• Hi Guest! Forum rules have been updated. All users please read here.

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

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
They built them into the XB-70, the HiMAT and the X-31, Burt Ruttan likes them and all the compeditors for the ATF/F-22 and JSF/F-35 contracts initially considered them but in the end they all rejected cunards. Why? Do they really believe they can get better maneuverability/stealth/STOL out of a conventional wing and tailplane. If you're going to tell me they were too late, like forward swept wings (not that I'm a fan), they'd both been around for decades. Somebody help me out here - it's bugged me for years.
Cheers, Woody.
 

Matej

Multiuniversal creator
Joined
Feb 13, 2006
Messages
2,616
Reaction score
117
Website
www.hitechweb.genezis.eu
I think that till 70s, they didnt use the canards because without digitally supported flight control systems they were uneffective. You need a redundantly metastable plane to take some effect. After 70s, well, probably for the USA was the primary factor stealth. European´s and russian´s philosophy was aimed to the high maneuvrability, so a lot of their designs have canards.

BTW, welcome on Secretprojects ;)
 

Orionblamblam

ACCESS: Above Top Secret
Top Contributor
Senior Member
Joined
Apr 5, 2006
Messages
7,916
Reaction score
1,164
Website
www.aerospaceprojectsreview.com


Damn you, Cunard! America hates you!!!
 

Kim Margosein

ACCESS: Confidential
Joined
Feb 10, 2007
Messages
103
Reaction score
5
Are you speaking commercially? I think it's because people expect commercial aircraft to look like commercial aircraft. Examples:

1. Beechcraft Starship. 50 were built, about 10 were sold. Beechcraft finally bought them back so they wouldn't have to deal with supporting them.

2. Piaggio Avanti- Virtually all were "sold" to the Italian government.

3. Boeing SonicCruiser- DOA.

Kim Margosein
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Thanks Matej for the quick response but I still don't get why cunards aren't steathy. A coventional tail levers downwards to effect pitch up detracting from the wing's lift, requiring it to be larger to do the same job, all else being equal. Both the F-22 and F-35 have long parallel sides between the intakes and wing that would happily accommodate cunards even before you start moving the wing aft as would be logical with extra lift up front (perhaps because that was how they were designed in the first place?). The F-23 has an excuse as the elevators serve as rudders for yaw control but not the Lockheed designs with their barn-door semi-vetical fins (how are they steathy?). Re. the flight controls, the Rockwell Sabre-bat, X-29 et al were conceived in the mid 70s and they had cunards and FSW! And did Burt Ruttan's kit planes have digital flight controls or a 'redundantly metastable' do-hicky? (only kidding-but seriously...)
Still bewildered, Woody
PS: how do you attach images. When I press the 'Instert Image' button, I just get
typed. Is this an HTML thing or a Firefox thing. Any help appriciated as I'd love to attach some JSF concepts to illustrate my point.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Cheers Kim, I hadn't even concidered comercial aircraft but now you mention it why haven't Boeing and Airbus tried a serious cunard configuration without trying to re-invent some sort of half-arsed concord? You would think if they kept the speed as it is they'd save passenger-gallons per mile, as the trim drag should be better, and at the end of the day that's airlines care about. As for private aircraft I guess fashion is a factor but the Piaggio Avanti you speak of is doing quite well these days and has re-entered production if Flight Global is to be believed (but technically that's a tri-plane as it has a tail as well). But this getting off the subject as it's military jets I'm really interested in.
Woody
 

Sundog

ACCESS: Top Secret
Senior Member
Joined
Aug 2, 2006
Messages
2,821
Reaction score
267
I have yet to see any reliable information that says canards can't be as stealthy as conventional tailed designs. The main reason the U.S. doesn't have canards on it's fighters is that a conventional tail is better than a canard in terms of trim power over a large range of angle of attack and a conventional tail can trim an aircraft at high alpha better than a canard in general.

However, a canard arrangement usually allows you to make a smaller aircraft for the same mission. A smaller airplane is a lower cost airplane, which is the main reason the European fighters have canards. America hasn't been as constrained by costs as most other countries, so they haven't had to go with canards.

