Bell V-280 Valor

[lantinian]

I have watched the “hooah” promotional several times now and Bell crammed as much into that as they could for the discerning viewer. ..... if you watch in the background a couple of V-280 are sling loading a couple of M777 howitzers (UH-60 can’t do that),

Smart Observation.

Wikipedia lists M777A2 weight as 9,800 lb, while an UH-60 LIMITS - Army Aviation doc I found stated the following:

5.17 Cargo Hook Weight Limitation
For UH-60A aircraft, the maximum weight that may be suspended from the cargo hook is limited to 8,000 pounds. For UH-60L aircraft, the maximum weight that can be suspended from the cargo hook is 9,000 pounds.

This implies the V-280 load carrying capacity as at least 10,000 lb

 

[jsport]

I have watched the “hooah” promotional several times now and Bell crammed as much into that as they could for the discerning viewer. ..... if you watch in the background a couple of V-280 are sling loading a couple of M777 howitzers (UH-60 can’t do that),

Smart Observation.

Wikipedia lists M777A2 weight as 9,800 lb, while an UH-60 LIMITS - Army Aviation doc I found stated the following:

5.17 Cargo Hook Weight Limitation
For UH-60A aircraft, the maximum weight that may be suspended from the cargo hook is limited to 8,000 pounds. For UH-60L aircraft, the maximum weight that can be suspended from the cargo hook is 9,000 pounds.

This implies the V-280 load carrying capacity as at least 10,000 lb

from Global Security Website
"..FUR is not necessarily based on the UH-60 airframe but lists as goals, 175 knots cruise, 500 nm radius, 10,000lb external lift, 20% increase over UH-60L,.."

 

[VTOLicious]

Current plans call for two JMR technology demonstrator aircraft to be designed and built for a first flight by sometime in 2017, said Todd Turner, director for the Army’s Research and Technology Air Portfolio.
“This is an S&T [Science and Technology] effort for the development of a new, medium-class platform. The goals are to design, fabricate and demonstrate an advanced vertical lift vehicle with a combat radius of 424 kilometers, that’s an 848 kilometer range, un-refueled, at speeds of up to 230 knots,” Turner said at the National Defense Industrial Association’s 14th Annual Science & Engineering Technology Conference/Defense Tech Exposition, National Harbor, Md.
A key goal for the program is to be affordable, and develop an aircraft that can reach much greater speeds and extend mission possibilities without compromising an ability to hover, Turner said.

Some thoughts regarding hover efficiency and dimensions of the V-280:

The UH-60L has a rotor diameter of 16,36m, a disc area of 210m² and disc loading of 47,5/m² (@9980kg grossweight).

Despite the Osprey is a completely diffrent weight class, it has the same disc area (211m²). The rotors of the MV-22B are 11,6m in diameter.

For good hover efficiency we can assume the V-280 must have a similar rotor diameter to achive the Blackhawks (low) discloading. That would imply a wingspan of ~14m and width of ~26m with turning rotors! (same as the Osprey)

...yes, the V-280 doesn´t need to transfer power to a tailrotor or other anti torque device, but the downwash on the wings is a design penalty of tiltrotor aircraft and reduces powered lift.

Just as a side note, the Osprey has a disc loading of 102kg/m²

Regards, Michael

 

[F-14D]

Current plans call for two JMR technology demonstrator aircraft to be designed and built for a first flight by sometime in 2017, said Todd Turner, director for the Army’s Research and Technology Air Portfolio.
“This is an S&T [Science and Technology] effort for the development of a new, medium-class platform. The goals are to design, fabricate and demonstrate an advanced vertical lift vehicle with a combat radius of 424 kilometers, that’s an 848 kilometer range, un-refueled, at speeds of up to 230 knots,” Turner said at the National Defense Industrial Association’s 14th Annual Science & Engineering Technology Conference/Defense Tech Exposition, National Harbor, Md.
A key goal for the program is to be affordable, and develop an aircraft that can reach much greater speeds and extend mission possibilities without compromising an ability to hover, Turner said.

Some thoughts regarding hover efficiency and dimensions of the V-280:

The UH-60L has a rotor diameter of 16,36m, a disc area of 210m² and disc loading of 47,5/m² (@9980kg grossweight).

Despite the Osprey is a completely diffrent weight class, it has the same disc area (211m²). The rotors of the MV-22B are 11,6m in diameter.

For good hover efficiency we can assume the V-280 must have a similar rotor diameter to achive the Blackhawks (low) discloading. That would imply a wingspan of ~14m and width of ~26m with turning rotors! (same as the Osprey)

...yes, the V-280 doesn´t need to transfer power to a tailrotor or other anti torque device, but the downwash on the wings is a design penalty of tiltrotor aircraft and reduces powered lift.

Just as a side note, the Osprey has a disc loading of 102kg/m²

Regards, Michael

Couple of things to keep in mind. The Osprey's proprotors are smaller than optimum for its weight class because of the constraint of required clearance between the spinning disk and the island amidships. A lighter Tilt-Rotor with the same disk area would be expected to have greater efficiency and smaller downwash. As you state the requirement is "withou compromising an ability to hover". It does not say that you have to hover as efficiently as a Black Hawk, just tthat you have to be able to hover [as well as necessary to met the mission requirements].

