Baseball payload; or - place a ball on a spire with a blimp?!

[Artemetra]

In my town there is a marvellous ball field, home of the local minor league baseball team. The field has 4 spectacular, very pointy spires - parts of the architecture. Kind of behind home plate are two of them, and they are about 80 feet from the ground to their tips. Now every game, about a half dozen fouls get sent out of the park over those spires...

My plan is to place a baseball on one of them - as a practical joke, which will be tough for them to get off - I'll be immortalized for at least a half season, I figure... I have the baseball with a hole, and it weighs ~5 ounces or about 140 grams. Previously, I plotted to get helium balloons, 3 helpers, and a string-rig with a tear-away funnel guide to get the ball up there. Now I'm thinking BLIMP, or hovering balloon platform, with three motors and R/C. The question is, how do I figure the payload of helium? Other questions will follow, like what configuration, batteries, and is there such a thing as hands-off head wearable binoculars?

-Plotting my midnight mission,

artemetra

[Majortomski]

Rule of thumb, one cubic yard of helium 27 cu ft will lift one pound of load. My blimps could lift it the problem is it would have to be a dead calm night. Why not solve the alignment problem with an on board camera?

[Artemetra]

Rule of thumb, one cubic yard of helium 27 cu ft will lift one pound of load. My blimps could lift it the problem is it would have to be a dead calm night. Why not solve the alignment problem with an on board camera?

Good start - thanks for the info. Now I can start weight calculations. I wonder about a suspended motion body - maybe a fan for lift and one for forward/aft-side/side, with servos on vanes. Or maybe back to gimbal-mounted blimp pods.

I'm keen on a wireless camera outfit, (have wanted to do this for airplanes), but it could get overwhelming quickly. I've also got to figure a release servo and mechanism.

[Iepurila]

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[Artemetra]

I think it's better: 1 mol of any gas takes 22.41l. 1 mol of helium weights 4g. 1 mol of air is 0.8 mol of nitrogen and 0.2 mol of oxygen and weights 0.8 * 28 + 0.2 * 32 = 28.8g. The difference is the lift capacity, for helium 24.8g per mol. So 22.41l of helium lift 24.8g. 1 yard = 0.9144m, so 1 cubic yard = 0.765 cubic meters = 765l = 22.41l * 34.12. So 1 cubic yard will lift 34.12 * 24.8g = 846g. 1 pound = 453.6g so 1 cubic yard should lift about 1.87 pounds.
If you use hydrogen (2g/mol), 1 cubic yard should lift 2 pounds.
If you use methane (16g/mol), 1 cubic yard should lift only 0.96 pounds

Now you're getting all technical on my &##! I'm still working on (4/3 pi r^3) so I know what size balloon(s) to get.

I am also practicing helicopters on the sim, but I realize that I'm not going to be doing it with a heli. WAY too "flighty." In fact, I'm back to wondering about guys holding strings hooked to the balloons.

[Iepurila]

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