Also, in terms of three surface aircraft like the Su-35, it's been found that if you have thrust vectoring you don't need the canards. This partly explains, assuming they're accurate, why the new Russian fighter designed by Sukhoi concepts that have been shown in artists renderings don't have canards like the Su-35.

It also has to do with mission optimization. If canards offered any advantages over a conventional tail in a highly maneuverable supercruise fighter more of the ATF submissions would have had them. I believe only the Grumman submission had them. My guess is, besides the trim capabilities, a canard is more difficult to integrate into the design for low supercruise drag than a conventional tail. Considering the F-22 supercruises at M=1.8, much higher than any other fighter out there and the fact that canards obstruct the pilots view, there are more reasons not to use them in a pure fighter, than to use them, other than cost.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Cheers Orionblamblam, I'm always happy to get spelling corrections, I'm more a pictures person, anyway 'canard' is a stupid word, doesn't it mean duck?
Also thanks Sundog: if you know any open source internet stuff that explains these sort of dynamics please let me know (see my 'Down turned wing tips' answer).
And I'm sorry but conventional tails look boring to me.
Thanks Overview for the attachment advice, hope I've got it sussed now. Why New Zealand? Did you read my blurb about it in my 'introduce myself' bit.
Here's a 2 year old design of mine, please don't steal it as hope to publish it some day and I can't afford a lawyer.
Regards, Woody
 

Attachments

  • AttackFighter72dpi.jpg
    AttackFighter72dpi.jpg
    76.8 KB · Views: 492

dan_inbox

ACCESS: Top Secret
Senior Member
Joined
Sep 3, 2006
Messages
770
Reaction score
297
Kim Margosein said:
...because people expect commercial aircraft to look like commercial aircraft. Examples:
1. Beechcraft Starship. 50 were built, about 10 were sold.
2. Piaggio Avanti- Virtually all were "sold" to the Italian government.
3. Boeing SonicCruiser- DOA.
The Vari-eze / Long-eze being notable exceptions.

And Woody, Canard is the French for Duck. Airplanes with the main wing located way back are reminiscent of a duck in flight.
 

overscan (PaulMM)

Administrator
Staff member
Joined
Dec 27, 2005
Messages
12,438
Reaction score
3,455
Woody said:
Thanks Overview for the attachment advice, hope I've got it sussed now. Why New Zealand? Did you read my blurb about it in my 'introduce myself' bit.

My wife is from New Zealand, she would like to like to return there to have children.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
My wife is from New Zealand, she would like to like to return there to have children.

NZ's a nice place if you like surfing or skiing and cheap steak (which I do, now being in Japan where it cost a fortune) but don't expect your kids to have a career in aerospace unless you count crop dusters. Strangely they do have a lot of pilot schools though. Good luck with it and I hope you keep up the website from there.
Cheers, Woody
 

Firefly 2

ACCESS: Secret
Joined
Jun 30, 2009
Messages
461
Reaction score
8
Woody said:
Cheers Orionblamblam, I'm always happy to get spelling corrections, I'm more a pictures person, anyway 'canard' is a stupid word, doesn't it mean duck?
Also thanks Sundog: if you know any open source internet stuff that explains these sort of dynamics please let me know (see my 'Down turned wing tips' answer).
And I'm sorry but conventional tails look boring to me.
Thanks Overview for the attachment advice, hope I've got it sussed now. Why New Zealand? Did you read my blurb about it in my 'introduce myself' bit.
Here's a 2 year old design of mine, please don't steal it as hope to publish it some day and I can't afford a lawyer.
Regards, Woody

That is some nice design. :eek:
Is there a specific reason wgy you opted for the inverted double delta?
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Firefly said:
Is there a specific reason wgy you opted for the inverted double delta?

