Tailstrike sur A380. Test ou ???

[Warlordimi]

ou pilote qui fait mumuse?

Si test, quelle utilité?

http://fr.youtube.com/watch?v=q5QlQpfOt ... re=related

[Azrayen]

Test.

Utilité : connaitre la vitesse minimum nécessaire pour se mettre en l'air.

En l'occurrence, si tu regardes bien, l'avion est spécialement équipé pour le test (sabot). En revanche, il semble bien que le fuselage touche aussi (légèrement, ouf) en début de montée.

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Az'

[Flyingtom]

Test de la Vmu : Minimum Unstick Speed

[Warlordimi]

Oui, j'avais tiqué sur la couleur rouge du "sabot" et la faàon dont le pilote insiste, mais vu que le fuselage à pris également, je doutais.

Je me souviens d'un 747 de la SABENA qui était resté coincé qques jours à Kinshasa après avoir raclé le seuil de piste de la sorte!

[Azrayen]

Ah, merci Tom !

Pas moyen de retrouver l'acronyme correct...
Vexant quand tu viens de finir le bouquin de J. Rosay...

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Az'

[SpruceGoose]

... dont l'utilité se résume comme suit :

The next velocity of interest to us is that at which the aircraft can begin to rotate its nose into the air, conveniently called the rotation speed, Vr. While Vr must be at least 5% greater than Vmc, it need not be any greater than V1.

Next comes the minimum unstick speed, Vmu, which defines the point at which the aircraft could take off if the maximum possible rotation angle were reached. This maximum angle would occur if the tail of the plane were to actually scrape the ground.

Since such a takeoff would be damaging to the plane and most unnerving to passengers, the aircraft actually lifts off at a slightly greater velocity called the liftoff speed, Vlof. Liftoff speed must be at least 10% greater than Vmu when all engines are operating and 5% greater when one engine has failed.

Now that our happy little plane has finally become airborne, it accelerates into takeoff climb speed, V2, which must be reached at an altitude high enough to clear a given obstacle. For FAR 25 aircraft, the obstacle clearance height is 35 ft (10.7 m). The takeoff climb speed must be at least 20% greater than stall speed, Vs, and 10% greater than Vmc.

[*Aquila*]

ou pilote qui fait mumuse?

On ne fait pas trop mumuse avec ce genre de joujou... Surtout ce genre de mumuse!

[SpruceGoose]

Apparemment certains tailstrikes en opérationont eu de graves conséquences.

Tailstrike incidents rarely cause significant damage or cause danger, but may cause financial losses as the planes have to be thoroughly inspected and repaired.
However, improper repair to the damaged airframe after tailstrikes accidents are responsible for fatal accidents that occur years later due to structural failure of the airframe at the site of the tailstrike after repeated cycles of pressurization and depressurization at the weak point of improper repair.

Japan Airlines Flight 123 (B747)
The official cause of the crash according to the report published by the Japanese Aircraft and Railway Accidents Investigation Commission is as follows:
1. The aircraft was involved in a tailstrike incident at Osaka International Airport on June 2, 1978, which damaged the aircraft's rear pressure bulkhead.
2. The subsequent repair performed by Boeing was flawed. Boeing's procedures called for a doubler plate with two rows of rivets to cover up the damaged bulkhead, but the engineers fixing the aircraft used two doubler plates with only one row of rivets. This reduced the part's resistance to metal fatigue by 70%. According to the FAA, the one "doubler plate" which was specified for the job, (the FAA calls it a "splice plate" - essentially a patch), was cut into two pieces parallel to the stress crack it was intended to reinforce, "to make it fit".[5] This negated the effectiveness of one of the two rows of rivets. During the investigation Boeing calculated that this incorrect installation would fail after approximately 10,000 pressurizations; the aircraft accomplished 12,319 take-offs between the installation of the new plate and the final accident.
3. When the bulkhead gave way, it ruptured the lines of all four hydraulic systems. With the aircraft's control surfaces disabled, the aircraft was uncontrollable.

China Airlines Flight 611 (B747)

The final investigation report found that the accident was the result of metal fatigue due to inadequate maintenance after a previous incident. The report finds that on February 7, 1980, the accident aircraft suffered a tailstrike occurrence in Hong Kong. The aircraft was then ferried back to Taiwan on the same day de-pressurized and a temporary repair was conducted the day after. A permanent repair was conducted on May 23 through 26, 1980. The permanent repair of the tail strike was not accomplished in accordance with the Boeing SRM, in that the area of damaged skin in Section 46 was not removed (trimmed) and the repair doubler did not extend sufficiently beyond the entire damaged area to restore the structural strength. Consequently, after repeated cycles of depressurization and pressurization during flights, the weakened hull started to crack gradually and finally broke open in flight on that flight, exactly 22 years after the faulty repair had been applied to the damaged tail. An explosive decompression of the aircraft occurred once the crack was broken, causing the complete disintegration of the aircraft mid-air.

***

[Scrat]

ou pilote qui fait mumuse?

Si test, quelle utilité?

http://fr.youtube.com/watch?v=q5QlQpfOt ... re=related

C'est marqué en commentaire de la vidéo...

