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You Have to Love Numbers
You have to love numbers, especially when you only have half of the facts. The V-22’s 3000 lb. payload at ISA 10,000 ft. was for a 70 NM flight. The V-22’s takeoff weight at 10,000 ft PA is approximately 40,000 (per the brochure). As SAS stated, this is accomplished starting with almost 13,000 ESHP. For comparison the UH-60M will carry two times the payload (6000 lbs.) 70 NM using only 3988 ESHP and the CH-53E would carry 15,000 lbs of payload 70 NM on the same 13,000 ESHP.
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Dan, I make no editorial comment beyond that I did about the length/width diagram.
When was the last time a 46 landed cross ways on a LHA deck? I always thought they landed longways as ships by nature are long and narrow. I posted the link to the Bell-Boeing source so anyone can read what they say....and make their own observations about what they read. |
SAS, as you know, a comms and data handling suites are required kit in currently procured military helicopters. That is rooted in Command and Control requirements that get overlaid on most systems (so that the brass can better micromanage the battlespace :p ).
So too is all weather capability. Each of these required features adds weight. If all you want is a VFR only load picker upper (a stripped down pick up truck if you will), get an off-the-shelf KMAX. :) In other news regarding weight penalties, have heard that USN is going forward with aluminum gear boxes on Seahawks (a mod, I think) to begin within the next five years. This puzzles me, since gearbox positioning will (with the added weight) probably necessitate a non trivial retuning of the tail boom. This change of material is apparently driven by the corrosion bogey and the environmental bogey (chromate primers, for example, becoming environmentally non-PC). We'll see if this actually pans out. Anyone familiar enough with that angle in NAVAIR or Sikorsky to comment? If that's the case, I'd expect Knighthawks (CH-60S/MH-60S) to be backfitted. Don't think Army will pony up for Al gearboxes, not in the thousands, due to above cited fiscal realities. IOC on OH-58F: is it in the field? D is still alive and well. FWIW: my guess is that Sikorsky S-97 is a player for the follow on to OH-58D. |
Sas.
Need to go back to flight school. Often vertical lift approach from the side to their spot not down the deck. As to deck spacing their are no amphibs which can take two side by side running 46's next to the island. By deck configuration and geo probably more running V-22's can be fitted on a LHD than 46's. As to the high altitude capability of the UH-60 only this needs to be considered (and carrying only four crew): Looks like a prequel to Abbotabad except they had only a few feet to fall. The Sultan |
By deck configuration and geo probably more running V-22's can be fitted on a LHD than 46's. Sultan, More than a few of us have landed aboard ship and other decks and know the procedures for landing aboard. No one said anything about landing down the deck. It was said....the aircraft landed oriented fore and aft.....as compared to athwartships on the Gator carriers. If you use the diagram from the Guide....it shows the 46 overlayed on the 22...and what stands out is the 22 is as wide as the 46. When was the last time a 46 was spotted for turn-up and takeoff athwartships next to the island of a Gator Carrier? Simple point being made....perhaps beyond your grasp is the 22 is one very wide aircraft with rotors in the 90 degree position (helicopter mode) and there are certain areas of the Gator Carriers that are not much wider thus a reduced safety margin as compared to the 46. As to the Mount Hood crash....did you read the accident report for the cause of that? Perhaps you might and explain what that has to do with the Osprey's Guide Book figure of 3000 pounds payload for a landing in helicopter mode at 10,000 feet and enough fuel to fly 70 NM after takeoff? Do you know what the difference between an out of ground effect hover and a landing to the ground is? You grasp what trying to hover in a downward column of air is like on the side of a mountain such as Mt. Hood does for helicopter perfrormance? Have you even ridden in a helicopter? |
Aluminium vs Magnesium
Sikorsky gear box housings have traditionally been made from magnesium. It was determined that the housings were a weak element in the in the system. Gear boxes returned for repair or overhaul required housing replacements well short the overhaul cycle due to corrosion. In response to this Sikorsky began coating the outer surfaces to protect the housing against corrosion. This began in the early 1990s. I believe that it was either a substance called sermatech or rockhard. It was baked onto the outer surface as part of the manufacturing process. Aluminum would have a similar problem with corrosion in the salt environment. Any change may be driven by NAVAIR.
