Q. on Sextons and Priests

Discussions on all aspects of the The United Kingdom & its Empire and Commonwealth during the Inter-War era and Second World War. Hosted by Andy H
JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

Q. on Sextons and Priests

#1

Post by JonS » 25 May 2007, 05:57

When the British put the 25-pr in the Sexton, they lost about 2,400yds of range (from 13,400yds down to 11,000yds), due to the limits of elevation within the vehicle.

Range of the towed US 105mm M1 How was - from what I can figure - about 11,500m, and it had a max elevation of 65°. When this How was put into the M7 Priest the max elevation was restricted to 35°. What I cannot find is the range of the 105mm How when mounted in the M7. Since max elevation in the veh is considerably below 45° (theoretical optimum elevation for max range), I'd expect that max acheivable range is also considerably less than the towed version.

Does anyone have reliable info on the max range of the US 105mm How, in both its towed and SP incarnations?

Thanks
Jon

ChristopherPerrien
Member
Posts: 7051
Joined: 26 Dec 2002, 01:58
Location: Mississippi

#2

Post by ChristopherPerrien » 25 May 2007, 06:23

You could always park these SP guns on a slope to get the lost elevation back.So I doubt it was a major tactical problem.


JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#3

Post by JonS » 25 May 2007, 06:54

If that were the case, why did they bother increasing the elevation in the B2 model for korea (a country not noted for it's lack of slope)?

ChristopherPerrien
Member
Posts: 7051
Joined: 26 Dec 2002, 01:58
Location: Mississippi

#4

Post by ChristopherPerrien » 25 May 2007, 09:42

JonS wrote:If that were the case, why did they bother increasing the elevation in the B2 model for korea (a country not noted for it's lack of slope)?
:roll:
Its called an improvement. No use having to resort to a "field "expedient method" forever if a design flaw can be corrected. Also as to the original M7, I have seen pictures of some that carried "ramps" for extra elevation.

Now for the real DUH!!!!!!!!!
If you can locate a range card for a 105 M2A1 towed gun just look at how far it fires at 35 degrees. I looked for one but I could only find them for $$$$. And any of my books which might have this info are boxed up right now.

My guess is 8700 or 9700 meters max range for a WWII M7, it probably has been 25 years since I might have seen the fig. I'll through this out here just to see if I am close.Trivia pursuit you know :wink:

Regards,
Chris

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#5

Post by JonS » 25 May 2007, 10:31

ChristopherPerrien wrote:
JonS wrote:If that were the case, why did they bother increasing the elevation in the B2 model for korea (a country not noted for it's lack of slope)?
:roll:
Its called an improvement. No use having to resort to a "field "expedient method" forever if a design flaw can be corrected.
Cookie time for you.
If you can locate a range card for a 105 M2A1 towed gun just look at how far it fires at 35 degrees.
Thanks Einstein. If I could do that, I would have.
My guess is 8700 or 9700 meters max range for a WWII M7
Hurrah. Something useful! Even if it is only a guess :roll:

FWIW, I'm after the info for a game. HPS' PzC:N44 to be specific. I'm making some changes to the OoB file, and want to show the pros and cons of different equipments as fully as feasible. I know about ramps and expedients and what have you, but what I want for this is just the bog standard 35° = xx,000m.

Regards
JonS

User avatar
cbo
Member
Posts: 710
Joined: 15 Feb 2004, 19:23
Location: DK

Re: Q. on Sextons and Priests

#6

Post by cbo » 25 May 2007, 14:31

JonS wrote:When the British put the 25-pr in the Sexton, they lost about 2,400yds of range (from 13,400yds down to 11,000yds), due to the limits of elevation within the vehicle.

Range of the towed US 105mm M1 How was - from what I can figure - about 11,500m, and it had a max elevation of 65°. When this How was put into the M7 Priest the max elevation was restricted to 35°. What I cannot find is the range of the 105mm How when mounted in the M7. Since max elevation in the veh is considerably below 45° (theoretical optimum elevation for max range), I'd expect that max acheivable range is also considerably less than the towed version.

Does anyone have reliable info on the max range of the US 105mm How, in both its towed and SP incarnations?
As it turns out, a very good question :)

According to Hunnicutt: "This limitation on maximum elevation was to prove a disadvantage in combat, frequently requiring that the vehicle be parked on a steep ramp to obtain high angle fire". About the B2: "...the limitations imposed by the 35 degrees maximum elevation were once again apparent. The rugged Korean terrain required higher angles of elevation to place fire on the reverse slopes. The solution in the Italian mountains almost ten years before hand been to drive the vehicle onto a steep ramp to obtain the necessary angle."

So the problem with the limited elevation does not appear to have been limited range but rather the limitations on high-angle fire. Interestingly, the M7s reduced elevation was due to a percieved need to keep the vehicle as low as possible. A curious criteria for an SP howitzer intended for artillery use....

