• Hi Guest! Forum rules have been updated. All users please read here.

JMR (Joint Multi-Role) & FVL (Future Vertical Lift) Programs

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Lots of very careful wording there from the CEO
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
He says
Defiant will do over 230 knots, which is that threshold requirement.
Not "Defiant has done over 230 knots."


Correct me if I'm wrong, but wasn't the FLRAA threshold requirement 250 knots? Or has Army lowered the requirement to accommodate Sikorsky?
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Guess we will find out next month when the RFP drops, although I suspect it will be kept close hold.
@F-14D - I would not be surprised to find out you are right.
 

Moose

ACCESS: Top Secret
Senior Member
Joined
Jul 4, 2010
Messages
1,452
Reaction score
483
He says
Defiant will do over 230 knots, which is that threshold requirement.
Not "Defiant has done over 230 knots."


Correct me if I'm wrong, but wasn't the FLRAA threshold requirement 250 knots? Or has Army lowered the requirement to accommodate Sikorsky?
Documents before the RFI indicated 250 was threshold for continuous cruise, but we don't know what the RFI's numbers were. The max speed I've seen reported for SB>1 is 232 kts, but that was in a shallow dive rather than level cruise.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
He says
Defiant will do over 230 knots, which is that threshold requirement.
Not "Defiant has done over 230 knots."


Correct me if I'm wrong, but wasn't the FLRAA threshold requirement 250 knots? Or has Army lowered the requirement to accommodate Sikorsky?
Documents before the RFI indicated 250 was threshold for continuous cruise, but we don't know what the RFI's numbers were. The max speed I've seen reported for SB>1 is 232 kts, but that was in a shallow dive rather than level cruise.
In June of last year they hit 205 knots in level flight, which they made sure everyone knew, using a bit under 50% power. Four months late they excitedly announced they had gained another six knots, but apparently needed 2/3 power to do it. That's as fast as they've gone in level flight, and of course they haven't flown in a while.

The RFI came out in 2019 and was updated slightly, I believe, in 2020. Press reports indicate that the threshold was 250 knots. Like Yasotay said, the key will be the RFP. If they lower the speed requirement there, that would be very telling.
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
The RFP that you mention was a DRAFT RFP that they sent to industry for comment. I saw that there was something like ~1000 comments from industry (note they also had MOSA as part of the DRAFT RFP). The real RFP, that will be used for down select will be issued this June.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
I'm not sure if your comment for me, but we agree, the real RFP hasn't dropped yet, the 2019/2020 reaching out were just RFIs. What comes out next month will be the real telling document. I suspect most of it will be made public on SAM.gov, except for some classified portions. The responses, though, will be close hold until after selection is made.

The consensus seems to be that Bell would win FLRAA and Sikorsky would win FARA, on speculation that DoD wouldn't give both awards to the same prime. Maybeso, but Bell hasn't won a lot of major sales to DoD in the last 20 years or so while Sikorsky has been getting contracts for all kinds of things based on the UH-60, and DoD seemed OK with that. There also seems to be an assumption that the technologies employed by the two companies are at the same level of maturity.

The thing is, while Bell does not have an aircraft flying, a lot of the technologies come from the 525 and more importantly, they're using conventional, although advanced, technology. Sikorsky is going with a new technology for its entrant. The S-97 could be though of as a demonstrator, but it is not a prototype of the larger Raider-X, although it uses X2 technology. S-97 has not been a blazing success so far. It's been in the air for over six years and has yet to demonstrate its promised speed (granted FARA requires less speed), or agility. It took off late and kept missing goals. Only one non-Sikorsky pilot has ever flown in the a/c and the accompanying Sikorsky test pilot didn't feel comfortable enough to let said pilot have full control of the aircraft. *Explanation: There's only one collective in the S-97 and Sikorsky did not feel confident enough to let the guest pilot have access to it.

