The International Rafale forum

Source: DATE:11/07/00
SOURCE:Flight International
Extreme manoeuvres

For the rest it is a question of how these aircrafts are used, in the worst case Rafale is given for an "average" of 7000 h including combat missions, take-off and landings.

This ongoing trolling about Rafale display in the AFM forum it typical of thise site, the guys write about what they visibly don't know or chose to ignore/distort, in particular about airframe integrity and structural g loads.

Frederic Ruet spoke about 9.0 g but the commentator said he spent 2.5 to 3 mn at g loads between 10 to 10.5 which BTW is far from being impossible.

...il va en passer 2.5 à 3 minutes avec des facteurs de charge de l'ordre de 10 voire 10,5g sur certaines mises en virage ou départ à cabrer.

The guys commenting doesn't invent anything; they are given a precise topo by the pilot or manufacturers for information purposes and if the Rafale pilot chose to pull 9.0 gs instead of 10.5 it is certainly more to spare himself physicaly then the aircraft.

I still have to get my hands on better videos but in certain cases i thaught i could read an AoA of 69/70° at speed below 250 kt, this wouldn't surprise me because the F/A-18 pilots can pull easly 59° AoA and still are revving about Rafale nose pointing capabilties.

This is not necessarily the worst. Airshow airframe may suffer more.

This means that during 2.5 to 3 minutes, the pilot will pull up to 10/10.5g for some turns. Not sustained.

In 2007, Mont de Marsan, the commentator announced the first Alpha Demo of Rafale, while Eric Gerard did the show.
In 2009, he talked about 294 Rafale instead of 286/288... He also talked about a max operational speed of M1.7.

Source: DATE:11/07/00
SOURCE:Flight International
Extreme manoeuvres

Extraordinary at high AOA

At M0.84, we climbed at an average rate of 12,500ft/min, and quickly reached an altitude of 25,000ft over Death Valley. Once level, I pulled the throttles to idle to set up for slow flight. At 260kt indicated, I selected "speedbrake" to aid deceleration. Unlike most aircraft, the Super Hornet does not have a dedicated speedbrake. The speedbrake function is performed by deflection of various control surfaces, including spoilers and ailerons.

Although the system does not actively seek a constant deceleration rate, selected control surfaces are deflected more as airspeed decreases and hinge moment loads decrease. I found speedbrake operation to be totally transparent, at no time causing more than a slight variation in pitch attitude.

Speedbrake deselected, we slowed down in level flight. Light airframe buffet was present at 17° AoA (130kt), but was gone as AoA increased past 25°. At 30° AoA, I selected military power and captured 35° AoA. I was able to control AoA to within 1° as we descended wings level at 6,000ft/min and 105kt indicated. I put in partial right rudder, and the aircraft smoothly entered a 30° banked turn. After a 60 ° heading change, I released the rudder and reversed the turn direction using left lateral stick - I hesitate to say "aileron", because the E/F's flight control system (FCS) can use a number of different surfaces to perform the "aileron" function. I found control responsiveness in all three axes (pitch, roll and yaw) to be excellent, with no wing rock or yaw wandering tendencies.

With wings level, in an effort to demonstrate the E/F's resistance to departure from controlled flight, I simultaneously put in full right lateral stick and full left rudder. This abrupt cross-control input had no discernible effect, the aircraft remained rock steady at 35° AoA.

Next, I reduced the AoA to 30°, with the aircraft in a 25° nose-high pitch attitude. I rapidly pulled the stick to the full aft stop and held it there. The aircraft pitched to 45° nose up, an increase of 20° from the stabilised value, as the AoA peaked at 59°. This large pitch reserve, available at such a low airspeed, will be useful should the Super Hornet pilot find himself in a close-range visual fight.

The aircraft stabilised wings level at 48° AoA and 70kt indicated, in a full aft stick stall. Aircraft heading tended to oscillate ±3° from the steady heading at about 2Hz. Seeking to prevent a departure in the yaw axis, the FCS actively uses yaw rate feedback to keep the aircraft pointing forward. One benefit of this control scheme has been the elimination of the "falling leaf" departure mode present in the basic Hornet.

A full left rudder input rolled the aircraft into a 45° banked turn, with AoA stabilised at 45°. A stabilised yaw rate of 6.25°/s was attained, and I was able to control aircraft heading accurately. After levelling the wings, I moved the stick to the full forward stop to recover from the stall. The aircraft pitched over to 40° nose low at an impressive rate of 17°/s.

