Wow, this is one of my favorite engineering questions, wireline rope drum. Be very careful with this one, she's a beast! I crushed about twelve designs before getting it right, almost gave up on it.
You need to determine the wireline load or tension in the windings! This is the trick. You can get that noting horsepower equals the torque times RPM divided by 5252; torque is in "ft lbf" and obviously RPM is in rev per minute. You know the motor horsepower so can easily determine the torque.
This is the trick. In the first layer of windings, assuming you lay the wireline uniform and neatly without gaps, the compression on the core of the drum is simply the hoop stress. In other words, you can determine the pressure exerted by the first layer of windings noting torque and distance from the drum axis to the centre line of the first layer wrapping.
Maintaining the line tensile load, you begin the second layer wrapping. But your moment arm just changed by the diameter of the wire rope being layed. So the second layer does not have the same pressure laid to the core and first layer of windings. You should find that the compressive strength applied to the drum jumps significantly. This phenonema occurs for each successive winding of wire laid upon the layers below.
The required radial compressive strength is the sum of all pressures determined per layer. Also, there is a side load imparted to the flanges of the drum which induces a moment to the core. This is amazing considering each successive wrap of wireline is actually cradled by the layer below. Once you have that estimate, you are pretty much in control of the dynamics of the drum, less thermal expansion of the system, which can be significant.
Look at it like this. Take an elastic and start wrapping it around your finger. Finger turns blue right? That is the core pressure exerted by the elastic tension as it is being wrapped. If you can stand it, try to wrap a second layer. You will feel the pressure on your finger go through the roof! Imagine what the drum is going through using wire rope!
I do recall several excellent references from the industry. I need to pull some files and get the actual model I used to solve this one, but I recall it was a major struggle for me over a two year period. It's not about the money lost in failed designs, it's about my stubborn attitude never to give up. Some of the industry drum guys may be of help, but depending on your application, they are actually of little help. Wire rope industry reference is much better, sometimes limited. There is a welding reference from Lincoln that discusses this problem in detail, that is what I researched years after my experience.
Yup, fun times!
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
I am looking for advice/guidance on how to calculate maximum lifting and maximum holding capacities (preferably in kg) for a drum style winch with the following details. 
