It's not magnetic compass, turn coordinator, stopwatch, wind meter, VVI, and airspeed indicator. I want to know what is the first flight instrument.
8$\begingroup$ That would probably be the engine rpm indicator. $\endgroup$– minsNov 1, 2017 at 17:18
3$\begingroup$ I'd say pilot's brain and senses, able to map the terrain, feel altitude, temperature, speed, bank angle, distances ( eyes telemetry ) $\endgroup$– jkztdNov 1, 2017 at 17:18
4$\begingroup$ According to this essay Orville Wright held a mechanical Anemometer and a stopwatch. $\endgroup$– CGCampbellNov 1, 2017 at 17:19
1$\begingroup$ tachometer or watch $\endgroup$– Steve KuoNov 1, 2017 at 17:40
7$\begingroup$ I'd say a binary thermometer. As in does wax melt at this distance to the sun or not. Ikaros used one inefficiently. $\endgroup$– BentNov 2, 2017 at 19:24
It's the yaw string:
The yaw string dates from the earliest days of aviation, and actually was the first flight instrument.
3$\begingroup$ Can you integrate some information from the article into your answer? What's a yaw string? $\endgroup$– isanaeNov 2, 2017 at 16:29
4$\begingroup$ How did they use a Yaw string on planes without canopies? $\endgroup$ Nov 2, 2017 at 16:57
$\begingroup$ @BruceWayne Slingsby T21 has no canopy and often has a yaw string tied to the pitot tube, which emerges from the top of the nose infront of the cockpit. Clearly, a pitot tube services an ASI, so this is perhaps a bad example! $\endgroup$ Nov 2, 2017 at 17:30
$\begingroup$ LOL biplanes don't have yaw strings. $\endgroup$ Nov 2, 2017 at 19:12
2$\begingroup$ @BruceWayne: you tie the string to anything that protrudes. $\endgroup$ Nov 3, 2017 at 4:43
The Wright Flyer, arguably the first controllable aircraft, had three instruments:
A stopwatch to measure air time.
A crude tachometer to gauge engine speed
And an anemometer, to make an estimate of distance traveled by measuring airflow.
5$\begingroup$ The question does not specify powered flight, which this answer assumes. $\endgroup$ Nov 2, 2017 at 18:40
$\begingroup$ @ErinAnne The question title does say "airplane," not just "aircraft," so that narrows it down quite a bit in regards to things that existed prior to the Wright flyers. It leaves only gliders and powered airplanes in consideration. $\endgroup$– reirabNov 3, 2017 at 2:59
$\begingroup$ I'm pretty sure it had a yaw string as well-- as did several of the Wright gliders that preceded it. $\endgroup$ May 3, 2020 at 19:53
I believe the correct answer (and the answer that you looking for) would be the forerunner of the of an artificial horizon, the yaw string. The tendency of airplanes (particularly pioneer aircraft) to roll needed to correct in a timely manner, and the visual earth horizon reference was not an effective means of detecting slip or skid in the necessary timely manner. Consisting of a suspended short piece string or yarn, often weighted the bottom give the pilot a quick measure of the side slip angle of the craft.
However, the magnetic compass in my opinion would be the first true instrument. Of the seven standard flight instruments, the altimeter, attitude indicator (artificial horizon), airspeed indicator, magnetic compass, heading indicator, turn and band indicator, and vertical speed indicator, the magnetic compass was not only an existing instrument, but would have become a natural necessity as flying evolved from the day-light, good weather over ground with recognizable landmarks, to night time, over water or monotonous terrain, or limited visibility, etc.
Early flight in conditions that disallowed landmark and horizon earth reference often used dead reckoning as a means of navigation. The ability to maintain a constant and correct direction of travel is essential to dead reckoning. A magnetic compass would have been the logical first step.
However, the earth magnetic fluctuations, mistaken speed of travel, and travel heading deviation (the sidewards travel of a vessel as the result of forces (such as wind, currents, etc.) makes dead reckoning as means navigation by any means of transportation, well, dicey. Consider 50 mile due south flight over water with no visual references, if a easterly cross wind deviates the flight path one half mile laterally for every ten miles of flights, then, even with a correct speed in relation to ground, the pilot could of the mark by two and half miles. Thus many other flight instruments had to be developed to bring aviation to where it's at today.
Known as Gyro, Lawrence B. Sperry, a well known for many innovative flight instruments he constantly conceived, developed and personally tested. Gyro was one the first to fly at night, regularly army night flights in 1916. Todays modern aircraft still equipped with the basic flight instruments the Sperry developed.