zIFBoards - Free Forum Hosting
Fully Featured & Customizable Free Forums

Learn More · Sign-up Now
Welcome to Nsdraftroom. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Name:   Password:


Pages: (3) [1] 2 3  ( Go to first unread post )

 Tank engine
Forza
Posted: Aug 26 2011, 11:07 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



This is a little project of mine that I've been working on for a while. This is my plan A; plan B was to use a turbine engine but after a bit of research I found that it would actually work towards the opposite of what I wanted.

What I want: I'm trying to think of designing an engine that can run on the bare minimum amount of fuel. I do realize that many nations in NS probably don't think to RP realistic resource amounts and most NSers don't know what the term peak oil is. However, because I want to do something different (and my girlfriend is working longer hours...) I took it upon myself to create an engine which would be suited to an environment where oil is at a premium.

Yeah, the write up for this is huge and I don't expect anybody to read it. However I know there are parts which will be flawed so I'd appreciate if someone who knows their stuff about engines would weigh in on a few points, maybe offer some better ideas. I'm only one and a half years through a five year degree so I can accept I don't know everything.

I might, might, market this when the faults are ironed out. Might.

Sumer, I'd appreciate your views and expertise.

Forza GreenTank Project

Introduction

The Forza GreenTank project is a design study to create a propulsion system for an Armoured Fighting Vehicle operating where carbon-based fuel is at a premium. GreenTank uses technologies that have been pioneered on race cars, small passenger cars and diesel-electric trains to work towards a fuel consumption goal of 1.5 Litres per kilometer.

Internal Combustion Engine

The Forza HDrive uses two internal combustion engines. Each is a Flat-6 unit displacing a relatively small 8 litres, forcibly inducted by Forza's eCharge aspiration system and teamed with Forza's HybriDrive technology which altogether creates the hybrid diesel-electric drivetrain.

Due to requirements to use a hybrid drivetrain, the engines needed to be kept physically small to maximise available space in order to fit the generators and battery packs required for the hybrid system. This led to the demand for a small-displacement engine which would keep external dimensions to the minimum and that would also be more efficient than a larger engine when at light load, such as speeds above idle. Maximum power produced by the ICE does not need to be as high to equal other vehicles for power to weight ratio, as the power provided by the motor generators in parallel to the ICE would be sufficient to address the diffence in power levels.

The two Flat-6 engines are stacked on top of one another to form what resembles a flat-H engine, except with no mechanical connection between the two crankshafts.

The engine has a specific output of 52 kw per litre, to put this into perspective the HDrive engine yields roughly the same amount of power per litre compared to the FB-12TSD which powers the AY2-1E Panthera Tigris MBT, one of the most powerful engines ever fitted to an MBT, despite consuming half of the fuel. The output is a product of the engine's low compression ratio, relatively high maximum engine speed and very high staged boost levels which are explained later. Each cylinder displaces 1,333 cubic centimetres. The total power of just the two ICE's alone is a mere 832kw however the hybrid system can contribute an extra 800kw to this total when the engine is at it's maximum output, giving a total output of 1632kw or over 2150 horsepower.

The engine block itself is made from aluminium alloy, comprised of 11% silicon, 4% manganese and 0.5% magnesium. This Al-Alloy has a high thermal conductivity and hence is able to dissipate heat quicker than cast iron. Also, it leads more thermal efficiency, cooler running engines and are lighter thereby improving the overall vehicle’s operative characteristics.

Combined with the more efficient fuel burn and the increased flexibility of the forced induction system, this drivetrain increases specific power while reducing fuel consumption.

Low Compression Ratio

The engine itself makes use of an extremely low compression ratio of 14:1, putting it on equality with the lowest compression diesel engines fitted to passenger cars and possibly the lowest ever seen on an AFV. Diesel engines generally have a very high compression temperature and pressure at piston top dead center. If fuel is injected under these conditions, ignition will take place before an adequate air-fuel mixture is formed, causing heterogeneous combustion to occur locally which essentially results in an inefficient combustion reaction.

When the compression ratio is lowered, compression temperature and pressure at top dead centre decrease significantly. Consequently, ignition takes longer when fuel is injected near top dead centre which allows for a more desireable mixture of air and fuel. This alleviates the formation of NOx and soot because the combustion becomes more uniform throughout the cylinder without localized high-temperature areas and oxygen insufficiencies. Furthermore, injection and combustion close to top dead centre result in a highly-efficient diesel engine, in which a higher expansion ratio is obtained than in a high-compression-ratio diesel engine, thus meaning the engine can produce more force with a single stroke.

