Jump to content


Patton Troubles


  • Please log in to reply
24 replies to this topic

The_Chieftain #1 Posted Mar 04 2016 - 19:04

    Military Specialist

  • Administrator
  • 17566 battles
  • 10,001
  • [WGA] WGA
  • Member since:
    09-08-2011

Last week, we saw how Armored Board was not entirely happy with the T40 medium tanks which they had received for testing. Bearing in mind that the M46 entered production before Armored Board had even started testing T40, the testing was as much just to prepare Fort Knox for things to keep a particular eye out when they finally did get some M46s to play with. Some defects had been noticed by Aberdeen before Fort Knox received the vehicles, and some modifications incorporated. Some.

M46 #12 as it arrived. This tank survived the testing process. Note the name painted on the side.

These new M46 tanks showed up in the very beginning of 1950, Fort Knox immediately ceased the T40 testing program, parked the four vehicles, and set about the four M46s they received. The first thing they did was break them in gently, running about 200 road miles, and not exceeding 2,200 rpm. Then the testing started. Over the course of the test, the four tanks ran the following distances.

So, a reasonable testing period, with over 2,500 miles on the clocks of two of them by the time all was said and done.

There were a number of comparison tests done between M46 and the M26 predecessor,  with, in most cases, M46 performing better than M26.

More specifically, we have the following:

 

1)      Turning tests.

Three tests were performed. One was a simple, practical, “At various speeds, how much room does the outside track need in terms of turning diameter?” The figures were pretty close, with, for example, at 10mph, 76.3’ diameter for M46, and 73.5’ for the M26. Of course, M46 could neutral steer, which was a definite plus.

 

The second test was a 500 yard slalom, with flags to zig-zag around spaced 25-50 yards apart. The difference in time was  1:42 for the M46, 1:52 for M26. From the report: “No steering deficiencies were noted in operation of either vehicle during this test. The difference in time required to negotiate the course was due to the higher speed attained by the Medium Tank M46”. So far so good.

 

The third test was the “winding roads” test. Seriously, that’s the official name in the report. The course was a 2 ½ mile “winding gravel road having numerous sharp curves”, and an average grade of 3%. They timed the tanks going up, and going down.

 

M26 took an average of 10:12 to get up the course, and 6:05 to get down the course. They then tried with an M46. Getting up was about 6:49, a substantial improvement, but on the way down, “a loss of adequate steering control was apparent when the speed of the test vehicle exceeded the speed of its engine. i.e. when coasting downgrade.’

 

This is probably Army understatement in operation. It was apparent not least because  M46 #21 failed to make one of the turns, fell off a bridge, rolled over, immediately caught fire, and burned. This may have been a clue. The date was 16 March 1950.

Tank 21 did not survive the testing process. Even the gun tube bent. Curiously, the transmission was repairable.

 

They got another M46, ran that downgrade, but got a slower-than-M26 time of 6:47. This was explained by the report as follows: “In order to insure(sic) safe operation, the Medium Tank M46 was unable to take full advantage of its maximum speed when going downgrade, due to the extreme caution which had to be exercised by the driver to attain proper relative engine and vehicle speeds.” Given what happened the other tank, the extreme caution is understandable. This was only a problem going downhill; when travelling under full power upgrade, there was no issue. Remember that the crossdrive transmission conducts its steering mainly by use of power application, more than brakes. The driver’s immediate actions were first to rev the engine in order to increase the ratio of engine power to vehicle speed, then tried the brakes. Neither course of action worked. The driver was in such a state after his incident that he failed to pull the fire extinguishers before exiting, which was understandable from his perspective, but not necessarily helpful to the investigation and test process.

 

 There was a second problem identified at high speeds, that the vehicle had a tendency to oversteer. The sensitivity was such that when attempting to make a minor change in direction, the driver would inadvertently overcorrect, requiring additional correction, with the effect that the tank would fishtail down the road. A modification to the transmission fixed that one, though.

 

2)      Brake tests.