My point may be that industrial policy may not be enough. If Bell easily meets or exceeds all of its (admittedly lower) promises while Sikorsky has the same level of struggle it's had with X2 so far and its Raider-X is noticeably more expensive, the possibility exists that one prime could win both. This is Army's at least fifth attempt to field a replacement for the OH-58, and they may just want to go with lower risk.
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
@F-14D - This would be a grand discussion over beer, or bourbon. As a full on cynic of the entrenched bureaucracy that is the DoD, I am in favor of the "less risk wins" as the likely policy. So at the moment the S-97 and the V-280 have the nod for likely solutions in my opinion. I do agree that the Bell 360 has a good pedigree, but that helicopter (525) is not approved by the FAA yet as safe for the airways. There is a tie by the dim logic of the bureaucrat that both the S-97 and the 525 have pranged (tragically for 525), so a heightened risk value is assigned to both. Of course we are in complete agreement that V-280 has a fair chance (even though it is a tilt rotor and the US Army Aviation still thinks that a sort of voodoo) due to the complete success of its demonstration program, while the SB>1 Defiant has ~30 hour total time in 3 years. The cautious words of the new Sikorsky CEO are telling. They have lots of hours on X2 technology. One might argue they have years, if not decades of X2 experience. I suspect that the lack of flying by the SB>1 is not unnoticed. Bell is of course making the best of their success by pointing out they are ready to go now, with a very successful demonstrator that is a finalist for the coveted Collier Trophy. Of course they are competing against Elon Musk so the "snowballs chance in hell" analogy comes to mind.

So I think that the "likely course of action" remains front runner not for a technological reasons but more so a industrial base rational. Bell does FLRAA, Sikorsky does FARA, Boeing does CH-47 Block II and AH-64E,F,G,H... The Congressional delegations from any-state remain appeased.
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,760
Reaction score
2,079
I suspect that the lack of flying by the SB>1 is not unnoticed.

This has been a Sikorsky hallmark for years; they just don't fly their prototype/experimental aircraft very much unless they can use someone else's money to do it. Not sure why, but I don't think it's unique to SB>1.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
while the SB>1 Defiant has ~30 hour total time in 3 years
The fact they have run so much time on the propulsion rig makes me feel a lot better about whatever conclusions they are generating from that data. And the fact the Army caused the main rotor delay makes me feel better about how long it took to fly.

Bell is going to be faster and have longer legs. It's going to come down to "everything else" if Defiant is going to have a chance.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
3,799
Reaction score
2,885
I have already expressed my opinion earlier so you might not want to re-read that but to me Defiant is badly architectured with her massive Gearbox and transmission eating half the airframe volume. Moreover their traditional approach makes Defiant taller than she could be with a massive frontal section.

IMOHO, they should have buried the engine inside the fuselage volume and split the cabin in two halves with a joint section behind the cockpit. Defiant would have been more compact, less tall and the landing gear could have been more robust with less extended legs (but as much travel needed for crash safety concerns).
That could have improved the speed of the a/c and augment naturally her agility (less moment arm from reaction forces to the rotor plane).
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
while the SB>1 Defiant has ~30 hour total time in 3 years
The fact they have run so much time on the propulsion rig makes me feel a lot better about whatever conclusions they are generating from that data. And the fact the Army caused the main rotor delay makes me feel better about how long it took to fly.

Bell is going to be faster and have longer legs. It's going to come down to "everything else" if Defiant is going to have a chance.
Certainly agree that there has been much data made available using the propulsion rig, however, there are likely some vibratory loads that cannot be accounted for with the dynamic components tied to the ground. I will let those here with much better aero engineering/dynamics experience confirm or deny my thoughts.
At the end of the day I think either rotorcraft will be satisfactory for the Army. I do however think with the pivot to the Pacific longer legs and speed are going to be a critical factor.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
Tomcat said:
Defiant is badly architectured with her massive Gearbox and transmission eating half the airframe volume...
IMOHO, they should have buried the engine inside the fuselage volume
... Not sure what that solves.

There's no doubt that the necessary transmission is huge. There has to be a practical limit on the ability to scale this up (doesn't there?), but Sikorsky pitched(/is pitching?) X-2 for the JHL program as well. If the transmission doesn't set the size limit rotor stiffness and material science probably does. I'd guess Defiant is about as far as X-2 ready to be pushed in this regard, but people who are looking at real numbers seem to think otherwise.

Certainly agree that there has been much data made available using the propulsion rig, however, there are likely some vibratory loads that cannot be accounted for with the dynamic components tied to the ground
I'd suspect that is certainly true, and probably accounts for why they are beating up the power plant on the ground and using that to inform the modeling before expanding the flight envelope.
I do however think with the pivot to the Pacific longer legs and speed are going to be a critical factor.
I would lean that way, too. Based only on limited-knowledge and hunches, I'd also rather find an LZ, or drop into an LZ in close proximity to other aircraft in my flight, or get into the weeds in the Defiant than a tilt-rotor.
 

sferrin

ACCESS: USAP
Senior Member
Joined
Jun 3, 2011
Messages
14,010
Reaction score
2,432
Tomcat said:
Defiant is badly architectured with her massive Gearbox and transmission eating half the airframe volume...
IMOHO, they should have buried the engine inside the fuselage volume
... Not sure what that solves.

