# Tag Archives: Robin DR-44

## Refuelling or not refuelling?

Last week, I took my brother and sister onboard of one of my flight lessons. Ahead of the flight I reminded my instructor that I would bring them along and asked what flight route should I prepare. His response: “prepare the weight and balance report, the destination will be a surprise”. And so I did.

For those not initiated, each aircraft has a defined maximum take off weight (MTOW). Before the flight, the pilot needs to ensure that the aircraft will be below that weight. On top of that, the centre of gravity must be within certain limits. That is the weight and balance (1).

For a small simple aircraft like the Robin DR-44 we flew, it is a rather easy calculation that can be done with a pencil. See in the image below two ways of calculating it: making the numbers or using the graphic at the bottom of the image.

Weight and balance report for Robin DR-44.

Let’s review the numbers. We flew the DR-44 with immatriculation F-GSRR, which empty weight is 616kg. I estimated that the instructor and I, fully dressed and with headsets would weight ~160kg. My brother and sister behind, another 160kg. Baggages: I almost emptied mine and weighted it, 2.5kg. My instructor’s one is rather heavy, I assumed that together they would be 10kg. Principal fuel deposit: 110L of Avgas, with a density of 0.72kg/L, 79.2kg. Another 50L for the reserve deposit, 36kg.

Summing up: 1,061kg.

You can read in the image that the maximum take off weight for the plane is 1,000kg…

What to do then? Clearly, the aircraft is a given, so weight shall be reduced from somewhere else. But, from where? Either we left someone on ground or reduced baggage weight (my instructor left his and brought along only a book with aerodrome charts). However, baggage weight contributed only 10kg to the initial calculation. I then calculated: what is the maximum fuel we can carry?

Forget the reserve deposit: 36kg less. Let’s go with the principal deposit. What is the maximum fuel volume that would enable us to be within the 1,000kg limit? It would be somewhere about 80L (vs. the capacity of 110L of the deposit).

When I arrived to the aerodrome, I came with the message to my instructor: “Thierry, we can only carry 80L, if the plane is filled up with fuel, is there a way to purge it?” “No.” I then explained the numbers I had made and we went through them together.

Next step: check the fuel indicator of the plane… ~3/4… or about 80L, with the reserve deposit empty. We would be just within the limit!

We then proceeded with the preparation of the route, the pre-flight check, etc., and had good time with the flight (see report of the experience by my sister, in Spanish).

From this experience I learned a take away for future flights: when finishing your flight, it is normal etiquette towards the next pilot to refuel the aircraft if you see that the deposit is almost empty, however, it can be counter productive to fill it up completely if the next pilot is going to fly with passengers and close to the MTOW. I would then suggest that it is better to just fill it up to the volume where you know that the next pilot can have all choices open. For our DR-44 that would be filling it up to 3/4 of the main deposit (leaving reserve empty) (2). If the next pilot wants to travel along to a far distance needing more fuel he can always fill up more litres. This target weight will be different for each aircraft.

(1) See here another post I wrote two years ago about weight and balance calculations in the same plane model.

(2) Bear in mind that I found the airplane with precisely ~80L: coincidence or the previous pilot had come to the same conclusion at some point?

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Filed under Aerospace & Defence

## Flying to Corsica (2/3)

This post is a continuation to a previous post in which I described the first leg of our flight from Toulouse-Lasbordes to Corsica. If you haven’t yet taken a look at that one, I would recommend you to do so, as you would miss basic information and dozens of beautiful pictures of the French Mediterranean coast.

In the previous post I included images up until Cuers. There we refueled the aircraft and I took the controls of the aircraft, with Jean Louis (Asier‘s flight instructor) always by our side. This time Asier took the pictures.

Flight 2 (Javier at the controls): Cuers – Saint Tropez – Corsica – Sanguinary islands – Ajaccio – Propriano

Some curiosities about flying over the sea:

• the distinction in the horizon between “land” and sky wasn’t very clear thus it was very important to pay attention to the instruments in order not to lose references and keep a horizontal straight trajectory;
• as we progressed we always tried to spot ships down in the sea so in case of accident we would try to reach as close as possible to them, Jean Louis would do a water landing and we could be easily rescued;
• we needed to increase altitude up to flight level FL55 (5,500 feet -~1,700m- vs. about 700ft that we held at some times of the first flight along the coast) so we could keep receiving the signals from VOR on ground at the coasts.

First sight of Corsica: Piana.

Flying around the Corsican coastline: Cargèse.

Notice Jean Louis (the instructor) with the life vest on.

Cemetery of Ajaccio, looking like a village.

Jean Louis & me, at Propriano airfield.

The aircraft, a DR-44, put to rest for the weekend at the airfield.

Since we are normally flying within continental France we are not required to produce a flight plan for the air traffic control. This time as we wanted to cross over the sea to Corsica it was required to do so. Thus, this was the first time we prepared one (another learning point!).

“Olivia”, French site where to file a flight plan.

