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

sferrin said:
The AH-56 also had a stiff, hingeless rotor, and I don't recall hearing it had an issue with vibration.
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AH-56 was stiff in plane and “hingeless” but still had flapping compliance. Its rotor is about as stiff out of plane as the Bo-105 or Westland Lynx. First flap mode is something like 1.12/rev or so (Lynx is 1.09). The Sikorsky ABC/X-2 aircraft have out of plane stiffnesses on a whole other level. First flap is in the range of 1.4 to 1.5/rev depending on model and while those numbers don’t sound very far apart, they’re hugely different.

AGARD-AG-197.pdf

If you want some not-so-light reading on hingeless rotor systems, this NATO AGARD paper is still a good resource as it surveys research efforts across a range of companies. This paper indicates the AH-56A has a flapping limit of around 4 degrees, on the same order as a Bell stiff in plane flapping flexure hub and some others. Definitely is classified as "soft out of plane". The ABC/X-2 rotors, aside from some early Hiller coaxial designs and the early Bendix coaxial helicopters, are really the only stiff out of plane models... note that none have ever gone into service. The Hiller X-2-235 (coaxial rigid two bladed rotor system) reportedly shook so badly, the government elected not to risk their wind tunnels testing it when it was donated to them. So 3, then 4 blades, does represent progress, I suppose.
 
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e-Graphite said:
It’s the lack of flapping compliance or hinges that causes the huge vibration. It’s fundamental to the design. While they need to have a stiff out of plane rotor system to limit flapping and keep the rotors separated during forward flight, normal once per revolution flapping isn’t the only out of plane motion a blade wants to go through. There are twice per revolution, thrice per revolution, and so forth and so on motions that the blades want to go through due to harmonic air loads. As the harmonic number increases, the magnitude of motion/load generally decreases. Not having a flap hinge means these motions turn into vibratory load and get transformed into airframe vibrations based on the number of blades. So a four bladed rotor has four per revolution vibrations in the airframe.

This is actually why Raider and Raider-X have four blades per rotor… this was an attempt to improve the horrific vibrations of the XH-59A which had 3 bladed stiff out of plane rotors. That aircraft shook so badly pilots had trouble reading the instruments. Adding a blade raises the frequency of vibration and reduces the magnitude. Better would be 5 or 6 blades at the expense of weight, cost, and drag… if the ever more slender blades can be made stiff enough to keep from intermeshing.

All edgewise flow rotors see an infinite expansion of harmonic air loads (though with generally decreasing magnitude). The interaction of the two rotors can certainly make them larger, but a rotor in isolation will also experience harmonic loads. This is why rotor designers must tune the rotor system to not amplify these loads, or do so as little as practical. Good tuning doesn’t make the problem go away, but it does keep them from getting amplified.
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I'd go with 5 or 7 blades, spun at lower RPM because you have additional wing area. Prime numbers help stop weird harmonic vibrations, it's why the 11-bladed props for the PT6/King Air exist.

Though for the FARA, you're already limited to a 40ft rotor diameter, so I'd probably just add the extra blade(s) and not bother with lower RPM.
 
There is always going to be multiple friction points between the services and with industry. As mentioned, the services will naturally prioritize their needs over joint. The service bureaucracy alone make change and "new" methods exceedingly hard to implement. The USAF Chief of Staff, has declared war on his own internal bureaucracy. I wish him luck.
Industry of the military industrial complex have no incentive to go universal. In the US, car dealers don't make money off of selling you a car, but on the maintenance package that goes with it. The Apache takes years to fully integrate all of the code changes. That process alone is expensive, and subject to change.
There are other issues that have to be considered as well. Few aviators are keen to come to work and fly the same aircraft that went from ver.1.2034 to ver. 1.2035 overnight. They prefer someone to have actually flown at least a few hundred hours to make sure all the code plays nice. Most gamers out there are familiar with the frequent "patch to the mod" with computer games. Learning that turning on the landing light causes the aircraft to flip over is not appealing. Apache pilots with thousands of hours in AH-64D, still have to go through schoolhouse training to fly AH-64E. No new rotors or engines. No new weapons per say. Lots of software and interface changes.
MOSA is the right way to go. The second and third order effects of making the concept a reality will be the real challenge. Hopefully the Gen X and Z folks matriculating into leadership in government and industry will find a means to change the environment.
 