There's no doubt that the necessary transmission is huge. There has to be a practical limit on the ability to scale this up (doesn't there?), but Sikorsky pitched(/is pitching?) X-2 for the JHL program as well.

I thought I saw somewhere that X-2 tech crapped out at those sizes. Massive transmission or something. Yes, they initially had it but I thought I read somewhere that got shelved.

9939-90a144d0b16c880b2ef8f9a5fe218e4f.jpg
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
@sferrin - Indeed near the end of the JHL effort Sikorsky elected to go with a tilt rotor solution.

@_Del_ - On the face of it I agree with your reasoning regarding landing, but heard many a ancient Huey pilots make the same argument about the "huge" Blackhawk a number of years ago.
 
Last edited:

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
sferrin: Regarding your picture, that was one of many artists' conceptions that came out before they finalized the X2 Demonstrator. To the best of my knowledge, all depictions of X2 craft since then have always shown the cabin forward of the mast. You'll note that even in thatearly illustration of a very large craft, it looks like there are actually two cabins on that aircraft, one forward and one aft of the mast,which is rather unwieldy. I don't remember exactly where, but I do recall a couple years back Sikorsky acknowledging that X2 will not scale up much larger than FVL-Medium size and this may be why. For FVL-Heavy they were pushing something like the H-53K, and for above that they actually had kind words for Tilt-Rotor.

_Del_: RE: close proximity:

1622149044465.png

Considering how limited the envelope expansion on the S-97 has been in over six years and, after flying over a year late, how few hours have actually been flown on the SB>1 in over two years, waiting on the modeling does not fill one with overflowing confidence.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
_Del_: RE: close proximity:

View attachment 658035
It's a swell picture, but I'm not sure how well it reflects reality when the high disc-loading is throwing dirt everywhere and pilots are coping with a RVL while rounds are flying both directions.
The tilt-rotor is probably going to have a harder time coming straight up and down fully loaded than the coax design, which is going to affect minimum safe distances in some circumstances, and particularly makes obstacle avoidance a chore. Is it going to need more than a 10:1 obstacle avoidance zone around the LZ? If the V-280 is 7 meters high, you're going to want to plan a 70 meter gap for the guy behind him to clear him if he gets stuck on the ground. Maybe more for the tilt rotor. Even in a light Bell 407, you're going to want 100' by 100', for an LZ ideally. It's not just how many footprints you can draw on a football field.
I can also think of at least one instance the Air Force lost a V-22 while flying more than the 250' minimum distance requirement behind the lead aircraft with the nacelles pointed up. FLRAA will be lighter, so that will help, but it's going to be factor.

Considering how limited the envelope expansion on the S-97 has been in over six years and, after flying over a year late, how few hours have actually been flown on the SB>1 in over two years, waiting on the modeling does not fill one with overflowing confidence.
I think some skepticism is warranted, and rightly or wrongly, we are all going to be prejudiced by the slow envelope expansion.

As to the delay, I'm not sure how the customer can ask Sikorsky to pioneer a brand new process and not hand-lay rotor blades as they had planned, and also dock the contractor points because developing that process from scratch cost them a year.

I'm not advocating one over the other. I suspect the X-2 approach is superior in deceleration, hover, agility. There was never any doubt the tilt-rotor approach was going to be faster and longer legged which is also desirable. The crux will be how the Army weighs the requirements. While I suspect, like yasotay said above, the speed and range is probably going to win the day, I'm not sure it's a foregone conclusion, or necessarily the right one. It's the speaking in absolutes that bothers me.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
_Del_: RE: close proximity:

View attachment 658035
It's a swell picture, but I'm not sure how well it reflects reality when the high disc-loading is throwing dirt everywhere and pilots are coping with a RVL while rounds are flying both directions.
The tilt-rotor is probably going to have a harder time coming straight up and down fully loaded than the coax design, which is going to affect minimum safe distances in some circumstances, and particularly makes obstacle avoidance a chore. Is it going to need more than a 10:1 obstacle avoidance zone around the LZ? If the V-280 is 7 meters high, you're going to want to plan a 70 meter gap for the guy behind him to clear him if he gets stuck on the ground. Maybe more for the tilt rotor. Even in a light Bell 407, you're going to want 100' by 100', for an LZ ideally. It's not just how many footprints you can draw on a football field.
I can also think of at least one instance the Air Force lost a V-22 while flying more than the 250' minimum distance requirement behind the lead aircraft with the nacelles pointed up. FLRAA will be lighter, so that will help, but it's going to be factor.

