Wednesday, August 16, 2017

MV-22 Assault

The Marine Corps has been rapidly moving away from the traditional over-the-beach amphbious assault using landing craft to an aviation based assault concept using helos and MV-22’s.  ComNavOps has questioned the feasibility of this approach in numerous posts.  Let’s continue to examine the issue.

Defense Update website has a fascinating article describing numerous helo shootdowns.  Here are some numbers to get a feel for the magnitude of the problem.

“The U.S. Army has lost more than 120 helicopters in the war on terror, about 25 percent of them due to enemy engagements. According to recent official statistics, some 57 U.S. helicopters had been downed in Iraq until Feb. 4, resulting in 172 deaths, or about 5.5 percent of total American deaths since the conflict began in March 2003. According to U.S. Army General Simmons, the U.S. Army has lost 29 helicopters to enemy fire since March 2003.” (1)

How have these losses occurred?

“The majority of the firefights involve machine-gun and heavy-machine-gun fire, categorized as up to 23 mm, Simmons said. But, he added, some surface-to-air missiles, such as SA-7s, SA-14s and SA-16s, have been used to shoot down Army helicopters.“ (1)

While that may seem like a lot of losses for a semi-war, we have to recognize that helos have heavy workloads and fly a lot of hours and missions.  It is simple statistical probability that some will be shot down or damaged.

“Army helicopters average 100 enemy firefights monthly and are hit about 17 times a month. Most times the helicopters are able to fly back to base. Simmons said that is a testament to the quality of pilots, crews and equipment. The number of flight hours for the Army has nearly doubled in the past two years. In 2005, pilots logged about 240,000 hours. This year, Simmons said, he expects that number to reach nearly 400,000 hours. In 2006, pilots and crews flew 334,000 hours.” (1)

On the other hand, highly sophisticated helos should be quite successful against ill-equipped and ill-trained terrorists so any losses should be viewed with a degree of alarm.

What about countermeasures and defensive tactics?

“As result [of losses due to SA-18 type missiles], U.S. military helicopter pilots in Iraq tried flying low and fast, hoping to elude heat-seeking missiles fired by insurgents. But the insurgents responded with heavy weapons such as machine guns and rocket-propelled grenades, and the loss rate of American helicopters soared. So the pilots went high again and insurgents replied with lethal surface-to-air missiles. The vicious circle continued.” (1)

It’s not just newer surface-to-air (SAM) missiles that threaten helos.

“What is still more vexing to Helicopter pilots flying combat missions in Iraq is the constant threat from RPGs. U.S. military helicopters are equipped with long-range sensors and devices to jam radar and infrared technology, but they have proven vulnerable to intense gunfire, as well as rocket-propelled grenades.“ (1)

American pilots learned to fear good old fashioned barrage fire in Vietnam and the threat remains just as valid today as then.

Helicopters are particularly vulnerable when landing.  At that time they have no choice but to be low, slow, and non-maneuverable – they have to be in order to unload and to maintain flight control in the inherently “unstable” hover mode.  Consider what this means for aviation assault.

“… pilots …  "yank and bank" in a corkscrew motion when approaching a dangerous or "hot" landing zone, dropping with a gut-churning, nose-high descent. Hovering, a helicopter is at its most vulnerable… Brig. Gen. Robert Milstead, a Cobra pilot who recently returned from commanding a Marine air wing in Iraq claims: "Above about 2,500 or 3,000 feet you are out of small arms range but you've got to worry about the MANPADS threat, by all means avoid 500 to 1,000 feet because you're hanging out there like a grape, to be picked!"

This is bad enough for conventional helos but now consider the MV-22, envisioned by the Marine Corps as the backbone of aviation assault.  The MV-22 is not a helo.  It is a conventional aircraft that can temporarily, carefully, and cautiously enter helo/hover mode for brief periods while landing and taking off.  However, it is even more unstable than helos while in hover mode and cannot even remotely “yank and bank” during its landing.

In Vietnam, helo assault pilots learned to come in fast and hard, hit the ground in a tightly packed grouping, unload the troops in seconds, and haul out.  Now, watch any MV-22 “combat” landing video – there’s plenty on YouTube.  MV-22 landings are the complete opposite of what I just described.  The MV-22 requires large spaces – there will be no such thing as tightly packed landing groups, slow, careful maneuvering to deal with the inherent instability of hover mode and the poor visuals that the pilot has, and a relatively slow rate of unloading.

