How to build a counterweight catapult,create and host your own website free,timber sheds for sale melbourne suburbs,arrow storage sheds 10 x 9 online - PDF 2016
The remote operated counterweight system allows for the hatch to be raised and lowered without needing to enter the kennel.
I didn't notice this before, but the line between the front two dome slices is just a mm or two off center. So I'm going to attempt to do the ears according to rafalfett's technique, but I don't have any 1 mm cardboard so we will see how it goes. Problem: I forgot to cut out the slot for the Honeywell micro switch before gluing all the pieces together. I can't for the life of me figure out how to cut out decent circles from this chipboard, so it looks a little rough.
I want to do a clear Perspex block, but I don't know whether I'll be able to make it or just buy one.
Catapult physics is basically the use of stored energy to hurl a projectile (the payload), without the use of an explosive.
Among the various types of catapults, the trebuchet was the most accurate and among the most efficient in terms of transferring the stored energy to the projectile. A trebuchet works by using the energy of a falling (and hinged) counterweight to launch a projectile (the payload), using mechanical advantage to achieve a high launch speed.
In some designs a guide chute is used to guide the sling along and support the payload until the speed is great enough to hold it in the pouch alone. As you can see, the counterweight pivots around a much shorter distance than the payload end.
As the beam rotates clockwise (due to the falling counterweight), the payload experiences centripetal acceleration which causes it to move outwards (since it is unrestrained). The above picture of the mangonel is what people are most familiar with when they think of catapults. The mangonel was best suited for launching projectiles at lower angles to the horizontal, which was useful for destroying walls, as opposed to the trebuchet which was well suited for launching projectiles over walls.
However, the mangonel is not as energy efficient as the trebuchet for the main reason that the arm reaches a high speed during the launch.
The physics behind a mangonel is basically the use of an energy storage mechanism to rotate the arm. The figure below illustrates a mangonel in which the energy source is a bent cantilever, which is a form of tension device.
The point P in the figure is the pivot axle, attached to the frame, about which the arm rotates. The other type of energy storage mechanism is a torsion device, which can consist of twisted rope. The fact that a mangonel uses an energy storage device that consists of a deforming material, like wood or rope, means that its throwing distance will not be as consistent as a trebuchet.
If you're interested in having a small working Da Vinci catapult you can get one through Amazon. The onager catapult is almost identical to the trebuchet, but instead of a falling counterweight, it uses a torsion bundle to rotate the arm (similar to the mangonel, described previously).
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Charlie, Frank, Donny, Keith and anybody else I didn't mention thanks for all of your input as well!
Additionally, I was thinking of making a new topic about this, but I'm not sure of the forum rules and I don't want to impose.
It's surprising how many dump truck loads of dirt are removed from a road side ditch when it's cleaned out.
The road crews have to haul and dump it somewhere and are willing to give it to you especially if it's a short haul from where they're working. This is particularly useful when housing boisterous or dangerous dogs as they can be restricted to either part of the kennel, allowing access into the required area without coming into contact with the animal. It did go relatively painlessly because of the terrible experience I had with this on my last build. So when I put the arrows in, they look a little off center, but they are centered compared to the t-visor center line. Doing the ears this way is significantly more labor-intensive (having to cut out all of the little supports) but it seems to be more sturdy, lightweight, and in my opinion looks cleaner.
I'm about halfway through cutting out the 30+ supports for the left ear so I'll do a short update on that tomorrow. The payload could be thrown a far distance and do considerable damage, either by smashing down walls or striking the enemy while inside their stronghold.
In addition, it allowed greater consistency in the throws due to the fact that the same amount of energy could be delivered every time, by way of a raised counterweight.
For maximum launch speed the counterweight must be much heavier than the payload, since this means that it will "fall" quickly. The advantage of this is that the payload end of the beam reaches a much higher linear velocity than the counterweight end of the beam.
At this point the ring (which is connected to the sling and loops around the finger for support) slips off and the payload is launched. This results in a large increase in linear velocity of the payload which far exceeds that of the end of the beam to which the sling is attached.
This means that a large percentage of the stored energy goes into accelerating the arm, which is energy wasted.
This is because these materials (unlike more modern materials), naturally wear and lose elasticity during their use. Because of its design, it allowed for greater throwing distance than the mangonel (comparable to that of a trebuchet). The catapult has proven to be a very effective weapon during ancient times, capable of inflicting great damage.
This is the principal of mechanical advantage, and is what allows the payload to reach a high launch velocity.
This is the heart of the physics behind a trebuchet and is the reason why a trebuchet has such great launching power. This is unavoidable however, since the payload can only be launched at high speed if the arm is rotating at high speed. It consists of either a tension device or a torsion device which is directly connected to the arm. This is something that needs to be constantly monitored during a battle, with replacement materials made readily available, if necessary. But the throwing distance wasn't as consistent as the trebuchet since it relied on deformable materials as the energy source, which naturally wear and lose elasticity during their use. The picture above shows the torsion mechanism consisting of twisted rope, located at the pivot location of the two side arms.
However, because the counterweight pivots around a much shorter distance, its weight must be much greater than the weight of the payload, to get a high launch velocity. Upon release, the arm rotates at a high speed and throws the payload out of the bucket, towards the target. So the only way to waste as little energy as possible is to make the arm and bucket as light as possible, while still being strong enough to resist the forces experienced during launch. These types of catapults will be described, and pictures and illustrations will be included. However, increasing the mass of the counterweight beyond a certain point will not help, since the limiting speed of the falling counterweight is free-fall speed. Our cranes have been successfully supplied to customers in the offshore Oil and Gas industry in the UK on the basis.
This crossbar is positioned so as to stop the arm at the desired angle which results in the payload being launched out of the bucket at the desired launch angle.
Adding that counterweight to my 660 made it 'feel' like ps after moving clay with it all day, the day before..
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