Due to its low compression ratio, the maximum in-cylinder combustion pressure for this diesel engine is lower than other typical heavy diesels which allows for significant weight reduction through structural optimization, essentially lightening the engine where possible and reducing it's exterior dimensions. Because the stresses placed on the cylinder block by compression are much less than other diesels, the engine does not need to be engineered to withstand these forces and thus weight and exterior size can be shedded.

Also due to the lower combustion ratio, internal componenets such as the crankshaft were also able to be adapted due to a lesser stroke being required. This in particular reduces mechanical friction by a considerable percentage. Because the internal components and the engine block have much less stress placed upon them, they are able to last longer than components of other diesel engines, which results in not only a more fuel efficient engine but also one which is more reliable.

Cold starting and misfiring

There are only two primary problems that have been preventing the spread of low-compression-ratio diesels in modern applications regardless of their numerous advantages. The first is the fact that when the compression pressure is reduced, the compression temperature during cold operation is too low to cause combustion, which means the engine cannot be started. The second is the occurrence of misfiring during warm-up operation due to lack of compression temperature and pressure.

Forza engineers decided that the problem of a reduced compression temperature could be fixed by simply altering the amount of fuel injected when the engine is starting, thus calling for a variable fuel injection system which would be electronically controlled. The newly adopted multi-hole piezo injectors allow for a wide variety of injection patterns and can inject fuel in increments of 10^-9 of a litre and at temepratures of up to 2000 bar. Precision in injection amount and timing increases the accuracy of mixture concentration control which means the engine can start in all conditions no matter how cold the temperature is.

Ceramic Fast Glow Plugs developed by NGK also help the cold start capability. As opposed to a metal pin-type glow plug, the heating coil of a ceramic glow plug has an especially high melting point. It is also sheathed in silicon nitrite, an extremely robust ceramic material. The combination of the heating coil and ceramic sheath enable higher temperatures and extremely short preheat times due to excellent thermal conductivity. Also, ceramic glow plugs have a more compact design. This is important, because there is very little free space in today’s engines. NGK NHTC glow plugs achieve a temperature of 1,000°C in less than two seconds and can after-glow for more than ten minutes at temperatures of up to 1,350°C. Optimum combustion is ensured even at low compression ratios. In addition, the NHTC glow plug can glow intermediately to prevent cooling of the particle filter in deceleration phases.

The commonrail fuel injector is capable of a maximum of 9 injections per combustion, injecting at up to 2000 bar in very precise amounts. Along with the three basic injections: pre-injection, main injection, and post-injection, different injection patterns will be set according to driving conditions which are controlled and governed automatically by the engine control unit. Definite engine-start even with a low compression ratio is attributable to this precise injection control and also the adoption of ceramic glow plugs.

Any misfiring that may occur during warm-up operation after engine-start is prevented by adopting a variable valve timing system for the exhaust valves, similiar to the one seen on other Forza engines. From studying diesel engines, it was noted that just a single combustion cycle is sufficient for the exhaust gas temperature to rise. Given this, the exhaust valves are opened slightly during the intake stroke to regurgitate the hot exhaust gas back into the cylinder, which increases the air temperature. This promotes the elevation of compression temperature which in turn stabilizes ignition and greatly reduces if not eliminates the chance of a misfire.

Dual engine layout

The use of two seperately controlled internal combustion engines is designed to reduce the fuel consumption and emissions of an internal combustion engine during light load operation. In typical light load driving the driver uses only around a quarter to a third of an engine’s maximum power. In these conditions, the throttle valve is nearly closed and the engine needs to work hard to draw air for combustion. This causes an inefficiency known as pumping loss. Some large capacity engines need to be throttled so much at light load that the cylinder pressure at the zenith of the cylinder is approximately half that of a small engine half the size. Low cylinder pressure means low fuel efficiency and fuel consumption begins to sky rocket.

Deactivating one engine at light load means there are fewer cylinders drawing air from the intake manifold which works to increase its fluid (air) pressure. Operation without variable displacement is wasteful because fuel is continuously pumped into each cylinder and combusted even though maximum performance is not required. By shutting down effectively half of vehicle's cylinders the amount of fuel being consumed is much less. Between reducing the pumping losses which increases pressure in each operating cylinder and decreasing the amount of fuel being pumped into the cylinders. Fuel consumption for large capacity Forza engines can be reduced by 20 to 35 percent in highway conditions.

