pic: "You should never go against a robotics kid"

[martin417]

Originally Posted by Andrew Schreiber

http://en.wikipedia.org/wiki/Catapult

Nope, its a catapult but at the same time it is a trebuchet as well. Think quadrilateral -> square. Catapult is the generic term.

I would argue it is a trebuchet because it is essentially using the tubing to act as a weight.

OK if we go with the Webster definition of catapult "an ancient military device for hurling missiles", then yes all trebuchets are catapults (but obviously not all catapults are trebuchets). That would then mean that all missile throwers are catapults, including ballistae, onangers, mangonels, and even more modern weapons like howitzers, cannons, rifles, pistols, magnetic rail guns, FA/18 jet fighter...... All of these devices hurl missiiles. (though not all could be classified as ancient).

But if we look at Webster's definition of Trebuchet "a medieval military engine for hurling heavy missiles (as rocks)" there is little difference. It would appear as though the two devices are the same. I attribute this discrepancy to laziness on the part of Webster. I still think a catapult refers to the traditional definition of on arm with a basket on the end that rotates about a pivot until it hits a stop, thereby propelling a projectile forward.

But I have been told to sit down and shut up before, I expect I will be again.

[Andrew Schreiber]

I wouldn't tell you to sit down or shut up, clear concise communication is important and using the correct word can often make things much easier.

Though, I think your definition of a catapult is more accurately a Mangonel or an Onager. I believe the typical view of a catapult is one of those two. From some quick reading I think the main difference between the various catapults was the trajectory they launch their projectiles at. A trebuchet had a very high trajectory whereas a Mangonel had a low trajectory.

Sorry to be getting so off topic. Im a huge history nut.

[Carlee10]

I just got done with one of those....we were outside in the rain, then later snow, at midnight the night before, changing the entire throwing arm,trying to figure out how to attach the weights, and how to trigger it with a mousetrap. We had to shoot a golfball, and we had to shoot it 4 meters or more to get the full points, and we had to trigger it with a moustrap.

I like building things, but this was terrible!!!! We actually got our total grade back today, and we had a C- overall, out of the 200 points. It was 10%of our grade, too. I was kind of upset, and our technical report is actually where we lost most of our points...

Yours looks pretty good. We had to have a theme, too. Ours was "Jankapoult";we had caution tape all around it, too, partly as a joke, but partly because we really didn't know how safe it was and our teacher is 8 months pregenat!

[BlackBird11891]

My Gift to u

yes i am trying to make it

[Eugene Fang]

Originally Posted by BlackBird11891

My Gift to u

yes i am trying to make it

Nice work on the CAD so far.

Just FYI, the vertical posts that are in the actual picture but not in the CAD is a safety feature added later in the design process. After the arm is pulled back, a bar goes through the two holes in the two upright bars. This is so that so while someone is hooking up the quick release, if the people holding the arm back accidentally let go, it won't do a full swing.

[samir13k]

...3 kids from 1501 (non-school sponsored team) were finally allowed to be in a group together in our schools engineering class. It was the first time the teacher let us choose our own groups. It was 1 mechanical, 1 electrical (me), and 1 design student. The task was to demonstrate a usage of pneumatics. We could recreate something using paper, or any other building material. So while most kids used the manual valves, Our group was the first in the classes history to actually use the solenoids in the kit. We did not have a programmer, but i managed to figure it out in a couple of minutes...
Anyways, while most people made something simple like the outriggers on a bulldozer, our group made a pneumatic claw! It was massive compared to all the other projects, used more solenoids than our last 3 bots combined...and used 2 controllers because the schools could only handle 4 motors/solenoids a piece. It could pinch. move outward/inward, and tilt up and down. I will try to remember to snap a pic of it tomorrow... If you can see it lol, its made out of awesome clear plexiglass

[dtengineering]

Technically the lack of a counterweight does not disqualify this as being a trebuchet... rather it puts it in to the category of the traction trebuchet. http://members.iinet.net.au/~rmine/htt/htt02.html

Jason

[ComradeNikolai]

First, however we define what this creation is, it is wickedly cool. I wish I had a class like the one you built that in... and team members to build it with.

