Cola1973Where it has demostrated the STR on videos posted here? that is not true the Gripen has a lower STR it has been writen in books and webpages,
Here, I mean it’s no big secret…
by the way the Viggen canard has the perfect shape for lift; the eurofighter`s for least drag, the eurofighter high aspect canards reduced wing tip formation and downwash therefore has less drag.
Viggen’s canard is a compromise between lift and wing energizing requirements.
EF’s isn’t and it’s main purpose it to keep trimming forces at the minimum, but not by using a highly cambered profile, like Viggen’s is, but far forward position and long momentum arm.
The Viggen low aspect canard needs a long leading edge to generate powerful vortices…
Finally. 😀
An by the way the TWR of the F-16 is not as high as you suppose barely it is 1.1:1 nothing extraordinary or very high compared to the Gripen which is close to 1.
Yes well, either way Gripen beats F16’s turn, as a result of advanced aerodynamic solutions, which is particularly impressive since F16 has explicitly configured for sustained turning.
Cola1973If you read this you will see the Viggen has a canard ideal for lift, while the Eurofighter for drag
Yes well, that’s essentially what I wrote in my previous post.
However, you can’t compare Viggen’s tabed canard, with EF’s slab foreplane.
Conclusion you get a smaller canard with less powerful vortices, in the Rafale the solution was make this canards as close as possible.
Large canard give you the best lift
LOL, Kiwi, no! 😀
First, there are two types of canards, lifting and control.
Viggen has a lifting canard, while Eurocanards have control.
Second, vortex’ strength is mainly defined by vortex generator’s sweep and roughly, the more swept the generator, the stronger the vortex.
Third, Rafale canard’s vortex energizes the wingtip, unlike LERX’ vortex, so it’s geometry is being made to fit that purpose.
By the way early F-16s have a STR of 21.5 deg/s higher than the Gripen…
Which by the way, isn’t higher than Gripen’s. 😉
Gripen demonstrated that many times over.
Cola1973Wing/aft-tail combinations achieve generally lower drag than wing/canard systems of equal weight and area.
Possibly, but you generally don’t need as large canards as you’d need the elevators, to be, due better position and consequential effectiveness.
Besides, when ditching the elevator, you get to fulfill a wing/elevator gap with more lifting surface. 😉
Delta wing moves 1g Cp further rearward, making canard (like EF’s extreme forward position), the least trim demanding, increasing sustained performance.
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.
LOL yes, but the thing you’re missing here, is that canard doesn’t need as much cambering nor as high thickness/chord ratio to produce required trim force due generally larger momentum against average Cp position and cleaner boundary flow in front of the wing, so it can get away with lesser Cl, meaning higher critical Mach number and less wave drag.
To me the fact the F-22 and T-50 have tailplanes is the product of good yield results in performance and agility.
Frankly, by looking at T50 (and to a lesser degree F22) layout, I can’t help but wonder why not make it delta, when the elevator is already inset into the wing…
If in Europe they have taken the Canard is mostly as a result of size constraign and the lack of real powerful engines.
Finally. 😀
Gripen with 20% or so less thrust, can match/surpass F16’s STR and that’s quite an achievement.
Now, imagine Gripen running around with F110 in it’s a$$.
Russia has now show a new control device the LEVCON which as i said to you has no downwash, this shows there is still new technics to improve agility and keep stealth.
Kiwi, LEVCON is essentially a slat.
How would it have downwash, when it doesn’t have trailing edge??
Cola1973The difference is seconds versus minutes at speed.
True, but that’s beside the point and F22 must ignite the AB to stay on M2, just like F15, so the difference will reduce considerably.
But anyway, the point is F15 is as fast/faster than F22, no matter for how short period of time, or due whatever reasons. Period.
It’s impossible to conduct an articulate conversation, when fundamental factors get skewed, all the time.
Cola1973A Strike Eagle carrying weapons won’t even reach an F-22’s supercruise speed, much less its top speed.
Yes, it would and it does.
How many times it takes for you to start accepting reality?
