Jump to content
Sturgeon's House

Recommended Posts

20 minutes ago, Xoon said:

I don't really see the advantage to this design. 

What about a Ethanol powered Turbocharged V12?

Nowhere in the rules does it state that it needs to be diesel. And a ethanol engine would blow other engines out of the water when it comes to power density. Also, I would consider ethanol as more progressive and environmentally friendly, fitting for such a glories nation as ours. 

 

The problem with ethanol as fuel is all the crunchies will try to drink it :P 

 

on a serious note, diesel has a higher energy density per volume than most fuels that have ethanol in them (from pure ethanol to E10 gasohol). 

 

Anyway, I was messing around with numbers and if I change: 

 

piston diameter = 120mm 

Stroke = 125mm 

18 cylinders (3 banks of 6) 

39 kW/L 

 

i would have an engine outputting ~1950kW (2600hp), but still be surprisingly compact. 

 

For reference, I could simply stack 3 Jumo 205s on top of each other and place them in the front section of my vehicle, and still have enough room for a transmission/drives and some random air/fuel ducts (though cooling the middle engine would be hard). 

Link to post
Share on other sites
  • Replies 542
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Restricted: for Operating Thetan Eyes Only By order of Her Gracious and Serene Majesty Queen Diane Feinstein the VIII The Dianetic People’s Republic of California Anno Domini 2250

Comrades! The time of your waiting is over! I introduce to you the Sierra Nevada VagonZavod AFV-50 Gun Tank   Frontal Dimensions Frontal Armor Turret Cheek Armor Array (n

Report from Lt. Col. [REDACTED] People's Auditory Forces Directorate of Political-Moral Reliability, Auditory and Political Officer for SNVZ and Military-Industry Liaison Officer for RFP "New Battle T

5 minutes ago, Lord_James said:

The problem with ethanol as fuel is all the crunchies will try to drink it :P 

Add a bit of methanol, and they will learn quickly.

 

5 minutes ago, Lord_James said:

On a serious note, diesel has a higher energy density per volume than most fuels that have ethanol in them (from pure ethanol to E10 gasohol). 

While true, it does not translate into engine power. Look at every hypercar, they run on gasoline, and in some cases E85. 

 

5 minutes ago, Lord_James said:

Anyway, I was messing around with numbers and if I change: 

 

piston diameter = 120mm 

Stroke = 125mm 

18 cylinders (3 banks of 6) 

39 kW/L 

 

i would have an engine outputting ~1950kW (2600hp), but still be surprisingly compact. 

 

For reference, I could simply stack 3 Jumo 205s on top of each other and place them in the front section of my vehicle, and still have enough room for a transmission/drives and some random air/fuel ducts (though cooling the middle engine would be hard). 

I am most concerned about the intake and exhaust, cooling should be a non issue if it is watercooled. 

Link to post
Share on other sites
4 minutes ago, Xoon said:

Add a bit of methanol, and they will learn quickly.

 

That’s just flavor :D 

 

4 minutes ago, Xoon said:

 

While true, it does not translate into engine power. Look at every hypercar, they run on gasoline, and in some cases E85. 

 

I think initial torque is a more valuable thing to have when you’re 10+ tons; those super cars might have some awesome speed, but they also weight like 200kg or something silly. Diesel provides that high starting torque to get moving, which is also why (when not using a turbojet) many MBTs use Diesel engines (I think). 

 

18 minutes ago, Xoon said:

 

I am most concerned about the intake and exhaust, cooling should be a non issue if it is watercooled. 

 

Oh, my intake and exhaust are going to be through the sponsons (intake on the starboard, exhaust on the port). 

 

For cooling, I was thinking of oil cooling, with an optional water/methanol system. 

 

 

Anyway, I’ve found some funny engine designs, like axial internal combustion, wankel, and opposed piston, opposed cylinder. I’m really tempted to use a wankel or an opposed piston axial engine because I like exotic, niche designs. 

Link to post
Share on other sites
2 minutes ago, Lord_James said:

I think initial torque is a more valuable thing to have when you’re 10+ tons; those super cars might have some awesome speed, but they also weight like 200kg or something silly. Diesel provides that high starting torque to get moving, which is also why (when not using a turbojet) many MBTs use Diesel engines (I think). 

Not really, you can make gasoline engines with high start torque too. To main reason diesel is used by the military is fuel efficiency. 

The issue with having a good torque curve on a gasoline car usually gives it horrible fuel economy. 

 

 

2 minutes ago, Lord_James said:

 

 

Oh, my intake and exhaust are going to be through the sponsons (intake on the starboard, exhaust on the port). 

