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Old Dec 21, 2012, 12:35 PM
Flying Hazard
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Never got to bring down a single yellow Su... they were so badass!
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Old Dec 21, 2012, 02:08 PM
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Originally Posted by SU-4ever View Post
Only the prototype version of the Su-35 had canards.

The production series had the canards and airbrake removed.

That's why I'm starving so badly for a SU-30 MKM or MKII with canards and bi-seater, wich is actually more beautiful!
They managed to improve the airframe enough to get rid of the canards. Plus adding TV makes canards obsolete anyway.
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Old Dec 21, 2012, 02:33 PM
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Well not exactly! LO or low observability is what primarily drives that. It cost them a lot more to redevelop exotic materials to lighten that section.

But the canards function of flow control is useful enough that they were integrated into the PakFa T-50 on the LERX.

The step is costly because the variable mechanism adds a weight penalty such that even variable duct inlets are becoming a thing of the past. In spite of the penalty they still added this variable root extension to prevent stalled air at the root as they still anticipate dog fights at higher energies with potentially Euros, F-22s and may be China variants.

Looking at the rudder and ray dome tail of the Yellow 13, the canards aren't supposed to have positive pitch... but then again its just a game.
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Old Dec 21, 2012, 03:35 PM
Flying Hazard
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Agree with Max.

And heck! they are so beautiful...
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Old Dec 22, 2012, 01:29 AM
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The canards had nothing to do with airflow into the intakes - they were not even in line with them.
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Old Dec 22, 2012, 02:03 AM
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Huh? Did someone say the canards had something to do with airflow into the duct inlets?
I didn't see that mentioned anywhere.
Unless you mean Max's "Flow control" part... but that is to do with controlling airflow over and under the wings, not flow into any duct inlet.

Though I would expect they do a 'dual function'.... more used as an 'elevator', for pitch control, than control air flow over the wings - which would be a very strong input factor being where they are. But it also means the combination of canard angles, and elevator angles, can form some 'radical' results when they work in unison, or at other times oppose. That would be up to what FBW programming they did to use them in whatever manners they found useful.
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Old Dec 22, 2012, 08:49 AM
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No Pete, you are wrong. They are used for airflow control pretty much alone just as Max said. Pitch control role for them is marginal.

You can't get higher SUSTAINED turn rates if your wing has already stalled, that's one of the reasons. Tailerons and TV already give more than enough pitch authority.

On the Eurofighter and rafale they may have more pitch role mixed with airflow control.

About the flow into the inlets, I think Max was speaking of the T-50.
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Old Dec 22, 2012, 09:38 AM
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But if you are flying along at speed X (lower speeds not high speeds) and then use a canard, it is going to cause dramatic pitch! Irrespective of wing stalling situations etc.
You were flying along fine, and got a huge pitch input... and from the front of the aircraft is different than from the rear. The pitching process will be different for both ends - ending up much the same result, but not initially. So a canard can give its own unique pitching abilities.
The huge angles they can move to - seen in flight pics and videos - just show how much input they would have to the equation!

I would consider the 'airflow for the wing' factor is just a sub-set of their true usefulness. Use them in small doses and they can be used for flow control.. but use them in larger angles and it is all pitch. So IF they only moved, say, 10deg max ever then you could expect it was only for flow control purposes.
Though I guess that large angles, at very low airspeeds, could be flow control uses mainly, instead oif pitch uses. (but would still have the spin off effects of affecting pitch too).

A taileron or TV cannot match what a canard can supply. Pitch control from the FRONT AS WELL means a lot more manoueverability possibilities are available. Even if only for fancy 'airshow antics'.
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Old Dec 22, 2012, 09:57 AM
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Thinking about it... I can see a 'chicken and egg' situation.
It will depend on HOW and WHEN you use the canard, as to what its main result will be. Pitch or flow control.
You would need to watch the aircaft's motions, and the canard motions, in unison, to see what they were being used for. A canard could be at 30deg, but the aircraft's attitude was also 20deg, plus the canard would be in 'opposite' direction to the pitch result... showing the 'egg came before the chicken' (LOL)... that the canard did not supply pitch, but at least NOW was being used for flow control. And seeing the initial aircraft move to 20deg, from level, should show what the canard did THEN..... quite possibly "chicken before the egg' this time, if it moved to up initially, to (help) instigate the pitch change, before moving to the downwards angle seen later for flow control.

Plus, even the airspeeds involved play a part.. because it if went to a slow flying 20deg - rather than a fast flying speed that would then make the path pitch increase cause a curving climb - then the slow flying 20deg attitude would show it needs some airflow control (to raise the stall speed), whereas the fast flying one would possibly show (if it moved the appropriate direction) that airflow control is not needed in that situation and it was all pitch use.

I think I recall seeing landing videos, and the aircraft attitude is positive - maybe 20deg sort of thing - and the canards were downwards, at maybe 25deg to 30deg, and 'fluttering' as they were controlled for their purpose. In that set of parameters, I would expect it was for flow control - because having them down means pitch down, but the aircraft is pitched up, thus they would have been used to feed air up and over the wings in that case I expect.

They might not even be strong enough to ever allow control of them for pitch use. Even though they can go to large angles (looks like 45 deg) it is usually a low angle to the airflow, even if the canard angle itself is large.
Though I think I also have seen them landing and using the max canard angle downwards, after touchdown, thus a large angle to the airflow then, and probably used for their drag and resultant air-braking.
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Old Dec 22, 2012, 10:07 AM
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Fred I was reasoning on the weight penalty of a variable inlet as being costly enough both in weight, LO and maintenance, that most seek fixed inlets. This describes that though variable anything has penalty, they still added a variable LERX on the T-50 to take on the same function as the canards previously did.

