So in a glide, flying at the best glide speed, will you be pitching the nose up (nose points above the horizon) or pitching the nose down (nose points below the horizon) or does it depend?
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$\begingroup$ In practice you will fly rarely with the best glide speed. In thermics you will fly with the speed of lest decend or a little below to stay as long as possible in the upwind. Between thermics you will fly faster then the best glide speed since between thermics the air descends an you want to pass that fast. How much you exceed the best gliding speed depends on the strength of the thermics that in turn determines the strength of the descending air inbetween... see: en.wikipedia.org/wiki/Speed_to_fly $\endgroup$– Timothy TruckleAug 15 at 9:33
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$\begingroup$ Are you asking about the initial change in the nose attitude required to establish steady state flight at whatever best glide speed is? or the nose attitude required to maintain that steady state speed once established? In either case, there are many factors involved. The aircraft itself being the biggest one. $\endgroup$– Charles BretanaAug 15 at 13:06
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You pitch at whatever angle and attitude is required to maintain your desired speed. That's why it's called best glide speed, not best glide angle.
Having said that, unless you were already descending, it's going to end up with the nose being at or below the horizon since, well, you're gliding...
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2$\begingroup$ Not so, in a high performance swept wing jet, (most fighter aircraft, or Concorde, for example), the AOA at best glide speed is greater than the flight path glide angle, and the nose will be above the horizon... $\endgroup$ Aug 15 at 13:09
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$\begingroup$ @CharlesBretana Right, and what do you think the chances are that the OP is flying any of those types? $\endgroup$– CloudAug 15 at 13:19
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2$\begingroup$ The example given (high performance swept wing, is just the extreme. The point made ( that AOA and glide angle are the determinants), does not only apply there. Using another more common example, many GA aircraft in a no-flap configuration, have the nose above the horizon in a glide. $\endgroup$ Aug 15 at 13:33
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1$\begingroup$ Your comment is wrong because you conflate nose or pitch attitude with flight path angle. Just because, as you comment ("since, well, you're gliding..."), doesn't mean that the nose pitch attitude has to be below the horizon. Using yet another (less common) example, in extremely high performance gliders, for example, where the glide ratios are very high (some are 70:1), even a very small AOA will put the nose above the horizon. $\endgroup$ Aug 15 at 13:36
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$\begingroup$ Surely the key point is not the nose, but the wing itself? $\endgroup$– MikeBAug 15 at 13:42
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Are you asking about the initial change in the nose attitude required to establish steady state flight at whatever best glide speed is? or the nose attitude required to maintain that steady state speed once established? In either case, there are many factors involved. The aircraft itself being the biggest one.
If you are asking about the initial pitch required, then there are so many variables, that there is no clear answer....
But if you are asking about the steady state situation, once you have established it, then in general, the answer depends on the difference between the flight path glide angle, at best glide speed, and the Angle of Attack (AOA) required to hold that glide angle. If the AOA is greater than the glide angle, then the nose will be above the horizon, if it is less....
