There has been a lot of discussion lately about prop thrust and how
it affects aircraft performance so I started a dissertation on
the subject.

It all has to do with the definition of HP.
In theory one HP could move a mountain.
Rather surprising result I would think.

The definition of HP is force times a speed.
Namely 550 pounds moving at 1 foot per second or 1100 pounds
at .5 FPS or 2200 pounds at .25 FPS or 5500 pounds at .1 FPS
or 55,000 pounds at .01 feet per second. You get the picture.

So if it is going slow enough the force could approach infinity.
The same thing applies to thrust.

In theory a 200 HP aircraft engine could put out tens of thousands
of pounds of thrust at 1 MPH. This would in fact happen
if we were feeding the engine HP into a gear box and used a super large
prop. In other words a hovering helicopter.


What happens in aircraft application is poor slow speed prop efficiency
rears its ugly head. More about that shortly.

I'll let you think about this while I work on refining this spread sheet.
The graph shows THEORETICAL thrust as a function of MPH for a 200 HP engine.
The blue curve is feet per second. The red curve is theoretical thrust.