Wankel engine in a tank?

I was thinking, since I get my drivers liscence soon about what car I would buy. I saw one with a Wankel engine, and had no idea what it was. So I researched it a bit and saw the benefits and cons. And than it hit me: Why not put one in a tank?

The benefit of having a wankel in a tank would be simple. Similar power, for much less weight and space. But it would sacrifice fuel efficiency unless they REALLY got it right.

-For the same size engine, much more horsepower.
-For similar powered engine, more space for ammunition or other necessities.
-Dip in fuel efficiency

Now I feel that it is important to give you an idea of just how much more powerful a wankel engine is:

In the car I am considering, a tiny, 1.3L wankel puts out a SCREAMING 232 horses. Try that with a 1.3L piston engine. Now, imaging that...but UPSCALE IT BY A FACTOR OF 10!

Would this be practical for a tank? There are some great videos about how a wankel engine operates on youtube, just look it up.

Mazda has been successfully refining this engine for years with it's RX line here in the states. I believe they used to use it in early pick-up trucks. Not sure how widely they implement it overseas. I agree with you though, alot of output from such a small form-factor. And there're are like what, 3 moving parts in the engine?!

It would be interestign to see how it scales up as you suggest.



[edit on 31-5-2007 by Stale Cracker]

yeah, my rx-7 had a rotary engine in it, im sure the troops will love the frequent trips to the mechanic. that thing broke about ever third tuesday. the rotary engine is getting better, but it still has a way to go to be as reliable as a normal combustion engine. the problem is even a small unbalance on the rotor will cause the engine not to run, build tolerances must be very very small and a grain of sand will destroy it. its not really the motor you want to be humping around the desert.

[edit on 5/31/2007 by bokinsmowl]

Upscaling would be problematic. The apex seals do not "scale" very well, neither do the combustion "chambers" owing to a very open flame propagation front that can lead to pre-ignition on a low-lead gasoline motor... that's one reason why Mazda went from 2 rotor, to 3 and now 4. The RX-8 is doing well in the roadraces this year, nice exhaust note too - Wankel's are loud.

But it might just make a sweet mill for a super-legere wheeled urban warfare vehicle... torque's the "thing" for haulin' mass - ask any trucker. Zoom, zoom, zoom and the Mazda go "Hummm".

I rode a Suzuki RE-5 as a "driver" back in the '70's... very, very impressive acceleration to 70MPH... "King of 5th gear roll-on" but nothing on the big-end.

Cheers,

Vic

There´s not only the problem that it does not suffice to "supersize" the current engines; a wholly diferent issue are the constructional needs of a Diesel engine. You´d have to strengthen the engine walls and working parts so much that you wouldnt have THAT much of a weight advantage; but still the problem of the higher fuel consumption.

Needless to say, there are zero families of developed and thoroughly tested big Diesel-Wankel engines, which would pose a high risk for anyone willing to finance such a development.

Its also not really necessary, there is enough potential in piston Diesels. Just as an example, the Leopard 2 Tank uses a the very acclaimed MTU 873 engine. Nowadays, MTU markets the 883 as a replacement and part of the so-called "Europowerpack". That engine is a full 1/4 smaller and subsequently lighter than the 873, while being (ungoverned) capable of putting out more power (up to 2016 kW) and consumes less fuel.

[edit on 1/6/2007 by Lonestar24]

Reason why a wankel engine wouldn't work in a heavy vehicle is a wankel engine doesn't have enough torque,would take forever to get it going,why they use diesel motors they develop torque at lower RPM's

While its true that wankel engines have low torque at low speed, they have smooth, straight, in-line RPM climbes and they DEFINATELY make up for their low torque at high speed, when you get way more oomph.

Wankel engines have essentially 3 moving parts making them more reliable.

Wankel engines can be adapted to run on any burning fluid without much modification.

I dont see why not

As Mazda is leading in the field of Wankel engines these days and Japan is developing a new tank, we might see a wankel engine powered tank quite soon. Also consider that Wankel engines also work using Hydrogen.

Originally posted by BlackWidow23
While its true that wankel engines have low torque at low speed, they have smooth, straight, in-line RPM climbes and they DEFINATELY make up for their low torque at high speed, when you get way more oomph.

Wankel engines have essentially 3 moving parts making them more reliable.

Wankel engines can be adapted to run on any burning fluid without much modification.

I dont see why not

Not really, the higher the RPM, the less the Torque. You want less RPM to get the most Torque, if the engine doesn't develop most of its torque at low speeds you might have a bit of a problem with getting up to speed while tugging a large load.

Shattered OUT...

That can be solved with an engine design that has more than 2 rotors, like a 4 rotor, plus if you want to take it further, give it a big turbocharger with a massive boost.

Originally posted by BlackWidow23
While its true that wankel engines have low torque at low speed, they have smooth, straight, in-line RPM climbes and they DEFINATELY make up for their low torque at high speed, when you get way more oomph.

Wankel engines have essentially 3 moving parts making them more reliable.

Wankel engines can be adapted to run on any burning fluid without much modification.

I dont see why not

Yes, but the problem is getting a 50+ ton tank moving, it's not a 2500lb RX7! High speed isn't that important in a tank, and useless if it takes forever to get there.


Apex seals are prone to fail! (guess you haven't owned one yet?) especially with forced induction! which is the only way it could even be possible to power a tank.

Turbines have few moving parts, and can run on a variety of fuel.

IIRC Mazda did produce a rotary used in buses which was a 4 rotor, but again a tank is much much heavier than a bus. To my knowledge they arent used anymore in buses and that probably didn't work out for a reason.

