## 38,1cm Range Tables

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marty1
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Location: Seattle

### 38,1cm Range Tables

I have a question regarding the range table image posted below. The 50% Dispersion Zone is as the "50%ige Langenstreuung" curve. There is a backslash followed by a 50 in the title of the curve that has me scratching my head. What if anything is the / 50 supposed to imply?

Or -- let me try asking it this way. Does the 50% Dispersion Zone at 15,000-meters have a length of ~140meters? Does the 50% Dispersion Zone at 25,000-meters have a length of ~190meters?

Thanks a bunch.
marty Ulrich Rudofsky
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Or -- let me try asking it this way. Does the 50% Dispersion Zone at 15,000-meters have a length of ~140meters? Does the 50% Dispersion Zone at 25,000-meters have a length of ~190meters?
That sounds ok but I still don't know what '/50' is. Send me the text ...... Ulrich

marty1
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Location: Seattle
Thanks Ulrich. Check your email. Let me know if you can figure out was the"/50" means.

regards
marty

Ulrich Rudofsky
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I think "/50 [Dm]* simply means "per 50 hectometers". (50x10=500 Dm=50 hectometer). I hope this means something to you, because this stuff is beyond my range.

Glossary for above graph:
[Title:] 38.1 cm
G=weight 875 kg; Vo = 745 m/s
Luftgewicht = air density 1.245 kg/m e3

Geheim = Secret

Erhöhungswinkel psi [*] = angle of elevation psi times 10
Fallwinkel omega [*] = trajectory (fall) angle omega time 10
Endgeschwindigkeit Ve [Dm/s] *) = final velocity Ve [Dm/s]
Flugzeit = time of flight [s]
50% ige Längsstreuung/50 [Dm] *) = 50 % longitudinal scatter/50 [Dm] *)
Bestrichener Raum R [Dm] *) = sweep space R [Dm] *)
Bestrichener Raum R für 10 m Zielhöhe und 30 m Zielbreite = Sweep space R for 10 m target height and 30 m target width
Entfernung [hm] = distance [hectometers = m x 100]
*) Dm = Dekameter, i.e., scale must be multiplied by 10

In reference to the attachment 3 graph it says in the text:

"The distance E (hm) is taken from the firing table (see example of the firing table graphics attachment 3). Furthermore, several estimated distances for a given target as well as the resulting impact angles for this distance are obtained from the firing table in order to calculate the necessary velocity for borderline, that is, intact penetration. These data are entered into the same graph to complete the curve. The first curve demonstrates the actual available velocity, the second curve [demonstrates] the velocity necessary for the penetration. The intercept of both curves determines the distance from which a penetration is still likely. A 50 by 50 hm interval calculation for both velocity curves is sufficient. Here is an example:

At E = 100 hm, omega = 7 degrees according to the graph of the firing table. Consequently alpha = 90 deg. – 7 deg. = 83 deg. For this impact angle, the limiting velocity is now determined from the penetration curve for 350 mm KC (limiting velocity, since the hit is against a barbette!). This results in Vg = 390 m/s. In the same way, points for 50, 100, 150 hm are determined. The determined points result in the Vg curve. The penetration distance E is derived from the intercept of both velocity curves as E = 243 hm. Hence, the barbette will be penetrated up to this distance."

George Elder and I translated the entire article a couple of years ago, but I don't know where it was posted. Draft copies are available via e mail.
Ulrich

marty1
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Location: Seattle
Thanks Ulrich. It seems an odd way to present dispersion data. I'm going to go with my gut and assume the the curve presents 50% Zones as per my previous post -- i.e. the 50% Zone at 15000meters range has a length of about 140meters.