Is Wikipedia Wrong About Torque?

Er. I don't want to seem more pedantic than normal but

Quote 1 is talking about the flywheel and says the maximum Torque is 18Nm.

Quote 2 is talking about the flywheel and says the Torque is no more than 18Nm.

Seems to me they're saying the same thing (although Q2 mixes up Power & Energy).

You're 100% right about going back the source though. A lot of reporting is simply a rehash of someone else's report which was a rehash of ...etc. It's a running joke in our house that things announced in "New Scientist" will get written up, months or years later, in the daily papers as the latest thing (occasionally with attribution).

The Wikipedia article is correct. The Racecar Engineering article is incorrect: as you point out, the unit does not "store" 60 kW.

The power is limited by the rule to 60 kW. The Energy storage capacity is limited to 400 kJ.

Although both articles are correct regarding the torque, they fail to mention that the reduction ratio is extremely high and infinitely variable. For an audience that does not follow this stuff, it would be helpful to give representative torques and rotational speeds at the output of the CVT or at the wheels. For example, if the car is accelerating out of a low speed corner, wheel rpm could be 1000, requiring a 64:1 overall reduction, and providing a 64 fold increase in flywheel torque (i.e, 64 x 18 Nm) at that instant. That is enough to make passing more feasible.

The Wikipedia article is correct. The Racecar Engineering article is incorrect

Oops, guess I ignored my own advice and didn't go back and find the ORIGINAL, original source that the Racecar Engineering article was based on.

Rotating power = Τ * ω so 18Nm * 64500 RPM * 2∏/60 = 60790 W

The article isn't clear how it uses this power, do they couple it to the wheels mechanically or do they run an electric alternator/motor. All up, it doesn't look like a huge amount of energy is being stored (compared to that produced by the IC engine)

It is not a lot of power - but the new F1 rules limit it to this amount.

Given the extra weight most of the teams are not sure that it will be any advantage, but even if it does not reduce lap times it can be a tactical advantage in overtaking.

It was expected that the KERS would be the big unknown variable in F1 this year, but now it seems the aerodynamic rules were badly worded and 3 teams have found a big loophole. The other teams are not happy....

Heres another thing I thought that torque was measured in Newton metres ?

18 Nm at a rotational speed of 64500 rpm results in 121.6 kW, not 60.790 kW.

If the power is limited to 60 kW there is something wrong with above numbers. I would also think that the 64500 rpm will be reduced to engine output shaft speed and not to wheel rpm. It would not make sense to have two transmission. One would feed to KERS power to the input side of the gear box. Or how is it done?

Since maximum engine rpm is near 18000 this year, I believe, (it used to be 19000) or say the power is used at 16000 rpm, the reduction ratio is roughly 4:1 (64000 / 16000). At this operating point the torque would be 4* 18 = 72 Nm input to the gear box.

Power comparison: roughly 850 hp = 625 kW. Adding 60 kW with KERS, assuming this is correct, would be near 10% of engine power.

Normal engine torque is about 625 kW * 9550 / 18000 = 330 Nm. Adding 72 Nm represents roughly 20% increase in torque at that point. This sure will help for passing. It may also cause spin outs if applied to upruptly, one could guess.

240 mm diameter and above 1000 rev/s is a pretty high speed and high centrifugal forces.

Does anybody know the internal construction, especially the bearing assembly?

The unit is very much worth while not only because boost in acceleration but on fuel mass reduced. So faster at start and most of the run. Milliseconds count in a race.

RHABE

Without touching on anything that the article is about.

Wikipedia is NOT considered a reliable source for information when citing references by practically all Colleges and Universities.

If you don't like the information you're reading in Wikipedia you can go in there and edit it yourself to read what ever you want it to read until someone else comes along and edits your changes.

I know very little about the specifics of this application, so I'm not an authority on this subject, but the limit of about 10Nm may be based on what level of negative acceleration is allowed.