Considering how limited the envelope expansion on the S-97 has been in over six years and, after flying over a year late, how few hours have actually been flown on the SB>1 in over two years, waiting on the modeling does not fill one with overflowing confidence.
I think some skepticism is warranted, and rightly or wrongly, we are all going to be prejudiced by the slow envelope expansion.

As to the delay, I'm not sure how the customer can ask Sikorsky to pioneer a brand new process and not hand-lay rotor blades as they had planned, and also dock the contractor points because developing that process from scratch cost them a year.

I'm not advocating one over the other. I suspect the X-2 approach is superior in deceleration, hover, agility. There was never any doubt the tilt-rotor approach was going to be faster and longer legged which is also desirable. The crux will be how the Army weighs the requirements. While I suspect, like yasotay said above, the speed and range is probably going to win the day, I'm not sure it's a foregone conclusion, or necessarily the right one. It's the speaking in absolutes that bothers me.


Here's the thing. Regarding the hand laying of blades, and the delay, keep in mind that the over one year delay was from a date that Sikorsky had said they would have no problem meeting, and then they kept missing their own revised dates. Both the X2 demonstrator and S-97 experienced flight delays as well. Also, this technology is one Sikorsky proposed, not one that the customer told them to use. After all, Sikorsky's confidence in the technology was one of the reasons they were selected over other competitors for JMR-TD And I believe that technology is already in use on other rotor blades. Plus, while the S-97 has had problems, building the blades hasn't been one of them. My personal and totally unverifiable belief is that they had control and vibration issues and used the blades as an excuse to delay first flight. Regardless of the actuality, docking the contractor points (they didn't even get into the air until after the JMR-TD flight test was supposed to be over) for delaying a program is perfectly proper. Regarding being prejudiced about a slow envelope expansion, I'd say the term "glacial" is more accurate. How long is DoD supposed to wait and why do so, especially if there are viable alternatives out there? I mean, they're waiting for further modeling before trying again? That does not argue for a smooth entry into service.


Regarding height in the LZ, I sure wish we had some dimensions published for either of these. The X2 mast looks taller, but who knows yet? The V-280 may fold up smaller, but operating? I'm not too concerned about downwash, the V-22 situation is not characteristic of Tilt-Rotors, but rather a function of constraints imposed upon the aircraft by the customer during design.

I too am perfectly willing to accept whichever is the best in the timeframe we need. As FARA shows us, there are certain lower size limits a Tilt-Rotor just can't do efficiently. Yes, there are claims that an X2 would decelerate better at the low end (if both are restricted to level attitude) and there is a belief that it might be more agile and hover better at lower speeds, but in all this time they just haven't demonstrated any of this yet . The fact remains the competing technology has met or exceeded all the requirements laid on it, while this technology hasn't. They still could pull this out, but they need to actually demonstrate, not simulate or advocate, that they can do what they claim.
 

_Del_

I really should change my personal text... Or not.
Joined
Jan 4, 2012
Messages
643
Reaction score
416
And I believe that technology is already in use on other rotor blades.
Who are the other companies with an automated fiber laying capability for something the size and complexity of a rotor blade? I know there are plenty of companies including Airbus and Boeing who are exploring different applications for AFP, but I don't know of any rotor blades being produced this way except the Boeing ones for this project. And 11 days for blade lay up is pretty impressive, now that they've got it working.

My personal and totally unverifiable belief is that they had control and vibration issues and used the blades as an excuse to delay first flight
It's a pretty elaborate hoax to spend two years trying to produce a rotor blade, then abandoning the tooling and replacing it with a different stiffer material just to hide vibration issues which everyone already suspects they will/would encounter... And I don't know why the Army would go to bat for them on the tooling issue afterward as they did.

Plus, while the S-97 has had problems, building the blades hasn't been one of them.
...
Considering how limited the envelope expansion on the S-97 has been in over six years, ...
S-97 beat the speed requirement for FARA two years ago without issue. They had an early flight control software issue which resulted in the crash in 2017 after the rotors kissed. That understandably delayed the flight test program for the other aircraft. Since meeting the goals, it hasn't flown much. They haven't shown much interest in flying on their own dime since then.


The X2 mast looks taller, but who knows yet?
Well, neither the Defiant or V-280 are completely representative of whatever becomes the final proposals. One big question mark on the Defiant is how they plan to break that puppy down for transport in a way that is remotely quick or easy.

