Note: See also the files: crossbows-msg, p-archery-msg, archery-books-msg, c-archery-msg, crossbow-faq, arch-books-faq, pottery-wepns-msg, slings-msg
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| siege-engines-msg – 1/10/08
Catapults, trebuchets. Period and modern. Tabletop models. NOTE: See also the files: crossbows-msg, p-archery-msg, archery-books-msg, c-archery-msg, crossbow-FAQ, arch-books-FAQ, pottery-wepns-msg, slings-msg. ************************************************************************ NOTICE -
This file is part of a collection of files called Stefan's Florilegium. These files are available on the Internet at: http://www.florilegium.org I have done a limited amount of editing. Messages having to do with separate topics were sometimes split into different files and sometimes extraneous information was removed. For instance, the message IDs were removed to save space and remove clutter. The comments made in these messages are not necessarily my viewpoints. I make no claims as to the accuracy of the information given by the individual authors. Please respect the time and efforts of those who have written these messages. The copyright status of these messages is unclear at this time. If information is published from these messages, please give credit to the originator(s). Thank you, Mark S. Harris AKA: THLord Stefan li Rous Stefan at florilegium.org ************************************************************************ Military Engines weapons which are convenient to have in naval warfare or in fighting on horseback, I will now ask you to say something about those which you think are most effective in besieging or defending castles. or on horseback can also be used in attacking and defending castles; but there are many other kinds. If one is to attack a castle with the weapons which I have enumerated, he will also have need of trebuckets: a few powerful ones with which to throw large rocks against stone walls to determine whether they are able to resist such violent blows, and weaker trebuckets for throwing missiles over the walls to demolish the houses within the castle. But if one is unable to break down or shatter a stone wall with trebuckets, he will have to try another engine, namely the iron-headed ram, for very few stone walls can withstand its attack. If this engine fails to batter down or shake the wall, it may be advisable to set the cat t to work. A tower raised on wheels ~ is useful in besieging castles, if it is constructed so that it rises above the wall which is to be stormed, even though the difference in height be only seven ells; but the higher it is, the more effective it will be in attacking another tower. Scaling ladders on wheels which may be moved backward and forward are also useful for this purpose, if they are boarded up underneath and have good ropes on both sides. And we may say briefly about this craft, that in besieging castles use will be found for all sorts of military engines. But Whoever wishes to join in this must be sure that he knows precisely even to the very hour when he shall have need for each device. Speculum Regale FROM: Simon the Strange SUBJECT: War Engines * Original: AREA.... MENSA * Original: FROM.... Bruce Wilson * Original: TO...... Dave Aronson
Journal that might be of interest to you and other SCA types: "A Scud It's Not, But the Trebuchet Hurls a Mean Piano" "Giant Medieval War Machine Is Wowing British Farmers And Scaring the Sheep" It seems some guy in England's managed to build a full-size (some 4 stories tall) working trebuchet and uses it to hurl grand pianos, small cars, and animal carcasses across the British countryside. Some British parachutists want to try it, but the acceleration is 0 to 90 mph in 1.5 seconds and produces centrifugal force of 20 Gs, which may be enough to burst human blood vessels. One of his incentives to build the thing was a "nutter cousin" in Northumberland who made a small trebuchet he used to hurl porcelain toilets that'd been soaked in gasoline and set afire. The article said that a local paper had headlined the story "Those Magnificent Men and Their Flaming Latrines." :-) ------------ * Origin: Aronson Consulting: TIDMADT 703-370-7054, voice x6508 (1:109/120) From: JRECHTSCHAFF at hamp.hampshire.EDU Date: 13 Nov 91 22:48:00 GMT Organization: The Internet
energy of a weight is released across a fulcrum (pivit point) to import kinetic energy to a projectile lodged at the far end of the lever. It follows that the greater the weight the less the friction, the lower the lever, the greater the mechanical advantage. The lighter more streamlined the projectile, the greater the thrown distance. The weight must fall through an arc to translate potential to kinetic energy. It's vertical acceleration (ignoring friction) wil be 9.8m/sec. squared. Now it will take a while for the weight to reach it's terminal velocity. Aha! You say blinded by a brilliant flash of the inuitively obvious. To get maximum acceleration my trebuchet counter-weight must fall "x" feet which means that this sucker has got to be tall. Tall equals big. How big? Try 120-150'. (See The Wall St. Journal Tuesday 31, July for an excellent article on a piano throwing modern trebuchet.) Now the overall height can be reduced by digging a pit between the uprights, but physics is still physics and you still need clearence for the weight so about 120' is it. Needless to say the greater the mass (the more accelerated the counter-weight) the more convinient - try depleted urainium. Seriously, the most readily available wieght is lead. Don't start messing around with old batteries - nasty stuff can happen to you and mother earth. A ton or two works well. The longer the lever arm the better. Now we're into materials. I happen to have an 80' ash pole but I like it in it's present form - as a tree. Old growth spruce is hard to find. You're best off laminating (laminating is period) up a pole from close grain spruce. Consult a wooden boat maker. If you are building a machine you now have two uprights (telephone poles are OK) about 6 to 8 feet apart, (obviously this isn't very portable), a very long lever pivoting on trunions across the top of the uprights and a counter weight fastened (hinged is best) to the short end of the lever. You now put a cup on the throwing end of the lever sufficient to hold a dead horse or a prisoner-of-war of choice. (See projectile below) You collect a bunch of serfs, haul the long end down with a rope, load, and have everyone let go. (In addition to a dozen rope burned palms, you let the end of the rope loop around your ankle and neatly amputate it. See trigger mechanisms) Assuming you have a pivoted or off-center counter- weight the lever rotates from about 180 degrees (pointed down) up through 0 degrees (pointed up) over to 270 degrees (where the projectile falls onto the ground) on down to the ground where it shatters while pegging the idiots standing there (remember the trigger crew?) or rebounds and jumps on its trunions or if your lucky, pendulums for a while. Obviously you need to stop the arm at some point. The theretical ballistically optimum turning point is 45 degrees. In practice however, this does not allow for sufficient fall of the counterweight, for friction etc. A practicle point is at about 30 degrees. The stop must be strudy well padded and well braced lest the lever frame shatter. This gives rise to an old medieval saying, "It is easy to build something that fires once building one that fires twice is something else." If the frame is built on skids the azimuth can be changed, if it is (was) more usual it is anchored to the ground, the azimuth is fixed. Range can be altered by changing the release (trigger) point or by building up the stop padding. (Throw a few more sheep skins on the stop.) Range can be increased by a third by use of a sling. The sling is one-half the length of the lever and rides with it's projectile, in a trough under the machine. There should be no slack. One end of the sling is fastened to the lever, the other loops over a horn at the end of the lever. (opps that should be that the sling is fastened to one end of the lever, the other loops over a horn at the end of the lever). Note that the release point is now changed by 1/2 the angle between the fastining point and the horn. The simplest trigger (and its shortcomings not to mention its tendency to foul the frame and sling) has been mentioned. A second form of trigger is a wedged in bar across the lever. The wedge is knocked out with a sledge hammer. However, one can be seriously killed by flying crossbars the size of railroad ties. Another trigger consists of a hook and eye released when a lanyard is yanked by a whipped up group of draft animals (not squirrels.) Payne-Salwery and others have illustrated some very nice trigger mechanisms that could be made by any competent smith. As with most medieval siege engines, tecbuchets were transported, knocked down and erected on site. Philippe Contamine writes in Guerre dans le Moyens Ages amusingly of an English king who spent months transporting and erecting a monster trebuchet to besiege a castle in Scotland. When the enemy saw that itwas ready they marched out and tried to surrender. The king, understandably piqued, refused, sent them back in, fired demolished half the castle and its garrison and then honor being served accepted their surrender. It is possible to build a trebuchet but not really worth the bother when you can build a ballista or catapult equally portable, wit hvastly better performance. I have a ballista with a 1000 # prod that I can carry by myself. It will shoot a 2' 3/8" rebar bolt through a car door. Reference projectiles. I propose an SCA standard, the humble common brick. it's cheap, readily available and regular in siza and shape. It generally conforms to the size of a medieval brick although it is significantly heavier. It is self-replenishing - as you shoot down the wall, you get more ammo! -Pierre D'Ussf, Artificer aka Peter Maleady (413)549-0786 From: ddfr at quads.uchicago.edu (david director friedman) Date: 14 Nov 91 05:23:41 GMT Organization: University of Chicago Computing Organizations "It's vertical acceleration (ignoring friction) wil be 9.8m/sec. squared. Now it will take a while for the weight to reach it's terminal velocity." (Lord Pierre D'Ussf, discussing the physics of a trebuchet) The figure you give for acceleration would be appropriate for a mass falling free by itself. The counterweight of the trebuchet, however, is accelerating the throwing arm and the projectile as well--and their weight is pushing in the other direction, since they are on the other side of the pivot. Furthermore, the relation between vertical acceleration of the weight and angular acceleration of the arm etc. changes with the angle. When the arm reaches vertical, for example, a small rotation produces no vertical displacement, since at that point the velocity of the counterweight is horizontal.
