Using Canards vs. Tail for aircraft control in USA and other countries

[sferrin]

The USAF (not the USN) seems to plan their aircraft always enjoying long, smooth concrete runaways.

I agree, it is bazaar how little interest the American military seams to have in STOL. I sometimes think the US Marines, with there Harriers and F-35Bs, are the only ones with any idea of real world practicalities - having to operate land, sea and air together - and having to do this at the battle front ahead of all the other forces (don't all complain at once).

The AFTI program's ACTIVE F-15 with canards (F-18 tail surfaces) and 2D then 3D thrust vectoring is a case in point. It was advertised to address the damaged airfield scenario you suggest but the US seamed to carry out the programme grudgingly and then dropped it without a trace.

Also the rest of the world believes canards aid maneuverability and they did too - once. As I wrote in another thread the new F-35 is only supposed to have 'F-16 "like" maneuverability', a 30 year old design.

www.dtic.mil/dticasd/sbir/sbir022/n189c.ppt

Cheers, Woody

There was another vectoring thrust F-15 program years before that that was designed for the same thing (STOL) but the acronym escapes me at the moment. It only had 2-D vectoring thrust however.

 

[elmayerle]

Let us not forget the AVEN (Axisymmetric Vectoring Exhaust Nozzle) tests on a F-16.

 

[Woody]

Nice one Elmayerle. How many cool F-16 varients are there? Sounds like it could be the theme of a thread (if they didn't already appear in every other thread).

Let us not forget the AVEN (Axisymmetric Vectoring Exhaust Nozzle) tests on a F-16.

Here's the the 'AVEN' (Axisymmetric Vectoring Exhaust Nozzle) on the 'VISTA' (Variable stability In-flight Simulator Test Aircraft) under the 'MATV' (Multi-Axis Thrust-Vectoring) program in 1991; initially an Israeli sponsored program (VISTA) but then for the USAF's Wright Laboratory. (click link below to watch)

http://www.youtube.com/watch?v=DdeZiBITFfA

Its not a canard but still relevant as another maneuvering device that has apparently been ignored. And anyway it's a cool clip - almost biological.
Cheers, Woody

 

[Tam]

Here are some aspects of canards that I like to further mention.

1. Canards are preferred for post stall aka super maneuverbility. Due to an uninterrupted air stream, it is easier for them to regain control once the plane stalls. Likewise they are less likely to depart controllability at low speeds compared to tailed elevators.

2. Here is the nasty thing that goes with close coupled canard designs (not the Typhoon). They tend to generate wake that rolls over the main wing and runs through the fuselage, affecting lateral stability. The J-10 approaches this problem with a dihedral layout on the canards while the main wings are anhedral. From the forward view, the plane looks like an X biplane, only that the top rods are short and the lower rods are long. This would give some distance between the canard wake and prevent it from interfering with the main wing. One should note that adding a dihedral layout in the canards tends to increase stability along the rolling axis, and this is not optimal for maneuverbility, though allegedly the J-10 still manages to get a roll rate of 300 degrees a second.

However, as the wake flows over the fuselage, it affects the rudder, so this means you have to install a big rudder to compensate. We have seen so far, that canard deltas use relatively large rudders, which is not good for side aspect RCS. To help control the wake flowing over the fuselage, the J-10 also uses a thin strake that runs the full length of the spine, and this strake is even bigger on the two seater version in order to compensate for the turbulence added by the raised canopy.

In order to get a lower RCS, canted twin rudders may be the way, but the rudders have to be spaced wide and away from the main bore of the fuselage. This is similar to the purposedly leaked CG image of a twin engined canard delta being developed by Chengdu, as well the MiG 1.44.

In another concept, a Beijing startup proposed a model called the CY-1. The plane has a long strake along the side of the body that is used to smooth the canard generated turbulence.

3. Attempts to put active canards on existing airframes may not be as beneficial as it is with a purposedly design canard aircraft from scratch. Putting the canards and their associative mechanisms add forward weight to the aircraft, increasing stability at the pitch. Whatever gain you get from increasing lift at the front is partly offset by the increased weight in the front. In order to regain that balance, you may have to add a bit of ballast in the rear. Another reason is that it cuts up the fuselage to make room for the equipment and interrupts with the original stress lines of the plane. To compensate you need to beef up the remaining spars and that further adds weight. Sukhoi gave up the original plans to modify the IAF Su-30Ks to the MKI standard, and proposed instead a one to one replacement with brand new MKIs. If you want to imiprove maneuverbility on an existing airframe, going TVC would have been more efficient. It looks that Sukhoi has abandoned ideas adding canards to existing aircraft as future upgrades, and the latest Su-35 concept does not have canards either.

4. We didn't know a lot of stuff and behavior about active canard deltas until the X-31 research program was done. But by then, designs like the Typhoon, Rafale, and the Gripen were already cemented and wasn't able to take advantage of the research. I think we only just touched the surface when it comes to the potential of the configuration, and the planes we got now, are just first generation.

 

[Woody]

Now here' some high AoAs on an F-35 ;D

However, the simple fact is that canards don't have the high AOA capability tailed aircraft do unless they have thrust vectoring (see X-31).

(click below to watch)

http://www.youtube.com/watch?v=Hax3rhqGJcQ&NR

Who would have thought it? No canards, no tailplane, no thrust vectoring, but its not exactly what you'd call sustainable and doesn't go so well for the dark top one in the middle of the clip.

Cheers, Woody

(F-35 being the Danish J 35XD Draken(?) not the JSF)

 

[Woody]

4. We didn't know a lot of stuff and behavior about active canard deltas until the X-31 research program was done. But by then, designs like the Typhoon, Rafale, and the Gripen were already cemented and wasn't able to take advantage of the research. I think we only just touched the surface when it comes to the potential of the configuration, and the planes we got now, are just first generation.

Yeah - what has happened in aerodynamic research since the X-31 VECTOR programme ended in 2003 (?). I'd love to see some of those AVEN type nozzles on one of the Euro-canards. Anyone know of anything like that in the works? Probably not with the Eurofighter as apparently they can't even find a spare one to help develop the Meteor missile according to MBDA.

Cheers, Woody

 

[Trident]

A 3D thrust-vectoring nozzle for the Typhoon's EJ200 has already been tested on the ground, but things have gone quiet since.

 

[Matej]

Maybe it is because of the standard problem - money limit. Also every piece of every Eurofighter is now needed much than gold, so there is not enought time for some necessary tests.

 

[Woody]

Maybe it is because of the standard problem - money limit. Also every piece of every Eurofighter is now needed much than gold, so there is not enought time for some necessary tests.

"The Eurofighter partner companies have so far delivered 116 Tranche 1 Eurofighters to Germany, Italy, Spain and the UK, with the nations air forces having flown over 16,300h with the aircraft." Fight Global.com

I'd have thought the partner nations could find a couple of spare planes amongst all that lot, for the Metor or other development. It's not like they're all on the daily battle line fighting off invasions. Most efforts seam to be focused on deleting things like guns or trying to cancel the third tranche (Germany). It doesn't create a good impression for potential export buyers.

