April 10, 2022 at 5:51 pm #10568
That Polhemus computer, do you know where I might obtain one? I’ve been hunting to no avail.
(I’m also desirous of a sextant with averager – the A12 is proving very finicky.)April 11, 2022 at 7:41 am #10569
This one has been sitting on eBay for quite a while. Appears to be unissued.
eBay also has quite a few aviation sextants. Some, like the A12 or AN5854 have eyeball averagers (you use your eyeball to average a number of pencil marks on a disk or pins on a carousel). I see 3 Kollsman sextants: an MA-1 (pendulous mirror), MA-2 (bubble), and a couple of periscopics. All 3 are with the clockwork averager. I cannot vouch for any of them – I’ve done various repairs to Kollsman sextants but some are beyond my abilities to fix.
If you see a listing by “mr.enfield” then look hard at getting it. He refurbishes aviation sextants and he will ship you a sextant in working order.April 11, 2022 at 2:31 pm #10570
I’d seen that one, but it appears to be missing the circular slide-rule portion. As I understand, that’s the part that simplifies the MOB and MOO calculations, the drift formulae, and makes the whole set work.April 11, 2022 at 2:59 pm #10571
You are quite right – my mistake. That eBay listing is missing the most important part!
Do keep an eye on eBay – they pop up on irregular intervals. I noticed a slightly beat up one that sold a couple of months ago.April 22, 2022 at 7:21 pm #10572
I’ll be looking. Was able to find a couple of good-shape N4-ES slide rules.
Hopefully one shows up. Thanks for the lead.May 2, 2022 at 8:21 am #10574
Polhemus computer on eBay: https://www.ebay.com/itm/125291199560?mkevt=1&mkpid=0&emsid=e11021.m43.l1120&mkcid=7&ch=osgood&euid=ef89c4e215fe464e9c13b67cd4c1910a&bu=45330740762&ut=RU&osub=-1%7E1&crd=20220502060827&segname=11021&sojTags=ch%3Dch%2Cbu%3Dbu%2Cut%3Dut%2Cosub%3Dosub%2Ccrd%3Dcrd%2Csegname%3Dsegname%2Cchnl%3DmkcidMay 5, 2022 at 12:13 am #10575
Sadly not for much longer, grabbed it the moment I saw it. Thank you Sir for helping me spot it!
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