Michael Hall posted today:What do you mean by impracticality? If you are flying from point A to point B your “technique” is to fly directly there, accounting for wind. If the wind were zero, or perfectly on a line between the two it actually gets easier because there is no drift angle needing adjustment.

- the point is that the actual winds are not easy to precisely know, with the precision that would be needed to meaningfully help estimate the sideslip angle. (Obviously it depends on the equipment in the aircraft -- but if we assume the aircraft is equipped w/ technology such that the actual winds can be precisely known, why not assume a sideslip vane as well?)

In my own flying, although I have a GPS-based procedure for estimating the wind direction, my best guess of the actual wind direction occurs after I run the saved track log through "See You" after landing.

MH answered with a comment saying (essentially) how with modern technology how easy it is to fly a heading such that the resulting ground track is aimed (nearly?) straight toward objective. Obviously that's true, I do that routinely even flying with hand-held GPS in sailplane.

But that's not the same as knowing the exact wind direction well enough to come to a meaningful estimate of sideslip angle, using some technique based on putting either the aircraft heading, or the ground track, exactly into the wind.

There are many, many airplanes these days with GPS. (or tablet with mapping software) Whether or not the screen displays wind doesn't really matter, it's easy enough to follow the magenta line and in doing so, correct for the effects with no math or E6B tomfoolery. But I've never seen any plane with a sideslip vane. (unless that's yarn on a glider?) Taking out sideslip is what the balance ball is for.

What is a "meaningful" estimate of sideslip angle? Generally the goal should be zero, right?

@quietflyer, again I will quote from your answer: "Since we usually fly with zero sideslip as best we can, and experience no more particular tendency to slip when flying crosswise to the wind than any other time, your questions are pretty much moot as far as all practical flying and navigation is concerned."

So why then do we need/want to know the actual angle?

To give some further perspective, even the aircraft's exact heading is not necessarily known iwith great precision (say + or - 3 degrees) in many of the aircraft I fly. So-- being able to use a GPS to track directly toward goal, does not mean I can do some sort of procedure to accurately determine sideslip based on some sort of determination of the exact wind direction, and/or drift angle. So-- it's impractical.

Again, why do you care about actual sideslip angle at all if the goal is zero?

Center the ball, center the yarn, and carry on...

I'm having trouble keeping "track" of where this discussion is "heading". Your latest question seems to be one better directed toward the O.P..

Ha! Good pun...

Fair enough then, it seems we agree that the actual angle is immaterial from a practical standpoint.

Now, these vanes need to be calibrated as well, since the measured angle will be influenced by the aerodynamic flow round the fuselage, and thus needs correction. This could be done by flying straight downwind and calculate the side slip angle as the difference between heading and track. Although I believe it is more common to use CFD for the calibration.

See aviation.stackexchange.com/questions/78155/…

@DeltaLima, understood. Presumably though if the OP were involved with flight test they would know that already...

@MichaelHall maybe, but we all started to learn from zero.

Yes, but when someone asks for a sip and you blast them with a firehose...