 

For cooling, I was thinking of oil cooling, with an optional water/methanol system. 

 

 

Anyway, I’ve found some funny engine designs, like axial internal combustion, wankel, and opposed piston, opposed cylinder. I’m really tempted to use a wankel or an opposed piston axial engine because I like exotic, niche designs. 

Just remember to factor in how huge exhaust can get. Especially turbo exhausts. 

 

And I am all for special engines. 

Link to post
Share on other sites

Well, the D18-120 fits pretty well in the front of my tank: 

 

Spoiler

GgoImQO.png

BIryeuH.png

Ds4q7uV.png

BJ2ghgx.png

IuAnyfL.png

 

location is only preliminary, I'll optimize it better, later. 

 

Also, here's the new turret: 

 

Spoiler

ff1xTrY.png

 

yes, I know the mantlet is going to be big, but that's a given with a 6" gun. 

 

 

 

Completely off topic: 

Spoiler

how do I get the gif in my signature to play, like Jeeps and Loser? 

 

Link to post
Share on other sites
20 hours ago, Xoon said:

but can do do something like 25mm Alu + 50mm air + 20mm Alu?

Yes.

 

18 hours ago, Lord_James said:

Edit: Can we use the Napier Deltic (or similar) for our vehicles? 

 

Also, can I use polyurethane for insulation? Or are we limited to Urea-formaldehyde and asbestos? 

Sure.

 

18 hours ago, Lord_James said:

1700hp

Sounds fairly optimistic for the size of that engine.

 

15 hours ago, Xoon said:

One thing I have been curious about, is if it is possible to make a X opposed piston, were the piston heads have a wedge shape, and four cylinders meet in the center.

Its possible but doesnt really do much. The Germans experimented with 3-piston OPEs in the 30s.

Link to post
Share on other sites

Reduced front armour weight to 2.9 tonne per m2 with fuel.  And 2.5 tonne per m2 without fuel.  Defeats 360/960 CE, but only defeats about 800mm KE (depending on fuel).

 

Glacis top protection is still crazy high, but thats inevitable with ricochet angle plate sheathed with reactive armour.

 

 

Link to post
Share on other sites

Mg Hull casting including glass inserts and 25mm textolite liner. 12.7 tonne

 

Armour packages 11 tonne

 

Frontal arc 60/160 resistant

Side 50/150 resistant. Limited 60/160 area

 

Turret incomplete

 Roof nera/era still to optimise

 

Link to post
Share on other sites

Alright, so, the D18 engine (and its transmission / intakes / exhaust), I’m theorizing as such: 

 

the D18 itself is a 2-stroke, 18 cylinder, opposed piston, uniflow scavenging, turbosupercharged, turbo-compound, mixed cooling, diesel engine limited to 1850 rpm per shaft, and 2000hp; this should give a hp/t of 23.5 for an 85 tonne vehicle, and  22.2hp/t for a 90 tonne vehicle, which is pretty good if I do say so myself. 

 

The engine is placed in a similar location as my first picture (underneath the hump), with the turbo and super chargers above it, the transmission in the V shaped area between the lower and upper armor cavities, with other systems placed where I can fit them. 

 

 

The chargers are fed from intakes on the starboard sponson (and possibly the section of roof forward of the front propellant rack). These provide the air for ignition as well as cooling; cooling air ducts run along the piston tracks, both inside and outside, while ignition air ducts input from the outside of the engine. Ignition ducts may have a water/methanol system connected to them. Ignition air ducts also run through the liquid cooling system, functioning as a radiator and pre-warming the air. 

 

The liquid cooling system is a basic type using a water/glycol, water/betaine, castor oil based fluids, or other similar mixtures (just water if an emergency), with a pump circulating fluid from around the ignition air ducts, along the combustion chambers of the engine (both inside and out), and back to the ducts. 

 

Fuel is pumped from the tanks in the sponsons, underneath the crew compartment, and in 3 (or 4) forward fuel tanks and input through the middle of the engine. Fuel is typically 40-45 cetane diesel or bio-diesel. 

 

Exhaust is released from ducts on the outside of the engine, each with an expansion chamber for better fuel economy. 6 exhaust ducts (one row of pistons) merge into a single duct, where they pass through small power recovery turbines, (a la R-3350) each recovering 50-60hp, and connect to the turbocharger, the vehicle’s general electrical system and batteries, and a hydraulic assist on the crankshaft, separately. Afterwards, 2 ducts are taken through the bottom of the tank, through lightly armored pipes parallel to the tracks, and outputting along the rear 1/4 of the suspension, perpendicular and positively inclined to the tracks (so not to kick up excessive dust). The third exhaust is ducted into the port sponson, and exhausts horizontally, and to the rear, between the driver and the turret ring. 

