Here are two very useful videos about the semi-circular rule. The first one is in English, the second one in French:

Pour la seconde vidéo, on peut ajouter que si les niveaux de vol 55, 75 et 85 (pour les routes magnétiques vers l’est) sont valables en VFR (régime de vol à vue), on devra emrunter en vol IFR (vol aux instruments) les niveaux de vol 50, 70, 80 et 90 par exemple. C’est à dire qu’en IFR on n’utilise pas les niveaux de vol se terminant par 5 mais par 0 et cela est valable pour les routes magnétiques allant vers l’ouest (FL 80, FL 90, etc). La règle semi-circulaire est utile aussi pour le module NRS (Navigation, Réglementation et Sécurité des vols) au BIA-CAEA. D’autres informations très intéressantes sont disponibles sur ces chaines Youtube:



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 This special fuel could drip and leak abundantly as the airframe made up of titanium was retracted while taxiing, and became airtight only when it got its operating shape while flying very fast and very high because of the air density, and surrounding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


For language training purpose only


New-York to Los Angeles in 12 minutes… It would have been a record-breaker, had it worked:

The DARPA and USAF FALCON project might give anybody the thrill of speed as this « aerospacecraft » has been designed to reach Mach 20 i.e. around 20,000 km/h; 5.6 km/s; 10,800 knots; or 12,400 mph depending on the air temperature, and the altitude which might be above at least FL900!

DARPA USAF FALCON HTV-2 hypersonic aerospacecraft - 22 April 2011
DARPA HTV-2 - 22 April 2011 ---- Photo: DARPA, US Federal Government

Unfortunately, the project seems to encounter major difficulties as the last test which unfolded on August 11, 2011 failed again. The previous one – also on an HTV2 – had failed in April. Click on the right-hand side picture to get further information on the first test. The Blackswift (HTV-3X)  had been designed by ATK; Boeing; Lockheed Martin; and Skunk Works to provided a strategic strike anywhere in the world within an hour. It was cancelled due to a lack of funds (see the HTV-3 shown in the following video):



  • DARPA stands for Defense Advanced Research Projects Agency
  • FALCON stands for Force Application and Launch from CONtinental United States
  • FL stands for Flight Level (FL x 100ft = altitude)
  • HTV stands for Hypersonic Test Vehicle or Hypersonic Technology Vehicle
  • RCS means here in the videos: Reaction Control System (and not Radar Cross Section)

Click on the picture below, and then on the blue arrows to watch the different phases of light:

Flight Overview slide, MACH-20 DARPA AEROSPACECRAFT
Flight Overview slide - Interactive picture: DARPA, U.S. Federal Government

FLYING from Paris to New-York in 1.5 hours at Mach 4 !

This is the brand new project being designed by EADS, and supported by Japan as well as the French DGAC (Direction Générale de l’Aviation Civile – FAA or CAA equivalent). The European consortium has just unveiled its ZEHST project as the Paris Air Show 2011 is opening. ZEHST stands for Zero Emission Hypersonic Transportation.

This aircraft would be both a commercial airplane, and a rocket. It could cruise at « flight level 1056 » i.e. 20 miles or 32 kilometers above the mean sea level… The ZEHST specifications feature a speed of Mach 4 but according to the video below, it might reach Mach 4.5 i.e. 5,500 km/h or 3,000 kts through the stratosphere. It would use two independent turbojets for taking off, then it would gain speed thanks to two cryogenic rocket engines, finally two ramjets would propell the aircraft to hypersonic speeds.

The ZEHST is supposed to pollute far less than the Concorde as it would have a main cruise stage in the stratospheric layers, and according to EADS, its carbon footprint should be very low. There could between 60 and 100 passengers on board who could join Tokyo from Paris in 2.5 hours instead of 11.5, and New-York in 1.5 hours instead of 8! The prototype is expected to fly by 2020, and the first passengers might enjoy stratospheric flights around 2050.

Watch the video: