Thank You Martin for bringing this to us and Thank You Doug for explaining something that is always a bit hazy for most pilots. Whenever we think there is absolutely nothing more we can possible learn, along comes a Doug and makes it all very clear for us. Fantastic! I once got a birthday gift from my wife and took a mock combat flight at Fullerton, CA at Air Combat USA. We pulled 4.5 G's which as a civilian pilot, that was the most I had ever experienced up to then. We flew the SIAI-Marchetti SF.260 which is a side by side trainer.
I explained this to my kids a 'few' years ago. The positive G curve plots an infinite number of points where the wing can 'give' a specific G loading, at the specific plotted airspeed, without exceeding it's critical angle of attack. As you stated, there are other factors, such as asymmetrical wing loading, I think that the pilot manual I learned from glossed over this last factor, and only mentioned that it could be a factor. Also overlooked in that training is the very real difference in stall speed between lightly loaded aircraft and one that is maxxed out. More emphasis is put upon the 'wing will stall if it exceeds it's critical AOA, regardless of airspeed', without clearly stating that a heavier aircraft will require more AOA at a given airspeed, to continue level flight. It's all in the wording. Thanks for this excellent video.
All good points. I would add that heavier aircraft will require more AOA at a given airspeed not just to continue level flight, but even to continue a sustained climb or descent (with a constant vertical speed). - Martin
Excellent! Owned and flew a Super Decathlon for several years. Took aerobatic instruction from a couple of professionals and never had this explained to me. I flew all the maneuvers listed in the POH and never had to exceed 3.5 g's. I distinctly remember and the plane showed me how adding g would increase turn rate and limit airspeed. Never got in a situation where i needed to pull 4+ g to avoid the ground and learned something new from this discussion. Really enjoyed the video, thanks.
I've never seen those concepts explained so concisely and explained exactly how all the numbers were arrived at. I feel a lot smarter having seen that. Thanks for sharing it.
Always Nice To See Captain Doug and Captain Martin Working Together ! More Than Important To Know All of That, And, If Possible, To Have It All In The Blood Stream, Naturally, THROUGH TRAINING ! I Met a Captain a Long Ago (Captain Ferreira From TransBrasil Airlines - RIP) Who, In The Early 60's, Did His Aviation Training, Which Included Soaring Flights and Aerobatics, What is The Focus of Captain Doug’s Class. To Acknowledge in Advance What The Plane Is Capable Of, As Well As, To Aknowledge Upset Maneuvers and To Know What To Do In Case They Happen Unintentionally or Inadvertently To Prevent Bad Reactions As "Startle Effect", "Tunel Vision", Etc., What Could Cause a Serious, However Avoidable, Accident. By The Way, In The Multi Engine Training Episode (The Drill - Part 1), Captain Doug Said : " We'll Beat This In Your Brain At The Same Place In Your Brain Where Mary Had a Little Lamb Exists ..." ! In The End, Like Captain Doug Said : To Be a Better Pilot ! Many Thanks ! Best Regards ! Ed
Tremendous teacher Doug. Thank you for bringing this to us Martin. I would like to add asymmetric, or rolling pullouts can affect the GA pilot and here is how. The initial concern in the rolling pull is structural limit, as speed decreases you will enter the slow speed regime and one wing will stall first. The high wing will have a higher AOA and therefore stall creating a un commanded roll in the opposite direction. Very often you see this in crash footage, usually a security camera near a crash site. I belief it’s the reason most fatal GA crashes occur. Not keeping the wings level nearing stall speeds with GLoad, ie pulling away from terrain. Thank you again. Sharing this is important for us all
Omg I just wanna say thank you. This has been the best video regarding the Vg diagram I have ever seen. The maneuvering speed illustration of how it decreases with a lighter wight was just insane. So many people explain it in a weird way but seeing that was crazy. Gonna rewatch it several times so I can teach this well
Thank you gentlemen! This is excellent. I spent a lot of time trying to understand weight impacts on the envelope during my training, but never really go it. It always seemed backwards to me. I get it now. It's crazy that just adding the words "give" and "take" can totally unlock a concept. That V^2 will get you... These lessons you guys are recording are incredible. A lot of training seems to be memorizing, not deep understanding. You and Doug are changing that. Please keep it up, the GA community is grateful!
No rush - this is one you should come back to in a year or two. Then it will help answer questions which at this moment you may not have wondered about yet. - Martin
This is truly excellent. Doug is really smart and an excellent teacher. I’ve done EMT or upset recovery and we talked about many of these things. I have to admit that I never knew exactly where Vno comes from.
One of the best vids I've come across that might keep me safe as a GA pilot. One thing that really got my attention is the first statement that Doug made about RV and Experimental aircraft owners in general, and their lack of understanding of this graph. I am considering purchasing an RV8, and have wondered about how to fly acro in them, even as the G limits are clearly stated. I have formal acro instruction in a Decathlon, but if I do purchase a -8, I want to be damn sure I am flying/maneuvering the plane well within its limits. This vid was very helpful, although I will have to watch it again to be certain that I fully understand conceptually this Vg graph. Thanks for doing these videos.
Very valuable video. Doug has a really great way of making the difficult to grasp seem so understandable. I particularly liked the explanation of the "rolling g" issue, because I knew of this for years, but never really understood the reason why. Great service to the aviation community Doug and Martin
Thanks Martin, I learned some things. I'll use this video when explaining Va vs weight to students. It makes a lot of sense this way. Keep making great content. It's also worth noting that when recovering from an unusual attitude, rolling first and then pulling is more effective because roll rate decreases with G loading. Unload the wing, roll level, then pull.
Great video! I work as a pilot in skydive ops for a living, so I find myself daily at the edge of the envelope. I believe it is crucial for anyone operating in similar ops to be familiar with the structural and aerodynamic limit, as the "do not exercise full flight control surface deflection above Va" is simply wrong and can sometimes be dangerous. E.g. when pulling out of a dive at 0 deg pitch attitude you're very likely to be within the limit load factor margin and could apply full elevator low in order to maintain level flight and avoid stalling.
