New Bell product - Bell V280
 

Saw this on my Facebook account alert around half an hour ago that Bell was announcing something new within 10 mins or so at Quad A

BellV280.com

Cheers

http://www.bellhelicopter.com/Military/Military.html

Nothing at the bell home web site, might this be a "hey, why don't you guys write a requirements document for this because we want part of the UH-60M market" or something like that?

Then again, might be a "future capability" brief at AAAA.

Blackhawk meets AW609!

If such a vehicle were to be commissioned I have my doubts as to whether it could achieve an operating cost below say a stretched version of the Sikorsky Raider.

Tilt-rotors are, for the moment, notoriously expensive to both build and operate!

V280
 

Guaranteed to have compound walls programmed into the navigation database no doubt.

Just like this...:rolleyes:

I had read that James Cameron had bought shares in Textron, now we know why. :p

Oh how clever of you, but I think AW had the Avatar Scorpion copy-contest pretty well covered with Project Zero (unless you are merely comparing color):

http://theaviationist.com/wp-content...ect-Zero_1.jpg

Plus, it looks like Bell was astute enough to know not to keep ducts around the rotors for edgewise flight....something that it appears Agusta had to discover sometime over the course of their secret 2 years (based on the photos)

Excellent idea Rabina!

This is Bell's JMR/FVL medium concept. Sikorsky and Bell are the two most likely candidates for JMR flight demo contracts (a Sikorsky compound and a Bell tiltrotor). Sikorsky and Bell have the most experience with their respective configurations which gives them a big advantage over their JMR competition in terms of development risk.

While the Bell V-280 fuselage does bear some resemblance externally to the Blackhawk, there actually is a valid reason for Bell doing this. The FVL medium is intended to replace the US Army Blackhawks, and it's well known that the US Army is very conservative when it comes to adopting new aircraft. By giving their V-280 fuselage a similar appearance to the Blackhawk I think they are trying to create a sense of familiarity with the Army, and thus a reduced perception of development risk.

Another thing that shows Bell is serious about minimizing development risks, whether perceived or real, is the V-280's use of a non-tilting engine. While this approach makes the drivetrain design a bit more complex, it also means that they won't have the added cost and risk involved to develop and certify a new turboshaft engine model that can tilt.

I personally think the Army would be better off with a tiltrotor for FVL. While a compound would be a bit less risky, the tiltrotor has more potential for future improvements in terms of speed, payload, range, etc.

Should be an interesting competition with two hybrids in the running.
I bet no matter what they choose as a Blackhawk replacement it won't be on time or under budget!
Im assuming it will have to be air transportable like the '60s so will be very interested to see how they would stow the wings and tail for a C-17 trip.
Self protection will be a bit different too, no door gunners like the '60s. That's an absolute must-have but not shown in the photos.
Should be a great competition!

In all its subscale glory:

http://i.imgur.com/lVhyaZR.jpg

Going to be interesting to see whether FVL-M does end up with a Hawk-sized cabin, or whether a larger troop load-out is selected. Some of the preliminary studies point to something closer in weight to a Chinook. Let's see if it weathers mission creep better than JHL did.

I/C

V-22's today are self-deployable with air refueling... the same will go for this concept.

Riff Raff: I hear what you're saying and there's no denying that with those massive pylon-wings you should be able to lift some impressive loads - especially if they develop the rolling take-off technique.

But the 'planform' of this contraption is considerably larger (and therefore in my view more vulnerable) than the Raider concept. Plus, with the tilt-rotor you have two unique heat signatures effectively giving your assailant unnecessary opportunity.

I understand the advantages of swift troop insertion/extraction but .. at what cost? Financial analysts predict that US defence budgeting will come under increasing strain over the next two decades with the role of the Defence Secretary requiring skills more closely associated with that of alchemy than tactical politics and at the moment I simply can't see how titlt-rotor technology can be cost-effective. I may be wrong.

TukTuk: As Phlying has said, the larger troop-carrying versions are designed to be self-deployable .. if not through in-flight refueling then by leap-frogging (if the US has sufficient allies in the right places at the right time to accommodate their fuel stores).

