This crew revealed a problem with this plane by going closer to the test limits. Unfortunately they had to offer their lives, but probably saved a lot more lives by doing so. May they rest in peace!
May all folks who have sacrificed their lives for the betterment of safety RIP. Safety rules and checklists are truly written in blood, as MACI said. Now don't get me wrong, I love t-tail aircraft, but would a set of small retractable canards in the front of the plane prevented the stall from becoming an accident, so that t-tails can recover from severe stalls? That would cost a lot of money though.
@@Maven0666 When you mean as a consequence of stall? Yes, but since a plane pitches up when about to be stalled, the tail goes down. Planes with conventional elevators, these elevators move downward with the tail and stay below the shadow. However T-wing elevators are already several meters above the tail, and when the tail moves downward, the higher elevators now move exactly into the shadow, thus making the elevators non functional. The plane can now longer be leveled or pitched down to prevent it from stalling: deep stall.
yes. When I learned to fly my instructor said " you won't live long enough to make all the mistakes others have made and learn from them. So take the easy option which is to follow the rules and procedures.
@@nztv8589 Yeah like "plan your flight and fly accordingly to your plan" and all that bs.... So now you think you'll never make mistakes and that your plans will always be right?
When I was in fire academy, we had to memorize certain rules for when you're on a fire line. Near the beginning of us trying to memorize them and none of us really had, they yelled at us about how every single one of those rules had been adopted because a firefighter had lost their life that way.
I'm quite sure I heard it in English as well but when I was doing a training on how to use oxy acetylene torch, some people bitched about overkilling it on the safety measures. The old guy just came in, turned off their equipment and told them " The rules of safety are written in blood." and sent them away. I don't think some of them understood what that phrase met...
Probably the wrong word. It's not an accident, it's a testing incident. An accident implies the actions that lead to their death were unintentional, but they were deliberately testing the stall, and a stall is exactly what they got. They just weren't planning on not being around to see the following day.
The angle of INCIDENCE is the angle between the wing chord line and the fuselage datum line. This is fixed by the design of the aircraft. You should be referring to the angle of ATTACK, which is the angle at which the air meets the wing.
There is a difference in terminology between the two sides of the Atlantic in respect of 'angle of incidence' and 'angle of attack'. This was recognised way back in the 1940s by Langeweische in his book 'Stick and Rudder'. In a career lifetime in the design of gas turbines here in the UK, I can tell you that the term 'angle of incidence' has been used to define the difference between the air/gas angle onto the leading edge of an aerofoil, relative to the local angle defined by the leading edge at which the angle of incidence would be zero. 'Angle of attack' has typically been used to define the angle of an aircraft relative to its direction of flight.
Angle of attack is the angle of the aircrafts flight path with reference to the relative airflow. The chord line is the reference on the wing. Hence you can be in a stalled condition at any pitch attitude or any speed.
Further to my previous comment, some years ago, I had an argument on RU-vid with one of our American cousins. He just could not accept that a difference in terminology from that in use in the USA was valid - even though it was recognised by Langewiesche in 'Stick and Rudder'. I even quoted him the page number of the reference.
It's very sad so many pilots sacrificed their lives for all of us. I wish there was a way to personally thank those that gave their lives to help keep us safer. My thoughts and prayers are with you brave pilots and your families.
I met test pilots in the service. They are dedicated daredevils. I realize the chances & scarifices they take. S few told me they ejected when the plane did not react as expected. Or it caught on fire. What guts.
Mike Lithgow survived a ditching in a Fairey Swordfish in 1942. He and my grandfather were very good friends and fellow test pilots. My middle name is Mike because of him. I was a year old when he died. Through my career as a pilot I carried my grandfather’s navigation computer, a few years ago I took it apart for cleaning and found Mike’s name on the inside, it may have been his to start with, but I don’t know. I did however fly 3000 hours on BAC1-11 very safely.
The deep stall phenomenon was unkown at the tine! All T-Tail aircraft are prone to it and therefore aircraft like the B727 and the DC-9 family all have pushers.
There was one russian plane literally not able to recover from a stall by design due to it's massive T shape. Quite worrying to fly it on low energy/speed :D.