This one certainly came into M46’s favour, with the tank stopping from 20mph in 25’1”, and 30mph from 48’6”. The M26 stopped from 20 in 43’6”, and didn’t make it to 30mph. Even at 10mph, in reverse, the M46 stopped in 6’ less distance, 8’1”.

 

During the course of the brake testing period, the brakes on M46 #34 failed as it approached a bridge at a curve. It failed to make the turn, fell off the bridge, rolled over, immediately caught fire, and burned.  This was 15th April, 1950. Brake testing apparently failed.

And then there were two... Down to half the fleet now.

 

This was during an uphill run, so the same steering issue as the earlier tank was not considered to be a factor. Post-accident investigation indicated that a brake application strut had fallen out of alignment, and that application of both brakes actually resulted in application to the left brake only. An earlier such deficiency had been noted on another tank, with less dramatic consequences.

 

A memorandum in May to the Chief of Army Field Forces described the fact that both vehicles immediately burned when overturned as “quite disturbing.” In fairness, upside-down is not a naturally occurring position for a tank, and it is not incredibly surprising that the designers didn’t make much allowance for it. The conclusion was that the fire was started by oils falling from the auxiliary motor air cleaner being ignited by the external exhausts, and things went from there. This fire, fueled by additional leaking hoses, burned away the seals of the gas tank caps, resulting in the petrol then feeding the flames, and thus consuming the rest of the tank.

 

The two remaining intrepid tanks were brought along to a 60% grade for…

 

3)      Hill climbing tests.

Both M26s made it to the top of the slope in about two minutes twenty. The M46s got about this far.

 

 

 

Doubtless the hearts of the evaluators stopped. Fortunately, it turned out that it was just oil from the engine crankcase finding its way into the fuel system at angles. However, the root problem still remained: The tank couldn’t get up the hill due to a lack of power.

 

4)      Fording tests.

 

Possibly with some relief, given the amount of smoke and flames which had bedeviled the testing to that point, the Board took the tanks down to a creek with a depth of up to 48”. The tank wouldn’t catch fire there, would it?

 

Well, no, that’s just steam. In fact, it turned out that though the tank did continue to operate, it leaked a bit. Some 2’ of water entered the tank, so the driver got a tad damp.

 

The lubricants got washed off the engine generators, water got into the air cleaners and lubrication some of the running gear wheels,  and there was quite a bit of turbulence around the auxiliary motor, but other than that, the tank seemed to run fine.

 

5)      Mud driving. Between 12-40” of mud was tried, with both M46 and M26 performing about the same.  Both tanks bellied out in the mud at about 40” and got stuck.

 

6 & 7) Maximum speed and acceleration. Who doesn’t want to drag race tanks? (I’ve done the same in Abrams).

 

M46 leads the M26 in the cross-country race.

 

8) Night Driving

        This was a more subjective test, they just drove around in the dark to see how easy it was. There were a couple of quirks with the headlights, but the biggest concern was that the exhaust pipes and mufflers glowed in the dark, and could be seen at 500 yards with the naked eye, and 700 yards with hand-held infra-red. (Remember, this is 1950. IR technology was not particularly new).

 

Test 9 was an observation of the power system, and it generally passed, barring the lack of torque as evidenced by the inability to climb the grade.

 

Test 10 is driver comfort, a favourite of mine.

This was, again, a subjective test, with opinions being sought. One issue was the relative position of brake and accelerator pedals, which was rather inconvenient and apparently not fixed by the M47. Tall drivers in particular were not happy given the fixed seats, and nobody was happy that there was no support for the driver, meaning that he got thrown around as the tank bounced over rough ground.

 

11) Fuel and oil requirements.

 

 

All in all, there was a 9-page list of deficiencies, which you can see here. Fort Knox estimated that they were getting 3.7 miles to the man-hour of maintenance, mostly related to the oil cooling fans. Attempts were made to fix the cross-drive transmission to allow it to steer correctly, but it would end up that only a complete re-design at the factory would manage it.