Re: Door gunners .. surely these are a thing of the past .. except for movie-makers! This function can be far better served by a weapons officer or second pilot using fore and aft mounted turrets through electronic sights. If it doesn't already exist then I am sure it is only a matter of time until this function is completely automated with the role of the weapons officer/second pilot merely being that of confirming that the computer has identified a hostile as opposed to friendly target.

Based on what was published, there was a requirement for 24" per seat width and at least 66" cabin height. If nothing changed, it would mean more a S-92 size cabin.


Arrakis

Mmhh, Bell walked out of the 609...I wonder what the development costs and TIMES are going to be for this...

Plus they are likely to need a gross weight increase AFTER they give it to the ARMY.:rolleyes:

But I believe that in the end Bell shall try to sell the ARMY the umpteenth development of the 412.:E

I vote for the Raider.

Why do people keep talking about the Raider for FVL?

It's far below FVL medium size requirements. Sikorsky and Boeing have already shown their concept art.

To date, no ABC/X2 has been built with a GW greater than what 12,000lb, and about a 35' rotor diameter. Anyone care to guess why that might be?

And how is a compound less risky? There is zero precedent in service. You have a whole fleet of V22s with over 150k flight hours in operation. No ABC has ever been even remotely fielded. The highest time on any ABC prototype airframe was what? 100 hours?

As discussed ad nauseum in the X2 threads on here, while the whole aerodynamic concept of a high hinge offset ABC rigid rotor is scalable, the reality of blade construction and subsequent required rotor spacing means drag increases exponentially. Do we all forget how Sikorsky suddenly dropped their large scale 737-fuselaged concepts in late 2006? Why was XH59 abandoned in favor of tiltrotors in the late 70s early 80s for JVX?

Simply put, a large scale X2 concept is a dog and pony show. I would not be surprised if Sikorsky and Boeing go to FVL and demo with the S97, and then CLAIM that it can be scaled up to FVL medium requirements.

Both Boeing and Sikorsky want FVL dead. Their revenue streams exist with UH60 and AH64. Boeing teaming up with Sikorsky is a win-win for them. But they have to make a presence in the FVL competition either way. The cheapest option is to show the large scale concept art, demo the S97, make outlandish claims (i.e. $15 mil for S97), and try to get the program killed.


http://www.aviationweek.com/Portals/...20JMR%20X2.jpg

Plus who in the world would say this thing was "considerably smaller"? Sure, the S-97 is considerably smaller than the Bell....because it is being pitched for AAS against a Kiowa.

In my case I am talking about the economics of Raider vs Tilt-Rotor irrespective of FVL and in a compatible comparison (ie. between two aircraft of similar size and payload specification).

Well then you have no baseline with which to compare, which was partially my point. Saying that a given tiltrotor is expensive to build and operate is a statement relative to a simple helicopter, not to some wholly unbuilt and untested compound.

Where does one get the idea that a coaxial ABC is simpler or cheaper than anything? Theres a valid technical argument that you cannot even build a functional high speed ABC above a certain rotor diameter. So scaling up actually argues the opposite point.

(Plus, you don't honestly believe the Sikorsky line that an S-97 would cost $15 million do you? Maybe without mission systems or a rotor!)

Has Bell even mentioned the target cost of this aircraft yet?

Let me put it in even 'plainer' English; I already said that my remarks relate to a 'compatible comparison' irrespective of whether or not the Raider can achieve any specific size.

If for example the Raider's 'constructional limit' it a 10 place aircraft then what I am saying .. is that I believe it will be me more cost-effective to build and maintain the Raider concept than a Tilt-Rotor of comparable size.

As far as actual figures (in terms of cost) are concerned, no one has a clue and nor will they until these concepts are further developed. My sole argument is simply that a comparable size Raider will be more cost-effective than a Tilt-Rotor (and which I do not believe is a startling revelation) and which belief will be borne out by time alone!

We appear to be going in circles.

Nobody suggests a tiltrotor is more cost effective than an X2 at the particular size of S97. Thats precisely why sikorsky went and built that thing unsolicited; its at the max of the veritable X2 gross weight sweet spot.