Downwash over the wing is an unavoidable penalty for Tilt-Rotor, as is the weight of the wing. This becomes proportionally larger the smaller the aircraft. As with everything, you have to make tradeoffs, Is that hovering penalty worth it in order to get the greater speed, range with given fuel, etc. , you get with Tilt-Rotor? Looking at the reverse, is the hovering efficiency of a pure helicopter worth the lower speed, range, etc.? One thing that has to be considered in answering those questions is, how much of your mission is going to be spent hovering or at very low speeds?

As a side note, Tilt-Rotor gets some, though not all, of that loss back because it can have more "twist" on its blades. This is because you don't have to worry about pushing those blades through the air sideways at higher speeds.

 

[VTOLicious]

Couple of things to keep in mind. The Osprey's proprotors are smaller than optimum for its weight class because of the constraint of required clearance between the spinning disk and the island amidships. A lighter Tilt-Rotor with the same disk area would be expected to have greater efficiency and smaller downwash. As you state the requirement is "withou compromising an ability to hover". It does not say that you have to hover as efficiently as a Black Hawk, just tthat you have to be able to hover [as well as necessary to met the mission requirements].

Quote from a recent National Defense article:
http://www.nationaldefensemagazine.org/archive/2013/April/Pages/FutureVerticalLiftTakesStepForward.aspx

Data from the technical demonstrations will eventually inform the formal requirements for future vertical lift, but the Army has floated some of its desired capabilities. According to Mangum, the medium-lift variant would cruise at 230 knots, travel distances of about 263 miles and transport up to 12 combat-loaded troops. With such speed, range and payload, the Army could use the platform to “potentially self deploy [and] not be reliant on the Air Force or the Navy to get some place.” It also should be able to fly 6,000 feet on a 95-degree Fahrenheit day. Most existing helicopters can only fly 4,000 feet in those temperatures, which restricts operations during the hottest days in critical environments such as the Middle East and North Africa, Mangum said. The medium-lift aircraft, which is first in line to be developed, will take the place of the AH-64 Apache and UH-60 Black Hawk. Army officials have said building the medium-lift first will allow it to replace 80 percent of its rotorcraft. This variant will be much heavier at about 30,000 pounds than a Black Hawk at 22,000 pounds. “If you talk about a medium aircraft today, you’re talking about a Black Hawk, an Apache, a Huey. … Those, by weight category, would actually almost be light aircraft in the next generation of aircraft by the Army,” said a senior industry official who asked not to be named. “You’re really starting to stretch the capabilities of what we’re currently doing today and what we’re capable of doing tomorrow,” the official said. “So if there’s anybody who walks in who says the JMR design points are so easy that we’ve already got that developed, I’m proud of them because ... from my personal knowledge of all of these different companies and things that they’re doing, we’re all going to stretch to meet those goals.”

...Interesting

 

[jsport]

If there was a need for 10k lb payload under FUR there likely remains a reason for that capability. How big does a tiltrotor need to be for that lift? In an increasingly urban world (likely a largest mission set) what kind of down-wash are we talking for the that beast?

 

[yasotay]

How much time you spend in a hover is a real issue. One of the main reasons the Army got into VTOL aircraft was because they thought being tied to airports in the atomic age would not be productive. Of course the Marines showing them that taking hills from the top down was much better helped too. Looking at recent operations no one is hovering more than ten to fifteen percent of the time over land. This is almost the opposite of what a naval helicopter likely does in anti-submarine, plane watch and resupply. So finding a happy medium may be very difficult. I suspect the Navy/Marine requirement for helicopters to act like transformers will be a contentious issue as well. The new strategy that focuses the US on the Pacific (an operational theater that dwarfs all other theaters of operation) will have a huge impact on new combat systems. Now that I think about it that might be why the USArmy said tilt-rotors are operationally best.


On the down wash, I cannot see Bell telling a cash strapped customer they are going to give them something they really don't want. As mentioned above, the V-280 is smaller and less weight than a V-22 so I would imagine the out wash to be in the teens, vice the twenty-two fps of V-22. CH-47 and CH-53 are in the high teens and people work around them all the time.


As to 10K payload. Assuming the artillery remains a customer for Army Aviation and the artillery has a 9,500 lbs gun (they do), then a 10k hook seems in order.

 

[Tailspin Turtle]

Tailspin:

One thing I note from the video is that the proprotors on the V-280 seem to pivot a lot faster than they do on the V-22 or XV-15. I wonder if that's a function of not having to tilt the entire engine assembly. So even though fixed engines may be somewhat more complex, this might be another advantage. It minimizes the time that you're in that intermediate stage where the functions of the cockpit controls get "mixed". Also, since autorotation was discussed, I wonder if another consideration was that you could glide much farther to a landing area in fixed wing mode, but once there, with a more rapid translation of the proprotors, rotating them for vertical mode on final could make for a softer autorotational touchdown.

Pros and a con for non-tilting engines that I didn't think of when I wrote that are the better field of fire for a door gunner in helicopter mode, the lack of engine exhaust impinging on the deck/ground, and the loss of a counterweight for the transmission/rotor which require a more powerful actuator to go back to helicopter mode. I don't know if the speed of conversion in the V-280 video is correct; you would probably not be surprised to learn that marketers and art directors sometimes favor appearance over accuracy.

The problem in the intermediate phase is not that the cockpit controls get mixed (the response to the cyclic stick and pedals doesn't change and you usually set the Blottle at some power level and don't need to move it), but the fact that the proprotor is not being turned by the relative wind, neither windmilling like a propeller or autorotating like a rotor. As a result, the rotor rpm is slowing and low rotor rpm is both a bad thing and a hard thing to recover from without lots of altitude.