 

The transmission is a semi-automatic, continuously variable transmission with “5 forward and 3 reverse” gears. By this, I mean the driver manually puts the transmission into a gear, but the transmission itself has different gears which switch automatically, to smooth out acceleration and power to the sprocket*. The first 2 forward and reverse gears are low speed, high torque gears, and the final 3 forward and last reverse are for higher speed. 

 

 

*There are 2 sets of gears: one set the driver controls, and the other is automatic via the transmission. The driver has his 8 manual, main gears, and the transmission has 10 automatic, intermediate gears. 

 

The driver inputs a gear, and the transmission automatically applies it’s gears in sequence. It looks like this, for speeding up: 

F1-1 

F1-2 

F1-3 

... 

F2-1 

F2-2 

F2-3 

... 

and so on. The transmission always reverts to its first gear when the driver switches his gear, and gears are ratio-ed so that the [X]-10 gear is similar to (but not the same as) the [X+1]-1 gear. This is to minimize lurching, making the ride smoother for the crew. 

 

 

There is also a 80hp 2-stroke, 1 cylinder opposed piston diesel APU mounted in the starboard sponson midway between the propellant rack and turret ring, which powers the electrical system when the D18 is off. 

 

 

Im also looking into OPOC, OP V, and a Wankel engine, but for now, it’s the OP Delta. 

Link to post
Share on other sites
2 hours ago, Lord_James said:

Exhaust is released from ducts on the outside of the engine, each with an expansion chamber for better fuel economy. 6 exhaust ducts (one row of pistons) merge into a single duct, where they pass through small power recovery turbines, (a la R-3350) each recovering 50-60hp, and connect to the turbocharger, the vehicle’s general electrical system and batteries, and a hydraulic assist on the crankshaft, separately. Afterwards, 2 ducts are taken through the bottom of the tank, through lightly armored pipes parallel to the tracks, and outputting along the rear 1/4 of the suspension, perpendicular and positively inclined to the tracks (so not to kick up excessive dust). The third exhaust is ducted into the port sponson, and exhausts horizontally, and to the rear, between the driver and the turret ring. 

Are you sure you can use compound turbo and a ordinary turbo? Wont the compound turbo rob the exhaust of all its energy? 

Also, will the engine run at a constant rpm? If not, I am not sure if a compound turbo would be worth it. 

If you want the maximum out of the turbo, you can use a 3 stage turbo setup, and small, medium and large turbo to cover the entire range and pressure.  I don't remember if variable geometry turbos are invented yet. 

Also, is the vehicles auxiliary power, powered by the exhaust? 

 

 

2 hours ago, Lord_James said:

The transmission is a semi-automatic, continuously variable transmission with “5 forward and 3 reverse” gears. By this, I mean the driver manually puts the transmission into a gear, but the transmission itself has different gears which switch automatically, to smooth out acceleration and power to the sprocket*. The first 2 forward and reverse gears are low speed, high torque gears, and the final 3 forward and last reverse are for higher speed. 

Why do the driver need theses gears? 

Also, if you want better economy, why not simply have a economy and power option for the driver. 

 

9 hours ago, Kal said:

Mg Hull casting including glass inserts and 25mm textolite liner. 12.7 tonne

 

Armour packages 11 tonne

 

Frontal arc 60/160 resistant

Side 50/150 resistant. Limited 60/160 area

 

Turret incomplete

 Roof nera/era still to optimise

 

How weld-able is this magnesium alloy? 

Link to post
Share on other sites

Magnesium alloy is generally better for welding than aluminium.

 

But 

 

Aluminium makes better sheet and plate than Magnesium.

 

But 

 

Magnesium makes better castings than Aluminum.

 

So while Magnesium is better for welding than Aluminum, much less welding is used with Magnesium because its generally a casting anyway.

 

Magnesium is sweet for castings, but its just not worth it for sheet or plate work. 

 

The alloy i would suggest is ZE41, popular from late 1940s to late 1960s.

https://www.slideshare.net/mobile/GkhanBier/mg-alloys-in-industry

Edited by Kal
Link to post
Share on other sites
2 hours ago, Xoon said:

Are you sure you can use compound turbo and a ordinary turbo? Wont the compound turbo rob the exhaust of all its energy? 

 

Pretty sure, the super charger is run via a mechanical system, and the turbocharger is powered by one of the turbo scavengers. 

