system design.

Fact is, the H-60 cannot do the missions the Army has envisioned for FLRAA and a tilt rotor can. Of course, this is the SB>1 thread, so we should mention that vehicle, which in nearly two years of flying hasn’t reached Vh, so perhaps it’s not well suited to the missions, either.

Sorry, but this has been shown in flight testing to be demonstrably false.

Of course, Sikorsky also claims the same thing with Defiant, but over 5+ years of trickled flight testing neither it nor S-97 have demonstrated anything approaching even what the V-280 has done in YouTube videos or in front of public audiences.

Defiant X
 

Welcome to the Defiant X


cheers

Defiant X article.

https://verticalmag.com/news/defiant...ce-black-hawk/

From the article:

While this may just be the article's author cherry picking past articles it confirms that SB has not released any updated information since June 2020. This seems to confirm no progress or flights (?) in six months. So what is wrong. If it was just drag keeping the top speed low they could have flown it to expand the GW/CG and ALT/TEMP envelopes which would gather meaningful data for any proposal and padded the flight hours to look less than the pathetically low 26 hours. I believe the demo was suppose to be at least 100 flight hours with the 280 demo ship good for at least a 200 flight hour campaign.. Giving up in doing anything since June when they needed to make substantial progress to even be a dark horse alternative to the 280 if Bell stumbled (which the Bell team didn't) points to a flight safety issue (or issues) that could not be overcome. Many have speculated high vibration, but in my experience pilot bonus money overcomes that issue. So we are looking at loads so high that catastrophic failure within a limited number of flights could occur or a danger the rotors could collide like what was already demonstrated on the S-97. It will be interesting to find out what metaphorically killed the SB-1 prototype.

Looking back at this thread, there were some flights between summer (20 hrs) and October (23 hrs), and a few more at the December (26 hrs) articles. None in Jan so far. So it’s not quite as bad as “Giving up in doing anything since June” but definitely as sign that something isn’t well. We can all speculate, but there are several likely issues, some of which you’ve identified. In any case, it’s ballsy to ask the USG for billions to develop a production aircraft based on two demonstrators that, if we’re being honest, haven’t met their design goals. There is something wrong with the aircraft concept, the design execution, or both.

As for Defiant-X, the RAH-66 exhaust is interesting... that’s a lot of mass flow in some long ducts. The hubs looks radically smaller than on SB>1, though their success in sweet talking the Army down on speed would allow for lower hub loads and smaller structure. Or it’s just fanciful artwork.

Whatever the SB-1 situation, the mission the Army envisions may also be less than realistic. The US Army has a history of poorly conceived requirements, which have resulted in very expensive but only marginally useful hardware.

Spline noted:

You are correct I falsely attributed the 211 knots speed to the 205 kt June press release. I am sure the customers have taken note of the great advancements made from June to October. Now the question is what did they do from October to December. In one article they stress how great the Defiant is at sling loading and that tilt rotors have minimal sling loading capability. Have I missed a video of Defiant with a sling load? I saw the 280 sling load demo and know the V-22 has a very significant high speed sling capability. In fact the V-22 sling speed capability exceeded a Humvee’s ability to withstand it. If SB is betting on slinging as a winning differentiation between Defiant and the 280 they are definitely on losing path.

So, according to FlightRadar24, V-280 (N280BH) is back in flight status having gone out for flights a couple of times this month. Still nothing on SB>1 (N100FV). Are there even any rumors that Defiant is still flying? Or is she grounded and done, never having reached Vh? If so, that’s a worse miss on cruise speed than Raider. Wonder what they’re doing different for Raider-X?