New Bell battlefield product - Bell V280 Valor
"I guess the redesign is due the terrible experiences of the rotating engines on the V-22. After so many fatalities they reduced the vulnerability of the engine to ground-strikes but the lack of ground clearance is still a concern to operators and the jet efflux is less than ideal too. This design (if it works) looks much more appropriate for an aircraft you plan to land in the dark, on uneven terrain in a threat environment.
The internal bomb-bay looks interesting"
Excuse me, but exactly which crashes were due to the fact that the engines rotate? Which fatalities were caused by engine ground strikes?
Regarding the number of fatalities, the V-22 has had, the number is due to the fact that it can carry a lot of people, whereas say, an Apache carries two. Over half of all Osprey fatalties happened in one accident, and two accidents were responsible for over 70% of the fatalties.
The internal storage of missle launchers is probably partially to reduce drag at higher speeds. Sikorsky's concept of an X2 gunship a while back also showed internal storage of Hellfires.
Oh, don't call it a bomb bay. I believe one of the AF insisted-upon agreements regarding Roles and Missions mandates that Army helos can not drop bombs.
The internal bomb-bay looks interesting"
Excuse me, but exactly which crashes were due to the fact that the engines rotate? Which fatalities were caused by engine ground strikes?
Regarding the number of fatalities, the V-22 has had, the number is due to the fact that it can carry a lot of people, whereas say, an Apache carries two. Over half of all Osprey fatalties happened in one accident, and two accidents were responsible for over 70% of the fatalties.
The internal storage of missle launchers is probably partially to reduce drag at higher speeds. Sikorsky's concept of an X2 gunship a while back also showed internal storage of Hellfires.
Oh, don't call it a bomb bay. I believe one of the AF insisted-upon agreements regarding Roles and Missions mandates that Army helos can not drop bombs.
Last edited by Commando Cody; 18th Apr 2013 at 05:29.
Join Date: Jul 2006
Location: by the Great Salt Lake, USA
Posts: 1,542
Likes: 0
Received 0 Likes
on
0 Posts
CC... I suppose he is thinking of the crash(es) from hydraulic system failure due to line leaks in the nacelles... but those were due to chafing and vibration, and had nothing to do with the rotating joint.
A quick re-routing and proper securing of the lines against movement and that was fixed.
A quick re-routing and proper securing of the lines against movement and that was fixed.
CC... I suppose he is thinking of the crash(es) from hydraulic system failure due to line leaks in the nacelles... but those were due to chafing and vibration, and had nothing to do with the rotating joint.
A quick re-routing and proper securing of the lines against movement and that was fixed.
In that particular case, it also didn't help that a number of operational procedures weren't followed (including the decision to fly non-stop from Eglin to Quantico). In fact, the aircraft itself gave two warnings enroute, one of which dictated an immediate landing, which wasn't done (remember, it can land like a heloicopter). The leaks continued and when the nacelles passed through 44 degeres as they were tilted, proprotor gearbox fluid ran into the intake, ignited, and the gearbox started coming apart; the right engine surged and failed. The crosshaft functioned as advertised and the left engine began powering both proprotors. However, the intense heat and fire led to a failure in the shaft which then led to a hydrualic leak preventing control of the nacelles.
One of the probable causes was considered to be maintennace errors at Eglin resulting in incorrectly installed seals. So, while the tilting of the nacelles allowed fluid to run into the intake at that point, given what was going on, it's quite possible that something similar would have happened anyway had the aircraft remained in the air longer. In other words, it wasn't the fact that the nacelles tilted that caused the accident.
As you said, rerouting of lines, plus a titanium shield prevent a recurrence, but an incorrectly installed seal is still an incorrectly installed seal. Doing it right remains vital. Another Osprey was lost on its first flight because part of the flight control system was wired backwards, and so the aircraft would do the opposite of the commanded input!
A quick re-routing and proper securing of the lines against movement and that was fixed.
In that particular case, it also didn't help that a number of operational procedures weren't followed (including the decision to fly non-stop from Eglin to Quantico). In fact, the aircraft itself gave two warnings enroute, one of which dictated an immediate landing, which wasn't done (remember, it can land like a heloicopter). The leaks continued and when the nacelles passed through 44 degeres as they were tilted, proprotor gearbox fluid ran into the intake, ignited, and the gearbox started coming apart; the right engine surged and failed. The crosshaft functioned as advertised and the left engine began powering both proprotors. However, the intense heat and fire led to a failure in the shaft which then led to a hydrualic leak preventing control of the nacelles.