I also forgot to mention in addition to the degree of difficulty of a power-off reconversion, the "window" for a tiltrotor autorotation flare that results in a touchdown at an acceptable sink-rate is small relative to a helicopter's. In the XV-15 simulator, the Bell pilots could experience a double-engine failure in airplane mode at 270 knots or so at 100 feet above the ground; pull up, convert to helicopter mode, and establish autorotation; and accomplish a power-off rolling touchdown at a reasonable sink rate. (Of course, they didn't have much latitude as to where they were going to touchdown in that case.) As far as I know, however, in flight test they never went beyond the power-off conversion from airplane mode to helicopter mode and separately, low-power flares to a rolling landing. And that's the relatively low disk-loading, more agile XV-15. In my opinion, the Navy's decision to have the V-22 pilots stay in whatever mode they were in or going to when things got quiet is the right one. The V-280 would probably be somewhere in between in terms of the likelihood of a successful reconversion to helicopter mode and an autorotation touchdown.

 

[yasotay]

I saw a presentation a few years ago at the American Helicopter Society where they showed the testing of the (then) BA-609 going from forward flight to autorotation. I remember from the video that the rotor rpm dipped significantly during the conversion (they did the test from a significant altitude and did a full power recovery). If memory serves, they used the 95 degree nacelle angle to accelerate the build up of rpm. The decent rate was similar to an H-60 once they transitioned from airplane to rotor mode.


Certainly weight and prop-rotor design are going to have a lot of impact on the engine out characteristics of the V-280. I wonder if there is an optimum prop-rotor vector change rate, or if that is something best left to the aircrew to decide within the mechanical limits of the design?

 

[yasotay]

If there was a need for 10k lb payload under FUR there likely remains a reason for that capability. How big does a tiltrotor need to be for that lift? In an increasingly urban world (likely a largest mission set) what kind of down-wash are we talking for the that beast?

If the rotor diameter is about the same as a UH-60, it should work fine.

 

[jsport]

http://www.youtube.com/watch?v=Q-MP2tKhmQo

http://www.youtube.com/watch?v=PI9gWlM0QY8&feature=endscreen&NR=1

http://www.youtube.com/watch?v=SXeIjMJe_

 

[yasotay]

Yes ... and?
I have to assume from the videos that you believe that tilt-rotors will ALL be worse that helicopters in urban terrain. I will have to find the video of an MH-6 conducting an urban raid in Iraq. It blew materials up off the roof into its rotor system and crashed into the building.
Indeed I have to wonder if the thick cord of the prop-rotor might make it more resistant to damage than the thiner cord of most helicopters.

 

[jsport]

an operator told me a 25lb weight must be added to the fast rope so it is controllable upon decent...done with this topic.

 

[F-14D]

Tailspin:

One thing I note from the video is that the proprotors on the V-280 seem to pivot a lot faster than they do on the V-22 or XV-15. I wonder if that's a function of not having to tilt the entire engine assembly. So even though fixed engines may be somewhat more complex, this might be another advantage. It minimizes the time that you're in that intermediate stage where the functions of the cockpit controls get "mixed". Also, since autorotation was discussed, I wonder if another consideration was that you could glide much farther to a landing area in fixed wing mode, but once there, with a more rapid translation of the proprotors, rotating them for vertical mode on final could make for a softer autorotational touchdown.

Pros and a con for non-tilting engines that I didn't think of when I wrote that are the better field of fire for a door gunner in helicopter mode, the lack of engine exhaust impinging on the deck/ground, and the loss of a counterweight for the transmission/rotor which require a more powerful actuator to go back to helicopter mode. I don't know if the speed of conversion in the V-280 video is correct; you would probably not be surprised to learn that marketers and art directors sometimes favor appearance over accuracy.

Wel, Iwas comparing the posibly exaggerated rate of translation in this video with what I remember of the exaggerated rate in the early JVX/V-22 videos.

 

[flateric]

https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US8251305.pdf

 

[Triton]

Interesting that the patent shows a civil configuration.

 

[flateric]

more interesting that it shows attack version)

 

[lantinian]

Great find flateric .


I wonder if Bell is not considering this intermediate solution between a conventional helicopter and a tilt rotor as an better answer to the FTL. The tilt rotor with its 280 knots speed is an a requirement overkill but also too mechanically complex. Perhaps this configuration can achieve the required 230 knots with this variable incidence wing approach in a lot more simple and reliable design.

 

[F-14D]

Great find flateric .


I wonder if Bell is not considering this intermediate solution between a conventional helicopter and a tilt rotor as an better answer to the FTL. The tilt rotor with its 280 knots speed is an a requirement overkill but also too mechanically complex. Perhaps this configuration can achieve the required 230 knots with this variable incidence wing approach in a lot more simple and reliable design.

Ditto the find!

Can't say if the variable incidence wing is that much less complex, but Bell states that their 280 knot speed is a fallout of the 6,000 ft., 95° F requirement. With the power required to do that, when you rotate the proprotors forward, you get a 280 knot cruise

 

[lantinian]

Can't say if the variable incidence wing is that much less complex,

It's it obvious? You don't have a transfer of torque trough the mechanism.

Bell states that their 280 knot speed is a fallout of the 6,000 ft., 95° F requirement. With the power required to do that, when you rotate the proprotors forward, you get a 280 knot cruise

Interesting. ??? So the question is then how much tilt of the propellers is required to achieve 230 knots?

 

[F-14D]

Can't say if the variable incidence wing is that much less complex,

It's it obvious? You don't have a transfer of torque trough the mechanism.

