This thread could go into failblog...
But the idea is intereting. How do you make an umbrella stand upright by itself? I was thinking a little bit about this... and the answer is simple.
You don't need something to balance it out... and who would seriously carry around a liter of water (1KG!) in an umbrella?! Before you make such an invention, you should think about how "comfortable" it will be to use. For sure, i wouldn't buy an umbrella that comes with a 1 liter bottle of soda attached to it...
But as i said, the answer is simple. What you need for an umbrella not to fall over, is a TRIPOD!
You'll need a small tripod, that's not heavy, and is attached to the umbrella. It could look a little something like in the picture i've attached. That's just an idea tho... in the end, it doesn't matter how the mechanism would work exactly. As long as you can "activate" a little tripod on your umbrella, it'll work.
Depending on how big you make the tripod (can't be too big tho), the umbrella will stand more or less stable, but will still be easy to knock over (even a little bit of wind can do that). But basically, it would not tend to fall over by itself anymore.
So there, i saved the day for you lerts, you can stop thinking too hard now, and produce such an umbrella and sell it.
There are only two questions left...
Will you spend more money on producing the umbrella than a new G25 would cost you?
and
Will people buy the umbrella, because a "self standing" umbrella is what they've been waiting for since many years (i certainly wasn't)?
cheers