For anything larger, especially FVL-M, the cost effectiveness of one over the other is entirely indeterminate (though we at least have data and a precedent of multiple tiltrotor machines), and thats assuming theres some magic blade recipe that can avoid tip interaction and self destruction at 60 foot diameters during manuever.

I find that startling. My argument is that your assessment that an X2 coax is more cost effective at any given comparable size has no basis. Where do you derive that axiom? What makes a given ABC coax inherently less complex or expensive than a tiltrotor? I contend the complexity is entirely on par.

I wonder if Eurocopter will compete. They are developing an advanced X6 medium helicopter and a militairy aimed similar sized helicopter using X3 technology.

Savoia- For sure, reducing IR is much easier with a conventional helo. The Comanche was a great example of how effectively it can be done. With a tiltrotor having tilting engines the long length (3 or 4 feet) of an engine exhaust IR suppression device can create ground clearance issues.

FVL won't enter service for at least another decade, and the model specs for each of the (4?) variants are still very much a work in progress. However, the BAA issued for the JMR phase I TD aircraft has requirements for DGW of 30,000lb or less, and a speed of 230+kts. Sikorsky had to push hard to reach 250kts with their X2 demonstrator design, which was optimized for only going fast. Once compound helo designs like X2 or EC's X3 make the compromises needed to meet FVL program requirements for payload, range, cabin volume, etc., they will be hard-pressed to attain 250kt speeds. On the other hand, tiltrotors can easily achieve 250kt speeds.

It looks as if there could be larger X2 technology on offer.

http://www.my-walls.net/wallpapers/2...42-485x728.jpg

Regarding Tilt-Rotor (TR) vs. ABC, there are a few things that need to be taken into consideration.

A TR is always going to have the penalty of the weight and area of the wing. Although you can have much more twist in the blades of a TR (because there is no need to design for the case where the blades are flying through the air sideways at higher speeds), the smaller the size of the air vehicle, the greater proportion taken up by the wing. On the other hand, once you stop hovering, you have the advantage of having the wing. Your propulsion source doesn't have to be your lift force as well, which gives you greater efficiency and performance. The ratio of hover to forward flight determines which is the most efficient. It's worth remembering that there were likely going to be two TR proposal for LHX until the Army reversed course and changed the specs so as to preclude a TR bid. From the information that leaked, it looked like the TR proposals would far outperform helos, even allowing for the hovering penalty.

A TR does offer lower risk. The XH-59 was pretty much a flop, and the X2, unquestionably an impressive achievement, was years late and has only demonstrated a few minutes at its design speed, whereas the XV-15 was routinely cruising at those speeds and above over 30 years ago.

A TR of course offers higher speeds. In the case of the V-280, the power driver was the 6K 95F requirement. With the power to do that, the 280 knot speed came as a byproduct, not a driver. It also offers longer range, because of that wing, and lower fuel burn, since it can run at proportionately lower power settings while wingborne. Self deployment is relatively easy for a TR, as was demonstrated when V-22s were suddenly deployed from Afghanistan to the Libyan theater. Self- deployment is especially important for them, since it looks like it'll be a easier (if the height permits it) to stuff an ABC vehicle in a C-17 than a TR.

The control system on a TR can be argued to be simpler since there is no need for a separate system to provide thrust. An ABC can fit in a narrower LZ, but it looks like a TR can fit in a shorter one, and there's no need to worry about what the aft prop is doing relative to obstructions and personnel. I can't tell if the arc of the proprotors on the V-280 extend beyond the nose. If you watch Sikorsky's videos on ABC operations, they show the propeller not being brought on line until airborne. This can have an affect on operations and will have a big impact on civil use of the concept for EMS, since one of the big concerns in that arena is the tailrotor and people near it. One other thing: With a TR, at least in the attack version, conventional ejection seats could be provided for the flight crew, not practical with ABC.