So the removal of the canards wasn't that they were made redundant, in response to Sockrat, but that they were too costly with low observability. Removing their extra weight, using lighter alloys physically improved things, but they are not up against a tougher customer, the F-22. So they have a combination tactic to expose the F-22 to vulnerability.
Anyways;

The T-50 variable LERX to my knowledge doesn't have a roll in the air flow to the intake but to the top of the root flow as it did with most of the Canard variants and even the Euro.

LO wasn't a primary tactic in gen 4 aircraft. The Euro new radar and long range missile suite changed this and SU wanted to reduce the signature and weight that the Canards and LERX had with the early SU-35. They realized in a 4++, removing the canards and changing the weight distribution with materials/alloys, while using FCS software and TV, they could make marked improvements against most 4++ aircraft.
But Gen 5, specifically the raptor they felt tactics can force a merges to expos them into close in missile dog fighting within detection range; even low K ban arrays. In such, while the F-22 is very maneuverable, it can be out flown by even the Euro in close quarters. Thus the T-50 employs LO Variable LERX to assist the maneuverability in the transonic even with such a weight penalty. This shows the original canards were never really obsolete, they just didn't have a good solution to employ them at the time.

Canards is one of the things that makes the Euro maneuverable where in the transonic they too primarily point only down to assist with flow. The FCS does still use them as a pitch control device as well depending on conditions. Canards used this way also have another function in changing the G load to the pilot. The aircraft tends to rotate around the pilot reducing G load to the pilot in hard pitches. They just show up on radar too easily to there newer counter parts.

Speculation though has not yet explained if the very slight positive pitch (above center line) on the T-50s new variable LERX is for inlet, air flow or maneuver, since its not clear if or when its deployed dynamically. Only that it has been photographed to during ground run ups as moving above datum.

So no, never meant to imply the variable LERX were for inlet flow, but as flow canards they were useful enough to redeploy in a LO design in spite of their weight penalty and the T-50 still having TV, Ruddervators and even better FCS suite.
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Old Dec 22, 2012, 10:44 AM
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Pete you're indirectly correct
You said earlier they made a million variants. They have also tried using the Canards in a number of ways on the various versions.
It appears though that they have the FCS settle on having the canards pitch only down as an airflow device. On most models they are actually slaved to the LE wing flaps. On some they have some independence from the wing LE.

Too, while the canards can have a pitch influences since, let's face it even the tiny canards on the B1-B a used to contorl low fast map of the earth flying, they can be very effective, but they don't need to be.

The findings are if you can move any combination available to perform a maneuver at what ever given speed with the lowest observable signature, which also is the lowest drag, that is what the FCS selects.

Since tailerons and TV have less drag and because they can not slap on fences, strakes etc because of LO, they mainly have the canards there for flow function.

Between the Terminator 37, 33, 35, 32, 34 etc they had various rudders and tail raydomes along with canards that becomes a signature of how the canards may have been deployed/used at that time in the program.

But I though genius when they just took the canards and butt it up against the LERX on the T-50 to remove any seams but maintain their primary function of flow control as the original canards did.
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Old Dec 23, 2012, 07:04 AM
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I would have thought if they used earleir ones just for flow control then they would of course run them right to the LE. Having a 'gap' would be ineffiecient.
But not so 'inefficient' for use as a pitch device because then you do want separation from the wing, to allow airflow 'smoothness' to resume (or at least have time to improve the most it can).
However, they did set them quite close.... maybe some technical reason does come into play that it works well with a gap like that (for flow control).... or, they just could not do the mechanics further forwards anyway (probably likely).

Then you have that T-50 example of them very close to LE.... so they either learnt more.... or the originals were not even aim at just flow control (but surely aerodynamics engineers knew enough already long ago about all this - seeing there have been numerous jets with canards before).

Plus then throw in the FCS being programmable, so they can test all kinds of things to see what works on that exact plane version, after it is all built and has the control surfaces wherever. Then they would find out "Hmmm, that doesn't do as hoped. This does work well for this purpose. Hmmm, it foes this better than that what it was intended for. This is not so great and not worth the cost and weight etc of the implemantation." etc etc
(They can add what they learnt into the data base for future aircraft ideas! lol)
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Old Dec 23, 2012, 08:17 AM
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Turkey Day?! Ah, Oh...
A Slat is to this kind of canard as a drooped LE flap is to the variable LERX.
Because there is air flow between the Slat and the wing it operates more efficiently. The canard functioned the same way.
Canards in this manner are also used as a trim device.
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Last edited by Maxthrottle; Dec 24, 2012 at 12:45 AM. Reason: drooped not dropped
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Old Dec 23, 2012, 11:55 PM
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They had "Canards in the manor"? What did the butler think about that? lol
(But was the error in the 'Canarys' or the 'manner'? hehe).
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Old Dec 24, 2012, 12:38 AM
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Originally Posted by PeterVRC View Post
They had "Canards in the manor"? What did the butler think about that? lol
(But was the error in the 'Canarys' or the 'manner'? hehe).
Thanks for the spell check Pete. But don't stop there. I posted many times in this thread. Can you spell check all them also.
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