Matej, is that the AVEN nozzle or one for the EJ200?

Cheers, Woody

 

[Tam]

I'd love to see some of those AVEN type nozzles on one of the Euro-canards. Anyone know of anything like that in the works?

According to Jane's, China purchased upgraded AL-31FN with the Klimov nozze (as shown on the MIG-29OVT), these for the purposes of using them in the next variant of J-10s. Not to mention that China apparently is developing an AVEN nozzle (shown in Zhuhai airshows already) to be used in their indigenous engines, likely to end up in the J-10 as well.

 

[Sundog]

1. Canards are preferred for post stall aka super maneuverbility. Due to an uninterrupted air stream, it is easier for them to regain control once the plane stalls. Likewise they are less likely to depart controllability at low speeds compared to tailed elevators.

That is a patently false statement. The F-22 and YF-23 are proof of that; remember, both of those aircraft met the maneuverability specs and those specs were to make them better than the aircraft that would replace the Flanker. In fact, canards in and of themselves are more limited than a conventional tail at high alpha because they can't trim the aircraft at as high an alpha as a conventional tail can.

Also, I never said the canard aircraft isn't capable of high alpha flight. I said it can't trim the aircraft out at as high an alpha as a conventional tail can. Also, to correct another falsehood, the conventional tail is in clean air at high alpha, because it is below the wing, not behind it. Watch some of the high alpha test videos of the F-22 where the horizontal tails make it look like the F-22 is "duck walking" (because the tails look like webbed feet walking) and you'll see what I mean.

Also, that F-35 Draken video was cool, but that doesn't enter into this discussion for me, because that's a stability issue and a transient maneuver. I'm refering to sustained, controllable, high alpha flight.

However, has anyone seen any video of the YF-17 Cobra performing the Cobra maneuver at Paris and Farnborough in the mid 70's? I've read about it, but have never seen any video of it. I was just wondering if anyone knows of any existing video showing them performing this.

Back to canards, though. All of the European countries chose canards because they are lower cost than a standard aircraft. Canard aircraft are cheaper to build then aircraft with conventional tails because an aircraft with a conventional tail needs an empenage to support the tail, which means more structure and complexity and therefore more cost. Whereas a canard aircraft mounts the canards on a structure that already exists, the forward fuselage, although it does have to be strengthened over a standard forward fuselage to handle the loads. However, it's still a lighter solution than a conventional tail. Therefore, going with a canard configuration allows engineers to design a plane that is smaller and lighter, which means lower cost, then a conventional configuration for a given mission. However, smaller aircraft also have the problem of limited growth potential.

As was shown with the ATF program, an aircraft designed to dominate the aircraft that would replace the Flanker, the U.S. left no stone unturned in terms of configuration studies and the only major changes they made to keep costs down during the program, with regard to performance, was to omit the thrust reversers. Of all the design submissions, one had a canard, one was tailless, and the rest had conventional tails (I'm including butterfly tails as conventional due to their location). Of all those submissions, the canard design was placed last.

 

[Matej]

Matej, is that the AVEN nozzle or one for the EJ200?

Its for the EJ200. When you look at the left of the second picture, you can see some characteristics details of that engine.

 

[DWG]

I'd have thought the partner nations could find a couple of spare planes amongst all that lot, for the Metor or other development. It's not like they're all on the daily battle line fighting off invasions.

But five nations are trying to stand up development squadrons, OCUs and operational squadrons simultaneously, that uses a lot of airframes. And if the Saudi deal goes through then a big chunk of RAF delivery positions will be diverted to the RSAF, with RAF deliveries then later than planned.

Most efforts seam to be focused on deleting things like guns

The proposal wasn't to delete the gun, but not to buy the ammo and handling equipment, and even that only applied to the RAF and went away last year.

 

[Tam]

That is a patently false statement. The F-22 and YF-23 are proof of that; remember, both of those aircraft met the maneuverability specs and those specs were to make them better than the aircraft that would replace the Flanker. In fact, canards in and of themselves are more limited than a conventional tail at high alpha because they can't trim the aircraft at as high an alpha as a conventional tail can.

And how? The J-10 and the Gripen have both demonstrated being able to completely angle their canards almost vertically. Canard planes also never lost their ability to have controls in their tail, as a matter of fact, they still retain traditional tail surfaces. In a way, they're controlling from both sides of the fulcrum if the plane is like a lever.

I am talking about recovery from stall. It is easier to recover an active canard, because assuming you are not already plunging nose first, you can make sure you do by making the lift lose faster on the nose, causing the nose to fall down, and once speed picks up on the nose, the canards gets into the uninterrupted airstream.

Therefore, going with a canard configuration allows engineers to design a plane that is smaller and lighter, which means lower cost, then a conventional configuration for a given mission. However, smaller aircraft also have the problem of limited growth potential.

Somehow you got to tell that to the designers of the XB-70.

 

[elmayerle]

Therefore, going with a canard configuration allows engineers to design a plane that is smaller and lighter, which means lower cost, then a conventional configuration for a given mission. However, smaller aircraft also have the problem of limited growth potential.

Somehow you got to tell that to the designers of the XB-70.

Compared to some of the conventionally-tailed designs studied, the canard configuration of the XB-70 is "smaller and lighter", it's just on a much larger scale.

 

[Woody]

Wow, this is turning into a bit of a bun fight. Come on, someone else help Sundog out for the pro-convention tail lobby. I myself like canards but I am genuinely curious as the ATF and JSF programmes wouldn't have abandoned canards for nothing.

I said it can't trim the aircraft out at as high an alpha as a conventional tail can.

Sundog: This argument has the ring of truth about it but, 1. isn't super high AoA only for pointing and shooting (useful if the missile/gun can handle it)? and 2. a more stable plane (not that I'm saying the F-22 is stable) is always going to be easier to trim but I thought too much stability was something we're trying to avoid?

Therefore, going with a canard configuration allows engineers to design a plane that is smaller and lighter, which means lower cost, then a conventional configuration for a given mission. However, smaller aircraft also have the problem of limited growth potential.

This: canards = smaller and cheaper argument seams specious; doesn't that equate to: canards = bigger for the same money, in the case of the US? And if money saving is not a problem for US why did the F-35 end up with no thrust vectoring (in flight)? I disagree that an A-10, F-16 and Harrier replacements doesn't need maneuverability. Have you ever flown them in simulation against SAM/AAA defenses? (My own favourite is the Hornet with 11 pylons worth of Mavricks.)

I only meant the Drakken video as a bit of a laugh.

Of all the (ATF) design submissions, one had a canard, one was tailless, and the rest had conventional tails

Do you have a definitive list/picture of the final ATF submissions? I can find hundreds of studies here on the site but I'm not clear on what was actually proposed. It seams Grumman, Boeing, Rockwell, McDonald and even Lockheed considered canards at some stage. The best I can do is Elider's models (below) but I don't know which is which.

