Proposal: Updated Vehicles

[mmartin798]

Originally Posted by Desert Mariner

Standard features/equipment includes:
--200kV fusion power plant
--Drive motors (1 per wheel) - 3-phase, 6-pole AC internal permanent-magnet motor producing 192 kW (258 hp) and 429 Nm (317 lbf-ft) of torque (≈70kg each) [equivalent to Tesla Model S motor]

Just a couple things I noticed and have questions on.

First, I will assume its a 200kW fusion power plant. I know, just a typo.

Second is the drive motors. As shown, assuming you can power all the motors, the total torque of the truck is 1716 Nm (1268 lb-ft) since I am assuming your specs are per in-wheel motor. The gas turbine in the M1 Abrams generates 2750 lb-ft of torque. So you have about 50% of the torque and only 30% of the mass of a M1 Abrams. That would make this thing a beast. But the power plant can only supply 25% of the power to run all four motors at maximum output. So either your motors are too big or you intend to run each motor at a lower power level for redundancy in case of a single motor failure to not lose performance. This should be clarified.

[ChalkLine]

Should project vehicles have slat armour kits?

[Desert Mariner]

Originally Posted by ChalkLine

Should project vehicles have slat armour kits?

The RW versions of these vehicles can accept multiple "kits" of add-on armor so, I see no reason slat armor couldn't be added. The question then becomes how do you adjust the armor values?

I modeled a composite armor (from an online e patent) based on a forum post by Capt Gideon (sp?) and it came out at 150+ (the transparent armor windows were over 100) vs the 40-50 based on 4e rules.

[Desert Mariner]

Originally Posted by mmartin798

Second is the drive motors.

So, I was concentrating on weight and spaced the total power. This brings up a question on project fusion plants. Per TM1-1, they go up to at least 1000kW @ 1kg per kW but there's no mention of volume. Based on weight of the ICE engine and transmission, I've got about 950kg to work with, which means up to a 950kW plant but is that realistic? And yes, the intent is for redundancy so that failure of 1 motor doesn't disable the vehicle. I'd guestimate that normal operation would be around 70-80% of max per motor.
And I admit that the motors I modeled may be overpowered in the aggregate as they are intended to function. This is why I'm inviting input from the group, many of which are likely smarter about EV power and other aspects than I am.

[mmartin798]

Originally Posted by Desert Mariner

This brings up a question on project fusion plants. Per TM1-1, they go up to at least 1000kW @ 1kg per kW but there's no mention of volume.

Yeah, this is a frustrating thing, but there is no easy answer. The 1kg/kW is true on the low end. The 1MW (1000 kW) reactor, if we assume the weight range corresponds with the power output listed in the description, weights 5000kg or 5kg/kW. So the more power it generates, the heavier it is per kW. Maybe the higher reaction rates require greater shielding for the flux of fast neutrons. This is the primary reason in my game, the portable reactors run on He3 and not H2 (D). He3-He3 fusion produces zero neutrons and therefore require minimal shielding. I assume there are D-D reactors in the Project, but they have a tech to strip out the He3 before it fuses to produce fuel for the portables.

But TM1-1 mentions heavy water as fuel for a portable reactor, so they are D-D or D-T reactors which are not aneutronic reactions.

[Desert Mariner]

Without details such as amperage, voltage, etc. it’s seemingly impossible to properly size motors powered with a fictional fusion power plant.

I did find that for Tesla motors the Max. Motor Power (output kW) equals approximately 162% of the Max. Battery Power (input kW). This was explained in a 2012 Tesla.com forum post as follows:

“Here is is simple layman explanation. Without the technical electrical limitations stuff.
You have an electric motor that has a specific amount of power. You have a car that this motor is in. Obviously this motor doesn't have infinite RPM climbing possibilities . Being an electric though, means you have all that power available to you the second you hit the accelerator.
But now lets put this into context.
At rest, all that power gives you the torque that the model S has so far been praised for. "AT REST" and let me add "CLIMBING". This power gets the MS to say 100mph. Now think of it, if something was turning at 16,000rpm from rest to get you to 100mph as quickly as possible (considering weight..etc), do you realize that unless it starts turning at say 20,000rpm; it gets to a point where turning at 16,000rpm stops having as noticeable an affect on a car already doing 100mph as compared to one that was at rest. At that point, there is no need to even draw that much power anymore considering the car is already going "fast" all you have to do is draw enough power to make it go faster and at a more relaxed pace.
At 100mph, and being held there... the MS may actually be drawing less power cause it doesn't need to draw that much power to get itself up to speed and only needs to intermittently draw just enough juice to maintain your current speed. Think of it as using you hand to spin a fixed bicycle wheel, to get it up to speed you constantly apply force to the wheel, at say two turns every second. Once up to speed though, all you need to do is turn it once every 20 seconds to maintain that current speed.”

