blaplante
Well Known Member
I'm thinking of some small changes that should increase the io-320's power output, potentially 1 or 2%. I'd like to be able to measure the performance, or relative power, to confirm the change actually did help.
Does anyone have a good idea on how to do that?
Current thoughts: measure WOT top speed, 3 way course. It needs to be done at the same density altitude for both tests, and the change isn't quick to do. Plus, any power improvement only increases top speed by the cube root (approx), so a 1% power increase will show as much less than a 1% speed change, which gets it down in the noise.
Rate of climb is much more sensitive, as it is proportional to excess power (above minimum flying power req'd). So a 1% power change gives at least a 1% increase in Rate of Climb. But it is totally sensitive to weight (I expect a 1% change in weight would also make a 1% ROC change). And, the rate of climb needs to be done across the same density (or pressure?) altitudes. Again repeatability within 1% seems difficult and so the change could get buried in the noise and measurement error. 1% of 1500 fpm is just 15 fpm.
Ideas? Strain gauges?
Thanks, Bryan
PS - fixed pitch prop, but I do have MP read out to 1/10 "
Does anyone have a good idea on how to do that?
Current thoughts: measure WOT top speed, 3 way course. It needs to be done at the same density altitude for both tests, and the change isn't quick to do. Plus, any power improvement only increases top speed by the cube root (approx), so a 1% power increase will show as much less than a 1% speed change, which gets it down in the noise.
Rate of climb is much more sensitive, as it is proportional to excess power (above minimum flying power req'd). So a 1% power change gives at least a 1% increase in Rate of Climb. But it is totally sensitive to weight (I expect a 1% change in weight would also make a 1% ROC change). And, the rate of climb needs to be done across the same density (or pressure?) altitudes. Again repeatability within 1% seems difficult and so the change could get buried in the noise and measurement error. 1% of 1500 fpm is just 15 fpm.
Ideas? Strain gauges?
Thanks, Bryan
PS - fixed pitch prop, but I do have MP read out to 1/10 "
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