I have never satisfactorily determined the "Best Glide" speed for my F1 EVO Rocket. I have now done a few flights trying to pinpoint this, and while I think I need to change my process a bit in order to get more accurate, I have discovered a weird anomaly and I wonder if others have seen something similar. The following graph shows the data points I have determined in 3 different flights on different days. The thing I think is weird is that every flight shows that at 105 knots the glide ratio is worse than the preceding or subsequent speed.
Anybody have an explanation for such a result?
The method I have been using: Determine the number of seconds it takes to glide from 3500' to 3000' at a constant IAS (+-1 knot). I get this from the data log of my G3X. I then convert the speed to "feet/minute forward" (knots * 101.269) and descent to "feet/minute vertical" (60/(seconds * 2) * 1000). Dividing feet/minute forward by feet/minute vertical provides the glide ratio. The speed with the best glide ratio is the best glide speed.
The problem I have with this method is that I need a more granular measure of time, or I need to increase the glide distance to 1500 or 2000 feet. However I don't believe making these changes will impact the seemingly repeatable event that shows 105 knots having a poor glide ratio.
I also understand that flying on different days with different weights, temperatures and air densities will also give differing results, so I am not unduly concerned that each days flight has some differences.
Anybody have an explanation for such a result?
The method I have been using: Determine the number of seconds it takes to glide from 3500' to 3000' at a constant IAS (+-1 knot). I get this from the data log of my G3X. I then convert the speed to "feet/minute forward" (knots * 101.269) and descent to "feet/minute vertical" (60/(seconds * 2) * 1000). Dividing feet/minute forward by feet/minute vertical provides the glide ratio. The speed with the best glide ratio is the best glide speed.
The problem I have with this method is that I need a more granular measure of time, or I need to increase the glide distance to 1500 or 2000 feet. However I don't believe making these changes will impact the seemingly repeatable event that shows 105 knots having a poor glide ratio.
I also understand that flying on different days with different weights, temperatures and air densities will also give differing results, so I am not unduly concerned that each days flight has some differences.