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Single Propeller load asymmetry in turns

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Single Propeller load asymmetry in turns

Old 17th Apr 2019, 00:04
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Single Propeller load asymmetry in turns

Does this have a formula, and what is the current Flight Physics consensus of the effect of this on turns?

G.
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Old 17th Apr 2019, 01:27
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I would think a propeller would be completely happy with a coordinated turn. Not so happy with skidding or slipping flight.
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Old 17th Apr 2019, 18:39
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Gaston,for a bit of light reading ,try;;`apps.dtic.mil/dtic/tr/fulltext/u2/776998.pdf`....sorry can`t do a link..
or; `Summary of propeller design procedures and data`.Vol 111(3),by Edward Sand,Nov`73, AD-776-998.
by National Technical Information Services...
I can guarantee you will sleep easily...
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Old 17th Apr 2019, 22:21
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Propellers are almost always at some incidence angle from horizontal (equal to the angle of attack +/- any offset between the crankshaft and longitudinal centerline), so why would a bit of yaw bother them?
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Old 27th Apr 2019, 06:11
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A turn is not angled airflow. It is curving airflow. The airflow is slower on the inside turn part of the prop, which is not the case in a yaw (even for the split second the yaw is generated, because it could be that it is mostly the outside yaw prop portion that is accelerated, whereas in a turn, the inside prop portion must decelerate). This undoubtedly means a constant increase of the vacuum (in front of the blades) on the inside turn disc portion, which implies some kind of off-centered increase in trust that is nullified by the speed cost of the turn.

The reason you can get away with the notion of angled airflow on a wing (in a real curving turn) is because the height of the interaction is very narrow. This is far from the case with the height of a large prop, which is easily 10 to 14 times greater... Unlike a wing, any curvature implies a significant difference in airflow speed over such a broad height...

They cannot replicate this in a wind tunnnel, for obvious reasons... This is why I was asking what is the current consensus on this.

Gaston

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Old 14th May 2019, 15:07
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For an aircraft travelling at 200 knots in a 6 degree per second (steep) turn, and with a propeller radius of 1 metre (big), the difference in airspeed at opposite propeller tips will be maximum 0.4 knots. With incident airflow of 200 knots I find it hard to believe that can have an affect worth worrying about. Certainly any asymmetry in presenting the prop to the airflow (unbalanced turn) will be a greater issue.
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