I'm not too concerned about downwash, the V-22 situation is not characteristic of Tilt-Rotors....
It's a function of the disc-loading which is naturally going to be higher in a tilt-rotor. I do not know that it will be a problem, especially since the FLRAA is going to be lighter and smaller, but it's still going to be pushing a lot of air at high(-er) velocities than an equivalent conventional rotor. It's also going to make it louder than the compound at the same weight, and toss things around.


The fact remains the competing technology has met or exceeded all the requirements laid on it, while this technology hasn't. They still could pull this out, but they need to actually demonstrate, not simulate or advocate, that they can do what they claim.
We haven't really seen the final requirements, and the tilt-rotor is a more mature technology. None of this is completely unexepected; the Army knew that going into the competition.
 

VTOLicious

ACCESS: Top Secret
Senior Member
Joined
Nov 24, 2008
Messages
743
Reaction score
378
Tomcat said:
Defiant is badly architectured with her massive Gearbox and transmission eating half the airframe volume...
IMOHO, they should have buried the engine inside the fuselage volume
... Not sure what that solves.

There's no doubt that the necessary transmission is huge. There has to be a practical limit on the ability to scale this up (doesn't there?), but Sikorsky pitched(/is pitching?) X-2 for the JHL program as well.

I thought I saw somewhere that X-2 tech crapped out at those sizes. Massive transmission or something. Yes, they initially had it but I thought I read somewhere that got shelved.

View attachment 658023
Chop off the top rotor!
Voilà, you got a X^3 type with a conventional rotor system, less vibration, smaller gearbox, less weight, less drag and no FBW system required! At this size there is no point to go with X2 tech.
 

Attachments

  • Screenshot_20210528-071154_Chrome.jpg
    Screenshot_20210528-071154_Chrome.jpg
    203.5 KB · Views: 45

sferrin

ACCESS: USAP
Senior Member
Joined
Jun 3, 2011
Messages
14,010
Reaction score
2,432
Or better yet just ditch the transmission altogether and go with tip-burners.
 

jsport

what do you know about surfing Major? you're from-
Joined
Jul 27, 2011
Messages
2,616
Reaction score
623

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
F-14D and _Del_ - Great discussion. A great point made that the outflow is likely to be "relatively" large for the tilt rotor. By this I mean that I believe the V-280 will have something on the order of CH-47 outflow. ASSUMING all of the wonderful digital gizmo's work, the aircraft should assist the crew with landing in less than ideal visual and turbulence environments. But I would agree there will be a lot of dirty air (literally and aero speaking) in an LZ. This may not be as pronounced with a group of SB>1. However I have to wonder about the air behind the SB>1 with the double stack rotors and a C-130 sized prop going, especially when putting the prop into beta (decelerate) on short final. It may be ugly there as well. I have no doubts that the X-2 aircraft can decelerate faster than the V-280. Putting that prop into reverse (beta) is a huge reverse thrust vector. That would indeed be a handy feature. As an old assault pilot I have to say that I am not keen on the prop at the back of the SB>1 in an LZ. Corporal Murphy always show up at the worst time to make bad things worse. As to the overhead clearing point, I think it a tie really. I don't know which one is taller, but I doubt the difference is much more than a foot. Both platforms should have ample power for clearing obstacles with a full weight load at normal environmental conditions, although the larger rotor system of the SB>1 might have an advantage. Of note the FLRAA competitors have not been told what engines to use in their proposals. Also of note both platforms are capable of pointing the nose down while decelerating to give the crews a clear view of the LZ. Finally on the LZ discussion, given the drastically increased accuracy of weapons that can be brought to bear on a point in far less time, large formation landings of massed troops will likely be exceedingly rare. So the eight ship into the football pitch (a.k.a. soccer field) is likely to be equally exceedingly rare. What is more likely are "rolling" LZ where troops are deposited in consecutive LZ, assuming the terrain accommodates. If not I would expect two ships coming in from a number of directions at a time. Sure it takes longer, but reduces the chance for mass damage. Of course either way Corporal Murphy is waiting.