Super interesting, Martin. Thanks for putting this together. And great find in Doug -- a wealth of information. He has a way of imparting very complicated data in a way that simple(ton) people like me can understand(ish). Thanks again, Martin.
Not painful at all. Doug's (excellent) teaching style includes a lot of questions to guide the discussion and keep the student engaged and alert. It's always a pleasure to sit down with Doug and learn from him. - Martin
I'm currently working on my PPL theory, and this video came at the perfect time! Thank you Doug for explaining it and thank you Martin for getting Doug on video!
Why does maneuvering speed decrease with weight? It's all about angle of attack. Take two identical normal category airplanes flying at the published Va: one is very light, one heavily loaded at max gross. Regardless of their weight, both airfoils will stall at the same critical angle of attack. The light airplane flies at a lower AOA for this given speed, compared to the heavy airplane which must fly at a relatively higher AOA at all times to produce more lift. So the heavier airplane (for a given speed) is always closer to a stall. If the pilot of the heavier airplane yanks back on the controls (or, encounters some turbulence, which is essentially the same thing), there is exactly enough AOA remaining for the wing to generate +3.8G's just as the critical AOA is reached. The stall acts as an aerodynamic safety valve which releases the pressure, protecting the airplane from itself, returning it to ~1G. But the light airplane has much more AOA left to play with, and therefore much more potential to generate higher G loads. If the pilot of the light airplane doesn't want to bend or break something, he must 1st slow down to the weight-corrected maneuvering speed, thereby increasing his AOA and lowering his potential to make G. You can calculate Va for any weight by multiplying the Va at max gross by the square root of the weight ratio. (actual weight/max gross) Additionally, it's the _acceleration_ which produces stress on the airframe and the G's which you feel on your body. Force = mass * acceleration Imagine a 30fpm vertical gust of wind exerting the same force on those two airplanes: one light, one heavy. The same force will produce greater acceleration on the airplane with less mass. F=ma Even though the forces exerted on both planes are identical, the heavier airplane has more inertia and is not accelerated as much. Moral of the story: when it gets rough, slow down; and if you are light, slow down even more.
Excellent presentation. Bonanza-specific pilots may further review this in Eckalbar's book, "Flying the Beech Bonanza" were Eckalbar calls this diagram, appropriately, maneuver-gust envelope. . BTW, the curved portion of the diagram is exponential (quadratic) not logarithmic but that is a minor detail.
Actually, it's neither logarithmic nor exponential. It's polynomial, since lift increases with the square of airspeed. "Quadratic" was pretty close. 😁 Best regards, Martin
Worth noting is that the top corner of the Vg diagram is where aircraft with good control leverage reach their max instantaneous turn rate and begin to lose turn radius in the Vg diagram. Airplanes with poor control leverage are much more complicated, since the control inputs end up being too heavy past a certain speed.
Nice presentation. I've always had a bit of a problem with the adage that the "....airplane can stall at any airspeed...." While that's technically correct it doesn't help from a comprehension standpoint unless you add "depending on the g's or load conditions the aircraft is sustaining - or not sustaining - at the time. That's the purpose of the flight envelope presentation. I did my aerobatic training in sailplanes and it was very helpful in normal sailplane operations to understand the effect of the g-force component on stall speed. When spiraling in a tight thermal to gain altitude you can have the aircraft banked over 45 degrees, for starters, and 60 is not uncommon. That's where the aerobatics training comes in handy so you are adjusting pitch accordingly and not holding that nose up in a 45 degree bank to where you might otherwise hold it in a 30. In these situations, it's not usually dangerous but when you fall out of a thermal simply because you flubbed it - didn't keep the airspeed up (or the yaw string centered) where it needed to be it's frustrating and can cost you precious altitude - which is your bank account in sailplaning. In accumulating altitude (from thermals) in sailplanes, your primary job when you find lift and bank into it is to feel and keep pushing that bank angle to keep that pressure at the max - because that's your elevator hoist... but the more you bank, the more you need to lower than nose to stay in the air - so it's a balance. I've never done it myself, but I was riding with Les Horvath in a Grob and he did a 90 degree bank turn coming out of a dive that I think he held for maybe 30 degrees on the compass without stalling - because we had that airspeed - just rolling would have been easier, of course.
One thing worth mentioning.. There are some wierd and wacky planee out there. Some of them can have quite impressive sideslip maneuvers and also quite impressive drag generation. I'm not sure how many of them can actually bend or break from these things but it's probably not zero. I know in simulators you can design a plane that's really tough on the pitch axis and will disintegrate the moment you're doing much with sideslip. I think I made a flying wing in Kerbal + FAR that could do 10 G turns in pitch but the second you took your hand off the controls it would sideslip and, well, splash one flying wing.
Note that in many cases, there will be multiple different flight envelope barriers. stall AoA, max control authority, max control leverage, max G, thrust vector or propwash control authority, maximum stable AOA, different behavior in transonic or supersonic flight regime, etc.
I'm not sure it's wise to share it with student pilots. They are constantly devising new ways to kill the instructor - explaining to them precisely how to get outside the envelope would just encourage them :)
@@Shaneepe1 I was being facetious. All flight instructors are convinced that students participate in secret meetings where they plane new ways to kill the instructor. But that too is a joke. Of course it makes sense for student to watch that video.
I get the impression this guy knows a thing or two. I've always been perplexed by the idea that a gross weight airplane has a higher maneuvering speed than a lightly loaded airplane. I'll have to look for more videos from Martin.
Yes, it's counter-intuitive. The way to think of it is: maneuvering speed is a stall speed. And stall speeds are lower when the weight is lower. Now it all makes sense! - Martin
When flying the gust speed ( maneuvering speed ), we avoid over stressing the airplane from an inadvertent gust , at the max weight. It will stall before over stressing the plane. When flying at a lighter weight , flying the same maneuvering speed will allow the same gust to produce a load factor higher than 4g before stalling. We have a different Vg diagram for different weights/altitude combinations, but the POH normally gives us only one speed at max weight. So we must be prudent and understand that flying the same plane at a much lighter weight in turbulent conditions, unless flown at a slower speed, will over stress it (exceed the 4g limit) if the same turbulence is encountered.