 

2 hours ago, Xoon said:

 

Also, will the engine run at a constant rpm? If not, I am not sure if a compound turbo would be worth it. 

If you want the maximum out of the turbo, you can use a 3 stage turbo setup, and small, medium and large turbo to cover the entire range and pressure.  

 

Not quite, but it’s not suppose to vary past 1600-1850 rpm. 

 

3 hours ago, Xoon said:

 

Why do the driver need theses gears? 

Also, if you want better economy, why not simply have a economy and power option for the driver. 

 

More precise control? Idk

Link to post
Share on other sites

BMP 3

30mm 2a72 has ke about 180,000j, exit velocity about 960-1120m/s

100mm 2a70 has ke about. 480,000 to 840,000j, exit velocity 250-350m/s

 

Resolve for different durations, turns out that the 30mm and 100mm have same force on vehicle structure, but the 100mm has a longer duration.

 

Hmmmm

 

Link to post
Share on other sites

So if proposed tank uses russian 57mm autocannon, ke is 1,425,000j, exit velocity 1000m/a

 

To balance force on vehicle allows HEAT

91mm At 940m/s

105 mm at 760m/s

125 mm at 660m/s

160 mm at 500m/s

 

Seeing how easy it is to defeat smaller HEAT warheads, the complementary cannon is either the 160 mm at 500m/s. (Is is similar ratio to BMP 3 guns)  or just go with the 90mm and make that an auto cannon also.

Link to post
Share on other sites
18 hours ago, Kal said:

Magnesium alloy is generally better for welding than aluminium.

Interesting, I always thought magnesium was very hard to weld.  I guess it stems from the fear of the entire work piece catching fire, even if it is very unlikely. 

 

 

15 hours ago, Lord_James said:

Pretty sure, the super charger is run via a mechanical system, and the turbocharger is powered by one of the turbo scavengers. 

Do you use the supercharger as a blower or for better torque and low end RPM? 

 

For the compound turbo, is it something like this:
800px-NomadSchematic_185kBpng360kB.png

 

I suppose that you could have a compound turbo sized so that it spools up at a large way of the rev range. 

For example. Lets say the tank spends most of its time between 800-1400 RPM, then it would be able to produce enough exhaust gas to power the turbine at roughly 8-900 RPM, and for the higher rev range rarely used, a turbocharger would be employed? 

 

So, if I understand the engine correctly, at low RPM, the supercharger would be used to provide power and compression instead of using the crank to compression.  At medium RPM the recovery turbine would have been spooled up to max, and at higher RPM the supercharger would be decoupled by a magnetic clutch or similar and the turbocharger would kick in. 

 

Am I correct? or am I completely off?  

 

Also, are gas turbine turbochargers allowed, @N-L-M

 

Quote

Not quite, but it’s not suppose to vary past 1600-1850 rpm. 

 

 

More precise control? Idk

Well, the thing is, a CVT, is a continuously variable transmission, meaning infinite gears in theory. 

Which means you can have a gearbox with a ratio of 1 to 20, with anything in between. Like 15, 12, 7, 2, 10,12312321 etc. 

 

This means that the engine will always have the appropriate gear ratio for the RPM. No gear selection, just the engine humming happily at its optimal RPM. 

You can, however have a selector for economy and power. 

 

Lets say the engine produces its max power at 3000RPM, but runs the most efficient at 2000RPM, then the transmission would aim to always have the engine at 2000RPM for economy, or 3000 RPm for max power. 

You should have a "first gear" and reverse gear though, as a conventional CVT provides poor torque initially,  and is incapable of switching direction. 

 

It would have 3 gears, first gear, continuous gear and reverse. 

 

 

Love your engine so far btw, certainly a neglected design in the automotive world. 

Link to post
Share on other sites
3 hours ago, Xoon said:

Also, are gas turbine turbochargers allowed

Sure, but complex engine designs like these are bound to lead to trouble. In particular, trying to squeeze significantly more power per dispacement than the Kharkovite engine is not going to make you a happy camper.

Link to post
Share on other sites

Re Mg vs Al for welding.

 

The Mg is easier for fine welding like bikes and lightweight structures, but is unsuitable for thick welds.  Mg welding uses only about 40% of the heat for the same thickness as. Al welding but is unsuitable for deep penetrating welds because the Mg boiling point is a lot lower than Al boiling point.  (Even though the melting points are almost the same.)

 

Al obviously conducts heat away from the weld a lot faster than Mg.