UH-1 Huey Assault

We previously discussed helo operations and losses in Vietnam where over 5000 helos were destroyed – a 43% loss rate (see, “Helo Assault”).  Consider the helo assault losses in Vietnam and then compare the physical size and performance of the UH-1 Huey versus the MV-22.  As a reminder, here are a few relevant specifications.

UH-1 Huey
-          Size:  57 ft long rotor tip to tail
-          Fuselage:  20 ft x 8’7” approx fuselage =  170 sqft
-          Troop Capacity:  around a dozen troops with wide exits from both sides

-          Size:  57 ft long x 85 ft rotor tip to tip
-          Fuselage:  50 ft x 15 ft approx fuselage = 750 sqft
-          Troop Capacity:  around two dozen troops with one exit at the tail

As seen, the MV-22 fuselage, the major targeting mass, is 4.5 times the size of the Huey when viewed in profile.  Combine that with the greatly reduced combat landing performance of the MV-22 and the loss rate in a contested assault will soar even over the shocking Vietnam loss rates.

MV-22 - Compare the Size to the Huey!

Let’s look at more recent evidence.  Consider the Karbala battle:

2003 – Karbala, Iraq – During Operation Iraqi Freedom, ambush barrage fire from the Iraqi Medina division routed 31 US helos of the 11th Regiment / 3rd Infantry Division.  Two helos were lost (one to a non-combat crash) and all but one were heavily damaged.  The helo unit was effectively wiped out.

Recognize that all these helo losses were under best-case scenarios where the US had total control of the sky and the enemy was generally ill-trained and ill-equipped.  What will losses be against a peer, under contested skies, and against well trained troops with state of the art weapon and sensor systems?

So, with all that said, I have to pose the question,

How are we going to conduct a successful helo/MV-22 aviation assault?

The answer seems pretty obvious:  we aren’t.

If that’s the case, why are the Marines basing so much of their doctrine and acquisitions around aviation assaults?


(1)Defense Update website, “Deadly Scourge of the US Helicopter Pilots in Iraq”, Colonel David Eshel, 2007,


  1. Good article. Would like to add a few things:
    The number of Marines an Osprey can carry diminishes very quickly with landing altitude and air temperature down to less than half in hot Helmand like conditions meaning you will be more vulnerable because you need many more sorties.
    Second point is the time in transition the aircraft requires is extensive and it is vulnerable. The Osprey has to fold up its belly gun when transitioning also and cannot use the ramp gun because troops are getting ready to go out.
    Hover mode for fast roping is scary and is a continuous forward creeping motion.
    On a positive note, the ramp entry and exit is awesome for getting vehicles like the MRZR in and out and makes the platform especially suitable for Recon or bringing 120mm mortars.
    Also, it travels very fast over long distances (for a helicopter) and there is nothing else with rotors that can come anywhere close in range if you have to assault far inland.
    Overall, it is good for bringing parts of the assault on shore, but you need to have a semi-permissive area to land.

    1. Very nice comment. I agree about the semi-permissive landing environment and I would go a step further and say a completely permissive area is needed. I just can't see the MV-22 conducting a successful opposed landing. We saw what happened to the Hueys and this would be worse.

    2. The CH-47G and CH-53E have more range than a V-22 with the same payload. V-22 range figures are distorted as they assume it carries special fuel tanks inside the fuselage. Helicopters can do that too to extend range. And V-22 range stats assume it flying through thin air at 24,000 feet with no passengers and pilots wearing artic gear and masks, but that is not allowed for more than an hour due to safety issues with hypoxia. But it boosts range stats on paper as our Navy will learn when the COD CMV-22s arrive and can't fly nearly as far as claimed!

  2. Compared to a "regular" landing, hitting the beach with ground forces, the assault with MV22s has a bigger problem because of it's size and tactics used, how hard is it for the enemy to figure out where the MV22s are going to land? Even the extra distance doesn't help much, the last couple of SFs raids in Africa, weren't CV22s used and were seriously hit? Didn't we lose in Yemen?

    This is a disaster waiting to happen.....

    1. Official Marine videos never show a V-22 landing in an LZ (or the edit out the slow part) because it looks stupid. Here is one from a personal cam. It must land slow because a rapid descent may cause VRS causing it to roll and nose over.