Your educational videos are always highly appreciated (at least by me and from what I can tell many others too). Thank you for making them! I know you weren't teaching the information Martin (you were busy making another top notch video!), but maybe you or someone else here knows: I always thought Vg was best glide and Va was maneuvering speed (aka move the controls in any one direction at max gross and not break the plane speed), but is Vg the same as Va, or similar with some technical differences? Thanks and happy flying!
Hi Watashi. Best glide speed and maneuvering speed are different speeds. In all airplanes I have flown, maneuvering speed was higher than best glide speed. Best glide speed is based on aerodynamic performance (airspeed at which the highest lift-to-drag ratio is achieved), and has nothing to do with structural limits of the airframe (which is what defines maneuvering speed). Does that help? Best regards, Martin
Lieber Martin! Wirklich ein super Video! Ich frage mich, inwieweit es das Banken und den Angle of Attack mitberücksichtigt? Verstehe ich das richtig: ziehe ich über den critical angle of attack weiter so bin ich automatisch aus dem envelop weil im stall und daher auch links der Linie „all the plane can give“ oder links ausserhalb deren Verlängerung ABER dann auch immer über dem sich aus dem Diagramm ergebenden g Belastung ? Anders gesagt ich kreuze die (verlängerte) Linie, habe an deren Kreuzungspunkt die dortigen g und danach den stall? Ich hoffe das ist Dir nicht zu verwirrend! Besonders liebe Grüße aus Wien! Johannes👍😊✈️
Keep in mind that some more acrobatic aircraft actually have pilot removal levers rather than wing removal levers. If you G out, it doesn't really make much difference how strong the airframe is.
The myth of the danger of the downwind turn, Barry Schiff and your excellent high altitude orientation explanation is absolutely false. What we have here is a failure to communicate because we who work low every hour of every day depend on wind management to survive. I appreciate that you included low altitude orientation a bit in that ground speed increases in the downwind portion of the turn. The danger, for the crop duster, pipeline patrol pilot, gunship pilot, animal rancher or environmental worker counting animals, or any who work low is that the ground speed not only increases but that the radius of diameter of the ground track across the terrain also increases. With limitations in both vertical and horizontal space available, downwind turns to return to target are very dangerous. That is why crop dusters work from the downwind border and make every turn back to the next target (crop row) into a headwind component when the wind is significant. GPS has made race track more common and safe until the wind get up to 12 knots or so. Now every other turn (race track pattern) is a downwind turn. This turn takes twice the area and clearance of obstacles to make safely. Now lets communicate low altitude orientation pilots to high altitude orientation pilots. The downwind base to final turn which is now often so far from the airport that a level turn is desired, is also a dangerous high ground speed turn. This is not because of ground rush when the airplane is still a thousand feet up. It is because overshooting the centerline extended often happens and pilots generally aren't willing to allow the nose to go down naturally in all turns as the airplane was designed to do to prevent stall. Yes, we can add power but that increases the radius of the turn away from the centerline. The safer, wind management, turn is right base into a headwind component. The rule is an advisory at uncontrolled fields and such a rule would be dangerously poor wind management. Ground rush may be the culprit in the dangerous downwind turn near the ground in some cases. What about not hitting rising terrain or obstructions in the limited horizontal space available? Pilot steeped in high altitude orientation may just pull back on the stick to both turn with a shorter radius and to climb or at least stay level. Both maintaining altitude and climbing are deadly wrong in this situation. Decreasing radius of turn is appropriate but we have to have some training and practice in doing it appropriately. First anticipate the need to turn steeply. Secondly, if zoom reserve airspeed is available, pull the stick to climb wings level. Third, release all back pressure in a steeper than what you think is necessary to make the turn. This makes the turn of any bank angle a 1 g load on the wing, so no stall. Finally, level the wing prior to pull up headed toward the target. The reason to turn more than necessary initially is so that this level off and pull up need not to be rushed and we do not want to go over wires or obstructions with a wing low going into the crop row. So not everyone needs to be a crop duster. Since stall, base to final skidding turn spin, or slipping spin near the ground is generally fatal. Teaching crop dusting to second career CPLs and ATPs has convinced me that most experienced pilots lead aileron in turns and use too little rudder (slip) than too much rudder (skid.) So I don't believe in the danger of the skidding spin downwind base to final. I believe that stall there or anywhere in the pattern is generally fatal. Watch the videos of fatals. The stall generally happens at the beginning of the turn. Some spin low wing first (skid) but most spin high wing first (slip) or just stall. It really make no difference, nor does planned practice stall practice at altitude. So while not everyone needs to be a crop duster, every pilot needs to understand the reality of low altitude orientation, maneuvering flight, and such. We all takeoff and land every time we fly. The danger of the downwind turn is not a myth down there unless we have a headwind component on base to final and we have no terrain or obstructions around the airport. Only then are we saved by high altitude orientation, by unlimited vertical (wait here is a problem) and horizontal space available. By the way, when vertical space is limited airspeed and not altitude is life. Yes, that means neither Vx nor Vy are often appropriate. Low ground effect flight increases airspeed at no cost or danger to the pilot on long runways.
Very informative video. I was wondering why the "gust lines" of 50fps and 25fps are drawn as linear equations of a=mx+t with m representing the gust (so I assume). Wouldn't the gust have to be added or subtracted from the speed resulting in a parabolic relationship between speed and load factor?
if school was this interesting there would be a LOT more smarter people in this world... i still dont full understand but thats my point.. YOU HAVE MY ATTENTION !
I've flown for a long time. Never felt comfortable when there was turbulence. Here in Arizona, it is always there in the summer. Now I now why I haven't like it...... When it's bumpy, fly slower!
Worth noting that some aircraft have extremely poor performance in negative G. In fact, the entire flight envelope of something like a paramotor is in the positive G regime.
"Airspeed's gonna decrease" Uh... I wouldn't be so sure. If you're headed straight down like a brick, you've got 1 G accelerating you straight down like a brick. There are plenty of aircraft out there where 4 G on the stick would not drop the L/D below 4. In fact, I strongly suspect that Mustang is one of them if the speed of high enough.
