March 18, 2012

Stall exercise

Yesterday, I wrote about a documentary on the AF447 accident. Within the video, a flight instructor performs a real stall exercises and he mentions that this is taught in the first lectures of flight instruction.

As I mentioned in the post, I learnt about the documentary while having lunch with 2 colleagues. I was telling them “I’d like to perform those stall exercises to see what feeling does your body have and how you instinctively react to it and how you have to consciously correct that reaction”.  As the old adage goes “be careful what you wish for ’cause you might get it”.

After lunch, we headed to the aeroclub to have our class. Thierry, our instructor, opened by asking whether we had seen that documentary we had been talking about. Then, he mentioned “let’s do today stall exercises!” :-)

Shortly, from the Wikipedia:

[...] a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. [...]
Stalls in fixed-wing flight are often experienced as a sudden reduction in lift as the pilot increases angle of attack and exceeds the critical angle of attack [...].

The theory of the exercise was easy: fly up to 3,000 ft, reduce the power of the engine down to idle, try to keep the altitude by pulling the stick backwards (nosing up), keep pulling the stick backwards when the stall alarm sounds off, wait until the aircraft starts buffeting, cannot maintain altitude and falls off… then push a little the stick (nose down), recover speed (above stall speed), start nosing up again while increasing power up to max rpm, get to 3,000 ft again. Easy.

The practice… well, my colleague was doing his exercises first while I was sitting at the back. I went from being warm due to the sunny weather to feeling uneasy to experiencing this cold sweat…

You may see the video below with one of the stall exercises performed by my colleague. You’ll notice the stall alarm (in this case it is just an alarm, not a voice saying “stall”):

Apologies for 1) bad quality of the video performed by my not-so-smartphone and 2) for not having recorded a video of my own stall exercises… I was too stressed with them :-)

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Note: For the record, in the documentary it is mentioned that pupils get to practice stall in their first lessons. Yesterday’s was my 10th flight in order to obtain the PPL (private pilot licence), up to then I had completed just slightly above 6 flight hours.

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March 17, 2012

Reconstruction of AF447 accident

The accident of the flight Air France 447 was deadliest in the history of the airline and, since it happened almost 3 years ago, has appeared every now and then in the media. Today, while having lunch with two colleagues I learnt about a documentary about it that was shown in French TV channel France 5 last Wednesday.

The documentary, produced by Bernard Vaillot, is titled “Vol Rio-Paris, les raisons d’un crash“,  lasts about 50 minutes, and the programme in which it was emitted included an interview afterwards (complete programme duration 1h08′).

The documentary includes as main attraction a reconstruction of the last 4 minutes of the flight. This reconstruction is built from the cockpit voice recorder (CVR) and the flight data recorder (FDR), often referred as black box. A complete transcription, with comments, interpretation and an exhaustive description of the events can be found in the different interim reports, briefings and releases made by the French BEA (Bureau d’Enquêtes et d’Analyses), the body in charge of the accident investigation.

In the BEA reports [PDF, 10.3MB, New Findings, pgs. 77-78] some facts were established: such as the loss of correct speed indication due to the icing of the pitot probes, the disconnection of the autopilot and the subsequent reaction from the pilot, pulling the stick towards him nosing up the aircraft, increasing the angle of attack until the aircraft enters in stall.

Other interesting features of the documentary are the testimonies of different pilots, including a real stall exercise performed by a flight instructor (from minute 25). He first shows how to recover from a stall, then he simulates the wrong reaction from the AF447 pilot, pulling the stick towards him, pitching up, while the stall alarm was still sounding.

You may see the following trailer below before venturing to see the whole programme.

EDIT: The trailer video has been deleted from Youtube, however, now the full video is available:

Unfortunately, I haven’t yet seen a subtitled or doubled version of it.

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March 16, 2012

Competing

Pierre de Coubertin said “The most important thing is not to win but to take part!”. After two years serving as Area Governor in Toastmasters, last weekend speech contest at Toulouse Rosemasters was the first time in which I could take part in speech contests again. I didn’t leave this opportunity.

Some people do not see what is in the competition for them. They tend to see it as very much American. Or they may think there is someone who is a better speaker, thus, no purpose in battling in the competition. Others may be afraid not only of public speaking but even more if there is a competition around.

I may understand those points, nevertheless I still think Toastmasters’ members should give it a try. There is always something to learn from that experience. My speech in the contest was a try to explain that.

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March 14, 2012

Weight and balance

As part of the preparation of a flight, the pilot shall make sure that the total weight of the aircraft (including fuel and passengers) is at or below the limits, and that the center of gravity is within a certain area. This is what is called weight and balance.

