No flame hot air balloon

In 1993, a french enginneer, Jean-Paul Domen has discovered how to fly an hot air balloon without using flames. The prinicipe was to use hot saturated air inside a black enveloppe. This created a light thunderstorm inside the balloon and so, the inside temperature was higher than outside an the balloon flies. The first tests were made in 1993 and were successfull. The test balloon was named 'Bulle d'orage'; It climbed up to 33000 feet maintaining a rate of 400 feet/minute.

Since then, no news ! seems this fantastic project was aborded.

Anyone knows ?

What is 'hot saturated air'?

William W. Plummer a écrit dans le message

good question ! this is the genious of this french men. I try to explain you but this requires a few lines. Please keep in mind english is not my 'best' language so excuse me if a few mistakes are present. Also all is in metric but I guess you will easy convert if needed.

Hot air is lighter than cold. I hope everybody on this forum knows this. At sea level, air has a volumetric mass of 1,293 kk/m3 at 0°C, 1,225 kg/m3 at 15°C and 1,150 kg/m3 at 33°C. So, a 2.200 (70,000 cu.inches) balloon with a 16 m diameter, filled with 33°C air, will lift 75 grams/m3 or 150 kg overall, including balloon weight. So far, nothing new.

Let's have a look at an hot air bulbe as it climbs inside a balloon enveloppe: Since this air climbs, it becomes cooler everybody knows this. A climbing dry air mass into atmosphere, will cool at a rate of about 10°C per 1000 m. According to meteorologists, atmosphere itself cools 6,5 °C per 1000 m.

So, if a mass of hot air climbs in cooler atmosphere, it will be cooler faster than atmosphere itself. This air mass will thus stop climbing very soon. Atmosphere is naturally stable and this is good otherwise we will live in a permanent storm. Storms, ouragans, thunders, are an unstable manisfestation of atmosphere due to the presence of humidity (vapor) inside air. Opposite to dry air, a humid air mass may have a cool gradient lower than those 6,5 °C/1000 m of atmosphere. So, a humid air mass at 37°C will only loose 4°C as it climbs 1000 m.

You may ask why. Just because as soon as temperature diminue, a part of the vapor can not stay mixed with air. This vapor will condense and become a kind of fog. Physical experiments has prooved that 1 gram of water condensing will give back the 2500 joules wich were necessary to evaporate it and this phenomena will slow the coolling process. There is the same energy quantity in 20 grams of air condensing than in 1 liter of burning petroleum. Thsi phenomena gives the necessary energy to thunderstorms to stay active a few days. A thunderstorm may contain 10.000.000 tons of water vapor equivalent to 500.000 tons of petroleum !

To be convised, make this experience : boil water. There is a moment where water will be transformed in vapor and then, you can warm as much as you want, water temperature will remain at 100°C. All the warming energy will be used by the water transformation.

Now, let's look what happend inside the balloon.

Let's assume this is a standard day with 15°C temperature at sea level. We fill a 2.200 m3 balloon (preferably in polyurethane and of black color) with air at 37°C. The inside temperature is thus 22°C warmer thant outside air (37 - 15 = 22). The air we will use to fill the balloon will be water saturated (40 grams / m3). At take off, no miracle, the ballon will climb. What will happend as the balloon will be at 1000 m ? A part of the water will condense and form a fog as soon as outside temperature will start to cool and any single gram of condensed water will slow down the cooling process inside the balloon. The inside air will cool at a rate of 4°c and thus, at 1000 m, the inside air temperature will be 33°C ( 37 at start - 4 = 33). We can immediately understand that the balloon will continue his climb and more of that, will accelerate his climb. Look at this : At sea level : outside 15°C inside 37 difference = 22°C At 1000 m: outside 5°C inside 33 difference = 28 °C

and this will continue until all vapor will have condensed in other words, when the outside air temp will not decrease anymore in theory 12186 meters.

Note that I have not taken in account the heat lost by surface contact since this is compensated by the solar radiation on the black balloon.

Better view now ? Do not try to fight against this. It really works ! all tests have been positive. Better than hydrogen or helium, no need of any external power, no pollution, no noise, can not fail and flies for nothing !

I speak more about it in my book 'The hot air balloon bible' but it's in french, italian an russian only. Sorry for that, may be I will one day find a sponsor to print it in english. You know translation and print cost the price of a whole very well equipped balloon and afterall, I prefer to fly.

Smooth flights !

I believe you are proposing to somehow fill an envelope with *steam* and make use of the heat given off as it condenses to water vapor (fog). Assuming your number for the heat released at the phase transistion is correct, there seems to be substantial engineering required to build a light weight container for the steam and prevent rapid heat loss. Steam locomotives don't lift off very often!

William W. Plummer a écrit dans le message

True and a a heavy Boeing 747 flies ! )

Don't worry, it's only a smile in reply to your's

You may think what you want but tests have been conducted and all was ok. We can not speak about steam but about warm air which is very different.

I'm not following how you are putting the water saturated warm air in the balloon nor how you are creating it in the first place.

But it is not so difficult to get water saturated warm air until you are in ground and once airborne, you will not need to create it anymore. The balloon enveloppe is of course closed just as it was an helium balloon.

Here is a single idea costing nothing to warm the air but there are many ways.

Construct a tunnel in light transparent pvc. Put it over a black ground surface. Put water in (just as a rain would do, sorry, I do not know the english word for 'asperger ' in french. You know this hand machine you use to kill the bad grass spraying water and product) The sun on the plastic surface will create what we need. It's just like a green house. Blow air in one side of the tunnel and connect the other side to the balloon.

Of course this is a bit experimental but imagine for a big balloon, it will be very easy to collect vapor from pipe cooling coming out any industrial factory. If needed it is also possible to use a burner and vaporize water over it.