Great video. However I believe there is a dangerous misinformation at 24:11. It is certainly NOT the case that the G-limit of the pilot will protect him from snapping of the wings by pulling the stick back *instantaneously*! Because the G-limit of a human depends on G and time. An untrained pilot can easily withstand 10G for 1 second. The airplane might not. So the wing will snap off before the pilot blacks out. See the blue dotted line on this graph for reference: en.wikipedia.org/wiki/G-force#/media/File:Human_linear_acceleration_tolerance.svg
Flying for me especially with my family along is to fly down the middle of my airplane’s performance. Not too fast, not too slow, not too high and not too low! I’m not a test pilot or an air show pilot.
At some point it might also be worth knowing the flight envelope of the pilot as well lol. If any part of "all the pilot can give" and "all the pilot can take" intersects with the aircraft's flight envelope...
I've been a pilot for a long time and have a lot of hours flying, but he might as well be speaking Greek. I tried to read "Stick and Rudder" by Langeaiesche but I couldn't understand most of it either. I've heard the statement that a plane can stall at any speed, but I have never understood why. I still don't.
Matt, go up with an instructor when you have a chance and ask for a demonstration of accelerated stall. You'll see in an instant what it means that a plane can stall at any speed. Regards, Martin
Could you possibly rename this video title v-n diagram to avoid confusion in accordance with regulations (14 CFR Part 23, Subsection 23.333) and industry standard? g is earth acceleration; n is the multiplier used in the diagram. Great video otherwise. thank you.
Whether it's correctly named by the conventions of physics or not, this video *is* referred to as the VG Diagram. We didn't come up with the name. And as Doug hints, "G" in this case may have more to do with gusts than with acceleration. Kind regards, Martin
Martin. I inly wanted to afford people interested in the topic a better chance of finding this video since it describes the load factor diagram used in the design and certification of aircraft in accordance with the relevant subsections of the FARs, sections 23.333 thru 23.341 (normal loads, gust loads, design speeds) and there the g axis is referred to as n, which is why I have only ever heard of it referred to as v-n diagram. I appreciate your videos. M.-A.
@@marc-andremuller1954 Thank you, Marc-Andre. I have added the following to the description of the video: "The V-g diagram is also referred to as the V-n (velocity versus load factor) diagram, as referenced in FARs 23.333 through 23.341." I appreciate the clarification.
@ Martin Pauly. Thank you Martin and thank you for your videos; I hope to apply some aspects of your operating lean of peak video once my new engine monitor is installed in a few weeks. safe flights!
I love this. For a brief moment this morning I feel really smart.
You can share this one with your CFIII students, Bryan! 😁
- Martin
Me too but then I woke up.👍
I was so confused about VG diagram. This is the best explanation out there. Thank you so much.
You are welcome, Captain Henny.
- Martin
Thank You Martin for bringing this to us and Thank You Doug for explaining something that is always a bit hazy for most pilots. Whenever we think there is absolutely nothing more we can possible learn, along comes a Doug and makes it all very clear for us. Fantastic! I once got a birthday gift from my wife and took a mock combat flight at Fullerton, CA at Air Combat USA. We pulled 4.5 G's which as a civilian pilot, that was the most I had ever experienced up to then. We flew the SIAI-Marchetti SF.260 which is a side by side trainer.
These guys can explain it better, than when I went to ground school.
Thanks.
I explained this to my kids a 'few' years ago. The positive G curve plots an infinite number of points where the wing can 'give' a specific G loading, at the specific plotted airspeed, without exceeding it's critical angle of attack. As you stated, there are other factors, such as asymmetrical wing loading, I think that the pilot manual I learned from glossed over this last factor, and only mentioned that it could be a factor. Also overlooked in that training is the very real difference in stall speed between lightly loaded aircraft and one that is maxxed out. More emphasis is put upon the 'wing will stall if it exceeds it's critical AOA, regardless of airspeed', without clearly stating that a heavier aircraft will require more AOA at a given airspeed, to continue level flight. It's all in the wording. Thanks for this excellent video.
All good points. I would add that heavier aircraft will require more AOA at a given airspeed not just to continue level flight, but even to continue a sustained climb or descent (with a constant vertical speed).
- Martin
Excellent! Owned and flew a Super Decathlon for several years. Took aerobatic instruction from a couple of professionals and never had this explained to me. I flew all the maneuvers listed in the POH and never had to exceed 3.5 g's. I distinctly remember and the plane showed me how adding g would increase turn rate and limit airspeed. Never got in a situation where i needed to pull 4+ g to avoid the ground and learned something new from this discussion. Really enjoyed the video, thanks.
Thanks for the feedback, Don!
- Martin
It was a pleasure meeting and speaking with you. It also felt good speaking German!
Likewise 👍
I've never seen those concepts explained so concisely and explained exactly how all the numbers were arrived at. I feel a lot smarter having seen that. Thanks for sharing it.
Glad you found it helpful, Martin!
- Martin
One of my all-time favorite channels... Martin and Doug are treasures to GA!
Always Nice To See Captain Doug and Captain Martin Working Together !
More Than Important To Know All of That, And, If Possible, To Have It All In The Blood Stream, Naturally, THROUGH TRAINING !
I Met a Captain a Long Ago (Captain Ferreira From TransBrasil Airlines - RIP) Who, In The Early 60's,
Did His Aviation Training, Which Included Soaring Flights and Aerobatics,
What is The Focus of Captain Doug’s Class.
To Acknowledge in Advance What The Plane Is Capable Of, As Well As,
To Aknowledge Upset Maneuvers and To Know What To Do In Case They Happen Unintentionally or Inadvertently
To Prevent Bad Reactions As "Startle Effect", "Tunel Vision", Etc., What Could Cause a Serious, However Avoidable, Accident.
By The Way, In The Multi Engine Training Episode (The Drill - Part 1),
Captain Doug Said :
" We'll Beat This In Your Brain At The Same Place In Your Brain Where Mary Had a Little Lamb Exists ..." !
In The End, Like Captain Doug Said :
To Be a Better Pilot !