The two internal combustion engines are identical flat-6 engines designated #1 and #2 as discussed above. One engine is designated the primary engine while another is designated as the secondary; due to wear and tear issues, the designations switch automatically on the hour to ensure an adequate amount of down time for each engine.

The primary engine will operate whenever the tank is not relying on battery power for movement or to provide power to the systems which make up the tank. The secondary engine only activates on demand; ie when the primary engine can not sustain the amount of power required by the vehicle at the present time.

Each ICE is connected to a motor/generator as will be discussed later. The two engines power the generator which stores the energy created in the battery packs, relying on the remaining electric motor/generators to convert the electrical energy into motion.

Forced Induction

The GreenTank project debuts Forza's eCharge system, using electrically powered compressors to forcibly aspirate the engine rather than using exhaust powered turbochargers or mechanically driven superchargers. The eCharge system is not only more efficient than typical methods, but the lesser number of moving parts in extreme conditions also improves the reliability of the system.

Each engine mounts two compressors; one for each bank of cylinders, amounting to a total of four for this particular drivetrain. The system also mounts a total of two turbines which are used to recollect energy from the exhaust gases.

Using ultra-high voltage wires to minimize power loss, stored battery power is transferred to a series of electric motors in one of the system's compressors. There, the motors are used to accelerate the compressor to full operating speed to ensure the maximum amount of boost is available. The Forza EMS (Engine Management System) controls the air flow rate and boost pressure via control of the compressor speed which allows for a precise and effective fuel flow rate for combustion.

The compressors used are Variable Geometry Turbochargers which are well suited to diesel engines and were first used by Forza on the Corio series of commercial truck. VGT's allow the effective aspect ratio of the turbo to be altered as conditions change. This is done because optimum aspect ratio at low engine speeds is very different from that at high engine speeds. If the aspect ratio is too large, the turbo will fail to create boost at low speeds; if the aspect ratio is too small, the turbo will choke the engine at high speeds, leading to high exhaust manifold pressures, high pumping losses, and ultimately lower power output. By altering the geometry of the turbine housing as the engine accelerates, the turbo's aspect ratio can be maintained at its optimum. Because of this, VGTs have a minimal amount of lag, have a low boost threshold, and are very efficient at higher engine speeds. VGTs do not require a wastegate.

At high engine speeds there is more energy generated by the turbine than is required by the compressor. Under these conditions, the excess energy can be used to recharge the energy storage for the next acceleration phase or used to power some of the auxiliary loads such as an electric air conditioning system.

The system can operate in what is commonly known as a 'steady state,' where the power produced by recycling the energy from the exhaust gases through the exhaust turbines matches the power consumed by the compressors. This prevents the system from draining the batteries.

Signature Reduction

Exhaust fumes and gases are passed out the rear of the tank, through a double muffler and particle filter. Exhaust gases are diluted with outside air to reduce their heat signature. This is done by sucking air through a small inlet flush against the tank and mixing the cool outside air with the exhaust gases. Exhausted and outside air meet in a special Y tube, with a radiator being mounted on the stem of the Y, sucking air from both stems through to the exhaust.

Sound-deadening engine covers are also fitted to the engine to reduce the noise both inside and outside the cabin. Forza engineers are particualrly ardent at reducing the NVH of large luxury cars but found the same basic principles applied to armoured vehicles. Double-insulated sound covers are placed in a box to cover the engine, which is itself mounted on springs to quell vibrations. The top of this box can be easily removed to lift the whole engine out. As a result, the AY1 is much quieter inside and out than any other MBT.

Hybrid Drivetrain

The Forza HybriDrive replaces a normal geared transmission with an electromechanical system. Because an internal combustion engine (ICE) delivers power best only over a small range of torques and speeds, the crankshaft of the engine is usually attached to an automatic or manual transmission by a clutch or torque converter that allows the driver to adjust the speed and torque that can be delivered by the engine to the torque and speed needed to drive the wheels of the car. For classification purposes, the gearbox can be described as an Electronic Continuously Variable Transmission, or EVT.