[pilfranc]

C'est vrai qu'il racle bien quand même.....

[Warlordimi]

On ne fait pas trop mumuse avec ce genre de joujou... Surtout ce genre de mumuse!

Je me souviens avoir vu des pilotes d'essai faire un tonneau en 707 et en Concorde, alors bon...

[Flyingtom]

Test du A340

[fockewulf]

En concorde ? C'est sur, ca ?

[*Aquila*]

Je me souviens avoir vu des pilotes d'essai faire un tonneau en 707 et en Concorde, alors bon...

En concorde, pas sûr. Quant au 707, autres temps, autres moeurs. Et le pil' s'est fait remonter les bretelles jusqu'au chapeau. Non, ce temps n'est plus! Et puis dis! Un gros tail strike pour rigoler, ça fait fort de café non? :laugh:

[Booly]

En concorde, ya bel et bien eu un tonneau, lors des essais de la machine... j'avais vu passer un docu télé avec l'interview d'un des anciens pilotes d'essai, qui disait que le concorde se comportait tellement comme un avion de chasse qu'il a voulu tester le tonneau, et que c'est passé comme une lettre à la poste ^^

[*Aquila*]

Ce qui me donne un doute, c'est que ça ressemble furieusement à l'interview du pilote d'essai du 707!
http://fr.youtube.com/watch?v=FJyAyopu2_c

[Warlordimi]

En concorde, ya bel et bien eu un tonneau, lors des essais de la machine... j'avais vu passer un docu télé avec l'interview d'un des anciens pilotes d'essai, qui disait que le concorde se comportait tellement comme un avion de chasse qu'il a voulu tester le tonneau, et que c'est passé comme une lettre à la poste ^^

Même source surement!

[SpruceGoose]

Tonneau executé par le celèbre pilote d’essais de Bell Aircraft puis Boeing Tex Johnston.
Appareil B367-80 (prototype du B707) appelé Dash80.

Extrait de son livre : Tex Johnston, Jet Age Test-Pilot / T Johnston - C Barton / Smithsonian

"Good, Carl Cleveland in public relations will arrange the time." That ended my hydroplane aspirations. Cleveland called Friday evening and said the Dash 80 fly-by was to follow the Blue Angel show and gave me a time hack.
The weather on Gold Cup day was impeccable. My flight crew included Jim Gannett, copilot, and Bell Whitehead, test engineer. We completed our test over the Olympic Peninsula, and as I turned to a go-degree heading for Lake Washington, I told Jim, "l'm going to roll this bird over the Gold Cup course."
Jim's head snapped around, his eyes wide, his mouth slightly open in surprise. "They're liable to fire you."
"Maybe," I said, "but I don't think so. There are more than two hundred thousand spectators. Everyone in the airplane and airline business in the world is hère. This is the airplane that's going to dominate the industry for forty years. We're going to get their attention and make this airplane famous." I pulled the nose up and executed a leisurely climbing left barrel roll, and then began the descent to Lake Washington.
I observed the Blue Angels' last pass and their departure for Sand Point Airport four miles north of the racecourse. Approaching from southwest of the lake on a northeast heading, speed 490 mph, altitude 200 feet, we passed over the racecourse, pulled up in a left chandelle, pulling 3.5 G in the vertically banked left turn to 1,500 feet altitude.
Proceeding on a southwest heading in a shallow dive across the racecourse to 300 feet altitude, speed 490 mph, I established a 35-degree climb and released the back pressure. The airplane was climbing at 1 G, the same as level flight. I applied full left roll control and, as the airplane approached the inverted position, applied slight back pressure, bringing the nose down slightly to maintain 1 G, continually holding full left roll control. The roll was completed in level flight at 1,500 feet altitude.
Executing a 18o-degree nose-down turn, we again passed over the racecourse at 490 mph and executed the second climbing roll. During the two barrel rolls the airplane never knew it was inverted. The entire roll maneuver was executed at 1 G, the same gravity force as at level flight. Whitehead, the test engi-neer, knelt by a passenger cabin window and snapped the today-famous photo of the Dash 80 inverted over the Gold Cup course.

***

[Black Wolf]

Une vidéo de ce tonneau en meilleure qualité que celle de l'interview http://youtube.com/watch?v=3IV9PZW1N9U

[Knell]

Soyons puriste, ceci n est pas un tonneau mais un tonneau barriqué ..
j'insiste !

[Booly]

Voilà, j'avais vu ce reportage-ci, traduit en VF sur la chaine publique Belge à l'époque (c'est du BBC, si je ne m'abuse), et j'imagine que Warlordimi a vu le même... malheureusement, ici, c'est en anglais, désolé pour les non-pratiquants de la langue du chat qui expire
Le pilote en parle (mais pas de vidéo du barrel roll)...
Brian Walpole speaks about the barrel roll in a Concorde

[TooCool_12f]

le concorde a effectué deux tonneaux barriqués au moins. un à droite et un à gauche, aux commandes le pil d'essai français et le pil anglais pour l'autre.. y a aussi une vidéo d'interview du pil anglais qui en parle:

http://youtube.com/watch?v=KYQS3qAIjAo&feature=related

[TooCool_12f]

arf grillé