J-20... The New Generation Fighter III

[paintgun]

thanks!
now if someone can explain the canard action, or it's just trim and counter pitch like been said

wolfie's Typhoon pic is a good comparison

 

[siegecrossbow]

AFAIK, trailing edge is rarely changed during manouvers, except for pure deltas which don't have any other options, because it screws up the lift. That is precisely why pure deltas have fairly bad sustained turn rates - because their lift keeps dropping during the turn as their control surfaces screw up the airflow over the wing. delta canards and conventional layout planes don't need to do that.

What about aircraft like the F-15 that doesn't have leading edge control surfaces?

 

[escobar]

from the recent flight

 

[MiG-29]

What about aircraft like the F-15 that doesn't have leading edge control surfaces?

No it does not, the F-15 was design as a high thrust to weight ratio and low wing loading fighter, there are parts of the flight envelop where the F-15 surpasses MiG-29 and Su-27 specially in the transonic area around Mach 0.9-1.1

 

[siegecrossbow]

No it does not, the F-15 was design as a high thrust to weight loading low wing loading fighter, there are parts of the flight envelop where the F-15 surpasses MiG-29 and Su-27 specially in the transonic area around Mach 0.9-1.1

I meant to ask how the F-15 turns when it doesn't have leading edge control surfaces. Does it use the horizontal stabilizers instead?

 

[i.e.]

What about aircraft like the F-15 that doesn't have leading edge control surfaces?

leading edge devices only provides higher stall alpha, doesn't provide a high lift at a given alpha. nor does it provide the pitching moment.

trailing edge elevarons (elevator-and-aileron) on a pure delta provides pitching moment by dumping lift at outer edge of the large delta, which happens to change pitching moment. because out board lift dump moved the total center of pressure fwd.

anyways all of you are wrong


as for using elevarons AND canard. dassault rafale uses it but not the main pitching control, partly because its canard are sized pretty... conservatively. for a large canard aircraft like J-10/20/Typhoon/Gripen there is really no need to use for pitch because the canard is big enough. but some do uses it for one reason or the other (Gripen for example...as the famous and widely published Pilot-induced-oscillation or PIO event shows the inner workings of Gripen's control law. anyways, way beyond the realms of amature forum boys but into the realm of pros )




by itself the 1st order function of canard is nothing but a fwd pitch moment device...just like a elevator but fwd of cg.

---------- Post added at 09:23 PM ---------- Previous post was at 09:18 PM ----------

the maximum lift config would probably look like this (take off and landing config) :



same like siege, also wonder what the trailing edge is (not) doing
can't get my head around this picture, the more i look at it the more confusing

The 2nd picture is a momentary picture.

could simply be that...
The pilot could be pulling back on the stick to ask for more alphas(Gs) but Flight COntrol System is deflecting the canard surface down to arrest the extra pitch rate so the airplane don't overshoot its maximum alpha and stall.

all in day's of work of a full authority flight control law.

 

[Engineer]

One thing I don't understand is why they aren't using the rear control surfaces to do anything during a turn.

Aerodynamics is referenced to the air stream, not the ground. In a turn like the one shown in the pictures, AoA remains constant so elevator deflection isn't necessary.

The canards are actually maintaining a zero incidence with respect to the incoming air, so as not to produce pitch moment thus maintain AoA as constant. They are not forcing the nose down. Judging by the angle between them and the airframe, it would appear that the aircraft was flying with a 40 degree AoA.

 

[Air Force Brat]

No it does not, the F-15 was design as a high thrust to weight loading low wing loading fighter, there are parts of the flight envelop where the F-15 surpasses MiG-29 and Su-27 specially in the transonic area around Mach 0.9-1.1

Quite right my boy, and lots of USAF throttle jockies who are qualified and offered the F-22, stayed with the F-15. Because the F-15 is a pure A2A platform, trailing edge, leading edge, canards, the F-15 is a pilots airplane designed by and for Pilots, much safer than the F-16, twin engines with plenty of thrust, lots of wing to fly around, lots of stabilator and rudder. Aerodynamically straightforward, and good avionics suite, and weapons. A Fighter with a capital F. Now I am a Flanker Fan, but I loved the Mig 29 first, Raptor had to grow on me, I "LOVE" Pak-Fa, and the J-20 is winning me over, poor little F-35, I am suggesting the Arkansas Razorback as her nickname, but she aint even in this horse race. I will always have a deep and abiding affection for the F-15. The F-15 does have landing flaps, and a big speed brake behind the cockpit, but you fight it clean, but....... if my bacon was on the line, no contest, no emotion, no prejudice internationally against any one of these birds, but when you absolutely, positively want to come home theirs only one........I typed it but I won't say it, they are all beautifull flying art. They each have their strengths.....and weaknesses. PM me if you want to know the one, as I stated they are all brilliant.

 

[latenlazy]

leading edge devices only provides higher stall alpha, doesn't provide a high lift at a given alpha. nor does it provide the pitching moment.

trailing edge elevarons (elevator-and-aileron) on a pure delta provides pitching moment by dumping lift at outer edge of the large delta, which happens to change pitching moment. because out board lift dump moved the total center of pressure fwd.

anyways all of you are wrong


as for using elevarons AND canard. dassault rafale uses it but not the main pitching control, partly because its canard are sized pretty... conservatively. for a large canard aircraft like J-10/20/Typhoon/Gripen there is really no need to use for pitch because the canard is big enough. but some do uses it for one reason or the other (Gripen for example...as the famous and widely published Pilot-induced-oscillation or PIO event shows the inner workings of Gripen's control law. anyways, way beyond the realms of amature forum boys but into the realm of pros )




by itself the 1st order function of canard is nothing but a fwd pitch moment device...just like a elevator but fwd of cg.

---------- Post added at 09:23 PM ---------- Previous post was at 09:18 PM ----------



The 2nd picture is a momentary picture.

could simply be that...
The pilot could be pulling back on the stick to ask for more alphas(Gs) but Flight COntrol System is deflecting the canard surface down to arrest the extra pitch rate so the airplane don't overshoot its maximum alpha and stall.

all in day's of work of a full authority flight control law.

So what's making the plane execute the turn then?

 

[Air Force Brat]

I meant to ask how the F-15 turns when it doesn't have leading edge control surfaces. Does it use the horizontal stabilizers instead?

Seige, leading edge devices are a passive device that increases the camber of the wing, they may be manually deployed, flight control system deployed or as they were in the early days employed by aerodynamic loads. For example, with the aircraft on the ground the leading edge extensions would be fully deployed, during the takeoff roll and in the low speed regime they remained deployed until increasing airspeed increased pressure on the leading edge and pushes them into their low drag, fully retracted position, where they were flush and smoothed out high speed airflow. In high angle of attack manuever they would deploy as needed to increase lift in the low speed or high aoa condition. They are not a pitch control surface, per se and yes the F-15s pitch is controlled by stabilators, once again if memory serves me correctly the max aoa of the F-15 is around 35 degrees. If I'm wrong we will both hear about it.