 

Fort Knox was in two minds about issuing the vehicles out, even with the caveat that they be limited to 12mph in convoy operations. They wanted more field testing, and they wanted better tanks than M26, but on the other hand, there was a concern that if the M46 was released to troops in its then-state, that the troops would become prejudiced against M46 in all forms, even after the tank was fixed.

 

Again, it is worth recalling that M46 at this point is being churned off the assembly line. A letter dated 24 April 1950 indicates that if they wanted to get a particular change in the steering mechanism into the 500th M46, they had better tell someone by the 1st of May.

 

Now, this was obviously not the end of the testing. Field testing did continue with a line unit after this, the results of which I do not have.  However, it is clear that one of two things happened as a result of this initial testing: Either several hundred M46s were converted and left sitting around waiting for a fix to be developed before being issued to troops, or a couple of battalions’ worth of somewhat dodgy M46s were sent to the force.

 

Given that the M46(New) with the improved brakes, cross-drive transmission and a few other changes was scheduled for production in April 1951, and M46s entered combat in August 1950, it is evident which way the Army went, given the pressures of the Korean War. It would appear that the forces didn’t find too many 60% grades to fail to climb up, and there aren’t too many references to tanks falling off bridges so maybe they simply kept convoy speed down. Given that M46 was a general improvement over M26 as long as those two situations did not occur, it is unsurprising that overall the tank was welcomed.

 

As ever, my Facebook page remains here, my Youtube channehere, and Twitch stream (Every Tuesday at 4PM Pacific, and (very) occasional late evenings) is here. 



Hurk #2 Posted Mar 05 2016 - 22:20

    Major

  • Players
  • 59928 battles
  • 17,409
  • [KGR] KGR
  • Member since:
    09-30-2012
who would have thought tanks run poorly upside down? :) 

simba90 #3 Posted Mar 05 2016 - 23:49

    First lieutenant

  • Players
  • 20805 battles
  • 941
  • Member since:
    06-03-2012

View PostHurk, on Mar 05 2016 - 22:20, said:

who would have thought tanks run poorly upside down? :) 

 

IKR,

btw, I love your signature.



CedricMacLaren #4 Posted Mar 06 2016 - 01:13

    Major

  • Players
  • 16019 battles
  • 3,567
  • [RECKT] RECKT
  • Member since:
    02-24-2013
Could everyone escape via a bottom hatch when one rolled over and burned?

Pupsrus13 #5 Posted Mar 06 2016 - 01:51

    Corporal

  • Players
  • 6761 battles
  • 90
  • [SQKY] SQKY
  • Member since:
    07-10-2011
So when 9.14 comes out, the M46 is going to burn every time someone flips it?

GunnerOneFive #6 Posted Mar 06 2016 - 14:10

    Private

  • Players
  • 3218 battles
  • 2
  • Member since:
    08-23-2014
It sort of amazes me that it takes so long for any country to fix their combat vehicles. In WWI, the French had a submarine that was sent back to the dry dock 18 times, trying to fix some engine problems, and it never worked. How hard can it be to change the brakes to some that actually work? But here's the real question: If you watched the testing of the Patton, would you laugh or cry first? And I think that every tanks should be permanently on fire, just for dramatic effect. :amazed:

TRUMblestilskin #7 Posted Mar 06 2016 - 18:32

    Corporal

  • Players
  • 59731 battles
  • 81
  • Member since:
    01-26-2014
They should really make a map of Fort Knox since it has such a long history with tanks. But all we ever get is European/Russian maps :/ Oh, and I forgot North Africa...

Edited by StealthSabot, Mar 06 2016 - 18:36.


alexbuildit #8 Posted Mar 06 2016 - 19:09

    Sergeant

  • Players
  • 6389 battles
  • 102
  • Member since:
    06-30-2014
Lol. Great article.

zloykrolik #9 Posted Mar 07 2016 - 00:03

    Staff sergeant

  • Players
  • 41881 battles
  • 410
  • [RDTT2] RDTT2
  • Member since:
    05-05-2012

View PostStealthSabot, on Mar 06 2016 - 09:32, said:

They should really make a map of Fort Knox since it has such a long history with tanks. But all we ever get is European/Russian maps :/ Oh, and I forgot North Africa...