Many Thanks !
Best Regards !
Ed
Tremendous teacher Doug. Thank you for bringing this to us Martin. I would like to add asymmetric, or rolling pullouts can affect the GA pilot and here is how. The initial concern in the rolling pull is structural limit, as speed decreases you will enter the slow speed regime and one wing will stall first. The high wing will have a higher AOA and therefore stall creating a un commanded roll in the opposite direction. Very often you see this in crash footage, usually a security camera near a crash site. I belief it’s the reason most fatal GA crashes occur. Not keeping the wings level nearing stall speeds with GLoad, ie pulling away from terrain.
Thank you again. Sharing this is important for us all
Yes, you bring up localized AOA which can be a big surprise to the uninitiated. I'll cover that in another video in the future.
- Martin
What a great educational video. I searched "What determines Vne" and it popped up, and learned so much more than just the 25 and 50fps gust rules.
Glad we could be of help, Dan.
- Martin
Very interesting conversation and I'm glad you shared this with us all. Thank you for putting these together for us all to learn more Martin.
Glad you found it useful, Kevin.
- Martin
Omg I just wanna say thank you. This has been the best video regarding the Vg diagram I have ever seen. The maneuvering speed illustration of how it decreases with a lighter wight was just insane. So many people explain it in a weird way but seeing that was crazy. Gonna rewatch it several times so I can teach this well
Glad you enjoyed it, and thanks for helping spread the word on these concepts.
- Martin
Thank you gentlemen! This is excellent. I spent a lot of time trying to understand weight impacts on the envelope during my training, but never really go it. It always seemed backwards to me. I get it now. It's crazy that just adding the words "give" and "take" can totally unlock a concept. That V^2 will get you... These lessons you guys are recording are incredible. A lot of training seems to be memorizing, not deep understanding. You and Doug are changing that. Please keep it up, the GA community is grateful!
So refreshing to see calm and educated content.❤
Easily the best aviation video I’ve seen on RUclips.
Thank you - happy to hear you found it valuable.
- Martin
I have started training recently and will have to review this again in several weeks and several months.
No rush - this is one you should come back to in a year or two. Then it will help answer questions which at this moment you may not have wondered about yet.
- Martin
I have watched a multitude of your videos over the years and continue to be grateful for the consistent indeapth dive. Thanks again for the content.
You are very welcome, Farayi.
- Martin
This is truly excellent. Doug is really smart and an excellent teacher. I’ve done EMT or upset recovery and we talked about many of these things.
I have to admit that I never knew exactly where Vno comes from.
Glad we could help!
- Martin
One of the best vids I've come across that might keep me safe as a GA pilot. One thing that really got my attention is the first statement that Doug made about RV and Experimental aircraft owners in general, and their lack of understanding of this graph. I am considering purchasing an RV8, and have wondered about how to fly acro in them, even as the G limits are clearly stated.
I have formal acro instruction in a Decathlon, but if I do purchase a -8, I want to be damn sure I am flying/maneuvering the plane well within its limits.
This vid was very helpful, although I will have to watch it again to be certain that I fully understand conceptually this Vg graph.
Thanks for doing these videos.
Glad to hear this video was useful for you, and good luck finding your RV8!
- Martin
Great video Martin. As a pilot, engineer, and builder of a single seat aerobatic airplane, I found this really interesting and informative!
Thank you, George - glad you enjoyed it.
- Martin
Very valuable video. Doug has a really great way of making the difficult to grasp seem so understandable. I particularly liked the explanation of the "rolling g" issue, because I knew of this for years, but never really understood the reason why. Great service to the aviation community Doug and Martin
Thank you for the kind words, Dave.
- Martin
Thanks Martin, I learned some things. I'll use this video when explaining Va vs weight to students. It makes a lot of sense this way. Keep making great content.
It's also worth noting that when recovering from an unusual attitude, rolling first and then pulling is more effective because roll rate decreases with G loading. Unload the wing, roll level, then pull.
Great video! I work as a pilot in skydive ops for a living, so I find myself daily at the edge of the envelope. I believe it is crucial for anyone operating in similar ops to be familiar with the structural and aerodynamic limit, as the "do not exercise full flight control surface deflection above Va" is simply wrong and can sometimes be dangerous.
E.g. when pulling out of a dive at 0 deg pitch attitude you're very likely to be within the limit load factor margin and could apply full elevator low in order to maintain level flight and avoid stalling.
Thats a lot to take in before coffee! Tks Martin.
Yes. 😁
- Martin
Super interesting, Martin. Thanks for putting this together. And great find in Doug -- a wealth of information. He has a way of imparting very complicated data in a way that simple(ton) people like me can understand(ish). Thanks again, Martin.
Thank you for the kind words, Jeff.
- Martin
Wow!
The best lesson on the Vg diagram
This quickly turned into a quiz for Martin. I feel your pain.
Not painful at all. Doug's (excellent) teaching style includes a lot of questions to guide the discussion and keep the student engaged and alert. It's always a pleasure to sit down with Doug and learn from him.
- Martin
Thanks for this video, Martin, and thanks to Doug for the explanation of VG diagram. Well explained. Love it!!!
Glad you enjoyed this presentation!
- Martin
I'm currently working on my PPL theory, and this video came at the perfect time! Thank you Doug for explaining it and thank you Martin for getting Doug on video!
Glad it's helpful for you Ralf. Good luck for completing your PPL.
- Martin
Doug is such a good teacher.
Agree 100%.
- Martin
Great explanation. Definitely got to watch this multiple times. Thanks for another great video.
Thanks for the kind feedback, Eddie!
- Martin
Hey Martin, I love hearing from Doug. It's spooky how he and I think and teach the same way...
I learned this in ground school, I understood it with you Paul, Thank you
Excellent discussion, thanks Martin and Doug!
Glad you enjoyed it!
- Martin
That's a great and easy to understand explanation, thank you very much.
Thanks!
- Martin
Why does maneuvering speed decrease with weight? It's all about angle of attack.
Take two identical normal category airplanes flying at the published Va: one is very light, one heavily loaded at max gross.