Final cost will depend a lot on how the gov't specs out the final requirement, and how much they add on to the desired capabilities and what they stuff into the contract. I simply do not believe that Sikorsky (or anyone) could deliver the Raider for $15 million. Like a TR, the flyaway costs of an ABC are going to be more than that of a conventional rotorcraft. Like a TR, you mke it up in the back end and needing fewer vehicles o accomplish your missions. If all they want is a conventional helo can do (watch what they do with the speed and range requirements), then neither advanced concept a chance. If they back off to 150-175 knots and lower range requirements, both of these technologies will go away.

As to why Bell left the 609, I suspect part of that was that they needed to concentrate all their resources on the V-22 program and that they hired certain people at senoir level (and they definitely needed new blood at that level) who were known not to be fans of TR.

One other thing: door gunners. While in an attack bird, remotely operated turrets are the way to go, in the assault mission they can not react fast enough, don't have the versatility and are much more expensive and trouble prone than guys in the doors. Consider a situation where the vehicle has landed to infil/exfil. The turrets are pretty much out of the picture. Also, when low and slow for whatever reason, you can do a lot more with door gunners than with a turret, especially if there are bad guys on both sides. It's no accident that USMC as decided to give priority to getting UH-1Ys over AH-1Zs.

Here's the B model :E

http://arthurguru.users.sourceforge....a/flv280b2.jpg


This is how they shoulda made it. The coat hanger design with the big prop (rotor) on top provides better auto capabilities. Point it forward and wheels retract and the struts supporting the gearbox become a lift producing airfoil.

Of course, I purport to know Evry Ting, he lives down the road.

Somewhere in Texas...

PR person: "Okay, so we've covered performance, range, technology and safety. Is there anything else we want to mention in the press release?"

Program manager: "No, I think that covers it. Let's go to press!"

PR person: "What about downwash. Do we want to mention downwash?"

Program manager: "Err...no. It's good as it stands, let's get it printed!"

PR person: "Are you sure? Isn't that something people will ask about?"

Program manager: "Well possibly, but it's not really something we want to draw attention to. The Valor's downwash is likely to be a bit greater than for other types. Let's just go with what we've got."

PR person: "Nah, I really think we should mention it. How about this..."

:E

I/C

Well at the DGW of FVL-M from the BAA and the apparent rotor radius / solidity from the models, the downwash should be well south of a V22/CH53/HH47 at the very least.

One of the reasons, aside from smaller size/weight, the downwash should be less is that at this size they don't have to worry about required safety clearance between the rotor arc and the island of the Marines' air capable ships. On the V-22, the rotor disc is smaller than optimum for that reason and so that an Osprey can fold up within its own length and width of the empennage.

Regarding the HH-47, now there's downwash! The UK found as their Chinooks approached the LZ in troop insertion operations, the downwash would actually set off shallowly buried land mines.

Door Guns etc
 

CC, I'd guess that those readers who have ventured into unfriendly LZ's concur with your point re door gunners ( assuming that this aircraft is tasked with that type of mission ).

Two other points will sooner or later come up when considering a TR for this replacement program, points raised by V-22 experience and resultant constraints in their flight manual:

1. Can the JMR TR operational requirement accept a 40 kt/ -800ft/min envelope restriction?
2. Same question, but applied to the no closer than 250 ft separation between aircraft in the LZ?

Thanks,
John

John,

Those restrictions are part of the original procedures developed prior to fully investigating the Osprey's relationship with VRS. In the Osprey, if one rotor goes into VRS, you get massive roll. In a twin rotor like the CH-46, you go end over end. Since then, and with the flight envelope testing they should have done back then, it's been found that the V-22 is less prone to VRS than most conventional helos, and more importantly is easier to recover (you blip the nacelles a few degrees and the proprotors are in "clean" air and out of VRS). They've also put a VRS condition warning on there which the crews consider more of a distraction than an asset. My understanding is that when an actual tactical situation requires it they do exceed that limitation. V-22s also do put out a bit of rotor wash, which unlike a conventional helo in forward flight, goes aft, not down. This is why there is a limitation of 250 ft. cockpit to V-22 ahead or avoid a 30 degree bearing off the tail when flying at same or lower altitude when within 250 feet. That's why you rarely see them fly in trail. It's not dangerous, just different.