Ah, don't get me started. I wanted to make a compact shape as I envisioned it as a carrier based fighter/attacker. The forward swept outer main wing has a lot of area without using up too much edge 'real estate' needed for the canard placement - which is also forward swept; to minimise the number of radar return 'lobes' and since I wanted to put it behind the intake so as not to obstruct it or the pilots vision, I thought it would be good to reach as far forward as possible for control purposes. Obviously FSWs have got all the other airflow boundary layer separation benefits as well which probably wouldn't hurt. I wanted to make the outer wings all-moving for a bunch of more secret reasons but how that would work with a carrier folding wing I don't know. Otherwise the plane's optimised for stealth from below with a flattened underside, for low observability from ground defenders or for the look down - shoot down roll. The intakes are supposed to open from below at high angles of attack but the 2D shape necessary for this presents some nasty 90 degree angles from the side above. Like I said it's about 2 years old and needs some area-ruling but I still think it's got a few features that would benefit current planes.
Thanks for the interest, Woody
Any other comment gratefully received (as long as they're nice).
 

Attachments

  • AttackFighter72dpi.jpg
    AttackFighter72dpi.jpg
    76.8 KB · Views: 271

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
These would have been much cooler JSFs. I did have a BAe canard concept but it's gone. I know a lot of people don't think the X-36 was a JSF but MD would say that after they'd lost. Anyone got any more?
Cheers, Woody
 

Attachments

  • 1x-36-2585113.jpg
    1x-36-2585113.jpg
    28.5 KB · Views: 313
  • x35pm.jpg
    x35pm.jpg
    27.1 KB · Views: 353

Sundog

ACCESS: Top Secret
Senior Member
Joined
Aug 2, 2006
Messages
2,821
Reaction score
267
Somewhere I have an article on the X-36 that shows what a Naval version would like, in planform. If I run across it I'll scan it in.
 

elmayerle

ACCESS: Top Secret
Senior Member
Joined
Jan 8, 2006
Messages
1,350
Reaction score
119
Woody said:
These would have been much cooler JSFs. I did have a BAe canard concept but it's gone. I know a lot of people don't think the X-36 was a JSF but MD would say that after they'd lost. Anyone got any more?

Well, going by published illos of the McDD proposal, there are great similarities, but the two are not of identical planform (as I remember, McDD's entry had tail surfaces similar to the YF-23, but I may mis-remember). I'm told that the aerodynamicists at Lockheed considered the McDD configuration a much more formidable adversary than the Boeing one and it was only McDD's violation of the rules of the competition (separate lift engine after their gas-driven lift fan concept failed utterly - the rules were one engine for lift and propulsion - X-35B/F-35B propulsion system can be considered an extreme case of the "tandem fan" concept) that got them disqualified.
 

Matej

Multiuniversal creator
Joined
Feb 13, 2006
Messages
2,616
Reaction score
117
Website
www.hitechweb.genezis.eu
You can see everything about MDD and others JSF development at my web:

http://www.hitechweb.genezis.eu/xjsf.htm

I will write a short related summary later, but now I am too busy @ work.
 

elmayerle

ACCESS: Top Secret
Senior Member
Joined
Jan 8, 2006
Messages
1,350
Reaction score
119
Yep, those illustrate the GCLF (Gas-Coupled Lift Fan) concept quite well. Unfortunately, the gas-coupling didn't work that well and they went with a separate lift engine instead of a mechanically-coupled lift fan like Lockheed did. If they'd gone with the same mechanical-coupling, you might have had two aircraft using the same basic concepts, but it would've been, IMHO, a much closer competition. That top view of the JAST1 equipment arrangement isn't that fair off that of the X-35/F-35 except for the gas-coupled lift fan. The fuselage right around the lift fan looks very similar, I wonder if the same partner would've produced it for this aircraft as does produce it for the F-35?
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Matej said:
You can see everything about MDD and others JSF development at my web:
http://www.hitechweb.genezis.eu/index.htm

Thanks Matej. So you're the amazing 'hitechweb'! Awesome collection of material - just what I was after. I have to limit myself to the pictures as I can't read your language (which is?) but it still looks pleasantly familiar compared to Japanese, that I'm learning at the moment. You have so much stuff, but I have a little difficulty navigating. On some pages I can't find a home page button and some of the links like: Aircraft Index, Stealth Technologies and Flying Wings don't load for me. Maybe I need to buy your DVD?

Thanks, CammNut and elmayerle. All the competitors seam to have considered all the options. Boeing/Rolls royce seam the only ones to try the Pegasus type nozzles though, poor buggers. It's a pity MD chose the gas driven fan over a mechanical link other wise they would probably still be (independently) with us and we'd have a much more bio-diverse aerospace industry.