(Radius^2 x weight) / 2 x gravity will give you the mass moment. Then apply the rate of acceleration (positive or negative) and you can calculate torque from there.

The earlier segment of the article touches on the need to limit how much regenerative braking is applied to prevent the tire(s) from locking up in poor road conditions. So max torque may not be limited by the flywheel itself.

... shouldn't it read 176 Nm ?

No. You are off by an order of magnitude. At least your error is smaller that the errors you routinely commit when describing your 1000 mpg car engine and your Pulse Jet engine.

It has been a year-and-a-half since you posted your Pulse Jet engine thread, but you have made no attempt to correct the most egregious errors (deliberate misstatements?) on your site, despite loads of patient tutelage from CR4 members.

I can only conclude that these "errors" are deliberate misrepresentations, although if you are simply insane, please accept my apologies.

This statement from your site is ludicrous:

The total pressure developed by a Rotary Pulse Jet Engine with a cylindrical combustion chamber (rocket pod) having a volume of 9" and a back wall diameter of 2.5" is ideally 1.25² x 3.14 x 500 = 2453lbsf, since both combustion chambers fire at the same time, the total pressure available during a single power stroke should be 2453 x2 or 4906 lbsf approximately.

The "back wall" diameter (and thus area) has no effect at all on the thrust of a rocket engine. Obviously the the "back wall" area could be quadrupled by a simple reshaping of your combustion chamber, without having any appreciable effect on thrust, which varies with the mass transfer rate through your nozzle, not with "back wall" area. This, and many, many other misstatements were pointed out by me and others, long ago.

Two recommendations:

Be honest. Do the math.

I think you need you show some sign of taking the advice of CR4 members (most of which has fallen into areas of basic high school physics) or else be considered to be a scam artist. I note that CR4 closed one of your threads even before there were any comments. You can take that as a sign that your claims are seen as rather "over-the-top." Perhaps I am jumping to conclusions, but from your posts here, it seems that you are of at least average intelligence. Therefore you cannot claim, I think, that the math is simply too difficult to do correctly: I don't think anyone has posted anything regarding your schemes that is beyond 5th or 6th grade level.

Remember... Be Honest, Do the Math. Take responsibility for your statements and actions. There must be a high school in your town. Go talk to the physics teacher and have him walk you through the calculations for rocket thrust. Learn about the meaning of words such as power, energy, thrust, force, pressure, torque.

No reply necessary; I am not subscribed.

Coming back to this thread. Look, torque = Inertial mass x rotational speed, so whether you are talking about the flywheel OR the axle, (the axle can be taken to mean a spinning object) it is still quite ridiculous to say that the torque is reduced because of the high rotational speed. Tell me if I am wrong. The physics says that torque should increase, which is the whole point of my question, not of whether it was the axle or the flywheel that was spinning!

P.P.P.S: I don't know why the thread was closed, it has been reported in reputed mechanics magazines and web-sites. What did I do wrong. I am not talking about my own invention but about another invention that is being used in Formula 1 racing today, namely the flybrid energy storage system. So what gives?????

p.p.s. It is not a rocket engine, think of it more as an inside out gun, and everything should start to make sense.

As was stated much earlier, power = torque times rotation speed. So if the flywheel rotates very fast, for a given power the torque is quite small.

A more pertinent question might be where this torque is being measured. The mechanical KERS use a continuously variable drive between the flywheel and the car transmission, so unless you are in the flywheel design business, the important part is the end of the drive that couples into the car transmission - where the speed will be far lower, the torque will be higher, and exactly how these relate to the flywheel will be under the continuous electronic control of the drive.

There is an alternative design where the flywheel is sealed in a vacuum chamber (= reduced losses) and power is put in and out electrically via magnetic coupling through the casing. Effectively it is a mechanical battery. No shaft torque to worry about. The third solution is actual batteries. All three options are under development for racing cars (sports as well as F1) so it will be interesting to see which comes out on top. And which causes the biggest accidents!