Bell states that their 280 knot speed is a fallout of the 6,000 ft., 95° F requirement. With the power required to do that, when you rotate the proprotors forward, you get a 280 knot cruise

Interesting. ??? So the question is then how much tilt of the propellers is required to achieve 230 knots?


Granted, you do not have a transfer of torque through the mechanism. That would qualify as reduced complexity, sure. Of course, you could also do that by just tilting the engines, as the last three Tilt-Rotor aircraft did.

If I understand the concept, not necessarily a given ("Mongo just Pawn in Game of Life"), the rotors are fixed at an angle relative to the engines, which are fixed on the wings and the wing itself has a degree of variable incidence. While this would not require the transfer gearcase of the V-280 style Tilt-Rotor, it introduces some complications of its own. Of course, one is you're now moving the entire wing. A second is that in forward flight you've now got the rotors in an inefficient configuration. They're not in the most efficient lifting position for a rotorcraft, nor are they in the best position for propulsion. Sort of a "least of both worlds". The thrust vector is not aligned with the direction of flight, requiring some complexity there. Also, the rotor-wing downwash penalty, which Tilt-Rotors face when in vertical mode but disappears in aircraft mode, is there all the time. There are some design and control issues there. What you are creating here is a Tilt-Rotor with the proprotors always in intermediate position. Generally a Tilt-Rotor will only have the proprotors at this angle during STOL operations, and will rotate them fully as soon as practical, while here you're flying in intermediate mode all the time. Finally, because of the angle depicted relative to line of flight, you reintroduce the complication that at speed you're essentially pushing the rotors though the air sideways. This means you can't use the maximum twist to the blades. You've also got more drag to deal with.

I would opine that there are some advantages relative to conventional helicopters. In fact, Fig. 9 resembles a conventional helicopter in higher speed flight. It allows for a more level cabin than a helicopter in most modes. This might be an interesting alternative to X3. However, I don't see significant advantages relative to Tilt-Rotor (or ABC/X2, once there is more experience with it).

In answer to your 2nd question, I must ask another: If you're already got the power and are tilting anyway, why would you want to stop at an intermediate, less efficient angle just you can go slower?

 

[lantinian]

If you're already got the power and are tilting anyway, why would you want to stop at an intermediate, less efficient angle just you can go slower?

Simple. You trade speed and range for reliability and survivability.


I agree with most of your arguments but I think you missed the general point I was making, so lets try again.
Any Tilt-Rotor has proven to bring the following 3 advantages compared to a conventional helicopter
- speed
- payload
- range
Looking at the JMR/FTL requirement V-280 meets or exceeds the payload requirements and vastly exceed those in speed and range.


However, the V-22 has proven that a tilt-rotor is also a lot more complex than a conventional helicopter to a point where that complexity may seriously affect the ability of the aircraft to perform its mission safely. The fact the US President will never get one despite the advantages it brings proves that.


My point was that the above patent represented an attempt by Bell to trade speed and range (which they had plenty of above the requirement) for reliability and survivability.


Now, why do I think that they get what they want?
In a V-280 you have 3 moving things to worry about breaking (sorry if I use incorrect terminology)

• 2 propellers
• 2 propeller pivoting mechanisms
• 2 mechanisms for transferring torque at different pivoting angles

Further, you have all those 6 moving systems grouped in 2 small areas. You can say thay you are putting all of your eggs in 2 baskets.


In the patent above Bells engineers sacrifice the forward flight configuration of tilt rotor but achieve the Vertical and STOL oneswith just the following moving systems:

• 2 propellers
• 1 mechanism for pivoting the whole wing.

Now, not only you reduce these complex moving mechanisms in half but you distribute them in the whole aircraft reducing the risk that a single hit will damage more than 1 of them.


Granted, this is oversimplification but there is a general logic there. Now, if you look at a conventional helicopter the same way it has only 2 propellers and no big pivoting parts. An X2 or a compound helicopter have both 3 propellers and no moving parts so one can make the crude arguments that the patent above gets the best of the tilt rotor for half the complexity.

Also, the rotor-wing downwash penalty, which Tilt-Rotors face when in vertical mode but disappears in aircraft mode, is there all the time.

You are comparing apples and oranges here.In a vertical flight the above patent will face less downwash then a tilt-rotor because the wing is at an high alpha (less air is trapped). In STOVL flight both will behave exactly the same as they have the wing and rotors exactly the same way. The tilt wing concept does not have the efficient aircraft mode at all but that's the whole point. It may achieve the range and speed requirements without it.My whole argument is that the ability to point the main propellers fully forward drives the decision to incorporate the pivoting mechanism from one area in the strongest structural section ( the aircraft central fuselage) to the weakest places, the 2 tips of the wings.

 

[F-14D]

lantinian,

Very interesting and thoughtful perspective. Thanks for taking the time. My thoughts, FWIW:

As far as vastly exceeding speed and range, that's true. However, clearly Army wanted to look at a variety of technologies, a good plan. if they set those requirements much higher, they would have effectively pre-selected Tilt-Rotor. Again, what Bell is doing is leveraging the power they're going to have to have to meet the 6K 95F requirement anyway and harnessing it fully.

