I think I understand now. So in a canard delta aircraft the canards control pitch in a turn and in a pure delta aircraft the rear control surfaces take the place of the horizontal stabiliators?
J-20... The New Generation Fighter III
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I think I understand now. So in a canard delta aircraft the canards control pitch in a turn and in a pure delta aircraft the rear control surfaces take the place of the horizontal stabiliators?
two concept in flight mechanics.
1. Nose pointing, or how your physical nose point relative to an inertial frame ( earth). how high your nose is below or above horizon for example.
2. where the airplane is going, which is where your airplane's velocity vector is pointing. or the flight path angle. the angle between where the airplane is Going relative to an inertial frame ( earth).
now, turn, what is it? it is simply the change in flight path vector / more specifically, flight path angle.
so, how do one change flight path angle.
how does one change velocity vector espcially its angular component? by apply acceleration ofcourse. just like in any object.
more specfically, applying acceleration perpendicular to its velocity vector.
Lift, just happens to be perpendicular to the airpalne's velocity vector.
So, a turn is nothing but changing the airplane's velocity vector.
you do that by using lift, which is perpendicular to your airplane's velocity vector.
So,
to change #2, one has to change #1.
why? #1 yank the airplane nose higher temporarily so that a high aoa is achieved higher aoa (*aoa, angle between velocity vector and physical airplane) usually = higher lift
how do one change #1?
your use a pitching moment device, which is either elevator, elevarons or canard.
elavons is not necesary on a non-tailless configuration.
leading edge slats are not necessarily, it is just but a tool to extend the point where no more additional lift can be generated by going to a higher alpha.
Well, that'd be what my common sense or instinct tells me, too. And that's why I feel the canards should deflect the air in order to lift the nose. Since with J-20, the canards are doing the opposite (I do understand or remember i.e.'s explanation), what's the thing the pilot pulls back to maintain the angle of attack?
Because in a turn, the wing is generating less lift(part of the lift is channel to centrifugal) as compare to flying straight and level. Hence the nose will tend to drop if the pilot does nothing to correct. To maintain the same flight altitude in a turn, the pilot needs to pull the control in order to prevent the nose from dropping. This resulted in greater AOA and lower airspeed. The steeper the turn, the more he needs to pull.
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Hehe, I think you took my "what" for "why." I understood what you said but was asking you what control surfaces he's pulling in order to prevent the nose from dropping? We saw the photos that the canards were doing the opposit for the purpose that i.e. says. And I don't recall seeing other control surfaces doing much during a turn to lift the nose...
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Elevator. In J20, it the canard. the photos appear kinda weird to me. It should be deflected upward instead.
See the way the canard was deflected in Rafale to lift the nose up during landing.
[video=youtube;BDBWaq1rnPU]http://www.youtube.com/watch?v=BDBWaq1rnPU[/video]
Elevator. In J20, it the canard. the photos appear kinda weird to me. It should be deflected upward instead.
See the way the canard was deflected in Rafale to lift the nose up during landing.
[video=youtube;BDBWaq1rnPU]http://www.youtube.com/watch?v=BDBWaq1rnPU[/video]
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Quickie
Colonel
Which J-20 video/picture you're referring to? The J-20 always has its canards deflected upward and its tail stabilizers in an intoe position during landing.
Slats are airfoils, most often retractable, in front of the wing leading edge on subsonic aircraft to help airflow to keep attached to the upper surface of the wing. Wings for supersonic aircraft are too thin to use slats. They use leading edge flaps.
MiG-29
Banned Idiot
this is the answer:
All this is, again, fighter classics for
the delta winged aircraft with foreplanes.
And here lies their limitation: the pilot cannot
move the trailing edge further down,
since the resulting lift force that builds up
on the training edge will be hard to balance
with the canards,
in my opinion this analysis nailed the aerodynamics of J-20, it predicted high canard deflection on turns
But the Chinese airplane appears to
have the center of gravity position somewhere
at MAC’s edge. It is fairly strange
for a maneuverable fighter, since balancing
of the aerodynamic forces and
the gravity will require relatively high deflection
of the control surfaces — canards
in the J-20’s case.
you can not say it is bias because actually it praises Chengdu
Why the Chinese shaped the J-20
in the way it is? Perhaps, they are unfamiliar
with the classic solutions for a delta-
winged, canard-equipped fighter? No,
this is not the case knowing that Chengdu’s
previous design was the J-10 light weight
fighter, now in service with PLAAF. On its
first public flight, the J-20 was escorted by
a J-10B twin seater, the operational trainer
version of the baseline J-10 single seat
fighter. This airplane was the star of the Airshow
China 2008 and 2010, when it flew
superbly with the PLAAF display team pilots
at the controls. The J-10 is a very maneuverable
airplane, and this is the testimony
of the Chinese designers’ skills in development
of maneuverable fighter aircraft
In my personal opinion they are right on the money about on the role of J-20, TVC nozzles might improve the J-20 to the level of perhaps achieve F-22 agility, because i know F-22 expands a lot its AoA with TVC nozzles
see figure 9-15. Role rate performance, showing the effect of thrust vectoring. (Courtesy of LMAS)
and see Figure 5: Maximum pitch up, pitch down of the YF-22 aircraft compared with F-16 [6].
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didn't we have a thread for these Mig-29 spurred aerodynamic discussions spanning pages and pages? Can a mod please move the relevant posts into a different thread plox, leave this one clutter free for actual J-20 developments, pics and news...
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