Converting MOI from SI to imperial ??? How?

[JEL]

Hello

I am trying to calculate a set of 'moments-of-inertia' values from SI-standard to imperial standard, but I'm not sure I'm doing it correctly. So I was hoping someone could perhaps double-check my numbers.

I have these original values:

Ixx = 1.1829 * 10^8 kg/m2
Iyy = 8.8239 * 10^8 kg/m2
Izz = 9.0297 * 10^8 kg/m2

and my calculated results are this (decimals omitted on purpose):

Ixx = 24227689
Iyy = 180727629
Izz = 184942743

Theyre supposed to be in lbs/ft2 (which I believe is aka: Slug-ft^2, which is what I'm trying to convert into), but like I said I'm not sure I'm doing the conversion correctly.

I'm dividing the SI-numbers with 4.88243 to get the lbs/ft2

Can someone confirm my results, or explain how to do a correct conversion (ultimately into Slug-ft^2)

Thanks
JEL

 

[Chode]

The units for inertia are mass * length^2. So your original values should have units of kg * m^2, and not kg / m^2. If you calculate the conversion from kg * m^2 to lb * ft^2, you should get the correct result.

Regards

 

[mjessick]

A trick for using English units: always differentiate between pounds force and pounds mass (lbf and lbm). I wouldn't use pounds anything anyway. The most useful units are slug ft^2

 

[Quick_Nick]

Handy Moment of Inertia conversion table:
http://www.engineeringtoolbox.com/moment-inertia-torque-d_913.html

 

[James.Denholm]

A trick for using English units: always differentiate between pounds force and pounds mass (lbf and lbm). I wouldn't use pounds anything anyway. The most useful units are slug ft^2

And pounds sterling! And English pounds, and Egyptian pounds, especially if you're in a taxi in Egypt... read about a scam in a Lonely Planet. And went there.

 

[simonpro]

A trick for using English units: always differentiate between pounds force and pounds mass (lbf and lbm). I wouldn't use pounds anything anyway. The most useful units are slug ft^2

There's useful imperial units?

 

[James.Denholm]

Now you see why metric was invented.

EDIT: No base 12 or anything, all base 10...

"4 plus 4 is 10... IN BASE 8! I'm FINE."

Ah, poor, poor confused GLaDOS.

 

[Urwumpe]

There's useful imperial units?

I like cables and fathoms. :lol:

 

[JEL]

The units for inertia are mass * length^2. So your original values should have units of kg * m^2, and not kg / m^2. If you calculate the conversion from kg * m^2 to lb * ft^2, you should get the correct result.

Regards

Well, I just copy-pasted the values directly from the pdf-document
(you can see a snapshot here: http://home.tiscali.dk/8x066050/JELAIR/FlightTestCenter/TEMP/ )

Handy Moment of Inertia conversion table:
http://www.engineeringtoolbox.com/moment-inertia-torque-d_913.html

Thank you very much Now I get values I can understand
JEL

 

[dutchpirate]

Cubits!!:rofl:

 

[Notebook]

There's useful imperial units?

Yes, a very good unit the Horse Power, you can see exactly what it does. Also its not a vector, it only travels in a straight line.

N.