John H. Trebuchet and Research

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John's Trebuchet

Another web visitor (An Engineering Student) has used my trebuchet making tutorial to make himself a treb and it came out great. He has also made some design improvement which I will point out to you. And he has done some research on the subject of trebuchets and the engineering of them that will help you a lot if you want to make a more powerful and more effective trebuchet! Here are a couple of pictures of his treb. Thanks to John H. for his great work and the phenomenal research he has done! Great job John!

Some fast and important points you need to know:

John Points out that the best ratio of counterweight to projectile is 133 to 1 so try to get your counterweight to weigh 133 times that of your projectile!
Maximum range is attained when the projectile is released between 40 and 45 degrees.

Side view of the Trebuchet The arm in vertical positon, also has wheels

Some specifics about his Trebuchet:

He added Wheels to his design (You can see the wheels in the picture on the right). They give it a battlefield ready look and they added 25% more power! With the wheels on it this thing looks like it is ready to be rolled out on the battlefield. (The wheels add more power because as the counterweight falls the whole machine moves forward slightly to "meet" the fall thus giving you a more vertical drop leading to more energy being transferred to the throwing arm).
He added the locking Mechanism that Koji Suggested with his Trebuchet. Koji's treb suggestion
Beefed up the frame by using 1" x 2" pine stock
The counterweight is 1.25 Kg and the projectile is 10 grams (This gives him a near optimal performance of 125:1 and optimal is considered to be 133:1 so he is very close!)
His counterweight is a container with 7 rolls of pennies and some lead shot. (to get 1.25 kg)
His favorite projectile is a hardened ball of playdoh!
The axle is a piece of stout welding rod which is perfect!
The Coat of arms he put on his treb is his actual family crest! Nice!

John has written a presentation on Trebuchets and Transfer of Energy. It has a lot of great information that will be useful to you if you are thinking about making a treb. This is copyright© 2008 John Hall - All Rights Reserved (Thanks John!)

Individual Project
Transfer of Energy

John Hall

History

The trebuchet (O. Fr. - "to overthrow") was a vast improvement on the catapult design in that it used a counterweight and fulcrum to power its throwing arm as opposed to earlier technology which used torsion power by way of twisted rope or sinew. Not only was the trebuchet more powerful than its predecessors, accuracy was improved as well. A catapult had a fixed power, meaning that the entire machine had to be moved to adjust the range. The trebuchet's range could be adjusted simply by adding to or subtracting from the mass of the counterweight. The biggest and most powerful trebuchet ever made, Warwolf , stood over 4 stories tall, weighed 30 tons, had a throwing arm 50 ft. long with a 20 ton counterweight, and could hurl a 300 lb. stone a distance of 900 ft.

Lesser Known History

Said to have been invented by the Chinese in the 5th century BC, the trebuchet is best known from its use throughout Europe between the 12 th and 15 th centuries before the advent of gunpowder rendered them obsolete.
Some of the more ruthless besiegers (namely Genghis Khan) got very creative in their choice of projectiles, some of which included casks of burning tar, dung, bodies of Plague victims, beehives, baskets of snakes and scorpions, quicklime, unlucky prisoners-of-war, and even emissaries bearing unsatisfactory peace terms.
Cortez tried using a trebuchet against the Aztecs as late as 1521, but the very first shot released at an angle of 90 degrees, which led to disaster for the machine and crew.

How it works

To attain the optimum amount of the transfer of energy the counterweight should be allowed to fall as vertically as possible to gain the most momentum from g (9.80 m/s squared).
To attain maximum range the release point should be between 40 and 45 degrees.
To gain more velocity (of course at the cost of distance) a lighter projectile will have a later release point and a flatter trajectory and thus more speed. The angle of the release hook may also be adjusted forward to attain the same result with a heavier projectile.
Why the wheels add energy: The wheels add more power because as the counterweight falls the whole machine moves forward slightly to "meet" the fall thus giving you a more vertical drop leading to more energy being transferred to the throwing arm.

Experimental Data

The maximum range ballast/projectile weight ratio is 133:1 (2000 kg./15 kg.). Interestingly, Warwolf had the exact same ratio (40,000 lbs./300 lbs.). My model has a ratio of 125:1 (1.25 kg./10 g.).

CATAPULT AND TREBUCHET KITS

Catapult Kit Lay Siege To The Doghouse! Right after you build your own working medieval catapult. All you'll need is glue, scissors and a steady hand to construct this wooden, Canadian-made siege engine kit. The finished catapult stands 6" tall x 5" wide x 10" long and will toss assorted stuff (meatballs?) 15 feet or further, depending upon the stuff. Comes with detailed instructions.

The Desktop Onager: An Awesome all Wood and Twine War Machine - Fiercely Fend Off Office Rivals -- Conveniently sized to sit on your desk, this intimidating little machine is an actual working reproduction of an onager. -- The weapon is all wood and twine with no metal parts, but it packs a big punch. Load it up with the included wooden balls or get creative with marshmallows, coffee creamers, erasers and more to see how many cubicles they can soar above before landing. -- Properly constructed, the onager has a range from 10 to 20 feet. The ancients were able to use nothing but wood and ropes to build machines that could hurl heavy stones great distances, now you can do the same to enforce peace in your office or dorm room. -- Build it yourself in under three hours, because this kit includes everything you need except for glue and a few simple tools like scissors, sandpaper, and a file. Colors may vary. -- Warning: This is a representative model of a real ancient military weapon. Use only with competent adult supervision.

