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A400M Rollout

Higher speeds are possible with "compound aircraft", but these simply shift the lifting function to wings during forward flight, and the unloaded rotor is along for the ride somewhat like an autogyro.

If you look at pictures of the AH-56 Cheyenne you will notice the rather prominent wings, and the MI 24 Hind also had fairly large wings, which makes me think it's high forward speed was also a result of flying like a compound aircraft with an unloaded rotor.

As noted, escorting conventional transport helicopters like Chinooks, Griffons or Blackhawks might be a bit difficult with large mismatches in performance. If your escort aircraft are AH-56's, then your transports should be Fairey "Rotodynes".

Since helicopter rotors fulfill different functions than a propeller, simply translating what works in one environment does not necessarily work in another.
 
hauger said:
First, I know nothing of fling-wing aerodynamics,

No comment required.

hauger said:
but where my thoughts went with the whole rotor shape change was to allow faster rotor speeds to increase the max GWT of a machine.  I don't know if if works this way or not, if increased rotor speed allows for greater lift capability.

"Rotor shape change" would have little to do with rotor speeds.

Rotors are larger and have more mass than propellers - some amount of weight is necessary in order to preserve rotor RPM in the final stages of an autorotation aside from the natural mass - hence any additional speed generates more stress on the rotor system. Better balance is also required as things speed up.

There are other ways to influence lift: aerofoil shape, blade length and chord, blade pitch, number of blades etcetera.

Rotor blades are wings. Aside from the obvious fact that they rotate in order to generate lift rather than move along with all other parts of the airframe on a seized-wing aircraft, every point along the blade is moving through the air at a different speed, and corresponding points along other blades are often, but not always, moving through the air at different speeds. This is why one can see variations in pitch, or a twist, along a blade's length.

The Griffon's blades are described by Bell as "sculpted", as the aerofoil and chord vary along the length as well as the pitch. This is achievable as the blades are moulded synthetics rather than metal.

As the disc is tilted in order to split the more-or-less vertical lift vector of a hovering helicopter into vertical and horizontal (thrust) vectors, the airflow through the rotor changes significantly from something equivalent to a propeller's (straight through, but in our case downwards) into an angled and then largely sideways flow.

This is extremely simplified, of course. I know enough to operate the things; designing them is well outside of my lane.

Lift is increased by increasing the pitch of the blades collectively. This increases drag on the blades, and slows them down. Constant rotor RPM is maintained by working the engine(s) harder. At some point, the engine(s) run out of additional steam and any further increase in pitch causes rotor RPM to droop. Yes, more powerful engines could be installed, but there is always a trade-off - expense, weight, size, increased fuel consumption etcetera.

Higher ambient air temperature causes engines (and other dynamic components) to run significantly hotter, and temperature limits may be reached before power limits. It also makes the air less dense, degrading rotor performance.

Higher operating altitudes also degrade performance, and KAF is about 3000 feet above sea level.

hauger said:
I gotta go with the thought that if this was beneficial, someone would have incorporated it by now.

Yes. This is pretty much why I don't make design suggestions on Nuclear Reactors.ca.

hauger said:
I do disagree with the above quote though for in theater ops.

Based upon what experience? Add "operations" to your opening statement.

hauger said:
Helo speed can be highly beneficial depending on the employment of the asset.

Not much. Helicopters travel relatively short distances in tactical operations, and increasing speed will, at best, only shave a couple of minutes off of flight times over those distances. Most missions in our present theatre would be less than 50-60 km from KAF, which at 100 knots is less than twenty minutes.

While boosting theoretical max speeds may look nice on the shiney brochures, they are largely irrelevant when flying around with doors open and things hanging off of the sides or bottom, like guns, missiles, and slung loads.

You could do a Tim Allen and make a Leopard capable of doing 150 km/hr if you wanted to waste enough money and burn enough fuel, but why? Even if there was some small and occasional benefit to getting to places quicker by road, it's not moving any quicker cross-country without disrupting the internal organs of the crew and tactical movement is just not feasible.

hauger said:
As an air defense platform (aka: attack helo),

Attack hels are not "air defence platforms". They are attack hels. They make things on the ground blow up, burn, and bleed.

hauger said:
speed can be highly beneficial.