In any case, the two questions you pose are specific to the V-22, its size and its less than optimum disc area (imposed becuase of the shipboard requirement and other original JVX specifications when they tried to make it another F-111--all things to all people). They are not a function of Tilt-Rotor technology itself. JMR/FVL is for a smaller, and more agile vehicle, so it's not likley that those procedures would be required.

Are V22 flight envelope restrictions relevent to a completely different aircraft with purported lower downwash (and therefore disc loading)?

Bell claimed that lower disc loading on the BA609 incresed max RoD before VRS. Seems like they planned on a 800ft/min "normal operation limit" based on some sort of safety factor, since VRS occured 2000-5000ft/min. This is an old article, so I wonder if flight testing has since expanded the "normal" RoD limits.

Staying flexible - and safe

History
 

CC, one interpretation of your note might be that the reasons cited at the time for the Marana and Eglin events were incorrect. Nonetheless, the accidents happened, and the descriptions of the flight situations involved in each weren't really out of the ordinary. As in, for instance, anyone ever get stacked up by the leader going into a hot LZ? Out of the 44K Vietnam pilots, there might be only 8-10 thousand in that category. Anyone ever get in the down wash of the ship in front while in formation? Same answer. Stuff happens and the JMR ought to be able to handle it. Is the argument that the JMR TR will be different, immune to V-22 proclivities? Bell will have to answer that query, and it will be interesting to see the response.

Not an anti-V-22 rant. It is a very fine machine, whose efficiency doing certain tasks is excellent. Every different rotor propulsion system has its strong points and compromises, be it single MR, tandem, coax, stiff coax, TR. Mission requirements will shine a bright light on which strong points and compromises make the most sense.

Thanks,
John

John,

Point I was making is that a TR is not more difficult or more dangerous, but it is different, and the tactics are as well. You've got those big proprotors blowing aft in forward flight, and the vector of that changes during transition as well. That's why they normally don't fly directly behind each other. The wake, if you will, is bigger than a comparable conventional helo.

By the same token, though, normally one conventional helo (or ABC) is not going to formate directly under another at close range, whereas with a TR you could, in forward flight.

As has been reported elsewhere, a refueling package is under study for the V-22. It already can normally refuel from a KC-135, which no helo can do, but it also has the speed to act as a tanker for fixed wings, for example USMC's F/A18s and AV-8s. It's still going to have its wake, but that's jsut something that will have to be planned for, just like it is for a -135, -130 or other tnaker. Of course, tanking operations won't be taking place at 500-100 ft. either! Flight testing will find out.

Accidents do happen, but they happen to everything. One of the more famous, for example, was the H-60 crash on Mt. Hood during a rescue attempt. From the video, it looked like a classic case of VRS, but could have also been a tail rotor malfunction.

It's not a matter of a JMR being immune to V-22 proclivities, they are differently sized aircraft performing a different mission. A JMR is not a V-22. It's a smaller aircraft with an optimally sized proprotor. Bell has already said they're looking at ways to reduce downwash in the hover, and that should also benefit the wake. As with anything, you have to make some choices. Do the speed, range and other advantages outweigh other factors that may be more problematical?

An ABC is going to have to answer the same questions, and it's going to have issues of its own. We have very little data on ABC, but a lot on TR. One of the things that came out in V-22 development is our computer models aren't as good as we thoght. We still need to do real flying to get answers and this will be true of ABC as well.

This isn't an anti-ABC rant, BTW. I'm simply saying that TR won't be the only advanced technology for which questions will have to be answered. Frankly, TR and ABC look like the only things to be viable to meet the Army's desires.

Reagan?
 

CC, now really! The Mt Hood to-do an example of VRS! As the Great Communicator might say: " There you go again". Not meant personally, of course, but the amount of misinformation promulgated in the wake of a few of the V-22 ooops events as regarding basic helicopters all being subject to VRS at the 40 kt/-800fpm boundary was simply unbelievable. Notice that one never caught the Project Pilot, Tom McDonald speaking thusly.

Anyhow, the Mt. Hood fiasco was a case of the pilot running the engines against the T4.5 limiter, drooping Nr, hence drooping tail rotor Nr as well. Rotor lift being a V squared function, the result was a descending right yaw spiral into the snow as the video showed. No mystery there.