Originally Posted by martin417

OK if we go with the Webster definition of catapult "an ancient military device for hurling missiles", then yes all trebuchets are catapults (but obviously not all catapults are trebuchets). That would then mean that all missile throwers are catapults, including ballistae, onangers, mangonels, and even more modern weapons like howitzers, cannons, rifles, pistols, magnetic rail guns, FA/18 jet fighter...... All of these devices hurl missiiles. (though not all could be classified as ancient).

But if we look at Webster's definition of Trebuchet "a medieval military engine for hurling heavy missiles (as rocks)" there is little difference. It would appear as though the two devices are the same. I attribute this discrepancy to laziness on the part of Webster. I still think a catapult refers to the traditional definition of on arm with a basket on the end that rotates about a pivot until it hits a stop, thereby propelling a projectile forward.

I believe these definitions are far too vague to get a good definition (just as I would never define "justice" by a Webster definition; it's good for a quick reference, but for anything remotely technical, it is lacking). For the sake of rapid research, I'm going to use Wikipedia's definitions:

Catapult is defined as "any one of a number of non-handheld mechanical devices used to throw a projectile a great distance without the aid of an explosive substance;" this invalidates the examples of Howitzers and does include ballistae; originally, catapults referred to "ballistae" and ballistae referred to "catapults;" the definitions switched, but it can apply to either as long as it does not use explosives.
This is an example of a catapult.

Trebuchet includes the following: "trebuchet is often confused with the earlier and less powerful torsion engines. The main difference is that a torsion engine [ie mangonel or ballista] uses a twisted rope or twine to provide power, whereas a trebuchet uses a counterweight" and it continues to state "A trebuchet also has a sling holding the projectile, and a means for releasing it at the right moment for maximum range." and "Both trebuchets and torsion engines are classified under the generic term 'catapult,'."
This would appear to be a torsion engine, or a "torsion trebuchet;" however, that is not the normal context of the term "trebuchet."

I would argue that this is a torsion engine but not a trebuchet, for a trebuchet uses a counterweight, whereas the surgical tubing more closely matches the twisted rope used to power many catapults, such as mangonels and onagers.

I apologize for the length of this post, but I love both debate and medieval weaponry... This is not a confrontational post, it is just my viewpoint on it.

[ATannahill]

You're fighting over whether this is a catapult or a trebuchet? I feel you time and effort is being used as well as if it went towards the game hint.

[martin417]

Originally Posted by rtfgnow

You're fighting over whether this is a catapult or a trebuchet? I feel you time and effort is being used as well as if it went towards the game hint.

Game hint? you mean the picture of a fish? The one that has a topic with over 700 posts discussing a picture of a fish? what else can be said about a picture of a fish that hasn't already been said? This catpult / traction trebuchet is a whole lot cooler, and is much more interesting.

[samir13k]

the trebuchet is probably also more relevant to the game then the fish also

[EricH]

Originally Posted by samir13k

the trebuchet is probably also more relevant to the game then the fish also

Catapult/trebuchet/launcher throws the fish across how far???

Hey, could you guys find an opah and launch it, just to relieve everyone's stress around here (and discussion of the game hint)?

[gorrilla]

how did you make it realease on end of the sling at the right time? or was it just try-bend?

[Eugene Fang]

Originally Posted by gorrilla

how did you make it realease on end of the sling at the right time? or was it just try-bend?

If you look closely at the picture on the right (the CAD does not have it) there is a piece of 1/4" aluminum coplanar to the main arm that has a slight V shape cut out. The release angle wasn't perfect (was about 35 degrees I think) but it was good enough. And since it was luck that it went at that angle on the first try, the group decided to just keep it that way.

[dtengineering]

Originally Posted by rtfgnow

You're fighting over whether this is a catapult or a trebuchet? I feel you time and effort is being used as well as if it went towards the game hint.

First of all, I don't think anyone is "fighting" over anything. There is a polite, rational discussion going on as to the appropriate terminology to use when referring to this design. Precision with words is equally as important as precision in drawings, or in machining. Often it is more important!

But I do appreciate the humour in the statement.

Jason