Zongshen cd 100 /912 clone

[facthunter]

Formidible thing . Mild resemblance to a Napier  Lion on steroids.  Nev

[turboplanner]

1 hour ago, Area-51 said:

 

😀😀👏👏👏

Zveda M503 42 cylinder Radial

 

https://www.google.com/search?q=dragon+fire+tractor&rlz=1C1FGUR_enAU949AU949&oq=Dragon+Fire+tractor&aqs=chrome.0.0i512l2j0i22i30j0i390i650l4.121923402j0j15&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:40d1819e,vid:if7d14JJEfM

[facthunter]

Obviously I only saw 1/2 of it. Boys & their toys.  Nev

[onetrack]

It's a Zvezda, not Zevda ... a 42 cyl diesel radial, 6 rows of 7 cylinders, rated at up 4,000HP. The Rooskies used 3 of them for powering their high speed attack missile patrol boats.

There were a range of these engines built from just after the end of WW2, and the Rooskies actually went up to 56 cylinders at one stage.

 

Despite facthunters pet hate, the Zvezda engines had built up crankshafts, comprised of multiple sections pressed together!

 

The Dragon Fire tractor has had the engine converted to spark ignition with new cylinder heads, runs on methanol, and can produce up to 10,000HP in short bursts, but is generally throttled back to 8,000HP.

 

I don't know what kind of aircraft the Rooskies intended to power with an engine that weighs over 5 tonnes, but it must have been some aircraft!

 

https://oldmachinepress.com/2016/09/05/yakovlev-m-501-and-zvezda-m503-and-m504-diesel-engines/

 

Edited July 14, 2023 by onetrack

[facthunter]

Most long radials are a disaster. for reliability. Crankshaft is their weak spot. They'd have a heap of Prohibited RPM's to avoid because of the rotating masses .  Stick to single row if you can for small stuff. Some of the couplings are pinch bolts and radials can have dynamic counterweight Damping. That is why a lot of them make horrible mechanical noises when starting or idling slowly. Nev

[Area-51]

3 hours ago, facthunter said:

Most long radials are a disaster. for reliability. Crankshaft is their weak spot. They'd have a heap of Prohibited RPM's to avoid because of the rotating masses .  Stick to single row if you can for small stuff. Some of the couplings are pinch bolts and radials can have dynamic counterweight Damping. That is why a lot of them make horrible mechanical noises when starting or idling slowly. Nev

Bose A20; everything sounds awesome! 😀

[aro]

On 13/07/2023 at 10:17 AM, facthunter said:

 Why is having a prop bolted on the end of the crank a TERRIBLE idea? There's NOTHING simpler. The prop acts as a flywheel  and if you gear a flywheel you're looking for trouble. Flat motors have the shortest cranks of all (bar radials).

The biggest problem is you have to run the prop and engine at the same speed. To fast for a prop (even if you like the sound of the tips approaching the sound barrier it's not efficient) and slower than ideal for an engine. So the engine has to be bigger to run at that slow speed, and therefore heavier. Attempts to save weight can compromise reliability.

 

Another problem is that the crankshaft is susceptible to damage with the propeller bolted directly to the end. Have a look at Lycoming's guidance for when a tear-down is required. Any damage requiring repair of the propeller, whether the engine was running or not...

 

Yes, the propeller acts as a flywheel, but it's a very springy flywheel and springy flywheels are probably not ideal either. With the propeller bolted rigidly to the crankcase the whole system is a spring, from the tips of the propeller through to the other end of the crankshaft. The engine designer has to consider the vibration, but can't know the exact characteristics of all propellers that might be used.

 

I think the important length measurement for a crankshaft is the zig-zag length through all journals - not just a straight line from front to back of the engine. I'm not sure how a flat motor crankshaft compares to others, but the 2 pistons at 180 degrees looks like it creates a very long section of crankshaft between main journals - especially in an engine with a long stroke.

 

Simple? Definitely. Good? I'm not so sure. It looks more like it's cheap and adequate rather than good.

 

Even when these engines were designed they knew how to build better.

[spacesailor]

I've just looked at my daughters 2019 Mazda3 !.

Four cylinders, but two cut out when in ' cruise ' mode, it also stops the engine at lights , when the brake pedal is pressed hard . Great for highway And town driving. 

spacesailor

[facthunter]

.ARO Reduction gears are a problem  when the flywheel is driven through them.  It would never be doneona  car or motorbike.  That's why the best are Sun and planetary. Lycomings six has a dynamic torsion balancer on the opposite end to the flywheel.  A straight four and flat four crank has similar shape. More main bearings often means more effective length. ALL fours have the pistons stopping at the same time twice per revolution and the pistons have a flywheel effect also. Sixes are noticeably smoother when you have one up  front. Nev

[skippydiesel]

41 minutes ago, spacesailor said:

I've just looked at my daughters 2019 Mazda3 !.

