Site hosted by Build your free website today!

The Trebuchet Page

Pictures are courtesy of  Usa-Kusa

The Trebuchet Page  Akronalpult  Pics

Poll and Feed back Message Board

The Office Warriors  Vid Shots  David's Sling


    These are the message that were left on the message board, that the writer gave me permission to publish.


Message #1:



     "I'm building my own trebuchet for a school project but am having a heck of a time finding actual plans for one. I need one that uses a free weight and one that uses a fixed weight. Please help is possible somehow!!!"

Trebuchetguy: Most designers do not actually create individual plans for there creations. If is a small one my best advice is to design one yourself!  Start small, look around the net for the general idea and add your own slant on it.  Draw it out on paper first. After it is built I suggest modifying it for a superior engineering. Record your results in a log of some kind, and take your observations into account when you build your next one. It is a long but enjoyable process, and well worth it in the end. If you need more detailed help feel free to write back. 


Message #2:

"Joe Bargnesi"


    "My counterweight is malfunctioning. I have attempted to increase the pull factor, but to no avail. Please help me with my situation.

Trebuchetguy: I would like to know this, how can a counterweight malfunction? It is just a object with a large mass that falls to the ground by the force of gravity. Write back and tell me how.


Message #3:

"Joe B",


"Well, like I said, I'm trying to increase the pull factor on my latest treb. this monster is a 50-foot deal that cost me $2000 in building supplies. So, I'm now looking for a substantial counterwieght that can launch huge objects, such as an old car frame i came across. I reinforced the launch shaft with stipulated rivets, so I'm not too concerned about breakage there. In order to launch an object this massive (don't worry, its not a standard car frame... its about half the length of a standard auto... I got it from a Berlin based comany's parts auction. they call em ""coffin cars"" over there)
the counterwieght would have to be immense, and a 70-pound section of crushed metal hasn't seemed to do the job on my heavier projectiles. Anyway, my main concern is the connection trestles I used for my sidebars. I can't dismantle the trebuchet in order to reinforce them, because I don't have the proper tools to do so. One way you could help me is my recomending the proper tool I should rent for the removal of 12-by-2.3 inch tensile-modified rail spikes from my beams. They're 14x12x66 trestles, the kind used for weather-resistant roofs. You may not do projects on this level, so if this is the case, here's my other problem. I've used the PPSI formula to make sure that I could use a counterwieght of 90 lbs to launch a 100 pound payload, but my German car is 128. That would be my second crowning acievement (first being the treb construction itself) and I can't give it up when I've come this far. Anyway, I reinforced the launch bar with the stipulated rivets that I told you about in hopes that it can provide the extra strength, but I can't bring myself to attempt the launch for fear that it will break. I've become very narcissistic because of that treb, and if it snaps, I'll never live it down. So, theres two ways I think you can help. Most of the rookie treb-builders have no idea what I'm talking about when I say this, but you seem to know your stuff. There are two formulas I could use. The first is pretty obscure, but I know it exists somewhere. I'm looking for the formula on density in relation to strength, when the material is reinforced with reinforcements of a known strength. It does have a name, I believe it's the density reinforcement gradient formula. The second one would probably be more difficult to find, because my sidebar trestles are in a strange thickness:length ratio. So, if you could give me the formula for maximum sidebar resistance to carrying wieght for bars that are in a 14x12x66 (7:6:33... I told you it was weird... Japanese trestles, that explains it) configuration?
Thanks alot, Trebuchet guy!
-Joe Bargnesi
PS.. please post this on your message board. Although long, I hope that your readers can help me with my dilemma as well. Thank you~~~~",

Catapult Calypso!:

I'm Catapult Calypso, hired by trebuchetguy to answer complex questions such as those that you have.  Being a professional in this category, I will explain everything! Your PPSI formula off scale and needs more description. I cannot do anything with the current information given to me. The total density of the counterweight should consist of lead-bromide formula. (PbBr). This should work quite well under great pressure. Were talking about 500 Torr. You could order such heavy amounts of PbBr at They have everything you need! In the future please be more specific about your "dilemmas" and don't beg to be put on my web, you're just askin for trouble!

                      -Catapult Calypso- (professional nuclear physic)


A big piece of metal usually works unless you are building a traction trebuchet.