I've never been a nervous flyer. But, March of 1986 I was flying ELP - ABQ on a Western Airlines 737-200. The distance between the two cities is minimal, so we were not that high. Between El Paso and Albuquerque is the Franklin Mountain range. It was choppy. How choppy was it, you ask? The stewardess at one point was collecting bevvies. She hit the deck on both knees and, holding onto an arm rest (this is where flight attendant training shows), she raised her voice (not shouted, not screamed), "HOLD ONTO YOUR DRINKS!!" She didn't say that not holding onto them would endanger your life because they could become airborne and lodge themself into your skull. I began to freak out. Looking out the window, I realized that the test pilots put these airframes through torture that nearly breaks the airframe apart before the FAA certifies them as airworthy. At that moment I relaxed.
Right. I've been on test flights from RAE Bedford. We weren't doing anything to test the limits, we just weren't as concerned about not upsetting the paying passengers and had two ETPS graduates at the controls. On one occasion that resulted in one of my friends floating back down the plane in a zero g pushover. In another it resulted in all of us feeling like we'd spent an hour in a tumble dryer. It's funny when you turn up to the plane in office clothes and the pilots turn up in full survival gear, but they were serving RAF officers and they could be hauled off to Wales to a survival exercise any time they went out to fly. When we were bouncing through turbulence I was in the jump seat, at first I was really concerned, then I noticed that the two pilots were chatting about video games. Ah. No problem then. Live tests never come near the ultimate load limits of the aircraft, most people will never experience even half the ultimate design load. The static tests aim to reach 150% of designed ultimate load. Normal g limits for commercial aircraft are +2.5 and -1. China Airlines 006, a Boeing 747SP reached +5g which broke the APU off its mount, broke some overhead bins, and gave the wings a permanent set.
Great video, as usual. May I suggest something? What you were calling „angle of incidence“ is actually angle of attack. The angle of incidence is the angle between the aircraft longitudinal axis and the airfoil reference line (basically, how the wing is attached to the fuselage). It’s usually something which on most airplanes cannot be changed, unless being extremely destructive. One airplane which could vary that is the F-8 Crusader, because it’s geometry didn’t allow sufficient angle of attack (and thus, lift) to be produced during take off and landing from carriers. So, the guys at Vought built in a hydraulic jack where the front end of the wings could be raised a few degrees for that purpose. The angle of attack is the angle between the airfoil reference line and the approaching air.
^^^ What Johnny said. Angle of incidence can be altered slightly by flap/ slat extension but OP needs to be saying angle of attack. Also, many people confuse aoa with deck angle.
Amazing video, as a chemistry teacher I always emphasize to my students the fact that safety features and regulations exist bc no matter how small or insignificant they may sound, someone most likely has lost their life. I will be happy to show my senior students this video as a real life example. Thanks for your content! Love from Mexico
As a taxi driver, I always emphasize to my clents (to keep them quiet and therefore make my day easier) the fact that safety features and regulations exist bc no matter how small or insignificant they may sound, someone most likely has lost and will lose their life.
Due to T-tail stalls being unrecoverable by normal means, T-tail planes require special stall recovery procedure, such as using a tail drag chute or tail pitch rocket where available, or banking as high as 90 degrees to exchange deep stall for a steep dive which IS recoverable.
Great video, as always, many thanks for sharing it with us! I know that problem from the DC9 my dad was flying for decades and I was working on it as an engineer in the 80's. On the DC9 a locked in deep stall situation could occur as well. That is why the DC9 's had among other things an elevator power system allowing an elevator nose down command even when the t-tail had almost no air flow. As far as I can remember the "elevator pwr on" light was one of few blue/green indication lights on the annunciator panel. The system was checked during pre flt check by pushing the steering column full forward. Kind regards from Vienna, Austria
The DC-9-10 was literally on the drawing boards when this crash happened. In the late 70's, I was told by a senior DAC engineer that the area of the DC-9's horizontal stabilizer was increased by "50% overnight" after the crash. I don't know whether the chord/span literally got bumped up by 22%, but nonetheless an indication of the effect this crash had on airliner design going forward. IIRC the MD-80 also experienced persistent deep stall during flight testing, but as expected from analysis was able to recover by the time it reached thicker air around 10k feet. Or maybe it was higher than that, and 10k was the designated bail-out altitude if the stall persisted? The test aircraft was outfitted for quick egress by the minimal crew, with the forward cargo door rigged to open when the first person jumped down a hole in the cabin floor above it. Also don't know whether the powered elevator for recovery had been developed at that point, or was turned off for the test, or ??. So a fuzzy and incomplete memory, but I'm passing it on with that caveat. Maybe someone who was actually involved with the flight testing can chime in.
@@marcmcreynolds2827 Yes I have heard about that but when I started we had a DC9-30 fleet, so can't say a lot about the series 10. Over the time we got 50's and 80's.
@@marcmcreynolds2827 yes I really think they didn't know that was possible at the time, and learned the hard way. I can only imagine what not being able to do anything and falling like a rock feel like. I wish they were able to escape the plane to tell the tale
@@nigo1787 My understanding is that they did stay in radio contact all the way to the ground. I'm fuzzier on specifics, like whether control movements for recovery attempts were being relayed in real time, but it seems there was a good technical account as to what was going on. That would have gone a long way towards dispelling questions afterward of for example whether hardware failure had been the cause, thus allowing the engineers to zero in on corrective action.
7th June 1964 there was another 1-11 crash during stall testing. This was G-ASJD, but it had been fitted with a tail parachute to be deployed in the event of a deep stall during the testing. During the testing the pilot believed he'd lost elevator control and deployed the chute. The aircraft stabilised but the pilot did not then jetison the chute as he should have done. The result was the aircraft making what ended up being a very gentle belly landing on grasslands near a village called Tilshead. The aircraft was barely damaged and the crew walked away. The details are on the ASN if you want to look it up.
I haven't commented since probably your fourth video but I want to thank you so much for all you do and what a wonderful channel. Your accent has improved so much. keep up all the hard work brother.
It’s the Angle of Attack (AoA) which was exceeded and got them into the stall - not the Angle of Incident! The Angle of Incident is a fixed value and denotes the angle between the chord line of the airfoil and the longitudinal axis of the plane. It is a designed feature and cannot be changed by the pilots! The elevator controls the Angle of Attack, i.e. nose up or down.
Wow. I worked that plane as a crewmember hundreds of times...in the late 80's. They were originally Mohawk Airlines...if you know your airline genealogy, then you will know who I worked for. I had no idea about this flaw, thank God.
@@ChrisCooper312 All of which I have worked. And the Fokker 100 too. As I said, I'm glad I didn't know this. We had a tragic history with the Boeing 737-300, as well. Don't even ask me how many flights I worked on that plane...before the uncommanded rudder flaw killed three of my friends. I tried to avoid it...working our T-tail equipment and the 75 and 76 instead! Even the jack screw challenged MD-80. By the way, a flaw is a flaw. No quotation marks are required.
It was reported that one of the test flight.observer had written on his paperwork that they were in a deep stall and couldn’t recover. I also heard that BAC fitted a tail parachute to pull the tail up until they fitted the stall stick shaker and stall pusher. I also remember Mike Lithgow used the fly the Supermarine Swift fighter at the then annual Farnborough air show at supersonic speed by putting it in a dive while aiming at the airfield resulting in a loud sonic boom. Those were the good old days of British aviation.
My first jet flight was on a BAC 111 and I flew on them a few times. Thanks for the accuracy of your reporting of this very unfortunate incident and its causes.
Beautiful video, for the basics and more advanced knowledge alike. As excellent as normal. Also, your English is almost perfect (from a native speaker), and you are very good at explaining complex topics in ways that the average viewer can understand. The video complements the commentary very well.
The most interesting part of this video is about the explosive bolts. I knew that test pilots of new airliners wear parachutes and protective suits, but didn't know how they'd get out.
So that's how we discovered the deadly weakness of T tails. Never really thought about it until now. But now that I know how we learned this, I'm wondering what else we learned through someone else's death.
