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S97 Raider

Old 29th May 2015, 11:19
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Sultan
Show me one fact that I misrepresented. One.

Tilt rotors are faster, and more efficient in cruise than other high speed configurations. The L/D of the V22 is fine, and I bet the V280 will be even better. For that greater speed, Tilt Rotors have less payload (given the same power and empty weight) and are not as nimble at low speed. Those are facts, much as we might try to wish them away.

That being said, the V280 is a viable configuration, and a worthwhile competitor for FVL missions. The V22 is successful, and meets most of its promises handily.
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Old 29th May 2015, 14:04
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Tilt Rotors have less payload (given the same power and empty weight) and are not as nimble at low speed. Those are facts, much as we might try to wish them away.
Generically, I dont think you can say that tiltrotor payload is always less for a given power unless you specify a mission or some parameters. The ability to perform STOL maneuvers means that you are not necessarily limited to rotor/hover performance for payload calculation.

For low speed maneuverability, ADS-33 is a pretty dated spec, and new tiltrotor designs seem to have designed remedies for the V22 yaw sluggishness with much higher flapping capability.

Nick, weren't you the one chiding Weiner's team that if they wanted to hit their speed target on X2, they just needed to push it out of the ramp on a V22? But that was in your Bell days
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Old 30th May 2015, 03:49
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Sans,

I suspect when Nick is referring to lower payload for the same power and empty weight, he's referencing the higher disc loading tilt rotors have always had (at least up through the 609 and Model 916/918 aircraft). The V-22 has famously poor disc loading (wing/blade fold being a huge design driver), but even the better balanced 609 is still higher than an X-2 would typically be.

Looking at the V-280 concept art, it does appear that they are looking to improve the disc loading and thus hover efficiency over the V-22, but I doubt they will get down to ~12 lb/ft^2 like the RAIDER (and presumably SB>1).

None of the tilt rotor heads that I have experience with has a dramatically higher flapping capability than the V-22. Certainly the two production intent designs flown after the V-22 don't. So if there's enhanced low speed maneuverability, it isn't coming from there. In VTOL mode, these aircraft are very G limited vehicles until they get significantly wing borne.
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Old 1st Jun 2015, 14:27
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None of the tilt rotor heads that I have experience with has a dramatically higher flapping capability than the V-22. Certainly the two production intent designs flown after the V-22 don't.
True, I should have said "design studies". In fact, remember that 609 has no lateral cyclic flapping, and gets roll through DCP in hover and flaps almost identically to the V-22 despite not being underslung.



So if there's enhanced low speed maneuverability, it isn't coming from there.
'Sports-car' Performance Promised for Bell V-280 | Defense: Aviation International News
The Army wants to focus on low-speed agility, so the V-280 will have about 50 percent more flapping capability in its rotor system than the V-22. That’s going to enable an even greater level of agility in all axes–pitch, roll, and yaw–so that you have that sports-car type of helicopter performance in the landing zones and objective areas. That’s a focus for the Army customer.
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Old 2nd Jun 2015, 12:35
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Sans,

Interesting article mentioning the higher flap capability, I hadn't seen that one. Thanks. If the hubs still have elastomeric gimbals and CF bearings, that will be a life challenge, but rubbers are always getting a little better and the life of the demonstrator is short :-)
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Old 3rd Jun 2015, 04:00
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One major difference between the V-22 and V-280 is that all of the rotor moments/forces in the V-22 had to pass thru the gearbox structure.
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Old 30th Sep 2015, 21:16
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Now with fairings!

Saw this on Sikorsky's Facebook page... Photos of the RAIDER flying with the full set of fairings installed including the elusive fairing between the rotor heads.

https://www.facebook.com/SikorskyAir...53129023280770

Looks good!
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Old 30th Sep 2015, 22:41
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So four months to put fairings on, not impressed. I was waiting for a press release where they with great daring and skill expanded the flight envelope above 10 Knots.

The Sultan
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Old 1st Oct 2015, 18:43
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Sultan

You seem to have a big personal problem with Sikorsky, and Nick in particular. My guess is that I am not the only one on this forum getting a bit tired on this. It is one thing to be supportive for a product, but also realise that other manufactures can also build helicopters that can fly.



CB
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Old 1st Oct 2015, 19:08
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Sultan, it's a small industry, I'd keep the snarky comments down... I know other manufacturers have gone months between flights at the beginning of flight test on internally funded programs.

In the meantime, I'm quite sure they've done more than 'installed some fairings'...
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Old 2nd Oct 2015, 04:12
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Collective/Spline

From the original Sikorsky first flight press release:

Sikorsky chief pilot Bill Fell and co-pilot Kevin Bredenbeck completed three take-offs and landings during the hour-long sortie and evaluated the aircraft’s handling in all four cardinal directions at speeds up to 10kt.