If it was, you'd still have to solve the other limiting factors previously mentioned, and even if that was achievable with current technology, it would most likely impose other limitations elsewhere. Like every single other military machine, helicopters have their strengths and weaknesses. They complement other vehicles and aircraft, which in turn complement them. Each machine has been optimized for its intended role.

hauger said:
A properly armed attack helo capable of speeds between 250 and 300 KIAS at various altitudes are very effective at providing low level harassment of tactical transport ops as well as providing the same ops with useful and beneficial attack coverage.

Are you refering to enemy or friendly ops, or both, and rotary- or seized-wing transport ops (the implication of your terminology would indicate the latter to me)?

This is not the role of AHs, and "harassment" of aircraft is not a useful activity compared to shooting them down.

Friendly transport aircraft would be escorted/protected by fighters, and enemy ones would be attacked by fighters and ground-based air defence systems. They exist for that purpose, among others.

AHs would be busy with the roles for which they are designed. To apply them to other jobs would require more of them anyway, so why not simply use something actually designed for the job?

Higher speeds add nothing to shooting ground targets, anymore than running around a target helps shooting at it with a rifle.

hauger said:
This is a capability Canada doesn't have,

CF18.

hauger said:
Apparently there's some issue with escort roles for our Griffon v. the Chinook due to speed.

As pointed out by Strike, no AH can keep up to a Chinook. None were ever designed for that role, as there was never any requirement until now. So the big fat helicopter goes a little slower, and it takes four or five minutes longer to get where it's going. In the overall scheme of things, that's not usually a big deal.

In less permissive environments, for which all battlefield helicopters have been designed, helicopters operate at low level around 100 knots or less as it's damned difficult to follow contours, dodge wires, trees, and cows, and navigate at any higher speed at an altitude that gives cover and concealment. Chinook, doctrinally, would fly from Corps areas to Division or Brigade areas and no further forward, so lower altitudes are not required and higher speeds are feasible. Its tactical limit was a minimum altitude of fifty feet. AH escort would have been extremely rare, just as truck convoys would not be provided with AFV escorts, as it was not necessary. There was no more tactical movement for Chinook than there was for HLVW.

Kiowa's tactical limits were "skids clear of ground and one-half rotor diameter from vertical obstacles". Speed was adjusted to match the necessary altitude. When I was using every little fold in the ground or shrubbery for concealment, I'd be just creeping along. At four feet, I'd be up to 40 to 60 knots tops. Griffon's (and Twin Huey's) minimum altitude is fifteen feet above obstacles and one-half rotor diameter, although we now have lower limits (four feet) at drastically reduced speeds (essentially taxiing) for certain missions. Griffon lacks the visibility and agility of Kiowa, hence lower is not a good idea. Speeds of 90 to 100 knots are certainly suitable for 15 to 50 feet above obstacles, which generally allows sufficient concealment for airmobile ops.

Faster just makes one go higher, which makes one more vulnerable.

Permissive environments allow other methods of operation (such as staying above effective small arms range), wherein, as we have seen, the characteristics of different helicopters may not be "ideal".

Any helicopter designed specifically for current ops may well be less than ideal for more traditional roles, and we could find ourselves back in that type of environment at any point in the future. We have bought a fair amount of ground equipment specifically for our current theatre that may be less than fully useful in the future also. Nothing does everything for everyone everywhere every time. That's life.
 
I really don't want to get into an "I'm smarter than you" contest, because on these boards they tend to devolve into harshness, and since I'm not a tactical god nor a high level big picture general, it's not worth the pokey-chest argument.

Having said that, here's some stuff I know.  CF-18's do not provide escort to low level tactical transport.  At best they provide top cover and can "leave the fight" (aka: come low) to provide some ground strike, but at the cost of loosing all their energy and needing to burn a tank of gas to get back high.  A better escort is the A-10.

What I do know is if a 130 meets an enemy chopper capable of 100 kts, it's not that big of a deal.  If same 130 meets a Hind, that's bad news for the 130.  It's hard to outrun a bad news helo if your speed delta is only 50 kts.  Of course the Hind isn't out looking for 130's, but if it comes across one, it has the smash to cause it some pain.

Of course, none of this is important if we fight wars with no airborne threat (Afghanistan).  Then fighters are free to come low all they want, and we don't have to worry about our trash haulers having to outrun unfriendly helicopters.
 