But five nations are trying to stand up development squadrons, OCUs and operational squadrons simultaneously, that uses a lot of airframes. And if the Saudi deal goes through then a big chunk of RAF delivery positions will be diverted to the RSAF, with RAF deliveries then later than planned.
The proposal wasn't to delete the gun, but not to buy the ammo and handling equipment, and even that only applied to the RAF and went away last year.

DWG: 116 is still a lot of planes. And what's the urgency now to get operational? Europe faced Mig-29s and Flankers for years with no adequate equivalent. This is at the expense of staying competitive in the future or even being able to field a decent missile (Meteor).

As to the gun, I clearly remember reading in flight that the RAF wanted the gun deleted apparently to save fatigue on the airframes during firing; I'm glad if this has gone away.

According to Jane's, China purchased upgraded AL-31FN with the Klimov nozze (as shown on the MIG-29OVT), these for the purposes of using them in the next variant of J-10s. Not to mention that China apparently is developing an AVEN nozzle (shown in Zhuhai airshows already) to be used in their indigenous engines, likely to end up in the J-10 as well.

TAM: I can't wait to see Youtube clips of a thrust vectoring J-10 (as long as I'm still safe here in Japan).

You make an interesting point in that canards have tail surfaces in the form of their elevons, but doesn't that reverse the loading at the rear of the wing, removing some of it's lift/turning power? A Sukhoi like triplane would seam a good compromise if it didn't add the weight and complexity of both canards and a tail. I would suggest only 2 sets of wings but making the canard and main wing more similar in size (I've only seen this on some HiMAT drawings) and making the main wing more tail-like with variable incidence perhaps, at least in the outer sections. Any thoughts?

Its for the EJ200. When you look at the left of the second picture, you can see some characteristics details of that engine.

Matej: Did it ever fly and do you know what became of the programme?

A parting thought: some say stealth will be made obsolete soon but what if the reverse is true? Many nations are developing stealth aircraft (China will probably be the next to field) and soon they will become ubiquitous. And then BVR combat will truly be dead! We will have a new age where once again speed, maneuverability and guns are king.

Cheers, Woody

 

[Firefly 2]

I know I'm a bit of a nitpicker, woody, but... If stealth(y) airplanes become common wit both Low IR and Low RCS, then there will be little to lock on for most AAM's.
Does your view imply a return to pre BVR dogfights?

 

[Woody]

I know I'm a bit of a nitpicker, woody, but... If stealth(y) airplanes become common wit both Low IR and Low RCS, then there will be little to lock on for most AAM's.
Does your view imply a return to pre BVR dogfights?

That's quite alright Firefly, but if you re-read my comment I did say guns.

And then BVR combat will truly be dead! We will have a new age where once again speed, maneuverability and guns are king.

I just meant it as a laugh but historically its always been folly to develop weapons without considering the enermy will adopt them too.Thanks for giving me an opertunity to quote myself.
Cheers, Woody

 

[DWG]

116 is still a lot of planes.

Not when it's split across four, soon to be five nations. Tactics development squadron: 6 aircraft. OCU: 6-12 aircraft. Operational squadron: 12 aircraft. Total=24-30 aircraft. Times 4 nations = 96-120 aircraft required to stand up one operational squadron for each of the partner nations (and the RAF is converting its second operational squadron while the Luftwaffe is converting its second JG). That's without any allowance for aircraft in upgrade cycles or attrition reserve. Add in an Austrian squadron piggybacked on German training and you need 130 plus.

And what's the urgency now to get operational? Europe faced Mig-29s and Flankers for years with no adequate equivalent.

The world's not as stable as it used to be during the Cold War. Reports say Typhoon is likely to debut over Afghanistan next year.

This is at the expense of staying competitive in the future or even being able to field a decent missile (Meteor).

AIM-120C5 isn't decent? In any case, why chop a limited asset to preliminary trials when you can use an established in-service type such as Gripen? An actual Typhoon is only needed when the weapon is ready to be integrated/qualified on the aircraft. Meteor is years short of being ready for that, but things like Enhanced Paveway II and GBU-16 are, and Typhoons are made available for those trials. Weapon integration for military aircraft is something that tends to continue throughout the lifetime of the aircraft, rather than something that is done all at once at the start. For that matter Typhoon has just flown a series of flights with a Meteor Environmental Data Gathering Missile to collect data on how the missile interacts with the inflight environment on the Typhoon.

 

[Tam]

The things is, current delta canards are disadvantaged in low speed high AoA maneuvers due to their main wing, not because of the canards. These planes are still flying with low aspect, acute sweep wings that are from ideal for low speed high AoA maneuvers, as they have a tendency to bleed speed fast and produce too much drag if the AoA gets too aggressive.

The canarded Flankers avoid that problem because they still have a main wing with only a moderate sweep.

This: canards = smaller and cheaper argument seams specious; doesn't that equate to: canards = bigger for the same money, in the case of the US? And if money saving is not a problem for US why did the F-35 end up with no thrust vectoring (in flight)? I disagree that an A-10, F-16 and Harrier replacements doesn't need maneuverability. Have you ever flown them in simulation against SAM/AAA defenses? (My own favourite is the Hornet with 11 pylons worth of Mavricks.)

I don't really see how canard deltas end up being smaller, using practical examples.

The J-10 for instance, isn't smaller than the F-16 nor its sibling the JF-17.

The Gripen for that matter, isn't smaller than the JF-17 or the F-CK-1, despite sharing the same weight range.

For that matter, there is no reason for them to be cheaper either.

You make an interesting point in that canards have tail surfaces in the form of their elevons, but doesn't that reverse the loading at the rear of the wing, removing some of it's lift/turning power?

Didn't stop the Draken from making those maneuvers, doesn't it?

At high AoA, the main wings aren't not exactly making lift from those angles, they're braking the plane instead. You are instead using the tail elevators as lifting surfaces because their negative angles would become a lifting angle once a certain AoA has passed. If the canards can angle far enough, and pictures show the J-10, Gripen and the Typhoon can most certainly can, they can produce a similar result. Having larger control surfaces on the main wings would help.

A Sukhoi like triplane would seam a good compromise if it didn't add the weight and complexity of both canards and a tail. I would suggest only 2 sets of wings but making the canard and main wing more similar in size (I've only seen this on some HiMAT drawings) and making the main wing more tail-like with variable incidence perhaps, at least in the outer sections. Any thoughts?

The problem of a triplane is that they produce a lot of drag. In the case of the Su, it turns out that the benefits of the canard vs. the former LERX didn't make that much of a difference.

What you are proposing is quite interesting. At the Sinodefence forum, planeman have drawn up something similar except he joined the wing tips together between the canards and the main wing, which happens to be forward swept, creating a joined wing biplane. You should check the designs out.

http://www.sinodefenceforum.com/showthread.php?t=2844&page=5

 

[Woody]

Thanks DWG,

This isn't really about canards but the Eurofighter is 'a' canard...

