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kiwinopal

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  • in reply to: Mexican made aircraft. The 1920 Mexican helicopter #1140094
    kiwinopal
    Participant

    Here is the Sea Teul Zacatecas, an aircraft designed by Sea but based upon the Consolidated-Fleet 11A and Spartan C-3, built in 1933 by Talleres Generales de Aviación, only a single example ever flew.

    in reply to: Mexican made aircraft. The 1920 Mexican helicopter #1140108
    kiwinopal
    Participant

    Tragic that the designer Lascurain died in the accident. The photos give the impression it nosed over during a forced landing.

    Roger Smith.

    It was a take off attempt that failed, and indeed looks like a forced landing because probably they tried to land the aircraft after aborting the take off attempt.

    Here i leave you one of the Antonio Sea aircraft, the Sea 4 designed by TNCA in 1926, only one was made but it suffered stability troubles so it never was inducted into mass production or service and the project was terminated.

    in reply to: Canards and stealth. . . #2388143
    kiwinopal
    Participant

    Yes!
    And next generation these will follow europe, china and korea!

    Europe will take 20 years to make it they do not need it having F-35s right away, China still is copying Russia and the next generation of chinese will have more constraigns to get technology transfers from either Russia or the USA.
    T-50 has indian money and no Ukraine to bribe this time like in the Al-31 and Su-33 Technology Transfers by Ukraine to China.

    in reply to: Beauty Contest: T-50 vs F-22, -35 etc #2388148
    kiwinopal
    Participant

    F-22 it is the best looking
    http://www.ausairpower.net/F-22A-SDB-Drop-070905-F-9999W-011-S.jpg
    and the F-35 is not bad looking
    http://www.murdoconline.net/2007/f35b-thumb.jpg

    The T-50 is okay but …….uhmm still there are things i do not like and until i do not see the production version i would say it is tied with the F-35

    in reply to: Canards and stealth. . . #2388191
    kiwinopal
    Participant

    Yes well, that’s what I said, not you, so what’s your point?
    You came with the idea of level flight and canard downwash killing the lift, in the first place.

    Canards may have cambering and may have not one.
    It’s pretty obvious that J10 canard’s profile doesn’t follow fuselage “footprint”, so no you can’t deduct cambering from that.

    Anyway this is beside the point and the real point you’ve been missing is, apart from permanently and incorrectly quoting documents without understanding, that you assume canard designers are idiots who put enough cambering on canards, so that those blow under the wing??!!
    These are the grounds for your entire idiotic anti-canard case and guys from Dassault and SAAB that produced coupled canard-wing system, actually designed their canards to blow under the wings??!!
    C’mon Kiwi, man…:D

    To that, I can only respond with, what if the guy that designed F16, put it’s LERX stream over the wing root, while twisting the wing towards the tip, to create washout?

    BTW, wing has much larger downwash than canard and when a tailed RSS plane’s wing starts to blow into the elevator’s high pressure area (when “contributing” to lift :D), how much such elevator actually lifts and how much is a dead drag and why does an elevator need to be large and strong?

    My answer is Russia chose
    http://cdn.globalaircraft.org/media/img/planes/lowres/su-27_1.jpg
    america chose
    http://www.1stfighter.org/F22/27FS/F15F22overLangley_bloker.jpg

    and russia decided
    http://media.techeblog.com/images/t_50_pak_fa.jpg

    answer Russia and US have taken tailplanes in the most advanced stealth designs of 2010

    No MiG-1.42 no S-37 Berkut, No X-29, no X-36 were ever chosen

    in reply to: Canards and stealth. . . #2388225
    kiwinopal
    Participant

    The higher the number of ARt/ARw, the more the drag of surface.
    Notice: with same span ratio and ARt/ARw your tail’s Cl is at less 0.7
    See the blue line in graphe below:

    In total lift tails have the edge, whatever you try to change the topic or pretend you win the graph shows tails with better lift even the article it selfs says it.