As to maneuverability, the V-280 has repeatedly demonstrated the required Level 1 maneuverability per the specifications. The SB>1 has not yet done so. Hard to argue against that. I have no doubt it could, but given that the JMR program is over and defunded, it will have to be on LMCO/Sikorsky to demonstrate beyond simulation. As mentioned above a nagging concern is that the first S-97 Raider did have rotors kiss, even if it was due to uncommanded software input. It is not clear to me if the incident maneuvers were grossly out of the parameters the aircraft could be expected to exhibit in combat or not. I doubt we will ever know more than the pilots did not make the inputs. This occurred on a smaller X-2 airframe. I have no expertise to know if more mass and inertia of a larger rotor system would make this more probable for larger aircraft making similar control input. I just have to wonder as mentioned above if the X2 technology is at the ragged edge aerodynamically and weight wise at this size rotorcraft. Conversely, I think the Raider X scout is going to be hard to beat, since the U.S. Army is expecting to have to cover much larger areas with the same (much reduced from cold war levels) number of scout helicopters.

As to the very large FVL (C-130 sized) X2 rotorcraft Sikorsky initially had two options. Slow and small, think H-60 sized airframe with huge rotors and huge lifting capacity and the one seen above we are most familiar with. Sikorsky pressed hard to get the Army to change the requirement (so did Boeing with a large H-47 looking proposal) so that the small lifter could compete. It had the same sized transmission we see today. When the Army made it clear that the requirements would not be reduced they went with the C-130 sized X2. The C-130 sized CONTIGUOUS cargo bay meant that a flat pack transmission (think Mi-26-like) would have to be developed. By the end of the effort Sikorsky elected to move to tilt rotor, reluctantly acknowledging that the X-2 did not seem to scale up to that size without much scientific breakthrough.

VTOLicious - As to X3. It has demonstrated admiringly the potential of this layout. I look forward to seeing how well it does with military requirements (more troop seating, more weight for armor and survivability equipment, etc.). Again my concern will be the propellers in proximity to the ground in unprepared landing areas and with mistake prone individuals milling around. I hope the plan is for both propellers to be able to be put into beta, as loosing the wrong propeller will at be at least loss of anti-torque and at worst stuck anti-torque control in the wrong direction. That said my background makes me expect the worst to always happen.

I honestly do think X2 and X3 have a place in the sun. However for the U.S. Army assault platform requirement as it stands, I have to say that the tilt rotor seems the less risky way forward given what I know. Won't hurt my feelings at all to be proven wrong.

jsport - excellent question.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
3,799
Reaction score
2,885
Basically contra-rotating rotors accelerate twice as much a stream of air compared to a single rotor. So the overpressure would be greater on the SB-1X and the risk of recirculating flows aggravated.

Regarding the rear prop Vs a winged tilt rotors airframe, the advantages are less clear than what it seems: having a wing, and depending on the amount of G the airframe can endure, the winged tilt rotor can manoeuvre to loose speed more efficiently (it can come fast, break, loose speed and transition) when a more traditional airframe would be limited by the speed to start using its main rotor for aero-braking (loose speed, engage reverse propulsion, loose speed again then pitch up).

It will depend greatly upon each airframe design. It will be hard to narrow on a configuration without seeing them both in flight.
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Of note from the Army budget: "The FVL budget request is $1.12 billion in FY22, which includes a $270 million boost for the service’s future long-range assault aircraft {my emphasis} expected to be fielded around 2030, according to Pasquarette." - "US Army’s FY22 budget backs modernization, cuts ‘down into bone’ of legacy fleet", Jen Judson, Defense News, 28 May. This is not the first time the FLRAA has had its funding boosted above the baseline. Priorities.

 

shin_getter

ACCESS: Secret
Joined
Jun 1, 2019
Messages
323
Reaction score
307
Related


From Govtribe:
Full Spectrum Targeting (FST) Payload
ParameterThreshold Objective
Size, Weight, and Power (SWaP)(1)20” outside diameter gimbal, 190lbs total weight (payload & electronics), 500W max18” outside diameter gimbal, 140lbs, 400W max
Altitude(2)≤100ft above terrainSame as Threshold
Speed≤40kts IASSame as Threshold
Target typesTanks, APCs, ADUs, support vehicles and troop concentrations. Priority is for Air Defense Units. (discriminate between real and decoy)All vehicles, dismounts, (discriminate between real and decoy combat vehicles)
Target EffectsConcealed: in/under/along canopy/foliage, in defilade, under camouflage nettingSame as Threshold
EnvironmentOpen, low to moderate competitive clutterDegraded Visual Environment (DVE) and Urban competitive clutter
Coverage Area45º in azimuth in any direction relative to the airframe(3)Same as Threshold
Timeline(4)20 secs10 secs
Probability of Detection(5)90% @ ≥12km90% @ ≥20km
Probability of Recognition(5)70% @ ≥12km70% @ ≥20km
False Alarm Rate(5)0.04 per square degree searched.02 per square degree searched