116 is still a lot of planes.

Not when it's split across four, soon to be five nations.

It certainly wasn't my idea to give the RAF's next batch to the Saudis (or to sell them at all under the circumstances) but aren't all the partners on the same side? Do we really need that level of duplication at this stage? Its seams ludicrous to me that Eurofighter doesn't have the permanent use of a couple of development aircraft for just these sort of things (same management as the A380?). The F-15 programme used early aircraft for the ACTIVE programme and to develop the Strike Eagle; Eurofighter should be doing the same at least to develop potential improvements to stealth (the Typhoon's biggest problem).

AIM-120C5 isn't decent?

The AMRAAM is supposed to good missile but its only as good as everyone else's and possibly not as good as the Russian R-77/AA-12. The Meteor is potentially a great missile and a generation ahead. One of the reasons why it is so far off is that MBDA can't (or couldn't) get a Typhoon to test it on. I hope this has changed.

The world's not as stable as it used to be during the Cold War. Reports say Typhoon is likely to debut over Afghanistan next year.

Are you sure the Taliban will really care whether they are being bombed by Typhoons or Tornadoes (a perfect roll for an aging type?), and I thought that the typhoon, embarrassingly, wasn't to get air to ground ability (or designator pods) until tranche 3?

Day to day expediency is all very well but, do we want to go through 20 years of technical and political struggle just to stop development dead in its tracks at the earliest opportunity? We will loose all the knowledge base, technicians etc. and start falling behind again and when we do need an improved plane well have to start from scratch. From an export point of view; if I was thinking of buying a plane/car/software I wouldn't want one I new was the last of the type (first delivered 4 years ago) with no more upgrades in the pipeline. Would you?

Cheers, Woody

 

[Woody]

Thanks TAM

The things is, current delta canards are disadvantaged in low speed high AoA maneuvers due to their main wing, not because of the canards. These planes are still flying with low aspect, acute sweep wings that are (far) from ideal for low speed high AoA maneuvers, as they have a tendency to bleed speed fast and produce too much drag if the AoA gets too aggressive.

That's first time I've heard anyone say canards are bad at low speeds or did you just mean at presenting a high AoA posture? I agree with just about everything else you say, but my main point was that high AoA is not important if you can achieve a good rate of turn without it.

I don't really see how canard deltas end up being smaller.

Agreed, look at the MIG 1.44 (but if that means you can make it smaller and cheaper then all the better).

At high AoA, the main wings aren't not exactly making lift from those angles, they're braking the plane instead.

Couldn't have put it better myself.

At the Sinodefence forum, planeman have drawn up something similar except he joined the wing tips together between the canards and the main wing, which happens to be forward swept, creating a joined wing biplane. You should check the designs out.

http://www.sinodefenceforum.com/showthread.php?t=2844&page=5

I think the previous page is even more interesting especially with the contributions from 'Deino'. Is that our 'He was my North, my South' Deino? Fascinating to see what a good carrier plane the Rafael (a canard) is if I read his chart right.

http://www.sinodefenceforum.com/showthread.php?t=2844&page=4

Nice concept there, the fuselage would perhaps form a lifting body, but the canards and main wings seam to be above and below each other, not close-coupled, more of a box wing. I thought that would be a missed opportunity for extra turning power. And the upper forward, all moving wing is very straight so would have to be very thin. I would like to see a front on view and see more detail where the gear and hard points are supposed to be. Also I would like to know where the C of G is to work out the relative wing loading to imagine how it might maneuver.

But to re-iterate: Super high angles of attack are acts of desperation. They kill a plane's energy and without thrust vectoring probably don't even help you turn. Unless your aircraft is basically stationary (which is where you'll soon be) you'd be lucky to hit a barn door with either missile or gun whilst performing such maneuvers.

Thanks TAM. I'm off to read your stuff on the J-10 in the General Aerospace section which is where this should probably be.

http://www.secretprojects.co.uk/forum/index.php/topic,1402.0.html

Cheers, Woody

 

[Firefly 2]

I know I'm a bit of a nitpicker, woody, but... If stealth(y) airplanes become common wit both Low IR and Low RCS, then there will be little to lock on for most AAM's.
Does your view imply a return to pre BVR dogfights?

That's quite alright Firefly, but if you re-read my comment I did say guns.

And then BVR combat will truly be dead! We will have a new age where once again speed, maneuverability and guns are king.

I just meant it as a laugh but historically its always been folly to develop weapons without considering the enermy will adopt them too.Thanks for giving me an opertunity to quote myself.
Cheers, Woody

You are welcome

 

[DWG]

It certainly wasn't my idea to give the RAF's next batch to the Saudis (or to sell them at all under the circumstances)

The whole point of building an aircraft is to sell it. The more you sell the less they cost the most you sell.

>> Do we really need that level of duplication at this stage? <<

It's a national choice, presumably the Tri-National Tornado Training Establishment wasn't considered successful enough to be worth replicating (and in fact the TTTE stood down a few years ago).

>>Its seams ludicrous to me that Eurofighter doesn't have the permanent use of a couple of development aircraft for just these sort of things <<

They do, 7 DAs, 5 IPAs -- though most of the DAs are now retired, flying out of the national test centres. I think you are seriously underestimating the amount of development flying involved in the programme (or any flight test programme) -- take a look at http://www.eurofighter.com/Evolution/DA/ which goes through what each aircraft has been doing. And remember that for every test point the aircraft flies a team of people will have spent time designing it, ensuring it's a reasonable next step, the test pilot will have spent time rehearsing it in the simulators and after it has been flown they'll spend time reviewing the results and the telemetry in minute detail to verify that it did exactly what they expected. Flight testing done properly takes a very considerable amount of time and effort.

One of the reasons why it is so far off is that MBDA can't (or couldn't) get a Typhoon to test it on. I hope this has changed.

They don't need a Typhoon at this point in the programme, just a hack to get it into the air.

I thought that the typhoon, embarrassingly, wasn't to get air to ground ability (or designator pods) until tranche 3?

You've been listening to the headlines, not the actual facts (non-specialist reporting of aviation occasionally reaches the dizzy heights of only being dire, as opposed to abysmally dire). All RAF Tranche 1 Typhoon F.2s will have the austere A-G capability (Litening III LDP, Enhanced Paveway II), extended A-G capability comes in Tranche 2.

Day to day expediency is all very well but, do we want to go through 20 years of technical and political struggle just to stop development dead in its tracks at the earliest opportunity?

Who said anything about stopping development? There's Tranche 2 to be completed, Tranche 3 to be started, additional weapons to integrate and qualify, CAESAR to test fly and so on.

 

[Tam]

That's first time I've heard anyone say canards are bad at low speeds or did you just mean at presenting a high AoA posture? I agree with just about everything else you say, but my main point was that high AoA is not important if you can achieve a good rate of turn without it.

