Center of Gravity - Page 1

Hello Patrishap, You had asked me how to locate the centre of gravity (cg) several days ago. I have been away a few days and I cannot find the thread you asked this on. If you are still interested, request again under this subject. How much do you want to know. A whole book could be written on this subject. ecs

ecs, as an emperienced skydiver (600+ jumps) with a fairly good understanding of Bernoulli's principle and several friends who are commercial pilots, I am fairly well versed on cg issues as they relate to flight. I'd be interested in hearing your thoughts about how this can be applied to dogs.

Keith, I wrote a rather lengthy response but for some reason it did not post. It is my bed time at the moment so I will rewrite it again tomorrow. Forgive me please. Thanks. ecs

Hi ecs and Keith, 600 And still with us Keith - dog jump before or after you? Under Front Assemply, ecs, by way of lines across animal's profile you detailed where longitudinal C of G of animal is located: presumably this is for static condition with animal in a particular pose. In dynamic condition with animal in state of forward movement, I assume it would automatically shift aft. I simply wondered at the proof, reasoning or theory from which the above is derived. I'm also thinking here that no two animals can be exactly the same in construction or lenghtwise weight distribution. And, how may we use knowledge of animal's gravity centre(s) be used in a practical way in analysing an animal's structure or movement.

Keith and Patrishap. I have written a treaties twice for answers to you both. Each time it has not been posted. This typing is a chore for me and I do not think I want to go through this again. ecs

Hello Keith and Patrishap- I am going to try this for the third time. I got an email asking that I respond once again. This time I think I will do it in two or three posts: make a point and then go to another point. Anyhow, bare with me. Keith, I am not a pilot nor do I have much knowledge of Bournelli's Principal. All I know is that the air flow of the top and bottom of a wing of a plane is not the same and that this causes lift. I do not think this will be the case in our dogs...unless our dogs have extremely big ears. I thought I would try and present a couple of experiments regarding the center of gravity. I would ask you to participate by actually doing these experiments. I think you might get a little better understanding of the principals. This will be continued on the next post. ecs

The first experiment is to get a small rectangle of the same consistancy front and back. Mark one end as "Front". Mark each corner as a "foot". Then make a diagonal from left rear to right front, and then one from right rear to left front. Where the diagonals intersect should be the center of the board, the balancing point, or the center of gravity. If you place your finger on this intersection, it should balance. For our dog to be in balance, its center of gravity should not deviate from side to side. Exerte a force on the right rear "foot" and see what happens. The rectangle will move forward but rotate somewhat counter clockwise. Notice the movement of the center of gravity. Now do the same thing with a force on left "foot". Now the rectangle again goes forward but rotates somewhat clockwise. Again notice the path of the center of gravity. Go to next post. ecs

Once again lets perform this experiment watching closely the path of the center of gravity. However, this time let's move our right "foot" in about 3/4 way to the center of the rectangle and then exert the force. Again to the left "foot" which we move inward 3/4 way toward the center of the rectangle. Compare the path of the center of gravity between these last two experiments with the first. It still moves side to side but with less side-ways movement. We can deduce from this that the narrower the force (drive)is to the center the less divergence from the center will the center of gravity move. Thus our GSDs move on a single tracking movement. (This part of the experiment should have come after the next segment, but I am not going to retype all this.) The last part of this experiment is to get a weight and place it in the top right quarter of the raectangle. Place a force on the right "foot" and observe the action. Repeat the action with the force on the left "foot" but do not remove the weight from the right front quarter. Observe the differences in the the center of gravity between the two versions. The weight cause the center of gravity to move toward that weight. (More on the next post.)

Continuing the experiments- The last experiment we will try is as follows. Get a large weight of approximately 25 pounds. Place the weight on your shoulders and take a few steps. Now hold the weight close to your chest and take the steps again. Finally, hold the 25 pound weight at arms length and take the steps again. In each case it becomes more difficult and tiring as we take the steps. Holding the weight at arms length will be much more difficult. Considering the weight as the center of gravity, it is easy to see that the closer we maintain the center of gravity close to the center of the body, the more endurance we have and less tiring our walk becomes. We desire our GSDs to be a dog of endurance. That was what he was bred to do and is what we wish to maintain. Keeping the center of gravity relatively stable helps to emplement this stability. There is one more experiment we can show that has an effect on the center of gravity, but we aren't do it. We will discuss it a little in the next post. ecs

The final example of the Center of Gravity We know that the dog creates some lift in his drive as does the front assembly to some extent. This in essence creates an up and down movement in the center of gravity. Thus, our center of gravity has four motions, left, right, up and down. As said earlier, our purpose is to keep this center of gravity as stable as we can for better endurance. As the breed begins to change, breeders will take steps to get the dog back in harmony. There are several ways to make these changes. Usually, I think, these changes will be made by the kennels who have the problems. As their problems manifests themselves, the breeder will take the appropriate action. Some of these remedies are bigger heads, longer necks, larger muscles, larger or smaller bones, longer or shorter croups, more or less angulation, and others I have given you some basic principals on the central of gravity. Not knowing your degree of expertise, I have hit the high lights. Should you have any specific questions, feel free to ask. But as for me, I am now going to bed. ecs