Almabraxas/1/The story of it

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This was our first prototype. Basically, it was a proof-of-concept: what is the cheapest way to get a video from the stratosphere ?

Contents

Administrativia

Getting an authorization from the aviation authority

Finding someone to talk to

Unlike what you may read on some sites, anyone can talk to the aviation authority to launch a balloon.

We got in touch with the DSAC (Direction de la Sécurité de l'Aviation Civile - Civilian Aviation Security Authority). It took only three phone calls. I already knew that France is divided into two regions for the purpose of aviation - Northern and Southern. We are in the Northern part, so I called the Northern DSAC, they're listed in the Yellow Pages. A lady replied.

-"Office of the Director, what can I do for you ?"
Uh ?
I'm just the little guy trying to launch a cheap probe balloon, may be the director of Civil Aviation Security for Northern France was a bit overkill. I tried to explain.
-"Is this DSAC ?"
-"Yes, I'm the secretary of the Director, what can I do for you ?"
I explained in a few words what I intended to do. She very kindly answered.
-"This is general aviation, please call one of the following numbers". And she gave me a list of four or five numbers to call.

I called the first one, again someone nice answered.

-"You should call my colleague Mrs R., she has the expertise for balloons", and he gave me another number, already in the list I got from the Director's office.

I then call Mrs R., and again found a very listening and useful interlocutor. She requested that we send her a document by email describing what we had in mind. I already had prepared such a document, so I sent it. (a small digression on Drupal and Wikimedia).

Finding a place to launch

This took some time.

We entered a fruitful dialogue with the aeronautical authority through Mrs R. At first, we just told them the site we had selected, however it happened to be too close to a major commercial airport. There are several of them in the Paris area, where we're located. We then explained our constraints. An important one was that we needed the authorization at least one week before launch. This is because of the delay to rent the helium bottle (the shop opens only one day per week). This was a problem for some sites we had proposed, because they were only suitable if the wind was in Eastern configuration: depending on the wind dominant direction, the commercial airplanes don't use the same circuits for landing and take off. And wind forecasts aren't available one week in advance.

Mrs R. suggested to use a meteo launch station not very far from us, however it was in the west of Paris, and the dominant winds blow from west to east. So the balloon would have to cross the high population density Paris district, an option I already had rejected for security reasons.

We made a new suggestion, this time it was close to an helicopter landing zone. People from the DSAC however, suggested three other close places, and we found them suitable. So we choose one of them.

The result

We finally got our authorization letter, signed by the Chief of the Air Operators and Airports subdivision of northern DSAC. The letter emphasized that a NOTAM would be emitted, and that we had to launch during the agreed time, a one hour window centered around the launch time we had indicated.

Talking with the insurance company

You can read on some web sites that amateur ballooning is legally ill defined, making an insurance coverage difficult. I can tell you first hand that this is not true, may be people don't have the right insurance company.

I gave a phone call to mine. I already got a RAQVAM insurance policy (Risques Autres Que Véhicules A Moteurs - all risks, except motor vehicles). I told them what I wanted to do. It took them a few minutes to check, and to my great surprise, they answered that anything was covered, if it was a hobby and was done by myself as a person, as opposed to an organization that should have its own insurance contract. This was a very relaxed discussion, so I asked if I was covered if my hobby was to launch elephants in the air, with a tissue as a parachute. The advisor didn't buy the argument, and, with a strong sense of logic, made a comparison with a hobbyist radio-controlled plane, a case known to them.

I later asked them to confirm their position in written, and in minutes, I got a letter. They basically repeated the covered risks in the very broad terms they were described in the contract, and just added a line saying that an amateur probe balloon was covered, given it was a personal project.

I was now clearly and officially covered until 100 000 000 € in damage (with a franchise capped at 5000), and my defense covered for possible litigation without limit.