One of the probable causes was considered to be maintennace errors at Eglin resulting in incorrectly installed seals. So, while the tilting of the nacelles allowed fluid to run into the intake at that point, given what was going on, it's quite possible that something similar would have happened anyway had the aircraft remained in the air longer. In other words, it wasn't the fact that the nacelles tilted that caused the accident.
As you said, rerouting of lines, plus a titanium shield prevent a recurrence, but an incorrectly installed seal is still an incorrectly installed seal. Doing it right remains vital. Another Osprey was lost on its first flight because part of the flight control system was wired backwards, and so the aircraft would do the opposite of the commanded input!
Last edited by Commando Cody; 22nd Apr 2013 at 19:03. Reason: spelling
As with anything, there are tradeoffs.
Keeping the engines fixed means you don't have to design or cetify an engine to operate vertically or at intermediate angles. You also don't have to rotate such a large wieght, which allows you to have smaller nacelles, lighter rotating mechanisms, have a wider field of view from the sides and more ground clearance. You can also probably translate the proprotors more quickly.
On the other hand, with fixed engines and translating proprotors, you have a more complicated (and heavier) linkage between the power source and the proprotors. The safety crosshaft may be more complex in its totality. Your rotating mechanisms have to be more robust, since they are more complex.
You pays your money and you takes your chances.
Interesingly enough, Chitty-Chitty uses the original Boeing concept in their Tilt-Rotor proposal for LHX, with the engines in the central fuselage connected by shafts to rotating proprotors at the wingtips. Even more interstingly, the V-280 uses the tilting concept Boeing proposed for their version of the aircraft that lost to Belll for the XV-15!. I guess it really does all go 'round in circles!
Keeping the engines fixed means you don't have to design or cetify an engine to operate vertically or at intermediate angles. You also don't have to rotate such a large wieght, which allows you to have smaller nacelles, lighter rotating mechanisms, have a wider field of view from the sides and more ground clearance. You can also probably translate the proprotors more quickly.
On the other hand, with fixed engines and translating proprotors, you have a more complicated (and heavier) linkage between the power source and the proprotors. The safety crosshaft may be more complex in its totality. Your rotating mechanisms have to be more robust, since they are more complex.
You pays your money and you takes your chances.
Interesingly enough, Chitty-Chitty uses the original Boeing concept in their Tilt-Rotor proposal for LHX, with the engines in the central fuselage connected by shafts to rotating proprotors at the wingtips. Even more interstingly, the V-280 uses the tilting concept Boeing proposed for their version of the aircraft that lost to Belll for the XV-15!. I guess it really does all go 'round in circles!
Last edited by Commando Cody; 22nd Apr 2013 at 19:02. Reason: futher info
Thread Starter
Heli Expo 2016 my photos of V280 mock up
Hi guys here are my photos of V280 mock up in both utility and Dustoff fit,
cheers
and the DUSTOFF version
cheers
cheers
and the DUSTOFF version
cheers
Join Date: Sep 2007
Location: USA
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
One issue that comes to mind is how will the Army deal with the big difference in speed between the new generation of rotorcraft and legacy models like UH-60, CH-47, etc during transition?
Bell's XV-3 of 60 years ago also used tilting rotors, but the engine was located in the fuselage and drive shafts transmitted power to the rotors:
Thread Starter
First images prototype
Last edited by chopper2004; 31st Aug 2017 at 07:36.
Thread Starter
Achieves first flight
cheers
Join Date: Aug 2014
Location: New Braunfels, TX
Age: 70
Posts: 1,954
Likes: 0
Received 0 Likes
on
0 Posts
1. No, the SB>1 is not a rotodyne. The main rotor is directly coupled to the engines and the rotors are a contra rotating coaxial system. Completely different mechanically and aerodynamically than rotodyne.
2. The rotodyne was loud because it's rotor system was literally jet powered with jets at the tip of each rotor blade. No such jets in the SB>1.
3. The SB>1 uses an advancing blade concept. Simplified, this means the rotor blades (at speed) only generate lift while they are advancing forward into the airstream. The retreating blades go flat and do not generate lift. This gives the system a much higher top speed because the retreating blades do not stall as airspeed increases.
4. The rotor system is rigid and does not tilt forward to generate forward thrust. It only generates lift. The tail propeller provides forward thrust. This has the advantage that the fuselage stays level and the nose and weapons systems do not point downwards as the aircraft accelerates. Even the tiltrotor tends to drop its nose when accelerating. This level acceleration is a huge benefit in an armed helicopter.
Last edited by KenV; 19th Dec 2017 at 16:18.
Latest V-280 Valor flight test updates and videos.
https://www.defensenews.com/industry...-flight-tests/
https://www.defensenews.com/industry...-flight-tests/