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Just as a reminder: MOSA was all about non-propriatory high level language. It as been part of software/hardware codding since its inception. I doubt then that Gen X or Z that crave for Apple and the like or think that Microsoft is a cool company will fare better than other Gen previous them.

It's a systemic approach that is needed... In other words, actions from people that are not in the fashion-codding industry.
 
Dueling MOSA articles/adverts -

breakingdefense.com

Sikorsky’s RAIDER X digital backbone drives success for the Army’s Modular Open Systems Approach - Breaking Defense

Sikorsky's RAIDER X is designed to meet the U.S. Army's Modular Open Systems Approach standards for the Future Attack Reconnaissance Aircraft competition.
breakingdefense.com breakingdefense.com

breakingdefense.com

For Future Vertical Lift, FLRAA’s digital backbone will also underpin FARA - Breaking Defense

Different on the outside but with commonalities on the inside, the Army’s Future Attack Reconnaissance Aircraft (FARA) will share a MOSA backbone with the Future Long Range Assault Aircraft (FLRAA).
breakingdefense.com breakingdefense.com
 
HaveVoid said:
breakingdefense.com

Army cancels FARA helicopter program, makes other cuts in major aviation shakeup - Breaking Defense

In addition to halting the FARA competition, service leaders want to end UH-60 V Blackhawk production, postpone moving the Improved Turbine Engine Program into production, and phase out legacy drones.
breakingdefense.com breakingdefense.com

Sad to see it end like this for FARA - I’d hoped that third time was the charm after Comanche and Arapaho.
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Agreed. I still think the Army needs a drone wrangler like the Comanche or an armed tiltrotor.
 
An armed FLRAA seems likely. But the Army's preference seems to be for UAS/ALEs which can be launched by anything rather than buying a dedicated drone wrangler.
 
yasotay said:
There is always going to be multiple friction points between the services and with industry. As mentioned, the services will naturally prioritize their needs over joint. The service bureaucracy alone make change and "new" methods exceedingly hard to implement. The USAF Chief of Staff, has declared war on his own internal bureaucracy. I wish him luck.
Industry of the military industrial complex have no incentive to go universal. In the US, car dealers don't make money off of selling you a car, but on the maintenance package that goes with it. The Apache takes years to fully integrate all of the code changes. That process alone is expensive, and subject to change.
There are other issues that have to be considered as well. Few aviators are keen to come to work and fly the same aircraft that went from ver.1.2034 to ver. 1.2035 overnight. They prefer someone to have actually flown at least a few hundred hours to make sure all the code plays nice. Most gamers out there are familiar with the frequent "patch to the mod" with computer games. Learning that turning on the landing light causes the aircraft to flip over is not appealing. Apache pilots with thousands of hours in AH-64D, still have to go through schoolhouse training to fly AH-64E. No new rotors or engines. No new weapons per say. Lots of software and interface changes.
MOSA is the right way to go. The second and third order effects of making the concept a reality will be the real challenge. Hopefully the Gen X and Z folks matriculating into leadership in government and industry will find a means to change the environment.
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x2 on this post

We have a long way to go - including the depressing posts that industry thinks MOSA compromises their IP - when if its executed well, it preserves the IP of the people developing the pointy bits, while reducing integration time/costs.

In an ideal world - if the interfaces are written correctly - the latest sensor-ball should be as simple as swapping out the plugs in the front end. More dramatic changes may cause a 'window' in the weapons control system to change, but shouldn't force anyone to requalify their flight control laws. The challenge is that weapons system integrators have no contractual incentive to make this process straightforward, or introduce seven competing standards.

Govt has some hard work ahead - as it needs to sit down and define these interfaces properly, which is a different skill than standard gov contracting activities.
 
Moose said:
An armed FLRAA seems likely. But the Army's preference seems to be for UAS/ALEs which can be launched by anything rather than buying a dedicated drone wrangler.
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Then every aircraft will have to be able to be a drone wrangler.
 
