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United States Military Vehicle General: Guns, G*vins, and Gas Turbines

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3 hours ago, Karamazov said:

This XM-1 was with hydropneumatic suspension?

I think only the Geneal Motors protoype had a hydropneumatic suspension. According to Hunnicutt the Chrysler prototype had a torsion bar suspension.

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2 hours ago, XDrake said:

I think only the Geneal Motors protoype had a hydropneumatic suspension. According to Hunnicutt the Chrysler prototype had a torsion bar suspension.

 

Wasn’t the General Motors pilot vehicle better in testing as well?

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The General Motors prototype had hydropneumatic suspension on the first, second and last roadwheels, and torsion bars in the middle.

This curious arrangement also shows up in the South Korean K1 Type 88 tank, and is one of several reasons I suspect the South Korean design is a derivative of the General Motors design.

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3 hours ago, Conner Webb said:

 

Wasn’t the General Motors pilot vehicle better in testing as well?

 

According to soldiers involved in the XM-1 testing, the GM prototype was more popular and actually performed better than the Chrysler version. 

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23 minutes ago, Jim Warford said:

 

According to soldiers involved in the XM-1 testing, the GM prototype was more popular and actually performed better than the Chrysler version. 


Interesting.  Do you know any further details?

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15 hours ago, Collimatrix said:

The General Motors prototype had hydropneumatic suspension on the first, second and last roadwheels, and torsion bars in the middle.

This curious arrangement also shows up in the South Korean K1 Type 88 tank, and is one of several reasons I suspect the South Korean design is a derivative of the General Motors design.

 

The K1 does look very similar too the GM XM-1 as well. Wasn’t the K1 being designed around the same time that the GM vehicle was being tested?

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1 hour ago, Conner Webb said:

 

The K1 does look very similar too the GM XM-1 as well. Wasn’t the K1 being designed around the same time that the GM vehicle was being tested?

 

No, the ROKIT program that became K1 was designed substantially later, and actually subcontracted mostly out to GDLS - the inheritors of the Chrylser Defense group that designed the M1.

 

16 hours ago, Collimatrix said:


Interesting.  Do you know any further details?

 

Army liked the GM's armor layout, FCS, and ability to fit the 120mm. But they *really* had a hankering for the Turbine powerplant of Chrysler's offering. So they basically came out and said they wanted a hybrid tank that was mostly like GM's but with the turbine drivetrain. Chrylser's offer to redesign their machine won the bid over GM's redesign, helped by Chrysler having some political favoritism.

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18 hours ago, TokyoMorose said:

 

No, the ROKIT program that became K1 was designed substantially later, and actually subcontracted mostly out to GDLS - the inheritors of the Chrylser Defense group that designed the M1.

 

 

Army liked the GM's armor layout, FCS, and ability to fit the 120mm. But they *really* had a hankering for the Turbine powerplant of Chrysler's offering. So they basically came out and said they wanted a hybrid tank that was mostly like GM's but with the turbine drivetrain. Chrylser's offer to redesign their machine won the bid over GM's redesign, helped by Chrysler having some political favoritism.

 

This is pretty much my understanding as well.  After the initial testing in July of 1976, Sec of Defense Rumsfeld issued a statement saying that they were delaying the decision until both vehicles were designed to accommodate either engine option and 120mm capable turrets.  This decision was basically a huge boost to Chrysler, since it meant that both companies saw each other's hand, to use a card playing metaphor.  With the extra time given, the Chrysler team did everything in the power to reduce the cost of their vehicle, while GM stood pat for the most part.  This gave Chrysler the edge they needed.  Also, Chrysler desperately needed this contract, GM was less excited about it.  It would probably be fair to say that GM was doing the government a favor by being in the contest, since it meant that the government could have a competition.  I think GM's excitement about building tanks was not all that high after the MBT-70 fiasco. Teledyne Continental Motors however really wanted GM to win so their engine could go into production.  Losing to the gas turbine pretty much sealed teledyne Continenal's fate.

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2 hours ago, Walter_Sobchak said:

 

This is pretty much my understanding as well.  After the initial testing in July of 1976, Sec of Defense Rumsfeld issued a statement saying that they were delaying the decision until both vehicles were designed to accommodate either engine option and 120mm capable turrets.  This decision was basically a huge boost to Chrysler, since it meant that both companies saw each other's hand, to use a card playing metaphor.  With the extra time given, the Chrysler team did everything in the power to reduce the cost of their vehicle, while GM stood pat for the most part.  This gave Chrysler the edge they needed.  Also, Chrysler desperately needed this contract, GM was less excited about it.  It would probably be fair to say that GM was doing the government a favor by being in the contest, since it meant that the government could have a competition.  I think GM's excitement about building tanks was not all that high after the MBT-70 fiasco. Teledyne Continental Motors however really wanted GM to win so their engine could go into production.  Losing to the gas turbine pretty much sealed teledyne Continenal's fate.

