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Boeing Vertol BV-360 or "Boeing 360"

F-14D

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Abraham Gubler said:
On tandem tilt rotors the whole point was in context of the LHA flight deck width limit reducing the size of the V-22's side by side tilt rotors to the level where they were overloaded and subsequent enormous effort to make that aircraft fly. If said tilt rotors were tandem (one behind the other) then they could be much bigger without coming close to the width limits of the LHA (see attached picture drawn with very fine art skills...). Of course there are all sorts of other problems such a configuration would generate but the core issue of rotor lift for footprint would be solved.

On the Model 360 Boeing developed a lot of new technology that went into the RAH-66, CH-47F and the V-22 - so far. So their return on Model 360 investment has been considerable. Sure no one ordered the CH-46X (a designation sometimes associated with the M360) but as a technology test bed it was a success.
Hey, your art skills are better than mine!. With the tandem, you are going to run into some complex issues wherein the aft proprotor has to change from a tractor to a pusher and vice versa during the transition. And you do run into the situation in hostile terrain that your rotors extend ahead of the nose and more importantly aft of the rear (where they aren't visible), but you do gain the width benefit. The V-22's less than optimum rotor size does not cause it to be only be able to stagger into the air, but it does reduce efficiency in powered lift flight.

Your point on the 360 is well taken and one I totally agree with, BTW. That's why I was reacting to the referenced statement that the 360 almost broke Boeing Helicopters-- if it was really that bad, they'd just stop it; there was no gov't development contract that forced them to keep going. They clearly felt the technology gain was worth it...
 

Abraham Gubler

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F-14D said:
Hey, your art skills are better than mine!. With the tandem, you are going to run into some complex issues wherein the aft proprotor has to change from a tractor to a pusher and vice versa during the transition. And you do run into the situation in hostile terrain that your rotors extend ahead of the nose and more importantly aft of the rear (where they aren't visible), but you do gain the width benefit. The V-22's less than optimum rotor size does not cause it to be only be able to stagger into the air, but it does reduce efficiency in powered lift flight.
And that's just the start of the list... Having the entire nose of the aircraft within the propeller wash is going to create all sorts of problems. Then there is engine maintained, cross shafting (forget about it), etc.

Which raises the next inter-related point. Why is the tail wagging the dog? In this case why is the LHA proscribing the dimensions of the JVX?

It’s like the crazy idea that Army ground combat vehicles need to fit into a C-130 for airborne tactical manoeuvre. Of course with a maximum load a C-130 can fly from here to nowhere significant and how do you offload a battalion or company at an austere airport from C-130s in anything less than a few days and since when is the air force going to through away C-130s to deliver a single tank? The solution is to design the tank tactical airlifter to the needs of the optimum ground combat vehicle. Something like the Boeing ATT Super Frog able to carry a ~50 ton vehicle and offload it on a field ~2,000km away from your base rather than offload a 18 tone vehicle at an austere airport ~500km from your MOB.

The same applies to JVX. The V-22 should have been designed with the >43 foot rotors that the mission required and the next classes of amphibious ships designed to support this width (>100 feet rather than >80 feet). Sure this may have limited your operation of V-22 from island side flight decks of the LHAs and LPHs. But they could always revert to original style flight deck operation with the V-22s spotted forward and aft of the island along the centreline. Which would probably enable at least six to launch and land simultaneously per LHA/LPH. The new LHDs would be designed with the flight deck width to enable the full length to be covered by V-22 spots offset to port.

That’s the dog wagging the tail. The dog being the thing that engages the enemy rather than the supporting complex.
 

F-14D

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Abraham Gubler said:
F-14D said:
Hey, your art skills are better than mine!. With the tandem, you are going to run into some complex issues wherein the aft proprotor has to change from a tractor to a pusher and vice versa during the transition. And you do run into the situation in hostile terrain that your rotors extend ahead of the nose and more importantly aft of the rear (where they aren't visible), but you do gain the width benefit. The V-22's less than optimum rotor size does not cause it to be only be able to stagger into the air, but it does reduce efficiency in powered lift flight.
And that's just the start of the list... Having the entire nose of the aircraft within the propeller wash is going to create all sorts of problems. Then there is engine maintained, cross shafting (forget about it), etc.

Which raises the next inter-related point. Why is the tail wagging the dog? In this case why is the LHA proscribing the dimensions of the JVX?

