Leonardo da Vinci

Inventions

 
 

Leonardo made two drawings of catapults in the codex Atlanticus (above), dated somewhere in the 1480’s. While gun powder had been invented well before this, he seemed to understand that it wasn’t always reliable and that catapults still had a place in warfare. The da Vinci catapult took and interesting turn (as it were), since none were made like this before that have been documented. Da Vinci was often pitching to kings and local lords (to whom he was employed), new ideas to protect their castles and improve their effectiveness in battle (note the tank and other nasty weapons he has drawn).

He made two designs, a single arm and a double arm. It looks like the tensioning arms would have used a laminated wood of some kind, but the tension on them would have been huge.


On the single arm there was a long pole (on the right of the above drawing) that inserted into the drum so the swing arm could be put into firing position. It used a ratchet system where as the arm was pushed into position, a ratchet would prevent it from firing. Once in position, the release mechanism was pulled (on the left of the bottom drawing). We used that type of release mechanism in our catapult model, but not the long arm to push the swing arm into place, since there is little pressure on a model and the swing arm can be easily pulled into position.

The (top) double arm catapult used a different winding mechanism, and Leonardo gave a nice illustration of it in the top right of his drawing. It essentially is a worm screw that would slowly wind a large wheel (improving leverage) that would move the swing arm into position. It would be engaged in the wheel, wound, then when in position, a release mechanism would be engaged to hold the tension.

The worm ear would be lowered so it was not engaged, and the release mechanism would be tripped and off goes the projectile! The tension must have been enormous, and  it has never been discovered if either of these models were ever made or used in battle.

Catapult 

Another iconic part of Leonardo’s legacy, the ornithopter he designed in about 1505 is a tribute to his desire to see humans fly under their own power as birds do. While this design was unlikely tested during his time, and he made few detailed drawings, people have created a wide variety of designs based on his drawings. Of course Pathfinders weighed in on this design and our ornithopter team added gears that he drew to make it work. It is not clear, (since we don’t have most of Leonardo’s notes and drawings) if he understood the concept of lift on an airfoil. He did understand that the teardrop shape is what allowed fish to swim quickly, as some drawings of this do exist. Leonardo did numerous drawings of mechanical wings of every type (as noted here), and he worked hard to replicate the flapping action of a birds wing mechanically. He did seem a little obsessed with flying, and his drawings of dissected wings showing the tendons going through the joints are replicated in the joints of his wings.

As we know, the weight of the machine and flyer would have been so great upon the wings  (that gravity thing) it would have been impossible for a person to push against the weight of the air pushing upward - it would have been very hard to push the wings down. He changed the design somewhat to account for this, by using the leverage advantage in a geared - bicycle like system to improve the strength of the pilot, but the wings would have moved far too slowly for the ornithopter to stay aloft. While one of his gliders have been recreated  (and it worked!) this one - at least one similar to these designs have not been recreated.

That being said, recently the Snowbird Human-Powered Ornithopter was designed and constructed by a team of students from the University of Toronto. Have a look here

Ornithopter

While it is clear this helicopter-style flying machine didn’t work, it has sparked the imagination of many generations as one of his iconic inventions.

It really didn’t work like a helicopter, as his premise was that air, like water, was a fluid, and that one could drill into it since it had mass. If air was as thick as water then it might have worked! Not sure why he didn’t try this underwater. Something about breathing underwater I guess (but he did have drawings for a submersible breathing apparatus!)

Helicopters actually work on the principle of lift (the flow of air over an airfoil shape giving the lift) , which this clearly did not. Probably the best video of how it might look and work is shown in this excellent video located here. Pretty quirky (and somewhat long) actually, but fun!

Of course the aerial screw wouldn’t work since as soon as it lifted off the ground (which was unlikely anyway since it would have weighed way too much), the people turning it would have nothing to push against, and so they would all be spinning in the same direction, so the driving force would stop. But it is fun to dream! There is a great essay written by Dylan Connelly that discusses this machine.His article is a download, so if you do an internet search it will download (there is no web site) A Study of Leonardo da Vinci’s Inventions: The Aerial Screw.

Our model (left) now available, spins like we think Leonardo wanted it to, and uses one of his worm gear designs to accelerate the canopy to a pretty fast speed. We made a 2 to 1 gear, so one turn of the handle will make the canopy spin two times - yikes! Get out your Renaissance Lego people and put them to work! You can get them online at the Met museum, or Hobby Lobby in the USA, among other places.

Aerial screw - helicopter

Our model combines the simple release mechanism of the single arm, above, with the extra power of the double tensioning bars. It is not exactly true to Leonardo's drawings, but we’re OK with that - for the sake of a quicker firing time.

We made an ornithopter model. It isn’t exactly as Leonardo described it, but to make it work we had to take some liberties! (Leonardo would be OK with it we think).

Leonardo da Vinci made many sketches of wings as he tried to work out the mechanics of an ornithopter

Leonardo Bridges

           Leonardo da Vinci lived in warring times and he realized that one of the ways to stay safe and make some money was to have local powerful Dukes and patrons support him in his endeavours.  At the time, Ludovico Sforza (Il Moro) was Duke of Milan and was a patron of many artists and architects, including da Vinci. During his time in Milan (and later on) he designed a number of interesting bridges.  Having a good engineer to design castles, and weapons to defend (and keep invaders  at bay!) was very useful for these Dukes and Kings, and Leonardo rose to the occasion and sketched many weapons - and means of defence for his patrons.