Regarding the V-22's problems, AFAIK they haven't been related to how it tilts its proprotors, or even to the fact that it's a Tilt-Rotor. Regarding Presidential use, I'm not sure how you can state the US President will never get one since there are already 12 being delivered to HMX-1 for support roles and to fly the press and other personnel. As far as Marine 1 goes, the V-22 is considerably larger than the existing assets (note pic), so that's a consideration--do we need one that large? Plus, they love to have their competitions, you know, so they're going to have another one for that. On the other hand, maybe with something this big, they can carry all the stuff the Secret Service keeps wanting to pile in there, which is what killed the VH-71. Depending on what they want the new one to do, the V-22 may indeed get bid. Boeing is also considering separately bidding the CH-47. In any case, President Obama doesn't seem to be too worried, as he tends to use the V-22 abroad when its available, something neither he nor the Secret Service would tend to put up with if the complexity seriously affected its ability to perform its mission.

There's actually a complexity you left out regarding the concept under discussion. Specifically, since its propellors are not in line with the with the engines (as they could be on an engine tilting Tilt-Rotor but not on a fixed nacelle one), you've got to have some kind of power transfer case in there. Granted, it won't have to move, but it's a complicated gearcase nonetheless. Plus, you have the thrust vector not in line with the motion of the a/c, which has to add stress to that gearcase and mount (Tilt-Rotor has it too, but normally only for a small portion of the flight, and only at lower speeds).

Not sure how this concept would be more survivable. A 57mm hot in the nacelle of a Tilt-Rotor or this is pretty much going to take out everything, and with this concept you have the additional vulnerable area where the wing tilting mechanism is. In both cases, BTW, the heavy engines are sitting out on the wing tips. OTOH, both concepts can land safely with the props forward, but this one can do it more nicely.

On a conventional helo, you have a lot of moving parts in the rotor hub, and it gets really complex in there. Possibly even more so for X2, but not to a dangerous or unacceptable level. Of course,with X2, should that rear prop or related shaft be knocked out, it looks like it'll be slower than a conventional (a conventional helo in this situation immediately become a thrill ride).

I don't think I'm using different fruits here. It seems the the rotor-wing interaction is going to be a function how much the blades overlap the wing in Tilt-Rotor or VI wing some will get deflected aft and down because the wing has some tilt on it in the hover, but it still going to have the downforce impinging on it as a function of wing area and overlap. It will be reduced in forward flight because of the effect that forward motion will have on the displaced air, but it'll still be impinging on the wing.

I guess all I'm saying is that it seems that what you have to give up with the VI wing concept seems an awfully high price to reduce what doesn't seem to be to be that much of a problem.

Again, FWIW

 

[TaiidanTomcat]

I'm not sure how you can state the US President will never get one since there are already 12 being delivered to HMX-1 for support roles and to fly the press and other personnel. As far as Marine 1 goes, the V-22 is considerably larger than the existing assets (note pic), so that's a consideration--do we need one that large? Plus, they love to have their competitions, you know, so they're going to have another one for that. On the other hand, maybe with something this big, they can carry all the stuff the Secret Service keeps wanting to pile in there, which is what killed the VH-71. Depending on what they want the new one to do, the V-22 may indeed get bid. Boeing is also considering separately bidding the CH-47. In any case, President Obama doesn't seem to be too worried, as he tends to use the V-22 abroad when its available, something neither he nor the Secret Service would tend to put up with if the complexity seriously affected its ability to perform its mission.

I agree with all of the above. Personally I would absolutely love for Marine One to be an Osprey. Something wonderfully advanced and science fiction like for pres to have a "tranformer" helicopter. the V-22 is a sporty car, the Chinook is a truck. I don't think there is any way to make a chinook look like anything other than a big tandem rotor brick. Looks wise, the osprey wins, A lot of the critisms like downwash could be applied to the Chinook as well. Its probably a big advantage that HMX will have experience with the osprey, along with being able to get good maintainers with osprey experience from the fleet, as opposed to having to reinvent the wheel with the Hook. I think a lot of the minuses for the osprey will go out the window since there are already 12 in service.

 

[F-14D]

I'm not sure how you can state the US President will never get one since there are already 12 being delivered to HMX-1 for support roles and to fly the press and other personnel. As far as Marine 1 goes, the V-22 is considerably larger than the existing assets (note pic), so that's a consideration--do we need one that large? Plus, they love to have their competitions, you know, so they're going to have another one for that. On the other hand, maybe with something this big, they can carry all the stuff the Secret Service keeps wanting to pile in there, which is what killed the VH-71. Depending on what they want the new one to do, the V-22 may indeed get bid. Boeing is also considering separately bidding the CH-47. In any case, President Obama doesn't seem to be too worried, as he tends to use the V-22 abroad when its available, something neither he nor the Secret Service would tend to put up with if the complexity seriously affected its ability to perform its mission.

I agree with all of the above. Personally I would absolutely love for Marine One to be an Osprey. Something wonderfully advanced and science fiction like for pres to have a "tranformer" helicopter. the V-22 is a sporty car, the Chinook is a truck. I don't think there is any way to make a chinook look like anything other than a big tandem rotor brick. Looks wise, the osprey wins, A lot of the critisms like downwash could be applied to the Chinook as well. Its probably a big advantage that HMX will have experience with the osprey, along with being able to get good maintainers with osprey experience from the fleet, as opposed to having to reinvent the wheel with the Hook. I think a lot of the minuses for the osprey will go out the window since there are already 12 in service.

In the interest of full disclosure, only one of the 12 has been deliverd to HMX-1. However, about 230 V-22s in total have been deliverd to USMC and USAF so far.