I'd have to assume that the AH-64, despite the multiple upgrades over the years, still requires a lot of attention by the pilot and CPG to perform its mission meaning the crew can only devote so much attention to whatever local drones are doing. I'd also assume that a newer design like one based off the Bell 360 or Sikorsky Raider X would put less workload on the crew and give them more time to do those sort of tasks.
I yet again have lost faith in the guys making these decisions though. The Army was telling us as late as December of last year that FARA was their number one aviation modernization priority and now they pull a complete 180 two months later? What sort of UAVs are they expecting to fill those role? The "UAVs will do the job better" statement was made back in 2003 when the RAH-66 Comanche was canceled. Admittedly drones have come a long way since then, but in coming years we are going to see a rapid proliferation of counters to the sort of small disposable drones that pollute the battlespace above Ukraine. I simply think this decision is not accounting for all of the unknowns in the near future.
I know there are many critics of Sikorsky's X2 type configuration out there but I think it must have some potential to have made it this far. If the Raider X was selected I can't help but imagine it would have had a lot of potential for use with the special forces types.
 
Colonial-Marine said:
I know there are many critics of Sikorsky's X2 type configuration out there but I think it must have some potential to have made it this far. If the Raider X was selected I can't help but imagine it would have had a lot of potential for use with the special forces types.
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When this history of this era is written, I think people will be shocked at what happened at Sikorsky and X-2.
 
Colonial-Marine said:
I'd have to assume that the AH-64, despite the multiple upgrades over the years, still requires a lot of attention by the pilot and CPG to perform its mission meaning the crew can only devote so much attention to whatever local drones are doing. I'd also assume that a newer design like one based off the Bell 360 or Sikorsky Raider X would put less workload on the crew and give them more time to do those sort of tasks.
I yet again have lost faith in the guys making these decisions though. The Army was telling us as late as December of last year that FARA was their number one aviation modernization priority and now they pull a complete 180 two months later? What sort of UAVs are they expecting to fill those role? The "UAVs will do the job better" statement was made back in 2003 when the RAH-66 Comanche was canceled. Admittedly drones have come a long way since then, but in coming years we are going to see a rapid proliferation of counters to the sort of small disposable drones that pollute the battlespace above Ukraine. I simply think this decision is not accounting for all of the unknowns in the near future.
I know there are many critics of Sikorsky's X2 type configuration out there but I think it must have some potential to have made it this far. If the Raider X was selected I can't help but imagine it would have had a lot of potential for use with the special forces types.
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I would just like to see some hard data that backs up the claims of UAS superiority. They are loosing thousands of UAS a month, in the war in Eastern Europe, while people point at six videos a day of success as the demonstration of validity, even though some of the videos clearly show environmental conditions not current. I have not seen one UAS video in a rain or snow environment (not that that happens in Eastern Europe). How many successful missions are completed for the lose of thousands. Pundits and arm chair experts alike like to point to ~230 lost helicopters over two years of combat as being demonstration of not being viable any more. Yet no one has produced any useful data. If you are loosing a helicopter every 10 sortie, that is bad. If you are loosing a helicopter after hundreds sortie in a war that is to be expected. Also both sides are using antiquated technologies and/or techniques. How many of those lost helicopters were caused by controlled flight into terrain, vice enemy activity? Flying only during the day, at altitude with non-functional survivability equipment in major combat operations is not a good idea. Popularist analysis does not stand up to good analysis, but no one wants to provide the data, so the pundits and arm chair analyst get to espouse their YouTube and "X" findings.
 
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So what if they are losing 1000s of small quadcopters? Look at what the cost of each is vs a single helo + crew.
 
sienar said:
So what if they are losing 1000s of small quadcopters? Look at what the cost of each is vs a single helo + crew.
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...and vs tanks or especially infantry, those clearly don't die. It's ultimately a price of doing business, and no, drones don't replace any of it(especially smaller effector types, which aren't even competing with helicopters anyhow - but are being integrated with them instead). To be honest, it seems like some weird world of mirrors, where everyone sees only what they want to see.

Light/attritable drones don't have the capability, heavier ones are just as expensive and as of yet suffer completely unacceptable attrition.
If anyone was completely thrown out of the combat zone - it's bigger drones, not helicopters.
If anyone got disrupted by drones - it's SHORADs(threatening helicopters), not helicopters.

Helicopters somehow have eaten one certain offensive last year, proving decisive, yet this of course doesn't make for a pleasant video in TWZ article. More crucially, helicopters operate just fine in the most saturated IADS environment possible (in fact it's the environment that suffers, and it's up to a debate if in any other scenario there even will be capacity to sustain SHORAD losses as it happens in Ukraine).