Just like the car industry, there where some fantastic concepts but by the time they reached the showroom they'd all turned safe and boring. 'IMHO' it was big mistake to lump the VSTOL replacement in with the F-16 replacement for the competition. It has hamstrung the industry for the long-term future. I would have preferred a VSTOL for the Harrier/A-10(/AH-64?) and stealth HiMAT for the F-16/18 roll.

Am I right in thinking the F-35 uses none of its vectored/ducted thrust for in-flight maneuverability?, if so its a tragic waste. And since they did go for a common platform, why buy a VSTOL then rip out the VSTOL bits? A bit like buying a folding bicycle over a racer and then welding it unfolded because you have garage (what if you want to take it on the bus?). I know it saves weight etc. but so would a dedicated airframe. Oh well...

But opinions are boring - without pictures! Here's my latest creation (if didn't see it already). It took me a whole lunchtime.
 

Attachments

  • AAH-47 Tandem Seat Gunship.jpg
    AAH-47 Tandem Seat Gunship.jpg
    85.9 KB · Views: 371

overscan (PaulMM)

Administrator
Staff member
Joined
Dec 27, 2005
Messages
12,438
Reaction score
3,455
Woody - please try to stay vaguely on topic. Fantasy art should stay in "The Bar" please.
 

TinWing

ACCESS: Top Secret
Senior Member
Joined
Jan 3, 2006
Messages
888
Reaction score
49
CammNut said:
Woody said:
I know a lot of people don't think the X-36 was a JSF but MD would say that after they'd lost.

The X-36 was based on an early iteration of McDonnell Douglas's JSF design, produced under its precursor the Joint Advanced Strike Technology (JAST) research programme. While the design continued to evolve, MDC spun off its JAST 1 configuration and built the subscale X-36 as an unmanned tailless-fighter demonstrator.

These diagrams show the early evolution of the eventual MDC/BAe JSF design.

The cutaway "MD JAST 1.JPG" is especially interesting, as it deletes any tail control surfaces. Overall, these drawing resemble BAE Systems "Replica."

What is the original source, and is there any chance of a higher resolution scan of the "MD JAST 1.JPG" cutaway?
 

elmayerle

ACCESS: Top Secret
Senior Member
Joined
Jan 8, 2006
Messages
1,350
Reaction score
119
Woody said:
Am I right in thinking the F-35 uses none of its vectored/ducted thrust for in-flight maneuverability?, if so its a tragic waste. And since they did go for a common platform, why buy a VSTOL then rip out the VSTOL bits? A bit like buying a folding bicycle over a racer and then welding it unfolded because you have garage (what if you want to take it on the bus?). I know it saves weight etc. but so would a dedicated airframe. Oh well...

The F-35B does have some fan vectoring capability in hovering flight, but not in normal flight (then again, neither did Boeing's entry). The basic core equipment and structural interfaces are common to all three variants, but the other two have an extra fuel tank where the F-35B has a lift fan. There are definite structure differences at the detail level between all three versions, but the assembly fixtures are such that they'll work with any variant; that's one of the major improvements over a number of other designs.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
elmayerle said:
The F-35B does have some fan vectoring capability in hovering flight, but not in normal flight (then again, neither did Boding's entry). The basic core equipment and structural interfaces are common to all three variants, but the other two have an extra fuel tank where the F-35B has a lift fan. There are definite structure differences at the detail level between all three versions, but the assembly fixtures are such that they'll work with any variant; that's one of the major improvements over a number of other designs.

Thanks TinWing,
I'm sure there are good pragmatic reasons for a common platform but with the VSTOL removed for the USAF and US Navy and I realise the decision was made a long time ago in Washington but from this dreamers point of view it's a pity. Wouldn't it be great if the Air Force and Navy could fly their plains off Marines assault ships or from forward dispersed bases. Also the US Navy could disperse some of it's plains away from the big target super-carriers to smaller ships. I would have thought the USAF/USN would be into it as they could create smaller, more numerous naval task-forces or be much more relevant on land up front with the troops (or is that the problem?).