One remark: it is incredible how much eases the communication with air traffic controllers having sent the flight plan beforehand, as they expect you and they know beforehand more or less the information you are going to provide.

And so we made it! We flew from Toulouse to Corsica 🙂

It took us about 4h30′ of flying time (both flights combined). You may check the Garmin records of the first and second flights by clicking on the links, and the route we followed in this second flight in the picture below:

Even though I have mentioned above that we had planned for the contingency of having to water-land in the sea, the fact that the trajectory in the Garmin records stops at half way through Corsica in the middle of the sea does not mean that we indeed carried out such maneuver. Explanation: since we flew so many kilometers as compared to running (the normal use I give to the device), the memory of the GPS reached its maximum as it recorded one “lap” for every kilometer…

(to be continued…)

Filed under Aerospace & Defence, Travelling

## Flying to Corsica (1/3)

About 3 months ago, my colleague Asier and I went together with his instructor, Jean Louis, to Corsica for a weekend fly out, an activity of our club the Airbus’ Aviation Society.

The experience was terrific in several ways. I learnt a lot about flying and navigation the days prior to the fly out and during the trip. The views along the way by southern coastal France were superb. We enjoyed good weather despite of what had been announced and even found time to do some tourism and trekking in the island. But let’s go back to the flight.

On the way to Corsica, we made one stop at Cuers to refuel the aircraft and change pilot. Asier would start from Toulouse and I would continue to Corsica. On the way back, Asier would fly over the sea all the way to Alès and I would fly over Millau on the way to Toulouse.

I’ll try to be brief with the explanations and generous with the pictures to give you a flavour of how the French Mediterranean coast looks like. Because of the number of pitures I want to share, I will distribute them in 3 different blog posts, starting with this one dedicated to the first flight.

Flight 1 (Asier at the controls): Toulouse Lasbordes – Carcassone – Narbonne – Sète – Montpellier – Saintes Maries de la Mer – Fos-sur-Mer – Marseille – Cassis – Le Castellet – Toulon – Cuers

I encourage you to take a look at a map of France coast at the same time you are watching the pictures and try to identify the places (you may see the route at the bottom of the post as recorded by my Garmin).

See the life vests (yellow bags) at hand in case of emergency ready at hand. Jean Louis would have his vest always on. In case of emergency he would take the control buying us time to get ours on.

Carcassone from the North.

Narbonne from the North.

Peninsula at Étand de Thau.

Seafood plantation at Étand de Thau.

Ville de Sète.

Frontignan.

The touristic village “La grande Motte” built in the ‘60s and ‘70s with its characteristic architecture with forms resembling pyramids.

The intricate Port-Camargue, one of the first “pleasure ports” in Europe, also from the ‘60s.

Closed ponds at the mouth of the Rhone.

Bull fighting arena at Saintes Maries de la Mer.

Sands at Lagunes de Beauduc (with its non-paved driveway).

Lighthouse at Lagunes de Beauduc.

Colourful salt flats at Salins du Giraud.

Ships departing from the industrial hub Fos-sur-Mer.

Marseille and “Les Îles”.

Les Goudes and “Les Îles” (past Marseille).

Natural reservation of the “Île de Riou“.

Ideal and quiet spot at Calanque de Sormiu.

Former F1 “Paul Ricard” racing circuit and aerodrome at Le Castellet.

Military port at Toulon (an aircraft carrier can be seen).

Asier after having flown 2h30′ hours posing side by side our Robin DR-44.

You may check the Garmin records of this first flight by clicking on the link and the route we followed in the picture below:

(to be continued…)

## Wooden aircraft, cloth wings and pressure

Most of you, the readers of this blog, probably know that an airplane flies due to the difference in pressure between the upper (extrados) and lower (intrados) sides of its wing. This difference in pressure is due to the difference velocity of the airflow around both sides of the wing as you may see in the picture below:

Airflow around an airfoil (image from the Wikipedia, by Kraainnest).

As the speed above the wing is much higher, the difference in the pressure is mainly due to the lower pressure in the extrados. This can be seen in the following picture:

Pressure coefficient around an airfoil (by the Aircraft Aerodynamics and Design Group, Stanford University).

However, how could we see that in a real flight?

In commercial planes, of which wing skin is made of aluminium alloys this is not easily seen.

Two weeks ago, after my flight lesson was finished, I sat at the back of the plane to come back to Toulouse while my colleague had his lesson. It was then that I saw the image I captured in the following picture:

The aircraft we fly in our training lessons is a small Robin DR 400; a wooden aircraft of which wing skins are made of cloth. Not any cloth, but a type of polyester (PET) commonly used to build sailcloth, produced by Dupont and named Dacron. The surface is then lacquered with a polyurethane paint.

Robin DR 400 140

The air within the wing is at a higher pressure than the air in the extrados, and you can see how it expands and pushes up the cloth skin of the wing as you can see in the picture above.

You may see below the same wing on ground. Though the picture is of a lower quality, you can see that in this case the wing doesn’t look “inflated”.