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I remember this one glider pilot who duplicated all instruments in his glider, so that he would never fail a glider competition day for technical reasons. And yes, he also had two yaw strings, this guy was r-e-a-d-y :)
I remember this one glider pilot who duplicated all instruments in his glider, so that he would never fail a glider competition day for technical reasons. And yes, he also had two yaw strings, this guy was r-e-a-d-y :)
There is an argument that having 2 short yaw strings, one behind the other, is better in terms of human factors. You have a stronger indication of the correct state in your peripheral vision. The alignment of two lines is a fairly strong indication in vision. * https://www.youtube.com/watch?v=OR9zJwcGxoQ
But that's no why that particular guy had two strings :). He just wanted to be double sure that his aircraft will perform at all times. I think he even had 3 certified flight recorders since misconfiguration or other failure of the certified flight recorder is the most common technical problem during a competition flight (you might not be aware that this little box is faulty until after you land). Actually quite a few "serious" glider pilots carry a second flight recorder.
Reminds me of tell-tales on sailboats which are similar bits of string attached to sails which give feedback about how you might need to adjust your sails to keep the wind moving over them smoothly.
Earlier quoted context omitted.
Many gliders and helicopters have yaw strings. Airplanes don’t, because they usually have a slip/skid indicator which tells you the same thing. But once you’ve been flying a while, you don’t really need it, you can feel it.
According to Denker, the inclinometer ball doesn't actually measure yaw against wind, but something different that can sorta maybe in most situations be interpreted as yaw against wind. (Specifically, it measures the combination of gravity and centrifugal forces on a motion-constrained mass, from what I can tell: https://www.av8n.com/how/htm/motion.html#sec-centrifugal-air... )
I remember this one glider pilot who duplicated all instruments in his glider, so that he would never fail a glider competition day for technical reasons. And yes, he also had two yaw strings, this guy was r-e-a-d-y :)
This is one of multiple instruments that, according to the author of See How It Flies[1] indicate important readings to the pilot, but don't exist at all in a default airplane. A couple of other examples are an adjustable indication on the windscreen of where "straight in front of you" is, as well as an angle of attack indicator. Angle of attack, pitch angle, and yaw commonly don't have their own indicators, as impor…
Aircraft are kind of silly in many ways. The default speedometer doesn't actually tell you how fast you're going, and the default altimeter doesn't actually tell you how high you are.
Earlier quoted context omitted.
According to Denker, the inclinometer ball doesn't actually measure yaw against wind, but something different that can sorta maybe in most situations be interpreted as yaw against wind. (Specifically, it measures the combination of gravity and centrifugal forces on a motion-constrained mass, from what I can tell: https://www.av8n.com/how/htm/motion.html#sec-centrifugal-air... )
It happens to be the same thing, almost always [barring performing aerobatic maneuvers which definitely require special training].
I'm not too well versed in the details, though.
Earlier quoted context omitted.
Aircraft are kind of silly in many ways. The default speedometer doesn't actually tell you how fast you're going, and the default altimeter doesn't actually tell you how high you are.
Not silly at all but quite practical. How do you propose they could have easily measured true airspeed and true altitude before GPS?
it's funny that simple mechanical things are so useful on planes. Angle of attack is just a weight on a horizontal hinge, airspeed is done with basically a mass airflow sensor - that is, you heat some mass next to a thermocouple and see how long it takes the mass to cool down. Obviously non-MEMS gyroscopes count, too, as well as non-MEMS compasses. and this, just a bit of yarn on a halyard. sometimes with a cone on t…
On gliders, the airspeed indicator is even simpler - just a pitot tube connected to a (very sensitive) pressure gauge. The variometer (a vertical speed indicator) uses an internal air reservoir and a calibrated restriction to derive rate of climb or descent. So, all the main instruments (altimeter, airspeed, vario) are worked by atmospheric pressure, no batteries needed.
The first major modification was the total energy variometer, which takes account of the fact that you can trade speed for altitude and vice-versa. It gives a figure (expressed as an equivalent rate of climb) that corresponds to whether the sum of your potential and kinetic energy is increasing or decreasing. This is particularly useful in rough air, where, with a simple variometer, it is difficult to center on the strongest updraft.
As the performance of gliders improved, and the speed for optimal glide angle diverged from that for minimum sink rate, it became useful to know the vertical speed of the airmass, as, when flying fast, your descent rate is quite high even if the air is rising. Netto / airmass variometers compensate for the still-air rate of descent you would have at the current airspeed. Relative netto variometers show the difference between this and the minimum sink rate.
All of this can be achieved by clever plumbing, though electrical instruments can have less lag, and potentially adjust for flap setting and ballast weight. One orthogonal development that requires electricity is the audio variometer, which emits a sound of varying pitch to indicate rate of climb or descent - an important safety issue, as you can monitor this datum while looking outside of the cockpit.
Another thing that variometers are usually equipped with is the speed-to-fly ring, invented by Paul McCready of 'Gossamer Albatross' fame. It gives a useful (even though imprecise, on account of the parameters that have to be estimated) indication of the optimal speed to be flying at for the current variometer reading.
As in the case of indicated vs. true airspeed, it is important to understand what you need the information for.
This is one of multiple instruments that, according to the author of See How It Flies[1] indicate important readings to the pilot, but don't exist at all in a default airplane. A couple of other examples are an adjustable indication on the windscreen of where "straight in front of you" is, as well as an angle of attack indicator. Angle of attack, pitch angle, and yaw commonly don't have their own indicators, as impor…
The slip indicator, which replaces a yaw string in modern aircraft, is part of the standard avionics 6 pack.