 

[TaiidanTomcat]

In the interest of full disclosure, only one of the 12 has been deliverd to HMX-1. However, about 230 V-22s in total have been deliverd to USMC and USAF so far.

you are indeed correct, got a little ahead of the timeline in my post

 

[VTOLicious]

An Article regarding the "Hybrid Tandem Rotor" from The DEW Line (2009):

http://www.flightglobal.com/blogs/the-dewline/2009/05/bell-helicopter-reveals-hybrid.html

...It is Bell's candidate for replacing both the AH-64 and UH-60 with an all-new configuration called the Hybrid Tandem Rotor, Robert Kenney, Bell's executive VP for government programs, told me in an interview a few minutes after I filmed this clip.

The HTR "splits the difference between a helicopter and a tiltrotor," said Kenney.

While the BellBoeing V-22 can tilt its tandem rotor 95 degrees, the HTR's wing tilts by 25 degrees and gains 5 degrees more by adjusting the cyclic controls.
That means the HTR could achieve a forward speed of 225kts, Kenney said. A V-22 cruises at more than 300kts, while the fastest helicopters are limited to about 170kts...

Rgds Michael

 

[lantinian]

Regarding Presidential use, I'm not sure how you can state the US President will never get one since there are already 12 being delivered to HMX-1 for support roles and to fly the press and other personnel.

Saying never was a bit harsh on the V-22, I admit. I was simply referring to this piece which I remember reading last week
http://www.defense-aerospace.com/articles-view/feature/5/144961/v_22-%E2%80%98reputation-remake%E2%80%99-falls-flat.html

Ulsh noted that last month the first of 12 Ospreys joined the fleet of aircraft used for presidential travel, a significant endorsement of the aircraft. They’ll be used to transport the president’s staff and journalists, though not the commander in chief.

The program to find a replacement for the Presidents current helicopter has recently been restarted with the V-22 being possibly one of the candidates.
http://news.yahoo.com/u-navy-moves-ahead-presidential-helicopter-program-183652898.html

Boeing Co has said it is also studying a possible bid based on its H-47 Chinook helicopter or the V-22 Osprey tilt-rotor aircraft that it builds with Textron Inc's Bell Helicopter unit.

So, officially the V-22 is still far from being Marine Force one. Don't get me wrong thought. I'd love for the V-22 to take that roll but the reality is that they may need a solution with a much more benign footprint. Imagine how much reporters are going to love it when they learn that because of the huge V-22 downwash, they now have to wait 3 times further from the landing zone to take pictures.

There's actually a complexity you left out regarding the concept under discussion. Specifically, since its propellors are not in line with the with the engines (as they could be on an engine tilting Tilt-Rotor but not on a fixed nacelle one)

You are right. An that would have been the case had I compared the "hybrid tandem rotor" (as illustrated bellow) with V-22. However, Bell's JMR/FTL proposal is different than V-22. I was specifically referring to the V-280 the whole time which also has fixed engines.
So again in terms of the way the engines and the propellers connect:

• V-22 (Apples),
• V-280 (Oranges),
• "Hybrid Tandem Wing" (Oranges),
• "Variable Incident Wing" (Oranges)

I don't think I'm using different fruits here. It seems the the rotor-wing interaction is going to be a function how much the blades overlap the wing in Tilt-Rotor or VI wing some will get deflected aft and down because the wing has some tilt on it in the hover, but it still going to have the downforce impinging on it as a function of wing area and overlap. It will be reduced in forward flight because of the effect that forward motion will have on the displaced air, but it'll still be impinging on the wing.

This is all 100% correct. What I meant is that you should not compare the aircraft configuration of a Tilt Rotor with the STOVL configuration of a VI wing which to me is comparing apples and oranges.


Also, the program is called Future Vertical Lift for a reason. It's Future "best possible vertical" lift, not Future "needs to fly like an airplane but hey, by the way, can you make it land like a helicopter" lift. So IMHO, the advantage a VI wing has in less wing downwash (because of the tilt) is much more important than the airplane mode of the Tilt-Rotor.

A 57mm hot in the nacelle of a Tilt-Rotor or this is pretty much going to take out everything, and with this concept you have the additional vulnerable area where the wing tilting mechanism is.

Sorry but there is a complete lack of logic here.

1st, there is no requirement to for any helicopter to withstand a 57mm round, or a missile or a tank shell, or a 2000lb laser guided bomb of the kind an F-15E dropped on a Iraqi chopper in 1991. A hit by 23mm shell is
the most likely scenario to test against.


2nd, I am not adding anything. Bell is replacing 2 rotating nacelle titling mechanisms with 1 pneumatic one that will be far more reliable because its a more efficient way to achieve the same effect.

Take a home broom and ask yourself this. Which the most efficient way to tilt the broom from horizontal to 25 angle?
a) (V-22) grab the broom around the middle and twist your arm?
b) (V-280) grab the broom by the furthest corner of the stick and twist your arm? Ouch
c) (VI wing) put the handling stick against the wall and just lift the broom part up or down.
I am pretty sure, unless you are really strong, you won't be able to do option b)

So the wing tilting mechanism is by the laws of physics is a much more efficient, simpler and hence reliable and battle resistant solution to tilting the propellers from Vertical to STOVL mode.


3rd, spreading critical systems around the aircraft is a basic survivability concept. Its self evident.

On a conventional helo, you have a lot of moving parts in the rotor hub, and it gets really complex in there. Possibly even more so for X2, but not to a dangerous or unacceptable level.

Yes, you are right here. All till-rotor / VI wing solutions do seam to have an aircraft like propellers which have twisted blades attached to the center rotating shaft while conventional helicopters have blades which are mounted via joints as they need to be able to chance angle of attack. X2 and AH-56 Cheyenne operate differently though.

