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Robert MacPherson
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Location: Jeffersonville USA
Joined: 27 Feb 2008

Posts: 141

PostPosted: Wed 15 May, 2013 9:19 am    Post subject:         Reply with quote

OK...

I have gone back and looked closely at Andre's reconstruction. It seems that we are closer to being on the same page than I thought at first, and my initial reaction was too hasty and too harsh.

Andre's reconstruction is consistent with my current understanding of these objects. I have looked carefully at the videos; freezing them to examine the mechanism. The mechanism only serves to secure the shield, and then release it on impact.

I was initially disappointed that the shield did not fly into the air, but I now believe that the balsa tipped lance is not supplying enough energy to make that happen. If it were struck with a solid lance, I imagine that it really would go up into the air. The mechanism is essentially well reconstructed, and working reasonable within the limits of the constraints imposed by the armor and the lance.

If you are out there, Andre, please accept my apologies.

Mac

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Nathan Robinson
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PostPosted: Wed 15 May, 2013 9:49 am    Post subject:         Reply with quote

Robert MacPherson wrote:
I am beginning to wonder if the mechanism is actually supposed to cast the shield and its parts into the air, or whether its function is only as a release, and the force of the impact is supposed to carry the shield up.

If we presume that the mechanism is only there to retain the shield until impact, and that the force of the lance is supposed to do the work of lofting the fragments over the jouster's head, the various wheels and rollers begin to make more sense.

The pics all seem to show that the shields are composed of two layers. The first is the foundation; which remains intact. The second is the covering; which is composed of "pie slices" of steel(?) that are secured under a central boss. I presume that the pie slices are held in such a way that a strong impact will dislodge them. In this sense they are not unlike the ablative brow reenforcing plates on the sallets.

As I see it...
-- any impact to the shield will cause the mechanism to release the shield.
-- a strong impact will carry the shield up over the jouster's head.
-- the stronger the impact, the higher the shield will go.
-- the stronger the impact, the more cover pieces will be dislodged.

.....Thus, better impacts produce more spectacle.

As a corollary, I presume that the images which show the shields in pieces high above the heads of stationary jousters represent an illustrative conflation of time and space, and are not meant to be taken literally.

Mac


I suspect you're on the right track here.

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Edward Rees




Location: Portland, OR
Joined: 02 Dec 2010

Posts: 29

PostPosted: Wed 15 May, 2013 8:23 pm    Post subject:         Reply with quote

Robert MacPherson wrote:

As I see it...
-- any impact to the shield will cause the mechanism to release the shield.
-- a strong impact will carry the shield up over the jouster's head.
-- the stronger the impact, the higher the shield will go.
-- the stronger the impact, the more cover pieces will be dislodged.

.....Thus, better impacts produce more spectacle.

Mac


Looking at the breastplates I think you are missing an action.

The mechanism at the bottom of the breastplate is connected by an arm to a hinge at the top. I suspect that striking the shield caused the arm the fling the shield into he air.

The church is close but the roads are icy; the tavern is far, I will walk carefully.
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Robert MacPherson
Industry Professional



Location: Jeffersonville USA
Joined: 27 Feb 2008

Posts: 141

PostPosted: Wed 15 May, 2013 9:36 pm    Post subject:         Reply with quote

Edward,

Do you mean the big forked arm that sits beneath the lower wheels?

Unless I miss my guess, that's the trigger. The wheels are able to travel a short distance in slots. If they are pressed in by the impact of the lance on the shield, they press on the ends of that bar, and that trips the mechanism.

Half way up that bar is a screw, I believe it is sensitivity adjustment.

Mac

Robert MacPherson
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Edward Rees




Location: Portland, OR
Joined: 02 Dec 2010

Posts: 29

PostPosted: Thu 16 May, 2013 11:25 pm    Post subject:         Reply with quote

Robert,

Just to make sure we are comparing apples to apples I'm primarily speaking about the first image in the post.

A few inches above the screw you mentioned is a hinge that allows the entire assembly to swing up. Centered between the brass wheels is an eye bolt with the top section cut out. I think that this and the two eye bolts at the top of the breastplate are the attachment points for the shield. I suspect that the shield was attached with wooden dowels designed to fail on impact at the top attachment points and something more durable at the bottom point. The bottom eye bolt with the cutout would act like a hook on a trebuchet and not release the shield until it a certian point. The wheels are there to reduce friction and help the shield fly off at the right point. The image quality isn't fantastic but I don't see any evidence of a catch holding the arm down and if I'm right about the wooden dowels then they could act as a trigger for any mechanism designed to pop the arm out.

The order of operations that I envision is
1. Lance strikes shield
2. Wooden dowels break releasing mechanism
3. Arm swings out
4. Shield reaches release point and flies into the air

On a good strike the rider's torso would thrown back violently causing that arm to swing out rapidly and impart a great deal of upward momentum to the shield.

-Edward

Edit - Just watched the video... I missed it the first time reading through this thread. Sigh, all that speculative reverse engineering gone to waste. Though I do believe that the physics behind how I pictured this functioning would work.

The church is close but the roads are icy; the tavern is far, I will walk carefully.
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