    Wing/aft-tail combinations achieve generally lower drag than wing/canard systems of equal weight and area. If the section CLmax is constant over all sections, aft-tail configurations exhibit greater maximum lift capability than canards of moderate aspect ratio. Relaxing static stability results in canard and aft-tail designs with very similar performance

    The differences between aft-tail and canard configurations’ maximum lift capability is again related to the trim constraint. There exists one position of the center of gravity for which each surface carries maximum lift. This optimal static margin is shown in figure 11. Nearly neutral stability is required for canard designs while static instabilities from 0 to 20% are necessary for aft-tail designs.

    you can go around and around but the article says it too

    see what they say too
    The relative importance of these two performance indicies (CLmax and drag) depend on the aircraft’s design mission. A design intended for high speed flight with a strict stalling speed constraint would be strongly affected by the maximum lift capability of the design while the comparisons of relative drag with fixed area applies more directly to an aircraft constrained by climb rate requirements.

    Thus, the optimal design is influenced by the intended mission — especially for canard designs with their greater sensitivity to aspect ratio changes and the large difference between the design with highest CLmax and the design with least drag. A typical compromise might consist of a canard design with equal wing and canard aspect ratios with bt/bw = .5. This design would achieve a CLmax of 72.5% that of an aft tail design with the same wing and tail areas and with bt/bw = .4. The drag of canard and wing would be 107% that of the wing/tail combination.This design would achieve a CLmax of 72.5% that of an aft tail design with the same wing and tail areas and with bt/bw = .4. The drag of canard and wing would be 107% that of the wing/tail combination. Savings in propulsion system integration, fuselage layout, control system simplicity, etc., could conceivably lead one to favor the canard configuration, but in this example the initial aerodynamic compromise is large.

    http://aero.stanford.edu/Reports/MultOp/multop11.gif
    http://aero.stanford.edu/Reports/MultOp/multop.html

    in reply to: Canards and stealth. . . #2388606
    kiwinopal
    Participant

    actually, you have one thing right: “increasing the AoA of a symmetrical airfoil will create downwash”.

    the thing is, on a symmetrical airfoil (like a tail plane or a canard – we’ll talk about one piece canards as they are the ones that interest us in the case of modern fighters), the camber is zero (straight line) – so much about “camber is necessary to generate lift”

    second, a canard (or a tail plane) acts both ways, up and down depending on the needs, so:

    – when they are aligned with the airstream, they generate no lift and no downwash (case with emergency back up in the rafale.. if the FCS has some serious problem, the canards can flow freely and the FCS acts in rduced mode, allowing the aircraft to fly, and land in one piece, if possible

    – when they are activated to generate a force, depending on the way the force is generated, they generate a “downwash” or an “upwash”, depending on the needs of the moment.

    From there on, as they are used for control (pitch, trim, etc…) you can’t just state that they “always generate downwash” or something similar. Just as you can’t just make a single “Cl graph” and say: “here, th’ats what canards do or don’t”.. it’s much more complex than that

    This picture shows you very well the cambered canard the J-10 has
    http://cnair.top81.cn/fighter/J-10_59.jpg
    Having a camber means at 0 AoA you have lift, why you need lift at level flight simply because of stability, adding an extra lift surface ahead of the center of gravity reduces nose up pitch down.
    See the Lavi
    http://img3.photographersdirect.com/img/13717/wm/pd1565395.jpg

    http://upload.wikimedia.org/wikipedia/commons/f/fb/Lavi_wing.jpg
    http://farm4.static.flickr.com/3219/2871488842_42a66dcc2a.jpg?v=0

    from this picture it is obvious it has camber.

    This has trade offs but also advantages.

    You can not only have advantages you always will trade off.

    in reply to: Canards and stealth. . . #2388653
    kiwinopal
    Participant

    Whether or not they have some camber is not the issue.

    The problem is your statement that camber is necessary to generate lift. This is a common mistake due to popular (but incorrect) theories about how lift is generated.

    See http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

    The canards on the Gripen, Lavi and J-10 do have camber, however even a symmetrical airfoil will have downwash, it won`t change that, because As may be expected, symmetric airfoils will have zero lift at zero angle of attack. Thus, a0 is zero for symmetric airfoils. increasing the local AoA of the canard will create a downwash, no matter how symmetrical it is.

    in reply to: Canards and stealth. . . #2388832
    kiwinopal
    Participant

    Kiwi, that’s not cambering.

    Quick google search and here’s an example.
    Symmetric airfoil in the picture is an non-cambered profile.
    There were/are planes flying on symmetrical airfoil.
    How it doesn’t generate lift, then?
    Look Kiwi, we can’t argue about basics and if you really don’t get it, how can you discuss canard’s downwash and it’s influence on the wing, then?