Next, we performed a full forward stick inverted stall. As was the case with the aft stick stall, the aircraft was extremely stable, attaining a steady state AoA of -32° at -1g.

The final high AoA manoeuvre we performed was a vertical recovery. A military power 4g pull to a vertical attitude started the event. Heading straight up at 100kt indicated, I selected maximum power. At this extreme condition, the digitally controlled engines, which have no pilot-observed limits, responded by smoothly lighting both afterburners. I started the recovery by pulling aft stick to bring the nose toward the horizon. The nose tracked smoothly downward, and I released the stick when the aircraft was in an inverted, 20° nose-low attitude. Without any pilot inputs, the aircraft slowly rolled upright and stabilised in a wings level 30° dive. It was as if the Super Hornet knew how to complete a recovery from an extremely low-speed vertical attitude.

Pirouette manoeuvre

Finally, we performed a pirouette manoeuvre. This is essentially the Hornet equivalent of a hammerhead turn - a slow-speed, nose-high to nose-low, yaw rate turn in the near-vertical plane. When first developed, the E/F was unable to perform this stock Hornet manoeuvre, but modifications to the yaw rate feedback schedule put this back into the repertoire.

In military power, I started the manoeuvre at 210kt and 13,000ft altitude by pulling the nose up. At 150kt in a 65° nose high attitude, using slight aft stick pressure to keep the AoA above 25°, I put in full left rudder and left lateral stick. To my amazement, the aircraft yawed smoothly 180° to the left, ending up in a nose-low attitude on a reciprocal heading. Recovery to level flight and 200kt completed the manoeuvre. The entire operation took less than 25s, yielding a turn rate of about 8°/s.

Area work complete, we turned to the west for our recovery to Lemoore. Flight control laws limit maximum roll rate to 225°/s in an air-to-air configuration, and 150°/s with wing-mounted fuel tanks or air-to-ground munitions. At 15,000ft, I performed full lateral stick rolls at 240kt and 360kt indicated. At both speeds, a 360° roll was complete in less than 2s.

During our cruise home, I was able to reflect on the Super Hornet's manoeuvrability. The second leading cause of Hornet losses in the US Navy has been departure from controlled flight. At all conditions, the flight control system had allowed me to manoeuvre the aircraft predictably without regard to airspeed or AoA. The Super Hornet's demonstrated departure resistance is exactly what "carefree" manoeuvrability is all about.

While air traffic control vectored us to Lemoore, I explored some of the air-to-air (AA) and air-to-ground (AG) modes of the current Raytheon APG-73 radar. As well as the normal "B scope" AA presentation (azimuth versus distance) on the right DDI, I placed the azimuth versus elevation AA display on the left DDI. Although you could glean the same information from a single B scope presentation, having both a "God's eye" view and relative elevation display at the same time made it much easier to interpret the air-to-air picture.

Radar capabilities

The Super Hornet's AG radar display was impressive. The synthetic aperture radar (SAR) ground-mapping mode had three different levels of expansion (EXP), each expanding a smaller area to a higher resolution. The moving map display on the MPCD greatly enhanced my ability to use the EXP modes. For gross target acquisition, I did not need to use the radar display. Rather, I could slew the cursor over the target area on the moving map, and get an SAR expanded picture by hitting one of the DDI's side buttons. Each radar sweep built a more detailed and refined picture. From over 37km away, the SAR clearly showed Lemoore's runways, taxiways and hangars. After several sweeps, we could even discern the point on the ramp where we had taxied from an hour earlier.

Boeing and Raytheon have already begun development of an active electronically scanned array (AESA) radar for the Super Hornet. This will provide increased range and resolution in near-simultaneous air-to-air and air-to-ground operation. Raytheon is also developing the E/F's ATFLIR (advanced tactical forward-looking infrared) pod, which will replace separate navigation and targeting sensors and provide increased range and resolution.

The F414s have proven extremely reliable, but to simulate an engine loss Tysler retarded the left throttle to idle. Single-engined combat aircraft are widely accepted, but some operators still prefer a twin-engined design for just this contingency. Half flaps were selected for the single-engined instrument landing system approach to Lemoore's Runway 32L. Final approach speed for the 16,340kg aircraft was only 132kt indicated.

It shows that while you are able to control the aircraft up to high AoAs this is under careful flight testing conditions with manoeuvers being conducted in the vertical and with no roll performance at very high AoAs.

WVR is much about energy manoeuvering and such high AoA manoeuvers are rarely applicable on practical terms during a dogfight.