      A helo can approach much faster and flare to brake and plop down.

    2. Compare Osprey landings to what the XC-142 was doing in the 1960s. There in one clip in there where the tiltwing does a rapid pull out on a landing approach.

      The XC-142 design has the advantage of being a real plane that is capable of VTOL, instead of being a strange hybrid of a plane and a helicopter and more mechanically complex than either.

    3. Uh, I think it's debatable whether or not a rotating wing and four or more interconnected props is simpler than two interconnected props on rotating nacelles.

      And from Wiki regarding the XC-142:

      "During the prototype development the Navy decided to exit the program. They were concerned that the strong propeller downwash would make it difficult to operate. Their existing HR2S fleet had a ground pressure of about 7.5 psi (500 hPa), and proved to blow people about on the ground and stir up considerable amounts of debris. The C-142 was predicted to have an even higher loading of 10 psi (700 hPa), which they believed would limit it to operations to and from prepared landing pads and was therefore unsuitable for assault operations."

      Using Wiki's numbers for the disc loading of the V-22 at 47,500 lbs (20.9 lbs/sqft), The V-22's disc-loading works out to about 0.145 psi. At the same weight as the V-22, the CH53E's disc loading is about 9.7 lbs/sqft or 0.067 psi. There is NO free lunch. Pick a design point along the pure-fixed-wing/pure-rotary-wing continuum and decide whether or not the tradeoffs are worth it.

      You may not believe it, but the people that design these machines DO have a clue what they're doing.

      - Gripen

    4. This comment has been removed by the author.

    5. It looks like the units in used in Wikipedia are wrong for the HR2S and XC-142. I think they are supposed to be psf. Empty, the XC-142 has a disc-loading of about 7.5 psf (22,600lbs over four 15.5 foot props, discounting the tail rotor). So, 10 psf seems about right at a useful takeoff weight. Let's keep in mind the difference in size though. Discounting the tailrotor, the XC-142 has a disc area of about 3,000 square feet over a 67.5 foot wingspan wheres the V-22 has disc area of 2,268 square feet and a wingspan just shy of 46 feet. Man, that XC-142 must have been held together with chicken wire to come in at 22,595 lb empty. I wonder what a similar aircraft would come in today with all the modern extras. I'm always kind of amazed how lean those old aircraft could be.

      Regardless, the XC-142 configuration clearly has it's own unique characteristics for good and bad. I can recall some concepts that proposed replacing the c-130 with a similarly sized tiltwing aircraft.

      It's also important to remember that tiltrotors also have the option of doing rolling takeoffs and landings to gain lift from the wing on prepared and semi-prepared landing strips. And some tiltrotor concepts have outboard wing segments that rotate along with the proprotors while the inboard wing segments remain stationary in a sort of hybrid tiltrotor/tiltwing configuration. See, for example, the V-247 concept, among others.

      - Gripen

    6. Also, the graph here is instructive:

      - Gripen

  3. I said semi-permissive because the MV22s that received small arms fire in Afghanistan kept flying; sometimes impacts were unnoticed until maintenance, but this SAF was nothing bigger than AK or PKC fire.

  4. MV-22 is going to need a escort who can keep up with it.
    I guess that time will come when its time to replace the AH-1Z.

    And another tough, just how noisy is the V-22 i mean really its important .
    On a pitch black night with no moonlight you almost cannot hear a UH-60 approaching until its very close ( i know from experience ;)

    I suppose tho two Big propellers on the V-22 will make a lot of noise even during the night you will be able to hear it from far away.

  5. A radar guy told me the V-22 with its big forward rotors has a radar image the size of a 747. Also, V-22s are required to land 250ft apart to prevent downwash from one V-22 flipping another over. V-22 hover performance is poor, and while a connecting drive shaft can power both rotors if an engine is lost, it cannot provide enough power to hover (as seen the recent crash in Hawaii). And of course if a gearbox freezes or rotor is lost, the other rotor will flip it over.

    Yes, the V-22 is some 40% faster than helos, but when approaching an LZ it must land even slower. I think a couple modern AAA guns can shoot down a dozen landing V-22s in two minutes. Let's not even discuss SAMs because it seems Marine Generals don't know they exist.