The HybriDrive system replaces the gearbox, alternator and starter motor with a three-phase brushless alternator serving as a generator, two powerful motor-generators, a computerized shunt system to control the afforementioned devices, a mechanical power splitter that acts as a second differential, and a battery pack that serves as an energy reservoir. The motor-generator uses power from the battery pack to propel the vehicle at startup and at low speeds or under acceleration. The ICE may or may not be running at startup. When higher speeds, faster acceleration or more power for charging the batteries is needed the ICE is started by the motor-generator, acting as a starter motor.

When the operator wants the vehicle to slow down the initial travel of the brake pedal engages the motor-generator into generator mode converting much of the forward motion into electrical current flow which is used to recharge the batteries while slowing down the vehicle. In this way the forward momentum regenerates or converts much of the energy used to accelerate the vehicle back into stored electrical energy.

The sole purpose of the brushless alternator is to convert mechanical energy generated by the ICE and convert it into electrical energy which is stored in the battery pack. In addition, by regulating the amount of electrical power generated, the alternator also controls and regulates the transmission of the vehicle by changing the internal resistance of the alternator. The pair of motor generators drive the vehicle in tandem with the ICE. The two roles are not interchangeable. When the four motor generators are in operation, they create an extra 800kw of power between them.

The two ICE are geared independantly to the EVT transmission where their power and torque is combined and then split.

The mechanical gearing design of the system allows the mechanical power from the ICE to be split three ways: extra torque, extra rotation speed, and power for an electric generator. A computer program running appropriate actuators controls the systems and directs the power flow from the different engine and the electric motor sources. This power split achieves the benefits of a continuously variable transmission (CVT), except that the torque/speed conversion uses an electric motor rather than a direct mechanical gear train connection. The vehicle cannot operate without the computer, power electronics, battery pack and motor-generators, though in principle it could operate while missing the internal combustion engine.

The transmission contains a planetary gear set that adjusts and blends the amount of torque from the engine and motors as it’s needed. Special couplings and sensors monitor rotation speed of each track and the total torque on the tracks, for feedback to the control computer.

Advantages of a Hybrid

In summary, the HybriDrive system works by the brushless alternator feeding electric power to the battery pack where it is stored, before it is supplied to the two motor generators which rectify the electric energy into mechanical energy, where it is then used to drive the tracks. Furthermore, during normal operation the engine can be operated at or near its ideal speed and torque level for power, economy, or emissions, with the battery pack absorbing or supplying power as appropriate to balance the demand placed by the driver. During stoppages the internal combustion engine can be turned off for a greater fuel economy.

Two other advantages are made possible by this set up.

The first is "Stealth Mode," where the vehicle can travel at slow to medium speeds without using the ICE for power, thus running silently. This gives an assaulting force an enourmous advantage as an enemy will generally not be able to hear the AFV approaching, except over rough ground which would cause noise. However, the absence of an engine note will mean that the noise of the tracks on the ground alone will not alert the enemy to the presence of an AFV. In this mode, the alternator spins freely and the engine is de-coupled from the rest of the drivetrain. Stealth Mode can be run for up to fourty minutes or fifty kilometres running off the battery power. After this, the ICE will need to recharge the battery pack.

The second is the "Overboost" function. When accelerating, the vehicle teams the powerful ICE with the pair of motor-generators to combine their power and torque, resulting in a huge boost to acceleration. The Overboost function can also be employed for the vehicle to act as a tug, by either pushing or pulling an otherwise immobile vehicle, up to an eighty tonne MBT, to a safer position.

The drivetrain can also be programmed to switch off the ICE and rely soley on electric power when travelling for periods of time at constant speeds to conserve fuel. Although this doesn't do much to help fuel economy during combat manuevers, a great amount of fuel can be saved when the vehicle is (not sure how to word this part, basically whenever the tank is cruising but not in an area where the speed is likely to fluctuate greatly). In a world first for a tank, the ICE is fitted with a start/stop mode which automatically kills the engine when the engine comes to idle to conserve fuel further. If the engine is still set to "on," the driver simply needs to increase the throttle and the engine will quickly restart, or the engine will automatically restart when the reserve battery power dips below 10%.

Credit goes to:
General Electric
Detroit Diesel-MTU Australia
Siemens
Mazda
Volkswagen
Toyota
NGK
Borg Warner
And any other source I used for research that I have forgotten.


