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Type: Posts; User: 19jaguar75

1. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### Hmm, the airplane engineering book says...

Hmm, the airplane engineering book says otherwise.
I have data for a couple balanced cranks so I am going to see which method works best, with and without those expansion forces.
That is once I get...
2. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### At smartconversion there is no option for using...

At smartconversion there is no option for using meter/second in its force calculator (which I thought was correct), only meter/second^2. Using that I calculate 10368 as the velocity change, not 2.88...
3. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### As an engineering "outsider" I question all...

As an engineering "outsider" I question all previous assumptions. In this case the assumption that the compression and combustion pressure counter the upward inertia force of the piston. To...
4. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### Please do share my idea. I think the idea of just...

Please do share my idea. I think the idea of just adding a percentage of rod weight to the piston assembly and a percentage of the rod weight to the crank is terrible.
OK please bear with me as I...
5. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### My piston moves .8mm the last 15 degrees to TDC....

My piston moves .8mm the last 15 degrees to TDC.
It weighs .1166 kg
Time of 15 degrees is .00028 sec
.0008 meters / .00028 sec = 2.88 m/sec velocity

Using the normal mass x acceleration formula...
6. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### When I multiply the 1/4 rod section kg by its...

When I multiply the 1/4 rod section kg by its velocity change x .0209 I get a very miniscule amount.
What am I doing wrong?
7. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### This engine is fairly well balanced and I just...

This engine is fairly well balanced and I just calculated the counter balance force which is also way up there. So without counter balance these engines would probably shred themselves right away....
8. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### OK but here's something I perceive as a problem:...

OK but here's something I perceive as a problem:
For my small 55cc engine with 116.6 grams piston assembly weight (piston, wrist pin, bearing, and the part of the con rod that wraps around the...
9. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### Cragyon, you may be smarter at math than I am but...

Cragyon, you may be smarter at math than I am but at least I know how to directly answer questions (when I know the answer).
You didn't answer my question. Nor did you give me the clue to do so....
10. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### OK so if I use kilograms for mass, and meters for...

OK so if I use kilograms for mass, and meters for length then what measure does the equation give? (N/m^2, Newton meter, Joules, etc)
11. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### OK then please tell me if the result is in...

OK then please tell me if the result is in Newtons, newtons/meter, or Newtons/meter^2

I'm confused as to the variations in different measures- N/meters, N/meters^2, pound foot, pound foot^2
What...
12. ## Thread: inertia formula for con rod

by 19jaguar75
Replies
1
Views
3,072

### inertia formula for con rod

I am trying to calculate all the forces (in lbf) that the connecting rod adds to the engine which influences vibration.
I am dividing the rod in between the two ends into four sections and...
13. ## Thread: 2 stroke piston inertia formulas

by 19jaguar75
Replies
20
Views
1,770

### 2 stroke piston inertia formulas

hi all
I need help understanding this formula.
Here's my rewrite of it:

piston assembly inertia = Reciprocating Mass * CRANK RADIUS * W^2*(COS(Wt)+(crank radius/rod length)*COS(2*Wt))
...
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