    1. Then we shouldn't use C-130's or C-17's for airborne operations either because of their radar signature.

      And, I'm not sure of that 250 ft separation distance either. I found a video of 3 MV-22's landing on the USS Bataan rather close together. Maybe 60-70 feet apart.

    2. Yes, airborne ops against an enemy with modern air defense is just stupid. Have you seen the insane videos of huge C-17s flying low at 300 knots to drop paras. An AK-47 could down the entire aircraft!

      Your V-22 video shows only one taking off and landing at a time while the others idle. The V-22 has a unique problem in that its rotors are not attacked to its fuselage. One rotor can encounter wake turbulence causing a snap roll. The computer usually corrects, but not always, like when the CV-22 flipped over and crashed in Florida. Google for info on that case, the other V-22 was over 250ft away, the limit in NATOPS.

      This is why there is no civilian tiltrotor in service, it can't pass the FAA. Bell had one going but sold it to the Italians who failed, and Bell built a new medium lift helo.

      After years of marketing, they only sold 17 V-22s overseas, to the Japanese, everyone else chose the CH-47F, which cost half as much to procure and maintain and can pick up three times more than the V-22, 24,000 lbs per Boeing.

      And the CH-47F is much smaller than the V-22 in empty weight, and has three machine guns, and will not roll over trying to hover. The Marines never had more than 10 V-22s in Afghanistan and only used them for PR stunts and airfield to airfield hard deck missions. The SpecOps command only had them there a few months and sent them home after one crashed trying to hover. It has ordered more H-47s, which it chose for the OBL mission.

  6. Well, the V-22 sure is a technological marvel and a cornerstone in VTOL technology , but probably the X-22 designation would be more suitable i.e. to remain just a advanced technology demonstrator .

    That brings me to a wider question

    What is it with this " UNIQUE MARINE" requirements that rip off the budget with billions.
    Ok, if its for something minor like small arms systems like the M27 rifle and other "marine only" tacticool stuff i can understand

    But for aviation c'mon first thing that comes to mind is the UH-1Y transport helicopter.. what was the problem of just adapting standard USN Seahawks with minor modifications and call it a day and save some million by the way .

    Same with the AH-1Z if they were smart they should adopt the Apache decades ago.. British,French and Russians use adopted land attack helicopters designs from they're amphibs.

  7. I concur that all evidence suggests that large-scale aviation assaults are infeasible in contested environments and inadvisable in even semi-permissive environments. But I think that this is true for ALL rotary wing aircraft. Analogously, fellow readers, see: . I disagree, however, with the characterization of the V-22.

    For starters, let’s be clear about the characteristics of the aircraft. The V-22 is the cargo box of a CH-46 on an aircraft of about the same weight and power as a CH-53E that cruises 90 kns faster (maxing out at 105 kns faster on the deck) than the CH-53E and flies somewhere between 240-340 nm farther than the CH-53E (using Wikipedia’s numbers) at the expense of an additional 13 passengers or 10,000 lbs of internal cargo capacity versus the CH-53E. Wiki puts the flyaway cost of the V-22 at about $71 million in FY2015 and estimates the flyaway cost of CH-53K at about $87 million (also for FY2015, I think). However flawed the concept of an over-the-horizon amphibious assault may be, it seems like there is an argument for acquiring V-22s over CH-53E/Ks in this scenario (personally, I’d prefer the V-22 AND a navalized, up-engined CH-47 with the rotor-folding mechanism of the CH-46 over either the 53E or 53K). If you don’t need the speed and range of the V-22, it would make sense to acquire the CH-53E/K on a one-for-one basis or a greater number of upgraded CH-46s (see the Boeing Model 360), an S-92 derived airframe, or AW101s. I’m sure you’ll agree that the CONOPS should decide the types/mix of aircraft acquired.

    I don’t think the UH-1 comparison is relevant other than to show that an aircraft larger than the UH-1 is more vulnerable to ground fire, which is true of the UH-60, CH-46, CH-47, and CH-53, and doesn’t account for the benefits of the extra speed, power, and rate of climb on the way into and out of the LZ that the V-22 possesses.