If anything, Pacific fight will not have anywhere close to the density or capability (unless you're trying a helicopter assault on a deck of a destroyer); but all the restrictions on drones, especially larger ones&those capable of close-in recon, will be there.
 
sienar said:
So what if they are losing 1000s of small quadcopters? Look at what the cost of each is vs a single helo + crew.
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War is a very risky business. What if the weather does not let your thousands of UAS fly (physics suck) and the reconnaissance mission does not get done and the offensive drives into an ambush because there was nothing to see over the trees? How many lives then? I am not going to say that quadcopters are not a good addition to the tactical fight, but to wholesale throw out a reconnaissance platform designed to do the mission in all but cyclone conditions is exceedingly short sighted (not the words I would really like to use).
Quadcopters don't know commanders intent when their communications are broken, in fact they usually flutter to the ground.
A trained helicopter crew who knows Commanders intent can actually go and land and tell the Commander in person what they saw.
Quadcopters do not do well in rain and snow and can't see far in low ceilings and fog, and there reconnaissance time is in minutes not hours.
Manned platforms have the means to see through the weather that they can fly in. Been there, done that.
I am sure that a capable UAV could be developed that is almost as good as manned platforms (i.e. UCAR), but they are as expensive as manned platforms and take more people to operate/maintain. Oh and they still don't land next to the commander to report when the electronic warfare environment cuts their links.
So for want to save aircrews (who know what they are signing up for from the start) the "YouTube experts" and "armchair pundits" are willing to risk battalions of men and women.

Clearly I have a bias, but I have experience with both. We are a very long way from UAS that can do the mission as well as the purpose build war reconnaissance helicopter with trained aircrews.
 
I don't see how manned helicopters are better at recon in poor weather than unmanned ones, except you loose 100+ kg of payload? If optical observation is obstructed due to weather than the recon platform just have to get close and be inside weapons envelope of a lot of weapons, and enemy networking means degraded opponent sensor performance doesn't matter that much, and manned helicopters have far bigger sensor signature than all ground based passive sensors.

Disposable air vehicles can conduct recon in any conditions that flight is possible. Survivability is not needed, recon by explosion is functional. The real restriction to poor weather flight is a problem about engine power and range, both relatively cheap problems. The other thing is that micro aerial vehicles can simply land in enemy territory and work as a grounded sensor as long as radio relay is available, so even flight is not necessary. Alternative you can shoot ground sensors out of rockets and artillery shells and so on so you can have recon even in a tornado.

If you want to use a high performance standoff sensors off an actually survivable platform, put it on an airplane that can actually be stealthy, have mobility and low cost for payload. You can still fly low and utilize the horizon to avoid opponent long range ground based sensors with an airplane, and with modern computing you don't need to stare and eyeball the battlefield to figure out what you are looking at, take a snapshot and the computer can stitch and figure out what's been seen, and the army of analysts at base can look at it too. With an airplane you are not sticking out to any look down radar or hunted by low performance BLOS SAM like 538 which iran is busy exporting to every rebel group in its block.

Of course horizon as means of defense doesn't mean very much if both sides have spam of micro aerial vehicles looking down at everything. One common sight of the Ukraine conflict is drones looking down on various helicopter operations and use of drone radio relays to extend communications beyond light of sight, all the way to enabling FPV to fly into tunnels.

One alternative line of thinking is on the reliability of a 100+ kg radio system. Ultimately functional high bandwidth communications is better for coordination than "edge information processing" with face to face talk communications. I don't see how EW can work on standoff sensor platforms if counterbattery exists since the power equation is just awful for EW here. For penetrative missions, EW can work but you'd want an airplane for that role.

Now, there are times where manned helicopter may still be suitable. However how much of an advantage is it to develop a dedicated platform for this? Even with a dedicated platform it is not going to be mobile enough to avoid missile fire or stealthy enough to avoid detection by major threats. The main means of survivability is permissive environment, and if that can be ensured than you can just have a sensor pod that can be put on a utility heli and not lose much performance. The difference between helicopters with regard to survivability is like arguing how 36 knot speed make a ship meaningly more capable than a 28 knot ship today.
 
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It's easy to go down the rabbit hole in a debate and begin to defend a position one does not necessarily start with.

