Strength of steel question

[richard]

Whilst pounding the pavement on 18 wheels I came up with a little gadget purely as a fantasy thing. Picture something like a high steel construction crane but on a smaller scale. My gadget will be centered around a simple pillar in the middle of a huge parking lot. So that the single arm swivels 360 degrees about the pillar. The arm would reach out say like a 1,000 feet at the maximum point and be retractable.Or perhaps have a "chair" movable about it. The only thing it would hold would be something like a movie director's chair as seen on some pivoting cameras. Got the idea? Ok so the question is, what size steel beam would I need to extend to 1,000 feet? Keeping in mind that weight on the beam would probably be less than

1,000 pounds at all times. Would pipe work better and have the "chair" inside a channel thing? Purely fictional of course. The main support pillar could also be placed beside a building. It would not have to be in the center of the lot.

[RicodJour]

Forget about the weight of a beam, and concentrate on the load itself. You're essentially building a big balance beam. The load at the end of that 1000' arm would be about four or five hundred pounds (guy in chair with camera) > 500# x 1000' = 500,000 ft-lbs. If you had a counterbalance on the other end of that beam, say 10' from the fulcrum, you'd need a 25 ton weight to balance. When you factor in the beam weight, the load would possibly be an order of magnitude greater.

You're just looking to design a crane and there are no new inventions in lifting loads. It's all been done. So base your design on an existing crane design and just lighten up the structure and load. Like this:

Use a large factor of safety.

R

[Deputy Dumbya Dawg]

What about the cable suspended sky-cam's they use at football games? dawg

[Steve Barker]

what about 'em?

[John Reddy]

Those are on cables suspended across the stadium.

Cameras on cranes are used at golf tournaments on a regular basis but none of them are on anything like a 1000' swing arm like you're talking about.