    With regards to the “combat-landing performance” of the V-22, I don’t see much evidence of a deficiency versus similarly sized aircraft (i.e., the CH-53 and Ch-47):

    And look at how quickly the MV-22 is on top of the objective! Okay, so it spends a good amount of time in ground effect before touching down, but this seems typical of almost all rotary-wing landings, regardless of airframe:

    It’s also important to note the wings of V-22 provide ENORMOUS aerodynamic drag that can be used to slow/descend the aircraft from high speed/altitude onto an objective in a minimum-radius turn.

    And the CV-22 looks pretty good when flown relatively aggressively:

    And I don’t think that a lack of maneuverability is inherent to tilt-rotor aircraft:

    The CV-22 seems about as tough as any other helicopter too:

    Are there disadvantages that come with the high-disc loading and transverse prop-rotor arrangement of tiltrotors (e.g., greater turbulence requiring greater separation between aircraft and susceptibility to roll-overs)? Of course. But there are advantages too. Ultimately, a MIX of aircraft will be appropriate.

    - Gripen

    1. To replace the UH-1 and UH-60, I believe we should procure a SB>1 Defiant-type airframe that would carry squad-sized elements faster and farther than the legacy airframes while maximizing low-speed maneuverability. These might be your best best for contested assaults.

      While I think the V-280 has enormous potential, my belief is that you gain more from the tilt-rotor arrangement in larger aircraft than are expected to travel farther and faster than typical of a 10,000-20,000 lbs aircraft. I would replace the V-22s with a similarly sized, or maybe even slightly larger, V-280-derived aircraft. It’s important to note that the V-280 has proportionally bigger and thinner wings than the V-22 and proportionally bigger prop-rotors than the V-22. The V-22 is a sub-optimal tilt-rotor design because it had to fit within the prescribed dimensional requirements of a CH-46 replacement, which it really isn’t. It’s also been found that the flutter than necessitated the slight forward sweep of the V-22s wings is a non-issue. The V-280 does not have this sweep, and as a consequence, reduces complexity and saves weight in the structure of the wing and the cross-wing driveshaft. Combined with the fixed engines, I believe my notional “Osprey II” would represent a significant improvement over the V-22.

      Additionally, I would cancel the CH-53K because the main and tail rotor arrangement is too inefficient in an aircraft that should be optimized for maximum internal volume and maximum external loads. An upgraded and enlarged CH-47 with the installed power of the CH-53K and four or five rotors per mast would CRUSH the 53K. The 53s fold SEVEN rotors for stowage. I can’t think of a reason why an 8 or 10-bladed tandem rotor helicopter couldn’t fold it’s rotors like the CH-46 when aboard ship.

      - Gripen

    2. I meant to link to Mr. Bustamante's guest post in my original comment, "Analogously, fellow readers, see:"

    3. "And look at how quickly the MV-22 is on top of the objective! Okay, so it spends a good amount of time in ground effect before touching down, but this seems typical of almost all rotary-wing landings, regardless of airframe:"

      No. Look at the Vietnam era film of Huey assault landings in a hot LZ. Those helos were down, unloaded, and gone in seconds. The MV-22, and to be fair, perhaps any very large helo, is going to be hanging, motionless, in the air at low altitude for an extended period, meaning minutes. That's an eternity in combat and a good way to die.

      That also leads to another aspect of the MV-22 (or any very large helo) as an assault craft and that is the troop capacity. The MV-22 is likely going to have a higher attrition rate due to its very poor combat landing performance. Thus, every destroyed MV-22 is also going to cost us the troops it carries. Since the MV-22 carries around twice as many troops as the Huey, we can expect over twice the troop loss rate.

      In fact, your discussion hinted that you would like to see an even bigger rotary assault aircraft with, presumably, even more troop capacity. Forgive and correct me if I've misinterpreted you on this. This would make the inevitable losses even more devastating. In combat, there is a LOT to be said for dispersal of risk even at the cost of inefficiency. We lost a lot of Hueys in assaults but the cost in troops per helo destroyed was less on a relative basis.

    4. Good point. The original air assault doctrine from the early 1960s called for Hueys to slow to five knots and troops would leap out. This idea of sitting down on the deck for five minutes while every files out the back ramp is nuts.

      Military contractors have quietly taken over editing Wikipedia entries as volunteers.

      Tiltrotor vertical lift performance is horrible because of its small twisted proprotors. A similar size helicopter can lift four times more with its long flat blades. The V-22 advertises 15,000 to 20,000 lbs of payload, although the max ever demonstrated is just 9800 lbs.