No other deep stall on this plane, but if you look at the story of the MD80, which has an identical configuration, you'll find them, and much later than 1963, like the West Caribbean Airways Flight 708 in 2005
When I was a kid I built a balsa/paper model of the Wright Flyer. Noticed that at certain angles that it would always enter an unrecoverable stall. This was due to two factors-drastic changed thrust vectoring, but most importantly no airflow over the elevators assembly due to blockage of the wings and body of the plane. Bad design that unfortunately has been repeated ever since.
@@brucebaxter6923 except that at too steep a attitude you now have two surfaces creating drag instead of just one, and like the jet that was lost does not have variable pitch to compensate
@@TheFULLMETALCHEF Missing the point. Two surface creating lift and stall proof, What you lose by increased drag on the front you gain by increased lift overall.
I was with 34SQN RAAF in the mid-80s - we flew the BAC-111 in VIP configuration. The stick shaker/stick pusher test flights were the scariest, considering we all knew about the unrecoverable deep stall. However, the stick pusher occurred well above the stall speed and it was nearly impossible to pull against it. Oh yeah, it also had a loud claxton horn that went off just prior to stick pusher, which scared the hell out of you. Rule number one - keep the airspeed above stall.
The DC-9 had the same problem. I was talking to a mechanic on the test flight---they were filing the throttle to get more power. They too got into a deep stall. They added fences on the nose to disturb the air during a deep stall.
Thrust vectoring in all directions would aid in control of aircraft that experience many types of control problems. It would add another level of control.
Yes, but it also adds an additional layer of expense, complexity, and maintenance. It needs to be kept in mind that adding thrust-vectoring isn't as simple as slapping a vectoring nozzle on the engine. All aircraft with thrust-vectoring capability were designed from the start with that ability in mind (or in the case of the F-35B, are a factory-build variant, _also_ specifically designed for a thrust-vectoring engine); you can't just slap thrust-vectoring engines onto any old aircraft. For example, try slapping thrust-vectoring engines on a 737, and it's engines are likely to actually rip themselves off, as the pylons were never designed to handle twisting stresses from an engine vectoring to the side (or the engine trying to lift itself up, for that matter). We'd probably need to return to something more akin to the Comet's engine-inside-wing layout to get the advantages of vectored thrust, and commercial aircraft design moved away from that for good reason (for one thing, doing maintenance on those engines _had_ to have been _incredibly annoying)._ Something else that needs to be kept in mind is... does the aircraft even _need_ thrust-vectoring? Is it something that would be used with any kind of regularity (thereby justifying such an expensive engine modification)? With commercial aircraft, the answers to those questions are likely to be: only for short-field takeoffs and loss-of-control emergencies, and no. Would thrust-vectoring make aviation safer? Maybe. But also maybe not. But what it could _certainly_ do? Drive maintenance costs _through the roof._
@@benjaminfinlay829 Also, it's something else to go wrong. As Boeing found out, adding in a fancy new system to deal with one problem can cause it's own problems if it doesn't work as it's supposed to.
@Alfred Weber I agree, I am very much against pilots flying planes. A simple weight sensor on the landing gear would determine balance and load on the ramp before engine start and give a go no go then set takeoff length and speed and give a go no go for its particular runway, check it’s minimum sensor/instrument functionality and give a go no go etc etc. Note, navigator and engineer in cockpit instead of pilots.
Thrust vectoring on a rear engine aircraft like this might have benefits. It might even be a better way to trim (less drag) than elevator trim. On a 737, with engines under the wings I doubt it would do anything useful.
Not really, the 737 had a system to alter the pitch when the angle of attack was too high. This was put in place due to a last minute change. The engines were too low to the ground so they were moved forward, which altered the center of gravity. MCAS was put into place to pitch the plane down to compensate for the shifted center of gravity. 737 MAX’s problem is because a single faulty Angle of Attack sensor causes MCAS to think the plane is pitching up when it isn’t, so it keeps pitching the plane down. This incident, the plane is actually designed in such a way that the wings block the air flow to the elevators at a high angle of attack, and the plane CANT pitch down. In 737s case, you can disable MCAS and override the system (the pilots just didn’t know how in a panic due to incomplete training by Boeing). In this case, it is physically impossible to pitch down.