 

[F-14D]

Don't want this to turn into a back and forth thing that could bore everyone, it's only my opinion anyway, so I'm just going to clarify my thinking on how I adressed three issues.

Regarding Marine 1, the V-22 unquestionably is going to have greater downwash than an SH-3/H-60. It's a lot bigger for one thing. How significant this will be depends on how the specs come out. After all, if an H-47 will be acceptable, than this may not be that important. And, how close do the reporters need (and will be allowed, these days) to get to be able to use the superb long lenses we have nowadays. Generally, I see them being held in a press area anyway, whenever the President goes anywhere, at least until engine shutdown. Maybe they'll have to duck back in the V-22 they arrived in to get a different lens. Again, V-22 is by no means a sure thing and I'm not implying it is.

Regarding comparing the STOVL config of VI wing vs. aircraft config. of Tilt-Rotor, as I see it, VI wing is always in STOVL config because of the fixed relationship of the props to the wing. There will be the same amount of overlap regardless of VI wing's angle and there will be a downward component applied to the wing at all times because the prop is "blowing" down on it (minus whatever part is deflected by the relative wind derived from forward flight). I feel the use of Tilt-Rotor in aircraft config is fair because that's the configuration it'll be in at cruise. So, to my mind comparing what happens in the cruise config of Tilt-Rotor with the cruise config of VI wing is valid.


Finally, I used the 57mm comment simply to illustrate that if you get hit in the nacelles with something large enough, the whole nacelle is going to get smashed regardless of whether or not something in there rotates. I don't see a significant difference in vulnerability of the nacelles in either case. Ya get hit there, it's gonna hurt. The V-22 meets the DoD requirements for vulnerability to 23mm API.

 

[elmayerle]

Looking back on the complicated development history of the operational Bell VTOL, it is good to see that the complicated solution of tilting two enormous engines+props has been discarded.

I'm not quite sure, that tilting the rotors only, with the need to bend the cyclic and collective controls
really eases the problems. To my opinion, it may result in a slight decrease in weight, but to an increase
of complexity.

Trust me, as someone currently working on the V-22 nacelle, it makes a difference. And, yes, I'm very familiar with that V-22 testbed that was pictured a few months back in Combat Aircraft; further deponent sayeth not.

 

[lantinian]

I feel the use of Tilt-Rotor in aircraft config is fair because that's the configuration it'll be in at cruise. So, to my mind comparing what happens in the cruise config of Tilt-Rotor with the cruise config of VI wing is valid.

Looking at it operationally is the valid point of view indeed. We just can't agree on which is more important for the FTL: Cruse or VTOL.


Had the FTL requirement been to design the fastest and furthest traveling VTOL aircraft the Tilt-Rotor would probably be the best possible technical solution by far. After all, it does look like and airplane more than a helicopter in flight.


However, that's not where the requirements are being challenged by the reality of combat.
The real challenge is in going up in those high mountains in Afganistan and operating with heavy payload at a very hot day.
In those conditions, less downwash from the wing and more efficient transfer of power are far more important.

I guess that the debate will be settled by what configuration Bell proposes to build at the end (if they win the final contract).

The things is, we do have members in this tread (who had not posted for 2 years) but who probably knows ....something.

 

[yasotay]

A great discussion going here, having been away for a bit, I will do my best not to prognosticate too much.

I was under the impression that Bell had already elected to move forward with tilt rotor. Mr. Garrison seemed pretty straight forward at the Quad A meeting that V-280 would be the Bell FVL option. Of course that could change, but I am a great doubter of industrial agility, especially in the American rotorcraft sector.

I suspect that the hybrid tandem rotor was a "floater" that Bell put out to see if a very conservative Army would nibble at. Since it appears that the Army has not "nibbled" I suspect the concept (still very valid) goes into the overstuffed vault at Bell.

I must disagree somewhat with the "challenged by the reality of combat" comment. To be sure the horrible environment US/NATO rotorcraft have been operating in the last ten years has demonstrated the need for more power/payload. So a desire for the ability to operate at 6000 feet on a 95 degree day that has been put forward seems valid. Good news with this is that anywhere cooler and lower (much of the earth...well maybe) will allow for even better performance than that at 6000 feet.

Nonetheless, range and speed have also become very salient points. Otherwise I seriously doubt the Army would not have doubled the desire for both of them. The distances that the US forces have been operating over are far greater than the current fleet is designed for. This has required them to either penny packet helicopters (in the case of MEDEVAC) or put Forward Area Rearm/Refuel Points (a.k.a. gas stations) all over the map. For senior commanders this creates undesirable circumstances. First they have to protect all of those expensive helicopters/crews/maintainers and their gas stations. This means more people at risk than would otherwise be in harms way. Along with this they have to get fuel/parts/supplies out to those locations and that means convoys, because it is not practical to move bulk fuel by air. That puts even more soldiers at risk. At a meeting in January of this year the Army Aviation Commander showed a slide comparing coverage requirements for the Philippine between current and future rotorcraft. It showed that today it would take nine operating bases to cover much of that country. With the future requirements it would take only four. That is a lot less people. So being able to operate at long distances can lead to a more streamlined force. He also showed future rotorcraft self deploying across the Pacific ocean in something like four days. Given the US decision to focus more effort on the Pacific Region (it dwarfs any other area I suspect), “range” will be very important I suspect.

