Oracle,
funny, i was just reading an article on that very thing last night in an old (1976) modeling magazine i got in a lot on eBay!
i will see what specifics it has.
if you want you can email me at the address connected below,
and i will arrange to to get the info to you.
it is not the 'be all, end all' on the topic,
but there should be some useful data.
ed.