WING LIFT THEORY SHAKEN – LA THÉORIE DE LA PORTANCE DE L’AILE ÉBRANLÉE

I had already written about that in my book UNE AUTRE HISTOIRE DE L’AVIATION, on pages 12; 13; 71; and others – Bernoulli’s principle does not explain everything. We know that aircraft fly. Strange as it may seem, Bernoulli’s principle has often been taught for decades as the explanation of the phenomenon.

Je l’avais déjà évoqué dans mon livre « Une autre histoire de l’aviation » aux pages 12, 13, 71, et d’autres: Le théorème de Bernoulli n’explique pas tout. Nous savons que les avions volent. Depuis des décennies, aussi bizarre que cela puisse paraître, on enseigne souvent le théorème de Bernoulli comme l’explication principale au phénomène.

This explanation would make sense if the air particles split at the leading edge of the wing and come together at the trailing edge. However, Cambridge researchers had debunked this flying myth in 2012, and have recently confirmed that Bernoulli’s principle cannot explain everything in wing lift. As you can see on the video above, the upper wing air stream travels much faster than the lower wing one. Last but not least, these air streams do not come together at the trailing edge since the upper wing air stream reaches the trailing edge well before the lower wing airflow. Isn’t this amazing?

Cette explication tiendrait si les particules d’air se séparaient au bord d’attaque de l’aile et se rejoignaient au bord de fuite. Cependant, des chercheurs de Cambridge avaient démonté ce mythe du vol en 2012 et viennent de confirmer que le principe de de Bernoulli ne peut pas tout expliquer dans la portance de l’aile. Comme vous pouvez le voir sur la vidéo ci-dessus, le flux d’air en extrados voyage beaucoup plus vite que celui d’intrados. Enfin et surtout, ces flux d’air ne se rejoignent pas au bord de fuite puisque le flux d’air d’extrados atteint le bord de fuite bien avant le flux d’intrados. Étonnant, n’est-ce pas?

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PILOT ESCAPING THROUGH UNDERWATER EJECTION

Do you remember that some fighter pilots could safely eject from underwater back in 1965? Could it be survived? One may wonder but a few ejections were reported. The transcript is below the video. Look at that canopy, it looks like it came from an F-8 Crusader:

TRANSCRIPT:

If your aircraft has provision for underwater ejection, you have a ready-made, secondary escape route. Succesful underwater ejections can be made from any aircraft attitude – nose down, tail down, and inverted.

Escape by this method requires no preparation other than that recommended for normal seat ejection. There should be at least ten feet of water above you before you can safely eject. Never eject from the surface. With present systems, the chute cannot open with a zero-zero situation (which means at a height of 0 and at a speed of 0). The effect of free-falling 80 feet to water is little different than falling 80 feet to concrete. True, some lucky ones have lived to tell about it. But it is one hell of a gamble.

When you eject through the canopy underwater, the seat breaks through clearing the way for your body. Because water resistance imposes terrific forces on your head and neck, it is vital to hold the face curtain tight against your head for support. The forces of ejection might cause a momentary blackout. Immediately upon collecting your wits, disconnect yourself from the seat by pulling the emergency release handle breaking your restraints. Now, separate yourself from the seat. This is difficult. You will have to kick and swim violently even though you are disconnected.

If your chute gets hung up on the seat, do not waste time trying to clear it. Release your riser fittings and swim clear off the chute. Do not inflate flotation equipment until clear of the seat. Remember, surface slowly, exhaling as you go. Remove your oxygen mask.

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CHINESE J-31 STEALTH FIGHTER AIRCRAFT

The brand new 5th-generation fighterjet Shenyang J-31 – or F60, which would be nicknamed Gyrfalcon – took off on October 31, 2012. She thus performed a test flight – probably her maiden flight – on Wednesday.

This futuristic PLAAF (People’s Liberation Army Air Force) stealth multirole jetfighter looks like an F-35 Lightning II though the Gyrfalcon (or Falcon Eagle?) turns out to be a twin-engine a/c. She would be more maneuverable but smaller than the latest Chengdu J-20 Black Eagle stealth fighter. Her radar cross section (RCS) might be very small, and stealthier than recent 5th-generation fighter aircraft as the radome mounting looks as if it were – like the rest of the airframe – designed with reentrant shapes.

This fighter aircraft would not exceed Mach 2, and she features a DSI (Diverterless Supersonic Inlet) so that the airspeed can be reduced while entering the air intake, thus preventing the engine from breaking up.

Here are a few pictures, and videos:

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Mach-3 SR-71 Blackbird’s HOT COCKPIT

Blackbird onboard USS Intrepid – Photo © Xavier Cotton http://www.passionpourlaviation.fr

As you may have heard, the mythical Lockheed SR-71 Blackbird was a strategic reconnaissance aircraft able to fly at more than Mach 3 – Mach 3.3 ie around 3,500 km/h; or 1,900 kts; and at a maximum flight level of… FL 850 or 26 kilometers high!

The Blackbird indeed had a unique flight envelope with a particular doghouse plot (since she could not exceed 3.5 G), and an exceptionnal coffin corner limited by her CIT – Compressor Inlet Temperature of 427°C maximum.

This aircraft was also unique for her engines were two J58 ramjets fuelled by JP-7 especially refined for extreme flying purpose. This special fuel could drip and leak abundantly as the airframe made up of titanium was retracted while taxiing, and became airtight only when it got its operating shape while flying very fast and very high because of the air density, and surrounding pressure plus the heating caused by the air friction at such speeds. In short, the whole structure considerably expanded when airborne.

The irony – I heard it on the grapevine, or read it somewhere on the web – that titanium which turned into dark blue while flying (SR-71s probably deserved those unofficial other nicknames « Bluebird », or « Habu » viper) was « imported » from… USSR!

Pilots must have taken significant risks inherent in flying such an aircraft as mentioned in this previous post. These pilots used to fly over the USSR to take strategic reconnaissance photographs during the Cold war. They wore pressurized spacesuits so that their blood could not boil in case of decompression or ejection at such altitudes.

The Blackbird travelled faster than a rifle bullet, and the air friction could have melt aluminum-skinned aircraft. At Mach 3.2, fuel cycled behind the chine surface in order to cool the aircraft! The inner windshield temperature could reach 120°C even though a heavy-duty cooling system was on a full function. On landing, the outside temperature of the canopy could reach 300°C, and it must have been far beyond on the fuselage, and wing surfaces while flying at high speeds. The pilot could feel the heat behind his protective gloves!

Special thanks to Xavier Cotton for the Blackbird photos. Please, visit his website on http://www.passionpourlaviation.fr

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Future Airbus Aircraft Concept

This is what the next Airbus aircraft should be in the 40 years to come. The new Airbus concept is to match the passengers’ demand.

According to a consultation with the customers, 96% of them want more environmentally sustainable aeroplanes. The aircraft of the future will have to be fully recyclable, more sustainable ie eco-efficient, and less stressful:

Now, the leading aircraft manufacturer is using the feedback to paint its vision of sustainable aviation in 2050.

Airbus had unveiled a revolutionary concept cabin through images of a transparent airliner design, last year.

There is a need among the passengers to reduce the time spent in airports. The new Airbus concept cabin will integrate an additional door for faster boarding, and exit. This airliner of the future will reduce its noise, and carbon emmissions. It will use the latest technologies – bionic structure, blended airframe, enhanced laminar flow and noise reduction; blended U-tail, biomorphing seats able to collect the passenger’s body energy, cutting-edge relaxation systems, human body thermal recycling, dramatic panoramic view, World Wide Web access, round of golf, etc. Watch the video:

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