As for no thrust in-flight vectoring on the F-35, I still think its a crying shame. I hope it's not just to keep off the F-22's patch. The F-22 with its speed and super systems has far less need for agility that a close support fighter, don't you think?

I just can't get over those clips of the X-31 defying gravity with thrust vectoring (a canard configuration, just to bring things back to the thread subject, Overscan), what a waste to leave it out. Enjoy the X-31 in action in the Youtube clip below:-

http://www.youtube.com/watch?v=PNHhDfUmp2I

Cheers, Woody
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
TinWing said:
The cutaway "MD JAST 1.JPG" is especially interesting, as it deletes any tail control surfaces. Overall, these drawing resemble BAE Systems "Replica."

Replica was a once a canard? This is all I got - got anymore?
Cheers, Woody
 

Attachments

  • BAE 'Replica' Stealth Aircraft.jpg
    BAE 'Replica' Stealth Aircraft.jpg
    13.1 KB · Views: 232

TinWing

ACCESS: Top Secret
Senior Member
Joined
Jan 3, 2006
Messages
888
Reaction score
49
Woody said:
TinWing said:
The cutaway "MD JAST 1.JPG" is especially interesting, as it deletes any tail control surfaces. Overall, these drawing resemble BAE Systems "Replica."

Replica was a once a canard? This is all I got - got anymore?
Cheers, Woody

No, but the overall configuration of "Replica" is very similar to the early MD JAST proposal, as would be expected because BAE partnered with MD and NG in their failed JSF bid.

Replica might be a bit larger, but the configuration has an unmistakable visual similarity with the failed McDonnell Douglas proposals.
 

Matej

Multiuniversal creator
Joined
Feb 13, 2006
Messages
2,616
Reaction score
117
Website
www.hitechweb.genezis.eu
Woody said:
Thanks Matej. So you're the amazing 'hitechweb'! Awesome collection of material - just what I was after. I have to limit myself to the pictures as I can't read your language (which is?) but it still looks pleasantly familiar compared to Japanese, that I'm learning at the moment. You have so much stuff, but I have a little difficulty navigating. On some pages I can't find a home page button and some of the links like: Aircraft Index, Stealth Technologies and Flying Wings don't load for me. Maybe I need to buy your DVD?

Thanks. Hitechweb is written in Slovak language and because I moved to the new server, some parts (like index of aircrafts, stealth technologies, etc.) are still missing.

http://www.secretprojects.co.uk/forum/index.php/topic,1474.0.html

TinWing said:
The cutaway "MD JAST 1.JPG" is especially interesting, as it deletes any tail control surfaces. Overall, these drawing resemble BAE Systems "Replica."

What is the original source, and is there any chance of a higher resolution scan of the "MD JAST 1.JPG" cutaway?

There is still a chance, but I think that this is, ehm, a bit sensitive material for public use (yet).

_____________________________________________________________________
Here are two final MDD JAST/JSF studies - first is the only JAST related study with canards - JAST-9B and second is final JAST-10 variant.
 

Attachments

  • JAST9B.jpg
    JAST9B.jpg
    46.3 KB · Views: 186
  • MDD-JSF-2.jpg
    MDD-JSF-2.jpg
    42.6 KB · Views: 175

Tam

ACCESS: Confidential
Joined
Jan 6, 2007
Messages
74
Reaction score
1
I google translated this from a Chinese article analyzing the J-10's performance and aerodynamics. It appears to be an interview. Aside from the robot generated grammar, you can dig pieces from the text that gives you an idea.


March 21, 2007 : 07 A 30 F-10 fighters used by the aviation knowledge canard configuration. This is the first time that China successfully developed a Chinese fighter. The family of fighters in the world, some of the more advanced fighters used a similar layout, Sweden's Saab a 37 "Thunder", the JAS 39, the French "Mirage" III NG, "Mirage" 4000. "Gust of Wind," and Israel's "young lion" C2 "lion" Russia's MiG 1.44 EF2000 development of the cooperation between the four countries in Western Europe and "Typhoon." With the in-depth development of aviation technology, a new program emerging duck fighters, and among the ranks of advanced fighters.

Well, what the fighters duck layout features its aerodynamic characteristics and how?