      Due to add-ons and because of weather factors and degraded engine performance, 6,000 lbs is considered the max safe vertical lift load, and pilots often use "interim power" at vertical take-off just in case. This is really emergency power where the pilot overstresses the engines to get a little more lift power. In the most recent V-22 crash it was attempting to land on an LPD with nearly 6000lbs, yet even that was too much to control as it sank fast and bounced off the flight deck into the sea.

      Those youtube videos are peacetime training exercises. Helos are limited to prevent stressing the rotors and other components, yet they can land much faster during wartime. V-22s can't because they are unstable and might roll over.

    5. I haven't seen V-22s use those Vietnam tactics, but that also doesn't prove that they can't. I haven't seen modern UH-1s or UH-60s do that either. I'm guessing a BIG reason why is that it's extremely dangerous and, wisely or unwisely, not justifiable under normal circumstances.

      I want it to be clear that I believe that ANY assault that requires such tactics is infeasible or inadvisable. IF we had to do one, yes I would use smaller airframes (i.e., a SB>1 as stated in my reply) for the reasons you stated.

      What I think you see in that video is the V-22 coming in very fast at very low altitude and then decelerating very rapidly at roughly constant AoA by putting the nacelles past vertical and increasing blade pitch. It is frequently stated that pure helicopters can't do this type of maneuver in SB>1 and S-97 videos (these aircraft can reverse pitch on the the prop to decelerate at constant AoA). The V-22 is far larger than a UH-60 and UH-1 and has much higher disc loading than the CH-53 or CH-47 (i.e., higher velocity downwash), so yes, I expect that it is touchier when settling into a hover. But assuming we are in a semi-permissive environment, do you want to spend a lot more time on the way into and out of the LZ (i.e., the last five or so miles) or more time in the LZ with the escorts circling overhead. And we aren't expecting indirect fire in the LZ, are we?! Different aircraft, different tactics.

      Since I don't foresee a huge role for aviation in the "assault," I think tiltrotors and larger airframes in general have a lot of advantages.

    6. "Since I don't foresee a huge role for aviation in the "assault," I think tiltrotors and larger airframes in general have a lot of advantages."

      That's fair. The post is not about the MV-22, in general, only about vertical assault landings. As a general transport it may be fine. I'm not a comparative helo expert to know which airframe is best for any particular general transport or cargo hauling.

      As an aside, I also note that the overwhelming anecdotal evidence suggests that the MV-22 specs are significantly overstated. Perhaps that's true of all aircraft but the MV-22 seems particularly overstated. Just an impression but all the MV-22 users (I get lots of emails from active duty personnel) tell me that the official specs are nowhere near able to be met in any realistic operating environment.

    7. @Anonymous

      Sources? At 9,800 pounds, we're talking close to double that is advertised for the CH-46 (5,000-6,000 pounds), the aircraft that the V-22 is "replacing." We're not losing anything versus the CH-46 by going to V-22 in terms of lift capacity and gaining a lot in other areas. You're not making a case for whether or not it's worth the trade-off.

      I get the sense that you are over-generalizing, over-simplifying, and de-contextualizing anecdotes to make a point about an aircraft you do not like, for whatever reason. It's not a zero sum game. There are pros and cons to every design decision. I don't understand what you are attempting to add to the discussion other than to solicit kudos from like-minded individuals.

      A word of advice, saying that X is "bad" because it doesn't do Y is not persuasive. What is your CONOPS? Why does the V-22 fit or not fit into that? Maybe then we can BEGIN to have a decent discussion.

      - Gripen

    8. The most ever proven in an OPEVAL is 9800lbs.

      Also, a quote:

      Rotorcraft expert and test pilot Nic Lappos explains:

      For a tilt rotor, the blades are purposely made with less chord than a helicopter, because the thinner blades are then operating at a higher angle of attack in a hover, and are more efficient. This means that they can save power in a hover by operating at a high Ct/sigma. The downside is that there is little margin left over for maneuvering at low speed. For helos, the blade chord is sized up to allow flight at high speed, so it is way oversized for a hover. Tilt rotors don't need the extra chord for high speed because they are on the wing by then, and the rotors are props!

