Not my task to teach you the basics and I have no idea you got your funny things from.
No it is your task to LEARN them instead of having thew arrogance of pretending you KNOW them. :rolleyes:
Basics are as i posted. 😉 Have a good read.
Every fighter has a safety ratio of 1,5 or at least 1,4 before suffering something critical. G-load has nothing to do with lift at first. Twisting again?!
WHOT?:confused:
So according to you, you can achieve the same g load with LESS lift?
This is that funniest thing i have read for a long long time.:D
You NEED high LIFT coefiscient to be able to pull g and you need high structural load as well, but also low wingload and high air density.
I think you mystake ME for your friends 😎
And maybe there are some more bad news for F-35 after all…
A look at Handling Qualities of Canard Configurations
Seth B. Anderson: Oct 1986.
Langley Reseach Center Library, NASA, Hampton,Virginia.
I think c’est les USA. 😎
Last find from this author…
http://naca.central.cranfield.ac.uk/reports/1951/naca-rm-a51b28.pdf
Management
Dr. Eugene L. Tu
Director
Aug 1996
Numerical Study of Steady and Unsteady Canard-Wing Body Aerodynamics:
Numerical Study of Steady and Unsteady Canard-Wing-Body Aerodynamics_19960047050_1996071178 PDF
Dr. Eugene Tu became Director of the Exploration Technology Directorate in 2005. Dr. Tu joined NASA in 1984. Prior to becoming the Director of the Exploration Technology Directorate, Dr. Tu was CICT Program Manager. He has served NASA as a research scientist and in several management positions. Dr. Tu received his education at U.C. Berkeley (B.S. in Mechanical Engineering) and Stanford University (M.S. and Ph.D. in Aeronautics and Astronautics) and was awarded an Outstanding Leadership Medal by NASA in 2000.
http://infotech.arc.nasa.gov/management.php 😎
😎
Dare2. You got me running through of PDFs, for nothing…
In all docs you sent (and others, that I found), there isn’t a single word relating specifically to close coupled canard layout, whatsoever, only with/without canard comparisons, have been made.
So, let’s see.
Once Rafale goes supersonic its Cp shifts so much back that the aircraft needs either elevon or canard pitch up trimming momentum, to keep nose up (this happens due physical wing cambering).
Well, actually this is the case of Typhoon ad documented by an interview dated from 2000 on the benefits of TVC.
Daniel Ikaza, ITP project manager – nozzles, says Dasa’s study shows that a Eurofighter flying at 30,000ft (9,150m) and a speed of M1.8 requires a 4° upward flaperon deflection to maintain level flight. A 5° upward nozzle deflection instead would enable the aircraft to fly “clean” and reduce the required engine thrust by 3%.
DATE:23/05/00
SOURCE:Flight International
EJ200 thrust vectoring backedhttp://www.flightglobal.com/articles/2000/05/23/66017/ej200-thrust-vectoring-backed.html#FIPageTop
When using canards, as forward trimming (lift) point, the lift vector product (Cp) moves a bit forward in proportion with canard lift contribution to overall lift and therefore comes closer to CG, making aircraft less stable.
The real effect of close coupled canard is foremost to help the apearence of vortex lift on a delta wing at much reduced AoA, therefore resulting in a much cleaner airflow and lower induced drag as AoA can be reducedfor the same amount of lift.
Here are the polars for the Mirage IIIS and te comments of the flight-test pilot, Source i9s Flight International 14th December 1985 Edition (Archives).
http://i588.photobucket.com/albums/ss325/aviadare2/CanardEffects.jpg
http://i588.photobucket.com/albums/ss325/aviadare2/Shift.jpg
I think it is clear that the smaller canards of the IIIS resulted by a shift forward of the cg/cl neutral point, meaning it made the aircraft less stable with a marked nose-up moment.
This is is what dynamic instability is.
However, this still doesn’t mean that the aircraft is unstable, just less stable.
With good computation the resultant cp is enough to get the aircraft neutral or close to it in supersonic, in subsonic, with close coupled canards it will MORE instable than with its %age of static instability alone.
Such Cp movement then destabilizes aircraft and counter trim is required.
Actually NO.
At subsonic flight regime, the aircraft is more instable the dynamic instability added to the static instability only means it can be trimed down, it dosn’t mean it increased trime drag if the design is well sorted, it won’t need it.