After the end-use of high speed and low speed, and no good end of the general layout of the high-speed aircraft pneumatic Due to various reasons, its slow performance is often ineffective. And duck layout of the fighters were able to meet the high velocity. Performance requirements. This layout will be good for high-speed aircraft to take care of the slender body shape and aircraft landings on the short-range or high-level allocation coefficient. This is because : on the one hand, slender ducks layout in the transition from subsonic to supersonic. The focus of the movement of the end-to stability after more than a small increment, which is beneficial for high speed flight. Other hand, in high angle of attack, or approaching flight, it can produce the end-and no later than the end of a much higher trim lift aircraft. This shows that it is also suitable for low-speed flight. Balancing lift plans high-end after the first set began, and duck-tailed aircraft longitudinal trim the way maps. Unsteady flying level and in the air do, and lift its gravity, thrust and resistance is equal, the whole plane is balanced torque. Offered peace force F-10A for a duck with the early F-layout program in China although there were a concept embodied 9, But the many technical problems involved in the F-1 tester access is the ultimate solution Liu Ying caption perfect pitch. Tail-end and after the aircraft without the need to pay a certain price for the lift. During the flight, the lift-wing aircraft or torque Mzo Y and the entire focus of the aircraft to generate a bow torque. To balance this moment, there should be no partial aircraft movements tail fins, tail after the aircraft to tilt on the elevator. Lift to trim to produce a negative result dropped the whole plane lift. Of course, when the level of attack is not the end of the load, it is a small price to pay to the lift. However, when the aircraft to fly at high angles of attack, and to take measures to increase or (up wing) on the situation worsened. Would have risen greatly because of the additional torque bow. To trim those additional torque, the horizontal tail edge too great to be on the point, it will have risen remarkably dropped arrived. If a wing or a high-growth approach. Balancing the sometimes very difficult, but bear in the horizontal tail lift height of the measures taken.

This is no shortage of examples. The F-4 aircraft in the United States after taking an edge flap boundary layer control technology, bow torque increase substantially. The results they have already allocated nearly stall in the tail, but the end of the peace process, upswept front. The airfoil-bending will become. Japan's PS-1 seaplane was on the tail surfaces to increase the negative inflatable lift. After the end layout like this, no tail-plane balancing the rising power is even more difficult. In contrast, duck-tailed and no later than the end of the layout-layout advantage : Pitching torque from its rise before the aircraft is the focus of UAVs (canard). This is really killing two birds with one stone : it provides a balancing torque, increased lift.

Then why do people seldom used before duck layout?

This is because the ducks conventional aircraft has three drawbacks : (1) There is a strong wing to wing before the next wash, lower wing lift. Despite the lifting of the front wings that are partly offset the loss of lift, but not necessarily lift the total allocation usually much higher than the after-tail.

(2) Hollywood-style layout not solve problems of distribution. Under normal circumstances. Canard load than the tail, the tail often as 3-4 times. Because if canard put in front plane followed focus forward and center forward adjustments are required. This canard from the center of gravity of the past, Arm short, it's balancing capability is limited. In addition to the main wings on the front wings are washing, in the first easy-wing stall angle of attack before. This landing and take-off maneuver at high angles of attack is negative. Swede end of the last century until the 1960s, successfully developed a 37 Saab aircraft, These shortcomings will be overcome to a certain extent. As M-2 level for the aircraft, Saab 37 not use a complex risen measures to enable the taking off and landing on short distances N400 m, meet the requirements in a short distance and landings. This success has attracted widespread international attention. Saab is one of 37 adopted a close-coupled canard layout, the use of the favorable after-wing detached vortex interference between a rising power.