@@nevelis Absolutely correct except that for the MCAS, there was not "incomplete training", there was no training at all and this was the aim by the way to compete with the A320 Neo. So the crew of the first crash (Lion Air) didn't know about MCAS so that they didn't understand what was happening. The crew of the second crash (Ethiopian) was aware of the MCAS possible trouble and informed about what to do in case ... and that's what they did. The copilot was the first to understand the situation and they did quite well: they switched off the MCAS asap, as recommended by Boeing but it didn't work since, in the meantime they had got so much speed in the dive that the aircraft was not recoverable. Disabling the MCAS was not the solution and anyway it had to be done within 10 seconds maximum! The solution was (is) 2 sensors instead of 1 and additional training related to the MCAS. From my perspective, trying to compete with Airbus implementing a new modification on a very old aircraft was probablt a bridge too far, not mentioning the mind blowing lies ... Just my opinion.
@@patolt1628 True. MCAS (Might Crash Any Second) was sort of a band-aid fix to deal with a basic design problem caused by modifying a half-century old product with bigger engines and a newer wing design. For pilots struggling with dangerous MCAS inputs the "solution" was to disengage that system, leaving pilots with the original design flaws that it was intended to fix. As you mentioned, the additional sensor and additional training seem to work now. Still, it's time for them to come up with a new aircraft.
@@nevelis Moving the CG forward would actually create a nose-down tendency for the plane. The problem is a bit more complex, related to the lift created by the engine nacelles. Also, you are missing the fact that it is not as easy as "just disable MCAS" - the crew of the second crashed plane did disable MCAS as per Boeing instructions, and it still was impossible to recover from the crash.
I think the most true quote I can ever quote from a teacher that I knew. He was talking about a NASCAR wreck that lead to restrictor plates. A very famous one you are sure to know, Bobby Allison. He said "It takes someone to die before anything changes" And time and time again I see it happen every once in awhile. The reason we have so many safety features or safety precautions is because of someone passing away or getting severely injured.
@@benjamin4281 @crunchtastic1948 As explained in the video, the T tails can enter the deep stall where the aircraft loses the elevator authority, making it hard to recover. The thing with rear mounted planes is, adding thrust causes the plane to pitch up, which you'd normally counter with the elevator
Rear mounted engines will always come with a t-tail, due to the engines being near where the horizontal stabilizers would normally be. I wouldn't say that configuration would be dangerous, as many "modern" planes have that configuration (ex: most private jets, CRJ 100 series) but you do have a point. (Edit: Rear mounted engines can also come with a 'cruciform tail')
It's hardly dangerous, especially as it was used by some of the most common planes of the 60s and 70s (the BAC111, DC9, MD80, Boeing 727). In this case there was a danger, but they discovered it and made efforts to ensure pilots would not get in a position where the plane might deep stall. It was also found that the 727 could get into a deep stall when using flaps 40 (the maximum setting) under the right weight and centre of gravity, so many operators either banned flaps 40 being used or even physically locked it out.
Why? Based on jingoism or something scientific? High-tail plans have terrible stall characteristics. (like the Trident crash at Staines). These planes were also disgracefully noisy.
True, but there are also benefits to the T tail design. And designers can always convince themselves that the problem is a "corner case" that will "never happen".
I mean, it was in the 1960s, the aerodynamic phenomena was not understood as much as we know today. They did not fully understand the limit of those phenomena. I think it is one of the driving factors of those BAC pilots exceeding the limits, to obtain more understanding to the aerodynamic characteristics. Sadly, it resulted in a dire consequences.
Thanks for another great video. As a former RC pilot in the 80’s it’s not always necessary to die to learn how to fly safer. We trained on getting out of spins and stalls and aerobatics. In this situation I would try to roll out using the ailerons to allow the tail catching some wind. If nothing seems working, try something else
My father was shocked when the prototype One-Eleven crashed as he worked on it as an aircraft fitter at Hurn Airport Bournemouth. When the internet became widely available I found an article on the crash. Apparently there was a stall system which operated in part by a hydraulic tab on the tailplane. The pump was undersized and failed plus the pitch reading was incorrect. When the pilot realised he was in a stall he was not aware the pitch was greater than the reading. Being a WW2 fighter pilot he tried a few manoeuvres but it was too late. On impact the forward movement was 75ft. The exit door was still in place as all the bolts had not been fired. The final comment was that military aircraft undergoing stall tests could deploy a tail parachute to bring the nose down. I’m not saying the article was correct but it is how I remember it.
