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

A true sign that “you should never go against a robotics kid” – when you triple the school record and there is talk from the school administration that the project will be banned from the school. For physics, we had to construct a catapult that fit within a one meter cube, and launch a base ball. With the help of cad software with stress analysis, the “robotics group” (as everyone called us) designed an arm that could handle 500lbs of force. The previous school record was 55meters. Our catapult group…… 150meters. Naturally, we all wore safety glasses and practiced good safety procedures, however, the school administration is possibly banning the project due to liability concerns. Epic Success!

“You’ll shoot your eye out, kid!”

(yes I watched A Christmas Story recently)

That thing make the most awesome swishing noise when it fires. It was like a knife through air, and was one of the quietest catapult there, though it went the furthest.

It uses a 25/32 inch steel axle and car bearings.

yeah there a big spread in most tech class projects from robotics kids a not yet robotics kids

A video would be awesome (if possible)

I’ve died and gone to surgical tubing heaven.

I have a few videos from testing, but i need to get them on my computer, so i will problably upload them to youtube by the end of the week.

Not to be stickler… ok, yeah, I am:) . That thing looks a lot more like a trebuchet than a catapult. Remember, engineers must always be precise in communication.
Anyway, awesome job! The physics classes at my kids’ school also have a project to build a “device” to launch a tennis ball and hit a target 20 feet away (30 for honors, variable distance for AP, accuracy counts) Requirements were 2’ x 2’ base, no part may extend above 1 meter at any time. last year, one of the classes put a spin on the project and said shoot as far as you can, bonus for more than the minimum distance. One of the robotics kids built a monster device that fired a tennis ball well over 250 feet (tennis balls don’t fly as well as baseballs). Kids are still talking about that catapult.

If you don’t want it banned, you should have the project changed so that the students not only have to go 40-50m but also have to hit a target at that distance. That way the hard physics of calculating and attaining the necessary final speed and launch angle is thrown into the mix while also keeping such a valuable learning project in the curriculum.

This begs the question, ‘Is it better to be famous, or infamous?’

It’s not really a true trebuchet either. Trebuchets use counterweights to throw their payload, this uses surgical tubing. This does appear to use a sling however, which is a staple of trebuchets. IMHO, it still qualifies as a 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.

Also, very slick, makes me wish I had known how to do that sort of thing during high school.

I would suggest to the administration to simply change the projectile. Tennis balls, oranges, and racquetballs are a bit softer. How many projects do schools offer that teaches THIS much and is also fun to do?

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.:wink:

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. :slight_smile:

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.

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!

…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…:smiley:
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:rolleyes:

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


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.

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.

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.