  1. The payload must be a RSTA (Reconnaissance, Surveillance, Target Acquisition) asset that provides at a minimum Full Motion Video (FMV) @ 30Hz in the RGB, Near Infrared Low Light (NIR LL), SWIR, MWIR, and LWIR wavelengths at no less than 720p resolution. It must be capable of independent pointing, 360º in azimuth and ≥+60º and ≤-90º in elevation.
  2. The payload must provide a designator class laser with both US and NATO codes and the ability to visualize designator laser spots and differentiate among multiple, simultaneous Pulse Repetition Frequencies (PRF).
  3. The payload must provide a NIR illuminator class laser which will be visible with the NIR LL camera.
  4. The payload must provide simultaneous wide area situational awareness FMV along with the RSTA FMV described in paragraph a) above, and must be day/night capable.
  5. Any other modalities and sensor systems, in addition to those described in paragraphs a) thru c) above, will be considered as long as it meets the requirements outlined in Table 1. Examples of other modalities and sensor systems include, but are not limited to, Multispectral, Hyperspectral, LIDAR, Polarimetry, and Filters.
  6. Automation is a priority. Notional, ideal workload on the operator would be a select and go function that enables automated search of coverage area at required range (w/o operator intervention), i.e. derived from aircraft position, altitude, speed and attitude. Detection results are displayed for the operator to enable an automated interrogation of the detection for recognition (if not already provided). Cross-cueing and fusion of sensors/modalities are viable options to accomplish requirements. Please describe automation approach addressing, as applicable, the use of existing AiTR algorithms, algorithm development efforts, and/or possible teaming arrangements.
  7. Operations in degraded visual environments must be considered and include localized dust and smoke as well as haze, fog, rain and snow conditions. Performance under such conditions may be estimated.
  8. Please address your approach for detection of “state of the art” camouflage. Describe, as applicable, your experience with types of “adversary” camouflage and the modalities and algorithms used to detect them.
If you ask me, it is actually kinda disappointing. Actually sending a helicopter into LOS/optical range should be a near last resort as out spotting well concealed ground forces (if you can see them, they can probably see you with similar sensor tech) is hard and the opponent may be networked in a sensor shooter structure as well, and any passive sensor could cue a brimstone class missile. When you increase you attitude for a long range look you are exposing yourself to a lot of sensors at the same time.

If the army is to have high value aerial recon vehicle I'd focus on ground observation radar and ESM and leave EOIR to attritible platforms.

Not saying that a high powered sensor is not useful, but employment would be tricky in near peer confrontations.
-------------------
On the military industrial planning that seems to underpin the FVL program: Just what kind of capability will be lacking in the future hybrid-evtol ecosystem? If well capitalized vtol firms (from civil demand) will be able to provide necessary products in the future there is no need to preserve incumbents with procurement tailored for this.

Depending on the rate of maturity of vtol tech would there a reasonable chance that existing vehicles be obsolete soon (relative to historical helicopter lifecycles) and thus a interim solution?
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
I think the requirements above are for the Air Launched Effects "disposible", not the FVL aircraft itself.
At some point eVTOL may mature sufficiently to allow for troop and/or weapon laden armored aircraft that can go meaningful distances. Just now the weight and endurance of the available batteries argue against that. I would agree though that using a turbine to create electric propulsion means should be viable in the coming years. Just because it is not front page news does not mean it is being ignored.
 

VTOLicious

ACCESS: Top Secret
Senior Member
Joined
Nov 24, 2008
Messages
743
Reaction score
378
I think the requirements above are for the Air Launched Effects "disposible", not the FVL aircraft itself.
At some point eVTOL may mature sufficiently to allow for troop and/or weapon laden armored aircraft that can go meaningful distances. Just now the weight and endurance of the available batteries argue against that. I would agree though that using a turbine to create electric propulsion means should be viable in the coming years. Just because it is not front page news does not mean it is being ignored.
That's the advantage of lift+cruise configurations. You can use a conventional propulsion (e.g. turboprop) for cruise flight and use the electric propulsion for VTOL* only. That reduces the mass of installed batteries dramatically and enables long endurance flights... Think of Beta's evtol with a turboprop installed instead of the electric cruise engine... Something like that would be a great SOFTA ;)

*only for applications without a requirement for continuous hovering.
 

Attachments

  • 20200614_140713.jpg
    20200614_140713.jpg
    294.7 KB · Views: 40
Last edited:

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
Del & Co.

