az_gila
Well Known Member
A thread from 2 days ago linked to an EAA video about finding Vx and Vy. However the EAA video seemed to ignore weight and density altitude.
If we have a good EFIS - my remarks are for a Skyview system, but I assume the competitors are similar - data entry is made simple, with more variables collected than you know what to do with.
Nice graphs can be made with a free subscription to savvyanalysis.com. So I was thinking can all of this data be extracted and normalized into a POH for your plane?
After examining the performance data from my certified Tiger POH I have extracted some data constants. I hope simple data analysis and conversion with Excel will do the trick.
Need confirmation from any aerodynamics experts on stuff below.
1. Taking the climb rates from the POH I extracted a straight line that gave a -6.422% drop in climb rate for each 1,000 ft of std day.
Q. I assume that if I convert my flight test altitudes to a Density Altitude this constant will remain the same. Is that correct?
DA has been high during my testing so far, and these individual climb rates were taken at various speeds at DAs ranging from 5,500 to 15,000 with most at 8000-9000. The aircraft weight as not been corrected by are for pilot and about 3/4 fuel.
The curve seems reasonable and sort of shows my 83 inch pitch Sensenich is probably a climb prop.
The confusion I had extracting data from the Tiger POH was that the IAS for max. climb rate changes by std day altitude. The factor was -1.282% per 1000 ft.
Q. Does that make sense? I thought DA would correct for this and IAS remain constant. If not, how do I apply this correction factor to the above data?
More questions to come, but that will do for now. I hope I can get a simplified way of absorbing EFIS data into normalized performance charts and document it for others. When I ask local builders what they did, I found that most never really did any real testing with actual numbers.
* Plane is a RV-6A with gear fairing and wheel pants. Unmodified 180 HP O-360-A1A and 83 inch pitch Sensenich prop.
* Hope the chart comes out OK, it's a Photobucket replacement test.
Raw data for chart - first 3 columns straight out of the EFIS
These are the numbers from my Tiger POH. ROC is divided by 10 just to fit and use one chart scale. Definitely stright lines with std. day altitude. The red line is speed for best ROC -
If we have a good EFIS - my remarks are for a Skyview system, but I assume the competitors are similar - data entry is made simple, with more variables collected than you know what to do with.
Nice graphs can be made with a free subscription to savvyanalysis.com. So I was thinking can all of this data be extracted and normalized into a POH for your plane?
After examining the performance data from my certified Tiger POH I have extracted some data constants. I hope simple data analysis and conversion with Excel will do the trick.
Need confirmation from any aerodynamics experts on stuff below.
1. Taking the climb rates from the POH I extracted a straight line that gave a -6.422% drop in climb rate for each 1,000 ft of std day.
Q. I assume that if I convert my flight test altitudes to a Density Altitude this constant will remain the same. Is that correct?
DA has been high during my testing so far, and these individual climb rates were taken at various speeds at DAs ranging from 5,500 to 15,000 with most at 8000-9000. The aircraft weight as not been corrected by are for pilot and about 3/4 fuel.
The curve seems reasonable and sort of shows my 83 inch pitch Sensenich is probably a climb prop.
The confusion I had extracting data from the Tiger POH was that the IAS for max. climb rate changes by std day altitude. The factor was -1.282% per 1000 ft.
Q. Does that make sense? I thought DA would correct for this and IAS remain constant. If not, how do I apply this correction factor to the above data?
More questions to come, but that will do for now. I hope I can get a simplified way of absorbing EFIS data into normalized performance charts and document it for others. When I ask local builders what they did, I found that most never really did any real testing with actual numbers.
* Plane is a RV-6A with gear fairing and wheel pants. Unmodified 180 HP O-360-A1A and 83 inch pitch Sensenich prop.
* Hope the chart comes out OK, it's a Photobucket replacement test.
Raw data for chart - first 3 columns straight out of the EFIS
These are the numbers from my Tiger POH. ROC is divided by 10 just to fit and use one chart scale. Definitely stright lines with std. day altitude. The red line is speed for best ROC -
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