This can soon turn into oscillations and so damping software is required to mitigate this characteristic.
Not in the case of close coupled canard, DAMPING levels are higher.
Few points.
Such dynamically unstable layout doesn’t require close coupled canards, at all. Any momentum generating point capable of generating positive and negative lift, in front of wing’s Cp, will suffice (EF, Gripen, J10, etc…).
During such dynamic instability, the aircraft requires trim and therefore its induced drag is increased.
Again it depends on the design.
So, “dynamic instability” is, in fact a normal trimming method for canard aircraft and is by no means Rafale’s specific.
WRONG: It is the result of the close coupled canard configuration.
Tailed RSS (nonVC) aircraft like F16, use the same method, only on the different side of the wing, which makes them more stable, as opposed to less stable in canard case.
No it wont. In subsonic the f-16 doesn’t have to trim down, the elevator have a designed amout of lift to counter the nose-up moment, it is a liofting surface then.
In supersonic things changes, theaircraft needs to be trimmedto counter the pitch-down moment, a close coupled canard still will retain dynamic lift.
Note on EF.
EF will not beneficiate from dynamioc lift at any mach, subsonic, transonic, supersonic.
EF has -4° elevon trim because of variable cambering (VC) setting supersonic requirement. Check F16’s wing VC for supersonic flight speeds and you’ll see it has flaperon set to -2°.
NO: EF have -4° elevon trim because the cp has shifted behind the cg.
This is because at supersonic speeds, the wing needs the most supercritical profile as it can get and that means the least curved upper surface of the wing and that means both slat and trailing edge negative trim.
I desagree, this is because whatever your wing profile, thicknes ratio, aspect ratio, your cp will SHIFT backward, try the basics with the Edward AFB test-pilot explaining it very clearly.
Well 1999 was not the time the design choices were made and it certainly is an afterwards report, like many others and by that not necessarily more accurate.
Had you read it you would have figured it couldn’t have been more accurate considering the source of the interview (development phase director Martin Friemer). :p
The Eurofighter programme moved into the production phase at that time and the first two export campaigns (Norway & Greece) were running by that time.
It doesn’t change anything to the accuracy of the comment made.
An important point to take into account is that the canard position was low forward from the very beginning, starting with MBBs first delta/canard TKF90 proposal presented in april 1978.
It depends which design you are mentioning, clearly BAE had other ideas as did Herbst at early stages of the TFK-90 design history.
A chin intake was one of the key configuration features of the Eurofighter (and the TKF before it), selected because it offered performance advantages at high angles of attack and sideslip. As a foreplane located close to the wing produced too much supersonic drag when combined with a chin inlet, designers selected a long-coupled delta/canard configuration.
DATE:16/06/99
SOURCE:Flight InternationalComing together
http://www.flightglobal.com/articles/1999/06/16/52567/coming-together.html#FIPageTop
The fact that the distance between the canards and wings was shorter up to the EAP in conmparison to the Typhoon is owed to the fact that the wings were stretched much farther.
This is actually untrue:
BAE P110 clearly wasn’t a long moment arm conceipt as for Herbst TFK-90 it also saw the distance between the canard and wing increase as time passed for the reasons explained in the above article (See pitcures provided).
The reason was the aerodynamic interference between the canards and inlets and then some more unwanted effects.
The initial wing design of the TKF90 was “longer” due its much steeper sweep angle, but had a shorter span.
TFK-90 wing shapes changed several time over but the reason for the decouplage of the canards had nothing to do with this (See pitcures provided).
Following wind tunnel tests a cranked delta was found to provide a general improvement over the initial highly sweept plain straight delta and was subsequently adopted for all following design concepts ranging from ECF over ACA up to the EAP
Then again a blatant innacuracy, everyone was looking at improving maneuvering characteristics at lower speeds while retaining the low drag ratio of the steeper swept wing.
Even Dassault ACX and Rafale A were so designed, infortunately the difference in cp shift between the two part of the wing made overal good control quiet difficult, the cranked configuration was responsible for an unwanted level of lateral instability, there was no real gain in this solution, so everyone went back to the straight swept leading edge.
The long moment arm is given by the relation of canard position and CG, not the point were the wing root starts.
The definition of coulped canard doesn’t change when canard vortexes and wing cortexes interects in such a way as to increase lift significantly the surfaces are said coupled.
