# Rotational drum torque and hp

1. Dec 30, 2011

### sniffy

Hi there,
I posted essentially this question a quite awhile ago but the answer wasn't what I needed and then the post got hijacked so I'll try this again worded differently....

I need to figure out the torque and hp required to rotate a steel drum, both for acceleration and to maintain its rpm. Its an 11 inch diameter sch40 pipe welded onto a 2-1/2" solid shaft. This rotating mass is 650 lbs and spins at 1650 rpm. I need to be able to tell the Hydraulics shop the force needed so that they can order the correct pumps and motors. (Assume bearing friction is minimal)
Here are the details and what I've gleened off the net so far.

Mass 650lbs (295 kg)
Outer diameter 11" (28cm)
Length 96" (244cm)
Shaft diameter 2.5" (6.4" )
Rotational speed 1650 rpm = 27.5 rps = 950 in/sec = 79 ft/sec = 172.8 rad/sec
Acceleration 0-1650rpm (at 10sec)= 7.9 (at 20sec)=3.95

Moment of Inertia (I) M*r^2 = 650 x 5.5^2= 19662.5

After this point I obviously start making errors because I end up with an answer of over 1003560 ft/lbs needed. ;\