I am not a qualified engineer or anything like that, just a guy working as Rigging Grip in Broadcast, and we have a Wirecam system. The Sled and camera is powered by batteries, and operates and transmits by radio - a moving trolley/dolly/wagon so to say. We rig 2 ropes for safety, the Sled has a traction motor on the bottom line, and a bracket with pulleywheels for the top line.
Gear is Dactylcam pro 48V /Newton2 gimbal /Sony P50, line is 10mm Dyneema SK99 MBS 7500kg.
* Total weight of sled and camera is approx 44 kgs
* Weight of line is approx 80g/m
* Span can be from 25 to 600 meters, deflection depends on where we can rig our points, and how much force we are allowed to pull.
* We regularly pull up to 500 kgs on each line for a max total of 1 metric tonne. But some arenas and scenarios requires less, or allow less.
* To simplify I have not included the added weight of wirejacks + loadcell on one end, and shackles + slings on both ends. Also for simplicity both anchor points are at the same height, and the camera is in centre where the load is highest.
I have made a spreadsheet to the best of my ability, but I am not experienced with Excel and my education in maths is very slight, also ...three decades ago. To add the forces from the weight of the line to the centre load (in my simple pythagoras), feels wrong to me - as the line is distributed weight, but camera + sled is centre weight. And I am also struggling slightly with getting the math right when adding the second line to the equation, as it then takes half the centre weight. Right?
The spreadsheet has two parts, so I can input either:
* Span length, weight of cam+sled, and allowed deflection – to see how much Pull I need.
* Span length, weight of cam+sled, and pull allowed – to see how much deflection I get.
The weight of the line is not insignificant when the lines get long and the payload is as low as it is. There is also a good chance we will see similar but lighter camera systems later, then maybe we can use a thinner line.
I need help to get the spreadsheet right with what tension the lines get, it would be a big help for quickly finding basic numbers when projecting a job/location. If you can’t or won’t look into the details in the spreadsheet, maybe just put me on the right path to include the maths for the weight of a line in a span. I guess the vector of the resulting force would be interesting too, and how to add this into the spreadsheet to get all the numbers right in the end. I am just not smart enough to figure how to sum the resultant vector forces in the rope, from weight of rope and weight of camera, since the angle increases when you add them up.
I am very sorry for the use kg’s instead of Newtons - but its close enough, and I always add a little to get the margins on the right side of safety. We strive for 10x breaking strength (5T) in all parts,almost there most the time should be; there, almost all of the time 
.
The spreadsheet would normally have all cells locked except for the input fields.
Cheers, Haakon
*minor edits to clear up
Gear is Dactylcam pro 48V /Newton2 gimbal /Sony P50, line is 10mm Dyneema SK99 MBS 7500kg.
* Total weight of sled and camera is approx 44 kgs
* Weight of line is approx 80g/m
* Span can be from 25 to 600 meters, deflection depends on where we can rig our points, and how much force we are allowed to pull.
* We regularly pull up to 500 kgs on each line for a max total of 1 metric tonne. But some arenas and scenarios requires less, or allow less.
* To simplify I have not included the added weight of wirejacks + loadcell on one end, and shackles + slings on both ends. Also for simplicity both anchor points are at the same height, and the camera is in centre where the load is highest.
I have made a spreadsheet to the best of my ability, but I am not experienced with Excel and my education in maths is very slight, also ...three decades ago. To add the forces from the weight of the line to the centre load (in my simple pythagoras), feels wrong to me - as the line is distributed weight, but camera + sled is centre weight. And I am also struggling slightly with getting the math right when adding the second line to the equation, as it then takes half the centre weight. Right?
The spreadsheet has two parts, so I can input either:
* Span length, weight of cam+sled, and allowed deflection – to see how much Pull I need.
* Span length, weight of cam+sled, and pull allowed – to see how much deflection I get.
The weight of the line is not insignificant when the lines get long and the payload is as low as it is. There is also a good chance we will see similar but lighter camera systems later, then maybe we can use a thinner line.
I need help to get the spreadsheet right with what tension the lines get, it would be a big help for quickly finding basic numbers when projecting a job/location. If you can’t or won’t look into the details in the spreadsheet, maybe just put me on the right path to include the maths for the weight of a line in a span. I guess the vector of the resulting force would be interesting too, and how to add this into the spreadsheet to get all the numbers right in the end. I am just not smart enough to figure how to sum the resultant vector forces in the rope, from weight of rope and weight of camera, since the angle increases when you add them up.
I am very sorry for the use kg’s instead of Newtons - but its close enough, and I always add a little to get the margins on the right side of safety. We strive for 10x breaking strength (5T) in all parts,
.The spreadsheet would normally have all cells locked except for the input fields.
Cheers, Haakon
*minor edits to clear up