    LOL, Kiwi…if I were you, I’d stop right now, but obviously you’re not even aware of what you’re saying.
    That’s called a “self-assurance derived from ignorance”, but ok…I mean it’s ok to have opinion, but when it’s so wrong and utterly superficial, better keep it to yourself, because you’re “teaching” others, wrong.

    Yeah Cola i think the boot is in another foot, the evidence shows they have camber however there is low camber and there is high camber

    in reply to: Canards and stealth. . . #2388844
    kiwinopal
    Participant

    Kiwi, what does the cambering have to do with the ability to generate lift?
    Cambering only allows a profile to generate a lift at alpha 0°.
    Supersionic aeroprofiles like missile’s wings and fast fighter planes have very little (supercritical) to NONE cambering.
    You don’t loose the ability to generate lift without cambering, but you loose the ability to generate lift at canard’s alpha 0°.
    Those two are very different things!
    C’mon man…these are basics.

    LOL, you must have an 100/100 vision to be able to see that from those pictures.
    Do you know what cambering is?

    Too bad and frankly I don’t overly care…however, I don’t want other posters to create a false image of these concepts, so I’m trying to sort this mess of yours, out.

    i do see cambering it is easily spotable

    see in this picture and i will explain
    http://www.canit.se/~griffon/aviation/img/saab/gripen/gripen_recc-pod.jpg
    The canad has some degree of deflection but if you look at the inlet there is the wing profile of the canard on the wall of the inlet, this print is very easily spotable as a fairing print of the canard wing profile, same is the J-10

    It is not basics Cola, it is simply you are wrong, a canard without lift is plain drag, the canard of course was not a Me-109 wing profile but it has camber.

    in reply to: Canards and stealth. . . #2388873
    kiwinopal
    Participant

    Before you quote a picture to support your opnion, you’d better realized what’s kind of evidence you quoted.
    http://i49.tinypic.com/2d82ohy.jpg
    Notice the higher Cl the smaller span ratio than canard!

    It does not change the fact the tails are getting more lift at their best total lift and the advantage is more evident in the lower ARt/ARw graphs at all aspect ratios that you did not mention

    in reply to: Canards and stealth. . . #2388877
    kiwinopal
    Participant

    No, Kiwi.
    First of all, learn what downwash and upwash are.
    Second, when you learn how does the wing work, you’ll understand that it doesn’t matter if the wing is at 0° or 15° alpha, since it produces lift in the same way and that’s the pressure difference.
    Once the pressure difference becomes sufficiently small the wing stalls.
    So, lower pressure above the wing means air passes over longer route chordwise, meaning it must move faster to “catch up” with high pressure air from below the wing, producing low pressure.
    Now, if you have a canard (or some other body) blowing over the wing, what you essentially do is increase the amount of air passing through the lower pressure zone reducing the pressure even further, thus increasing pressure difference against high pressure zone and therefore INCREASE the lift.

    You don’t get it…Look, first of all, control canards like Rafale’s, Gripen’s etc, are most probably not cambered at all, meaning they have no lift per se, at alpha 0° and therefore no downwash.
    This is why I emphasized difference between Viggen’s lifting and Eurocanard’s control canards.
    So, such non-cambered canards produce lift only during alpha increase and their wake behaves differently than normal cambered profile’s.

    Now, check where the tip vortex from even as low canarded plane as the EF is, blows.
    It blows way over the stagnation point.

    EF doesn’t even have a problem with this, so where should those canards be put to kill the lift?
    Below the wing level?
    Never saw that, except in F16AFTI, but those were way below the wings.

    Ok, slow down…
    Wing twist is something completely else and is used to manage stalling characteristics and is present in all wings beginning in 1930s.

    Not accurate at all.

    If the canard is uncambered them you lose all the stability advantages of a canard you are losing the extra lift ahead of the center of gravity, now you are not even sure if they are cambered or not showing you are just making up an explanation that does not go well with you basic concepts,

    Now having a canard that does not produce lift is just adding drag without any benefit just plain downwash and turbulance

    see this picture the J-10 has a very easily to spot cambered canard
    http://upload.wikimedia.org/wikipedia/commons/thumb/8/86/J-10a_zhas.png/800px-J-10a_zhas.png

    Gripen is the same
    http://upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Saab_JAS_39_Gripen_Canard.jpg/250px-Saab_JAS_39_Gripen_Canard.jpg

    So my friend i do not believe your explanation

    in reply to: Hot Dog PLAAF; News and Photos volume 14 #2388960
    kiwinopal
    Participant

    No there is not but there are plenty of russian sources even in English that say the opposite.
    China was given the design plans for the Russian fighter jet in 1995, when it promised to buy 200 kits and assemble them domestically. After building 100 planes, the Chinese said the Russian plane did not meet specifications, only for a copycat version soon to appear – “Made in China” – without copyright.