Cola1973Kiwi, vortex is generated due high pressure (slow) air “spillage” from below stagnation point, to the upper lower pressure zone, thus locally EQUALIZING, or reducing the difference in pressure, killing the lift.
Only once the vortex detaches from high pressure zone and attaches to the low pressure zone, it starts to contribute to lift, so no LERX doesn’t act as a lifting body, but it’s vortex does, but only once it reattaches to the low pressure area.
Cola1973Kiwi, a major plus for the effort and zeal, but you got most of the things here, wrong. 🙂
To make a Canard-tailplane analysis most aerodynamists will do it with canards and tailplanes of the same size, with wings of the same size and the same degree of stability.
No need, because canards due position, don’t need to be as large to successfully performs their task.
The MiG-29 and F-16 have LERXes which basicly add a lifting surface ahead of the wing…
No, they don’t.
They use LERX to energize tail section.
…and have the same function of the canard
No, they don’t, since coupled canards don’t energize tail section, but wing.
, so the LERX is basicly doing the same thing the Gripen`s canard is doing, reducing the supersonic aerodynamic center of shift movement thus reducing trim drag;
No, it doesn’t, because LERX doesn’t add to the lift in the first place.
in the case of the F-16, it has considerable forebody lift and has relaxed stability thus reducing even more trimming needs.
No, it doesn’t, as explained before.
In the case of the MiG-29 its tailplanes are quit far from the center of gravity and have higher swept than the wing reducing trimming needs further.
Irrelevant and I really don’t know why do you insist on this.
well the delta makes for a big wing area with respect the small size it has
What?
Known facts the F-22 has…and a much higher STR and very likely higher ITR
Known facts?!
With the exception of the F-22, F-35 and T-50 most aircraft fight at Mach 0.8 where delta wings offer little agility
What does this mean?
It isn’t a wing that offers agility, but complete aeroconfiguration of the aircraft and Eurocanards repeatedly display superior agility level then current US models.
The so called better ITR of the Eurofighter sounds more like a commercial ploy than a reality, i am sure with max weapons load the Eurofighter has worse performance than a F-22 in ITR because of ist draggy weapons carriage thus negating its supercruising agility at Mach 1.6, at that speed the Eurofighter is at afterburning settings meaning thrust difficulties and the unlikeliness of such statement
Ayayaya…take a look at 5:55 and you’ll see how hollow does this rhetoric of yours, sounds.
EF in film flies with external tank and asymmetric ASRAAM load. 😉
Cola1973Show me please the picture of the F-15 with LEVCONs i know the aircraft but up to know i have never seen it with a LEVCON
No need for some extra pictures…any one will do.
F15’s variable geometry intake when lowered during high alpha maneuvers, reduces the body’s boundary flow alpha, same as LEVCON on T50, thus adding to total lift.
You can insist and call it Cobra but it is not, in order to do the cobra the aircraft has to have a pitch angle of 120 deg and 0 deg at yaw.
By stability we mean 0 deg at yaw because most aircraft will have nose slips at 60 or 70 deg of AoA and this leads to departure.
The Draken is banking and it is not showing a 120 deg at pitch and 0 deg at yaw. Historically the first pilot to have done it was Victor Pugachev.
Not that it matters much but it’s Cobra, all right and an excellent one, if I may add.
The amount of maximal alpha isn’t predefined and is mainly dependent on pitch onset rate, controlled by a pilot or FCS.
Where did you saw loss of directional stability, in this Draken’s Cobra maneuver?
You may want to explore a film some more, since Draken did a prefect Cobra maneuver and with asymmetric flow over the wings (due previous banking) at that, which only testifies of its outstanding directional and lateral stability.
F16, F18 and F22 rely on extensive LERX vortex (and corresponding drag increase) and/or canted verticals, to maintain control authority at high alphas.
It’s interesting to see how canard planes don’t require twin verticals or LERX vortex’ to negotiate high alpha control authority issues.
Cola1973The F-22 is the most advanced western aircraft and perhaps still in the world, the most advanced aircraft in aerodynamics still are Russian and American…
Yea, right…sorry for such an answer, but I’m not sure what else to answer to that.