Leonardo made a number of cool bridge designs.  As part of a civil engineering project for Sultan Bayezid II in 1502, he made a drawing of a single-span 240-meter (790 ft) bridge (below - left) designed  to span the Golden Horn  Inlet (the name of the water body it was to cross). While never built,(the technology to make it didn’t appear for another 300 years) its elegant lines have inspired a beautiful footbridge in Norway based on this design!

Leonardo designed this bridge for the Golden Horn Inlet in what is now Istanbul.

It was actually built in 2001 in Norway as a foot bridge!

       The bridge we made, sketched sometime between 1485 and 1490, was designed to be built rapidly with  local trees, that could be easily slid into place, lashed together, and then crossed quickly, making troop movement over rivers speedy,  creating a surprise factor that was critical to success in battles. Leonardo applied the laws of statics, which he had developed during his architectural research.  In his journals he wrote laws about friction, one of which stated that if the load on an object is doubled, its friction also doubles. Interestingly, when weight is applied down, it gets tighter and stronger, yet when lifted it falls apart (get one and try it!).


Leonardo also designed an early swing bridge, (above) as well as a two-decked bridge (sorry no drawings here - we’ll try to get one), for movement in  two directions at once - the first commuter bridge!

Since early times engineers have designed many different types of bridges, each specific to the area it was needed. When there was river traffic, they would have to be high, or lift or swing, and when long they have to be cable stayed.

The “Emergency” Bridge was drawn on a page with a lot of different illustrations. On the one page he drew two styles of bridges, some closeups of connecting methods, a crossbow (or two) and at the top - a sketch of a church! It is unlikely he did them all at the same time, but it does show his eclectic mind! Our bridge kit has grooves to help hold it together, but his design showed lashings  (rope) to hold it in place.

An elegant design, this swing bridge was attached on one side and anchored with a weight filled base. You can see the rope on a pulley at the bottom which would have been pulled to open the bridge. It would have rotated around the vertical pole on the right.

This illustration shows how bridges could have been made, and how it would have been attached to the shore. Note the pulley on the post to level the platform. Leonardo made a closeup drawing of this simple machine. He thought of everything ! (note the closeup of how it would attach to the ground - bottom right in the drawing above.

This is his transportable suspension bridge. Not sure exactly how it works, but it might have been able to be expanded to stretch out to the width of the river. Very cool!

Emergency  - (and no so emergency) Bridges

Since early times engineers have designed many different types of bridges, each specific to the area it was needed. When there was river traffic, they would have to be high, or lift or swing, and when long they have to be cable stayed. Leonardo seemed to have considered many types of bridges and while he is famous for other things, there is little question he should also be famous for his bridge designs!

There are lots of great bridge websites on the internet, check out the PBS educational site: Building BIG, lots of great interactive activities!

Leonardo’s trebuchet design was quite different from all that went before him as it had a single pole that the swing arm was attached to it. Of interest in this design is that if you look carefully it appears that the mast that the swing arm was attached to seems to be buried into the ground, and in fact if there was an appropriate sized tree where the trebuchet was needed the swing arm and counterbalance could be mounted on top - no need to build a superstructure!

However the drawing isn’t entirely clear and it looks like the counterweight box is one solid box, so if it was made like that the box would hit the post as it swung down through the bottom, which would mean it would not work.


It is possible that this was merely a sketch to show that he knew how to make machines of this nature, and that the people he would show it too didn’t care too much about the details, but to make this design work there would have to be two boxes - one on either side of the mast.


As previously noted, Leonardo’s siege engine designs, and even many of his bridge designs were made as part of his résumé, when he was looking to get the job of military engineer with a Lord or Duke. In fact it has been suggested that the underwater breathing apparatus he designed was to get a job with the Duke of Venice, to help him defend against attack from the sea (his idea was to wear the underwater outfit, walk along the floor of the harbour, drill holes in the hull of the invading armies ships so they sink in the harbour and cannot attack). He didn’t get that job...

Typical of Leonardo’s designs however was a nice little drawing to show how the machine would be recoiled - the ratchet on the bottom left.

But again if you look carefully the ropes don’t look like they are set up correctly. The release rope - which is the horizontal line from the base of the mast would have a release mechanism of some kind (he did draw different designs in other places), but the winding rope wound its way to the top of the mast where it would pull straight down the swing arm, which would not work to recoil the arm for reloading, it must be on an angle from partway up the mast (as we have done).

It is likely Leonardo knew that the people he was showing this too would not understand the specifics of the machine, so it is possible he just drew ropes on to show that there would be a way to reload the trebuchet. If you look at our model, we moved the connection for that down the mast so it pulls the swing arm down efficiently.



Trebuchet

Our model moves the counterweight  box to the side, rather than making two boxes. However the basic premise is the same, a much easier to make and use trebuchet than ones from the middle ages (but it has to be stuck in the ground!)

This sketch (above)shows another trebuchet design possibly by Leonardo, but the drawing technique is not exactly the same style as many of his other drawings, so not everyone is convinced it is his design.