    The threat from China is real, and it will be difficult for the Russian aviation industry to maintain its lofty position, and soar further unless it manages to better protect its intellectual rights and also find new ways of co-operating with its eastern neighbor.

    Although it made its maiden flight over 30 years ago, the Su-27 remains the bedrock of the Russian air force, and is highly popular abroad.

    “I don’t think anyone who’s flown on the SU-27 can ask for a different plane, unless we are talking about a new generation jet,” believes Lt. Colonel Andrey Alekseyev, Air Force Pilot. “It’s maneuverable and has a huge range.”

    Some are calling for calm over the controversy. While the similarities between the two planes are clear, experts say the Chinese J11B does not have the latest Russian high-tech features and will be no match for it on the international market.

    The best way to fight copyright violations is to be technologically ahead of your rivals, claims Maksim Pyadushkin from the Center for Analysis of Strategies and Technology. “The biggest problem for Russia is that it has been living off the legacy of the Soviet Union, and soon its technology may no longer be the world leader,” he asserts.

    Rather than a continuing dogfight over the copycat plane, it is possible that Russia and China may yet settle the matter amicably – at the highest political level.

    But in the shady world of international weapons copyright, similar cases are sure to follow

    http://rt.com/Top_News/2010-04-20/russian-arms-copycat-china.html

    in reply to: Canards and stealth. . . #2388970
    kiwinopal
    Participant

    Ok, we have arrived to the source of the problem.
    It really isn’t your fault for being misled by such unclear expression and in short, it’s simply wrong and now I see where does your misconception come from.

    When the canard’s stream blows over the wing it reduces local alpha indeed, BUT by delaying boundary flow separation (energizing), meaning increasing speed of the flow in the low pressure area and thus even more increasing the pressure difference, which increases the wing’s lift, not the other way around.

    Following the logic of alpha/Cl reduction, one may arrive to the conclusion that canard’s stream reduces lift, but this is purely semantic fallacy.

    Otherwise, the document is fairly accurate and handy, since it features many relevant principles and data in one place.

    The documents are right, the only way it will increase lift is at an AoA beyond 5 degree, when canard upwash vortices re-energize the wing upward vortices but at level flight there is an important reduction of wing lift by canard downwash.
    high set canard achieve the best lift but at a higher drag, why? well higher the lift, higher the downwash, this also applies to canard deflections, which increase the lift coefficient of the canard but at the same time its downwash.

    Low set canards will shed their upwash at the bottom of the wing at high AoA therefore reducing lift.

    Some sweptback and forward swept wings use wing twist do reduce downwash effects.

    in reply to: Canards and stealth. . . #2389059
    kiwinopal
    Participant

    this is not the answer i wanted. Your moving away from the subject. the subject was about weaker engine, and energybleed and efficient dynamics.
    And you are still going i circles, with claims without any real facts. just a handfull from one part of the world, stop trolling!

    Why do you think europe, china, and korea see the future in canards but US and Russia dont? Who is really stupid? Whose that doesnt understand or those that see the potential? 😉

    Europe is the only ones that really have experience of the both types (operational). Which way are they going next? It seems to go the canard-way at the moment…
    So once again you loose.

    Using a canard is just a matter of choice depending on the needs of the manufacturer and customer.
    It is not who is smarter of without vision, it is simply how you can cure the drawbacks and fix the cons of each control system.
    You can fix the bad sides of tailplanes and get really good aircraft like the F-22.

    There are many ways to do it, besides each configuration has trade offs, Gripen has it in its STR.
    You can balance that with HMS and new missiles like IRIS-T.
    So it is simply how you solve problems and trade offs of each aircraft configuration.

    In current Su-35BM, MiG-29 and F-16 new missiles, engines, HMS and TVC have made them better than any current eurocanard in some departments.
    So nothing is written on the wall if you use other solutions to the same trouble.

    LERXes and relaxed stability are some applied to tailplanes instead of using canards.

Viewing 15 posts - 181 through 195 (of 472 total)