Four cylinders, but two cut out when in ' cruise ' mode, it also stops the engine at lights , when the brake pedal is pressed hard . Great for highway And town driving. 

spacesailor

I just cant see how these overly complicated (cylinder shut down) stop / start engines can possibly have any longevity. I was brought up to operate (all engines) with consideration when cold/warming up and cooling down/before shut down. These stop/start engines must require extra battery power, more robust starting systems and have difficulty in getting/keeping to/ a sustained operating temperature. Add all this to their target  environment - city driving - and I would suggest a recipe for problems.

[kgwilson]

I've never understood the logic of this stop start process either. A friens has a Subaru XV with the same feature & he hated it so has it permanantly disabled. In heavy city reaffic this happens all the time. On a hot day this means the air conditioning compressor is shutting down and restarting all the time too. This situation is where an electric vehicle shines.

[facthunter]

They've been around for years now and don't seem to be a problem. Things must be designed for what  they do. By the time you've lifted your foot from the brake, its running.  Nev

[facthunter]

It's designed for Europe and dense traffic.  A steam engine would be stopped the same as an electric one.. Nev

[kgwilson]

You still have to keep the steam pressure up so even stopped it would be using fuel to maintain steam pressure. An electric vehicle stopped uses virtually no energy.

[facthunter]

Steam uses much more when power is required and I'm  NOT recommending going to steam at all. I just don't see starting a  hot motor again after a minute or so  is any great deal.  Nev

[onetrack]

Starters are far cheaper in total costs overall, than idling fuel costs and pollution output. I often switch off my diesel Hilux when I can see a prolonged wait. In the U.S., many municipalities have specific bylaws banning idling for more than 3 minutes - to reduce pollution mostly.

I've seen the figure on the estimated level of fuel wastage caused by unnecessary engine idling - mostly trucks - and it's a staggering figure. Add in car idling fuel waste and the figure would probably double.

[facthunter]

There used to be a pattern of leaving diesels idling rather than shutting them down. Metering the very  small amounts used at idling is difficult and would not be the cleanest burning mode. Often you'll get white smoke when you throttle up after prolonged  idling. It could also contribute to bore glazing with carbon formation above the top ring.  Nev

[BrendAn]

5 hours ago, facthunter said:

.ARO Reduction gears are a problem  when the flywheel is driven through them.  It would never be doneona  car or motorbike.  That's why the best are Sun and planetary. Lycomings six has a dynamic torsion balancer on the opposite end to the flywheel.  A straight four and flat four crank has similar shape. More main bearings often means more effective length. ALL fours have the pistons stopping at the same time twice per revolution and the pistons have a flywheel effect also. Sixes are noticeably smoother when you have one up  front. Nev

You need to tell rotax they should not be using those long lasting reduction gears all Their aircraft engines have.

[IBob]

Meanwhile, in Thailand, despite the unavailability of Zvezda engines...........:

 

[turboplanner]

IBob, that flywheel shouldn't be on the engine give them a rattle at idle.

[BrendAn]

37 minutes ago, IBob said:

Meanwhile, in Thailand, despite the unavailability of Zvezda engines...........:

 

Looks like fun

 

[IBob]

Surely does, BrendAn..............the need for speed.................)

[spacesailor]

BUT

That Mazda motor doesn't stop when doing a gentle stop or if you use the handbrake 

At the lights. .

spacesailor

[skippydiesel]

6 hours ago, facthunter said:

They've been around for years now and don't seem to be a problem. Things must be designed for what  they do. By the time you've lifted your foot from the brake, its running.  Nev

 Its only the technology that's "been around for years", the vehicles don't seem to last that well at all or am I imagining that the roads are filled with newish looking vehicles these days?  So different from the 70's when the average age of a car was something like 10 + years.  The young people replace their vehicles within the warranty and or under 100,00km to get a good resale and never so much as lift the bonnet between shop servicing. Old "clunkers" and much loved "restorers" are infrequently seen these days.

[facthunter]

i worked associated with reconditioning for years and  the mileage the early stuff went before needing rebuilding was very low. A bout 45K miles for an Austin A 40 up to about 70K for a Valiant slant 245. The ERA had data on a whole range of vehicles and even got involved with Correcting some of the design Flaws many vehicles had. Plenty of cars are running 250K Kms + without any engine dismantling. By the time the motor's done the rest of the car is too but we are doing bigger PRIVATE annual distances than was common then. Cars are better and cheaper relative to wages etc., Volvo when they were (Boxy) had the highest recorded average life of 7 years. Now cars are accidented off the road as it's easy to be written off.  When out of warrantee the car becomes a liability for repairs that become a high % of their Value. so People seek good warrantee today which is far longer than the older car lasted  A 3 year old vehicle out of warrantee is really only worth about 1/2 the price of a new one in my view anyhow. Ther's a lot of risk buying older stuff say 10 years as it will usually need things like a head gasket and that's just the beginning of your troubles..Nev