--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
Lamoni
Posted: Aug 26 2011, 11:09 AM


Most Consistent Desginer (2012)


Group: Admin
Posts: 3,774
Member No.: 336
Joined: 25-April 08



As I said in the tank thread on NS, i'd be interested in retrofitting these into Lamonian tanks, if the engine system works out.


--------------------
QUOTE
Stevid: Well, you must be congratulated for creating an arsenal ship that hasn't been torn to shreds by the NSD Naval community. I've seen many arsenal ships go through here and been laughed at, but you've gone and designed one that everyone seems at least half okay with.  Well done.


QUOTE
Lyras: Competence-wise, an M-21 would comfortably be a match for the vast majority of NS-grade tanks.


QUOTE
Yanitaria: Compared to you, most designers look like they have ADD.


QUOTE
Ekraysia: I have to say, comparing your military equipment to that of the average NSer would be like comparing the T-34 to a hastily up-armoured elderly horse.


QUOTE
<Anemos> Sometimes I can't help but wonder if you're on a design team of some sort
Top
Forza
Posted: Aug 26 2011, 11:18 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



QUOTE (Lamoni @ Aug 26 2011, 11:09 AM)
As I said in the tank thread on NS, i'd be interested in retrofitting these into Lamonian tanks, if the engine system works out.

Hopefully it's alright. What I've done isn't exactly clever or outrageous; I've just researched existing technologies which companies hope will extend the life of the ICE before petrol or diesel is no longer used to power cars and trucks etc. Obviously I've been sensible about it and I don't think I'm using anything that wouldn't work in a tank application, however a second opinion would be great.


--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
no endorse
Posted: Aug 26 2011, 05:31 PM


You have way too much time on your hands ...


Group: Moderators
Posts: 4,236
Member No.: 22
Joined: 11-April 07



Low compression ratio does not increase engine efficiency (not in the thermodynamic sense). What you're attempting to do with homogenous combustion can be achieved with HCCI engines. Since you're running this thing electric drive, possibly not a bad choice? (And since it's NS you can claim the problems have been worked out, though a guy I know that's doing some of that engineering thinks they're 5-10 years out atm because of the control side)
http://en.wikipedia.org/wiki/Homogeneous_c...ession_ignition



Boost doesn't increase efficiency of the base engine. It allows you to use a smallish engine with good burn characteristics in the cruise and idle ranges, but with significantly more top end power than would be otherwise possible. (efficient at idle, power at high RPM) Thus, I'm not sure the low RPM range supercharger is helping you achieve good fuel burn characteristics. I might go with an electric turbocharger instead. That lets you spool up the compressor from your batteries to give you great acceleration, and lets you operate the turbine on its own as a generator while cruising or idling.
http://en.wikipedia.org/wiki/Hybrid_turbocharger


--------------------
user posted image
user posted image
QUOTE (IRC)
[22:39]Spizania: A chain is a unit of length; it measures 66 feet or 22 yards or 4 rods or 100 links[1] (20.1168m). <<< This is why Britian ruled the world
[22:39]Spizania: we created a system of measurements noone else could understand
QUOTE
[17:57] matinsky theres only one thing that can save saxon england
[17:57] matinsky ...
[17:57] matinsky ...
[17:57] Rosdivan Frogs?
[17:57] matinsky a mark XXXIII bolo
Top
Forza
Posted: Aug 27 2011, 01:52 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



QUOTE
Low compression ratio does not increase engine efficiency (not in the thermodynamic sense). What you're attempting to do with homogenous combustion can be achieved with HCCI engines. Since you're running this thing electric drive, possibly not a bad choice? (And since it's NS you can claim the problems have been worked out, though a guy I know that's doing some of that engineering thinks they're 5-10 years out atm because of the control side)


I thought the HCCI engines (which I use extensively in my passenger cars under the guise of ACR technology) were limited to running on petrol since they are essentially diesel engines which run on unleaded?

Lowering the compression ratio isn't the cause for greater efficiency, but it does permit a better fuel injection pattern which does increase the efficiency. In the sense, this engine is a commonrail diesel turned up to 11. At the beginning of 2012, Mazda will debut it's range of low compression diesel engines which I heavily based this engine off.