As for the ranges, the 105mm M2 had a max. elevation of 64 degrees 15 minutes and a range of 12200 yards. Its max. range was achieved at an elevation of 44 degrees. The latter info is from "The American Arsenal" entry on the M7 and seems rather meaningless, given that the elevation was 35 degrees max...?!?!

A bit of search found this: http://www.texasmilitaryforcesmuseum.or ... es/025.htm which claims a range of 11200 yards for the M7.

cbo

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

Re: Q. on Sextons and Priests

#7

Post by JonS » 25 May 2007, 22:52

cbo wrote: As for the ranges, the 105mm M2 had a max. elevation of 64 degrees 15 minutes and a range of 12200 yards. Its max. range was achieved at an elevation of 44 degrees. The latter info is from "The American Arsenal" entry on the M7 and seems rather meaningless, given that the elevation was 35 degrees max...?!?!
I would assume that's for the towed version.
A bit of search found this: http://www.texasmilitaryforcesmuseum.or ... es/025.htm which claims a range of 11200 yards for the M7.
OK, so that would indicate a loss of 1000yds when mounted in the M7.

Thanks
Jon

ChristopherPerrien
Member
Posts: 7051
Joined: 26 Dec 2002, 01:58
Location: Mississippi

#8

Post by ChristopherPerrien » 26 May 2007, 03:13

If you read the article that range is posted for a M7B model(Korea) which didn't have the elevation restriction of the WII M7.

Macadamia nut cookie please.

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#9

Post by JonS » 26 May 2007, 07:09

If I park the M7 on a hill and shoot at targets in the valley, do I get more range?

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#10

Post by JonS » 26 May 2007, 07:12

ChristopherPerrien wrote:If you read the article that range is posted for a M7B model(Korea) which didn't have the elevation restriction of the WII M7.

Macadamia nut cookie please.
No cookie for you. The B1 had the same elevation restriction, but was based on the Sherman chassis (rather than the Grant chassis). The B2 removed the elev restr.

User avatar
cbo
Member
Posts: 710
Joined: 15 Feb 2004, 19:23
Location: DK

#11

Post by cbo » 26 May 2007, 10:29

JonS wrote:
ChristopherPerrien wrote:If you read the article that range is posted for a M7B model(Korea) which didn't have the elevation restriction of the WII M7.

Macadamia nut cookie please.
No cookie for you. The B1 had the same elevation restriction, but was based on the Sherman chassis (rather than the Grant chassis). The B2 removed the elev restr.
But then again, the vehicle in the picture is clearly an M7B2 with the raised gun and MG turret. :)

But it wouldn't make any sense that the M7B2 had a lesser range than the towed 105mm gun, as it had the sam 65 degree elevation.

The confusion seems to come from the fact that the Texas Military Forces Museum has two M7s. The M7B2 in the link above and an M7B1 seen in this link http://www.texasmilitaryforcesmuseum.or ... es/030.htm . The good people at the museum have taken the shortcut of using the same text for both vehicles. So I think the range given is credible.

cbo

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#12

Post by JonS » 26 May 2007, 11:28

Ya, but the text relates to the B1 ;)

~11.5km for the towed and M7B2 is credible. Elsewhere*, I found a credible range for the M7/M7B1 given as 10500yds (about 9.6km).

Regards
JonS

* Pemberton, AL; ‘The Development of Artillery Tactics and Equipment’; 1950.

ChristopherPerrien
Member
Posts: 7051
Joined: 26 Dec 2002, 01:58
Location: Mississippi

#13

Post by ChristopherPerrien » 26 May 2007, 16:51

I found a credible range for the M7/M7B1 given as 10500yds (about 9.6km).
Ah ! so my guess of 9700 m was "about" dead on. Please send me a BIG cookie. :D

Chris

JonS
Member
Posts: 3935
Joined: 23 Jul 2004, 02:39
Location: New Zealand
Contact:

#14

Post by JonS » 26 May 2007, 22:05

Well, about 500m short if we take the avg, but sure: here have this buffalo cookie. It's perfect since it came from the same place as your guess ;)

Carl Schwamberger
Host - Allied sections
Posts: 10055
Joined: 02 Sep 2006, 21:31
Location: USA

#15

Post by Carl Schwamberger » 27 May 2007, 15:38

JonS wrote:If I park the M7 on a hill and shoot at targets in the valley, do I get more range?
Yes. and, if you shoot at a hill top or forward slope you get less range. When we computed firing solution we checked the elevation of the target and found the difference between that and the battery elevation. This was expressed as 'positive or negative Vertical Interval' and plugged into the computation. A change of a few meters elevation is enough to move the mean point of impact of the rounds outside the effective casualty radius. Had I time to burn I coud pull the book out and figger up a few examples.

This is what makes shooting at reverse slopes tricky. If the trajectory angle and the slope angle are anywhere close the rounds will sail over and into the valley floor. So the 2d Lt FDO has to pay attention to his map and check the trajectory charts in the back of the TFT (grumble).

Post Reply

Return to “The United Kingdom & its Empire and Commonwealth 1919-45”