Desktop Trebuchet Defend your desktop! The mere presence of this striking machine on your desk will induce fear and respect among your peers. Take charge and besiege your opponents with a fully functional, genuine trebuchet for your desk! It really works! It takes about two to four hours to assemble, which is a joy in itself with the hand selected wood and computer-controlled, precision cut parts. The professionally designed kit and fully detailed instructions - 10 pages of descriptions and tips, with of photos of every step - makes assembly a breeze. All you really need is some glue and a pair of scissors. For a more refined look, a little sandpaper and a small, round file would be helpful, but are entirely optional. Performance! This mighty desktop artillery is capable of hurling the wooden ball projectiles (included) over twenty feet! Just load-up the counterweight bucket with about 150 pennies and you are ready to go!

The Miniature Trebuchet - The trebuchet was the ultimate artillery weapon of the medieval period and early renaissance. A large and unwieldy weapon, it was typically built on-site during battle, and tuned to lob great weights - such as the carcasses of rotting horses and pots of burning pitch, over the castle walls and onto its inhabitants. This is our newest and smallest trebuchet design in a long line of catapult kits. Designed by master trebuchet expert Ron Toms, this machine is ideal for the student on a budget or as a wonderful display piece for any desktop or bookshelf of any history enthusiast. Precision carved by computer controlled machinery for guaranteed fit and accurate joinery. The detailed instructions include loads of photos of each step of the construction process, tuning tips and safety notes. Included in the kit are four wooden projectiles, all the necessary components for the sling, trigger, and counterweight bucket as well as all the parts for the kit. The only thing you'll need to supply are 64 pennies for counterweight and a few simple tools - Scissors, a ruler, a utility knife, wood glue and a few rubber bands to hold the pieces together while the glue dries. Tools required: Scissors, Glue, Ruler, rubber bands and a utility knife. Sandpaper is optional. Additional Counterweight Required: 64 pennies. Range: About 10 feet.

Science experiment Catapult Kit Science Project Experiment Catapult Kit (S.P.E.C.K.)

The Ultimate Science Project Experimenter's Catapult Kit! It's fully adjustable, multi-configurable and repeatable. It's a perfect model for learning the scientific method! All in all, there are more than 400 different configurations and tuning options possible with this kit. Suitable for hundreds of experiments and learning opportunities. The completed frame is 14.5 inches long, 7 inches wide and 11 inches tall. The arm measures 20.25 inches long with multiple axle and power attachment points. This machine can hurl projectiles up to 40 feet, depending on configuration, tuning, and lots of other variables! What you can learn: This kit provides a real world, hands on example of many aspects of basic physics. It exposes the student to concepts of mechanical advantage, levers, gravity and energy, to name a few. It can demonstrate the storage and conversion of potential energy to kinetic energy through levers, and it is equipped with optional wheels, to demonstrate conservation of momentum. All in all, the concepts of efficiency, power and work can be demonstrated and applied. This kit is useful for teaching engineering, science, design of experiments, problem solving and cause-effect relationships. It was designed to get students to think about physics in a real world, tangible context. Theories can be made and tested; this process, and analyzing why the observed results occur can ultimately lead to other, more advanced concepts in physics, mechanics and mathematics. Analyzing the data can make use of statistical methods from basic averages to much more advanced topics if desired. With 18 pages of instructions including assembly of every basic configuration, suggested experiments, tuning guidelines, independent and dependent variables to record and measure, data tables, historical information about trebuchets and catapults, and more, it should be easy to get started with this Ultimate Science Project Kit!

Ballista Wood Kit - A fifteenth-century military engine used for hurling heavy weapons and rocks. Made from high quality knot free Basswood, this Ballista is a great addition to any homemade artillery collection. Inspired by Alexander the Great's Artillery of the Macedonian Soldiers, this ballistic firing machine is a working model easily assembled from pre-cut and pre-drilled pieces. Includes laser cut plywood wheels. A fun group or family project, once completed you and your friends and family will be experiencing the thrill of flinging projectiles like those medieval machines, but focusing on height, velocity, and distance rather than on knocking down the enemys fortress. For the truely daring, you can alter characteristics of the trebuchet such as the mass of the clay, the string length, or the amount of the counterweight and can see how the results are affected. You will also see these concepts in action: levers, inertia, counterweights, friction, and more. This kit includes all materials for construction -- Size: 11-1/2" long, 9" wide, and 5-1/2" tall. Ages 16 and up, 10-16 with adult supervision.

UBERPULT

You've never seen such cool flinging fun! Designing and building your own unique catapult tops the list of awesome kid inventions! Build a working catapult with 90 pieces and have 91 pieces left to upgrade and experiment with! Part of our Science Project Series; this kit will teach you the fundamentals of a real catapult and allow you to upgrade and improve the performance through a series of suggested experiments in the lab sheet. Don't be surprised when you learn some basic physics principles along the way!

Ballista Wood Kit

Made from high quality knot free Basswood, this Ballista is a great addition to any homemade artillery collection. Inspired by Alexander the Great's Artillery of the Macedonian Soldiers, this ballistic firing machine is a working model easily assembled from pre-cut and pre-drilled pieces. Includes laser cut plywood wheels. -- Size: 11-1/2" long, 9" wide, and 5-1/2" tall

This is a Storm The Castle Project