 

It is a little easier for a Russian company to get geographic data and pictures of Russian & European area than it would be for it to get the same for a US Army base.

 

"Excuse us plees. We are heer to take peektures of your army base."



Blackhorse_Nine_ #10 Posted Mar 07 2016 - 00:47

    Staff sergeant

  • Players
  • 7870 battles
  • 360
  • [HHT] HHT
  • Member since:
    08-06-2011

View Postzloykrolik, on Mar 06 2016 - 18:03, said:

It is a little easier for a Russian company to get geographic data and pictures of Russian & European area than it would be for it to get the same for a US Army base.

 

"Excuse us plees. We are heer to take peektures of your army base."

 

Can you say "Smell-ums" ?

 

I knew that you could ...



Legiondude #11 Posted Mar 07 2016 - 07:09

    Major

  • Players
  • 20761 battles
  • 23,198
  • [CMFRT] CMFRT
  • Member since:
    08-22-2011

Block Quote

 M46 #21 failed [...] fell off a bridge, rolled over, immediately caught fire, and burned.

Block Quote

 M46 #34 failed [...] fell off the bridge, rolled over, immediately caught fire, and burned.

 I'm sensing a pattern here...

 

 

 

 

 

 



NateKrool #12 Posted Mar 07 2016 - 17:44

    Corporal

  • Players
  • 10556 battles
  • 25
  • [BLAH] BLAH
  • Member since:
    02-16-2014

Maybe it was the repetition, but the phrase "rolled over, caught fire, and burned" sounds like a punchline to a variety of tank- or vehicle-related jokes.  Kind of like "took an arrow to the knee" and the like.

 

Sample:  I was doing really well.  Spotted upteen enemy tanks, got five kills, then went off a bridge, rolled over, caught fire, and burned.

 

Or maybe it just reminds me of an incident about a year or so ago.  Driving a Hummel on Mountain Pass from the south spawn, I drove East into the open field to fire up the Eastern road.  You know that shallow stream that runs through the field?  Well, at the time, there was a spot where the shallow stream suddenly becomes a deep river.  I drove across at this exact spot.  Left tracks on the shallow side.  Right tracks on the deep side.  The Hummel immediately rolled over onto its roof and the crew instantly drowned.



The_Chieftain #13 Posted Mar 07 2016 - 17:53

    Military Specialist

  • Administrator
  • 17566 battles
  • 10,001
  • [WGA] WGA
  • Member since:
    09-08-2011
Actually, it came pretty much straight from the report. Both tanks were reported as immediately burning after rolling over.

shapeshifter #14 Posted Mar 07 2016 - 18:43

    Major

  • Beta Testers
  • 17863 battles
  • 2,873
  • Member since:
    09-11-2010

 

View PostThe_Chieftain, on Mar 04 2016 - 13:04, said:


1)      Turning tests.

Three tests were performed. One was a simple, practical, “At various speeds, how much room does the outside track need in terms of turning diameter?” The figures were pretty close, with, for example, at 10mph, 76.3’ diameter for M46, and 73.5’ for the M26. Of course, M46 could neutral steer, which was a definite plus.

interesting on the turning numbers. Do you happen to know the M4's by chance? would make an interesting comparison.

 

Are those averages? or is it clockwise or counter-clockwise (for some reason some tanks seem to do better one way or the other)

cscottyd #15 Posted Mar 07 2016 - 19:17

    Private

  • Players
  • 10393 battles
  • 1
  • Member since:
    07-01-2012

View Postshapeshifter, on Mar 07 2016 - 17:43, said:

 

interesting on the turning numbers. Do you happen to know the M4's by chance? would make an interesting comparison.

