29.8k ChiChiWerx Comments

  • Ukrainian Flight 752 Crashes in Iran, 176 deaths 4.3 years ago

    @Vidal99977 I fly the 737 for a major US airline and an engine failure, as related by Iranian authorities, does not bring down an airliner in flames. I suffered an engine failure (compressor stall), flames shot out the back (as related by the passengers in back). We simply secured the engine and proceeded to landing. Even SWA1380, which suffered an uncontained engine failure, didn’t burn and fall out of the sky. And by the way, the engine manufacturer isn’t even Boeing, it’s CFM, who builds the CFM56 engine which powers the 737NG, so you can’t even blame that on Boeing, even IF true. Gimme a break. The Iranians better have a rock solid explanation plus release the black boxes for independent analysis before I believe their propaganda.

    +3
  • Cheng du JF17(FC-1) Lightning 4.3 years ago

    I could write 100 pages on my assessment for this build...bottom line it’s impressive given the builder’s level. The highlights are the smooth flight model, the overall shape of the jet and the cockpit...especially because the builder managed to build a full cockpit without sacrificing the rest of the plane. The paneling is nice and there’s clearly been a lot of work here. Next time I would suggest more drag reduction because it accelerates a bit too swiftly and it’s still too slow down low. And I must say, the JF-17 is attractive for a modern jet, but it’s not the most beautiful airplane out there ;)...that honor would go to the F-80, IMHO. Nice work!

    +3
  • RamboJutter "Trudence" MKII 2.3 4.4 years ago

    This thing is ridonculous...those two 19 year old M1 crewmen I watched barreling across the tank practice area at Ft Carson at more than 60 mph—they reminded me of the two dudes who took Cameron’s Ferrari for a joyride in Ferris Bueller’s Day Off—would love this thing!

    +3
  • RamboJutter F4 MKIV 2.1 4.6 years ago

    F4 Test Report by Sir Thomas V. Brentprop, IV, DSO, DFC...Certainly a fast ship, acceleration is exelplary, much as a brace of hunting dogs pursuing a hare or fox on a fine hunting day! As stable and solid as one of the many majestic castles dotting the bucolic English countryside. The high speed makes this one a handful on a torp run...one has to remain precisely aware of the hazards accompanying the pursuit, otherwise he will find himself in the drink! Landing on the pitching deck of a flattop is a touchy affair...final is stable and well controlled at a stately 140 mph and approximately 20% power, fully configured, of course... the nose up attitude makes it difficult to spot the deck, old boy, but this is a common difficulty on shipborne prop fighters and one not unfamiliar to this old Seafire ace! In spite of all that, landing was a breeze, well done! Huzzah!

    +3
  • MOOSE Tactical Conveyor [GP-1] 4.7 years ago

    Well, I really like the effort shown on the HUD. It’s a bit faster than it ought to be, you might have dialed back the engine power and this would have also given it more realistic acceleration. It is a fictional build, though, so you have a bit more leeway than with a replica.

    +3
  • General Dynamics F-111C Aardvark 4.8 years ago

    @ChisP no, you’re thinking of the F-111B, which was the shipboard version of the F-111, it’s distinguishable in that it had a blunter nose. That airplane was developed at the insistence of Secretary of Defense Robert McNamara, who had run Ford Motor Company prior to his appointment as SecDef. McNamara insisted that the Department of Defense would save a lot of money if they used common airframes between the USAF and the Navy. As the AF was trying to field the 111 as it’s next interdictor bomber, McNamara insisted it be developed into the Navy’s F-4 replacement...for the role of fleet defense—essentially interception and air-to-air combat. The Aardvark is many things...but it’s not, and was never meant to be, a fighter...which the Navy discovered upon evaluation. I think 2 or 3 were built. When told that the 111 was thrust deficient as an air-to-air fighter, McNamara asked “well, how much more thrust does it need???” The Chief Of Naval Operations at the time replied, “There isn’t enough thrust in all Christendom to make a Navy fighter out of that airplane!” The B model was canceled shortly thereafter and the F-14 was developed as the Navy’s fleet defense fighter. The Air Force version, however, went on to fly a long and distinguished career, as an interdictor bomber, including in Vietnam and Gulf War I.

    +3
  • An issue with SimplePlanes Discords 4.9 years ago

    I agree the Holocaust is no joking matter, but this would be better served in the forum where you read the offending comments. Last I checked, SP forums are fairly well behaved and managed. If I’m wrong, please show me where and I’ll be sure to call out any stupid comments.

