Help scratch building a floodlight with weight restrictions

Hi,
I'm doing a project for a college course that involves me designing a powerful floodlight that can be suspended from a weather balloon. It needs to be around 1Kg, be as powerful as possible and have a battery life as long as possible. Everything including the battery need to be airborne hence the weight limit. I could really use some help with some component suggestions, possible circuit diagrams and anything else useful.
Thanks in advance :thumbsup:

Well, more info is needed.
1st, What's the minimum length of time this light needs to operate?
This will dictate everything else.

The set of requirement is very minimal, offering almost no way to justify any sort of design decisions. It seems that as long as you meet the 1kg limit, any solution is acceptable.

The two criteria, run time and brightness, are inversely proportional to weight. About all you can do is look for the lightest solution or technology for each.

How clever are you allowed to be? The lightest source of electrical power would be a hydrogen fuel cell. The nice thing is that adding fuel reduces weight! This assumes that the hydrogen is allowed to be stored in a balloon.

Well, virtually all the weight will be your power source, whatever that is. For most power sources, run time is inversely proportional to power output. Since brightness should be pretty proportional to power, you arrive immediately at a required decision: how to trade off run time vs. brightness. You'll have to make that decision before much else can be done.

I was all ready to say that hydrogen fuel cell was a real pie-in-the-sky idea, but I googled it and found that you can actually buy one that weighs half a pound for around $100. The watt-hours per kilogram doesn't even approach that of LiPo cells, but you might be able to make it a lot lighter by stripping it down. And if your fuel supply has negative weight, theoretically you can have as much power as you want for as long as you want without exceeding the weight limit. Your design would be limited only by the depth of your pockets.

Still, I'm guessing an idea like that isn't going to fly (LOL), and you'll probably end up using batteries. You'll want the highest energy-to-weight ratio available, which is probably lithium thionyl chloride, zinc-air, or something like that. Both of those have very limited discharge rates, so might not be suitable if you plan to suck them dry in a short time. There's that darned first decision rearing its ugly head again...

Also, if the light needs to be suspended from a weather balloon, is there some minimum target illumination distance? For example, if it'll be a low-flying balloon, are you trying to illuminate land beneath it? If so, at what distance, over how large of an area, and with what brightness? This could give an estimate for the output of the light, which of course will help estimate run times for various ideas.

I'd go for a good wind turbine, winds up there can get fast and a good turbine could keep it powered indefinatley. I suppose its going to need to get brighter as it gets higher?

The balloon would presumably be travelling with the wind, and thus seeing virtually no apparent wind.

Unless the balloon is tethered, in which case it's likely not high enough to get reliable wind.

DIWdiver said:

The balloon would presumably be travelling with the wind, and thus seeing virtually no apparent wind.

Unless the balloon is tethered, in which case it's likely not high enough to get reliable wind.

Click to expand...

Unlikely as its such a big particle, i havnt googled it, but i do not think that baloons such as the ones from japan that dropped bombs on western america in ww2 or the high altitude ballons of ocean crossings.