QUOTE
Boost doesn't increase efficiency of the base engine. It allows you to use a smallish engine with good burn characteristics in the cruise and idle ranges, but with significantly more top end power than would be otherwise possible. (efficient at idle, power at high RPM) Thus, I'm not sure the low RPM range supercharger is helping you achieve good fuel burn characteristics. I might go with an electric turbocharger instead. That lets you spool up the compressor from your batteries to give you great acceleration, and lets you operate the turbine on its own as a generator while cruising or idling.


I will definitely give the electric turbocharger a look; I hadn't considered it before as such. Thanks for the heads up.


--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
no endorse
Posted: Aug 27 2011, 03:00 AM


You have way too much time on your hands ...


Group: Moderators
Posts: 4,236
Member No.: 22
Joined: 11-April 07



You might not want to run straight 87 octane gasoline through an HCCI engine, it might require a new (and very precise) blend, but yes, it needs high octane number fuel.

QUOTE
I will definitely give the electric turbocharger a look; I hadn't considered it before as such. Thanks for the heads up.

They're incredibly nifty, and can be really flexible. They're probably better known as "hybrid turbochargers" or something silly like that.


--------------------
user posted image
user posted image
QUOTE (IRC)
[22:39]Spizania: A chain is a unit of length; it measures 66 feet or 22 yards or 4 rods or 100 links[1] (20.1168m). <<< This is why Britian ruled the world
[22:39]Spizania: we created a system of measurements noone else could understand
QUOTE
[17:57] matinsky theres only one thing that can save saxon england
[17:57] matinsky ...
[17:57] matinsky ...
[17:57] Rosdivan Frogs?
[17:57] matinsky a mark XXXIII bolo
Top
Hurtful Thoughts
Posted: Aug 27 2011, 03:13 AM


100% Armaments Designer, now what?


Group: Members
Posts: 6,390
Member No.: 29
Joined: 11-April 07



Well, the ultimate end is to have a nuclear-powered (thorium) heavy-tank and electricly operated drone-tanks.


--------------------
Top
Vault X
Posted: Aug 27 2011, 03:23 AM


Designer


Group: Members
Posts: 6,583
Member No.: 937
Joined: 16-July 10



This writeup rises a number of yellow flags, but I'm not sure enough to comment. Probably needs a check by Sumer.

In regard to hybrid drivetrain, even a turbine tank running on a road is seriously loud. You don't even hear the engine much through the sound of tracks crushing tarmac and banging against one another.


--------------------
user posted image
Top
Forza
Posted: Sep 14 2011, 08:02 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



Still waiting Sumer wink.gif When ever you get a sec, even a brief glance would be fine.


--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
Lamoni
Posted: Sep 14 2011, 10:03 AM


Most Consistent Desginer (2012)


Group: Admin
Posts: 3,774
Member No.: 336
Joined: 25-April 08



Probably best to NSD PM him, tbh.


--------------------
QUOTE
Stevid: Well, you must be congratulated for creating an arsenal ship that hasn't been torn to shreds by the NSD Naval community. I've seen many arsenal ships go through here and been laughed at, but you've gone and designed one that everyone seems at least half okay with.  Well done.


QUOTE
Lyras: Competence-wise, an M-21 would comfortably be a match for the vast majority of NS-grade tanks.


QUOTE
Yanitaria: Compared to you, most designers look like they have ADD.


QUOTE
Ekraysia: I have to say, comparing your military equipment to that of the average NSer would be like comparing the T-34 to a hastily up-armoured elderly horse.


QUOTE
<Anemos> Sometimes I can't help but wonder if you're on a design team of some sort
Top
Sumer
Posted: Sep 14 2011, 10:29 AM


You have way too much time on your hands ...


Group: Admin
Posts: 6,060
Member No.: 8
Joined: 10-April 07



QUOTE (Forza @ Sep 14 2011, 04:02 AM)
Still waiting Sumer wink.gif When ever you get a sec, even a brief glance would be fine.

When I had time, it completely slipped my mind (I do that, a LOT). I'm going to post-it on my monitor to do tonight or sometime soon.


--------------------
QUOTE
“I believe that the sound of racking the pump of a shotgun is universally recognized as ‘kiss your ass goodbye’."

Proudly Canadian
user posted image
QUOTE ("L3 Communications")
Well...next to Sumer's juggernaut of death, the MCA-7G.
Top
Forza
Posted: Sep 14 2011, 10:56 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



QUOTE (Sumer @ Sep 14 2011, 10:29 AM)
QUOTE (Forza @ Sep 14 2011, 04:02 AM)
Still waiting Sumer  wink.gif When ever you get a sec, even a brief glance would be fine.