The term long moment harm reffers to a mechanical solution NOT an aerodynamic one.
That means the concept of how the canards should work was at anytime the same up to the Eurofighter or in other words the long moment arm was ever there at any given time since the very first TKF90 delta/canard proposal from MBB.
WRONG. 1984 design of TFK-90 are clearly NOT decoupled.
http://www.flightglobal.com/pdfarchive/view/1984/1984%20-%200876.html?search=MBB TFK-90
http://www.flightglobal.com/pdfarchive/view/1984/1984%20-%200878.html?search=MBB TFK-90
Scorpion: It would be very nice if you were to stop inventing stuff, standards, definitions, history etc.
Desinforming the members of this forum isn’t a very honnest thing to do, everyone have the right to read things as they are in real life, not the distorted version you find convenient to post because it might look better. Cheers:cool:.
This one shoes yet another problem with the vertical position of the canards for this configuration.
At 0* AoA with canard deflection (on the left scale) the airflow over the wing became unsteady with a significant loss of lift before canard maximum deflection was reached.
This is one of the reasons why their positon in both axis is to important.
Diverse German configuration including that of Dornier and TFK-90, note the close-coupled canard…
BAE P-110
TFK-90
TFK-90
As a foreplane located close to the wing produced too much supersonic drag when combined with a chin inlet, designers selected a long-coupled delta/canard configuration.
The reason why the 8% was chosen was due to the FCS being only able to handle that amount of instability, they certainly wanted more instability than 8% IIRC ~15% was desirable but the FCS/Canard combo couldn’t do it within the drag/speed constraints.
I know that, Jwcook and it is a very interesting design point indeed, but there are other, non-quoted reasons which the press of the time highlighted.
Eurofighter designers wanted as much instability as possible, for minimum drag and maximum agility. “We aimed for 15% early on, but settled for 8%,” says Friemer.
The maximum pitch instability possible was determined by the capability of the flight controls. “We needed highly dynamic actuators, which drove the level of instability we could achieve,” he says.
DATE:16/06/99
SOURCE:Flight International
Agile thinking
http://www.flightglobal.com/articles/1999/06/16/52589/agile-thinking.html#FIPageTop
When i try to figure an aircraft capabilties, i generaly start by looking at archives.
F-I is full of good old infos, very useful and generaly released before censure or PR takes over the programe managers freedom of speech, this one is quiet interesting and it also demonstrate the limits of the technologies of the time (Actuators).
hmm… Don’t the studies indicate that the reverse was true.. :-
It depends who is publishing the studies, if you read Dassault, SAAB or even NASA they would indicate the opposite.
It doesn’t really matter at the end of the day, since we’re talking Post Stall maneuvrability but i can insure you that both Gripen and Rafale have pitch authority by the bucket.
http://www.mach-flyg.com/utg80/80jas_uc.html
Remember RIAT 2009 and the 11.0 g pulled by Ruet in a two seater Rafale B (200 kg heavier than the C), the instantaneous turn rate is extremly impressive, you don’t do that lacking pitch control.
Hence, with all these considerations, the foreplane position used on Eurofighter was chosen.
Yes, it is true in the frame of the aircraft design aerodynamic arrangement, with the inlet position they chosed and the sort of performances they were looking for within these parameters.
I do not think this applies to the close coupled canard arrangement with side or V-shaped inlets though.
I would assume from this that the slow speed pitch control environment would be the Rafales strong point for carrier approaches.
Not only carrier operations, low speeds, high AoA; during flight test the minimum speed demonstrated in control flight during mock combat vs Mirage 2000 was 15 kt, Maximum AoA 100* and 40 kt Negative speed, they never could depart the aircraft.
They have a similar corner speed but the Rafale is stressed for 11.0g if you compute turn rates on this structural load it can achieve higher turn rates (in theory).
Typhoon seems to be optimised for higher Mach than Rafale and Gripen i guess it would have the edge from M 1.6 to Mach 2.0, passed the wingload/lift coefiscient issue, Typhoon higher TWR tends demonstrate this point.
Agreed both designs seem very suitable to their intended functions.
They are indeed.
cheers
Pleasure.
About instability i did like this begginer’s vid very much…
Watch out for the aircraft departing from exces of AoA…
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