It looks as though you at least are convinced that Bell now understands the shortcomings of the present TR design and has the answers as to how and why the Marana and Eglin events will be designed out of the next version. Have to say they have been really quiet about that aspect of things. And it is not simply a downwash velocity question alone, necessarily. When a few empty moments are available, do a hand calculation of the Marana blade loading number ( Ct/sigma ), allowing a reasonable addition for the increase required for the deceleration.

Not certain that I have read the JMR news correctly, but it appears that they want to have two competing prototypes, and I guess that means a fly-off. A very healthy and in the long run, a cost-effective way for the Army to know they have the right machine. The Army was quite thorough in the UTTAS fly-off, doing both an engineering and an operational comparison, using both their test pilots and a group of specially selected operational pilots ( including some with very little experience-on purpose ). Prior to the formal fly-off, there was a preliminary evaluation at Boeing and at Sikorsky, and that evaluation included power off landings ( not talking about power recoveries here ) for each of the three government pilots. Something else for the Bell TR folks to think about.

All of that in the future.

Thanks,
John

John,

I didn't say Mt. Hood was VRS, just that from the video it looked like it. Since I've never seen the accident report, I totally accept what you say...


Regarding a fly-off, I enthusiastically hope it is so. They always pay off in the long run, but because of the high upfront costs, they are now few and far between. In modern times we had UTTAS, AAH, A-X, ACF and then JSF (no I didn't forget ATF, that wasn't a flyoff-- 'nother story for a different time). I think we'd be well served by a flyoff between the two concepts, but I am not hopeful giving fiscal priorities.

There is an implication, I perceive, in your post that TRs can't autorotate to full landing. This is something that comes from the fact that the V-22 normally won't. That is true, because it wasn't required to. The requirement specified a survivable landing either through autorotation or through gliding to a short rolling landing. The V-22 team chose the latter. The larger the aircraft, the tougher an autorotation all the way gets to be to accomplish. A JetRanger does it nicely, the XV-15 was pretty good (although with only two they were not going to take it all the way), a CH-53, not so much. I suspect that if that is written in as a a pass/fail requirement, the V-680 will be able to do it, just like Sikorsky's JMR submission will.

I really hope we get a flyoff, but I'm not optimistic.

Fly-Off
 

CC, your mention of the AAH fly off brought to mind some memories. You will recall that SA built the S-67 with company funds, and later, in 1971, equipped it with an external stores ( rockets and/or aux tanks ) and armament system. F-111 head up display with low light level TV, a 3-barrel 20 mm turret run off a helmet mounted display, ins driven dig-map etc, all pretty good stuff for that time.

By the time the AAH RFP came out, SA was in good position to compete, but was not selected for the fly-off. While the UH-60 started deliveries in 1978, the AH-64 didn't reach the Army until six years later. I was down at Ft Rucker shortly after that, and had a look at the AH-64 , which had adopted a flying stabilator. The way it is/was mounted, it was easy to look at the installation and the actuator. Guess what: the actuator part number started with 70xx.... It was a Sikorsky Blackhawk stabilator part. Nothing illegal, of course, as the design belonged to the government.

Water under the bridge, and I supposed that DOD did not want too many eggs in one basket, but I always believed that if SA had been selected for the AAH fly-off, the SA candidate would have won and certainly been in the hands of the Army pilots a lot earlier than 1984.

Thanks,
John

Being a history buff the illustrations of the Valor reminded me of designs for tilt rotors produced by Raoul Hafner in the 1960s ,using the same basic engine/tilting gearbox design. Anyone else do similar?

Can't say I have ever seen anything from Hafner that approached a tiltrotor. Everything I recall from memory resembled an autogyro. Do you have any links/images?

Heli1: There were several tilt-rotor types subsequent to the 1955 Bell XV-3 including a number of 'tilt-wing' projects one of which was the 1964 NASA testbed the XC-142 which I always thought looked most interesting:



And if you wanted something where the just the rotors tilted then the ducted fan Doak VZ-4 was another interesting contraption: