parapente
Topic Author
Posts: 1936
Joined: Tue Mar 28, 2006 10:42 pm

SHP Vs Lbs Thrust

Prop engines are measured in Shaft horse power. Fan engines are measured in Lbs of thrust. The 2 are different. How does one compare the relative thrusts of 2 engines. Is there a formula?

jetmech
Posts: 2323
Joined: Wed Mar 29, 2006 2:14 am

RE: SHP Vs Lbs Thrust

Engine Power (by LH748i Nov 6 2007 in Tech Ops)

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair .

Jetlagged
Posts: 2564
Joined: Sun Jan 23, 2005 3:00 pm

RE: SHP Vs Lbs Thrust

Strictly speaking it is engines which develop shaft power which are measured in SHP. Aircraft jet engines don't so are measured in thrust units.

It is easy enough to convert power to thrust, or vice versa, but you need to know propeller efficiency as well. You could fit a more efficient propeller onto an engine and get more thrust from it, but the power output of the engine would be the same.
The glass isn't half empty, or half full, it's twice as big as it needs to be.

Buzz
Posts: 694
Joined: Sun Nov 21, 1999 11:44 pm

RE: SHP Vs Lbs Thrust

Hi Parapente, Buzz here. There are conversion formulas, we used to grind through them when I was going to college. I haven't used them in years... So for an accurate answer, see what JetMech, and Jetlagged have posted.

For a very rough approximation, 60% of the horsepower is more or less the pounds of thrust. Of course, it makes a difference if you're at cruise speed (and altitude), or waiting at the end of a runway and hoping you have enough power to take off. (grin) Propellers are more effective at low speed - move a larger mass of air more efficiently.
Those little Bede BD-5's with the tiny jet engine worried me - can it get up to flying speed before the end of the runway?

g'day

Who is online

Users browsing this forum: No registered users and 28 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos