[Music] [Music] makkya helicopter lessons in ten minutes less I'm Jakob and this videos topic covers the different methods we have for measuring how fast an aircraft travels through the year now the most common terms that pilots use today are indicated calibrated and true airspeed in this video I'll break down each one hopefully help alleviate any kind of confusion between them and help to set a basis for where they come from so let's get started now the most basic way to measure airspeed is going to be the difference in pressure between a pitot tube and a static port this is going to give us an indicated airspeed and by indicated airspeed you'll usually see that abbreviated as IAS this like I said is a difference in pressure so it works by comparing a ram air pressure entering a pitot tube and comparing it to a static pressure measured by a static board so as you've looked at helicopters before usually towards the nose of a helicopter you can have a tube either maybe hanging below a weapon or below a wing or on a wing on a nose something like that you're gonna have a a tube that measures the ram air it's oriented towards the nose the helicopter also at another point in the helicopter you're gonna have more airplane that is you're gonna have static ports and these are just going to be little spots that have usually a ring with some dots in it that are helping are these these set kind of a baseline that they set the they measure the static pressure of the ambient air around so what happens for indicated airspeed is that seeing the difference in between these two so what happens is in between both of these two you're gonna have a gauge which is going to be a an airspeed indicator and that airspeed indicator is saying okay we have this much difference in between the static pressure and this ram air pressure it moves a needle a certain bit and this is given your reading for an indicated airspeed now this is a mechanical instrument that registers the difference on the face of this this gauge here but because it's purely mechanical based on pressure it's subject to air and therefore indicated airspeed is going to be regarded as kind of the least accurate of the ones that we have of the ones here for men during air speed and because of the airs measuring these measuring air speed it can cause quite a drastic difference in your navigation if you're doing potentially long distance flights using dead reckoning so what happens as many manufacturers will provide corrective corrective charts to to help get this this air speed a little bit more accurate for the pilot so the charts account for errors and convert an indicated air speed into a new more accurate form of air speed called calibrated airspeed calibrated usually abbreviated CI yes calibrated airspeed these torts are just based off of flight testing and Corrections for the known errors that are in the instruments the charts are empirical and just as simple as identifying where you're indicated airspeed is and converting it to calibrated airspeed so you'll usually see charts like this with calibrated airspeed on one side indicated airspeed on another side with a longer went through it and you just find whatever speed indicated intersect the line and come over and that's gonna give your calibrated airspeed now it speeds that helicopters fly this difference may only be just a few knots but for faster aircraft or if you're covering long distances on an old-fashioned cross-country VFR flight these subtle differences in airspeed can make a significant difference for you so what happens now is with your calibrated airspeed your airspeed can still be kind of fond tuned even more accurately and it can potentially be horrendously off depending on what kind of environment you're flying in and that's because unfortunately air doesn't have the same density and temperature everywhere you go so to take this this these types of air speeds to the next level we'll take it to our third type which is going to be true airspeed abbreviated as TAS so what what it's doing here is just taking your calibrated airspeed and you're gonna adjust this for temperature and pressure so a true airspeed is the true velocity of the aircraft relative to the atmosphere around it and keep in mind that as a standard sea level condition our calibrated airspeed is to equal career speed but if you're looking at extremes such as operating in the mountains or high altitude stuff like that you're gonna have some deviations so let's take a look at a just an example just to to outline that let's imagine you're flying it stated ten thousand feet the temperature up there is your degrees Celsius and let's just say you're flying along at a nice comfortable seventy five knots indicated air speed alright so you do your calibrated airspeed conversion based on your manufacturer's charts and it turns out that seventy five knots indicated air speed is actually about eighty knots calibrated airspeed all right so you know you get a little bit of an extra a few knots there but you're actually traveling a little bit faster than you then your instruments are telling you here and that's because of the the air density being so much less the higher altitude you are so you can calculate this usually with an e6b or sometimes your helicopter will do it for you but what I'm looking at is I entered the temperature and the altitude so zero I want to put that on the ten for ten thousand feet and then I'm reading the inner loop for calibrated airspeed of eighty that gives us a true airspeed of ninety four here on the outside ring so I did zero two zero degrees ten thousand feet eighty knots from my calibrated to the outside ring gives me my true of 94 knots so despite my gauge telling me I'm going 75 knots in all actuality going ninety-four knots this is a nineteen point difference from your indicated airspeed a pretty significant difference especially if you're trying to navigate based on time distance heading now the reason for this this drastic difference is because of the air is thinner and the dynamic pressure is less for the same speed and when you get into these higher altitudes so this means that if you maintain the same true airspeed and climb an altitude that indicated airspeed is going to tick down less and less and less and less because there's just less air molecules in the air but you are in fact traveling ninety four knots true airspeed at ten thousand feet not your seventy five knots that you're getting as an indication in the cockpit so it's kind of important to know because you're gonna have subtle differences and your navigation and whatnot but simply put your true airspeed is going to be your real airspeed and may not be what's shown on your airspeed indicator now some of the the newer helicopters like I was saying before they can calculate it for you based on their instrument packages some people have add-ons to their older cockpits that can modify they're calibrated to it true about putting in the pressure and temperature and still some people fly helicopters that don't have any of this and they just have to rely on a nice old b6 B or some planning on the ground before you do you even go and fly whichever method you use as fun as long as it's accurate but I do believe it's important to understand why there is a difference in between these air speeds and what causes that so you can know whether or not you shouldn't maybe recalculate or who readjust your plans so if you're new to the helicopter community and you still don't have an e6b i'd highly recommend getting one does a lot of stuff not just calculation for true airspeed but also fuel computations and whatnot doesn't require batteries it fits easily in a flight bag and can really help you out in a pinch if you got to do some some quick math but that wraps up this video we talked about the indicated airspeed calibrated airspeed and true airspeed and how they're accuracies can differ and generally how they build upon each other you need you get your calibrated airspeed based on the charts for manufacture and comparing that to your indicated airspeed and you modify your calibrated airspeed with the pressure and temperature to get your true airspeed but if you enjoy the video make sure you hit like and subscribe and below also be sure to leave any feedback you have in the comment section below but ultimately thanks for watching I'm Jacob and this has been helicopter lessons in 10 minutes or less as always say flying [Music] [Music]