When I had time, it completely slipped my mind (I do that, a LOT). I'm going to post-it on my monitor to do tonight or sometime soon.

Thanks a heap for donating your time, Sumer. It's very much appreciated.


--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
Sumer
Posted: Sep 16 2011, 12:07 AM


You have way too much time on your hands ...


Group: Admin
Posts: 6,060
Member No.: 8
Joined: 10-April 07



Ok, what I have.

I don't think you will be getting that power from that displacement as you expect. 96hp/L is really high from a diesel, almost impossibly so. Conventionally, and this is a fairly conventional (All things considered, it's not balls-out-crazy).

A thought though, going with a V8 over a V12, just for size issues.

Anyway. Before I go any further, I would suggest putting more power emphasis on the electric motors of the hybrid drive. A combination of smaller main engine, APU and regenerative braking would give you enough charge to run a diesel-electric type hybrid drive. Leaving the electric motors to do the heavy lifting.

I like the use of lower compression ratio, however I want to stress you will lose multi-fuel capability. Most AFV diesels have high compression ratios to provide flexibility in fuel and fuel quality, and on top of that often have forced ignition. You will be sacrificing that.

I am very much against cylinder deactivation. Especially in something like an AFV. Diesel-Electric hybrid removes the need for it, and is vastly more efficient.

I can't see that kind of power/displacement ratio on this. I'd cut it in half, at leasy, before I'd consider it. That said, there are lots of ways to go green. One I have been playing with (You may steal this) is to copy the M59 in terms of layout (For an APC, but you can adapt the idea to a tank without the layout) with two smaller engines. Except they run generators, charging batteries, which in turn run electric motors. With a tank, and what is effectively tank based CODEADE, you can run one engine under light load to keep the batteries charged, two to top it off when running heavy. And have variable torque and power on the tracks. But that's my suggestion.


--------------------
QUOTE
“I believe that the sound of racking the pump of a shotgun is universally recognized as ‘kiss your ass goodbye’."

Proudly Canadian
user posted image
QUOTE ("L3 Communications")
Well...next to Sumer's juggernaut of death, the MCA-7G.
Top
Forza
Posted: Sep 17 2011, 12:10 AM


36% Armaments Designer


Group: Members
Posts: 724
Member No.: 1,006
Joined: 22-October 10



QUOTE
I don't think you will be getting that power from that displacement as you expect. 96hp/L is really high from a diesel, almost impossibly so. Conventionally, and this is a fairly conventional (All things considered, it's not balls-out-crazy).

A thought though, going with a V8 over a V12, just for size issues.


You're right, I was a little overzealous with the specific output.

I considered using a V8, V12 and a V16, the latter being ruled out due to it's larger size and the need for batteries, generators etc. I thought about using the V8 but I'm not sure if the low compression ratio tech will suit the large cylinders. Hence the V12 was chosen as an each-way bet. Stemming from your idea later, I may drop the V12 for two half displacement V8's.

QUOTE
Anyway. Before I go any further, I would suggest putting more power emphasis on the electric motors of the hybrid drive. A combination of smaller main engine, APU and regenerative braking would give you enough charge to run a diesel-electric type hybrid drive. Leaving the electric motors to do the heavy lifting.


I didn't think I'd need an APU if I had batteries as well as the main ICE? I like the idea of cutting the size of the ICE while uprating the electric motors so I'll do that when I update it. Regenerative braking is one idea I didn't think to use on a tank, would it work as well as it does on a car?

QUOTE
I like the use of lower compression ratio, however I want to stress you will lose multi-fuel capability. Most AFV diesels have high compression ratios to provide flexibility in fuel and fuel quality, and on top of that often have forced ignition. You will be sacrificing that.


Yes, losing the multi-fuel capability was one of the issues I faced and since I didn't know how to fix it, I just swallowed the loss. I have an adaptive compression ratio system which I use on my consumer cars however it wouldn't be suited to something with large cylinders.

QUOTE
I am very much against cylinder deactivation. Especially in something like an AFV. Diesel-Electric hybrid removes the need for it, and is vastly more efficient.


Might I ask why? How is cylinder deactivation different in principle from having two engines as you suggested later?

