Gidday Jack and all,
I guess it depends on exactly what two mowers you are comparing,we were talking about Victa so
I compared Victa bases of the same time period.
I called the mower base a low arch but think of it as a mid arch when I think low arch I think of this SupaSwift (see image).
"The Victa Mayfair was a low-mid arch lawnmower made by Victa "
The Mayfair uses the same base height as the Victa I looked at.
https://www.outdoorking-forum.com.au/forum/u...model-the-first-mayfairs-c1965-1968.htmlI was just looking at advantages and disadvantages over the different designs of mower
bases.
"I guess my argument is that increased airflow accompanied by restricted higher chutes
produced the same result as mid-arch chutes with less restriction."
I read that as a higher chute mower has a more restricted discharge compared with a
mid arch mower discharge .A restricted discharge works like a regulator no mater how
much air pressure you supply to the restriction your discharge volume will be
constant once you reach a certain discharge flow rate.
I still see the higher discharge mowers as having a less restricted discharge compared with
the low to mid arch mowers.
My point is by increasing the discharge area you get a greater flow rate dependent
on blade speed , the angle on the fluted blades etc.
"just like a garden hose, restricted flow increases velocity."
I find that a bad analogy for a high arch mower because when you restrict the
flow of a garden hose yes you get an increase in velocity but your flow rate is halved,
try filling a bucket with the hose restricted and then with the unrestricted hose,the unrestricted
hose will fill the bucket in half the time.
If you restrict the discharge more on the high arch mower compared with the mid arch you would
slow the clipping dispersal down and possibly clog the discharge port with grass.
The efficiency of a rotary cutting unit is directly related to the air flow within the deck.
If the discharge port is restricted air flow can be lower within the deck compared with the
unrestricted port.
The high arch mowers had more air flow compared with the mid arch mower ,bigger fluted blades
than the mid arch and a more unrestricted discharge ,comparing a VC to a Mayfair and other mowers.
High velocity sounds great but without a high dispersal rate with an unrestricted discharge port
you would just clog the discharge port with grass.It's like a balancing act changing one thing
effects another like more fan effect from the blades with a restricted discharge port can
waste power.
The Vortex mower ad says the blades only cut the grass but when you look at the blades in the
image you can see the fluted blades.I take it the mower has so much fan flow from the
angled fins on the disc that adding two more blades without increasing the discharge area
won't help in discharging the grass any better than if you used flat blades.
This is a great example as the discharge port is working like a regulator.
Looking at the information I see that's the conclusion I find.
Happy to hear any evidence that I have this wrong,it's the way I see the differences.
I realize I may be on a different tangent but I find the differences in mowers interesting
and any new information on mowers.
Glad to hear any conflicting points of view that's how you learn.
Regards
Max