 

Are those averages? or is it clockwise or counter-clockwise (for some reason some tanks seem to do better one way or the other)

 

If I remember correctly, most modern American tanks turn shorter to the right (so... clockwise, i  think). And, I believe this is the result, in part, to the vehicle having a shorter track on the right side. My Troop's BFVs usually had, on average, two less track shoes on the right track. This was also true in my experience with the M113 family of vehicles and the tankers said that their M1A2s were the same way as well.

 

I do not know the true reason for the shorter track but I have heard some pretty interesting ones... 

 

...because of the torsion bar suspension configuration.

...because of the difference in the torque from the transmission to the final drives.

 

And probably one of the best things I heard out of a soldier's mouth...

 

...so that the vehicle pulls to the right to prevent running into oncoming traffic during road marches if the driver dozes off!



Colddawg #16 Posted Mar 07 2016 - 19:24

    Major

  • Beta Testers
  • 45864 battles
  • 3,917
  • Member since:
    07-12-2010
I would think that would be problematic as the vehicle would always be pulling to the right.  Wouldn't this cause excessive wear on tracks and mechanisms as well?

qcarr #17 Posted Mar 07 2016 - 19:26

    Captain

  • Players
  • 28821 battles
  • 1,815
  • [REJCT] REJCT
  • Member since:
    11-22-2012
The M46 Patton turned out to be a pretty good tank in the end, and many prominent features first introduced in the M26/M46 tanks were important components of later M48s, M60s, and even the various iterations of Abrams.  But in hearing about the problems encountered during testing and knowing that the M46 continued to be a maintenance hog, it's easy to understand why most armored units in Korea preferred the Easy 8 once enemy tanks virtually disappeared from the battlefield.

The_Chieftain #18 Posted Mar 07 2016 - 19:37

    Military Specialist

  • Administrator
  • 17566 battles
  • 10,001
  • [WGA] WGA
  • Member since:
    09-08-2011

View Postcscottyd, on Mar 07 2016 - 18:17, said:

 

If I remember correctly, most modern American tanks turn shorter to the right (so... clockwise, i  think). And, I believe this is the result, in part, to the vehicle having a shorter track on the right side. My Troop's BFVs usually had, on average, two less track shoes on the right track. This was also true in my experience with the M113 family of vehicles and the tankers said that their M1A2s were the same way as well.

 

I do not know the true reason for the shorter track but I have heard some pretty interesting ones... 

 

...because of the torsion bar suspension configuration.

...because of the difference in the torque from the transmission to the final drives.

 

And probably one of the best things I heard out of a soldier's mouth...

 

...so that the vehicle pulls to the right to prevent running into oncoming traffic during road marches if the driver dozes off!

 

Torsion bar is correct. If you look at the Bradley or Abrams, you'll see that one roadhweel is further forward than the other, resulting in a shorter overall track length on the other side, because that side can 'cut the corner.' However, it's not a given. Abrams is 78 track links per side (when new tracks are installed: As the track stretches, one link can be removed without a requirement to remove one on the other side). Then again, the angle of the run from the idler to the near arm is much shallower than that of the Bradley or M113, so the corner-cut isn't as pronounced.

 

 



Legiondude #19 Posted Mar 07 2016 - 19:48

    Major

  • Players
  • 20761 battles
  • 23,198
  • [CMFRT] CMFRT
  • Member since:
    08-22-2011
Is it me or does the M46 seen in the first image seem a little sleek and low?

zloykrolik #20 Posted Mar 08 2016 - 03:37

    Staff sergeant

  • Players
  • 41881 battles
  • 410
  • [RDTT2] RDTT2
  • Member since:
    05-05-2012

View PostBlackhorse_Nine, on Mar 06 2016 - 15:47, said:

 

Can you say "Smell-ums" ?

 

I knew that you could ...

 

I still have my SMLM card.

 

I wonder if that phone number is still good?


Edited by zloykrolik, Mar 08 2016 - 03:42.





1 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users