Although clearly I think Tilt-Rotor is the better solution of the two in most cases, I'm not (here) trying to get into a point/counterpoint thing. my main disparagement with X2 (including Defiant) is that while there have been many, many claims, there is very little actual flight test data that backs up the promises. There are lots of, "Our simulations show...", "Our modeling indicates...", "We expect that...", as far as going out and actually doing the thing hasn't happened a lot. You can't use your own simulations as validations of themselves. I mean Bell and Airbus could claim "Our models show that the V-280 and/or X3 Racer will cruise @ M2. We proved it in simulation". The rules and laws in going into the such software should be reflect what the craft actually does, not what we want it to do. The fact that Sikorsky says it needs weeks or months of modeling prior to an hour or so of flight or to go five knots faster gives me pause. This won't fill the client with bags of confidence regarding how it'll handle unexpected situations in operation.

The flight control system seems hideously complex. As Vertical Magazine discussed in their article on the NTSB report on the S-97 crash/hard landing: "...the Raider has three flight control modes, referred to as paths: a fully-on-ground path, a fully-in-air path, and a transition path. If any one of the aircraft’s three wheels are on the ground, the on-ground path is engaged. If all three wheels are off the ground for more than three seconds, the helicopter switches to the fully-in-air path. The two are blended during the transition from air to ground, or ground to air. During the three seconds after the last wheel touches off from the ground, or 0.5 seconds after a wheel touches the ground, the flight controls are in the in-transition path". Oh, and when in transition mode the cyclic is 2 1/2 times as sensitive as it is the rest of the time. And this is if everything is going right. Does that sound like something that's ideal in a combat situation when the crew is already in a task intense situation?

My point is that if X2 is really as ready for prime time as is claimed, then show it. Actually meet some of your own promised goals and do in it a time frame that you can predict. The purpose of the exercise is to provide a craft for the Army, and probably other,s not an ongoing research program. We have one technology that should be able to meet the need. It would be nice to have another, but barring some rapid change in the situation is the other technology significantly better to be worth waiting for an indeterminate amount of time?

Yasotay: Has SB>1 flown four more hours this year? Last I heard that as of the end of 2020, they had 26 hours over 31 flights achieved by last October. Haven't heard much since. Regarding the lots of hours on X2, IIRC, except for newly built ones, every single modern Tilt-Rotor airframe has more hours on it than all the X2s ever built combined; I'm not counting the old XV-3, but even it had 125 flight hours and upwards of 250 flights.
 
Last edited:

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
To my knowledge SB>1 has not flown this year. Hours remain ~31
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
She's a tall girl... I guess that what they are all thinking.
Here's a shot of the V-280 with some folks. I post it for height comparison. The bigger thing to me is not so much how tall the two are fully ready for flight, but how big they are when folded up. This is of vital importance to USN and USMC. Bell has illustrated that a ship-based Valor would fold up in all three dimensions to the size of a folded UH-1Y. Except for showing animations with the rotor blades folded to the rear, Sikorsky has not addressed this. I don't know if they've ever even discussed reducing the height of the mast when the craft is stowed.



1623131880545.png
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
3,799
Reaction score
2,885
The slight difference comes with their respective ferry range: while Valor can relocate by itself, I have a hard time thinking that SB-1 can fly 1500Nm without being inside a cargo bay.
Hence, folding is less critical with the tilt rotor and doesn't involves gears and shaft (presumably, the wing is unbolted as a single element).
 

yasotay

ACCESS: Top Secret
Top Contributor
Senior Member
Joined
Oct 19, 2006
Messages
2,645
Reaction score
1,067
Fitting in a C-17 remains a requirement. Neither platform appears to have a solution within the parameters the Army is asking for. It appears both will have a level of disassembly necessary to accomplish this task.
On the topic of maintenance, the Bell aircraft can tilt the transmission down for work. I suspect that the SB>1 will require the a larger crane, to remove the transmission, than the one currently in Army Aviation inventory.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,810
Reaction score
270
IIRC, fitting inside a C-17 without major disassembly is not a requirement for FLRAA. I suspect that one of the reasons for the long ferry range specified is the feeling that with these technologies, if you don't have the time to deploy them by ship, you fly them where you want them to go either by island hopping (the specified ferry range just gets you from the West Coast to Hawaii) or AAR if so equipped. If the craft has major damage and you want to get it to a repair point faster than by ship, then you don't mind disassembling it anyway. Again, Bell says that if you're willing to pay for it, they can get the V-280 to fold into the cube of a folded UH-1Y without disassembly.

FARA, OTOH, does require that the craft be foldable into a C-17
 
Last edited:

Similar threads

Top