 

From the Army's perspective, redoing the contest after both teams (purely because the army was going to mandate the turbine and did want that change to be done after signing the GM contract) had seen each other's solution gave them the best possible deal from their perspective, Chrysler's final winning proposal was everything they wanted. It's been said Chrysler needed the contract badly, but considering GM's tank branch up and closed shop immediately after losing the M1 contract, I have to imagine they were just as badly in need (Chrysler still had the Patton family for defense revenues...). It's amusing in a certain way that the winner of the contest in both cost and performance was knocked out of the running because of incredibly optimistic views of the turbine as the superior engine of the future. They had estimated lower costs, less maintenance, growth to 2000hp, and other idealistic views.

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12 hours ago, Collimatrix said:

FWIW, I think growth of the AGT-1500 to 2000 HP would be fairly straightforward.  As I understand it, the thing is already downrated to 1500.  There would likely be some cost to engine life.

 

Whats the power and torque curve and delivery like compared to the Diesel contemporaries that other tanks use? The main point people say about the M1 is that the AGT-1500 is far superior too Diesel engines but is that even really true?

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5 hours ago, SH_MM said:

Diesel%20vs%20Gas%20Turbines%20dyno%20sh

 

1 hour ago, roguetechie said:

That actually does look pretty damn commanding when you're talking about doing tank like things in a tank sized vehicle.

 

The biggest issue isn't so much the turbine's performance itself - which does live up to the promises, but rather that the Turbine is only compatible with the X1100 transmission, which sadly is not terribly good. Of all the transmissions they did calculations on, it was the worst performing (particularly bad on downshifts).

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Makes sense, no need to hire a helicopter to deliver the explosives.

 

On 7/29/2018 at 6:33 PM, SH_MM said:

Diesel%20vs%20Gas%20Turbines%20dyno%20sh

 

Interesting that they're comparing to a pretty beefy MTU 883. Presumably a 1500-horse diesel would look even worse

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http://www.thedrive.com/the-war-zone/22621/the-army-wants-armored-turrets-packing-120mm-mortars-for-its-strykers-and-other-vehicles

 

US Army wants 120 mortars for its Strykers, this time turreted ones, with direct fire capability (sort of like NEMO).

It's not exactly new info, but it's a good sign that it's not a dead project.

 

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I wonder if it's from seeing that Polish Rosomak variant during exercises.

 

From the market survey.

 

Quote

Significant 120mm Mortar FIFT system performance requirements include:


- Caliber: 120mm smooth bore (Threshold)
- A Minimum Range of 200m (Threshold) for Indirect and Direct Fire and 50m (Objective) for Direct Fire.
- A Maximum Range of ≥ 8,000m (Threshold) to 20,000m (Objective).
- Ammo Preparation: Automated storage and processing of ammo from fiber packing container (Objective)
- Mission Computation/Gun-Laying: Automated calculation of tactical and technical fire direction and gun lay (Threshold)
- Loading/Firing: Automated loading of round into gun tube from intermediate tray or ready rack and fire-on-command (Threshold). Ammo transitions from stowage through the firing event without human contact (Objective).
- Response Time of Initial Receipt: 30 seconds after receipt of fire mission if emplaced, 60 seconds after receipt of fire mission if moving (Threshold)
- Response Time of Fire and Move: Capable of accepting fire missions, firing and moving up to 750 meters on dry, hard surfaces within 90 seconds of identifying a potential enemy (Threshold) and "shoot on the move" (Objective) capability.
- The mission computation, gun laying, ammunition preparation and firing is Semi-autonomous (Threshold) or autonomous (Objective) computation of tactical and technical fire direction, automatic gun lay, preparation of the ammunition for firing, and firing of the mortar round.
- Munitions Family: Fire the full 120mm Family of Munitions (FoM) with modifications (Threshold) or be able to fire the 120mm FoM with no modifications and capable of handling to be determined (TBD) projectiles up to 40lbs and 40inches length (Objective).
- Fields of Fire: Must allow for firing from the platform in any direction within a 360 degree (6400 mil) arc (Objective).
- Lethality- Engagement Profile: Must be capable of Line of Sight (LOS) engagements to destroy moving or stationary light armored vehicles up to a maximum range of 500m (Threshold) to 4000m (Objective)
- Lethality- Massing Fires: Must be capable of firing Multiple Round Simultaneous Impact (MRSI) missions, with 6 rounds impacting/functioning within 4 seconds (first to last round) (Threshold) to 12 rounds impacting/functioning within 4 seconds (first to last round) (Objective).
- Lethality- Rate of Fire: Must provide a Maximum Rate of Fire (MROF) of at least 16 rounds per minute at maximum increment for 1 minute followed by a sustained rate of fire (SROF) of 6 rounds per minute at maximum increment indefinitely (Threshold). It is desired that the weapon be capable of being fired at the MROF of 24 rounds per minute for 2 minutes and maintain a SROF of 12 rounds per minute indefinitely (Objective).
Per the above requirements, the 120mm FoM include the following items:
- The M934/M934A1 HE, M930/M930E1 ILLUM, M929 SMK (Threshold);
- The M931 FRPC, M933 HE, M57 HE, M983 IR ILLUM, M91 ILLUM (Objective)
Per the above requirements, the 120mm FoM, shall be compatible with the following fuzes:
- The M734/M734A1 MOFA, M935 PD (Threshold)
- The M776 MTSQ, M745 PD, M524/M524A1 PD, M772 PD/MTSQ, M84 TIME, M567 PD, M532 PRX, M783 PD/DLY, M751 PD (Objective)

 

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