…the LEVCON was introduced by a Russian aircraft, the triplane configuration on a fighter jet also russian on the Su-33, supercruise was brought by the F-22, the Cobra by the Su-27.
No post stall agility means no fifth generation.
Were are not even mentioning the F-16AFTI and F-15 ACTIVE.
F15 had LEVCON, 40 years ago.
Ok it is called differently, but can do the same job, energize body flow.
F15 generates enough lift for a plane to take off, some 30 or so kts before the elevators are able to lift the nose off the ground, due poor effectiveness at low speeds.
Same with Su33 and the plane got canards for carrier ops, to enhance responsiveness at low speeds.
Cobra is what exactly, apart from FCS and spin recovery “accident”?
Useless PS maneuver that will most likely get a pilot killed in anything but 1 on 1 close combat.
PS agility is essentially defensive “last ditch” action and would probably prove fatal in multi-participant air combat and is completely useless in avoiding missiles.
SC is mainly an engine property and F104 with F119 would SC at M2.9 😀
No advanced aerodynamics in F22, except if you put F22 into stealth category, in which case I agree it’s more advanced than F117.
AFTI is a great plane and it’s strange it never reached front line, in spite of immense advantages it offered in terms of nose pointability, useful for AG deliver, which F16 mainly does today.
F15 ACTIVE (SMTD) is something else and canards were added to counter TV, but the plane was otherwise still a regular F15.
Now, you can see how all those “advantages”, “5th gen must have” and similar, out of context, assertions are mainly pointless arguments.
The F-22 has F-15 ACTIVE ancestry; the T-50, Su-35 ancestry, both designs deleted canards explain why?
Simply you do not need them.
You’ve pointed ancestry well, so why are you surprised if F22 and T50 are conservative in aerodynamic terms?
Neither F15, not Su35 are canard designed fighters, which is obvious and canards on those models have been installed for exploration/testing/special purposes.
Both F22 and T50 got TV to mitigate poor elevator effectiveness, but that doesn’t make them aerodynamically advanced, rather still in the ’70s with added LO features to the airframe.
Cola1973The Cobra is done by a regular Su-27 without thrust vectoring.
Canard deflections will affect further more the wing regarless of AoA.
The Su-35S, Su-33, Su-30MKI, Su-34, Su-37 and S-37 all have tailplanes.
the F-22 does the same post stall maneouvres the Su-37 did but it lacks canards.
Canards are over valued, definitively are good and the Rafale, J-10 or Gripen are good designs but the reality is all configurations have pros and cons and canards might have advantages depending in the needs of the aircraft but tailplanes can get similar results with some aerodynamic configurations.
Cobra is irrelevant, as well.
Any plane can go PS and given enough altitude, will likely recover as well.
F22 does Cobra exclusively due TV. Nothing else.
Sukhois and Migs do it by generating enough pitch onset rate to rotate the plane before stall renders pitch control ineffective.
Canards are canards and there are some things they can do and things they can’t do.
By virtue of being an aerodynamic control body, the don’t, or have very limited usage, in PS maneuvering, just like elevators.
However, as much as US made a progress in LO area, Euro designers did it in terms of flight dynamics, enabling high performance airframes using relatively weak motors (just check Gripen) to match those high powered, but with conventional aerodynamics.
So, once you stick a powerful motor into such an airframe, you can easily outclass conventional airframes, right across the board as Euro designs successfully prove, every time.
F22 (essentially a stealthy F15), didn’t bring anything new to the flight concept pool (except TV) and can therefore be considered backward, in comparison to Eurocanards.
Cola1973Kiwi, the Cp moves whether you want it or not. 🙂
It’s a lift product of the entire wing, expressed as a vector and it “moves” according to current alpha and position of the AC and cambering.
Flight is a dynamic process in terms of Cp/CG relative positions and it permanently changes the value.
This is why, non-FCS steered planes have trimming buttons on the flystick to offset permanent Cp/CG relation change.