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Sas,
The 46 is an old Vietnam tail shedding not to good helicopter. Competent pilots have no problem landing the V-22. I do know well the difference between IGE and OGE. Hate to tell you, you eventually have to be OGE before or after IGE unless you want to get whacked by some R. Read Roberts Ridge. The Sultan |
The 46 is an old Vietnam tail shedding not to good helicopter. Competent pilots have no problem landing the V-22. I do know well the difference between IGE and OGE. Hate to tell you, The 46 is an old Vietnam tail shedding not to good helicopter. Competent pilots have no problem landing the V-22. I do know well the difference between IGE and OGE. Hate to tell you, you eventually have to be OGE before or after IGE unless you want to get whacked by some R. Read Roberts Ridge. Read Roberts Ridge. you eventually have to be OGE before or after IGE unless you want to get whacked by some R. As to your suggested reading assignment.....that is but one of the three books about that fight where very Brave Men flew, fought, were wounded, and were killed. In the past you attempted to denigrate the service of those folks and I pointed out how offensive that was. You sought at that time to suggest the Chinook Pilots had somehow contributed to the tragic outcome to that event. You were wrong then and you are doubly wrong now because you know better. The complete reading list of the three books in recommended order of reading: Robert's Ridge: A Story of Courage and Sacrifice on Takur Ghar Mountain Author: Malcolm McPherson 9780553803631 Lone Survivor: The Eyewitness Account of Operaton Redwing Author: Marcus Luttrell 978031607591 Not A Good Day To Die: The Untold Story of Operation Anaconda Author: Sean Naylor 9780425196090 The first two will tell the story of what happened on the ground. The third book will explain why it happened and what went so terribly wrong. Micro-managing combat from thousands of miles away is paramount to Murder! During Vietnam, Battalion Commanders flew overhead in their C&C helicopters and caused problems....but the modern version of that is absolutely ridiculous! |
Lonewolf.
I will not discard that idea so fast. Considering that the Osprey can do most of the jobs the actual fleet of 30 Coast Guard C-130, the CG could have a multirole platform that can patrol and operate at distances never seen before for a helicopter. Many other countries Coast Guard services use also maritime parol aircrafts for multitude of roles. I am not flying for the US Coast Guard but for the Spanish one however I believe the USCG would be more than happy to have such platfform that can fly farther, avoid weather better, hoist up a sizeable number of people and if equiped with mid air refueling equipment they can bring SAR anywhere and as long as it is needed. This is what I would call, "more punch for the buck" Now for less range range hoist operations, the Coast Guard have a fleet of HH-60, hh-65 and the C-130. In the age of "multirole" platforms, it doesn't seems to me such a bad idea to consider a platform that could make more and better. I would trade my Aw139 SAR any minute for an V-22. :O |
The Blackhawk and the Apache were both designed in the 1970s to meet Mil Std 1290. This was a very aggressive approach to ballistic and crash worthiness. Attributes included in Mil Std 1290 were: 32 fps crash attenuating landing gear, 42 fps crash attenuating airframe structure, fuel cells drop tested from 65 ft and a ballistic tolerant main airframe structure for up to 23 mm weapons. This capability was provided for at a significant weight penalty. The Blackhawk was procured to replace the 14 passenger UH-1H. The UH-1H’s empty weight was approx. 6000 lbs. while a similar 14 passenger Blackhawk has an empty weight of 11,500 lbs. Most of the weight difference was due to meeting Mil Std 1290. If you fast forward to the V-22 and Bell’s UH-1Y, both aircraft received wavers from Mil Std 1290 citing an inability to meet mission requirements at the higher weights required to meet spec. I do not believe that any aircraft subsequent to the Blackhawk and Apache have had to meet the requirements of Mil Std 1290. I am sure that the V-22 is a relatively robust machine but it cannot be compared to the Blackhawk or Apache for survivability. Secondly, strict adherence to full 1290 conformity was determined not to be necessary or cost effective. A systems approach to crashworthiness was used in the V-22 design to assure a high level of occupant crash protection for minimum weight. An estimated 90th percentile level (i.e., 36.5 ft/sec vertical velocity change) of crash protection was found to be most cost-effective for the advanced development model V-22 with a total crashworthiness weight impact of 1.4 percent DGW compared to 6 percent DGW for a MIL-STD-1290, 95th percentile (i.e., 42 ft/sec vertical velocity change) design. |
How was this decision arrived at? Where does the V-22 differ and what trade-offs offset the 1290 standards that would provide an equal or better level of protection?