If this is applied directly to a 200kW fusion plant (input), the total drive motor output available would be approximately 326kW. Thus, I propose changing the drive motors as follows:

MTV 4x4 ICE engine produces 370hp (276kW) and 925ft-lb.
MLV motor produces 275hp (205kW) and 925ft-lb.

MTV (4x4): To match the ICE hp output, we need four (4) 70kW (94hp) electric motors producing a total output of 280kW (375hp), drawing a total of 172kW (input).

MLV (4x4): To (nearly) match the ICE hp output, we need four (4) 50kW (67hp) producing a total output of 200kW (268hp), drawing a total of 123kW (input). Alternatively, the 70kW motors above could be utilized.

MLV (6x6): To match the ICE hp output, we need six (6) 50kW (67hp) producing a total output of 300kW (402hp), drawing a total of 184kW (input).
Torque for individual motors would be 250ft-lb (339N-m), giving the 4x4 models a total of 1000ft-lb (1356 Nm) and the 6x6 models 1500ft-lb (2033 Nm). Since the 6x6 variants tend to be heavy haulers (i.e. wreckers, dump trucks, line haulers, etc.) I see no reason to “create” a separate motor with lower torque.

[StainlessSteelCynic]

I can't really add anything to the discussion about power source or electric motors but in the spirit of brainstorming, it might be worth looking at the LeTourneau company (and discussions about them) for information about electric drives. They've been in the business of manufacturing large vehicles with electrically powered wheel motors since the 1960s.

Granted their tech is focussed on earth-moving and construction vehicles and the electrical generation is typically done by a diesel generator but there's a few gems of info to be found in websites that discuss the company or their products. For example, there's been mention on a few websites that the diesel electric configuration is very quiet and it's probably safe to assume that Project vehicles would have the same level of stealth (or better) but that is something that is rarely mentioned (if ever) in any Project material that I've read.
The hybrid drive that LeTourneau used is reasonably common for various heavy plant so it might be worth checking other companies as well like Komatsu and so on.

[Desert Mariner]

Thanks for the resource.

I think I may have found an answer in an older forum (What Fusion Power means to the Project) post by mmartin798. He suggested using Moog in hub motors. The DB-22000-E he suggested may be a bit overpowered torque wise (understatement) but I think it's close enough for now.

Moog DB-22000-E Brushless DC Motor

• Size: 12.7cm (D) x 13.081 cm (frameless)
• Weight: 82.1kg
• Input: 16kW
• Peak Output: 2539 ft-lb (3442Nm)

The thread also discussed the need to provide vehicle power but didn't arrive at any conclusions. Moog also manufacturers in hub alternators so, I'd pair the above with:

Moog AG-5250-F-2ES

• Size: 13.335cm (D) x 5.969 cm (frameless)
• Weight: 25.63kg
• Output: 3590W / 259V continuous

This gives as 107.73kg per hub. In keeping with the original post, increase the total mass to 130kg and double the size to account for frame, sensors, etc.

[mmartin798]

I remember that discussion. I was basing much of that on the Oshkosh Defense HEMTT A3 that used their ProPulse hybrid diesel-electric drive train. The HEMTT A3 only uses one motor per axle rather than one per wheel. The one motor per axle approach may be better for a mine resistant vehicle, since the motor will be behind armor.

[nuke11]

Originally Posted by StainlessSteelCynic

For example, there's been mention on a few websites that the diesel electric configuration is very quiet and it's probably safe to assume that Project vehicles would have the same level of stealth (or better) but that is something that is rarely mentioned (if ever) in any Project material that I've read.

I've been working on a spreadsheet of "sound levels" dB for different events, areas, equipment, weapons and vehicles for the TMP.

Now from my research a eMotorcycle is 60 dB, eSnowmobile is 62 dB, average gasoline car is 70 dB, HMMWV is 77 dB. So I was thinking an MPV would be around 58 to 62 (still not completely set on that value yet).

[Desert Mariner]

[QUOTE=nuke11;81030So I was thinking an MPV would be around 58 to 62 (still not completely set on that value yet).[/QUOTE]

From what I've read recently, the EV is virtually silent below 10km/h and ICE is about 10db louder. Above that, the sound levels converge rapidly as the majority of the sound is aerodynamic (wind) and tire noise rather than from the engine/transmission.