Reciprocating weight tests ?

[Stan Weiss]

Since we are talking about accelerating a mass, Energy seems like the right way to define it.

If someone says, "for a given energy, a lesser mass will accelerate faster than a greater mass" the appropriate reply would be "duh".

if youre talling about acceleration there is time factor involved hence energy and time are where the power comes from

the reality is if on a transient power run of chassis dyno increasing rotational mass results in less power at the wheels, the engine is making the same power but a portion is being consumed in accelerating mass.

if you have no frictional losses and the gearing is 1:1 the flywheel torque will still NOT equal wheel torque as it is not in static equilibrium. A sum of moments will show you this

Energy is sufficient to describe the consequence of reduced mass to acceleration.

How about a real world example for us. So 2 kg @ 1 meter out accelerating @ 1 G. How many kw does it take?

Stan

[jimmy07]

all about physics.vancedyoutube

[David Redszus]

Consider a rotating mass as follows:

Mass....10.0kg.............12.0kg...........9.98kg
Radius....0.1m..............0.1m.............0.1m
MOI.......0.050kg m^2.....0.060kg m^2....0.0499kg m^2

rpm.......KE.................KE..........KE
1000......5.4................6.5..........5.4
3000.....48.8..............58.5.........48.7
6000...195.0.............234.0........194.6
9000...438.8.............526.5........437.9

KE = kg m^2 Rad/s^2

The only difference is a 2 kg increase and a 20g decrease in mass.
While we have not calculated forces due to acceleration, even steady state rotating
masses contain a significant amount of stored energy.

Acceleration calculations must include vehicle mass and gearing parameters.

[digger]

Since we are talking about accelerating a mass, Energy seems like the right way to define it.

If someone says, "for a given energy, a lesser mass will accelerate faster than a greater mass" the appropriate reply would be "duh".

if youre talling about acceleration there is time factor involved hence energy and time are where the power comes from

the reality is if on a transient power run of chassis dyno increasing rotational mass results in less power at the wheels, the engine is making the same power but a portion is being consumed in accelerating mass.

if you have no frictional losses and the gearing is 1:1 the flywheel torque will still NOT equal wheel torque as it is not in static equilibrium. A sum of moments will show you this

Energy is sufficient to describe the consequence of reduced mass to acceleration.

E=mc^2

[SchmidtMotorWorks]

E=mc^2

Right in the case of rotating parts like wheels, flywheels, crankshafts I prefer to simply compare MOI.

If the parts being compared are not convenient to model in CAD, use a trifilar pendulum

https://www.happresearch.com/blog/2018/ ... um-for-moi.

Use long wires, put a guide hole in the center of the disc to force the center of rotation with a pin.
Draw concentric circles on the disc to center wheels, they are amazingly accurate, fun and easy.

[SchmidtMotorWorks]

How about a real world example for us. So 2 kg @ 1 meter out accelerating @ 1 G. How many kw does it take?

Stan

I don't see how that is relevant to a discussion of comparing MOI on rotating parts.
I think it is much more direct to simply compare MOI of the parts in consideration.

If you want a formula or function to compute anything these days, just ask:
https://chat.openai.com/chat

I highly recommend it. It is amazing how much it knows about very uncommon subjects.
And it writes beautiful code.
I use it everyday at work, those of use that have learned to work with it have multiplied our productivity while reducing effort.

[digger]

How about a real world example for us. So 2 kg @ 1 meter out accelerating @ 1 G. How many kw does it take?

Stan

I don't see how that is relevant to a discussion of comparing MOI on rotating parts.
I think it is much more direct to simply compare MOI of the parts in consideration.

If you want a formula or function to compute anything these days, just ask:
https://chat.openai.com/chat

I highly recommend it. It is amazing how much it knows about very uncommon subjects.
And it writes beautiful code.
I use it everyday at work, those of use that have learned to work with it have multiplied our productivity while reducing effort.

you compare the MOI and then what? The answer is it allows you to work out the change in acceleration rate of a system, power consumed and so on.

[Stan Weiss]

How about a real world example for us. So 2 kg @ 1 meter out accelerating @ 1 G. How many kw does it take?

Stan

I don't see how that is relevant to a discussion of comparing MOI on rotating parts.
I think it is much more direct to simply compare MOI of the parts in consideration.

If you want a formula or function to compute anything these days, just ask:
https://chat.openai.com/chat

I highly recommend it. It is amazing how much it knows about very uncommon subjects.
And it writes beautiful code.
I use it everyday at work, those of use that have learned to work with it have multiplied our productivity while reducing effort.

Well one could compare the 2 parts. But since I am lazy I just used an example of comparing the difference of the 2 parts.

Stan

Moi_ST.gif

[SchmidtMotorWorks]

you compare the MOI and then what? The answer is it allows you to work out the change in acceleration rate of a system, power consumed and so on.

MOI is all that I need to evaluate the parts with regard to acceleration.

[SchmidtMotorWorks]

Well one could compare the 2 parts. But since I am lazy I just used an example of comparing the difference of the 2 parts.

Stan

Moi_ST.gif

If that is interesting to you, enjoy it.

[Stan Weiss]

Well one could compare the 2 parts. But since I am lazy I just used an example of comparing the difference of the 2 parts.

Stan

Moi_ST.gif

If that is interesting to you, enjoy it.

Please post something useful and not just everyone doesn't know what they are doing!!!!!!

Stan

[SchmidtMotorWorks]

Please post something useful and not just everyone doesn't know what they are doing!!!!!!
Stan

I did that previously, I provided some tips on making a good trifilar pendulum.

I'll add that it is worth making them in various sizes, and having the pivoting pin is crucial if you want to do crankshafts.

[David Redszus]

E=mc^2

What units should we use for m and c?

[digger]

you compare the MOI and then what? The answer is it allows you to work out the change in acceleration rate of a system, power consumed and so on.

MOI is all that I need to evaluate the parts with regard to acceleration.

what is the consequence on the power measured when you lower MMOI on a chassis dyno that uses a controlled acceleration rate?

[289nate]

This is interesting. But I don’t believe it wins races as presented.