terms of rotational dynamics. Angular acceleration is torque divided by moment of inertia. The torque is ((mass of the counterweight times its distance from the pivot) minus (mass of the rest of the system (the stuff on the other side of the pivot) times the distance of its center of mass from the pivot)) times sin of the angle of the arm from vertical.
velocity when air resistance exactly balances torque. I doubt that is likely to happen at any plausible speed.
counter-weight) the more convinient- try depleted urainium." (Lord Pierre)
depend on its mass, as Galileo pointed out some years back. Increasing the ratio of the mass of the counterweight to the mass of the rest of the system will increase acceleration (see my verbal equation above)--but that would not be true if your original statement (quoted before this one) were correct. I think you may be confusing weight with density. You can get plenty of weight with a box full of dirt and stones, which I think is what they mostly used.
practice however, this does not allow for sufficient fall of the counterweight, for friction etc. A practicle point is at about 30 degrees." (Lord Pierre) Forty-five degrees is the optimum angle if velocity does not depend on the angle. With a trebuchet velocity is increasing as the counterweight falls. The effect can be exactly calculated--that part is not a matter of "practical points." Patri, back when he was teaching physics classes, used to give it as a problem to his students. Friction is more complicated. With a sling, the velocity of the projectile when it is released is no longer at right angles to the arm, as it is with a rigid throwing arm. That means that it should be possible to combine the optimal angle for the projectile's velocity (45 degrees from vertical) with maximum velocity (throwing arm upright, counterweight all the way down), giving a longer range than would be possible for the same trebuchet without a sling.
when you can build a ballista or catapult equally portable, wit hvastly better performance." ((Lord Pierre)
strong cord--and there are, I believe, problems as you try to scale the beast up. All a trebuchet needs is wood, a little metal for release mechanism and such, and dirt (what they filled the counterweight with).
physics from Aristotle) From: cctimar at athena.cas.vanderbilt.edu (Charles) Date: 18 Nov 91 05:51:21 GMT Organization: Vanderbilt University student of numerology
>
> "The theretical ballistically optimum turning point is 45 degrees. In > practice however, this does not allow for sufficient fall of the > counterweight, for friction etc. A practicle point is at about 30 > degrees." (Lord Pierre) > > Forty-five degrees is the optimum angle if velocity does not depend > on the angle. With a trebuchet velocity is increasing as the > counterweight falls. The effect can be exactly calculated--that part > is not a matter of "practical points." Patri, back when he was > teaching physics classes, used to give it as a problem to his > students. Friction is more complicated.
angle is the angle at which you are hitting your target, which is not necessarily the angle that throws the projectile the farthest. Of course, if you are overshooting, you will probably correct by removing a stone from the counterweight, rather than trying to adjust the stop.
fixed firing velocity can usually be achieved by firing the projectile at 35-40 degrees above vertical. The best way to compute the actual angle is to do a computer simulation. The second best is just trial and error - I would start by subtracting 5 degrees from the angle that you compute the way Cariadoc suggests. Of course, there is also some friction involved in the arm spinning on its axis. I don't know how large an effect this will have. -- -- Charles, student, in Glaedenfeld, Meridies From: PAMCCOY at GALLUA.BITNET ("Pat McCoy a.k.a. Bones") Date: 26 Nov 91 22:49:00 GMT Organization: The Internet
who responded to our inquiries concerning siege machines that chunk punkins, pianos and cars. :-)
asking questions (through a member on the Rialto) about trebuchets. I have taken great pleasure in the responses Pat McCoy had forwarded me from the Rialto and appreciate the resource you have been to me and my students.
