Giant heavy flywheel for cheap?

[joeyg1973]

So I want to make an engine dyno because I am a sucker for stupid projects. One of the key ingredients is a flywheel that is heavy enough to make the engine work hard for about 20 seconds and be able to take up to about 10,000 rpm to be safe. It appears that I need something that weighs about 1000 lbs. Can anybody think of a cheap way to make something like this to meet the specs above?

There is this site that shows a big freaking wheel Steve's DIY Dyno - My Dyno Info
but in dyno terms it isn't really that big. Anyway I figure there has to be a creative way to do this cheap. I am contemplating maybe cement in a drum that I spin at say 500 rpm to balance it but this still scares the hell out of me because I can see this exploding at speed easily.

So I seek the wisdom of the group.

 

[GLTHFJ60]

I would never try to build something, like a flywheel, that weighs 1000lbs and expect it to hold up at 5000 rpm's. Good luck.

 

[joeyg1973]

Come on think of the fun one could have if it failed. Just need to aim it at that neighbors house that you can't stand and watch the carnage ensue as it rips through that house and several others for a few miles!

 

[GLTHFJ60]

Come on think of the fun one could have if it failed. Just need to aim it at that neighbors house that you can't stand and watch the carnage ensue as it rips through that house and several others for a few miles!

In jersey, I'm sure there are a couple of people you could find to test it out for you once you've built it.

 

[D'Animal]

How much does a wheel from a train weigh?

 

[beaufort-fj60]

depleted uranium is heavy, very heavy... look around you can buy the stuff.

Manufacturing Sciences Corp. - Oak Ridge, TN
Manufacturer, Custom Manufacturer
Company Profile: Manufacturer of flywheels made from depleted uranium for inertial & energy-storage devices.

http://www.thomasnet.com/heading.ht...4204&searchpos=7&cid=10024376&navsec=products

 

[joeyg1973]

How much does a wheel from a train weigh?

I thought about that and there is supposedly someone who has built a dyno using one, but even if I could get bullet train wheels I don't think that they would be capable of very high RPM.

 

[GLTHFJ60]

I thought about that and there is supposedly someone who has built a dyno using one, but even if I could get bullet train wheels I don't think that they would be capable of very high RPM.

Why not? Solid steel I would think is the best option. Balance it and you're good to go.

 

[joeyg1973]

OK look, I know that Jersey has the most superfund sites, but it isn't just what you see when you land in Newark. There really is a reason why it is called the Garden State. There is a whole lot of farms, parks, lakes, and forests that are not overgrown suburbia and are not polluted.

However I am curious about the depleted uranium. I am not sure if you are joking or not because I am pretty sure that depleted uranium is radioactive. I sure as heck don't want to end up looking like this:

http://http://www.darkgovernment.com/news/depleted-uranium-found-in-victims-of-gaza-offensive/depleted_uranium_effects4/

...no matter how much you guys may think it is an improvement.

And the required wiki entry:

Depleted uranium - Wikipedia, the free encyclopedia

I am also pretty sure it is very expensive.

depleted uranium is heavy, very heavy... look around you can buy the stuff.

Manufacturing Sciences Corp. - Oak Ridge, TN
Manufacturer, Custom Manufacturer
Company Profile: Manufacturer of flywheels made from depleted uranium for inertial & energy-storage devices.

Manufacturing Sciences Corp. Oak Ridge, Tennessee

 

[joeyg1973]

Why not? Solid steel I would think is the best option. Balance it and you're good to go.

Remember I am looking for cheap here, a piece of steel round stock large enough after machining would probably cost me about 2 grand.

 

[joeyg1973]

I actually just thought of this. How about a barrel with paddles/baffles on the inside so that it would move the weight of the water or liquid of choice and still allow it to be dynamically balanced. Perhaps even splitting the barrel into 2 or more segments internally so that the water needs to move when the barrel roles.

 

[zebrabeefj40]

That would be called a water brake. Most engine dynos use them AFAIK...

They work well and are far safer than a large, poorly engineered, flywheel.

You might also look into regenerative braking. IE use an electric motor as a generator or braking device to provide a load. Like the hybrids use the electric motors to slow down. Rail locomotives use the same principle on a much larger scale while decending mountain grades. Used electric motors are not that hard to come by.

Nick

 

[beaufort-fj60]

no joke on the depleted uranium flywheel.. it makes an awesome flywheel. Not very common, and yeah it might be dangerous.

 

[joeyg1973]

That would be called a water brake. Most engine dynos use them AFAIK...

They work well and are far safer than a large, poorly engineered, flywheel.

You might also look into regenerative braking. IE use an electric motor as a generator or braking device to provide a load. Like the hybrids use the electric motors to slow down. Rail locomotives use the same principle on a much larger scale while decending mountain grades. Used electric motors are not that hard to come by.

Nick

It's not a water brake, a water brake uses the pressure of pumping the water to create a static load on the engine that only measures performance at the rpm point the water brake is set up for. They are much more complex in design and require a lot of things that I really don't want to get into, like cooling towers. A heavy wheel actually gives you a dynamic reading allowing you to tune over the whole rpm range at once.

A drum with sealed or baffled segments containing water is using the water as weight, not as pressure as it is not moving anywhere. Without the sealed or baffled segments the water would just slide around as the barrel would spin. Eventually from friction alone, it would start to move, but the weight would not be consistent. The idea is to move the water immediately or very close to immediately after it starts.

It has the advantages of being cheap and self balancing. It also might be safer than a metal wheel as if it does fail, the barrel will fail and release the water and therefore the weight and force. One of the things I am concerned about with a metal or solid wheel is that the rotational force will cause the metal to fail and explode into shrapnel.

 

[Trollhole]

There is no way you will ever get a 2f no matter how well built up to 10k.

 

[joeyg1973]

There is no way you will ever get a 2f no matter how well built up to 10k.

agreed but it would be silly to build a dyno for just one motor and I want a large margin of safety here.

 

[malcb]

agreed but it would be silly to build a dyno for just one motor and I want a large margin of safety here.

Is this an engine dyno only and has to be one to one drive with no gearing?

Train wheels - good for the weight 500KG easy, newer types have a steel "tire" on the rim with rubber between them, almost a harmonic balancer. I think 125mph on a 1M wheel is about 1000RPM - lots of trains move at that or faster.

 

[Interceptor]

You live in a state with a failed emissions inspection program. About 10 years ago lots of shops were forced to buy $40k+ chassis dynos so they could do emissions inspections, now they're outdated and worth almost nothing. They were made by several of the big dyno companies (Mustang, Clayton). You can pick one up for a few hundred bucks. I bought one from a local GM dealer for $400. There was a guy in NJ selling the same one (Mustang) for $600 on Ebay last month. It has a large steel flywheel and a 150hp eddy current power absorber with load cell. It also has lots of pillow blocks and shaft couplers that may be useful in building an engine dyno. Mine's still a chassis dyno, I use it for tuning and road load sims. It's got 2000lb inertia plus the 150hp absorber. If you want to get real hp readings you'll need some decent data aq hardware/software.