    +3
  • [CLOSED] Dogfight tournament! [25 upvote prize] (WW2 Fiction & Replica) 5.0 years ago

    Recommend you relax your limitation on four guns...why?: The P-47 had eight guns, the P-51 had six guns (most versions), the P-38 had five guns, the P-40 had six guns (most versions), the Hurricane had eight guns (albeit smaller caliber than the U.S. planes), the Spitfire had up to eight guns, the Me-109 has up to five guns in later versions, the FW-190 had six guns, the Wildcat, Hellcat and Corsair all had six guns. Of the major combatants, only the Japanese and Italian fighters normally had fewer than six guns, normally to save weight and maximize maneuverability.

    +3
  • F-100 super sabre 5.1 years ago

    Well, the shape is pretty good. I like some of the details, certainly and you have a good eye for elements most builders miss (upsloping forward fuse, intake shape, gear details). It’s woefully underpowered...the real thing was supersonic (approx 760 mph at SL). Recommend using the more powerful engines—yes it would be “overpowered” as compared to the real thing...which may be what you were going for by using two smaller engines here. I think the J57 in the D model put out 16,000 lbs of thrust, but SP doesn’t yield the correct performance, so you might as well work around that and just use the bigger engines.

    +3
  • B-17G "Arf n' Arf" 5.2 years ago

    Don’t know why I hadn’t seen this before. Very moving story as well, very nice build.

    +3
  • Why the current system of our site is not fair. 5.2 years ago

    This and other posts like this amount to nothing but complaining. You guys need to give it a rest.

    +3
  • Henschel Hs 123A-1 'F' [Schl.]/LG2 5.3 years ago

    You realize you have skills. With a bit of input on your flight models, you’d have some of the best creations ever on the site. Do you have anyone fly your creations prior to posting?

    +3
  • The F-117 was never really a fighter 5.4 years ago

    It was a bomber...but the AF is in the habit of calling any single pilot fighter-sized jet a fighter. Even, officially, the A-10 is a “fighter” for required crew qualifications and organizational purposes. Every single A-10 unit is a fighter squadron, fighter group or fighter wing...not an attack unit in there at all.

    +3
  • Fokker Dr. 1 5.5 years ago

    Bravo, Bravo! This is beautiful, accurate in looks and performance both...best Dr.1 on the site!

    +3
  • approach glidepath indicator prototype 5.5 years ago

    Wish we had some sort of “instrumentation” tag for things like this, instead of just the more general “parts” tag.

    +3
  • Boeing B-50 D Superfortress 5.5 years ago

    Only 14 upvotes? Deserves a lot more...

    +3
  • F-15J JASDF ADTW 5.7 years ago

    Extremely pretty Eagle, nice details and well thought out. There are ways of making the acceleration more realistic, but for now, here’s a Spotlight for you nice work!

    +3
  • P-51 vs Spitfire 5.8 years ago

    @RailfanEthan are you talking about the F-94, I think it was, that spun in trying to shoot down a Po-2 in Korea? You are correct.

    +3
  • Trainer Challenge [CLOSED] 6.2 years ago

    So, this challenge intrigues me...unfortunately I don’t have the extra time to enter and present a worthy build. I do have one input, however. Considering your scoring of performance characteristics, I agree “does it fly like a trainer” is subjective and totally up to you. My input, having nearly 1000 hrs in the mighty T-37B Tweet and over 500 hrs in the T-38, just because a plane is a trainer doesn’t mean it’s not maneuverable. The ‘38 had a max roll rate in excess of 720 degrees per second, more than the F-16 and enough to earn an operational restriction prohibiting continuous aileron rolls. The Tweet could turn inside just about any airplane due to its thick wing, low speed and ability to pull more than 4 Gs. So, I would advise (unsolicited, of course) not to grade too harshly against a maneuverable entry (provided it’s not unrealistically so), but weigh more towards whether it’s “easy to fly, forgiving and absent adverse handling characteristics”. But, it is your challenge, just offering some input and sorry I can’t enter.

    +3
  • How do you make a rotator's input an activation group? 6.4 years ago

    In the builder view, with the rotator selected (highlighted), open up the menu (gear icon in the menu on the left side of the screen), go down to “Input Control”, then “Activation Group”. Click on activation group until you’ve selected the correct activation group (1 - 8).