Some months ago, in our private pilot licence course we had a class where we reviewed this. I remember that one pupil asked “is it possible that the aircraft gets knocked over backwards on ground?” (imagine the aircraft “sitting” on its tail).

This question led me to make the numbers to see whether this was possible with the aircraft we are using for our lessons, a Robin DR 400.

Centrogram for a DR400-120.

For this purpose we use a centrogram, which is nothing but a small “map” where the different possible weights that can be loaded into the aircraft and its momentum are already drawn so the center of gravity can be easily calculated and checked whether it falls or not in the allowed area. This centrogram is included in the flight manual of the aircraft.

I found that, carrying 2 pilots (~154kg) plus 2 passengers (~154kg), you could never load much weight into the rear compartment reserved for baggage. As that area is the one behind the main landing gear, you wouldn’t knock over the aircraft on ground.

If instead of 2 pilots and 2 passengers, you had only 1 pilot and you would load the same weight (~231kg) as baggage, the aircraft would be unbalanced but still wouldn’t fall backwards and sit on its tail. Even if the center of gravity of the baggage compartment is behind the landing gear, the weight of the empty aircraft with a center of gravity between the nose and main landing gear over compensates our trick.

Once I had calculated this, I went one step further: in which cases being under the maximum take-off weight (MTOW, 1,000 kg for a DR400-140) given by the designer could the aircraft be unbalanced? That is, what is required to get the centre of gravity out of the allowable range?

I found that to get the aircraft unbalanced basically you would need to load it in two different ways that at first seemed quite bizarre to me:

  1. You would need to carry only 1 pilot and 2 passengers (plus at least 25 kg of baggage and bearing in mind not to exceed the MTOW), but instead of two of them occupying the front positions and one sitting at the back, you would have a single adult piloting the aircraft and the other two at the back. I’ve never seen that.
  2. You would need to have 1 or 2 adults piloting the aircraft, no passenger at the back plus at least 100 kg of baggage at the back. Why would one person carry so much baggage for a short trip with a Robin DR 400? Here I would add that the designer of the aircraft placed a small plaque indicating that no more than 40kg should be loaded in the baggage compartment.

Well, the two cases can be referred respectively to the following situations:

  1. A couple formed by future groom and bride flying alone with a pilot. Maybe that flight was used by the man to propose the marriage. Well, now you know it, that’s not a good idea, it could make the aircraft unstable (takeaway: no proposals in small aircraft).
  2. Drug-trafficking. I can imagine such small aircraft being used to carry as many drugs as possible… well, apart from being illegal, if someone would carry too much (that is over 100kg), even when below the maximum allowed weight, would make it unstable.

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March 12, 2012

Le Bal des Ambitions

Le Bal des Ambitions, 2009.

I learnt about the book “Le Bal des  Ambitions” in 2009, when a former colleague mentioned it and asked me to buy it in one of my trips to Paris. By then, I did not know French so as to read it, but some months ago I found it again in the aerospace boutique in Blagnac and grabbed it.

The book is written by two journalists, Véronique Guillermard and Yann le Galès, that in my opinion give an image history of EADS and the main characters who shaped it a bit too much thriller-like. Nevertheless, I found it interesting as I could recall many of the names and chapters, even though most of the stories happened either when I was still a student or had recently joined the company.

Some of the topics covered in the book:

  • Who are the so-called Lagardère boys, the relationships among them and with J.L. Lagardère. (I got to know who from some of top managers came from Matra and who from Aérospatiale.
  • It describes the merger discussions between Aérospatiale–Matra, BAE and DASA.
  • You get a glimpse of the role played by the grandes écoles in French networks.
  • The case of insider trading affecting top management of EADS in 2006.
  • Some of the issues behind the delays of A380 in 2006.

I guess that for a French native the text hasn’t got much quality, but for me, being my second book in French language, it was just perfect.

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February 29, 2012

Le Petit Prince

Le Petit Prince.

Last summer I visited an exhibition on occasion of the celebration of “2011 Year of Antoine de Saint-Exupéry”. Elsewhere he is mainly known as the author of “The Little Prince” (Le Petit Prince), however I learnt in that exhibition that in Toulouse he is mainly known as an aviation pioneer, flying airmail routes (for the emblematic Aéropostale based in Toulouse) and then for the French Air Force.

I guess that some of you had read Le Petit Prince early in your lives, I didn’t. I received the book as a present from former colleagues when moving to France and only finished it some weeks ago, being the first book I’ve read in French. Not bad for a start, as according to the Wikipedia it is the most read book in French language and was voted as the best book of the 20th century in France.