Hauger

WTF is your post about?
Military helos ARE capable of 100+ KIAS, easily.
F-18s DO CAS!! Quite well I might say so.
Any armed helo vs C-130 = disaster for Herky Bird.

Thanks for the lesson though

FAIL!
 
George Wallace said:
hauger

Do you have a Money Tree in your back yard?

Wait, what?

Jammer, I was responding to Loachman.  Yes, Mil. helo's can do 100kts +, but I'm pretty confident a 130 can DM around an armed Griffon (which isn't in the air to hunt transports to begin with).

In a normal air war, a fighters primary job is air superiority against enemy fighters.  In that sense, altitude = energy = advantage.  Giving up all that altitude to deal with a transport at 200 feet is not a target the fighter's there to deal with and is not something most fighters would be looking for, let alone go after since it means giving up so much energy (aka: altitude) to deal with.  There's a reason why maple & red flag rates of C-130's being "shot down" by fighters is very low.  While CF-18s do provide CAS, that is not their primary design.

My whole point behind mentioning the Hind (or the Apache) was just to point out that there is a benefit to having faster helicopters.  Granted, not in the traditional employment of them, but in a CAS role.  Canada can't and shouldn't afford them though simply because we have other, more pressing issues to deal with and the cost/benefit isn't there.

The original post though had to do with some basic aerodynamics of rotor design.  Innocently enough I was asking if a faster rotor speed equaled greater lift capabilities.  Honestly, I could care less, I don't fly helicopters.  Loachman liked to point out that rotors aren't props (no kidding, but I guess it's a common question and probably gets annoying after a while) and have different design functions.  I get that. 

Thanks for the lovely "FAIL" there Jammer.  I'm still pretty confident though that I have a bit of knowledge of what I'm talking about.  Oh, "Any armed helo vs C-130 = disaster for Herky Bird." isn't exactly true.  Maybe you should have a sit down with a TAL guy and discuss a bit.
 
Jammer said:
Military helos ARE capable of 100+ KIAS, easily.

Some not by much, and as I have said, practical speeds depend upon configuration, among other factors.

Jammer said:
Any armed helo vs C-130 = disaster for Herky Bird.

Hardly.
 
hauger,

Fighter-type aircraft can have a multitude of roles, even though they are called "fighters".  The name doesn't mean their only role is Air Superiority.  In fact, the F-18 was designed as a multi-role platform.  The F-15E doesn't even have and Air-to-Air role, yet, we call it a "fighter".  Sure some argue that it's a "strike fighter", but I think it's fair to say it's not a good "fighter" but does extremely well in the "strike" portion. 

Coming back to the F-18, it was designed (amongst other missions) to be loaded with bombs and A-A weapons, fight its way into a target area, bomb the shit out of that target then fight its way back out.  Air Interdiction type mission.  The design was proven effective during Gulf War I.  So, it can go deep into enemy territory, drop bombs and come back.  I'm sure if it can do that, it can do it, so to speak, close to or on the FEBA (in other words, it can do CAS).  It has been proven, again, in Afghanistan (not with ours, but other countries). In fact, CAS training happens here in Canada too.  And I can tell you that with the sensors it has, it can do a hell of a good job. 

So, a long story short, CAS has become a major point of interest, as far as I can understand, in the fighter force.

As far as C-130 vs Mi-24, unless the Hind has a shot forward of the 3/9 line of the Herc, I have a hard time seeing how it can generate enough closure to get a good shot from the stern.  But again, I'm not an expert in eighter helos or transport.
 
hauger said:
In a normal air war,

::)

a fighters primary job is air superiority against enemy fighters.

An over-generalization. Not all fighters have that job or even that capability.

In that sense, altitude = energy = advantage.

Generaly speaking, yes.

Giving up all that altitude to deal with a transport at 200 feet is not a target the fighter's there to deal with and is not something most fighters would be looking for, let alone go after since it means giving up so much energy (aka: altitude) to deal with.

Mission dependent.

  There's a reason why maple & red flag rates of C-130's being "shot down" by fighters is very low.

MF/RF are not real life. Close but.......

While CF-18s do provide CAS, that is not their primary design.