the following problem: "Design a machine which can throw an 8-10 pound pumpkin as far as possible, using the limited materials available." The students took sevel different approaches to the problem, from creating original designs to researching ancient siege machines. The trebuchet idea cropped up from a Wall Street Journal article on an Englishman's current project, (cited here incidentally). However, there was not enough information from that article to build a machine. The tips and suggestions (including excellent references) provided from several members on the Rialto set us off in a better direction. One team of students, (an all-girls team, by the way), constructed a small trebuchet, a simple counter lever device, (16-foot throwing arm, 225 lb. counterweight) and proceeded to tromp the other high school contenders. Our best throw was only about 37 yard with a 6-pound pumpkin, but the sight of that machine working was beautiful. The sling just sailed magnificently up and over, releasing the pumpkin at least a yard above the throwing arm. We adjusted parameters, (counterweight mass, length of sling lines, sling attachment, weight of the pumpkin, etc.) and collected data that is going to provide us with problems for much of the rest of the year. We have videos which will be analyzed in slow motion for other data.
centrifugal design) were carted to Delaware on November 2nd to participate in an annual pumpkin throw with adult teams from the local area. We were the only high school group to throw. Best throw of the day was 702.6 feet, somewhat short of the world record set last year at 776 feet. These throws were accomplished by an adult team with a centrifugal machine consisting of a 30-foot arm driven with a belt from the rear axle of a pick-up truck. (I apologize for this non-period stuff if it is not of interest. I didn't know how much to share about this rather extensive project, after getting such kind responses from the many of you who shared your knowledge.) There seems to be a clamor from physics-student-wannabe's for a repeat performance next year. Now that we know a little more about what we are doing and have some references in hand, I hope to throw in the 'several hundred feet' range mentioned graciously in several Rialto postings.
commended you on your preservation of the Middle Ages. May the Age of Chivalry live on forever.
Science Department Model Secondary School for the Deaf at Gallaudet University, Washington, DC"
in this endeavor! Padraigin nic'Aodha - Barony of Storvik - Kingdom of Atlantia Pat McCoy - Washington, DC Trebuchet blues 15 May 92 From: rday at magnus.acs.ohio-state.edu (Robert E Day) Newsgroups: rec.org.sca Organization: The Ohio State University
ites:
>Greetings unto all gentles who may read this! > >I have nearly finished a "quickie" prototype of a trebuchet. The arm >is merely 4 ft. in length. However, I have now come to that difficult >position of attaching a sling. My first attempts (with a hacked up >badmitton net) were, um, less than successful. I tied the ends of the >"sling" in such a manner that it would have a cupping effect... however >when the sling is released from its hook the projectile merely rolls >up the length of the sling and gets caught in the end. I've tried >remedying this in several ways with either no change or even worse side- >effects. > >Can anyone, who has made one, enlighten me with a description? I would >me _most_ grateful! > I have a friend who made one with an arm about 8 feet long. He used a small piece of leather(about 6" square) attached to rope as the sling. One end of the rope was attached to the arm only by a ring which hung on a hook and the other was securely attached to the arm. He used it to throw 8" warrer ballons. --
If the price that I must pay to obtain my * Robert E. Day/Syr Otto von * freedom, is to acknowledge that the Gov- * Schwartzkatz, Shire Mugmort * ernmet was granted the power to infringe * Barony Middle Marches, * on them, then I am not free. Paul Anderson* Middle Kingdom * 15 May 92 From: amlsmith at morgan.ucs.mun.ca (Andrew Smith 8848111) Newsgroups: rec.org.sca Organization: Memorial University of Newfoundland Greetings unto the Rialto from Sebastien. Located in far off Ar n-Eilean-ne, (Nfld., Canada). I have reason to believe that I am the last siege engineer before hitting Drachenwald. I too, am searching for information. The choice of the Trebuchet is a good one, less stesses are involved and therefore, safer. Directory: files -> COMBAT files -> Socials 11: Provincial Exam Review Preparation Essay Component files -> 9. 5 Political Powers and Achievements Tom Burns- beacon High School files -> Indiana Academic Standards Resource Guide World History and Civilization Standards Approved March 2014 files -> On the Vanity of Earthly Greatness” “Ozymandious” Arthur Guiterman (1871-1943;1936) Author files -> Understanding Diversity What is Diversity? files -> Sscg: 16 Unit 7: Judicial Branch COMBAT -> Women and the Art of Battle in the Late Middle Ages COMBAT -> Women-Warriors-art – 7/12/09 COMBAT -> Note: See also the files: rattan-msg, tournaments-msg, melee-tactics-art, armor-msg, p-armor-msg, swords-msg, axes-msg, Shield-Balanc-art, w-t-shields-art, Sword-Fighting-art, wood-bending-msg, wood-msg COMBAT -> Note: See also the files: tournaments-art, tournaments-msg, marshalling-msg, b-battles-art, jousting-msg Download 344.45 Kb. Share with your friends:
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