All ergs are partial simulators, with many assumptions built in.
The original RP flywheel is a disc of steel, 430mm diameter & 3mm thick,
with 8 radial blades, 50mm wide & with 13mm right-angled flanges, each
blade 183mm long & 2mm thick, attached to one face by their 13mm
flanges. That should be enable you to derive the wheel's MI?
The flywheel accumulates and stores kinetic energy with a V^2
relationship, as do the moving masses of your body & boat.
As the fan element of the flywheel is anything but an ideal piece of
turbomachinery, it is not as peaky in its efficiency vs angular velocity
relationship as more refined fan systems & is thus more likely to
reasonably represent the square-law relationship of drag vs angular
velocity over the operating range.
To properly measure the power input requires a dynamometer - constantly
measuring force in the chain or belt & its speed of movement.
Calculations based on flywheel inertia & rate of run-down make
assumptions of a relationship between velocity & drag which are not
necessarily accurate, given the inevitable peakiness of the
speed/power-absorbed relationship of the various fan types. This has
been demonstrated by applying dynamometers to ergs & comparing the
results. And, please note, due to the time lags in surrounding air
flows resulting from the constantly varying flywheel speed & air
throughput, erg computer results can be further at variance from actual
work being done & are not necessarily representative of rower power
Next there's the increasing fixation on erg results for comparison and,
worse still, for crew selection. Rowing technique is so very different
from static-erg technique, since those ergs' dynamics involve rapid
changes in body mass velocity which are entirely absent in rowing. Thus
you have to decelerate the body as you approach the catch on a fixed erg
& much less so on a RowPerfect, while in a boat (despite what coaches
like to tell you to do) the notion of decelerating your movement down
the slide is actually meaningless since you are not moving down the
slide but are actually pulling the foot-stretcher, with the boat,
towards you. (Distant cries of "anathema" & disbelief?)
So perhaps we should not be too fixated on what the erg computer tells
us, but see the erg as another kind of weight-lifting machine with a
rather closer relationship in the necessary movements to a real boat,
while the boat itself is a delicate, responsive instrument demanding a
range of techniques, skill & finesse which are entirely absent from the
erg room. And doesn't some of the rowing we see highlight that crucial
Carl Douglas Racing Shells -
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