re: M 10 GMC Turret Speed

[Centaur]

Could anyone advise me as to why the M10 Gmc has a slow turret.

As far as I understand the M10 was built with M3 components and had its armour lightened to increase speed. This would suggest the turret had less Mass than an M3 with the same rotating gear.

Which should produce at least comparable performance if not better. The extra mass of the 3" gun cannot be the cause of this slowing as the M3 76.2 mm has a fast turret the same as the M3 armed with a 75mm. If indeed the M10 did have a slower turret rotation speed who in the world designed it as it is inferior in tank hunting to the 76.2mm armed M3. Any advice or comments would be welcomed especially as playing British forces limits 3" gun deployment to the M10 GMC. Cheers

[Mr. Tittles]

An M36 (90mm) has a traverse speed of 15 sec/360 deg

[Centaur]

Thanks that sounds fast to me but maybee Im wrong. Of course the M36 could have uprated rotation gear but it was better armoured and carries a heavier gun. Anyone know the traverse speed of an M3 sherman for comparison. :confused:

[Centaur]

sorry M4 sherman got my Tank and gun labels muddled Im a muppet

[Redwolf]

The M36 had different turret gear.

I'm not at my books right now but the slow turret is correct according to Zaloga's M10 book IIRC.

[dalem]

Everything I've read makes special note of the fact that the 3" gun used for the M10 was a converted AA piece and extremely heavy. Because it was so heavy they needed to put those big counterweights on the rear of the turret. Hence the relatively slow traverse of the M10's turret.

The 76mm guns mounted in the Sherman series and Hellcat were purpose-built tank guns and as such much lighter.

-dale

[Redwolf]

No, it's the same gun.

The traverse mechanism is different. I need to get to my books.

[dalem]

Originally posted by redwolf:

No, it's the same gun.

The traverse mechanism is different. I need to get to my books.

Different guns. From Osprey's "U.S. Tank Destroyers in Action":

M10:

"The main armament of the vehicles was an M7 3 inch gun in an M5 mount..."

M18 (Hellcat):

"The M18 initially used the M1A1 gun which lacked a muzzle brake. Later, the M1A1C and M1A2 guns were employed."

I don't know if the M1A1/C/A2 guns were the same as in the M4 Sherman 76mm models, but I know that the M7 used in the M10 was NOT used in either the M4 Sherman or M18 Hellcat.

-dale

[Mr. Tittles]

Gun elevation was from +19 to -10 degrees and a highly trained crew could fire around 15 rounds per minute. There was no gun stabilization installed and both elevation and traverse were done by hand. Although it was a simple system, it was also very effective and typical of "quick firing" weapons of the time.

Looks like it was hand cranked!

[ December 17, 2003, 07:26 PM: Message edited by: Mr. Tittles ]

[Michael Emrys]

Originally posted by Mr. Tittles:

Looks like it was hand cranked!

That jibes with what I recall reading. If called for, I can do a bit of searching through my books to see what I can find out.

Michael

[von Lucke]

Supposedly the counter-weight on the rear of the turret weighed 2500lb's all by itself! Not the sort of thing easily cranked around by hand.

[Mr. Tittles]

76mm Gun M1A1, M1A1C, or M1A2 M1 in turret 45 rounds

(9 ready) 360°

(manual and hydraulic) 24°/sec

The M18 had a faster system. I believe the gunner had a grip that he could either turn clock wise or counter CW and the turret would turn in that direction. Depending on how far he turned the grip, it would vary the speed. Perhaps the M36 used a similar system.

[Mr. Tittles]

Picture 2:Picture 2:

Most of these scans are from the operator's manual for the M18. This one shows the left side of the open topped turret and the gunner's position. In these early turrets you will find on the right the M76 direct sight telescope. In the center right you can see the hydraulic traverse control handle and to the left the manual traverse handle with palm grip sticking up. The turret lock lever is to the lower left in the picture and just to the right of it, at the bottom of the hand traverse gear housing, is another small bar handle, this being the shift (low/high) for the traverse speed). Just below these controls can be barely seen the top of the first row of 76mm ammo, stored above the sponsons on each side of the vehicle. The storage bin at the top of the picture is labeled "Hand Grenades" and the edge of the main gun and shield are seen on the right. There was only a partial floor to the turret at the rear, the gunner had a small floor attached below and in front of him, with a firing pedal for the main gun.

[Harry Yeide]

The M10 lacked power traverse, which is the reason for the slow rotation. In theory, the driver was supposed to help by turning the vehicle if a major rotation was required and conditions allowed.

[Centaur]

Thanks guys. the only question is who in gods name accepted such a second rate solution to the problem or is that what the bow machine gunner did, must have arms like popeye. Thanks.

[Michael Emrys]

Most M10s produced didn't have bow MGs.

Michael

[Mr. Tittles]

Originally posted by Centaur:

Thanks guys. the only question is who in gods name accepted such a second rate solution to the problem or is that what the bow machine gunner did, must have arms like popeye. Thanks.

The vehicle, as a solution, is not as bad as the doctrine it was supposed to use in battle. The US TD doctrine was a knee jerk reaction to the Germans early war blitzkrieg tactics. Fleets of Panzers needed to be destroyed as they made thier daring thrusts on the battlefields. Battalions of US tank destroyers would hunt them down.