It only shows something related to the F/A-18, aircraft post-stall characteristics are drastically different from one type to the other.

It's all about tactics...

A gun-only fight will requier different tractics than those used by Rafale pilots to fight HMDs-equiped adversaries.

I can remember Adolf Galland saying that he could get his 109 "squaring" a turn INSIDE of a Spitfire mk 1 turn radius due to the better stall characteristics of the "Emil" (Leading edge slats), this is what a very high instantaneous turn rate does for the pilot.

Gun-videos shots shows the pilots breaking their speeds down to levels where the energy isn't showing in the HUD, while control remains in at least two axis, pulling the nose up get them the kill they're looking for, even for a IR AAM shot using HMD.

In the same videos the speed indicator goes up the scale again as soon as AoA is reduced, they also can do what the pilot did at the Oaris Airshow, reduce power, tighten the turn, if they pull 9 g the result will be a very fast and tight turn, then use full A-B to regain energy.

If you can do it at lower speeds, and retain roll control at the same time, your turn radius is going to allow you to stay inside of that of your adversary, if you have the thrust you also can yo-yo verticaly, which what the F-15/F-16 pilots does to counter the F-22 using TVC.

I don't think Rafales will ever perform P-S-Ms in airshows for quiet obvious reasons of safety, but at the Farnborough A-S where Rafale performed last, i saw Yves Kerherve do two descending 180* spiral turns at high AoA, each of those was performed faster chrono in hand then the Su Cobra maneuver, and this was with M-01 or M-02.

He did this straight from take off after a vertical climb.

Combat reports from Mirage 2000 pilots shows that they would loose their energy the very same way a F/A-18 would by tightening the turn even in a IR AAM shot, only the 2000 doesn't have any thrust in reserve, a Rafale has is by the bucket.

The effect remains the same at lower speeds and with higher AoAs the aircraft will roll slower, ofcourse some aircraft are effected to a lesser extend than others.

But during this tighten turns the aircraft will hardley reach its max. AoA. BTW what has a spiral turn in common with the cobra?

To be able to extend the flight envelope of modern fighter aircraft to high angles of attack , it is necessary to be able to control and guide the movement of the aircraft under very severe conditions characterised by extensive air separations on the fuselage and wings.

Such movements are necessary to be able to make difficult manoeuvres to combat a threat or to go into firing position during an air combat. These flight conditions require special aerodynamic performance capabilities involving new types of control surfaces and suitable flight models. These models are evaluated under operational conditions and are currently used for air combat simulations.



Scientific Experts :
D. Regard - Département Aérodynamique Appliquée (DAAP)
B. Dang Vu, A. Lesain - Département Commande des Systèmes et Dynamique du vol (DCSD)
http://www.onera.fr/cahierdelabo/english/amil4.htm

The slower the speed the higher the AoA requiered.

When you have higher energy level you need less AoA for the same amount of g, in the Ruet demo video often the aircraft reduces AoA once in a turn, he pulls quiet hard and the aircraft responds by giving a pick g load higher then 9 g with corresponding AoA.

I didn't check on Mirage 2000 videos but the aircraft visibly pitches-up a lot more than Rafale, when you notices it once you spot the difference quiet easly every time.

On the Rafale display video (Paris A-S 2009) you can read 422 kt/9 g/ 18* pick AoA.

I wonder which AoA did this Rafale pilot reach when he flew it down to 15 kt during a simulated combat vs a Mirage 2000...

The pointability is the relationship between the Cobra performed by the Su and the Rafale spirale.

ONERA and Dassault first CG-simulated, then flew post-stall maneuvers, it was found that the 100* AoA+/ -40 kt Cobra for example was causing a risk for the good Missile/aircraft separation.
http://www.onera.fr/images-science/simu%20...%20ctoire.php

So all these guys so critical of his demonstration have little idea of the level of skills requiered to a fighter pilot to compete at an Airshow with a display that compares rather favourably with that of more type-experienced company test pilots.[/b]

Not necessarily a high one when he flew a close to tail slight manoeuver. Would be interesting to know the details about the manoeuver.

Well TVC equipped Flankers like the Su-30MKI do a flat spin as well, the Rafale's spiral is more a vertical manoeuvre with full rudder when the speed is low enough and the aircraft more turns in the vertical?

The cobra manoeuver is a pitch manoeuver not a yaw manoeuver, that's the reason why I don't think these manoeuvers are hardly compareable, albeit you might refer to the nose pointing only?

Link is unfortunately dead.

I have just seen the video on the link and I have to say that I liked this demo very much.