Finley Atherton
Well Known Member
Thanks Kevin and Hevansrv 7A for your comments.
Why 70 kts? My reasoning may be wrong but for these two flights I was simply trying to determine the effects of the stopped prop and throttle setting rather than get accurate quantitative data at best glide speed. If the stopped prop and open throttle reduce the rate of descent at 70 kts, then I presume the EFFECT would be the same at my 80 kts best glide. I was also trying to cram a lot into each of these glides and I would have had less time at the best glide speed rather than the 70 kt min sink speed.
Finally, I have usually found on previous glides that it is harder to peg the speed as the speed increases, so I thought a slower speed would be more likely to give accurate results.
Kevin,
It would certainly have been preferable to do the glides as you describe. On the day when I did the glides to determine best glide speed (post 81) I did multiple flights in same direction in the same block of air using a stop watch. I picked a day where the air was smooth and the winds light. Not perfect, but I did find that I was able to reasonably hold the set speed on each glide so I think changing winds were not a significant factor. As for the more recent two glides I again picked a day with smooth air and light winds, also my comments to Hevansrv 7A may address partly what you have said.
These glides were done with the engine dead which is not a natural state of affairs for the average novice pilot like me so I tend to be reluctant to do the multiple flights in different directions to get the most accurate figures. The engine is also a consideration. Even though I did what I could to reduce the likelihood of shock cooling to the engine I tried to minimize the number of power off glides to be kind to my engine.
Your comments are greatly appreciated and I may try to incorporate your suggestions if I do this again.
Fin
9A
Why 70 kts? My reasoning may be wrong but for these two flights I was simply trying to determine the effects of the stopped prop and throttle setting rather than get accurate quantitative data at best glide speed. If the stopped prop and open throttle reduce the rate of descent at 70 kts, then I presume the EFFECT would be the same at my 80 kts best glide. I was also trying to cram a lot into each of these glides and I would have had less time at the best glide speed rather than the 70 kt min sink speed.
Finally, I have usually found on previous glides that it is harder to peg the speed as the speed increases, so I thought a slower speed would be more likely to give accurate results.
Kevin,
It would certainly have been preferable to do the glides as you describe. On the day when I did the glides to determine best glide speed (post 81) I did multiple flights in same direction in the same block of air using a stop watch. I picked a day where the air was smooth and the winds light. Not perfect, but I did find that I was able to reasonably hold the set speed on each glide so I think changing winds were not a significant factor. As for the more recent two glides I again picked a day with smooth air and light winds, also my comments to Hevansrv 7A may address partly what you have said.
These glides were done with the engine dead which is not a natural state of affairs for the average novice pilot like me so I tend to be reluctant to do the multiple flights in different directions to get the most accurate figures. The engine is also a consideration. Even though I did what I could to reduce the likelihood of shock cooling to the engine I tried to minimize the number of power off glides to be kind to my engine.
Your comments are greatly appreciated and I may try to incorporate your suggestions if I do this again.
Fin
9A
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