A bit like in physics how Bernoulli and Euler followed Newton, Clerk-Maxwell and Faraday followed them and in turn Einstein and Bohr continued and built on their work - so in aircraft engineering do you get the culmination of generations of knowledge and experience brought to bear in the design and construction of the latest, safest, most efficient airplanes - even the most successful aero companies with the most gifted designers don't do it from scratch. It's great to see a MACI clip highlighting the skill and dedication of those who went before, much as we enjoy the more usual stuff involving commercial flights gone wrong. As always, very nicely explained and easy to follow even as a non expert....
Remember (just in case) from some other disasters and reports, that if you bank far enough, the nose also pitches down... You CAN also use some rudder (pedals) with the ailerons (roll) to accomplish this... It's important as we take controls of larger machines and take responsibility for more lives by rote, that we remember "There are more ways to kill a cat than to choke it to death on strawberries." You probably won't ever need to use that knowledge... BUT it's worth watching a lot of these accident and disaster videos to notice things like that. If the elevators won't help directly, roll to the side and kick the hell out of the rudder. You can get that nose down if you act quickly enough... AND once the engines get clean air, and you've got some speed back, level out and pull up GENTLY... This is NOT to take away from these wonderful pilots and people!!! May they rest in peace, there was NO precedent for a deep stall or super-stall, where the engines AND horizontal tail end up in the "shadow" of the wings, and lose efficacy. NOW that we know, we have shakers and pushers on a LOT of sticks because a LOT of planes have the "weakness"... There are also other pilots and lives lost for us to find out that a hard bank (say... in excess of 40 degrees) can drop the nose... AS CAN a bank and rudder control... Let's keep ALL their sacrifices respected and valued by keeping EVERY lesson we can learn... just in case we might need it one day. ;o)
Thanks buddy , you must of put that up at a different time , was not there at midnight last night Aussie time , good work I don't know how you get the time to give us 2 videos in a week
6:20 Yes, this is called shadow masking. There is no laminar airflow over the tailplane as the airflow is masked by the severe turbulence from the wings. This is common for all planes with T-tails like the HS Trident, Vickers VC-10, Boeing 727 etc.
A very similar accident happened to a Hawker Siddeley Trident airliner in 1966. G-ARPY was on a test flight before being delivered to the airline and also entered a deep stall. It crashed in Norfolk, England and all on board died.
Small correction. When you say angle of incidence you mean Angie of attack. The angle of incidence is the angle between the wing cord like and the longitudinal axis. It’s fixed per airframe.
Just an FYI...You wouldn't say, "To say that he's one of the few people who knew the plane best would NOT be an understatement." Saying he knew it best WOULD be an understatement. No biggie, just some constructive criticism from a faithful subscriber is all...Another great video BTW. 😉✌️
Elevator blanking in a T-Tail is one heck of a terrifying design flaw with the concept of T-Tail aircraft. Personally, I would require the use of a small canard on all T-Tail aircraft to provide Pilots just a little bit maneuvering ability in the event of a stall like this. It's surprising they didn't try lowering the landing gear. Although it wouldn't have done a lot, it may have been enough. As tragic as it was, they succeeded in their goals - they provided important data to the engineers which saved a lot of lives in the future.
It's not angle of incidence, it's angle of attack when you are flying. The angle of incidence is the angle the wings are mounted to the fuselage, as shown in the illustration at 3.50 and this angle obviously never changes.
The data recorder print-out shown in the video refers to something called "true incidence" and the figures for it suggest that it was at the time a term for what is now called the angle of attack. Other technical terms have changed over this period, for example the tailplane and fin have become the horizontal stabiliser and vertical stabiliser. Also the terms port and starboard (which appear on the print-out) don't seem to be used any more.
That feeling in the pit of your stomach having no elevator control must be like driving on the freeway and turning the steering wheel and nothing happening. Damn.
