- Location
- South Dakota, USA
Re: Engineering a Tree Removal
Mark, your point is precisely what I wanted to say in my earlier post, so I think we are now on the same page. The total force Figure 4 is definitely more than in Figure 2. It is spread out, as you say, over two branches, so there is less force at any one point in the tree. (Unless you want to start factoring in levers but that is a whole different topic.)
You are correct Glen that the two forces aren't additive. Their magnitudes |F| are however, so perhaps I should clarify myself, and say that the combined magnitude of all forces in the tree is greater in Figure 4 than in Figure 2. You also make a good point about the net force in the tree being pointed straight down. This force is not always directed down the center of the trunk, you show an example of this on your piece of "computation paper". (It is amazing how you drew that so much like mine!
I'm honored to be modeled in such a way.) If this force is directed to one side or the other torque is placed on the entire tree (i.e.: it is pulling it sideways). This could lead to the tree tipping over in the most extreme of cases. I can't imagine this is a *huge* issue but maybe something to consider when speed lining?
To partially sum up what we've mentioned and to add a few items, this is better because:
<ul type="square"> [*]The force at each Rigging point (each block/pulley) is reduced. [*]The force is directed along a branch instead of orthogonal to it. [*]In situations of weak branch unions (included bark, etc) this system can be used to hold the tree together. (Not to be used alone I wouldn't imagine.) [*]More rope is present in the system, so there is less stress on all Equipment involved on initial loading of the system. (Note that this could go several ways, the extra rope means more slack in the system to take up. If this slack is not removed and the rope pre-tensioned, the load (branch) will fall farther before stopping. On the other hand if the forces on each anchor point are now along the length of the branch, they won't move as far and therefore they will have *less* give.) [/list]
Did I miss anything?
Isaac
Mark, your point is precisely what I wanted to say in my earlier post, so I think we are now on the same page. The total force Figure 4 is definitely more than in Figure 2. It is spread out, as you say, over two branches, so there is less force at any one point in the tree. (Unless you want to start factoring in levers but that is a whole different topic.)
You are correct Glen that the two forces aren't additive. Their magnitudes |F| are however, so perhaps I should clarify myself, and say that the combined magnitude of all forces in the tree is greater in Figure 4 than in Figure 2. You also make a good point about the net force in the tree being pointed straight down. This force is not always directed down the center of the trunk, you show an example of this on your piece of "computation paper". (It is amazing how you drew that so much like mine!
I'm honored to be modeled in such a way.) If this force is directed to one side or the other torque is placed on the entire tree (i.e.: it is pulling it sideways). This could lead to the tree tipping over in the most extreme of cases. I can't imagine this is a *huge* issue but maybe something to consider when speed lining?To partially sum up what we've mentioned and to add a few items, this is better because:
<ul type="square"> [*]The force at each Rigging point (each block/pulley) is reduced. [*]The force is directed along a branch instead of orthogonal to it. [*]In situations of weak branch unions (included bark, etc) this system can be used to hold the tree together. (Not to be used alone I wouldn't imagine.) [*]More rope is present in the system, so there is less stress on all Equipment involved on initial loading of the system. (Note that this could go several ways, the extra rope means more slack in the system to take up. If this slack is not removed and the rope pre-tensioned, the load (branch) will fall farther before stopping. On the other hand if the forces on each anchor point are now along the length of the branch, they won't move as far and therefore they will have *less* give.) [/list]
Did I miss anything?
Isaac