    +3
  • ! DarkStar TOPGUN MAVERICK ! 4 months ago

    @ThePogKing yes.

    +2
  • F-112 Delta Spear 4 months ago

    Beautiful flight model. I’m jealous.

    +2
  • Northrop F-5E-3 Tiger II Aggressor 'PAK FA' one year ago

    @FalconDynamics it floats on landing and it has a distinct stall “break”. Sure the F-5 doesn’t use the NACA0009 airfoil, but the wing it does use is much closer in terms of drag and lift characteristics than any flat bottomed airfoil. Your build’s flight model is good, but it would have been closer to the real thing if you’d use the symmetric airfoil. How do I know? I have 500 instructor hours in the T-38, same family as the F-5, both flew very similarly and I swapped your build’s wing for the symmetric airfoil and I think it was more spot-on than before. And that’s from real life experience.

    +2
  • Simple MiG-21bis 1.2 years ago

    This is an exceptional build, the flight model is outstanding, reminds me of a couple of my builds. One of the only things I would have done differently would have been to use the symmetric airfoil, just like the RL jet, which would fix that float on landing. I could write more details, but overall, excellent, really, really excellent.

    +2
  • F-106A Delta Dart 1.3 years ago

    Cool bear, how’d you do it?

    +2
  • Me-262 "Schwalbe" 2.4 years ago

    Lots of great techniques here, on my favorites list!

    +2
  • [BUG???] Is TAS way off, their modeled Air Density that's way off, or is my understanding way off? 2.4 years ago

    No, you’re incorrect. And since I came up with the formula @edensk is quoting, let me explain: Mach varies based on temperature, NOT air density. The reason why Mach varies with altitude is that it generally gets colder with higher altitude, that’s why Mach 1 is achieved at a slower TAS at higher altitudes. And that’s why your very rough TAS/343 formula gets further and further off with altitude. But SP doesn’t have temperature incorporated, only altitude and airspeed, so Mach doesn’t vary correctly. But there’s a workaround I came up with: I assumed a standard day temp at S.L. (around 15 degrees Celsius), with a standard temperature decrease of 2 degrees C per 1,000 ft/330 meters. So, I simply modeled the TAS to Mach variation based on standard day temperatures with increasing altitude. For example: I know that it should be 10 degrees C colder at 5,000’ than it is at sea level and the Mach 1 TAS speed is proportionally slower. The conversion factor is .003937 per meter of altitude. There are a couple of problems with my formula: When you get to the Tropopause at around 50,000’ (again, the altitude varies with latitude, from 34,000’ (at the poles) to 56,000’ (equator), so I just used a mid-latitude height) temperature remains constant as you continue to climb. It then gets colder again as you leave the Tropo. That’s why I clamped the correction at 43 m/s…it’s good for a Mach calculation from sea level to around 60,000’ for a mid-latitude location. Two of the four major SP islands seem temperate, so I think that’s a fair assumption. The second issue is that it assumes standard day conditions/temperature…hardly ever the case IRL, where it’s most often colder or hotter, but again, had to model using assumed temperature and since we use “standard day” as the starting point for our calculations in the flying world, also a good assumption, I think. Last, I’ve used that formula on both my Su and F-20 to model shock wave blanking of the horizontal stab, so you’ll find it on the rotators for the concealed surfaces on both those builds. It works fairly well, I think.

    +2
  • Messerschmitt Bf-109K-4 2.4 years ago

    Well, I think you met your design objectives. It’s a close SP representation of the RL bird…IMHO; but how would I really know? Never flew a Bf myself and the game interface is markably different than sitting in a loud, shaking and tight cockpit with an actual stick, throttle and rudder pedals. But, all that aside, the performance is in the ballpark (acceleration is probably a little too fast and the 109K was heavy on the ailerons at speed, something that’s difficult to emulate in SP). It’s frightening, but not impossible, to take off and land safely. So it’s a nice 270-part representation, cockpit work is good (gee, I wish SP would give us a B&W attitude indicator) and it’s fun to fly…nice work!

    +2
  • NAA F-52-D Bronco 2.5 years ago

    It’s called the North American FJ-1 Fury. Bill Gunston in his book (remember actual books?), “Fighters of the Fifties” states far more conclusively that the P-51 was the starting point, though it was redesigned to a certain extent to accommodate a jet engine and new fuselage. Wing and tail were highly similar to the Mustang’s. But the real reason why the FJ-1 or most turbojet conversions of WWII aircraft (one could argue in favor of the F-84, but the P-47 design was totally thrown out during the P-84’s development) were so quickly phased out was that straight wings were rapidly superseded by the superior swept wing designs.

