Hello,
I'm looking to make a hot air ballon with the arduino, I am trying to figure out what heating source I could use that isn't fire to heat up the hot air ballon.
Thanks in advance! yours truly,
Colin Jeffs
I think you need fire!
How big of a balloon? In terms of electrical energy, I'd guess you need at least 100 Watts for a small balloon. That wouldn't require a car battery, but it might require a motorcycle battery (or a laptop battery) and you'd never get off the ground carrying the battery. You probably have an idea of how much heat a 100W light bulb puts-out. Hair dryers & toasters are more than 1000W. That seems more like the amount of heat you probably need.
You might be able to heat-up the air on the ground and lift the balloon for a short time until it cooled-off.
There are flameless propane heaters, if that meets your "no fire" requirement. But, I'm not sure you'd get the same convection air-flow of the heat into the balloon.
You probably don't need an Arduino. I assume the logic has one input and one output... If the temperature is below X, turn on the heat, or if the altitude is above X, turn off the heat, etc. For example, a regular 'ol thermostat (without a timer) doesn't need a microcontroller, or memory, etc.
You can get some hot air guns that don't have the temperature limits hair dryers do. However they do eat a lot of power. It really depends on size though. I would look at hot air balloon enthusiast sites for alternate hot air sources. The Arduino forums aren't exactly known for their Hot Air Balloon expertise. (I could be wrong though)
Sorry About that, its really small, no bigger then your head. We just want something that will make enough heat for our balloon to rise, We are not worried to much about it flying for a long time, just that it can go for about a min or so
Cheers
Edit: We are welcome to using fire, Expect I don't see how an arduino could do that, and its a school project so we are trying to keep it safe.... if possible
What purpose will the Arduino serve in the hot air balloon?
The tricky part has to be the balance between weight and power, a couple of 18650 batteries wired to nichrome wire could possibly give a minute or so....
What's wrong with a tea light candle?
If you want the heating source to be carried by the balloon, I think you're wasting your time. However, if you want to use a Montpellier style balloon that is held down until it is hot enough and then released, that would be feasible. A balloon suffers from economies of scale though due to the squared/cubed relationship between surface area and volume; the smaller it is, the harder it is to make it fly. Something no bigger than your head will be really difficult and would need your balloon to consist of a soap bubble or similar with no extra structure. So you need to start with the balloon itself, figure out what volume it will be and how much it will weigh, then calculate from that the average air temperature needed inside the balloon for it to float. Once you know what air temperature you're aiming for you need to know what power sources you have available (will it be indoors with access to mains power, or battery powered?) and finally you can design your heating mechanism.
I have no idea of the weight/size/heat ratios...
You need a gas source, a gas valve, a battery, some control circuitry or mechanism, and you'd have to see what you can find that's small & lightweight. Then after determining & minimizing the weight of everything you have to carry, you might have to design the size of the balloon to lift all of this "overhead".
There's an electrically controlled gas valve in every gas furnace. So, it would be no problem electronically controlling the heat (gas flame) in a hot air balloon large enough to carry people. I don't know how small of a gas valve you can find. In an old furnace like I have, there is a pilot light so you don't need any elecectric power to re-light the flame, just enough power to turn on/off the main gas valve. A regualr gas water heater has a thermostat (gas valve) that's purely mechanically heat-operated and it doesn't require any electricity. (But again, its' too big for a toy-size balloon to lift.)
Just to give you an idea, a quick-search turned-up [u]this[/u].
Of course, you'd need a gas source. They make butane lighter refills, and I'd guess that's about the smallest gas source you can find. (Under pressure it's a liquid, so it might be too heavy unless you can transfer it to an even smaller container.)
A friend of mine did this 15 years ago to take aerial photos.
It is a long time ago, and he just showed it an afternoon after we had discussed the subject, but I'll tell what I think I can remember.
A balloon made of plastic bags (I remember it as something like a cubic meter), a simple burner using a coil of thin copper tube to preheat the gas, a homemade valve arrangement and a lighter refill bottle for fuel.
The bottle was upside down, and thus delivered liquid gas that was heated in the coil.
Turning the bottle upright, had given too little gas and problems with ice in the system and cooling of the bottle
It had a pilot light, and I think it was a small wick and some petroleum.
The important part, the valve, is of course something I don't really remember how was made.
Either he had build his own valve, failed, and now used the valve in the gas bottle and a clever cantilever arrangement and a servo..... Or he had failed in using the bottle valve, and had built his own.
If you handle liquid gas, you only need a quite small flow.
He would launch the balloon upwind from his target, use one channel on the RC to control the burner to put the balloon at the desired altitude, then use the other channel on the RC to activate the shutter on the camera.
Once he was on the other side of the target, he would stop heating, and land the balloon for recovery.
And forget about using electrical heating of a hot air balloon.
The energy to weight ratio of batteries is lousy. Burning hydrocarbons is the way to go, when you want lots of heat in a small package.
a simple burner using a coil of thin copper tube to preheat the gas, a homemade valve arrangement and a lighter refill bottle for fuel.
The bottle was upside down, and thus delivered liquid gas that was heated in the coil.
The world is much different today than my elementary days in the late 1950's and school systems are far more cautious on everything.
As this is a school project, maybe you could convince a "Party Shop" to fill a helium balloon for you before class. Two or three medium size balloons could do the trick. In my youth, we would have (and did) do this with hydrogen - it is a miracle I am alive today!
Ray
I've flown lots of hydrogen balloons, and in open air, hydrogen really is not that bad. A bag of hydrogen will not explode, it just burns. And it burns surprisingly slow.
A rubber balloon full of hydrogen will make a rather nice boom and a fireball when ignited, because the bursting balloon mixes the hydrogen with air.
A bag with a stoichiometric mix of hydrogen and oxygen will make a tremendous BANG, especially when ignited at altitude on a frosty winter morning.
In my opinion, weather balloons and the like should be launched with hydrogen.
Using correct procedures, it is no more dangerous than fueling your car.
Helium is expensive and a rather limited non- renewable natural resource that is much better used for cooling our NMR- and MR magnets.
(It is actually quite common to use hydrogen for sounding balloons)
cjdelphi:
The tricky part has to be the balance between weight and power, a couple of 18650 batteries wired to nichrome wire could possibly give a minute or so....
Li-ion has a specified maximum amperage draw. Make sure you don't exceed it or you may end up with a nice fire after all!
As this is a school project, maybe you could convince a "Party Shop" to fill a helium balloon for you before class. Two or three medium size balloons could do the trick. In my youth, we would have (and did) do this with hydrogen - it is a miracle I am alive today!
Yep. If you want Arduino descent control, you can connect a solenoid or ball valve turned with a servo to one of the balloons' openings. You can then release lifting gas as desired, perhaps based on the input of a BMP085 barometer or GPS module (autonomous) or RF interface (ground control).