Regardless of their weight, both airfoils will stall at the same critical angle of attack.
The light airplane flies at a lower AOA for this given speed, compared to the heavy airplane which must fly at a relatively higher AOA at all times to produce more lift.
So the heavier airplane (for a given speed) is always closer to a stall.
If the pilot of the heavier airplane yanks back on the controls (or, encounters some turbulence, which is essentially the same thing), there is exactly enough AOA remaining for the wing to generate +3.8G's just as the critical AOA is reached.
The stall acts as an aerodynamic safety valve which releases the pressure, protecting the airplane from itself, returning it to ~1G.
But the light airplane has much more AOA left to play with, and therefore much more potential to generate higher G loads.
If the pilot of the light airplane doesn't want to bend or break something, he must 1st slow down to the weight-corrected maneuvering speed, thereby increasing his AOA and lowering his potential to make G.
You can calculate Va for any weight by multiplying the Va at max gross by the square root of the weight ratio. (actual weight/max gross)
Additionally, it's the _acceleration_ which produces stress on the airframe and the G's which you feel on your body.
Force = mass * acceleration
Imagine a 30fpm vertical gust of wind exerting the same force on those two airplanes: one light, one heavy.
The same force will produce greater acceleration on the airplane with less mass. F=ma
Even though the forces exerted on both planes are identical, the heavier airplane has more inertia and is not accelerated as much.
Moral of the story: when it gets rough, slow down; and if you are light, slow down even more.
Excellent presentation. Bonanza-specific pilots may further review this in Eckalbar's book, "Flying the Beech Bonanza" were Eckalbar calls this diagram, appropriately, maneuver-gust envelope. . BTW, the curved portion of the diagram is exponential (quadratic) not logarithmic but that is a minor detail.
Actually, it's neither logarithmic nor exponential. It's polynomial, since lift increases with the square of airspeed. "Quadratic" was pretty close. 😁
Best regards,
Martin
@@martinpauly yes, sorry I had virus curves on my mind. It is exactly quadratic. Quadratic function is a polynomial.
Best explanation on RUclips!
Thank you, Sir!
- Martin
Thank you for making this video, Martin. Greetings from Argentina.
Thank you, Juan. Glad you found it useful.
- Martin
Worth noting is that the top corner of the Vg diagram is where aircraft with good control leverage reach their max instantaneous turn rate and begin to lose turn radius in the Vg diagram.
Airplanes with poor control leverage are much more complicated, since the control inputs end up being too heavy past a certain speed.
Wow! Great teaching! Thanks Martin and Doug👍
Glad you enjoyed it, Justin!
- Martin
Very informative even though I'm not a pilot. You never know when it could be useful. Thanks Martin.
Thanks, Bill.
- Martin
Perfect explanation! Thanks for sharing this!
FANTASTIC video, really enjoyed it
Thank you, Jason.
- Martin
very intuitive and understandable explanation
Thank you, Louis.
- Martin
Thanks both of you all The from sweden 👍👍 that make sense
Awsome 💗💗
Thank you, Frederick. Greetings to you from Iowa.
- Martin
Wow! Saving this to watch a few more times. Great teaching! Thank you.
Nice presentation. I've always had a bit of a problem with the adage that the "....airplane can stall at any airspeed...." While that's technically correct it doesn't help from a comprehension standpoint unless you add "depending on the g's or load conditions the aircraft is sustaining - or not sustaining - at the time. That's the purpose of the flight envelope presentation. I did my aerobatic training in sailplanes and it was very helpful in normal sailplane operations to understand the effect of the g-force component on stall speed. When spiraling in a tight thermal to gain altitude you can have the aircraft banked over 45 degrees, for starters, and 60 is not uncommon. That's where the aerobatics training comes in handy so you are adjusting pitch accordingly and not holding that nose up in a 45 degree bank to where you might otherwise hold it in a 30. In these situations, it's not usually dangerous but when you fall out of a thermal simply because you flubbed it - didn't keep the airspeed up (or the yaw string centered) where it needed to be it's frustrating and can cost you precious altitude - which is your bank account in sailplaning.
In accumulating altitude (from thermals) in sailplanes, your primary job when you find lift and bank into it is to feel and keep pushing that bank angle to keep that pressure at the max - because that's your elevator hoist... but the more you bank, the more you need to lower than nose to stay in the air - so it's a balance. I've never done it myself, but I was riding with Les Horvath in a Grob and he did a 90 degree bank turn coming out of a dive that I think he held for maybe 30 degrees on the compass without stalling - because we had that airspeed - just rolling would have been easier, of course.
Excellent explanation! Thank You
My pleasure, Adam.
- Martin
Great content Martin! Thanks for bringing this to us!
My pleasure, Jared.
- Martin
This is great 👍 Awesome teaching job gentlemen, thanks
Thanks - glad you enjoyed it!
- Martin
Very interesting. Thanks for sharing this important info.
Thank you, Tim!
- Martin
This is magnificent, great wealthy video, very informative, thanks a lot for sharing the video, all the best.
Thank you, glad you enjoyed it.
- Martin
THANK YOU. An excellent presentation!
Thank you, Mark.
- Martin
Thank you, Martin! Great video.
Thank you, Jack.
- Martin
Best explanation ever!! Thanks so much.
Thank you, Chad. Glad you found it valuable.
- Martin
One thing worth mentioning..
There are some wierd and wacky planee out there. Some of them can have quite impressive sideslip maneuvers and also quite impressive drag generation. I'm not sure how many of them can actually bend or break from these things but it's probably not zero. I know in simulators you can design a plane that's really tough on the pitch axis and will disintegrate the moment you're doing much with sideslip. I think I made a flying wing in Kerbal + FAR that could do 10 G turns in pitch but the second you took your hand off the controls it would sideslip and, well, splash one flying wing.
Thankyou Martin and Doug.
* Envelope of aerodynamic force.
🤯🌴
Note that in many cases, there will be multiple different flight envelope barriers. stall AoA, max control authority, max control leverage, max G, thrust vector or propwash control authority, maximum stable AOA, different behavior in transonic or supersonic flight regime, etc.
Great info. Well explained.