It’s difficult to discuss any aerodynamic effectiveness (not efficiency) during PS (Cobra) maneuvers, since both canards and elevators are stalled and the only true control is TV (preferably 3D).
LEVCON in T50 isn’t a LERX and most probably has a function of energizing body’s boundary flow, thus adding lift, when wings stall.
F16 and F18 don’t use LERX for lift but to similarly energize tail section, rudder and elevators and therefore maintain a degree of roll/directional authority, once wings stall and ailerons cease to function.
Cola1973i am not wrong you are wrong, the center of gravity is where an aircraft is balanced longitudinally, that is the reason it is called center of gravity.
Yes, but that is irrelevant, since the plane is balanced between wing’s and canard/elevator’s, LIFT vectors (Cp).
The CG in comparison to Cp position, when the plane is flying 1g, determines the degree of (un)stability.
Now, as the plane starts to increase alpha, Cp moves chord-wise changing the required trim force to keep the plane in required trajectory.
With canarded planes, the Cp is in the most forward position – in AC (aerodynamic center) of the wing (requiring most trim force), when the wing is on it’s best L/D ratio.
With elevatored planes, the situation is reversed and at low and high alphas, aircraft requires more trim than canard plane.
Cola1973An aircraft has its fulcrum on its center of gravity, the moment arm is the relation between the control surface aerodynamic center and the center of gravity.
What does “fulcrum” in this context exactly mean?
By definition tailplanes are farther way from the wings, now canards need to be near the wing so their distace with respect the center of gravity is close.
Irrelevant.
What matters is current distance between Cp of the wing and Cp of the canard/elevator.
In most cases canard wins and even more during maneuver at alphas over ~15°, when Cp shifts rearward, towards the elevator.
It’s only when the Cp is in the AC of the wing, that the momentum arm is the smallest (needs largest trimming force) for canard configuration, but the wing has the best drag/lift characteristic, at that point and so very efficiently mitigates total drag, which is very useful during sustained maneuvering.
You can give relaxed stability to an aircraft with tails and LERXed and you get an aircraft with in pitch up as good o better than Rafale in example T-50 and F-22 .
Correct me, if I’m wrong, but I’m not sure whether you know, why planes have LERX.
You’re mixing some things here, hence my conclusion, but I could be wrong…
Cola1973Even the stealthy Gripen had its canards above the wing affecting in general its LO, tailplanes always are benefited by the downwash of the main wing and can always have a better moment arm.
Having downwash aeroprofile (wing) in line and in front of another (elevator), actually reduces elevator effectiveness, until elevator’s upper surface gets into the wing’s downwash stream.
And no, again.
Canards and wing by virtue of their Cp and AC positions, usually have larger momentum arm. This is one of the reasons, why canards are generally smaller, since required trim forces are smaller.
Cola1973Does this mean that the IRST can do everything an FCR can except allow for firing solutions?
Well, according to public data, PIRATE (didn’t find for OSF, but I’d assume it works in the similar way) has all the searching/tracking modes, of the radar.
Plane’s FCC module that calculates intercept vectors for all inputs regardless of origin sensor can allow a launch against passively (IR) tracked target, once targets range is approximated, accurately enough.
I am assuming of course, that its detection ranges are not as high as radar for non-AB targets especially.
For PIRATE it’s stated 80nm extreme, while normal being 30-50nm, but it doesn’t say against what type of target.
Those ranges seem to correlate with Meteor range/requirements.
Didn’t find any data on OSF, though.
Would really be interesting though to find out at what ranges an uber IRST can detect a supercruising bird at high altitude.
The airframe gets pretty hot it seems and stands out quite nicely against the cold atmosphere.
Yes well, that’s the problem and a plane cruising at 40k ft, at M1.5 has a difference between stagnation and ambient temperature of about 150°C.
That’s an enormous delta in temperature, producing a strong contrast visible from very far away, especially for sensors as sensitive as are those in modern IRSTs and the only (un)fortunate thing is that IRSTs can’t measure distance, requiring certain flying patterns to try to measure a distance, or another linked sensor.
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