I probably did not phrase it right. Canards are not bad for low speeds, actually, they're quite good at it (Wright Brothers aircraft). What I was saying is that the main wing, acutely sweeped deltas, are not good at low speeds as well as in presenting a -low speed- AoA posture (not a problem at high speed however). We really should not be blaming the canards for the overall plane behavior when there is still the main wing to contend with. This is however an easy compromise for better high speed performance because canard-deltas do tend to excel in mid to high speed maneuvers, which is what I think really counts these days.

 

[Woody]

Thanks TAM, your stuff on the J-10 was amazing (if a little optimistic?). Why do you think all the current canards use deltas. Would straighter or FSW be a better solution? And do you have any thoughts on the relevancy of high AoAs in combat (since everyone, even Eurofighter, goes on about it).

Thanks DWG for your reply. It sounds like you are much closer to the subject than me. Sorry if I sound abrupt but if I, as an aeroplane nut, have these impressions maybe its an indication what less interested people are thinking.

The whole point of building an aircraft is to sell it. The more you sell the less they cost the most you sell.

I'd really rather Eurofighter stuck to selling such sophisticated and lethal things as Typhoons to customers like the Norwegians or Canadians with good human rights records (but that's politics not aerospace).

It's a national choice, presumably the Tri-National Tornado Training Establishment wasn't considered successful enough to be worth replicating (and in fact the TTTE stood down a few years ago).

I still think its sad they can't get it together.

They do, 7 DAs, 5 IPAs -- though most of the DAs are now retired, flying out of the national test centres. I think you are seriously underestimating the amount of development flying involved in the programme (or any flight test programme) -- take a look at http://www.eurofighter.com/Evolution/DA/ which goes through what each aircraft has been doing.

Thanks for the link. Its nice to know they had 7 development aircraft but you say most of them are now retired? There must have been a lot going on but the advertised schedule doesn't give much of an impression of urgency.

Example: "March 1994: The first Eurofighter, DA1 makes its first flight from Manching, Germany. August 1997: DA1 flies from Manching, Germany to Warton, England to commence a two-week co-operation flight trial." That's a 3 year gap (and there's a lot more like that).

Another example: "June 1998: DA3 successfully jettisons an external fuel tank (1000 ltr.). February 1999: DA3 flies for the first time with wet fuel tanks (1500 ltr) testing the functionality of the fuel system." It took them 8 months to put fuel in them?

And my favourite: (DA3) "March 2004 First in-flight Gun firing achieved." Does this mean 25 years into the programme and 1 year after deliveries start only then do they fire the gun in flight? (if not its quite misleading)

They don't need a Typhoon at this point in the programme, just a hack to get it (Meteor) into the air.

Your probably right but don't they need a Typhoon for radar and systems matching or are they expected to do that only after everything else is completed? I'm glad you say they have done some testing.

All RAF Tranche 1 Typhoon F.2s will have the austere A-G capability (Litening III LDP, Enhanced Paveway II), extended A-G capability comes in Tranche 2.

I thought there was a tender out right now for targeting pod for the Typhoon? I you're right I'll never trust Flight again.

Who said anything about stopping development? There's Tranche 2 to be completed, Tranche 3 to be started, additional weapons to integrate and qualify, CAESAR to test fly and so on.

Your idea and my idea of development seam a little different. I know the Typhoon is a fantastic aircraft and more complex than I can ever imagine but please excuse my ignorance if, to me (a layman), what you describe sounds more like getting the product finished 4 years after deliveries started. And that ongoing, unending situation has replaced what I would consider development.

Its not just the Typhoon, everything seams to take longer these days. The programme has been going for almost 30 years since first envisaged, that's nearly the same time as from the end of WW 1 to breaking the sound barrier or half the time since the end of WW 2. I know things are different now but in the fifties we went through 3 generations of fighters in a decade! Technology and modern attitudes don't seam to be helping.

So the Typhoon is an amazing aircraft (one of my favourites) but if we want to sell it in competition with the F-35 we had better start developing its stealth and thrust vectoring (and the Meteor) by early next decade or we can kiss any export hopes goodbye.

DWG,thank you for your indulgence, Woody

 

[Sundog]

I'm done with this thread. Some day when you actually sit down and design aircraft and perform trade studies, you'll know what I'm talking about. You have to design to the mission, not the weight. In all the design studies I've read for a given mission for a aircraft the canard was always the cheaper solution. Comparing the costs of the aircraft the way you did was inherently silly, since each of the countries developing them had different standards of development and differing technological bases to fall back upon. You're assuming developing CCV FCS's were the same cost for country X as they were for country y. There is just far too much error in most of the anlaysis I read here.

Also, with regard to the Gripen, the favored design was the model 2107, which had a conventional tail, but was rejected because of the dorsal inlet.

Also a canard design is not more or less unstable than a conventionally tailed design. It's simply a matter of how you design the aircraft. At low airspeeds, the tail on the conventional layout produces lift just like a canard if both aircraft are inherently unstable in pitch.

 

[lantinian]

I would stick with Sundog on the canard / tail matter. Canards the choice for the best boys in the block!

Lets look at the MFI program. All 3 original proposals featured canards. Yakovlev, MiG and Suchoi. And did they entered service. Now look at what the PAKFA likely designs look like. The more time passes the more we have an ATF looking airplane drawings, with tails only and traditional delta wings and a Russian star on it. ;D

Canards looked cool on all the original ASTOVL program in 1993 but by the time they were to chose the JSF only Boeing had a design without horizontal tail. However even they adopted it for the production JSF proposal. And F-35 is a very serious all around fighter.

Same with the ATF. The earlier you get in the program the more canard designs you had. However by the time they got to the winning design its was a massive aft tail victory.

IMHO if the 2 Biggest US fighter design programs in recent history have so profoundly rolled out the canards that early in the design process then canards are not the overall best option for such class of aircrafts. PERIOD :-X

regards to all,
lantinian

 

[Tam]

Thanks TAM, your stuff on the J-10 was amazing (if a little optimistic?). Why do you think all the current canards use deltas. Would straighter or FSW be a better solution? And do you have any thoughts on the relevancy of high AoAs in combat (since everyone, even Eurofighter, goes on about it).

Planes like the F-16 and the F-15 can be considered "clipped" deltas. Tailed deltas, the most classic of which is the MiG-21, also has their advantages over a pure tailless layout.

Current deltas should use canards or tails (like the MiG-21) because being tailless sucks. You have the same control surfaces doing double duty, you are exerting negative force from the main wing of the plane, not from the elevator. The main wing is supposed to be for lift, not downward force. You are exerting this negative force closer to the fulcrum moment of the aircraft, which means it would require greater authority which means more negative lift, and this means a more aggressive deflection of the elevons, which means more drag. None of this is beneficial. Whereas a much less aggressive trim would have sufficed for a tailed or canarded aircraft. In theory, the farther you can move the control surfaces from the fulcrum of the aircraft, the better, whether its forward or backward. In addition elevons are still part of a wing, not all independent moving surfaces. From the begining, Mikoyan had the right idea by sweeping the elevator as far back as he can.

