Interesting, but I think that the (current) last poster on the thread probably got it right by asking where the romans go the "air friction" knowledge from. A slung stone only has the potential to heat by a fraction of the energy put into it, and if you take the kinetic energy in minus out you don't have much left over! Look at how much "work" it take to start a fire using wood friction.

The ballistics of the sling - Thom Richardson: 30 m/s X 100g gives 45 Joules. The specific heat of lead is low at 0.16 J/g°C so you need .16 Joules to heat 1 g of lead by only 1 degree C. Our lead needs 16 joules per degree, so the total possible (not even close to possible of course) heating is only ~3 degrees (bringing the lead to a complete stop, not air heating, no convective cooling).

It might be interesting to mention that the examples usually given as "proof" of air friction heating (shuttle, meteors) are really poor. The heating in a shuttle reentry is not skin friction, but compression heating in the shockwaves. The heat leaks across into the boundary layer, where turbulence transfers it to the skin. The shuttle comes in at more than 8 km per second, and reaches speeds of +Mach 10. Most of the engineering that goes into reentry vehicle (or high speed aircraft) design is put into shaping of the leading edges/airframe to keep the cone away from the structure.

Another interesting thing is that due to the extremely low specific heat of lead, you can't really do much damage with it. You can pour hot lead into you hand, for instance (try that with water). If you drop the glans from above heated to 300 degrees (just below melting) into a coffee cup of water, you raise the temperature of the water by only ~5 degrees...

Boiling oil is much more effective.

Matthias (feel free to tear apart my math)

The RAT (Roman Army Talk) forum has moved to a different server, and seems to use different software.  The link Johnny gave (four years ago!) is broken.

I did a bit of searching and I may have found the topic;

here is a link to it

.  It is the only topic that was returned from a search for anything containing all the keywords "hot", "lead" and "glandes".

In case anyone is interested, one of our members performed an

informal test in 2005

, using a lead glans against a concrete block; he reported that the lead was badly deformed by impact, and noticeably warm to the touch ("still hot when I picked it up" were his exact words).

[quote]You can pour hot lead into you hand[/quote]

Can I suggest that perhaps you don't :-)
just to be on the safe side.

Having smacked lead glandes through plywood and into metal last year I can categorically state that it is not noticeably warmer afterwards, not even the edges of the deformed part.

However I wasn't looking for any increase in temperature, it's possible that those who were just thought there was an increase because they wanted one.

Not sure if anyone's mentioned it yet but if lead was heated by passage through the air then bullets would all melt in flight. They get hot sure - but then they are pushed through a  hot barrel by expanding and extremely hot gasses. So probably more down to that than air friction :-)

Gronk wrote on Apr 29^th, 2008 at 4:47pm:

G-D moonshine is so illeagal

Gronk wrote on Apr 29^th, 2008 at 10:27pm:

                       "GEORGIA MOON"........Available in most liquor stores in America." Pocheen" in Ireland.

pocheen is pretty much made from whatever comes to hand but traditionally it's potatoes. and the reason home distilled liquor makes you go blind is because it's got a high percentage of methanol in it - which is seriously poisonous. Stick to the commercial stuff :-)

I recently did some velocity tests with lead pistol bullets that involved firing .44 special bullets over a chronograph into a backstop made of stacks of old phone books. The bullets clocked right at 800 feet per second (several times faster than a human can sling) I recovered some of them within 30 seconds of firing. They were really bent up and mushroom shaped but I don't recall any of them being warm to the touch. Lead is a very dense material and holds heat a long time. It takes a good while for cast bullets fresh from the mould to cool off enough to be handled, and I have cast thousands of them. I am positive that this is a myth.