As a purposely designed multi-role fighter, the CF-18, i would say, has ground support as a primary design.

You should talk to commander 1 Cdn Air Div about where A-G sits on his priority list for the 18s tasks.

 
Not to say that Hinds and the like are going to chase around C-130s looking to shoot them down, but they can be equipped with AA missiles to make up for the loss of pursuit speed.

Hauger,
Why would a Griffon want to shoot down a transport A/C?
 
AARRGG. 

Okay, keep on topic here, does a faster rotor speed = greater lift capability?  It goes back to someone else's question of whether a blade change would allow the rotor to travel faster before the tips approach supersonic. Every other "argument" is nit picking and posturing.

Jammer, try and keep up here.  A griffon would not want to shoot down a 130, you, not I, suggested that it could easily do the job though.  Yep, AA missiles are bad news, but not that bad.  They're not much worse than MANPADS or SAMs, the main difference is the highly mobile Hind can stick with the 130 for a second shot a bit easier than a SAM site can.  Again though, I don't really care about the gritty details of what or why, the point was to illustrate one battlefield reason why having a helicopter with a bit more smash might be useful.

I'm not here to argue whether the CF-18 is good down low or not.  The 18 of course is being used extensively in A-G, it's a really good bomber for that and can hit targets quite well.
 
Jammer said:
Not to say that Hinds and the like are going to chase around C-130s looking to shoot them down, but they can be equipped with AA missiles to make up for the loss of pursuit speed.

Same things apply.  With 0 Aspect on the other airplane and opening range, the weapon engagement zone is reduced drasticaly.  It depends on the opening rate for sure and obviously the range, but I don't see how a Hind could get that close behind, unless the Hind is totally aware of the Herc, which is unlikely since he probably has other things to care about (ie: an other mission) and the Herc is totally unawared of the Hind.
 
Running a rotor at a higher RPM may not generate more lift in flight, indeed, it may generate enough unbalanced lift to damage the rotor head (generally not considered a good idea within the helicopter community).

More lift can be generated with clever aerodynamics (the oddly shaped ends of modern helicopter rotors is one example), or simple brute force approaches like going from 2 to 4 or even 5 bladed rotors, with the increasing complexity of the rotor head being part of the price you pay.

Since helicopters operate in different flight regimes than aircraft, they need different "tricks". Fast movers trade energy for speed, most helicopters operating in armed environments move in "rotor defilade" and need huge amounts of reserve power to "pop up" and fire on the target. From being a passenger on troop carrying Iroquois helicopters back in the day, lots of reserve power also makes for very exciting low level flying as well, such as rapid pull-ups and push-overs when crossing roads [in order to clear the telephone and utility lines]. (Strangely, Griffen pilots never seem to do those hair raising troop lifts anymore).

If a Hind driver wanted to use his high forward speed to destroy a C-130, his best bet would be to zoom over the airfield and rocket the transports on the ground.

Want to read more speculation about future aviation trends? Try here.
 
hauger said:

That sounds about how a few of us are feeling, alright.

hauger said:
Okay, keep on topic here,

Right. Anybody hear anything more about the A400M lately?

hauger said:
does a faster rotor speed = greater lift capability?

Sure, in theory. Then there's reality, as I addressed earlier:

Loachman said:
Rotors are larger and have more mass than propellers - some amount of weight is necessary in order to preserve rotor RPM in the final stages of an autorotation aside from the natural mass - hence any additional speed generates more stress on the rotor system. Better balance is also required as things speed up.

Thucydides understands this.

There are better ways to increase lift, as I outlined, but there is more than lift involved unless all that you want to do is hover over one spot for a full fuel load.

hauger said:
Every other "argument" is nit picking and posturing.

Like all of the other ones that you've thrown about?

hauger said:
Jammer, try and keep up here.

Hauger, try and keep up here. Read what you've written, sometimes more than once, and the responses received.

hauger said:
A griffon would not want to shoot down a 130, you, not I, suggested that it could easily do the job though.

hauger said:
A properly armed attack helo capable of speeds between 250 and 300 KIAS at various altitudes are very effective at providing low level harassment of tactical transport ops as well as providing the same ops with useful and beneficial attack coverage.

