A blast shield on an aircraft carrier does not increase jet performance, as jet engines propulsion is based on momentum. It's just there to protect other aircraft. I like your explanation of the various climb speeds and their consequence for obstacle and terrain clearance.
Thanks. You are correct, I don't think jet performance plays any factor in the use of a jet blast door. And when using a catapult, it wouldn't even make sense to use it to increase thrust (as the catapult does the work). Thanks for the correction. But it will increase thrust nonetheless. The blast door redirects air up at a fairly high angle, and in turn resists the free flow of air backwards horizontally (the direction it is spewed out of the engine). That resistance of free flow increases pressure at the point the air gets redirected. The point of the jet blast door is to shield what's behind it. Without it, if a person was behind the jet as it powers up, they would likely be blown off deck, correct? That's because of the force enacted on the person. If you push against a wall, the wall pushes back just as hard. So both in terms of fluid dynamics and newton's 3rd law, thrust will be increased. I don't know how much additional thrust is provided though.
@@LetsGoAviate Actually, that increase in exhaust nozzle pressure force is adversely compensated for by a decrease in exhaust gas momentum (because exhaust gas velocity decreases when exhausting to a higher pressure). At best you'd break even, but a small decrease in overall thrust is actually more likely as the nozzle exit plane pressure and momentum tend to not trade exactly one for one and momentum is the bigger driver. You can do a CFD simulation and prove it to yourself by integrating pressure, friction, and momentum forces over your control volume.
What is astonishing is how many pilots disregard the POH despite the fact that the designers have studied all the possible scenarios and the manual is a compilation of their knowledge and experience. Bad habits and incorrect reflexes, especially if acquired from poor instruction, can eventually lead to disaster. If the engine fails at an early stage of climb out, the natural reaction to keep the nose up is fatal. My CFI would never let anyone solo until they had the acquired the reflex to lower the nose and preserve the airspeed.
You have a good CFI. If that engine starts sputtering, or even dies immediately, studies have shown that many pilots take about 3-4 seconds to realize what has just happened. Good CFIs train their "students" to get the nose done immediately, even if it creates negative Gs while doing so.
Early/previous training in gliders is also very helpful as students are trained at an early stage to respond instinctively to a cable break by pitching down for airspeed.
My old plane won't make book numbers, and I'm not alone in this. (Comes closer with the Powerflow exhaust, GAMI injectors and K+N airfilter). The reason: It's overweight. I have scales in my shop. For planning purposes, I weighed it with interior and all insulation removed, no oil, no fuel, no avionics, it was still 100 pounds above Cessna's claimed numbers!
@@cujet That is very interesting. Do you have the same wheel skirts as the original? Have they been removed? Wheel skirts reduce drag, as you know. Have you added any new parasite drag components? It's possible either your scales or Cessna's scales weren't calibrated against a standard weight. But still, one wouldn't think that 100 lbs. would not make much of a difference in the book numbers. My buddy's Mooney M20C consistently trues out between 145-147 kts at higher altitudes whether it's at gross weight or much lighter.
I got my PPL in Texas in a C152II Aerobat. Two grown men in a tiny 152 in 90+ degree heat and 1200'+ field elevation? Yeah, we used ground effect a lot.
Ground effect acceleration is very helpful for an unpaved runway. Wet grass, mud, etc is minimized and safe climb speed achieved just after lifting off.
It is my default on every takeoff until Vcc or when an obstruction requires pitch up to just clear. Airspeed, and not altitude, is life until high enough to recover from inadvertent stall.
This. Get the wheels off the grass for max acceleration without the drag from the wheels. It gets you to a safe climb speed with less runway behind you.
Isn’t this literally the definition of a soft field landing? Lift the nose and get off the ground as soon as possible, push forward and use ground effect to accelerate to Vx or even Vy then climb. Of course, one might want to remove flaps to get to a higher Vy but removing float close to the ground is not worth the risk.
@@lordcraycray2921 Vy is the math most up for time, but that doesn't make it safer than using runway still ahead, level in low ground effect, until fast enough to maneuver safely regardless of what happens next. Vx or Vy are not safe airspeeds when too low to recover from an inadvertent stall which is usually fatal.
After a scary uphill takeoff at the Spring Hill 70N airport in Pennsylvania, I have three suggestions: 1) Never fly to an airport named "Hill", 2) Remember that sometimes you should (must!) takeoff downwind instead of straight towards a steep hill, 3) Memorize your plane's Vx speed because you might need it to climb a hill.
Great video. I used to live at at KAXX (Angel Fire, NM) where field elevation is 8,380 feet and DA is typically >10,000’. The runway was long (8,900 feet) and I would advocate for ground effect assisted takeoff all the time. With the long runway, staying in ground effect after the wheels leave the ground somewhere around 2,000 feet for most NA GA planes, gave pilots the ability to just pull back power and land easily if there was a need to abort. My personal way of doing this in my Turbo Saratoga was to start with a static takeoff, trim down slightly, one notch of flaps. Stop at the end of the runway, spin up the engine to 36” of manifold pressure, check all gauges, release the brakes. Lift off at 76 knots and accelerate in ground effect until I reach the edge of the white arc (max flap speed), and then I pop in the 2nd notch of flaps, which is 20 degrees for me, which also happens to be my “maximum lift flap settings” (which would be a good video to do). With the slight nose down trim, just putting in the 20 degrees of flaps leads to a 1000 rpm climb rate, at a good airspeed, and I do not even have to change my yoke pressure to do it. Once I get to 1500 feet AGL, I can pull the turbocharger out of the engine, drop the flaps, and have sufficient altitude to be able to make a safe landing if I needed to. Glad you did this video, you stated the obvious very nicely (nicer than me according to my wife) when you said a “ground effect assisted takeoff takes a focused and competent pilot”. My wife flies with me all the time, works my checklists with me, and works the radio. We always observe sterile cockpit until we reach 3000 feet AGL. If you are interested, I did a safety video about the nuances of flying in and out of Angel Fire, and I briefly mention the ground effect assisted takeoff. You can find that video here. ruclips.net/video/AmrAX7tSvvQ/видео.htmlsi=ef97HOAyuZekBf5e
In a Cessna 182, a cruise climb is done using 90% power setting. Full power suggested use is up to 30 seconds for cooling reasons. A low wing plane flying in ground effect works rather well. In my Cessna 150, I hold close to the runway until aproaching VY because of the low available power. So, not only the terrain situation matters but the type of aircraft too.