The flight

Reaching the launch point

The day arrived. My wife, my two sons (5 and 3) and I went to my old buddy Christian's place with the material. Christian had already rented the helium bottle. We all took place in his car, and drove to the selected village. We turned around for some time to find the most suitable place, and then found it: a small separation path between two harvested wheat fields, with the chaff cutting like razors. A heroic place for our poor ballon, but we had plastic sheets to protect the ground, and a backup balloon in case things would go nasty. The motorway was about 1 km in distance, under the wind, and high tension power lines crossed the motorway, not far from us. So long for the simplicity. Also, there were a few trees here and there, but they were quite away from our launch point, and much lower than the electrical lines, so we didn't worry too much about them.

The setup

We set up the whole thing. We had time inside the 1 hour window the aviation administration had granted us, so we proceeded calmly. We attached the parachute, the radar reflector and the payload. Everything was more or less well, until we stumbled upon the first problem: how do you close and attach a probe balloon ? The one we got only had a tubular extremity, unlike others with a tube for inflating, and a ring to attach the payload. The inflating part was reminiscent of a condom for a horse, at least 4 mm thick and 30 cm long. We had no collar, but we finally managed to knot the tube like a party ballon and attached it to a rigid plastic ring, with a string to secure it.

That was the only remarkable event... Until then.

Countdown, with the kids holding the loose strings. 5..4..3..2..1. Let it go !

And very slowly, very majestically, the balloon started to drag the payload on the ground.

Damned ! It's not climbing ! The payload was too heavy !!! For the gaz we had put in the balloon.

I reviewed the numbers in my head. We needed less that one cubic meter to have enough lift, and had put 50% more, according to the manometer. Something had happened. We later discovered that the helium we had was not pure, and the manometer itself was far from being precise.

The setup, part 2

What to do now ? We didn't have enough helium to launch another balloon. And twenty minutes from now, our launch window would be closing, a long or short time depending on how you view it. We quickly took the decision to put more gaz into the balloon, however that meant we had to remove the knot on the inflating tube we had painfully tied. Now, how do you untie the 4mm thick horse condom ? If you're unsure, try to loosen the knot of a party balloon, and you'll get an idea of what our problem was.

Against all odds, we were able to do it, and had the inflating tube opened again. We put one more cubic meter of helium into the balloon. I thought it would make it burst at a relatively low altitude, may be 15 000 m (50 000ft) instead of the initially calculated 20 000 m. But we had no altimeter, and this was a proof of concept, we were not trying to break a record. So this was perfectly ok. And a lower altitude would translate into a shorter fly time, a shorter distance, and a greater chance to recover the payload.

We closed the end of the balloon again. And I then realized the bad thing. To put it simply, shit, fuck and damned ! There was a tiny hole at the base of the balloon ! Certainly, we had teared it during our multiple operations,

I put a patch of duct tape on it. However, Christian raised doubts: "The tape won't stick in the stratosphere at a temperature of minus 60 degrees (celsius, we're french, you know)". However, we were optimistic. As Christian put it "I believe in the power of the glue"[1]

Go !

New countdown. 10..9..8..7..

Questions popped in my mind. Was the balloon under-inflated ? Would it resist with a hole ? Would it only go 20 meters, or would it burst at the time of the launch into a pathetic failure ?

2..1..0 ! Let it go !

And very slowly, very majestically, the balloon started to lift and go ! It seemed to me it was quite slow, but at the time it was above the first tree, it was clear it already had climbed to an altitude of several hundred meters. It flew well above the motorway and the power lines without any trouble. Always higher ! It crossed the trajectory of a commercial airplane, although with an altitude difference of may be one thousand meters. We kept track of it visually for ten to twenty minutes. It went always further and higher and finally disappeared into the clouds, right into the direction we had predicted.

The flight, or what we know about it

The GPS GSM transmitter was sending the position of the ballon every minute. At first, it seemed to move relatively slowly, with respect to the ground, then faster and faster. After a few minutes, it had left the village where we had launched, and we had a first blackout. We weren't surprised, because we didn't expect a perfect GSM coverage of places we had precisely selected for their low population density. About ten minutes later, at about 12H20, we got a signal. The balloon was passing south of Brie-Comte-Robert, the last city before the vast and underpopulated plains of Champagne. It was cruising !