Thank you, Stephen.
- Martin
This was an awesome explanation
Thank you, Fernando.
- Martin
Great review, thanks Martin!
Thanks, Christine.
- Martin
Fantastic video. Thank you!!!
Thanks, John.
- Martin
Super Interesting! Can we have a weekly series please? This imho would benefit even student pilots.
student pilot here... -consider me benefited!
I'm not sure it's wise to share it with student pilots. They are constantly devising new ways to kill the instructor - explaining to them precisely how to get outside the envelope would just encourage them :)
@@LimeyTX I hear your point but for me it just makes me less nervous not more adventurous....
@@Shaneepe1 I was being facetious. All flight instructors are convinced that students participate in secret meetings where they plane new ways to kill the instructor. But that too is a joke.
Of course it makes sense for student to watch that video.
@@LimeyTX understood I will lighten up :)
outstanding video, thanks.
Thank you.
- Martin
Wonderful! Thank you very much!
Our pleasure, Andrius.
- Martin
This is great info please keep it up
Thanks, Matthew.
- Martin
This is a really good video.
Thank you!
- Martin
Great Talk! thanks Martin!
Thank you, Kyle.
- Martin
That was amazing! I learned a lot. Thanks!
Glad to hear, Shane.
- Martin
Great Video
Thank you, Chad.
- Martin
I get the impression this guy knows a thing or two.
I've always been perplexed by the idea that a gross weight airplane has a higher maneuvering speed than a lightly loaded airplane.
I'll have to look for more videos from Martin.
Yes, it's counter-intuitive. The way to think of it is: maneuvering speed is a stall speed. And stall speeds are lower when the weight is lower. Now it all makes sense!
- Martin
When flying the gust speed ( maneuvering speed ), we avoid over stressing the airplane from an inadvertent gust , at the max weight. It will stall before over stressing the plane. When flying at a lighter weight , flying the same maneuvering speed will allow the same gust to produce a load factor higher than 4g before stalling. We have a different Vg diagram for different weights/altitude combinations, but the POH normally gives us only one speed at max weight. So we must be prudent and understand that flying the same plane at a much lighter weight in turbulent conditions, unless flown at a slower speed, will over stress it (exceed the 4g limit) if the same turbulence is encountered.
amazing like always
Thank you!
- Martin
Love the ground school gentlemen!
Thanks, Brian. And the classroom isn't too shabby either, is it? 😁
- Martin
@@martinpauly cripes o mighty is a nice back drop to be around!
Hi Martin, great videos-thanks! Very nice to meet you at SNF in the Avidyne tent outside. Keep up the great videos and if you stop by KVYS look me up.
Thank you, Kev - I hope you had a great time in Lakeland!
- Martin
This helped me understand why the never exceed speed on turbines is annoyingly slow. That's why you fly them high.
Exactly, Charlie.
- Martin
Your educational videos are always highly appreciated (at least by me and from what I can tell many others too). Thank you for making them!
I know you weren't teaching the information Martin (you were busy making another top notch video!), but maybe you or someone else here knows: I always thought Vg was best glide and Va was maneuvering speed (aka move the controls in any one direction at max gross and not break the plane speed), but is Vg the same as Va, or similar with some technical differences?
Thanks and happy flying!
Hi Watashi. Best glide speed and maneuvering speed are different speeds. In all airplanes I have flown, maneuvering speed was higher than best glide speed. Best glide speed is based on aerodynamic performance (airspeed at which the highest lift-to-drag ratio is achieved), and has nothing to do with structural limits of the airframe (which is what defines maneuvering speed).
Does that help?
Best regards,
Martin
Lieber Martin!
Wirklich ein super Video!
Ich frage mich, inwieweit es das Banken und den Angle of Attack mitberücksichtigt? Verstehe ich das richtig: ziehe ich über den critical angle of attack weiter so bin ich automatisch aus dem envelop weil im stall und daher auch links der Linie „all the plane can give“ oder links ausserhalb deren Verlängerung ABER dann auch immer über dem sich aus dem Diagramm ergebenden g Belastung ? Anders gesagt ich kreuze die (verlängerte) Linie, habe an deren Kreuzungspunkt die dortigen g und danach den stall?
Ich hoffe das ist Dir nicht zu verwirrend!
Besonders liebe Grüße aus Wien!
Johannes👍😊✈️
Nice
Keep in mind that some more acrobatic aircraft actually have pilot removal levers rather than wing removal levers. If you G out, it doesn't really make much difference how strong the airframe is.
Bravi!
The myth of the danger of the downwind turn, Barry Schiff and your excellent high altitude orientation explanation is absolutely false. What we have here is a failure to communicate because we who work low every hour of every day depend on wind management to survive. I appreciate that you included low altitude orientation a bit in that ground speed increases in the downwind portion of the turn. The danger, for the crop duster, pipeline patrol pilot, gunship pilot, animal rancher or environmental worker counting animals, or any who work low is that the ground speed not only increases but that the radius of diameter of the ground track across the terrain also increases. With limitations in both vertical and horizontal space available, downwind turns to return to target are very dangerous.
That is why crop dusters work from the downwind border and make every turn back to the next target (crop row) into a headwind component when the wind is significant. GPS has made race track more common and safe until the wind get up to 12 knots or so. Now every other turn (race track pattern) is a downwind turn. This turn takes twice the area and clearance of obstacles to make safely.
Now lets communicate low altitude orientation pilots to high altitude orientation pilots. The downwind base to final turn which is now often so far from the airport that a level turn is desired, is also a dangerous high ground speed turn. This is not because of ground rush when the airplane is still a thousand feet up. It is because overshooting the centerline extended often happens and pilots generally aren't willing to allow the nose to go down naturally in all turns as the airplane was designed to do to prevent stall. Yes, we can add power but that increases the radius of the turn away from the centerline. The safer, wind management, turn is right base into a headwind component. The rule is an advisory at uncontrolled fields and such a rule would be dangerously poor wind management.
