flail mowers waist HP?

[955Lincoln]

I don't have either type of mower and don't follow these threads closely but has anyone considered the amount of wind resistance a flail must overcome? I'll bet just spinning and not cutting anything the flail sucks a lot more power than a rotary. Especially with the duckbill blades.

 

[Marveltone]

if you have a 48 inch width rotary cutter only one blade is cutting with the other following at all times allowing 24 inches of exposed cutting edge

A flail mower wil have one hundred percent coverage per my previous explanation as the gras slicers overlap due to the grass slicer becoming an airfoil becoming horizontal and achieving the zero degree angle from its fourty five degree angle at rest.

This does not occur on some brands of flail rotors as the knives are restrained vertically and there is a longer cutting edge per knive which eliminates the need to allow the knive to become an airfoil and achieve a zero degree angle.

That wasn't my question. I didn't ask about coverage, I asked what percentage of available blades were actually cutting. If there are four rows of blades around a cylinder, it's physically impossible for all blades to be at the bottom where the grass is. The other three rows are busy swinging their way around until they make their way to the bottom where the grass is. It's like a rolling pin; Only one small section is actually doing the work at any given time.

Energy is spent moving those blades around to await their turn to cut.

Joe

 

[hosspuller]

I don't have either type of mower and don't follow these threads closely but has anyone considered the amount of wind resistance a flail must overcome? I'll bet just spinning and not cutting anything the flail sucks a lot more power than a rotary. Especially with the duckbill blades.

Bingo !! Plus does a flail cut a blade of grass multiple times?? Each time encountering resistance??

Move fast enough and one could rake & bale grass cut with a RC. Would have to vacuum up the "chop" after a flail mower?

 

[leonz]

One third to one fourth of the total grass slicer blade count is mowing at one time depending upon whether the unit is a three row unit or a four row rotor with 16 pairs of knives and the odd knive provide 49.5 inches of exposed Horizontal cutting surface when the individual knives become individual airfoils.

A tapered cutting edge grass slicer becomes a very efficient airfoil like an airplane wing. The standard grass slicers that do not have the tapered cutting edges are less aerodynamic than the tapered grass slicers.


EDIT: big whoopsie on my part; A two row flailmower would have fifty percent of its knives mowing at any time.

_________________________________________________________________
Once you go flail you never go back:thumbsup::licking::drool:

 

[leonz]

Bingo !! Plus does a flail cut a blade of grass multiple times?? Each time encountering resistance??

It will do this if a very slow crawl is occuring.

==================================================



Move fast enough and one could rake & bale grass cut with a RC. Would have to vacuum up the "chop" after a flail mower?

Each knive encounters resistance from the surrounding air and the thickness of the grass and brush it is cutting.

At one time The New Holland farm equipment folks had flail attachments for their hay balers that used a flail chopper to gather corn stover and bale it.


The rotation of the rotor overcomes the resistance of the grass or brush it encounters but it is less effective if the implement carrier is advancing too fast for conditions.

As the rotor passes over the sod it will slice the grass/brush it encounters and the following blades overlap and slice the grass/brush to a lower hieght.

 

[Farmwithjunk]

Wind them up and stand back!

I'm starting to buy into the theory Leonz is a paid spokesman.....for the rotary cutter industry!


Or else he's Obama's speech writer....

 

[Farmwithjunk]

Seems the bait has been taken!!

Now ya give 'em some line, let 'em run a bit while ya open up the door on the live well.....

 

[SPYDERLK]

The typical flail mower or flail chopper has more cutting edge surface exposed to the grass or brush versus the rotary cutter of any cutting width width as the rotary cutters exposed cutting edge is in actual use half of the mowers width with one mower blade always trailing the first advancing blade.

The flail mower or flail chopper has many more feet of cutting edge exposed doiing the same work at a higher speed of rotation at all times as the flailmower rotor is spinning at a much higher RPM due to the V belt drive or gear drive of a flail chopper.

If anything the flail mower has a higher efficiency simply because it has more cutting edge exposed doing the same work along the entire width of the mower at work.

_________________________________________________________________
Once you go flail you never go back:thumbsup::licking::drool:

Please post your definition of efficiency.
larry

 

[leonz]

The six items below are my reasoning a flail mower is more efficient
in my opinion.


1. Higher output R.P.M. speed at the final V belt drive pulley with
the same 540 rpm output speed to allow flail motor rotor speeds
of up to 220 miles per hour depending upon the individual
manufacturers flail mower model.

2. More total cutting edge length in use per foot of mower and cutting
width versus other mowers-excluding reel mowers for golf turf which slice
the grass into even smaller clippings.

3. Slicing of grass and brush into shorter clippings per revolution
of the flail mower rotor reducing the load on each grass slicing
knive by distributing the slicing between two three or four rows of grass
slicers.

4. Each grass slicer has an identical opposite sharpened edge
which increases the total cutting edge by one hundred percent
allowing a total of 200 percent of available cutting edge to do
work.

