NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Freiberger Trommelsextant errors
From: Jean-Philippe Planas
Date: 2012 Apr 15, 13:42 -0700
I have an image of a Freiberger certificate (770979) issued on May 11 1977 featuring the following corrections;
From: Wolfgang Hasper <wolfgang.hasper@web.de>
To: NavList@fer3.com
Sent: Sunday, April 15, 2012 8:51 PM
Subject: [NavList] Freiberger Trommelsextant errors
Jean-Philippe and Alex,
Here's the table from the sextant case (translated :o))
Angle ° Correction ''
0 0
10 +3
20 +13
30 +18
40 +25
50 +28
60 +36
70 +38
80 +46
90 +52
100 +50
110 +51
120 +48
It belongs to Freiberger Trommelsextant No. 080103 (w.
full sight mirror), bought early 2009, so likely
manufactured 2008.
plotted corrections are fairly well resembling a sine
curve, which is why I assume eccentricity as the main
source of error.
Any other ideas?
Wolfgang
From: Jean-Philippe Planas
Date: 2012 Apr 15, 13:42 -0700
Wolfgang,
Yes this is most likely the excentrity error .
I have an image of a Freiberger certificate (770979) issued on May 11 1977 featuring the following corrections;0
-2
+2
+2
-1
-5
-8
-10
-18
-21
-35
-45
-45
I am very surprised by these large values as Tamaya and C-Plath claimed far lower non correctable errors (for some models less than 10").
See below an array comparing different makes and providing the maximum theoretical non-correctable error as provided by the
manufacturer.
http://navastro.fr/tablocomp.html
JPP
| Marque | DAVIS | ASTRA | FREIBERGER | CASSENS & PLATH | TAMAYA | ||||||||
| Modèle | Mark 3 | Mark 15 | Mark 25 | III B DeLuxe |
III B Profess. |
Yacht | Drum "Pro" |
Profess. | Bobby Schenk | Polaris | Horizon Ultra | Jupiter MS-833 |
Spica MS-733 |
Image |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Châssis Matière Poids Rayon Couleurs |
Plastique 0,180 kg 180 mm G |
Plastique 0,410 kg 180 mm N |
Plastique 0,410 kg 180 mm G |
Aluminium 1,2 kg 153 mm N |
Alu./ Laiton 1,5 kg 153 mm N |
Aluminium 0,860 kg 142 mm B - M |
Aluminium 1,4 Kg 175 mm N - M - G |
Laiton 1,8 kg 165 mm N |
Laiton 1,8 kg 163 mm N - B (4) |
Laiton 1,8 kg 163 mm N |
Laiton 1,8 kg 163 mm N - B |
Alu./Laiton 2,0 kg 162 mm N |
Alu./Laiton 2,0 kg 162 mm N |
|
Optique Standard Option Tube ét. Datascope H. à bulle Fixation |
Œilleton non inutile non non Fixe |
3 x 27 non oui (std.) non non non std. |
3 x 27 non oui (std.) non non non std. |
(1) 3,5 x 40 7 x 35 oui oui oui Standard |
(1) 3,5 x 40 7 x 35 oui oui oui Standard |
2,4 x 25 non non non non Fixe |
4 x 40 8 x 30 non non non non std. |
(3) 3,5 x 40 7 x 35 oui oui oui Standard |
3,5 x 40 7 x 35 oui oui oui Standard |
3,5 x 40 7 x 35 oui oui oui Standard |
3,5 x 40 7 x 35 oui oui oui Standard |
4 x 40 7 x 35 oui oui oui Standard |
4 x 40 7 x 35 oui oui oui Standard |
|
Mir. index Type Dimension |
Face AR 34 x 29 |
Face AR 50 x 38 |
Face AR 50 x 38 |
Face AV 56 x 42 |
Face AV 56 x 42 |
Face AV 57 x 29 |
Face AV 57 x 42 |
Face AV 56 x 42 |
Face AV 58 x 43 |
Face AV 58 x 43 |
Face AV 58 x 43 |
Face AV 57 x 42 |
Face AV 57 x 42 |
|
Mir. hori. Type Dimension |
Tradit. 27 x 15 |
Tradit. 42 x 30 |
Pl. champ 42 x 30 |
(2) Tr. ou Pc Ø 51mm |
(2) Tr. ou Pc Ø 51mm |
Tradit. 57 x 29 |
Tr. ou Pc Ø 57mm |
(3) Tr. ou Pc. Ø 56mm |
Pl. champ Ø 58mm |
Clearview® Ø 58mm |
Pl. champ Ø 58mm |
Pl. champ Ø 57mm |
Pl. champ Ø 57mm |
| Eclairage | Non | Non | Standard | Standard | Standard | Option | Option | (3) | Standard | Standard | Standard | Standard | Standard |
| Filtres Index/horiz. Matière |
2 / 2 Plastique |
4 / 3 Plastique |
4 / 3 Plastique |
4 / 3 Verre |
4 / 3 Verre |
3 / 2 Verre |
4 / 3 Verre |
4 / 3 Verre |
4 / 3 Verre |
4 / 3 + astigmat. Verre |
3 / 2 + 2 polaris. Verre |
4 / 3 Verre |
4 / 3 Verre |
| Précision (fabricant) |
5' | 5' | 5' | 20" | 15" | 40" | 20" | 10" | 10" | 10" | 10" | 10" | 10" |
| Coffret Matériau Poids Outils Dragonne |
carton 0,370 kg inutiles Non |
Plastique 1,650 kg inutiles Oui |
Plastique 1,650 kg inutiles Oui |
Bois verni 4,2 kg Clé miroirs tournevis brosse Oui |
Bois verni 4,5 kg Clé miroirs tournevis brosse Oui |
Bois verni 2,6 kg Clé miroirs Oui |
Bois verni 4.3 kg Clé miroirs Oui |
Polyprop. 3,1 kg Clé miroirs chiffon brosse Oui |
(4) Bois Verni 5,5 Kg Clé miroirs chiffon brosse Oui |
Bois Verni 5,5 Kg Clé miroirs chiffon brosse Oui |
Bois Verni 5,5 Kg Clé miroirs chiffon brosse Oui |
Polyprop. 3,3 kg Clé miroirs chiffon Oui |
Polyprop. 3,3 kg Clé miroirs chiffon Oui |
From: Wolfgang Hasper <wolfgang.hasper@web.de>
To: NavList@fer3.com
Sent: Sunday, April 15, 2012 8:51 PM
Subject: [NavList] Freiberger Trommelsextant errors
Jean-Philippe and Alex,
Here's the table from the sextant case (translated :o))
Angle ° Correction ''
0 0
10 +3
20 +13
30 +18
40 +25
50 +28
60 +36
70 +38
80 +46
90 +52
100 +50
110 +51
120 +48
It belongs to Freiberger Trommelsextant No. 080103 (w.
full sight mirror), bought early 2009, so likely
manufactured 2008.
plotted corrections are fairly well resembling a sine
curve, which is why I assume eccentricity as the main
source of error.
Any other ideas?
Wolfgang
