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 have recently debunked this flying myth. 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 ont démonté ce mythe du vol. 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?

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

Airbus unfortunate glitches at Paris Air Show 2011

The Airbus flagship A380 had a winglet clipped off by a building while taxiing or parking:

Moreover, the brand new Airbus A400M military cargo aircraft got an engine failure. The A380 would have flown back to Toulouse so that it can be fixed, and take part to the Paris Air Show again. As far as the A400M is concerned, it is likely to remain grounded unless the engineering team find a solution to repair the gearbox.

Special thanks to Xavier Cotton (http://passiondesavions.blogspot.com/) who passed the video link on.

AIRBUS VISIONARY PROJECT – TRANSPARENT AIRLINER

Airbus has just unveiled a revolutionary concept through images of a transparent airliner design.

This aircraft of the future will use the latest technology – bionic structure; blended airframe; enhanced laminar flow and noise reduction; blended V-tail; biomorphing seats; leading-edge relaxation systems; human body thermal recycling; dramatic panoramic view; round of golf; etc.

Airbus will showcase their project called Concept Cabin during the Paris Air Show, at Le Bourget Airport. A movie – Airbus Future of Flight – will also be shown in a 360° planetarium at the Musee de l’Air et de l’Espace from 20 to 26 June 2011. Watch what travelling by plane could be… 40 years ahead:

Special thanks to Thierry HERMAS – Aeronautical English teacher at the French Air Force Academy (EOAA, Salon de Provence) – who passed the video link on. Thank you very much indeed.