      The V-22 has a hover Ct/sigma of 0.175, which means that it will stall at only about 1.2 to 1.3 g's in helo mode (.21/.175). A typical helo has a hover Ct/sigma of about 0.09, so it never gets close to stall at low speed.

      If an aircraft stalls, it rolls.

    9. That's an interesting data point. Thank you. That information, however, merely points to the advantages and disadvantages of optimizing the prop rotor design for power efficiency and wing-borne speed over hover performance. I'm not arguing that the V-22's hover performance is inferior to a pure-helicopter of similar size/weight. It almost certainly is inferior in that regard. The question is whether or not that's important given the role that a given airframe is designed and/or likely to fill.

      - Gripen
      - Gripen

  8. Regarding the latest version of the Huey, the UH-1Y Venom, Bell helicopter gives its carrying capacity of 8 passenger seats not a dozen

    You would have to go up a size to the latest Blackhawk to get the 11-12 troops. I think these would be the numbers of fully equipped troops for combat assault and for short hops with just to carry some passengers might be more.

    1. The UH-1 referred to in the post is the Vietnam era Huey and Wiki lists the troop capacity for the UH-1D of the era as 14.

    2. In Robert Mason's memoir, Chickenhawk, of his time in Vietnam as a Huey pilot, he describes the capacity of the helicopter as follows: "with the crew chief and gunner in the pockets, there was enough room for eight or ten troopers on the cargo deck."

      A more detailed passage:

      Our company of sixteen ships was the last flight on this extraction, so all the troopers pulled away from the tree lines and jumped on ships in groups of eight. Eight was the load for today. (How much the ship could carry depended on the density altitude, which varied with the temperature and humidity and altitude. The hotter or higher-and therefore thinner-the air was, the less we could carry. The limit was calculated daily.) But there was a fuck-up. After everybody had eight grunts on board, there were four men left over, running around being turned away. Leese saw this and immediately called for them to run back to us. Confused, they ran to the ships that were trying to tell them to come back to us. Everybody was nervous. The four grunts didn't want to be left behind. Reacher jumped out the back and waved. They finally got the message and came back. I didn't understand Leese's decision. We already had eight troopers on board. I'd been in a ship that had dragged the trees trying to get out of an LZ with eight on a day like today. Twelve was impossible. Finesse, luck, experience- none of that would get twelve grunts off the ground today.
      As soon as they squeezed inside, Leese brought in the power. I could feel the air pressure build up under the rotors as they struggled, pulling the overloaded ship slowly off the ground. Then he radioed Williams that he could make it. Leese stayed in a hover as the company took off. I glanced at the power gauge. It must have been broken. It indicated that we were using 105 percent of available power: As the company lumbered over the tree line, I heard them firing down into the jungle, then a few calls of hits, then we were alone. Leese nosed the stuffed Huey gently over, letting it accelerate across the ground to gain lift. He kept it just over the grass even as the trees approached. The gauges showed he was pulling maximum power, and we were running out of room. Then, somehow, he pulled in power beyond maximum. The ship groaned up and over the trees. I felt a tug when the skids hit treetops. The company had flown to the left at takeoff, but Leese turned right. I scanned the clearings and bushes below, looking for muzzle flashes or smoke, but I saw nothing. The ship climbed much slower than normal. It took us a long while to get up to the safety of altitude, but we got there.
      "How did you know this ship would be able to do that?" I asked.
      "Simple. This is Reacher's ship," Leese answered.
      "I don't understand."
      "This is the only ship in our company that can haul a load this big. Right, Reacher?"
      "That's right, sir, and more." Reacher's voice hissed in my earphones.
      Reacher had made certain fine, illegal adjustments of the turbine. I had never flown the ship before- Leese kept it to himself -so it was news to me. An army training film I saw would prove that it shouldn't have worked, but it did. The ship muscled through an important career for the next two months, saving a lot of lives, until I destroyed it.

    3. I worked in one of the last US ARMY units that still had UH1 and Cobras in the 90s. I asked an instructor if this was possible, having read the book, he said NO! But as a mechanic, when you did an engine test run and adjust the fuel mechanism, you had this little spacer that you had to adjust. I'm guessing they went all the way which probably gave a little fuel and power, not something I would recommend for long periods of time and better not let top management know.

      Loved working on the T53, it was a super strong engine that was a little bit on the overengineered side so there was some margin to push it for sure.