Rotary's are better suited for light aircraft applications, and sports/race cars. AFAIK the only japanese car to win Le Mans was Mazda's 787 which is powered by the 4 rotor 26b



[edit on 6-6-2007 by warpboost]

A boxer type engine would be much more suited for tank as they have a low profile and it might help you get more usefull space into the hull. And i assume a boxer-diesel (especially with forced induction) might be able to put out the torque needed to move an MBT.

I'm pretty sure there have been some tanks with horizontally opposed 12 cylinders in them.

I found this on wikipedia, but it says horizontally opposed V-12 It can only be one or the other

en.wikipedia.org...

Originally posted by warpboost
I found this on wikipedia, but it says horizontally opposed V-12

It can only be one or the other ....

Nope, the angle of a V-engine is more or less irrelevant; can be anything from 1° (which wouldnt make much sense) to 180° degrees. What (usually) makes it a V-engine is its use of a single crankshaft as opposed to an inline engine that has one crankshaft per cylinder bank. A Boxer engine uses a single crankshaft as well, but it HAS to have 180° opposed cylinders because each two opposing cylinders fire at the same time, the V-engine fires in a sequence similar to an in line engine.

These two countering cylinders then effectively negate much of each others vibrations. Ferrari for example sometimes used flat V12s, but improperly called them Boxer engines.

[edit on 7/6/2007 by Lonestar24]

slightly drifting off topic :

" vee engines " whatever the angle between cylinder banks have 2 [ TWO ] connecting rods [ 1 from each bank ] attached to the same crank journal

in a " typical vee 6 " layout you have something like this :

. 1 2 3

. 4 5 6

with only 3 jounnals and 4 bearings

and piston pair 1&4 , 2&5 and 3&6 con-rods share a single journal

the big end bearings have individual thrust washers to counteract endfloat and interference

" boxer engines " have one con-rod / journal and must have 180 degrees between banks

if you built a " boxer " with less than 180 degree bank - it would ` jump ` or attempt to .



[edit on 8-6-2007 by ignorant_ape]

I hunted around a bit and found out that the boxer patent is held by Karl Benz 1896... true boxers are 1 con rod per journal with 180 degree opposed paired cylinders... the Ferrari F1 motor mentioned is a "flat" that is, zero degree bank angle opposed 12 cylinder with 2 rods per crank journal. The media called it a "boxer" and it stuck. The same was true of the early Matra F1.

Ah, the Wankel-Tankle is a model kit! The wheeled concept model employs a larger than 1.3L (LOL) 4 rotor wankel based in fantasy with 2000 claimed conceptual ponies, perhaps unicorns? It's more like the super-leggere urban assault vehicle I thought might be appropriate in an earlier post. Wanna see? Here's a link.

The M1A1 Abrams is 70 tons. It uses a Textron Lycoming AGT 1500 Turboshaft - Power Rating: 1,500 BHP at 3,000 RPM Peak Torque Rating: 3950 lb/ft @ 1,000 rpm (now that torque). It has an Allison auto-shift 4 forward 2 reverse cross-shaft planet cluster and some wild hydralics for drive and steering.

The M-47 Patton Tank is 50 tons with an aluminum air-cooled 1792-cubic-inch V-12 with 810 horsepower and 1590 pound-feet of torque, many were converted to diesel owing to gasoline being "not-so-good" around explosives!

Some Merkava (apparently before the "4") has a hot rod Detriot Diesel turbo than I believe is a V-12 and puts out 1500 HP and quite likely near 2800 lb/ft. of torque.

If you had a really, really, really big tank in mind then there's mother-of-all diesel's, Wartzilla scroll down for the photos... it's worth it. How about a 300 ton crank shaft?

Cheers,

Vic

EDIT: To agree with the following poster.

[edit on 10-6-2007 by V Kaminski]

Originally posted by V Kaminski

The Merkava 4 has a hot rod Detriot Diesel turbo than I believe is a V-12 and puts out 1500 HP and quite likely near 2800 lb/ft. of torque. ...

Minor correction: The Merkava 4 is powered by the same german MTU 883 engine I mentioned earlier. Detroit Diesel isn´t capable of building such an engine. Due to special export law peculiarities, the engine is sent to the USA in components and then gets assembled by General Dynamics Land Systems as the GD883.

I stand corrected Lonestar and have appended and edited my previous post to reflect this corrected data. Thank you.

Was the Mk 4 prototype equipped the Detriot Diesel early on? No matter. Here's a link where folks can confirm Lonestar's correction on the type of motive power in a Merkava MK 4.

Cheers,

Vic

Its been mentioned a few times, but ill say it again. Torque is the issue. Arguing that raising the RPM and therefore Kilowatts negates relying or torque is only perhaps viable when powering gernerators for electric traction motors.
Rotary engines main draw back, as has been mentioned is its tendency to waste fuel. Raising the RPM to generate the required KW's (HP) would further the negative fuel consumption. A good, reliable, long stroke multiple cylinder piston engine give good torque, at low, fuel effecient rpms.
An example of a high reving, fuel guzzling tank is the M1A1. It uses gas turbines, and drinks truck loads of fuel to move anywhere. But the upside is loads of power, despite needing a support/refuel network that features as many as 2 or 3 trucks per tank.

how bout a hybrid rotary tank? electric armatures make tons of torque, and the rotary can take over after the electric motor gets the tank going? seems kinda pointless but if you really want a "wankel tankel", this might work.