High AoA maneuvers is as you mentioned, more of a desperation maneuver, and no matter what the plane, you lose energy which puts you in a highly compromised position. You definitely don't want that if you're being tailed by a missile. Aside from the hollywood/anime imagination of dodging missiles with missiles whizzing by underneath the aircraft in last moment maneuvers, the best way to evade a missile is distance and speed. If you can stay ahead of it long enough, the missile will run out of steam.

Stuff like cobras are airshow marketing stunts, very little relevance. But vitally important if you want to make an impression in front of goverment officials that will buy your aircraft.

At low airspeeds, the tail on the conventional layout produces lift just like a canard if both aircraft are inherently unstable in pitch.

Only when the aircraft is flying straight. During a turn, you need the lift to negotiate around a turn quickly. The elevators would not be producing lift at all, rather the opposite, so you have both a positive and a negative acting at the same time. A canard delta woud be both on the positive.

The bad thing about canards is the wake that goes behind them and all their turbulent effects. The FCS is not gong to be cheaper on such an aircraft because of this considerations, nor is the testing and design of the aircraft, since the effects are not fully understood and will change from plane to plane. I am surprised no one ever brings this up.

For example, with the Rafale, you see a situation when you have both LERX and canard. This makes you wonder how the plane generates its vortices and canard wake, and how they would interact. Even with the four canard deltas in service---Gripen, Typhoon, Rafale, J-10---there is quite a difference in their aerodynamics that deserve seperate discussion and analysis for each.

 

[Woody]

Thanks guys, more food for thought.

I'm done with this thread. Some day when you actually sit down and design aircraft and perform trade studies, you'll know what I'm talking about.

Sundog please don't go off and sulk. I do believe you have insights I do not possess. Your explanation about trim power was enlightening but I really don't get the canards = small and cheap and why therefore they are unsuitable for a larger plane. I don't mean I disagree, I don't understand it.

Lets look at the MFI program. All 3 original proposals featured canards. Yakovlev, MiG and Suchoi. And did they entered service. Now look at what the PAKFA likely designs look like. The more time passes the more we have an ATF looking airplane drawings, with tails only and traditional delta wings and a Russian star on it. ;D

Likewise Lantinian, saying the Americans and now the Russians chose conventional horizontal tails is self evident. I do not think they are idiots. What I would like to know is the engineering argument why. Do you have any images of these Russian planes, I'm very interested. All I've seen is the rough 3 view below or Josef Gatial's renderings of the same.

The bad thing about canards is the wake that goes behind them and all their turbulent effects.

And Tam, glad we agree about AoA being over-rated. I don't understand why canard wake is so bad but Su-27 type LEX vortexes are good. And I agree that tailless deltas seam a bad idea especially for carrier landings (because of the massive pitch up required to counter the negative elevon lift) but the Mirage 2000 is cool maneuverable plane (because of clever leading edge slats and inherent instability(?)). I can't explain why but placing the control surfaces too far from the centre of rotation would seam to make a plane too stable or is this an illusion (like a long wheelbase on a car)?

And DWG, apologies once again for being an arrogant little punk.

Cheers, Woody

 

[lantinian]

To Ogami musashi.
It is not a secret that from purely aerodynamic/weight point of view as Sundog explained, the canards ARE a better option for controlling the aircraft's pitch in level flight.
I think the high angle of attack is definitely an area of more dispute between the canard and the aft tail. Aerodynamically the tails may seam like in a more unfavorable position.

Yes i know tails are below the wings but Air masses flow goes downward especially at high AOA's.

True’s and make sence however if there is no wing lift (the wing as stalled) what is the reason behind the mass of flow going downwards. It may be quite the opposite, with the wing stalled and the aircraft lost its lift, the airplanes might actually be loosing altitude, in which case the air stream could be going up.

Lets assume a plane is flying at 90 degrees AoA. Which will bring the nose down better? The canard can only do that with negative lift against the wing huge positive lift. I'd say its impossible for the canard. What happens if the canards is locked in its level position? It will generate even more positive turning moment trough its face drag.
Can the tail bring the wing back from this position? Certainly yes. In a typical cobra maneuver the tail is locked in its level position and thought its sheer size and drag acts to tunr the clean nose down.

This shows me that that and tail controlled aircraft will always be able to recover from extreme alfas while a canards controlled one might not.

While the canard has a definite positive pitch advantage the aft tail make up with a more potent negative pitch authority trough simple physics laws. And negative pitch actually is the High AoA enabler. The positive pitch only gets you there.

for the F-22 it is unclear if the TVC is necessary for the 60° AOA

I personally am very familiar with the F-22 TVC philosophy and fully agree with it. Without the TVC the F-22 can do anything is can with it. With TVC the F-22 does the same things faster (turns) or slower (tail slides). In short. the F-22 TVC is not used to expand its flight envelope.

But lets look at that else does the canards bring to the table.
Can it be used for Roll? Yes but it two engine fighters equal or closer to the roling axes than it the tail. Hence less leverage. (blind obvious)Also, even it we all agree then in positive pitch it is better (I do) in roll you have only one of the canards doung the positive and the other the negative, and in negative pitch the tail rules.

What else. Yaw? Can canards help in yaw. Not really. Can they be made to? No because, sizing the canards to act both as yaw, roll and pitch would be...close to impossible, given pilot view requirements, affect on wing, weight impact on the forwards fuselage.
Can tails help in Yaw? Conventional ones NO. Can they be modified? YES, and the YF-23 is te perfect example of that. More on that later

So to sumarise IMHO:

Level Flight:
positive pitch : canard > tail
negative pitch: canard < tail

Hight AoA Light:
positive pitch: canard >> tail
negative pitch: cannard <<< tail

Roll: canard << tail

Yaw: canard << tail

Stealth: canard << V -tail
Multifunctioonality: canards << tail
Size limits: canard < tail

Also the pitch advantage of the cannards is negated due to the over G concerns

I assumed and Eurofighter type of Cannard and MDD JSF type of tail.

Regards,
lantinian

 

[lantinian]

saying the Americans and now the Russians chose conventional horizontal tails is self evident. I do not think they are idiots. What I would like to know is the engineering argument why.

Well, you accept the fact......but you do not accept the reasoning provided by Sundog for instance. Judging from your post so far in this treat I am not even sure that you are trying to find out the truth even when it is in front of you. You have an established opinion and a bias towards to canards. Well do for something. You argue their merits, yet you seek confirmation on the contrary facts which are self evident to you. ???

WHY BIRDS HAVE TAILS and not canards? I'd bet because they are better solution.

Do you have any images of these Russian planes, I'm very interested

http://www.paralay.com/
Most of them are speculative but its apparent that while few canards, most have tails.

Woody, I believe you wanted and engineering argument. Well, I am not an engineer yet but I work with shapes and unlike some people I believe that you can get almost all performance information about an aircraft from analyzing its shape. I do not pretend I do. I will however try with regards to the subject of this tread.