    +2
  • Lavochkin La-5FN (update) 2.5 years ago

    Really a brilliant build. I could go on about the flight model, which is pretty good, but the imaginative way in which you use fuselage slicing to craft the insignia, camouflage, use of text boxes for the flap and engine panel details, etc., is the real highlight. Very neat and accurate looking.

    +2
  • Simple F-102A 2.6 years ago

    It’s really too bad we can’t use the in-game unguided rockets as air-to-air weapons. I’ve tried, but there’s no way to do so. Though they will fire, fly and hit airborne objects (a not-quite-impossible task), there’s no way to select them for use using the AIR-TO-AIR button, there’s no air-to-air target illumination and there’s no green aiming reticle, making them almost impossible to use effectively, which is too bad as when they hit, they make an impressively enormous explosion. IRL, the F-89, F-86D and F-102 had an aiming computer for these weapons and simply allowing the in game rockets to use the air to air key would be similar to how they were used IRL. Instead, we’re stuck with recreating the Battle of Palmdale.

    +2
  • [Teaser] It's Phantom Phriday! 2.7 years ago

    @Kangy disagree; many SP builders think a G limiter FT function on the horizontal stab will restrict the G loading on a replica build and result in realistic maneuverability, but that’s not how jets (particular designs from the 1950s) work. Jets almost always have a performance reserve which allows the pilots to over G, if necessary, though pilots are trained to keep their aircraft within G limits by monitoring the G meter during maneuvering flight. F-4 pilots could and frequently accidentally did over G their jets, especially in combat. There are also maintenance inspections that are required following an over G and most jets of this type have strain plates (often in the wing roots) which will crack or deform if the jet is over G’d. Also, most versions of the F-4 had a +8.5 symmetrical G limit at lighter weights, though it certainly couldn’t sustain that loading in level flight and that’s also a gross generalization as version, load out, weight, altitude, whether or not the aileron is displaced (asymmetrical flight) and speed all affected the max allowed G loading.

    +2
  • Can ya guess the plane? 2.7 years ago

    B-29…or Tu-4…😉

    +2
  • Lautern Skyly J-2 'Teacher' 3.0 years ago

    I had many thoughts as I threw this one around the sandbox...fantastical, anachronistic, ridiculously maneuverable. The auto-aiming is reminiscent of a RL jet, the Viggen, which had a similar system and was apparently a wild ride when in action. Of course, IRL, the quick adoption of jet fighters over their prop-driven predecessors became inevitable due to their speed advantage in combat. Interestingly enough, I think your flight model reflects a prop fighter’s inability to exceed Mach due to propellor thrust limitations, as well as accurately portraying the performance limitations from your build’s general shape with straight wings and no area rule. The fastest I could get it to was in a steep dive from 30,000’...max of .93 Mach at around 15,000’. Nice modeling, especially if intentional. Of course, freezing the controls to make dive recovery in the transonic regime slower would have been a nice touch. As for the maneuverability and the Cobra maneuver...not sure that big counter rotating prop would have survived that IRL, I’d wager the two discs might collide. Perhaps not if carbon fiber...who knows? Anyway, interesting build.

    +2
  • Messerschmitt BF-109 G-2 3.0 years ago

    A very good rendition. I really like how you employ a little sleight of hand on the build itself to overcome some of the difficult bits, such as the junction between the rear fuse and the canopy glass...you also included the slope on the sides of the canopy, the bullet channels, even that spinner, which may not exactly match the prop, but is close enough to be virtually unnoticeable...very nice attention to detail. Flight dynamics are outstanding, it’s not hyperactive, but it is responsive enough. The only things I noticed is that it doesn’t lose as much energy in turns as I would expect. Roll rate is as I would expect; IRL the Gustavs onward were fairly heavy in roll, as in, stick forces were high. Too bad there’s probably no great way to emulate that in SP. The performance numbers are close, the climb is a little fast, so is top speed at altitude, but it’s not ridiculously off in any way. I kinda like the vibration effect, though it’s a little more than what I would have used, interesting effect overall, though. Very nice work.

