Autosport Labs

Which engine accelearation units make the most sense?


rev/sec^2, rev/min^2, rev/ms^2


Which of these are usable?

RPM

Ok RPM is a speed vector, it don't make much sense to me.

For example, if engine used to be at 1000 RPM a second ago, and now it is 2000 RPM, accelearation is 1000 revolutions per second^2, or 60000 RPM^2, or 16 revolutions per milli second.

RPM per second is the industry standard.

I would venture that this is because the dividend doesn't need to be converted for other calculations and the divisor keeps the significant digits to a minimum.

Using your example, the acceleration of the engine is 1000RPM/second, NOT /second^2. ie 1000rpm increase in *speed* over one second, since acceleration is difference in speed over time, the unit of acceleration is RPM/Sec

im not sure where youre 60000RPM/sec^2 came from???.

RPM/ sec comes from

a revolution = Distance, a displacement
a revolution per unit time(eg minute) = Velocity, RPM
a revolution per unit time, per unit time, = Acceleration, RPM/sec

Carrying this on, the RPM/sec^2 is the differential of acceleration, giving a function called jerk which isnt really of any use unless youre designing, it especially isnt acceleration, its a measure of the rate of change of acceleration.

RPM is already a velocity, i think thats where the confusion came in..

Therefore an acceleration is a displacement/time^2, OR (displacement/time)/time ie-(RPM)/sec. Hope this helps! .Al

sweet hellfire i got carried away there sorry!

First one is RP(S)^2, actually. Second is RP(M)^2, third RP(ms)^2. Or R/s^2, R/m^2, R/ms^2. All of these are R over time square. Where R is a constant measuring revolutions.

RPM on the other hand, or R/M, is a vector, not constant. It has magnitude R, and direction t.


You made an effort there buddy, but nah.


I'm going with RPM/1s for my program, it seems to make the most sense, and calculations are way too simple, basically a simple subtraction.

OO that sounds like fightin' talk! This could be going on a long time..

"First one is RP(S)^2" i duno what that means! RP (in the unit of seconds) squared?...And veclocity (RPM) IS a vector yes thats the only way calculus can work!

Its a simple displacement, velocity, acceleration situation, with displacement in revs (a vector displacement, but since the crank ROTATES on ONE axis this vector is either + or - in direction) and the other two first and second order differentials..

You are right to be using RPM/SEC as it has units of (displacement/time^2,remember RPM already is displacement/time) whereas RPM/sec^2 as you had before has units of displacement/time^3..

I did put effort in...and im not giving up that easily!:P trust me man..i'm 99.9% certain that makes sense, it does to me!

love,
.al

I never said RPM/sec^2, fool. That's the problem with you fools, you know math but can't read the problem at hand. You either misread my original post, or you read what other fool posted. Post from other fool said RPM/sec^2, that's why I replied to him to correct him. And now you.


My original post "accelearation is 1000 revolutions per second^2, or 60000 RPM^2, or 16 revolutions per milli second."


I see here second^2, minute^2, and milli second. The only thing to correct is that milli second should be squared.


Keep piling your junk comments buddy.

AND in the first original I use rev/time^2. Fool. ;-(

ya gettin shirty there! in fact screw it u gettin downright shitty!

your comment 1000rev per second squared is bollocks anyway coz its 1000revs per minute per second, looks like im not the only one paying attention to units?!

sure i got the wrong end of the stick, now i look over it i can c ur first 2 on original post was ok units wise, was just not in the standard format of a change in velocity over time, but surely u understand i was ONLY trying to help ?

The thing is, my math was right, the unit was right, so whats the problem? so long as its some change in vector velocity over time (or displacement over time^2) its cool...tell me i havent been trying to prove that all along?

albeit with the wrong end o the stick..

relax..really..were all friends here eh?

.Al

Look- there's no reason for personal attacks. This needs to stop, now.

In fact I never thought I'd have to write a message like this.

Ok, back to ignition controllers.

Fact is, I never said time^3. Some people replied assuming I said time^3. What happens if you go smart about a math problem whithout understanding what it was all about? You get rediculed.

Official units for my runtime display's engine acceleration are RPM/second.