Any good source about Springald/Espringals?

Hi all,

It seems those torsion springalds are rather poorly investigated if not almost forgotten weapons. Is there any good source about their properties and historical background?

Hero,

Have you got this book already?  http://www.amazon.com/Springalds-Crossbows-Espringales-Arbaletes-Armouries/dp/0948092319

I was not very impressed with it, but it's the only book of it's sort.

Mac

There's this:  Springalds and Great Crossbows, by Jean Liebel.  There are some interesting illustrations, but the guy's got some pretty screwy ideas.  Guy Wilson, the  Master of the Tower Armouries wrote an 'interesting' forward that rather damns with faint praise... he doesn't outright say Liebel is full of malarky, but he comes pretty close.  Still it's about the only available work on the subject, and the period illustrations are informative.  It looks like Liebel did all his reconstruction work with small scale models and came up with some peculiar solutions to non-problems.  As the Chinese say: "may you be born in interesting times." or perhaps more appropriately, "may you be provided with 'interesting' sources."
Geezer

I have no chance of getting the book where I live. Also, there is no e-book version of it as far as I know. It is not surprising for me to hear dissatisfaction of such a 86 page "book" but unfortunately there is no other work available in this area.

Overall, torsion weapons of medieval era is rather neglected subject of medieval military engineering but I was hopeful about sprigalds which are kind a better documented, relatively late weapons but it seems my assumption failed.

Back @ 1900, there were a number of people experimenting with medieval siege engines.  There were a couple of Germans named Diehls and Schram, and of course Payne-Gallwey included a fair amount of stuff on catapults and balistas in his "The Crossbow, Medieval and Modern" which is still in print as "The Book of the Crossbow." Liebel's book is useful and informative, despite its 68 pages, with LOTS of reproductions of period illustrations, but there are some points where I just scratch my head... Why the heck did he do  it THAT way???? He makes certain elements absolutely the hardest impossible way.
If you want more authoritative modern sources on, look for a scholar named Marsden (Green and Roman Artillery) He published quite an authoritative work on the subject @ 1968... from one of the big English universities... either Oxford or Cambridge University press.  Further research online should turn up many more scholars and engineers working on siege engines in particular, though most seem more interested in catapulta and balista.  There are even some trebuchet nuts out there.  Keep looking... you'll find what you need.  Geezer

Geezer again:  Here's the source.  EW Marsden, "Greek and Roman Artillery" Oxford, Clarendon Press, 1969.  Readily available at a number of online shops.

Thank you so much Master Geezer. Even though the sources mentioned, Marsden, Diehls and Schram could be useful in case of understanding torsion principles but all about ancient artillery which is not what I am looking for. In the book of crossbow by Payne-Gallwey again Roman onager, ballistae also investigated. Additionally, Payne-Gallwey adds some information about a late rare tension springald, coining it with another name "spring engine" yet interestingly his books lack anything about torsion springalds of high medieval era.

The "spring engine";



My point was actually learn more about torsion springalds but it seem there is not much document about it. However, I managed to find a Russian summary of Liebel's book which is quite understandable with Google Translate even though some flaws.

http://www.xlegio.ru/throwing-machines/middle-ages/torsion-springald/

I am glad to know you have found a translation of Jean Liebel's Springald book, even with its peculiarities/flaws.  Payne Gallwey is readily available, but his books suffer from their age.  The scholarship is good.... for 1907.  Marsden is much more modern and scientific.  From my limited exposure to other catapult lovers, I gather Marsden's book is more or less the standard starting-point for contemporary catapult investigators, so it's worthwhile looking at his work, even if he's not really talking about the engines you want to consider.  To me the most interesting thing about Liebel's springald lies in the fact that it's an inswinger (arms swing inward) rather than the more common out-swinging Roman style catapulta. Many modern catapult fans believe the in-swining design can be more efficient. 
I agree an inswinger can be more efficient, but the frame is necessarily large and unwieldy.  It might be useful in a fortified place, but I can't imagine an army using such things in the field.  Good luck on your research!  Geezer

Master Geezer, I agree with your evaluation of sources and you are absolutely right about how Marsden's work is first stone to step into all confusing yet entertaining universe of torsion catapults.

About in-swinging arms, Liebel is actually lucky since there are few pictural evidences supporting the evidence springalds with in-swinging arms. Also, Springalds were better documented than ancient siege engines.

Below image is by Roberto Valturino in 1466.



While talking about in-swinging ancient artillery scholars conflict in many aspects. It is true that in-swinger design could harness more power from skeins but this could be  mere a modern design without any evidence. Hopefully, some archeological and literal evidences are available. Apparently, there were some in-swinger machines used by Romans but at this point another question arises; Was this knowledge passed to Medieval time or Was in-swinging design re-invented by medieval siege engineers?

As I said earlier, torsion weaponry in medieval are is rather problematic subject so it is true for this particular arrow shooting engine.

