5 ms·
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 d
by kqr 5y ago
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 important as they are. Instead, pilots have to infer them by combining readings from multiple other sources.
[1]: https://www.av8n.com/how/#contents https://www.av8n.com/how/#contents
- p_l 5y agoFortunately, on gliders where specific knowledge of airflow over your plane is very important, yaw string become pretty much standard equipment, traditionally applied with electric tape. Though imagine rewatching after years scenes from The Final Countdown, and noticing that the F-14 have your well known yaw strings installed in very familiar way (and finding out later that it was unauthorized, but very common, modification known to increase accuracy heavily).
- na85 5y agoAircraft 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.
- gorgoiler 5y agoAlas, this is typical of these head-in-the-clouds engineering types. More concerned with the technical details about keeping their precious machinery working than anything practical like am I going to get to Malaga in time for dinner. joke
- H8crilA 5y agoThe speedometer shows IAS which is way more informative of what's happening to the aircraft than GS or TAS. IAS measures "the amount of air that hits the wings". As to altitude there isn't a single always applicable definition of "altitude" hence pilots have to adjust it based on their current task, there simply isn't a way around that. You could try to always use "true altitude" in WGS-84 or something, but that's far more complex than a simple pressure altimeter. For example it generally cannot be done without external inputs, such as very accurate pressure maps or gps-like navigation aids. More complex = more failure opportunity.
- na85 5y agoI know. I'm an aerospace engineer. I still think it's fun(ny) to muse about these things.
- perilunar 5y agoNot silly at all but quite practical. How do you propose they could have easily measured true airspeed and true altitude before GPS?
- namibj 5y agoTAS doesn't need GPS. Ground speed does, but for (near) transonic operation, IAS alone isn't sufficient. A Mach meter can be enough of an addition, though.
- travisjungroth 5y agoGPS doesn’t help you with TAS at all. TAS indicators existed before GPS. They take IAS and do the same calculation you would to get TAS.
- na85 5y agoWith a rock tied to the end of a rope of course.
- FL410 5y agoMany 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.
- kqr 5y agoAccording 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-airplane https://www.av8n.com/how/htm/motion.html#sec-centrifugal-air...)
- H8crilA 5y agoIt happens to be the same thing, almost always [barring performing aerobatic maneuvers which definitely require special training].
- jtbayly 5y agoOr, according to the article, if you're in a twin engine plane with one engine out.
- namibj 5y agoOne such maneuver might be a deliberate sideslip during final approach, in particular the transition to no sideslip right after touchdown (unless all wheels steer, which is rare (the B-52 is a notable example)). I'm not too well versed in the details, though.
- upofadown 5y ago>Many gliders and helicopters have yaw strings. Airplanes don’t, because they usually have a slip/skid indicator which tells you the same thing. Comment from a glider instructor of my acquaintance: Yeah, and that big fan in front of the yawstring doesn't help. Might explain why yawstrings are more common in the twin engine case...
- ramesh31 5y ago>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. The slip indicator, which replaces a yaw string in modern aircraft, is part of the standard avionics 6 pack.