I think it's safe to say that a manned dedicated platform will outperform an unmanned asset with current technology. But this kinda remind me of the f-35 vs A-10 debate. Yes there are scenarios A-10 will outperform (even significantly) the f-35. But it's not about effectiveness it's about weighing the cost and risks. Can a combination of different assets provide an 80 percent solution without the cost both in term of capital and human lives? If so then the next question would be is it easier to figure out ways to offset that last 20 percent difference than to correct the flaws of that 100 percent solution, and are technologies heading toward the direction of offsetting that 20 percent difference or toward correcting the flaws of legacy solution?
 
I agree that it is unlikely that we are going to persuade anyone that their position is incorrect. I do know that the UCAR effort to design a purpose built uncrewed scout helicopter was cancelled because it would cost as much as, or more, than a manned platform and required a third more people to manage and operate.

That said, some metrics below:

"As a general rule, to ensure safe flight, the wind speed should be two-thirds or less of the drone's maximum speed. So if a drone can fly at a maximum speed of 18 miles per hour (mph), it is advised not to fly in wind speeds exceeding 12 mph."(dronesurveyservices.com)

"The DJI Mini 3 drone is engineered to withstand wind gusts up to 10.7 m/s, which equates to about 24 miles per hour,"(dronesurveyservices.com)

"A sunny day with low winds is ideal for drone flying."(Rockrobotic)

The only wind limit for military helicopters (other than severe turbulence) is the not to exceed wind speed for starting the aircraft. This is usually between 30 and 45 knots, with larger rotorcraft able to withstand the higher wind speeds.
 
Seems decision to cancel FARA was a close guarded secret or was taken very late in the process.

I had the Army brief me on FARA in December where they made no mention of this, even when I asked directly if this was a possibility. I’m disappointed in the decision to cancel FARA, but I’m also disappointed in the lack of transparency provided about this decision.
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Congressman Jackson disappointed by Army's 'lack of transparency'

abc7amarillo.com abc7amarillo.com
 
yasotay said:
I agree that it is unlikely that we are going to persuade anyone that their position is incorrect. I do know that the UCAR effort to design a purpose built uncrewed scout helicopter was cancelled because it would cost as much as, or more, than a manned platform and required a third more people to manage and operate.
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Well the crew isn't the biggest part of cost when you have scaled up so much, however there is almost no use case where you need all the capabilities that a dedicated helicopter provide at the same time. If not all capability is needed, another airframe can do the job while having a fraction of capabilities and thus costs.

The most questionability is helicopter's capability at hover, since if that requirement is out you can run STOL or VTOL with higher speed, range and payload. Hover near the front line or having penetrated enemy lines is very risky.

The other questionable item is the sheer scale of the vehicle. Modern sensors can have good performance while being cheap and light while scaling up doesn't necessarily improve things as line of sight is the hard constraint, and helicopters isn't very suitable for higher attitude recon spotting deep into opponent territory relative to a stealthy MALE drone.

"The DJI Mini 3 drone is engineered to withstand wind gusts up to 10.7 m/s, which equates to about 24 miles per hour,"(dronesurveyservices.com)...

The only wind limit for military helicopters (other than severe turbulence) is the not to exceed wind speed for starting the aircraft. This is usually between 30 and 45 knots, with larger rotorcraft able to withstand the higher wind speeds.
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A DJI is not designed for rough condition ruggedness or mobility. A racing quad can commonly hit 120mph and world record is over 170mph. Now you of course lose range and payload for this without scaling up the vehicle, but the form factor isn't the problem here.
Also for low cost vehicles, losses due to weather is also quite acceptable and margin of safety can be nothing. Frankly with 6G acceleration and instant pitch/roll on racing drones, wind, turbulence or fog doesn't seem like a big problem since you get get out of trouble so quickly.

If you take a look at off the shelf dji at 50kph winds, after all the digital gizmos cropping a horizon steady mode image you'd hardly feel the windspeed at all.
View: https://www.youtube.com/watch?v=Vh9IhB656cA

As for fog in general, small drones can simply get closer than just about all other recon vehicles, after all grenade dropping range is common and survivable.
View: https://www.youtube.com/watch?v=ZUMVSy-ls34



There is also many other aerial vehicles for recon, I suppose the thing to do is identify a specific use case first.
 
"There is also many other aerial vehicles for recon, I suppose the thing to do is identify a specific use case first."

This we can agree on.
 

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