Here a good article about in-swinging ancient artillery.

http://www.google.com.tr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CDAQFjAB&url=http%3A%2F%2Fgladius.revistas.csic.es%2Findex.php%2Fgladius%2Farticle%2FviewFile%2F47%2F48%3A3cv416cf&ei=hTJpU6jSJaqCyAOSioGgAQ&usg=AFQjCNFj3YyU5N1LOIRybe0MH6fjqDrf1g&sig2=qGIt4C53QORYtEd3E7kf-g&bvm=bv.66111022,d.bGQ

A thing that strikes me about Da Vinci's machine is how he has shown the frame members flexing under the tension of the skeins.   I wonder if this is a "bug" or a "feature".

Mac

I would say it's definitely a feature.... one would want to construct the frame of the right materials so you could use the flexion of the side timbers in storage of energy.  The other pics don't seem to show this, but you know darn well it's gonna happen.  Leonardo was smart enough to use this to improve performance. 
I still think the whole frame is a bit unwieldy, and think simpler, more robust out-swingers would make better machines for siege work.  But inside an enclosed space, this one might work pretty well.  Geezer

Ya know:  looking closer at some of these springald drawings, I don't see any means of tuning the torsion-skeins for best balance.  Both Payne-Gallwey and Marsden pay a lot of attention to means used to adjust tension in each sinew-bundle... as I recall Marsden suggests Roman machines were adjustable... each bundle, to with 1/2 of 1 percent.  That would give them a very accurate machine, suitable for repeated shots to the same section of wall over a long night (or day) of shooting.  Of course it's possible springalds, being lighter machines, were more intended for counter-battery fire, or picking off enemy officers during a siege, so careful balance of power on both sides might not matter as much... Geezer.

@ Master Mac, Da Vinci uses this flexible frame for torsion springs in several occasions. Yet, today, experts assert that rigidity of frame is obligatory to harness full power torsion bundle which is made by sinew in case of ancient artillery. So bending frame could be disadvantageous according to some scholars but there is no investigation or experimentation about if as far as I know.  

Also, there are some additional problematic points in the drawing. A close look to above drawing reveal that there are four arms instead of one. In my opinion this feature could be used while cocking the machine. By knocking a cord consecutively to respective arms, operator could draw draw machine further till it regarded as sufficient. Another point, there is no torsion bundle at all. Two thick ropes round around frame and hold frame and a special piece that hold four arms. Thus in my humble opinion machine is designed to harness power of tension of frame rather than torsion of a skein bundle. Below image is another design about flexible frame.



@Master Geezer, Your observation about lack of adjustment mechanism is right since those times, ancient time's sophisticated mechanisms were either forgotten or the available skill in medieval era were not sufficient to produce such complicated parts. Thus, this robust machines become popular since they were easy to build and maintain. Available information about sprigalds shows that these were deployed mostly for covering important areas around castle walls such as gatehouses. Terrifying power of this machines frightens the approaching soldiers since neither thick armor nor even pavises could stand against missiles thrown by springalds. One account mentions about a bolt piercing several men in a row. A large mass of soldiers packed in front of gatehouse would not require much adjustments so siege engineers may not need specific adjustment apparatus.

Behind the link there are couple protos I made few years ago
http://perinnejousi.utbl.net/keskustelu/viewtopic.php?t=981



Fine tuning of flexible frame is done by tillering the horizontal beams like normal bows. The ropes just need to be measured carefully.
It also helps to have long skeins that can be tuned with adequate precision by half twists.
And of course length and thicness of the arms can be varied wihin limits.
Also adjustable wedges could be placed under the skeins , or between vertical beams and top frame.


Main advantage of flexible frame is cost and reliability. Expensive and sensitive sinew torsion bundles can be replaced with thin skeins of regular inflexible hemp rope.

Great work, Master Nerd Flintstone! :)I had already seen your amazing product of craftmanship while searching about springalds but never noticed it has flexible frame.

I am humbly reminding the fact that there is no torsion coil in Da Vinci's machines unlike your sprigald. Only a minimal length of rope of unknown material used to transfer the power caused by tensioned frame to throwing arms.  

Also, in medieval ages since animals are valuable assets, engineers preferred to use horse hair instead of much expensive and sensitive sinew cords. According to Liebel's book, pound of horse hair brought and sold to inventories of medieval lords for springalds.

How did you reach the conclusion of replacement of sinew with hemp? Is it mentioned in historical records of innovation of modern engineers? I am highly doubtful of performance of a coil with consist of two materials with different properties.

HeroSK wrote:
How did you reach the conclusion of replacement of sinew with hemp?

Just reasoning.
If the frame is storing energy, the skein is there just for transmission. So the cable should be inelastic like a bowstring. Hemp being a traditional bowstring material was a logical choice.


( and the hemp used here might be flax. It was sold to me as flax but it stinks like hemp. Strong fine natural fiber anyway )

I got confused with ordinary torsion weapons which use power of twisted skeins of horse hair or sinew. In case of  Da Vinci's tension powered springalds, I agree about hemp would be good transfer materiel of energy.  Apparently, there is no historical evidence supporting Da Vinci's springalds. Thus we can conclude that his design left on paper just like hundreds of his inventions yet his particular weapons need much more attention and investigation.