Time to celebrate and go for a lunch. We all went to the closest McDonald's for a happy meal (R).

According to our simulations, the balloon was supposed to make a 150 km flight and land about 50-75kms before the city of Reims, in a quite empty area.

At 14H40, after a one hour and a half blackout, we got a new signal. We had just had our coffee, so the timing was perfect. I read the cell phone and sweared. Everybody turned at me, wondering what was happening. The balloon was south of Reims ! It had followed quite closely the predicted trajectory ! It had been further of what we had expected ! There was only one possible explanation in our mind for getting this signal after the long blackout: the balloon was going down, braked by its parachute, and was soon to be landing !

We all packed into the car and hit the road. Our destination: the place close to Reims where we got the signal, 150km from the McDonald's.

This unique signal was the very last one we ever got from the balloon. Had we not had gotten it, we certainly never would have taken the car towards Reims.

The Trois Puits

We arrived at the Trois Puits, near Reims, the last known position of the balloon. There was a small hill dominating the valley. In front of us, fields and grape plantations were extending until the horizon (Reims is the region where the Champaign is produced). We stayed here and thought for a while, while the kids were having their hands on some pie. What had happened ? Along the trajectory were other villages. If the balloon had came close to them, certainly we would have got more signals, and we hadn't. Had the balloon landed in the depth of the valley, were no radio signal could escape ? Or just in a field too far from any populated place to be covered by our mobile operator ?

Decidedly no. Although we were unable to explain the lack of further signal, the balloon had to be here somewhere, we decided after much calculations and considerations.

We took the car again and patrolled the district for about one hour. But we were unable to spot anything, except a couple of hot air balloons flying, having nothing to do with our own. At 18H, a cell phone inside the balloon was supposed to ring, in case it had landed in a place where GPS wasn't precise enough, such as in a forest. Christian stopped the car. During long minutes, we listened with as much attention we were capable, trying to extend the sensibility of our ears by the power of our minds. But we didn't hear anything, except the songs of birds and crickets.

We soon realize we weren't looking for a pin in a haystack, but for a pin in a region covered with fields of hay ! Damned. The balloon wasn't sending anything, and the cell phone was unreachable.

Back to Paris

That was it, we would never recover the balloon. But we were ok with this outcome. We had knew since the beginning it was the most likely one.

We stopped at a shop to buy a dozen bottles of Champaign. At least we hadn't came here for nothing.

All in all, this had been a very pleasant day.

On our way back, at around 18H40, my cell phone rang.

- "Hello ?"
- "Hello. I've found your balloon in my field !"

Of course, we had put a label on the payload box with my phone number and email, in case someone would find it.

- "Where are you Mrs ?"
- "I'm in Vielsalm".

We looked at the map. Vielsalm is in Belgium, a few dozen kilometers from the German border. The balloon had followed its trajectory, but it had went much further what the simulation had told us ! It had crossed France ! And Belgium ! A 450km trip ! And we didn't even had requested a clearance to fly over Belgium.

And better than that, we knew were the balloon was, and it was in good hands.

Lessons learned

  • The GPS-SMS transmitter is far from being a good solution. Almabraxas-2 will use a HF transmitter.
  • Don't hesitate to put a bit more helium than expected (or calculated).
  • Lens must be heated.
  • Launch on a sunny day,you may avoid some ice on the lens.
  • You may have several media sources (video, telemetry, GPS), be sure to have a way to synchronize them so you can tell what happened when, and in what condition.
  • Have a more precise regulator
  • A ring is much more than a simple tie !

See also the videos.

Notes

  1. "Je crois au pouvoir de la colle", which in French sounds very much like "Je crois au pouvoir de l'alcool" (I believe in the power of alcohol)" :-).


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