    +2
  • Embraer EMB-121 Xingu 3.1 years ago

    Quite nice and neat with very disciplined approach to building, especially for the cockpit glass. Can’t imagine I’d have the patience to replicate the process. Flight model is also very good. Typically,
    though, reverse pitch or reverse thrust would be enabled through some sort of weight on wheels or ground sensing system, making it impossible to throw it into reverse pitch while airborne. There are exceptions to this (C-17), did you see in your research that the pilot can put this one into reverse pitch while airborne? Also, the trim tab would/should be moveable on the ground, even at zero airspeed, can’t imagine this plane IRL would work otherwise. Anyway, very nice/realistic and fun to fly! Spent a few wasted minutes just flying it in the pattern at Yeager, making nice landings, investigating stall characteristics, etc.

    +2
  • BF 109 F4Trop 3.1 years ago

    Way, way better than I initially thought from the two word description and standard screenshots. Roll is nice and snappy, as it ought to be, at least for the earlier Mes (not sure if the Gustav had gotten really heavy in roll yet). Turning seems just right (tested this on the Dev Console and 310 mph / 500 kph yielded around 7.5 Gs). Speeds are close, around 310 mph / 500 kph at SL, 400 mph / 650 kph at 30,000’. Stall is around 80 mph / 130 kph (indicated), which is also close. The acceleration / energy retention may be higher than IRL, but it does slow down in turns, which is very good and it doesn’t accelerate flying straight up, very nice. It is around 35-30% lighter than it should be, but it’s not ridiculously light, though that makes the wing loading is a little light as well and gives it better maneuverability. But SP counts the tail surfaces in wing area, so you’re also fairly close. The construction is pretty good, some interesting techniques for the German cross insignia on the fuse, as well as getting the canopy and fuselage area correct—very nice work. I also like the details, which you seem to have an eye for, such as the fact the split flaps extend slightly different amounts, as IRL. The landing reflects RL problems with that closely spaced LG...it suddenly becomes a touchy, tricky beast as soon as you touchdown, just as IRL. Honestly, it’s a great job at modeling, if it had a little better/more complete description (even without going overboard), it would get at least 25 upvotes, IMHO.

    +2
  • Mikoyan-Gurevich I-270 (Missile Powered Aircraft) 3.1 years ago

    Nice, relatively simple build of a little known rocket fighter prototype with the best part being that you used rockets to power it, so it’s really fun. The pitch rate is adequate and not ridiculously fast, though it could use more pitch and trim authority at lower speeds, as well as for the pattern and landing. It really should roll a lot faster, though, and it should fly a little faster...I’d guesstimate a rocket fighter like this should fly at least 500 KTAS (the Komet was at least that fast), especially down low, and the fastest I saw with this one was around 450 KTAS. Plus, the JATO rocket doesn’t add much thrust, if any...but it’s impressively cool looking with that big flame and lots more smoke! But it’s not too far off and it’s better than making it a 1,000 knot plane. It glides way faster than I would have expected for something with 14 lbs/ft2 of wing loading. But it works if you start out at 10,000’ high key above the runway midpoint and fly 170 KIAS and 20 degrees nose low during the 360 to landing. You do have to carefully time the round out and flare to landing, but it lands quite nicely. The last disappointment was the armament... many builders make the same mistake of using cannons as air to air armament, but the cannons really can’t hit an aerial target unless they’re XML modded. Yours are not here and it’s impossible to hit an aerial target, which is why I stick to using the original wing guns for my builds. Nice job overall.

    +2
  • Lockheed Martin F-16 Block 30 3.2 years ago

    @edensk a fully loaded Viper will barely pull 4 Gs at 300 knots. 300 knots is fairly slow, a better test is to see how many it pulls at 420 knots.

    +2
  • Lockheed Martin F-16 Block 30 3.2 years ago

    Well, this is a superior build. There are all too many Vipers on site and I thought this was going to be just another typical F-16 build. Build quality and flight model are both great. Cockpit work is breathtaking. I’m going to have to take it apart and figure out some of the really cool things you did here. It’s anything but typical, it’s truly excellent. Well done.

    +2
  • Starblazer 3.2 years ago

    Interesting build, clearly inspired by the F-94. Suggestions on future builds, recommend you put hidden SBs which activate with the landing gear extension and flap extension. IRL, those two actions add a lot of drag and are used fairly regularly to control speed as you’re approaching the runway. One time, LA Center kept us high and fast coming in to land in Vegas and we were extending our flaps and landing gear as soon as we could (below the limiting airspeed) so that we could get the jet slowed and in parameters prior to getting on final approach. For your build, the SBs are quite effective in slowing down your build, but the LG and flaps would be used more as the jet approaches the runway prior to landing and, thus, ought to contribute to total drag as they’re extended.