I think you have mixed up ANGLE OF ATTACK WITH ANGLE OF INCIDENCE. Angle of attack is the angle between the cord line and the Relative Airflow so changes in flight. 15 degrees is normally the maximum before the stall (although I think delta wings like Concord can go to 22) Angle of incidence on the other hand is fixed by the aircraft designer and does not change, although I think there are some fighter jets that have a variable incidence, wing, but I may be wrong about that. The wing is actually developing maximum CL at 15 degrees just before the stall.
The correct term would be "angle of attack" and not "angle of incidence". The incidence is the angle between the fuselage zero line and the wing chord line, i.e. it is a fixed angle for most airplanes unless it's a tilt rotor with tilting wings. The angle of attack however is the angle between the wing chord and the incoming airflow, that is what causes a stall.
the best reaction to a stall is not to put the engine on full power, but to do the oppesite, this will force the nose down and you will soon have enought speed to get out of the stall, this is something you learn as a combat pilot
The narrator of this did not explain why the nose went back up when the pilots put in maximum power. The deep stall phenomenon was not known very well at all in those days, and the pilots probably did not realize if they accelerate the air underneath that tail by going to high power, then the air pressure under the tail is reduced, and the air pressure above the tail is higher, will shove the tail down, putting the nose back up in the air. Kind of a counterintuitive thought, but they needed to keep those throttles back until the nose was down. So that airflow could be restored and airspeed increased. I flew both the DC9/MD80, and the Lear35. Both of those aircraft had a very strong stick pusher that would shove the nose down . in the case of the MD80, It’s a force of 80 pounds on the column and it will shove the yoke forward violently when you activate the stall warning. It’s activated several knots above the actual stall so you still have airflow over the tail when the elevator starts coming back down. it does that by a hydraulic circuit in the down elevator. That’s the only hydraulic flight control for pitch. Otherwise the elevator is cable operated with servo tabs. Douglas actually put an additional device called ventral strakes, underneath the nose on each side to help energize airflow over the tail at high angles of attack. That gives even more control in an extreme pitch situation. Just one more thought. The only thing that would’ve got the nose down quickly with no airflow would be a weight shift system that would allow weight to be moved forward very quickly from a cockpit control. If they could’ve moved a couple thousand pounds forward in a matter of seconds by using a weight shift system in the cabin that would’ve put the nose down. I’m guessing they had no such system installed . It’s obvious to me if they had known all of the dangers of the deep phenomenon they would’ve taken additional steps to get the nose back down in a loss of control situation.
You do a great job and I enjoy your videos! There's a bit of confusion about the angle of incidence vs. the angle of attack (AoA). The incidence is the angle of the wing chord line relative to the longitudinal axis, it's fixed (except the FA-8 Crusader and perhaps another one or two). The AoA varies during flight and increases as you approach a stall. If you lose elevator control, with enough altitude you can roll 60 degrees or so and apply rudder and pivot the jet to lower the nose. Cheers
For those who haven't worked on aircraft let me tell you -- the stick shaker is not very subtle. It is a violent movement designed to get your attention!!
I don’t know if it’s true or not, but I’ve heard that test flights have to carry a reduced amount of fuel because they have to allow for the weight of the pilots’ balls.
I must have flown hundreds of times in BAC-111s out of Gatwick in my 20s, working as a computer engineer attached to British Caledonian, of course they all had pitch shakers and pushers by then. British Airways flew Tridents too in those days and I think it was one of those which "reversed" into a reservoir coming out of Heathrow due to a deep stall.
The test pilots also found this out on the Trident , that stalled at 30,000 feet on test. I believe the flight engineer bollocked the pilot all the way down, previous stall conditions had gone into the stall with one wing down, the pilot on this test flight went into the stall wings level, The aircraft also had factory workers on board it was a jolly for them, All died.
The angle of incidence is the angle between the chorď line and a line between the fore and aft axis of the aircraft. It never changes on an aircraft. What you meant is the angle of attack. This is the angle the chord of the wing makes with the relative airflow.
Stick-shakers have prevented untold number of T tail deep stall tragedies...as long the pilots don't disable the warning device. Which is what happened with British European Airway's Flight 548, a Hawker-Siddeley Trident, which crashed minutes after take-off from London Heathrow in May 1972 killing all 118 souls on board.
