Random Thoughts - Part Deux [NO POLITICS]

[krayzie]

Originally Posted by Ultramaroon

Samir, you have to listen.

Shaddup!! Don't tell me how to drive.

[Tcoat]

Originally Posted by Spuds

I also just realized that I F'ed up at least the speed vs time data. Didn't match the time scales. Its late and linear interpolation is kicking my ass right now lol...

Sorry, Im tired and didn't really think to explain it lol.

First couple rows are calculating the output of the engine in the current configuration (Crank output). Since I know the total weight of the vehicle, I know how much kinetic energy must have been imparted to it assuming a solid body. I then add the energy from the rotating components we care about to figure out the total engine output. Note, other losses are assumed to be taken directly from engine output. Not exactly accurate, but close enough for a hobby.

Then I remove losses from the new configuration until I get a "Useful Torque" number, which is what is left to accelerate the car linearly. Because that linear acceleration can be used to calculate the angular acceleration of the crank (no wheel slip and known reductions), I can close the loop and iterate, assuming the output of the engine will remain roughly the same as my initial calculations regardless of how fast it accelerates. I just do that 10 times and we converge on a solution.

Yay Math... zzzzzzzzzzzzzz...

Originally Posted by Ultramaroon

He's actually doing some interesting stuff. I get the gist of the iterative process but I don't yet understand the need for, or the relationship between all the inputs.


I'm focusing more on explaining and then justifying my approach to a really simple model that aims to say "If we neglect all these things, we err significantly on the side of making the pulley seem more important than it actually is."


Then I do the math to get a realistic but small value.

[nikitopo]

Originally Posted by humfrz

No pulleys! ......

I thought that pulley thing was the objective of the whole exercise.

Where did I fall off of the turnip truck .......??




humfrz

Originally Posted by Spuds

I've been sitting on this for a few months now.

It is not that difficult. You can make a rough calculation using the flywheel calculator here:
http://hpwizard.com/rotational-inertia.html

On a crankshaft pulley most of the weight is on the outside part, so a model would be something like:

Outer diameter: 14cm, Inner diameter: 8cm
Stock mass: 2.2kg, aftermarket mass: 0.4kg

Gains in 1st gear ~15 kg
Gains in 2nd gear ~6.5kg

It might not sound that much, but you have additive gains from the other pulleys too and also some more if you underdrive the alternator. In general the secret is that you remove weight from rotational parts before the gearing

And I'll say again that this is a very rough model. A better model would calculate also how fast the FA20 engine increases the RPMs. Then you would find that in specific areas the gains are more, because of more acceleration.


Same holds for a flywheel ...

[Tcoat]

Oh god not here!!!

[Leonardo]

There are squirls barking at eachother on the branch just outside my bedroom window!

SHUT UP!!! I was trying to sleep!!!!

[Tcoat]

Originally Posted by Leonardo

There are squirls barking at eachother on the branch just outside my bedroom window!

SHUT UP!!! I was trying to sleep!!!!

They are debating the benefits of light weight walnuts. Light ones are easier to carry but the heavier ones stay buried better.

[Leonardo]

Originally Posted by Tcoat

They are debating the benefits of light weight walnuts. Light ones are easier to carry but the heavier ones stay buried better.

Ha ha ha ha!!! I just literally LOLd so hard I spit coffee out my nose!!! Now, my wife wants me to tell what was soooo funny!!!!!

[Spuds]

Originally Posted by nikitopo

And I'll say again that this is a very rough model. A better model would calculate also how fast the FA20 engine increases the RPMs. Then you would find that in specific areas the gains are more, because of more acceleration.


Same holds for a flywheel ...

There are two likely scenarios here, and I will for the last time address then both. You may pick whichever one works for you, but please let the community know so I can address you properly.

1. You are incapable of understanding that what you just described is exactly what I offered to do 4 or 5 times. My preliminary calculator is posted a few pages back. I didn't include pulleys because I didn't feel like looking up all the weights and diameters. If you want the calculations done, you would have had to put in some effort on your own end. If this is the case, you really aren't as smart as you think you are.

2. You are here to troll. Again. If this is the case, you F'ed up big time.


Either way, bringing the one topic up that you know @ichitaka05 has asked not be brought up in one of the few threads he actually participates in is not a good idea, especially when you have your own thread that you abandoned. Hopefully this will be the last we hear from you.

[Spuds]

Originally Posted by Leonardo

Ha ha ha ha!!! I just literally LOLd so hard I spit coffee out my nose!!! Now, my wife wants me to tell what was soooo funny!!!!!

If I'm looking at my phone and laugh, my fiance looks at me and says "Car forum things again?".

PS, she likes the cat gifs in the gif thread.

[Sapphireho]

Too much beer and poker last night. I came in 3rd in the hold'em tournament, so not too bad.

[Tcoat]

Originally Posted by Spuds

If I'm looking at my phone and laugh, my fiance looks at me and says "Car forum things again?".

PS, she likes the cat gifs in the gif thread.

My wife just says she knows I am on because I get a "goofy grin". She is not as impressed when I wake her up with laughing so hard at 2am. She was not happy with Ultra for about a year back in the heyday of the late night laughfests.

[nikitopo]

Originally Posted by humfrz

No pulleys! ......

I thought that pulley thing was the objective of the whole exercise.

Where did I fall off of the turnip truck .......??




humfrz

Originally Posted by Spuds

There are two likely scenarios here, and I will for the last time address then both. You may pick whichever one works for you, but please let the community know so I can address you properly.

1. You are incapable of understanding that what you just described is exactly what I offered to do 4 or 5 times. My preliminary calculator is posted a few pages back. I didn't include pulleys because I didn't feel like looking up all the weights and diameters. If you want the calculations done, you would have had to put in some effort on your own end. If this is the case, you really aren't as smart as you think you are.

2. You are here to troll. Again. If this is the case, you F'ed up big time.


Either way, bringing the one topic up that you know @ichitaka05 has asked not be brought up in one of the few threads he actually participates in is not a good idea, especially when you have your own thread that you abandoned. Hopefully this will be the last we hear from you.

I saw your file before and I thought to help you. I didn't bring the discussion here. You did and @humfrz, but it looks you are a very rude person with no manners and you don't deserve any help. Too bad I replied.

[Spuds]

Originally Posted by Tcoat

They are debating the benefits of light weight walnuts. Light ones are easier to carry but the heavier ones stay buried better.

Yeah, those heavier ones just sink like a rock into the turned ground. But both squirrels would be wrong though, since lightweight acorns are clearly the best nut stash mod one can get. I skimmed through an article that says they vibrate at a frequency that let's you get more nuts in the hole.

[Tcoat]

Originally Posted by Spuds

Yeah, those heavier ones just sink like a rock into the turned ground. But both squirrels would be wrong though, since lightweight acorns are clearly the best nut stash mod one can get. I skimmed through an article that says they vibrate at a frequency that let's you get more nuts in the hole.

True but they should not be used unless inspected and approved by a certified nut inspector.