    +2
  • Lockheed SR-71 FedEx 3.3 years ago

    @Dest35 you’re calling me out? That’s funny 😀

    +2
  • Do you think permabanning users for being under 13 is a little harsh? 3.3 years ago

    Nope. Get a new username when you turn 13 years old.

    +2
  • NA F-100D Super Sabre (USAF) 3.3 years ago

    If I were to choose the best single build on site, I couldn’t do it...but I would put this in the top 3. Ever. So much thought, so much research, outstanding flight model. I’d do a more complete write up, but I can’t because I’m just simply flabbergasted how good this is. Better than mine. Certainly, there are new SP features which have been made since I originally built mine (blueprints mod, glass, Funky Trees), but even with these. Really, my only two complaints are the fact that it’s horribly laggy, even on my iPhone 8 and it lacks a Mach meter (I broke the code on that one a long time ago). So, it was hard to properly evaluate how much it slows in hard turns (EDIT: It does, probably a little too quickly, but it does, so, good). But, nothing else. Just wish it wasn’t so laggy, it would be my favorite build.

    +2
  • Should I upload my bomber? 3.4 years ago

    @F104Deathtrap it’s only age and experience, my friend, age and experience. But, thank you for your confidence.

    +2
  • Should I upload my bomber? 3.4 years ago

    Yes. But be prepared for a minimum of Upvotes, regardless of how good it may be. Or how good you think it is, as every artist loves their art. The lack of Upvotes is often simply a case of the number of followers you have and it takes time to gather a following. But the path forward requires uploading your creations, so go for it!

    +2
  • Ok boomer [teaser] 3.4 years ago

    @AsteroidAsteroidTheBook yeah, like me. Screw PC culture, it’s an abomination and runs directly counter to free speech. It’s the idea that one must be polite, or suffer the consequences. Well, as a free human being, I should be able to express my thoughts and you should be individually free to disagree with me. In the past, before this stupid idea of Political Correctness evolved, the tend was to generally allow free thought, speech and expression. Those you disagreed with, you either told them so, or you simply avoided them. This was in line with “keeping polite company”. If someone decided to espouse controversial/reprehensible ideas, we simply disagreed and society moved on. Now, we shame them for simply thinking the “wrong” thing, no debate, no discussion. The kicker is that the idea of wrong or right is established by only one side with a single opinion and pushed on the rest of this with the mandate to “agree or die”. Disagreeing with things because they run counter to thousands of years of society, run counter to religious dictates, personal mores or standards or simply logic doesn’t necessarily make someone evil, it simply is a disagreement over an issue. A hallmark of a vibrant and just society is the free expression, exchange and debate of ideas in search of the truth. Ever heard “I may disagree with what you say, but I will defend to the death your right to say it?”. That’s no longer the mantra of today’s society and we are losing more freedom daily, a loss of free thought. And don’t kid yourself, this isn’t about truth...if so, PC culture wouldn’t seek to upend every standard or idea, but it does. It’s about power. As Pontius Pilate said: “What is truth?” What he meant is: “Who cares what the right thing is, as long as I have the power.”

    +2
  • To IAS or to not IAS? 3.8 years ago

    IRL, an aircraft’s “top speed” is its fastest TAS, or how fast it moves through still air. IAS, which is measured by the force of air molecules entering a pitot tube and impacting a diaphragm, varies greatly by air density and is much closer to TAS at sea level, where the air is denser, but much less than TAS at high altitudes, where the air is much “thinner” or less dense. However, IAS is very important to a pilot because an aircraft always stalls at a given IAS...though an aircraft’s TAS may be very high at high altitude, it’s IAS is much lower at that high altitude. So, regardless of altitude, an aircraft will stall at the same IAS (disregarding compressibility) because IAS is the best indication of how much air is flowing over the wings, tail and fuselage as it automatically considers the density of the airflow. Prior to the advent of GPS (or inertial systems or Doppler Radar), pilots and navigators had to compute their TAS based on their IAS, air density (temperature and altitude), and forecast headwind/tailwind, or looking at known landmarks, in order to determine the distance moved across the ground as there was not a “TAS indicator” until the advent of inertial reference systems. However, IAS has always been just as important because IAS, more so than other speed indications, is the easiest and best predictor of aircraft’s ability to remain airborne and handle properly.

    +2