Granted, you did not state Griffon (It's a proper noun, so capitalized by the way), but you did make a suggestion regarding helicopters - optimized for certain roles for which they are suitable - and employment thereof in this other role, for which they are not suitable and which would take them away from their intended role for no valid reason. Again, this has been addressed.

hauger said:
the main difference is the highly mobile Hind can stick with the 130 for a second shot a bit easier than a SAM site can.

If there was only one SAM site anywhere on the ground.

Beyond its requirement to keep up with its own forces while they are on the move, why would a SAM site need to "stick with" any target? The SAM concept involves layering of weapons in depth across the whole battlefield. There are low altitude and short-range systems and long-range high-altitude systems in that mix. There are IR- and radar-guided systems. A target will move into the range of at least one system, and as it moves out of range of that one/those (presuming that it still survives), it has already moved into the range of at least one more. SAM systems just lie in wait while their intended targets come to them. That is far more effective and cost-effective than having some ill-suited helicopters flashing about just in case enemy transport aircraft bumble overhead, while sacrificing their designed operational capabilities. They'd be limited to short-range IR-guided systems only anyway. Fighters are far more effective at shooting down things in the air than helicopters.

hauger said:
First, I know nothing of fling-wing aerodynamics

That was the last worthwhile thing that you said. You've just been pissing into the wind since.
 
How far are the French (indeed Germans, I have the impression the Brits would be happy  to wave goodbye) willing to go to save the thang?

Murky Future for the A400M
Germany Remains Stubborn in Airbus Debate

http://www.spiegel.de/international/business/0,1518,670423,00.html#ref=nlint

Germany has dug in its heels in the face of Airbus demands for a further 5 billion euros to cover cost overruns in the development of the military transport plane A400M. A Defense Ministry official has said that Berlin will pay no more than is called for by the contract -- a position which could torpedo the project.

Even as Airbus warns that the fate of the military transport plane A400M hangs in the balance, Germany continues to reject demands from the company for more help with the massive cost overruns that have struck the project.

According to a report in the business daily Handelsblatt on Wednesday, the Defense Ministry in Berlin remains unwilling to provide Airbus with more than a further €650 million to cover inflation and surcharges as outlined in the purchase contract. Airbus, however, is calling on its European customers to cover 50 percent of the €11 billion in cost overruns.

"We will definitely not pay more than the €650 million in extra costs called for by the escalation clause in the contract," one unnamed Defense Ministry official told Handelsblatt. "It is nice that the airplane took its maiden flight in Seville," added Defense Ministry spokesman Holger Neumann, referring to last month's first test flight. "But that didn't fulfil a single condition of the agreement."

Plans to Scrap the Project

The Defense Ministry comments come a day after the Financial Times Deutschland reported that Airbus head Thomas Enders said over the Christmas holidays that he no longer believes the project will ever be successfully brought to fruition. Airbus has developed contingency plans to scrap the project should its European customers -- including Germany, France, Great Britain, Spain, Turkey, Belgium and Luxembourg -- not agree to renegotiate the contract. Talks are scheduled throughout January.

Airbus reinforced its warning on Wednesday, with a company spokesman telling Handelsblatt that "the project is impossible given the current contractual conditions. We need a financially sensible solution right away."..

Other European countries involved in the talks, including France and Great Britain [!?!], have shown a greater willingness to find a compromise than Germany. "I am confident because this is about the interests of European industry," said French Defense Minister Herve Morin on French television station BFM on Wednesday...

Mark
Ottawa
 
Sounds like Boeing has an opportunity to get in a final C-17 run if they can work fast and cheap...
 
Another headache for the A400M's export chances assuming the project carries on, the Kawaski C-X now XC-2 flew this week. 37 ton payload, faster and much cheaper, apparently about 85 million USD per unit. The Japanese claim that development costs are 3.8 billion USD which is about 10% of the cost of Airbus' headache to date. I realize Japan cannot export military equipment but Kawaski has said there will be a civvie version as well.

http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a49835293-e38b-4ebb-9a0b-c463eddc7b67&plckScript=blogScript&plckElementId=blogDest

It should be a nice aircraft for a reasonable price.

KJK :cdn:
 
Here is an URL about an impending showdown between EADS and the A400M customers:

http://www.spacemart.com/reports/Aerospace_chief_calls_for_clarity_on_new_transport_plane_999.html


Bearpaw
 
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