Link to post
Share on other sites
1 hour ago, N-L-M said:

Sure, but complex engine designs like these are bound to lead to trouble. In particular, trying to squeeze significantly more power per dispacement than the Kharkovite engine is not going to make you a happy camper.

Pfft, of course not, who would want to squeeze more power out of  it? he he

 

* discreetly crumples paper and throws in trash*

Link to post
Share on other sites
  • N-L-M unfeatured this topic

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Content

    • By Beer
      I haven't found an appropriate thread where to put some interesting rare stuff related to WW2 development, be it industrial one or makeshift field modifications. 
       
      Let's start with two things. The first one is a relatively recently found rarity from Swedish archives - a drawing of ČKD/BMM V8H-Sv tank. The drawing and a letter was found by WoT enthusiasts in Swedish archives in 2014 (the original announcement and the drawing source is here). The drawing is from a message dated 8th September 1941. One of the reasons why this drawing was not known before may be that the Czech archives were partially destroyed by floods in 2002. Anyway it is an export modification of the V-8-H tank accepted into Czechoslovak service as ST vz.39 but never produced due to the cancelation of all orders after Münich 1938 (for the same reason negotiations about licence production in Britain failed). Also later attempt to sell the tank to Romania failed due to BMM being fully busy with Wehrmacht priority orders. The negotiations with Sweden about licence production of V8H-Sv lasted till 1942, at least in May 1942 Swedish commission was present in Prague for negotiations. The tank differed compared to the base ST vz.39 in thicker armor with different front hull shape (armor 60 mm @ 30° on the hull front and also 60 mm on the turret; all sides were 40 mm thick). The tank was heavier (20 tons) and had the LT vz.38 style suspension with probably even larger wheels. The engine was still the same Praga NR V8 (240-250 Hp per source). The armament was unchanged with 47 mm Škoda A11 gun and two vz.37 HMG. The commander's cupola was of the simple small rotating type similar to those used on AH-IV-Sv tankettes. It is known that the Swedes officially asked to arm the tank with 75 mm gun, replace the engine with Volvo V12 and adding third HMG to the back of the turret. In the end the Swedes decided to prefer their own Strv/m42. 

      Source of the drawing
       
      The second is makeshift field modification found on Balkans. It appears Ustasha forces (and possibly some SS anti-partizan units) used several Italian M15/42 medium tanks with turrets from Pz.38(t). There are several photos of such hybrids but little more is known. On one photo it is possible to see Ustasha registration number U.O. 139.

      Few more photos of such hybrid.
       
      It appears that the source of all those photos to be found on the internet is this book, Armoured units of the Axis forces in southeastern Europe in WW2 by Dinko Predoevic. 
       
    • By SuperComrade
      I was recently looking at the Japanese wikipedia page for the Chi-Ha tank, and it had this section on the name of the tank:

       
       
      I have never heard of such nomenclature, and obviously I don't have access to such documents since I don't live in Japan. There is no reference for this part, so can anyone confirm that they actually did use "MTK" etc.?
    • By Monochromelody
      70 years ago, January the 2nd, 1951. To the North of Seoul, in the mountains and hills near Go-yang-tong(高阳洞), British 1RUR dug in and fought against advancing PVA forces. 1RUR got a task force called Cooperforce to support, this is a tank unit from Royal Tank Regiment and Royal Artillery, equipped with Cromwell tanks. 
      When Matthrew Ridgeway assigned the order of withdraw in this afternoon, the US force covering British force's left flank quickly escaped from their sector, leaving the British were completed unawared and uncovered. 
      When the night falls, was cold and dark in the valley. 1RUR had to withdraw in the darkness. All of a sudden, a US spotter aircraft flew over the valley, drop some illumination flares upon the retreating convoy. 
      Fierce battle broke out when flares fall down, PVA firing from all directions, the cold valley became deadly kill zone. Some PVA soldiers put away their rifles, assaulting with hand grenades, satchel charges and Bangalore torpedoes. They even set up mortars on the hill, laying shells with direct fire. 
      200 British soldiers and artillerymen were killed or captured in one night. 1RUR's Battalion Commander Tony Blake was believed KIA. Cooperforce was completely knocked out, all 12 tanks were destroyed or captured by light infantry. Leader Ashley Cooper were also killed. 


    • By Toxn
      This is the competition entry thread.
       
      Please submit your complete entries here (all entries will be judged complete when judging begins in the first week of November) and keep the other competition thread for discussion and chatter.
       
      Once judging is complete I will make a post here to discuss the entries and announce a winner.
       
      Best of luck!
       
      Update: final submissions should be in hand by the 22nd of November 2020.

×
×
  • Create New...