The picture is and attempt to compare the leverage affects of 2 common and one unusual configuration. According to the books I have placed the line showing the center of gravity axis just in front of the main tire. the rests is maths.

I will give and example how to interprit the data:
The F-22 compared to the Eurofighter has 23.5 percent longer(and heavier) fuselage in front of its center of gravity. To pitch up or down that section, its its tail has 8.1% longer leverage arm, however the area of the tail is 4 times the area of the Eurofighter canard. In my book that shows more turning power on the F-22 side even without TVC.

If we look at the Yaw picture the F-22 has more area and less leverage but much bigger fuselage to turn. Therefore the Eurofighter wins in Yaw.

he Roll data shows again an F-22 advantage. It has 25% wider wing to rotate but the tail has 4 times the area and close to 3 time more leverage

The a simple F-22/F-23 comparison shows them to have equal in area tail. We also know that the airframes have similar weights. The F-23 has only 8% longer fuselage in front of the CG, yet it has 29% more leverage in the tail. Needless to say the F-23 will be more maneuverable than the F-22 without TVC in Pitch. With TVC, they are probably equal.

Overall the F-22 tail design is superior to the Typhoon in some respects but the two fall far short of the awesome F-23 V-tails in terms of available control power in all 3 axis.

Thats all again IMHO.

 

[Ogami musashi]

Yes i know tails are below the wings but Air masses flow goes downward especially at high AOA's.

True’s and make sence however if there is no wing lift (the wing as stalled) what is the reason behind the mass of flow going downwards. It may be quite the opposite, with the wing stalled and the aircraft lost its lift, the airplanes might actually be loosing altitude, in which case the air stream could be going up.[/quote]
No lift doesn't means no air movement. Actually vortex burts occrus around their axis of velocity and their axis of velocity is often downward. I'm talkin of vortex burst that is when a vortex break wich is the typical condition of air flow during high AOA manoeuvers past the 25% of the chord.

However a more realistic point of view would be to say air is going...in all ways, and non linearily.
So i assume tails would be washed from it at some AOA, and not or less at some others.

You talk about cobra and the tail position but do you know that for a SU-27 going into the 40°-70° AOA area results in departure from stabilisez flight wich means the tails do not have enough autority to bring the plane level again?
This precisely because above the 70° value the tails are not washed out anymore (because of plane velocity vector influence on the air flows movements) that the plane can recover.
So being washed out or not is quite a difficult question, depending on the plane's design.

I shall recall you one important point, the air deformation occurs at the nose first, so as you go aft the plane, everything is more and more disturbated.
Nowadays with multi layer vortex lift planes (like F-22,JSF or rafale) air is fairly modified since the noze (juste 10 to 15° AOA on a F-22/23 chine suffice to create vortices).

My aim is not to say canard are better, my aim is to say, logicaly being washed is far less possible with a canard than a tail.
(because here the problem would be the wash on the wing, but this is another topic).

Lets assume a plane is flying at 90 degrees AoA. Which will bring the nose down better? The canard can only do that with negative lift against the wing huge positive lift. I'd say its impossible for the canard. What happens if the canards is locked in its level position? It will generate even more positive turning moment trough its face drag.
Can the tail bring the wing back from this position? Certainly yes. In a typical cobra maneuver the tail is locked in its level position and thought its sheer size and drag acts to tunr the clean nose down.

This shows me that that and tail controlled aircraft will always be able to recover from extreme alfas while a canards controlled one might not.

Excuse me but, i don't see why a canard could not recover..this is only a matter of Moment Coef, wich is himself depending on AOA of the canards/tail possible and their CL.
That is...a canard have even greater CL than a wing by definition.
Now do not mix the Lift produced by the wing to stay steady (here in 90 ° AOA) and the pitch moment created by instability of a plane.
The tail/canard do not oppose the lift created by a wing, but the leverage a CL-CG(the stability margin then) by another leverage (the moment coefficient).

Tail or canards, have sufficient power to do so.

Also don't forget a tail aligned in the 90° AOA plan of the tail doesn't produce lift to rotate the plane, she just produces lift to stay in that position (if we assess this is a stable position). In order to move the plane down, she'll have to do the same thing a canard: taking an AOA and as i said, even with bigger size considering a canard has huge CL is less washed out i'm not quite sure a tail by definition is better suited.

Now, some people may have created plane that use tails finely to improve their capability.

While the canard has a definite positive pitch advantage the aft tail make up with a more potent negative pitch authority trough simple physics laws. And negative pitch actually is the High AoA enabler. The positive pitch only gets you there.

Actually i don't understand what you mean here, negative pitch on a tail pitches the plane up, so do positive pitch on a canard so i don't see differencies.
What did you mean?

But lets look at that else does the canards bring to the table.
Can it be used for Roll? Yes but it two engine fighters equal or closer to the roling axes than it the tail. Hence less leverage. (blind obvious)Also, even it we all agree then in positive pitch it is better (I do) in roll you have only one of the canards doung the positive and the other the negative, and in negative pitch the tail rules.

Again i think you mess instability and leverage.
I don't see why an aft tail would be better to achieve negative pitch.

What else. Yaw? Can canards help in yaw. Not really. Can they be made to? No because, sizing the canards to act both as yaw, roll and pitch would be...close to impossible, given pilot view requirements, affect on wing, weight impact on the forwards fuselage.
Can tails help in Yaw? Conventional ones NO. Can they be modified? YES, and the YF-23 is te perfect example of that. More on that later

Actually this is a matter of FBW. F-22 tails do it.

By the way, rafale's as been tested a 140° AOA (of course transient) manoeuvers, SU-47 at 45° AOA(sustained) i don't think this is something we can call "not good high AOA manoeuvers".

 

[DWG]

I still think its sad they can't get it together.

There are pluses and minuses to everything in aviation. A combined training establishment means you have some economies in infrastructure, but means you are less able to exactly tailor the training to your own preferences. It also means one of the partners has to provide for extra airspace usage, which is actually a fairly constrained resource (hence the existence of NFTC (NATO Flying Training In Canada), Luftwaffe Tornado training based in the States and Singaporean training based in at least three countries that I can think of).

>> but you say most of them are now retired? <<

The early DAs (prototypes) are now unrepresentative, much like the US only used the YF-22s during evaluation. OTOH they stayed representative for much longer than AA-1 (the first F-35) which was unrepresentative before it was half-built.

>> There must have been a lot going on but the advertised schedule doesn't give much of an impression of urgency.

Example: "March 1994: The first Eurofighter, DA1 makes its first flight from Manching, Germany. August 1997: DA1 flies from Manching, Germany to Warton, England to commence a two-week co-operation flight trial." That's a 3 year gap (and there's a lot more like that). <<

Most of the test flying would sound stunningly boring to the public, on the lines of repeat the previous week's test but 1000ft higher or 0.1 Mach faster, so the web pages are very much highlights rather than a reflection of all the work done. First flight itself was a politically necessary demonstration that the aircraft would fly, but there was a considerable amount of work still necessary at that point to demonstrate that it was ready to fly useful test points safely. This is about the time of the Gripen and YF-22 PIO crashes which made people were very conservative about testing new unstable aircraft.