    4. Thanks for the comment Nico, the majority of what little I know about helicopter aviation comes from Mason's book, so it's always good to have more input!

  9. Actually ground fire probably shouldn't be the biggest concern. I was reading a report recent on future needs for vertical lift (I think it was from the Defense Science Board), and they stated that more aircraft and personnel were lost to accidents than enemy action.

    Randall Rapp

    1. 2000-06. The title is "Defense Science Board Task Force on Future Need for VTOL/STOL Aircraft" finished in Jan 2007. The Info is in the safety & survivability section on p. 84.

    2. Okay, now what point, if any, are you making?

    3. Just providing additional sources of information on the subject. Plus we have to worry about these sorts of losses in ALL types of operations not just combat ops, so focusing on them first might make sense, given their prevalence.

  10. The other side of the coin is that new technology and cost may make the original mission of amphibious assault a better option. at roughly $80 million a pop, how many new and improved AAV's or it's replacement could we field? Numbers don't just matter in terms of the amount of force brought to bear but also provides some safety in numbers. If 10% of a force of 20 Ospreys is shot down, you've lost over 150 million in planes, training, and troops and equipment and reduced the number of troops significantly.
    For the same amount of money you could field--at a 10 million each which is way more than they actually cost--160 AAV's carrying 3,200 troops vs 480 troops for the ospreys, plus they are landing in an armored vehicle that itself is armed.
    I quoted 10 million because we could also equip all these new AAV's with the tropy APS providing further protection against the very arms this post is about. And also upgrade the armament with some armed with 30mm or even the 105 of the Stryker AGS to provide more fire support. An Osprey can only field a .50 on the tail, and if upgraded a .50 gatling on the nose--roughly the same as the AAV has already.
    So even if the force lost 10%, you would have over 2000 hitting the beach in a vehicle that is well protected against many missiles, and small arms and can provide fire support as well.
    Unfortunately, ground combat IS about numbers whether it be lives, wealth, or more often both.
    Unfortunately 15 years of fighting against non-peers has the Corps leadership all but ignoring their main responsibility of taking the beach for being wannabe SEALs.

  11. The US Army has an entire division that specializes in Air Assault. That is called the 101AB division Screaming Eagles part of the 18th ABC that also includes the 82nd airborne division (paratroopers). Today they often broken up into brigades for rotational deployments for GWOT/OCO...The 101st AB div has aviation elements that include only helos like Chinook, Blackhawk, Apache attack and pathfinders etc.

    The USMC has air amphibious air assault capability for a MEU sized entry but you can be sure any hot LZs will be avoided no matter what...The Marine air capability includes H-53 and Cobra gunships along with their other helos in service. Again this is only to support a battalion of trigger pullers not brigades or a division. Since the 1960s the main USMMC troop hauler was the H-46 which was replaced by the V-22..The V-22 is no Chinook nor is the Chinook a V-22..The problem is the USMC needs an H-53 capability to be a crutch for their V-22 (due to all its limitations discussed) issues... That means the H-53K is now another new developmental aircraft like the V-22 and F-35B the USMC needs to acquire in number to move a single infantry battalion ashore... battalion ashore...Of course folks will pile on me and talk about F-18, Prowlers, C-130s the Marines can bring too but that is part of the Marine division or expeditionary sized force and need to be shore based, thus rarely called, except as a rotational replacement for those two Army divisions I mentioned above.

    That is the highest level the USMC can muster for a forcible entry unless a huge logistics movement is brought together as an entire Marine division, and that hasn't been done for many years. Air assault ala 101st AB? Forget it. Given the air vehicles the USMC demands as replacements for what they use to have, and in diametric opposition to what the US Army operatres today, one can see just how much "taxpayer treasure" is required to land one marine infantry battalion ashore... As a result, the USMC, which used to provide combat power efficiently, has become a combat niche unto itself... A forcible entry alone as an enabler? Kandahar sized effort again- maybe. Korean peninsula ala Inchon- Forget it. Who knows though? They have Marines in all key positions of government- LOL.


  12. Great discussion. For the history of the V-22 Development, and some insight as to why some design decisions were made, read the book The Dream Machine: The Untold History of the Notorious V-22 Osprey by Richard White.

    Put some interesting light on Goldwater, Lehman, Cheney, the USMC action officer and system engineering trade-offs.


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