It has some idealistic messages or fine criticisms, to name a few:

  • “One sees clearly only with the heart. What is essential is invisible to the eye.”
  • A businessman who goes on “owning” stars and counting them not having time for anything else, not knowing what to do with them and having a very serious thought of him.
  • The geographer, proud of his profession, but who lacks any practical knowledge as “that” is the responsibility of someone else, the explorer in this case.
  • The concept of domestication being two-ways. I loved when the prince goes “Il y a une fleur… je crois qu’elle m’a apprivoisé…” (“There is a flower … I think she domesticated me …”) I believe this could be applicable to many pet owners.

I felt especially caught when the book first said “Les grandes personnes aiment les chiffres” (adults love numbers) and later when it went:

“Si les deux milliards d’habitants qui peuplent la terre se tenaient debout et un peu serrés, comme pour un meeting, ils logeraient aisément sur une place publique de vingt milles de long sur vingt milles de large. On pourrait entasser l’humanité sur le moindre petit îlot du Pacifique.

Les grandes personnes, bien sûr, ne vous croiront pas. Elles s’imaginent tenir beaucoup de place. Elles se voient importantes comme des baobabs. Vous leur conseillerez donc de faire le calcul. Elles adorent les chiffres: ça leur plaira.”

(“If the two billion inhabitants who people its surface were all to stand upright and somewhat crowded together, as they do for some big public assembly, they could easily be put into one public square twenty miles long and twenty miles wide. All humanity could be piled up on a small Pacific islet.

The grown-ups, to be sure, will not believe you when you tell them that. They imagine that they fill a great deal of space. They fancy themselves as important as the baobabs. You should advise them, then, to make their own calculations. They adore figures, and that will please them.”)

When I read the first paragraph and before reading the second, I was already writing a remainder note to make the calculation…

In demonstrations, the range of people per square meter is between 2 and 3.5 (4 being “like a rock concert”). A square of 20 miles by 20 miles covers an area of 1,035 millions of square meters. Therefore, in such a square we could pack between 2 and 4 billion people, the population of the Earth at the time, yes.

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February 23, 2012

Monaco GP Walking Tour

This post is about something I missed in Monaco.

There are many cities where walking tours are offered. We have taken some of those and are quite enjoyable. Not only they guide you through the city, but you get to look at the right spots in the right places, you listen to some of the stories that make up the history of the city, etc. We generally regard those walking tours as good value for money.

I missed such a tour in Monaco (and if it exists, we didn’t see it announced in the guide).

Let me share with you how easy it would be to organise it.

I would pick the circuit of the Formula 1 GP of Monaco as a reference. By the way, I found no explicit reference to it in the guide or in the city, you need to make it up yourself from memories of having watched it or check it in the internet (where normally it is not displayed street by street).

"Monaco GP Walking Tour" following the Formula 1 GP circuit.

As I said, I would give the tourist a map of the circuit and off we would go:

  • Departure at the starting line of the GP at Boulevard Albert I: from there you could easily venture to the left to see the centre of La Condamine, Rue Princesse Caroline, maybe walking up to the Place d’Armes to see the market.
  • Back to the circuit you would just go ahead till the first curve and visit the church Sainte Dévote, which gives the name to the curve in the race.
  • Taking the avenue d’Ostende up, you could venture to the Carré d’Or gallery, which is actually recommended in the guides. There you can see all kinds of luxury items’ shops (most of those brands don’t even ring a bell to me).
  • Leaving Av. d’Ostende you would continue to the Av. Monte-Carlo where you could visit the Casino, take some pictures in the gardens, admire the cars at the front (that spot is one that apparently every Porsche, Ferrari, Jaguar, Maserati or the like has to pass by no matter where they go :-) ) and take a drink at the Cafe Paris (all activities that are recommended in the guides).
  • Leaving Av. Monte-Carlo you would take the Av. des Spélugues where you would admire its curves, steep slope down and F1-like road borders.
  • Down at the Boulevard Louis II and prior to entering the tunnel, you could have a walk by the beach and see The Champions Promenade.
  • You would then go through the tunnel to appear again at the harbour, where you could admire the yachts.
  • Turn left at the Route de la Piscine (which last weekend was used for ice-skating) and end by having a final drink at the bar of the last curve, La Rascasse.

With this simple walk, of no much more than the 3.3km of the official Formula 1 circuit, you would have visited most of the highlights except for the Rocher, where the cathedral, the aquarium and the Palace are located.

If the walking tour was guided, someone knowledgeable of the city could tell you about the prices of houses, VIP residences, sums played at the casino, owners of biggest yachts, firms selling at the Carré d’Or, famous stunts and overtakes at F1 races history, etc, etc.

As far as I know, there is no such guided tour, above you have my two cents.

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