It would be interesting to see the rationale used where differences exist just to understand the validity for the variance as there might be some very good reasons for it. As the Army opted out of the V-22 program very early on....is there a coorealtion between that decision and the Navy/Marine Corps/Air Force standards being in variance to that of the Army re crashworthiness standards. As the Air Force and Navy operate Blackhawks....there should be some commonality between the standards it would seem. |
V-22 Crashworthiness
Sans,
Are you saying then that unlike the UH-60, your rotors were not subjected to to 23 mm test hits? Thanks, John Dixson |
John,
Not sure what you mean by "my" rotors. I'm merely a tiltrotor fan, I dont own one. And, I didnt think I would need to go over this, but it sounds like you dont understand the concept of survivability as defined. Its a combination of susceptibility, vulnerability, and crashworthiness. On the susceptibility level particularly, the V22 is leap years beyond other rotorcraft assets in the field today, directly due to its flight profile abilities. And during LFT&E: 7.62 API, 12.7mm API, 14.5mm API, 23mm API and HEI, and 30mm HEI. 592 shots in all. DOT&E considered the MV22 as suitable for a medium threat environment. Extensive ballistic vulnerability live fire test program in which the threat weapons did not succeed in disabling the aircraft So I am not sure what you were getting at with the question? |
Read page 35 an on....particularly about Engine failures and the note that confirms the vulnerability of the 22 while in Helicopter mode and external load operations.
Also...the report stresses avoidance as a means of survivablilty which makes sense up to the point the aircraft encounters hostile fire close to the Landing Area....which ramps up the threat level to Hi-Intensity and also challenges the maneurablitly of the 22. Just reading from the linked report......not making any personal commentary. |
V-22 Ballistic Vulnerability
Sans,
I read the report and did not read a simple statement that the prop rotors were shot at by 23 mm shells and survived the hits. I know it was a very high profile test on our UTTAS design, and the pictures of the MR blade/spar after the hits were shown all over the place ( in fact the Army was quite specific about how the blades were to be fired at ). Judging by the various other pictures in that report, I'm wondering where the ballistic damage pictures are. Thanks, John Dixson |
Read page 35 an on....particularly about Engine failures and the note that confirms the vulnerability of the 22 while in Helicopter mode and external load operations. I seemed to read much more into the following comment, which seemingly flies in the face of the low altitude hover survivability argument against the V22: Page 35 Due to its high power, the ability of the V22 to survive single engine failures during low altitude hover is excellent -- better than the legacy transport helicopters it replaces. |
I read the report and did not read a simple statement that the prop rotors were shot at by 23 mm shells and survived the hits. I know it was a very high profile test on our UTTAS design, and the pictures of the MR blade/spar after the hits were shown all over the place ( in fact the Army was quite specific about how the blades were to be fired at ). Judging by the various other pictures in that report, I'm wondering where the ballistic damage pictures are. Extensive ballistic vulnerability live fire test program in which the threat weapons did not succeed in disabling the aircraft |
V-22 Reports
Sans,
Color me skeptical, I guess. The prop rotors should have been fired at along the critical axis, and the the specimen put in a test rig and subjected to flight light loads, derived from flight test. No chance of seeing the relevant part of that other report, I guess? I'm not saying Bell/Boeing didn't do some testing, just that the grammar in the report you provided reads more like marketing material. I'm also skeptical about the assertion that the low hover HV capability is superior to legacy machines. I have an older copy of the V-22 HV curve marked Change 1. Do you have access to the current chart? The chart I have shows the low hover limit for 12 fps at 10 ft. Thanks, John |
Quote:
Due to its high power, the ability of the V22 to survive single engine failures during low altitude hover is excellent -- better than the legacy transport helicopters it replaces. I guess it depends on which legacy helicopters you are going to use for comparison. The CH-53E loses just 24% of its installed ESHP with single engine failure power. (2X 5000 ESHP two engines operating vs 13110 ESHP with all three operating). Similarly, the Blackhawk has a robust contingency power rating available for emergency OEI conditions. I believe that the Blackhawk loses only 36% of its duel engine power available. JD may be able to help me out here on the specifics of the Blackhawk OEI capabilities. In the case of the CH-53E two engine fly away is capability is present under most mission scenarios. |
John
Not sure where you might be able to find the previous report. Only took 5 minutes of google searching to find the pogo copy, though, so it might be out there. Here is a good overview of multiple programs http://www.jasprogram.org/images/arc...010_summer.pdf Ballistic Vulnerability Reduction Figure 3 includes a listing of the wideranging vulnerability reduction techniques that have been utilized to meet the vulnerability reduction of the V-22 airframe. These technologies range from inherent structural design requirements such as multiple load paths and allowable load requirements to active fire suppression systems to prevent sustained fire in the aircraft. All the technologies were extensively tested at the component and subsystem level and demonstrated in flight aircraft structure configurations. This included ballistic testing with aircraft light load levels and for fire suppression testing with flight air flows for representative conditions and confirmation of system sizing. |
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