(3) The vortex from the surface of the main wing formation, development, and the breakdown of the aircraft lift and horizontal drift of the torque characteristics of a great impact makes nonlinear longitudinal torque curve is very serious, and lead to a deterioration of aircraft steering stability. In order to solve this problem, the conventional canard airplane had increased the stability of the aircraft, to seek more straight vertical torque curve. As a result, the aircraft's increased resistance to trim, trim capacity of the front wings, aircraft taking off and landing of the maneuverability and performance deterioration. One of the solutions is the use of fly-by-wire system, relaxed static stability.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Wow Tam. Not quite sure I followed that, especially the bit about "Hollywood-style layout not solve problems of distribution" but I didn't find anything that disagreed with my belief that canards are generally a good idea for a maneuverable aircraft with a wide speed range. And the author seams to have 3 good reasons. Does anyone out there read Chinese and could give us the gist, cause if so, Tam, maybe you can post the original 'link' and they can give it a go.
Cheers anyway, Woody
 

Deino

ACCESS: Top Secret
Staff member
Top Contributor
Senior Member
Joined
Jan 2, 2006
Messages
2,732
Reaction score
505
Woody said:
.... maybe you can post the original 'link' and they can give it a go.

I think it's this one !

http://www.wforum.com/specials/articles/04/33492.html
 

Tam

ACCESS: Confidential
Joined
Jan 6, 2007
Messages
74
Reaction score
1
One thing I have to mention is that the Americans have a very different concept when it comes to their runaway requirements. The USAF (not the USN) seems to plan their aircraft always enjoying long, smooth concrete runaways. The Euroopeans---and most especially the Swedes---have a very different notion. The Europeans live under the constant fear (during the Cold War) that their runaways would be taken out by ballistic missiles, air attacks and Spetnaz special forces. So they prefer runaways that are short, aircraft that can easily take off from rough improvised runaways, and even highways. Its not surprising that the Israelis, surrounded by hostile Arab nations, share a similar notion. Canards do factor into STOL performance, that is undeniable.
 

dan_inbox

ACCESS: Top Secret
Senior Member
Joined
Sep 3, 2006
Messages
770
Reaction score
297
Sentinel Chicken said:
So why aren't there more canard equipped aircraft with the IDF, then?
The IDF has been bullied by the dear allies ::) into an all-F-16 operation.
When it still hoped to have the means, it was developing the Lavi.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Tam said:
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
 

Attachments

  • F-15B ACTIVE.jpg
    F-15B ACTIVE.jpg
    108.7 KB · Views: 172

Sundog

ACCESS: Top Secret
Senior Member
Joined
Aug 2, 2006
Messages
2,821
Reaction score
267
As I posted earlier, the main reason for going with canards in Europe is lower cost than a conventionally tailed aircraft. 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). It's also a fact that the ATF was designed to out maneuver everything and anything in the sky and the majority of submissions had conventional tails. It isn't because the U.S. likes or dislikes canards, it's because when all of the calculations are said and done the conventional tail is the best configuration available for the mission given the current state of technology.

As for the F-35's maneuverability, remember, the F-35 is really designed to replace the F-16, F-18, Harrier, and A-10 in the U.S. military. All of those platforms are used mainly as bomb trucks. The U.S. Military will use it's F-22s and F-15s as their main fighter force. Therefore, they aren't that interested in supermaneuverability in the JSF platform. Having said that, though, taking into account the massive amount of thrust the F-35 has it's energy state will most likely be much higher than any other fighters out there and with it's large percentage of fuel weight fraction it will be quite a bit more capable than any other fourth generation fighter out there. Couple that with it's systems and stealth and the F-35 is a giant leap beyond many of the platforms flying today in terms of mission capability.
 

Tam

ACCESS: Confidential
Joined
Jan 6, 2007
Messages
74
Reaction score
1
I don't see how going with canards create a lower cost aircraft. Unless you find someway to neutrally trim the aircraft, a canard-delta will result in negative stability, due to two factors. First the center of lift is moved forward by the canards. Second, at the same time, due to construction reasons to have space to incorporate canards, the main wing, resulting in a CG shift to the rear. Add the large tail to that. Normally moving the wing to the rear also results in a CL shift, but due to the canards the CL is always at front of the main lift center of the wing itself. This means the aircraft is dependent on an FBW.

To say that canard delta isn't capable of high AoA is not true. You mean its more like having difficulty in getting high AoA at low speeds. But that is true with all delta winged aircraft, whose wing sweep certainly don't help on this. Canards actually give deltas higher AoA because they produce vortices, though this is more true of the close coupled canards (J-10, Rafale, Gripen, Lavi) as opposed to distanced canard configuration on the Typhoon. This enables them to get very high instantaneous turn rates (in excess of 30 deg/s). Moving the CG to the rear as I explained on the top also helps in getting higher AoA.