Ground rush may be the culprit in the dangerous downwind turn near the ground in some cases. What about not hitting rising terrain or obstructions in the limited horizontal space available? Pilot steeped in high altitude orientation may just pull back on the stick to both turn with a shorter radius and to climb or at least stay level. Both maintaining altitude and climbing are deadly wrong in this situation. Decreasing radius of turn is appropriate but we have to have some training and practice in doing it appropriately. First anticipate the need to turn steeply. Secondly, if zoom reserve airspeed is available, pull the stick to climb wings level. Third, release all back pressure in a steeper than what you think is necessary to make the turn. This makes the turn of any bank angle a 1 g load on the wing, so no stall. Finally, level the wing prior to pull up headed toward the target. The reason to turn more than necessary initially is so that this level off and pull up need not to be rushed and we do not want to go over wires or obstructions with a wing low going into the crop row.
So not everyone needs to be a crop duster. Since stall, base to final skidding turn spin, or slipping spin near the ground is generally fatal. Teaching crop dusting to second career CPLs and ATPs has convinced me that most experienced pilots lead aileron in turns and use too little rudder (slip) than too much rudder (skid.) So I don't believe in the danger of the skidding spin downwind base to final. I believe that stall there or anywhere in the pattern is generally fatal. Watch the videos of fatals. The stall generally happens at the beginning of the turn. Some spin low wing first (skid) but most spin high wing first (slip) or just stall. It really make no difference, nor does planned practice stall practice at altitude. So while not everyone needs to be a crop duster, every pilot needs to understand the reality of low altitude orientation, maneuvering flight, and such. We all takeoff and land every time we fly. The danger of the downwind turn is not a myth down there unless we have a headwind component on base to final and we have no terrain or obstructions around the airport. Only then are we saved by high altitude orientation, by unlimited vertical (wait here is a problem) and horizontal space available. By the way, when vertical space is limited airspeed and not altitude is life. Yes, that means neither Vx nor Vy are often appropriate. Low ground effect flight increases airspeed at no cost or danger to the pilot on long runways.
OUTSTANDING however I hit Vne to -G towards final# reply necessary :-)
Thank you, Bernard.
- Martin
Very informative video. I was wondering why the "gust lines" of 50fps and 25fps are drawn as linear equations of a=mx+t with m representing the gust (so I assume). Wouldn't the gust have to be added or subtracted from the speed resulting in a parabolic relationship between speed and load factor?
Thanks, Johann. I do not know the answer to your question, I'm afraid - I hope Doug will see this and chime in here.
Regards,
Martin
if school was this interesting there would be a LOT more smarter people in this world... i still dont full understand but thats my point.. YOU HAVE MY ATTENTION !
Well, if we managed to make you curious, that's half the battle!
- Martin
I've flown for a long time. Never felt comfortable when there was turbulence. Here in Arizona, it is always there in the summer. Now I now why I haven't like it...... When it's bumpy, fly slower!
You got it! 👍
- Martin
Worth noting that some aircraft have extremely poor performance in negative G. In fact, the entire flight envelope of something like a paramotor is in the positive G regime.
"Airspeed's gonna decrease"
Uh... I wouldn't be so sure. If you're headed straight down like a brick, you've got 1 G accelerating you straight down like a brick. There are plenty of aircraft out there where 4 G on the stick would not drop the L/D below 4. In fact, I strongly suspect that Mustang is one of them if the speed of high enough.
Great video. However I believe there is a dangerous misinformation at 24:11. It is certainly NOT the case that the G-limit of the pilot will protect him from snapping of the wings by pulling the stick back *instantaneously*! Because the G-limit of a human depends on G and time. An untrained pilot can easily withstand 10G for 1 second. The airplane might not. So the wing will snap off before the pilot blacks out. See the blue dotted line on this graph for reference: en.wikipedia.org/wiki/G-force#/media/File:Human_linear_acceleration_tolerance.svg
Very good Martin
Thank you, Charlie - glad you enjoyed this one.
- Martin
Flying for me especially with my family along is to fly down the middle of my airplane’s performance. Not too fast, not too slow, not too high and not too low! I’m not a test pilot or an air show pilot.
If the curve is defined by that squared relationship between lift and airspeed - it can't be logarithmical as stated.
At some point it might also be worth knowing the flight envelope of the pilot as well lol. If any part of "all the pilot can give" and "all the pilot can take" intersects with the aircraft's flight envelope...
Yeah that was good.
Ask any ag pilots to explain it!
Yup. Planes don't stall at a speed. They stall at an angle of attack.
For a constant flap setting obviously.
I've been a pilot for a long time and have a lot of hours flying, but he might as well be speaking Greek. I tried to read "Stick and Rudder" by Langeaiesche but I couldn't understand most of it either. I've heard the statement that a plane can stall at any speed, but I have never understood why. I still don't.
Matt, go up with an instructor when you have a chance and ask for a demonstration of accelerated stall. You'll see in an instant what it means that a plane can stall at any speed.
Regards,
Martin
Could you possibly rename this video title v-n diagram to avoid confusion in accordance with regulations (14 CFR Part 23, Subsection 23.333) and industry standard? g is earth acceleration; n is the multiplier used in the diagram. Great video otherwise. thank you.
See the video again at 14:45!
Whether it's correctly named by the conventions of physics or not, this video *is* referred to as the VG Diagram. We didn't come up with the name. And as Doug hints, "G" in this case may have more to do with gusts than with acceleration.
Kind regards,
Martin
Martin. I inly wanted to afford people interested in the topic a better chance of finding this video since it describes the load factor diagram used in the design and certification of aircraft in accordance with the relevant subsections of the FARs, sections 23.333 thru 23.341 (normal loads, gust loads, design speeds) and there the g axis is referred to as n, which is why I have only ever heard of it referred to as v-n diagram. I appreciate your videos. M.-A.
@@marc-andremuller1954 Thank you, Marc-Andre. I have added the following to the description of the video: "The V-g diagram is also referred to as the V-n (velocity versus load factor) diagram, as referenced in FARs 23.333 through 23.341." I appreciate the clarification.
@ Martin Pauly. Thank you Martin and thank you for your videos; I hope to apply some aspects of your operating lean of peak video once my new engine monitor is installed in a few weeks. safe flights!