“It was quite the aggressive first flight for a helicopter,” says Bredenbeck, who piloted the X2, the S-97’s proof-of-concept demonstrator.
I was mocking Sikorsky's own words about how doing ten knots was aggressive. They probably did nothing except hover over a point in a ten knot wind and do control inputs, standard but not aggressive. Typically it would be a couple of days to get to a respectable 60 knot-ish envelope to fine tune the FBW system which, with Sikorsky's PR, would have been released. No fairings needed for that. Once fine tuned, fairings would be needed to push past the speeds of a 50 year old 53. That also would have resulted in a press release. I am sure they will make their 220 knot goal, but they are 4 months into their year long program. I grant that it took Bell over two months to expand the envelope of the 525 beyond 160 knots (near design speed) with a totally new privately funded FBW aircraft, but they at least waited to annouce something announcable, Adding fairings is like touching up paint if all you are doing is hovering.

The Sultan
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Old 2nd Oct 2015, 15:45
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Sultan,

I won't try and justify the use of the term 'aggressive', though from watching the longer videos, it looks like they did more than hover over a point making control inputs. Looks like the translated in all directions and made control pulse inputs to check stability/response, etc. I agree standard stuff, though pulses aren't always on a first flight test card. To be fair to Sikorsky, they haven't even made an announcement regarding additional flights beyond a few photos posted to social media... The fairings are only a visible change.

Glad to hear the 525 flight program is proceeding... that's an aircraft Bell has sorely needed for many, many years.

SD
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Old 2nd Oct 2015, 16:34
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Originally Posted by Collective Bias
Sultan

You seem to have a big personal problem with Sikorsky, and Nick in particular. My guess is that I am not the only one on this forum getting a bit tired on this.
Indeed. I suspect that a whole lot of test points and data not widely discussed were the topic of the test, if my exposure to a developmental program about 20 years ago is any guide.
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Old 6th Oct 2015, 00:11
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CTR
 
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S-97 First Flight Rushed?

A week article today reported S-97 program manager statement that flight testing is being halted again for another 9 to 12 weeks. Reason is to wait for more hours to be accumulated on the gearbox test stand units.

It appears first flight of the S-97 followed the course of the majority of new aircraft programs. Get it in the air as quickly as possible to meet a executives milestone, just so he or she will get their bonus. Does not matter if very little real data is aquired or if the flight test schedule is actually delayed by a flight only for the press. Not picking on Sikorsky, especially not the people busting their ass getting it done. Just stating that the S-97 followed the old aerospace adage I was told 35 years ago; "First flight only has to be high enough to pass a piece of paper under the wheels". Then you push the aircraft back in the hangar and finis the job.
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Old 6th Oct 2015, 02:08
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CTR,
I am sure you are right on. I am not part of the S-97 inner circle, as I left Sikorsky when they closed Schweizer down. But your words ring with truth that I have seen firsthand before.
Bryan
Sikorsky/X2 Alumni
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Old 6th Oct 2015, 02:59
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Actually I think Sultan is suffering from a case of Intellectual Penis Envy when he opines re Nick. I suppose when he peers at his own "I love Me!" display on his Cubicle wall....he feels quite small thinking of what Nick's must look like after all these many Years in the Industry, Awards, Trophies, Patents, and the other Memorabilia he has accumulated as an Army Pilot, Engineer, Test Pilot, and Senior Executive heading up Research and Development Operations at several Aerospace Firms.

But....we should be tolerant of those fighting the Green Eyed Monster that lurks in some.
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Old 6th Oct 2015, 11:34
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I think anybody who has really accomplished something can look at the accomplishments of others and recognize that they have done something good. I am not a tiltrotor guy, however clearly they have kicked ass to get the V22 to where it is today. Why badmouth them? When I was younger I did not always behave as such, but maturity is a good thing.
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Old 6th Oct 2015, 23:41
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A week article today reported S-97 program manager statement that flight testing is being halted again for another 9 to 12 weeks. Reason is to wait for more hours to be accumulated on the gearbox test stand units.
I recall reading somewhere a comment from Sikorsky saying with the S-97 they wanted to accumulate a certain number of hours of drivetrain bench test for each hour of planned flight test. Seems reasonable given the relative complexity of the drivetrain and that it is an all new design. Being internally funded there are no contract schedule milestones to meet, and any flight test failures will reflect poorly on Sikorsky's JMR-TD effort which relies on the same technology. So Sikorsky has very good reason for taking their time getting everything right before continuing with S-97 flight testing.
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Old 7th Oct 2015, 04:31
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Rushing Flight Test

Originally Posted by riff_raff
I Seems reasonable given the relative complexity of the drivetrain and that it is an all new design. Being internally funded there are no contract schedule milestones to meet, and any flight test failures will reflect poorly on Sikorsky's JMR-TD effort which relies on the same technology.
The point is why not wait until after the required testing is complete to start real flight testing. Instead of rushing first flight to meet some artificial date for a press release.
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Old 7th Oct 2015, 18:51
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Originally Posted by CTR
The point is why not wait until after the required testing is complete to start real flight testing. Instead of rushing first flight to meet some artificial date for a press release.
I think the artificial date is for execs to get a bonus. If we could just get back to engineers running these companies then this silliness would go away.
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