A problem in high AoA is to get air feeding into the intake. Ideally, the best is to use a LERX that can divert a compressed layer of air under the edge and into the engine intake. That's why we got engine intakes located under LERX; Flankers and Hornets are very good examples of this. This is more of a problem with a canard design like the Gripen and the Viggen, where you lack any device that can help divert the air into the intake. The Typhoon, Lavi, and J-10 uses the example provided by the F-16, use the flat surface under the nose to help divert the air. The Rafale has the best example, the way the nose scoops from a canted side to a LERX like extention on top of the intake, acts as a way of diverting air into the intake at high AoA. You won't bother with this kind of design if the aircraft isn't intended to fly in high AoA.

As vortice generators, canards can be trimmed level in straight flight, to reduce drag as much as possible. A vortice generating device like a LERX on the other hand, is a fixed implement, and will continue to create drag and various wave fronts behind its wake even on straight flight.

Adding TVC is only for low speed maneuvering. TVC lacks the control authority you get with aerodynamic devices once speed gets high. With the canards having an uninterrupted airstream, you have excellent pitching authority for a smaller less draggier control surface, despite the short arm lever movement you get with close coupled canards (not with a distanced canard like Typhoon). Control authority is a problem at high speeds, which is why in the fifties, once planes hit supersonic, everyone shifted to all moving control tail surfaces rather than the half moving half fixed devices you see in WWII and the Korean war. In order to get the pitching authority with a conventional tailed design, you also have to move the control surfaces back as far as possible from the plane's center, which acts like the fulcrum of a lever. That means extending the plane's length further backward, or adding structural booms. All of that adds weight on their own.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
291
Reaction score
5
Website
www.freewebs.com
Thanks Sundog, I'm sure the F-22 and F-35 will be extremely potent aircraft when the get them fully operational. And thanks Tam for taking the pro-canard corner.

But at the risk of being sacreligious perhaps angle of attack is not the point of fighter plane maneuverability. There are some times you want to do it (like air shows) but if you want to maintain any sort of energy, placing your aircraft flat-on to the direction of flight is not the way.

We would all perhaps agree that being able to sustain a rapid rate of turn is good thing in a dog fight and different configuration do this with different AoAs. A convention aircraft pitches up (into the turn) by having its tail push downwards (away from the turn); moving canard wings do this by pushing upwards (into the turn) adding to main wings turning power. I suggest that given the same wing performance the conventional aircraft will require a greater AoA to achieve the same radius turn/turn rate. And a higher AoA would normally mean more drag and more difficulty maintaining the rate of turn.

A spurious analogy might be a grand prix car compared to a drift car. A grand prix car tries not to swing out the rear end as, in spite of pointing the car towards the centre of the turn, this loses speed. Another dodgy car analogy is a conventional tail on a plane is like steering with the rear wheels on a car (a bit). :D

There are other factors to be considered like the fact that human beings can only stand about 8 Gs ,so if you're going to turn at a high rate you have to be traveling more slowly so as not kill the pilot. Canard aircraft are recognised to generally perform well at lower speeds as demonstrate by their STOL abilities.

Yet another factor in maneuverability is roll rate. Most aircraft loose the ability to roll as Alpha increases. The Eurofighter (a canard) has demonstrated excellent high Alpha roll ability.

As to canards needing thrust vectoring for pitching power, I've already said I'm not convinced AoA is everything and secondly, you'll get no arguments from me that thrust vectoring is a good thing (as it is on the conventional tailed F-22). And I'm not convinced that thrust vectoring is so useless at high speed. I thought the F-15B ACTIVE achieved good results at supersonic speed.

Tam, I agree the close coupled canard helps to stabilize the airflow over the wing at high Alpha but I think canards and conventionals can both be more or less stable dependent on the relative centre of gravity. There is also the movement of the centre of lift at different Mach numbers to be considered and as to LEX and air intake position, that a whole other 'bowl of toe nails'.

Sorry to go on but you guys have given me a lot to think about.

Cheers, Woody
 

Similar threads

Top