QUOTE
I can't see that kind of power/displacement ratio on this. I'd cut it in half, at leasy, before I'd consider it. That said, there are lots of ways to go green. One I have been playing with (You may steal this) is to copy the M59 in terms of layout (For an APC, but you can adapt the idea to a tank without the layout) with two smaller engines. Except they run generators, charging batteries, which in turn run electric motors. With a tank, and what is effectively tank based CODEADE, you can run one engine under light load to keep the batteries charged, two to top it off when running heavy. And have variable torque and power on the tracks. But that's my suggestion


I do like that idea so I'll have a play around with it and see if I can work something out.



--------------------
Qui Patitur Vincit - Who perseveres, conquers.

You'll Never Walk Alone
Top
Sumer
Posted: Sep 17 2011, 02:05 PM


You have way too much time on your hands ...


Group: Admin
Posts: 6,060
Member No.: 8
Joined: 10-April 07



QUOTE (Forza @ Sep 16 2011, 08:10 PM)
I considered using a V8, V12 and a V16, the latter being ruled out due to it's larger size and the need for batteries, generators etc. I thought about using the V8 but I'm not sure if the low compression ratio tech will suit the large cylinders. Hence the V12 was chosen as an each-way bet. Stemming from your idea later, I may drop the V12 for two half displacement V8's.

I'd almost go so far as to suggest dropping for two flat-6s.


QUOTE (Forza @ Sep 16 2011, 08:10 PM)
I didn't think I'd need an APU if I had batteries as well as the main ICE? I like the idea of cutting the size of the ICE while uprating the electric motors so I'll do that when I update it. Regenerative braking is one idea I didn't think to use on a tank, would it work as well as it does on a car?

Slap regenerative braking on the sprockets and you're going to have an awesome ammount of return power generation. It will work better, as opposed to simply having a difference between wheels and car, you have the entire track furface involved, and the tank.

As for APU, it never hurts. Especially if it means you can keep the batteries topped up, and if you need to quickly top the batteries because of over-powering the motors, it can cut in and add that little extra generating power.

QUOTE (Forza @ Sep 16 2011, 08:10 PM)
Yes, losing the multi-fuel capability was one of the issues I faced and since I didn't know how to fix it, I just swallowed the loss. I have an adaptive compression ratio system which I use on my consumer cars however it wouldn't be suited to something with large cylinders.

I'd suggest taking the hit in ICE fuel efficiency and upping the compression ratio so that you can burn more fuels. Especially if fuels become scarce, burning different kinds will keep your tank running longer.

An aside to this, as a tank overall, is building the fuel system to run from several sets of fuel tanks, with individual fuel systems through a controller that can be programmed to best use different kinds of fuels comming from different sources. The T-80 does this to an extent (Manual control of fuel feed), and can literally carry up to six different kinds of fuel in six different sets of tanks. Abrams, Leopard, and so on, have two tanks or four tanks on a common system.

QUOTE (Forza @ Sep 16 2011, 08:10 PM)
Might I ask why? How is cylinder deactivation different in principle from having two engines as you suggested later?

With cylinder deactivation, when you shut one cylinder down you are still moving it, not just losing the power it generates, but taking power to keep it moving. And on top of that, you keep wearing down the internal parts. The more you shut down, the worse this gets as long as part of the engine is still running.

with two engines, you shut one down, it's not taking or generating any power, and not wearing down.

On a car, where you are limited in a lot of ways, and will only have one engine, I can see it being useful. On an AFV, you have more freedom to have two engines to get better results.


QUOTE (Forza @ Sep 16 2011, 08:10 PM)
I do like that idea so I'll have a play around with it and see if I can work something out.

Be my guest.


--------------------
QUOTE
“I believe that the sound of racking the pump of a shotgun is universally recognized as ‘kiss your ass goodbye’."

Proudly Canadian
user posted image
QUOTE ("L3 Communications")
Well...next to Sumer's juggernaut of death, the MCA-7G.
Top
0 User(s) are reading this topic (0 Guests and 0 Anonymous Users)
0 Members:
« Next Oldest | Miscellaneous Sector | Next Newest »
DealsFor.me - The best sales, coupons, and discounts for you

Topic OptionsPages: (3) [1] 2 3 



Hosted for free by zIFBoards* (Terms of Use: Updated 2/10/2010) | Powered by Invision Power Board v1.3 Final © 2003 IPS, Inc.
Page creation time: 0.1647 seconds | Archive