>> Another example: "June 1998: DA3 successfully jettisons an external fuel tank (1000 ltr.). February 1999: DA3 flies for the first time with wet fuel tanks (1500 ltr) testing the functionality of the fuel system." It took them 8 months to put fuel in them? <<

Was the fuel system for the tanks ready in June 98? Was an aircraft available? Had the aerodynamics data been gathered for the 1500ltr tanks? And so on. It's not just a case of unscrewing the cap and sticking the hose in.

>> And my favourite: (DA3) "March 2004 First in-flight Gun firing achieved." Does this mean 25 years into the programme and 1 year after deliveries start only then do they fire the gun in flight? (if not its quite misleading)<<

Consider using your computer with a jackhammer strapped to the side, how well would it do? Every system on the aircraft has to go through vibration trials to make sure the vibration from the guns won't stop it from functioning. Gunfire is one of the worst things you can do to a modern fighter. Reportedly one of the Russian fighters actually had the instrument panel land in the pilot's lap during gunfire trials.

>> Your probably right but don't they need a Typhoon for radar and systems matching or are they expected to do that only after everything else is completed? I'm glad you say they have done some testing. <<

Essentially missiles are like peripherals. You hook them up to a databus and tell them what to do, then they go off and do it. As long as you have the interface defined the weapon and the weapon control system can be developed independently of each other and only brought together when both are ready. Flight trials are mostly necessary to demonstrate that the missile and the aircraft can safely separate (there are memorable films of instances where this went wrong -- you wouldn't expect a 500lb bomb to be capable of going up not down, but it's happened before).

>> I thought there was a tender out right now for targeting pod for the Typhoon? I you're right I'll never trust Flight again. <<

You seem to be confusing different stages of the tender process. The selection was made a while ago, it's the contract details that are being negotiated at the moment (how many we want, when we want them, how much support you'll provide, how little we want to pay for them). Flight has done a reasonable job of reporting it from what I can see.

>>Your idea and my idea of development seam a little different. I know the Typhoon is a fantastic aircraft and more complex than I can ever imagine but please excuse my ignorance if, to me (a layman), what you describe sounds more like getting the product finished 4 years after deliveries started. And that ongoing, unending situation has replaced what I would consider development. <<

It's the same for every aircraft anywhere. Look for references to production blocks, spiral development and the like, and each system on the aircraft will have smaller development stages within those blocks. And then there is the unexpected that has to be catered for -- consider that they only just realised the F-22's nav-system falls over if it crosses the International Date Line....

>> Its not just the Typhoon, everything seams to take longer these days. The programme has been going for almost 30 years since first envisaged, that's nearly the same time as from the end of WW 1 to breaking the sound barrier or half the time since the end of WW 2. I know things are different now but in the fifties we went through 3 generations of fighters in a decade! Technology and modern attitudes don't seam to be helping. <<

Modern aircraft are orders of magnitude more complex than those that preceded them and the performance demands placed on them mean that they are flying on a knife edge. That means that the testing has to be far more exhaustive than ever before,. Consider that YF-16, YF-22 and Gripen all had crashes or near crashes during flight trials that were caused by Pilot Induced Oscillation (which despite the name is actually a failure in the flight control system), V-22s have crashed due to the vortex-ring state that was poorly understood and in another case because a pilot had a poor understanding of the FCS. It's a rare aircraft that doesn't lose a prototype during testing and it's rare a year goes by without a test pilot or flight test engineer paying for it with his life. In the past year we've seen test-flying crashes by Polecat, LockMart's morphing wing UAV (*2), Barracuda, ARH and Boeing have seriously bent a 737-900ER -- those are just the ones that have been a) reported and b) spring immediately to mind. Even non-crashes can be very serious, there were reports a year or two ago that one F-22 might never fly again after a very high-G anomaly during testing.

 

[Trident]

Another factor that slows many military development programmes nowadays is that the impetus of the Cold War is gone. Count on it, the Rafale, Typhoon, Su-34 and F-22 all would have entered service years before they actually did if the USSR had still been alive and kicking.

 

[lantinian]

Hi Everyone,

I would like to place a topic of certain heated discussions where it belongs.
Here was the start"

http://www.secretprojects.co.uk/forum/index.php/topic,1624.msg13544.html#msg13544

and it continued here as well at the same time

http://www.secretprojects.co.uk/forum/index.php/topic,1092.msg14278.html#msg14278

So for the benefit of everyone, I will try to look into the canard / tail debate from an operational perspective. When is it good to have canard and when a tail. Of course from purely aero dynamical point of view is best to have both, like the SU-30MKI

As we have stable/unstable designs and canard/tail design we end up with 4 possible configurations. canard.

Picture one shows how efficient are the 4 configuration in a subsonic cruise. This is a regime good long range aircraft and aircraft that are efficient here are designed to have long ranges. This picture clearly shows that the Eurofighter was not designed to be a long range fighter.

Picture 2 shows the lift efficiency in Supersonic speed. Here the stable canards are most efficient as exemplified by the Viggen. BTW XB-70 Valkyrie is also a stable canard which is another proof to this.

The F-23 design could also be on top have I considered its designers opinion. However for the purpose of this comparison I would consider it a standard unstable rear tail design, like F-22A and SU-27.

So far if we need long range we should choose stable canards for Supersonic Cruise and unstable design with rear tail for Subsonic Cruise

TO BE CONTINUED...

lantinian

 

[sferrin]

Going along with your post that's why Tomcats had the glove vane that deployed at supersonic speed. It moved the CP forward to unload the tail and keep the aircraft from becoming TOO stable. That's why it was able to pull 7+ Gs at Mach 2, something I don't think anything outside the F-22 can do. Of course they eventually pinned them shut and left them off the D's altogether because they didn't get used enough to justify their existence. . .

 

[elmayerle]

Ah, but the Tomcat21 changed the planview of the aircraft in that area to get the same effect at high speed with tailored LERXs.

 

[lantinian]

Thanks Guys,
That is realy was realy an enlightment for me. I knew about that but never thought about its use.

I will however try the keep my next post at clear from non standard configurations as just so that the comparison is correct for a broder range of aircraft and you have a chance to ad solutions like that.

regards,
lantinian

 

[Woody]

Hi Lantinian. So this where you're at my friend.

My Mistake :-[. Its the Center of Lift that moves forward in supersonic flight.

Glad to see you're finally agreeing with Ogami Musashi. ;D

But isn't a bit boring to compare canards and tails on cruise efficiency alone?

Anyway let me get this right; Canards and stable tails are inefficient at subsonic speed? Someone had better tell Burt before he does something silly.

Cheers, Woody