Speed will likely be the contentious point. How fast is fast enough? The Aviation Commander said that 230 knots was the current desired cruise speed. I personally am in favor of speed because of the old military aviation maxim "speed is life", and how it relates to soldiers on the ground. If you had a choice of being shot at for five minutes or ten minutes before someone comes along to help you, which would you choose? If you had a choice of your child bleeding out for thirty minutes or fifteen, which would you choose? Less emotionally if "time is money" then the more time it takes to accomplish a mission means more wear and tear on an aircraft. Certainly there is a valid argument about cost of a system per flight hour that can stand the comment on its head, but one has to consider whole ownership cost over a long period to have a better picture. Connected to this is fuel efficiency. The operating cost of an aircraft will see fuel cost become a more critical component as more people bid on the available fuels. Most westerners are used to relatively cheap fuels (especially the US), so it has not really been a part of the “expense” consideration. I think this attitude will change fairly soon. So rotorcraft efficiency will become a more critical component of effectiveness.

This is why I think tilt rotor has a good chance, which appears to be consistent with an Army study that Bell likes to quote.

 

[lantinian]

It would be interesting to note that we still have not seen Boeing's X2 based proposal.

Sikorsky will continue developing the S-97 on its own and Boeing has taken responsibility for the team JMR entry. Since decision on which 2 teams will proceed with the prototypes is due in September, we are bound to see something interesting from Boeing in the next 1-2 months.

I've been gathering the specs of the more notable contenders and the latest versions of the helicopters they are poposed to replace.

It's quite obvious that in terms of payload, S-97 is not in the same leagues as the others and that V-280 is also in a leagues of its own.

There are a few empty fields if anyone wants to help, you can do so here:
https://docs.google.com/spreadsheet/ccc?key=0An6LyF8qNyoudC1DV0tRUEhfc2RGQnBOVC1IdlgwV3c&usp=sharing

 

[yasotay]

The Boeing/Sikorsky team has Sikorsky developing the X2 air vehicle and Boeing responsible for the mission equipment. So unless I have missed the mark, there will be no Boeing air vehicle.

 

[F-14D]

It would be interesting to note that we still have not seen Boeing's X2 based proposal.

Sikorsky will continue developing the S-97 on its own and Boeing has taken responsibility for the team JMR entry. Since decision on which 2 teams will proceed with the prototypes is due in September, we are bound to see something interesting from Boeing in the next 1-2 months.

I've been gathering the specs of the more notable contenders and the latest versions of the helicopters they are poposed to replace.

It's quite obvious that in terms of payload, S-97 is not in the same leagues as the others and that V-280 is also in a leagues of its own.

There are a few empty fields if anyone wants to help, you can do so here:
https://docs.google.com/spreadsheet/ccc?key=0An6LyF8qNyoudC1DV0tRUEhfc2RGQnBOVC1IdlgwV3c&usp=sharing

In fairness to Sikorsky, S-97 is not meant to be able to compete for this program, it's too small. It's more in the size of the Advanced Aerial Scout Program (AAS). Origninally it was looked at as a long shot because Army was investigating off the shelf stuff for AAS and said it would only consider stuff that was flying now. However, based on the results of the 2012 "flyoff", Army has decided that no off-the-shelf solution can met their needs for a new vehicle. So, they either stay with the OH-58 or develop something more advanced, and there S-97 has a shot.

V-280 is probably too big for what Army wants for AAS.

Or, Army could wait for the "scalable" FVL results (SLEP OH-58 for another decade or so) and adapt something from that.

 

[Avimimus]

Well Sikorsky has been showing around a bunch of different X-2 concepts and patents - including enlarged military versions.

I wouldn't be surprised if one of these gets submitted for the JMR role. The question is - have any estimated stats been published yet for the larger versions?

 

[F-14D]

Well Sikorsky has been showing around a bunch of different X-2 concepts and patents - including enlarged military versions.

I wouldn't be surprised if one of these gets submitted for the JMR role. The question is - have any estimated stats been published yet for the larger versions?

There is actually a differnt forum on the site for JMR. You can see a pic of the Sikorsky Boeing X2 concept here:
http://www.secretprojects.co.uk/forum/index.php/topic,13812.msg178946.html#msg178946

 

[Stargazer]

https://dl.dropboxusercontent.com/u/5302558/Photos%20for%20Links/JMR%20Comparison.png

Your Dropbox link not only doesn't show (I had to fetch it from your source post) but it doesn't work!

Can you provide an alternate URL that is accessible to all? Thanks.

 

[Avimimus]

Well Sikorsky has been showing around a bunch of different X-2 concepts and patents - including enlarged military versions.

I wouldn't be surprised if one of these gets submitted for the JMR role. The question is - have any estimated stats been published yet for the larger versions?

There is actually a differnt forum on the site for JMR. You can see a pic of the Sikorsky Boeing X2 concept here:
http://www.secretprojects.co.uk/forum/index.php/topic,13812.msg178946.html#msg178946

Ah, yes... I just was providing some feedback for lantinian's comparison sheet.

 

[lantinian]

https://dl.dropboxusercontent.com/u/5302558/JMR%20Contenders.png

Your Dropbox link not only doesn't show (I had to fetch it from your source post) but it doesn't work!

Can you provide an alternate URL that is accessible to all? Thanks.

I fixed the picture but it was just an image for illustration purposes. The link to edit the table was bellow it and it still works.
Here it is again.

https://docs.google.com/spreadsheet/ccc?key=0An6LyF8qNyoudC1DV0tRUEhfc2RGQnBOVC1IdlgwV3c&usp=sharing