5. A grass slicer with a hardened cutting edge will last longer in
use increasing its service life.

6. A grass slicer Y blade is easier to sharpen using a wet knive
grinder or touching them up using a table belt sander.
.

 

[SPYDERLK]

The six items below are my reasoning a flail mower is more efficient
in my opinion.

Please post your definition of efficiency.
larry

 

[leonz]

Please post your definition of efficiency.
larry

The "Verticut" method of grass and brush mowing as item no. 7.

 

[SPYDERLK]

:confused2: So ... Are you researching in prelude to composing your definition of efficiency?, or should I just assume its wrong?
larry

 

[beppington]

IMO rotary cutters & flail mowers do 2 different things, enough so anyway that I'm not sure it makes sense to argue which one is more efficient.

Rotary cutters generally provide a rougher looking finished cut. But they also can cut heavier vegetation, compared to a flail that requires the same PTO HP. They will leave larger pieces/ clumps of stuff.

Flail mowers generally provide an almost-lawn finished cut. And the size vegetation that can cut is smaller, again compared to a rotary that requires the same PTO HP. They will leave smaller pieces, usually that you can't really see; It takes more HP to do that than to just leave big clumps of stuff.

If you want to beat up big stuff & are OK with a rougher looking finished cut, get a rotary. I think of a rotary as the mower to use when you'll be mowing big stuff & you don't know for sure what might be in there, or it's been overgrown for a loong time.

If you want a near lawn cut & are OK knowing it won't cut stuff as big as a rotary, get a flail. I think of a flail as the mower to use when you're mowing a lawn or field that's grown up some, not too long, but where you're pretty sure you're not going to encounter anything big.

 

[RickB]

6. A grass slicer Y blade is easier to sharpen using a wet knive
grinder or touching them up using a table belt sander.
.

Anyone claiming that sharpening a hundred or more blades of any style and configuration is easier than sharpening two rotary cutter blades has been out in the sun too long, or thinks the rest of us have been. An equal number, maybe. But never in apples-to-apples full set quantities.

 

[leonz]

What definition of efficiency are you asking me for?

Is it the definition of power in terms of force, distance moved in time?


Power= force x distance moved divided by time.

An over sized comparison to a hammer flail mower would be the "Pennsylvania Crusher Companies Bradford Breaker Hammer Mill Sizer" which is also operates on a horizontal axis.


Unfortunately for me I am not computer literate enough to type the formulas for rotating bodies and throw wieghts of objects attached to them.

 

[greg_g]

Anyone claiming that sharpening a hundred or more blades of any style and configuration is easier than sharpening two rotary cutter blades has been out in the sun too long, or thinks the rest of us have been. An equal number, maybe. But never in apples-to-apples full set quantities.

I'm guessing you've never touched up flail knives. It's a simple job with a rotary tool fitted with an emery stone. My flail has 66 double knives - 132 little edges - all of which takes me about 30 minutes to sharpen on the machine. My rotary cutter on the other hand, takes me 20 minutes to drop the blades, 10 minutes each to vice grind them, and another 20 minutes to reinstall. Not as many busted knuckles sharpening flail knives either.

//greg//

 

[Farmwithjunk]

I'm guessing you've never touched up flail knives. It's a simple job with a rotary tool fitted with an emery stone. My flail has 66 double knives - 132 little edges - all of which takes me about 30 minutes to sharpen on the machine. My rotary cutter on the other hand, takes me 20 minutes to drop the blades, 10 minutes each to vice grind them, and another 20 minutes to reinstall. Not as many busted knuckles sharpening flail knives either.

//greg//

I don't know why anyone would want to take off rotary blades in order to do a simple touch up, then re-install. A waste of time IMHO, not to mention repeated re-torquing bolts tends to eventually distort threads/stretch bolts. It takes about 15 to 20 minutes to touch up SIX blades on a bat wing with a 4-1/2" grinder. (Did 2 mowers today in fact) NO busted knuckles either....

 

[RickB]

I'm guessing you've never touched up flail knives. It's a simple job with a rotary tool fitted with an emery stone. My flail has 66 double knives - 132 little edges - all of which takes me about 30 minutes to sharpen on the machine. My rotary cutter on the other hand, takes me 20 minutes to drop the blades, 10 minutes each to vice grind them, and another 20 minutes to reinstall. Not as many busted knuckles sharpening flail knives either.

//greg//

If it took me 20 minutes to get the blades off my rotary cutter every time, I'd sell it. It's about a 5 minute job on a single-spindle machine if you know what Never-Seize is.

 

[DK35vince]

I'm guessing you've never touched up flail knives. It's a simple job with a rotary tool fitted with an emery stone. My flail has 66 double knives - 132 little edges - all of which takes me about 30 minutes to sharpen on the machine. My rotary cutter on the other hand, takes me 20 minutes to drop the blades, 10 minutes each to vice grind them, and another 20 minutes to reinstall. Not as many busted knuckles sharpening flail knives either.

//greg//

I've never removed a rotory cutter blade on my mower to sharpen it.
5 minutes and an angle grinder is all I need.

 

[Farmwithjunk]

So.....I wonder if the OP has his answer yet?