In reality, a company of TDs was usually attached to each US tank battalion, etc.

Gen. McNair, credited with the US TD policy, actually thought towed TDs were preferable and the M10 too expensive. This was some General from what I read.

As far as I know, US TDs did not have stabilizers. They were basically used in shoot n scoot type situations or ambush. In reality they were supposed to have the gun that enabled tank destruction. When the US Shermans sported 76mm guns, the M10 was just better than a towed weapon.

The M18 co-driver could actually steer the tank from his side of the hull. I dont know if other tanks/SPs had such a feature.

[Mr. Tittles]

http://www.lakemartin.net/~cfrench/tank_destroyers_history.htm

light reading

http://www.644td.com/stats1.htm

detailed M10 battalion stats

[ December 19, 2003, 09:10 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

The Army Historical Foundation TM

To Preserve the Heritage of the American Soldier

GEN Lesley J. McNair, USA

During World War II, a number of U.S. Army generals achieved fame and glory on the battlefields of the European and Pacific Theaters. Generals Douglas MacArthur, George S. Patton, Omar N. Bradley, Mark Clark, and many others won great victories against the Germans and Japanese. These victories, however, would have been impossible without well-trained troops. The man largely responsible for the monumental task of building and training the Army during World War II, and, in effect, largely responsible for its successes, was GEN Lesley J. McNair, the “brains of the Army” and commander of Army Ground Forces.

Lesley J. McNair was born on 25 May 1883 in Verndale, Minnesota. He graduated from West Point in 1904 and was commissioned in the Field Artillery. He served in Mexico as an artillery officer in both the Vera Cruz Expedition in 1914 and the Punitive Campaign in 1916. After the U.S. entered World War I in April 1917, McNair went to France in June of that year as a major with the 1st Division. He became closely associated with another officer in the 1st, George C. Marshall, and eventually became the senior staff artillery officer in the American Expeditionary Force Headquarters. At the close of the war, McNair held the rank of brigadier general and was the youngest general officer in the Army.

After the war McNair reverted to his permanent rank of major. His postwar assignments included teaching at the General Service School (1919-1921); staff officer in Hawaii (1921-1924); and professor of military science at Purdue University (1924-1928). After graduating from the Army War College in 1929, he served as assistant commandant of the Field Artillery School at Fort Sill from 1929-1933. Following an assignment with the Civilian Conservation Corps, McNair was promoted to colonel in 1935. Upon his promotion to brigadier general in March 1937, McNair assumed command of the 2d Field Artillery Brigade.

In April 1939, he became the commandant of the Command and General Staff College at Fort Leavenworth. During his tenure as commandant, war broke out in Europe. It soon became apparent that the U.S. would eventually be dragged into the conflict. Accordingly, the Army began to make some efforts to prepare for the coming war, particularly after the fall of France in June 1940. On 26 July 1940, the War Department activated General Headquarters (GHQ). Army Chief of Staff GEN George C. Marshall appointed McNair to be Chief of Staff, GHQ, which gave him the responsibility of training, organizing, and mobilizing the Army for war.

When he arrived in Washington on 3 August 1940, McNair had a monumental task before him. At that time, the Army consisted of eight understrength infantry divisions, one armored division, and one cavalry division. The National Guard’s eighteen divisions were also understrength, and the quality of Guard training ranged from fair to poor. Many officers had no more experience than the soldiers they were to command, leading McNair to declare the situation as “the blind leading the blind.”

With his small staff, McNair immediately set about making significant transformations to the training and organization of the Army. He stressed more realistic training, introducing live ammunition and other explosives into maneuvers. American troops would eventually expend over 240,000 tons of live ammunition in training exercises during McNair’s tenure. He also organized a series of large-scale training maneuvers in Louisiana, Tennessee, and the Carolinas. One of McNair’s most important decisions was to change the infantry division’s “square” (four regiments) structure to a triangular one (three regiments), primarily to increase the flexibility and mobility of the division by eliminating brigade headquarters and reducing the number of men per division.

On 9 March 1942, McNair, now a lieutenant general, became commander of Army Ground Forces (AGF) and continued with his efforts to improve the training and organization of the Army. During his tenure as AGF commander, the AGF reached its maxiumum strength of 2.2 million men. He traveled tirelessly around the country and overseas to observe American troops in training and in combat. In the spring of 1943, while observing troops in Tunisia, he was wounded by a German shell fragment.

In June 1944, McNair was posted to England to take command of the phantom 1st Army Group from Patton. While visiting the front again, he was killed by an errant American bomb during Operation Cobra near St. Lo, France, on 25 July 1944. He was the highest-ranking U.S. general killed in World War II. Tragically, his son, COL Douglas C. McNair, an artillery officer with the 77th Infantry Division, was killed in action less than a month later on Guam. McNair was posthumously promoted to general in 1954.

[Michael Emrys]

Originally posted by Mr. Tittles:

At the close of the war, McNair held the rank of brigadier general and was the youngest general officer in the Army.

I question this part. Patton also achieved the rank of brevet brigadier general and was born two years later (1885). There might have been others.

Michael