It’s like the crazy idea that Army ground combat vehicles need to fit into a C-130 for airborne tactical manoeuvre. Of course with a maximum load a C-130 can fly from here to nowhere significant and how do you offload a battalion or company at an austere airport from C-130s in anything less than a few days and since when is the air force going to through away C-130s to deliver a single tank? The solution is to design the tank tactical airlifter to the needs of the optimum ground combat vehicle. Something like the Boeing ATT Super Frog able to carry a ~50 ton vehicle and offload it on a field ~2,000km away from your base rather than offload a 18 tone vehicle at an austere airport ~500km from your MOB.

The same applies to JVX. The V-22 should have been designed with the >43 foot rotors that the mission required and the next classes of amphibious ships designed to support this width (>100 feet rather than >80 feet). Sure this may have limited your operation of V-22 from island side flight decks of the LHAs and LPHs. But they could always revert to original style flight deck operation with the V-22s spotted forward and aft of the island along the centreline. Which would probably enable at least six to launch and land simultaneously per LHA/LPH. The new LHDs would be designed with the flight deck width to enable the full length to be covered by V-22 spots offset to port.

That’s the dog wagging the tail. The dog being the thing that engages the enemy rather than the supporting complex.
Couple of thoughts, although we are getting away from the Boeing 360.

When JVX was first mooted, no one guessed that Cheney would cancel it and Clinton would delay it. So, said vehicle was designed to operate from existing platforms. Since there were provisions in the design for the other services (including the stillborne Army version), you ended up with a heavier vehicle than you would have had for pure HXM, and on a lighter aircraft you could have smaller proprotors. However, although JVX was heftier, it still had to meet the Marines' requirement for shipboard compatibility. You see this in other multi-service aircraft: F-35, CH-53, F-111 (ooooo, bad example), etc. The F-14 would have benefitted from being two feet longer, but that would have an impact on how many you could park and move on the flight and hangar decks The V-22 is not as efficient with the 38 foot discs as it would be with 43, but it's good enough to meet the need. As I said, there may have been different proprotors on the Army V-22 (I'm not sure), but that version didn't happen.
 

yasotay

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I'm sure that F-14D has far more information on the issue, but the Army JVX did have larger prop-rotors and was not near as complex having no need for all of the folding apparatus that has to go on the MV-22 and CV-22. I am sure that there are ongoing efforts to make the next Block of CV-22 better. I would bet on new rotors, changes to hydraulics and electrical systems.

As to tandem rotor helicopters, I don't think that Boeing has completely tossed it. Remember that they promoted a tandem for the JHL effort originally. I suspect as a core competence it will remain one of their first considerations for any new rotorcraft, at least cargo rotorcraft. So, much of what they learned from the 360 effort remains available to Boeing if a conventional tandem rotor aircraft is called for in the future.
 

F-14D

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yasotay said:
I'm sure that F-14D has far more information on the issue, but the Army JVX did have larger prop-rotors and was not near as complex having no need for all of the folding apparatus that has to go on the MV-22 and CV-22. I am sure that there are ongoing efforts to make the next Block of CV-22 better. I would bet on new rotors, changes to hydraulics and electrical systems.

As to tandem rotor helicopters, I don't think that Boeing has completely tossed it. Remember that they promoted a tandem for the JHL effort originally. I suspect as a core competence it will remain one of their first considerations for any new rotorcraft, at least cargo rotorcraft. So, much of what they learned from the 360 effort remains available to Boeing if a conventional tandem rotor aircraft is called for in the future.
I believe the Army was going to have different proprotors, at least in the SEMA birds, because of the requirement to cruise at 30,000 feet. You can see a similar situation if you look at the rotors of Army AH-1s vs. Marines AH-1Ws. They Army birds can HOGE at a much greater altitude than the Whiskey. Marines didn't care about HOGE at high altitude, that's not their environment. What they needed was to be able to continue to lift their full load at lower altitudes as the temperature rose and the -1W's rotor was optimized for that.

My understanding is that the wing would be mounted similar to the Marines' version, for cost reasons, but would not fold, which would save weight and a lot of maintenance (of course larger proprotors would also be an issue here). This is like USAF F-4s. On the C/D models, the wing folds and mechanisms were the same as on Navy Phantoms. The hydraulic actuators were removed on the F-4E/G, but the folds remained the same.

You know, if the 360 had somehow been developed to meet another need, unlike the CH-47 it might have made a great CSAR bird.
 

RAP

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Boeing 360 helicopter display model

http://www.ebay.com/itm/OLD-BOEING-MODEL-360-EXPERIMENTAL-TANDEM-ROTOR-HELICOPTER-CONTRACTOR-DESK-MODEL-/371971743495?hash=item569b3e5f07:g:d3oAAOSwcgNZM7wN
 

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