Great video! Standard pilot training is to use VX to clear of obstacles and then VY for climb out. Advantage of VX is that if there is an issue with climb you find out early and may still have available runway to land on. In the event of engine failure you need to get to best glide as fast as you can. For example, in Cessna 172 VX is 56, Best glide is 65 and VY is 76 so +10 knots for VX or -10 knots for VY. On cold days my favorite is Ground assisted acceleration and then a pull up as it feels like you are in a way better plane than you actually are. I wouldn’t use cruise climb for anything other than cruise climb. Good way to keep the engine cool on those long climbs to altitude if ATC permits.
Just put a Blue Line on full gross Vglide speed. Vx is a few knots under, Vy a few knots over depending on weight. We had them on all the 1990's airplanes we flew at our flight school. We had the best students flying in crosswinds when the 2 other flight schools could not fly. Laggards they were..
This video is the first time that I have heard the term “Vcc.” Even an article on Pilot Institute dated October 9,2023 doesn’t use this term. Interesting video. Thanks!
Excellent video. In the UK in the 80s a microlight aircraft was developed that used ground effect as its standard take off procedure. The Chevron was underpowered, to keep within weight regulations, and so was developed to utilise this phenomenon
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When climbing at Vx the windshields angle of incident is shallowest thus reducing the forces in the event of a bird strike. During times of high bird activity at my home airport I often choose a Vx climb to get up quickly and also lessen the chance of eating bird mixed with shards of acrylic. It’s difficult to transition to best glide speed when half of your face is missing.
Just one addition. If you have a BRS, it's always Vy until that BRS becomes available, of course after clearing obstacles. I usually have ample runway left accelerating to Vy in ground effect and clearing obstacles without having to climb with Vx. The "CAPS available" callout feels good 😊
"Best" answer: it depends. Love it and, I agree. Looking into POHs, Vcc is seldom given. There are some with graphs that show the change in Vy and Vx speeds with altitude. I guess you could halve the difference in cruise speed and Vy and use that?
For the crop duster it is not a number in the POH. Energy is life and ground effect is free energy. Roll on the wheels, less energy. Pitch up while slow and lots of ground effect left, less energy. Level in low ground effect so long as runway ahead, more energy. Down drainage egress is potential energy of altitude you didn't have to give up any airspeed for, more energy. Again free energy. In small trainers and crop dusters, ground effect, down drainage, thermal lift, and orographic lift often equaled 50% of total energy available. In really rough air or mountain wave, natural energy far exceeds fuel energy. And it is free.
I had power fail in a Tomahawk turning crosswind at 600 feet. I grabbed controls from the student, stuffed nose down to 80 kts, turned and landed on cross alternate runway. Always glide higher than best glide, you have something to play with.
I would think if you are climbing out at Vcc and have an engine failure, you should in fact climb a little to gain altitude until you slow to Vglide so that you now have the highest possible altitude and are configured at the best glide speed for maximum distance possible.
That's true, because that way less energy is lost to drag. However it's safer to have reflexes to pitch down than up. If you have the brain space to think in that instance, then pitch up for best glide after the reflex.
Yeah. I was thinking that exact point. “Am I really going to be able to think all that through in the moment?”I hope I’d actually immediately pitch down, but then adjust after. I think I’ll take a little loss in energy as long as pitching down is a reflex!
@@arpeltier My engine failures were six second deals. I always had airspeed from ground effect on takeoff or in the spray swath in the field. This allowed me to maneuver as necessary to what looked best in the very near hemisphere from a couple hundred feet at most. No pitch down is necessary with zoom reserve airspeed. An energy management 1 g turn at any bank angle is available. Pitch up wings level, turn to a good site while releasing all back pressure on the stick, this allows the nose to go down as designed to prevent stall, add full flaps and forward slip (I was almost always high and fast to what I could see from down low), and touchdown slowly and softly in the beginning of the landing zone. Flying all the way to the crash works best. What to do is pretty obvious so not a lot to think through in seconds...no moment available.
Great video, thanks! I own and fly a Mighty Thunder Cardinal 177RG (a little joke, as there is no thunder and no might). Accelerating in true ground effect is really too low for my comfort level, but I've tried Vx, Vy and Vzoom, albeit above ground effect, and noted my altitude and speed in the pattern at different points. Flying out of F45, I like to get over 2500', to avoid the adjacent Class D. All methods will result in about 500 feet of altitude at the end of the upwind/departure leg. But your Vgeac (haha very funny) does result in more airspeed at every point. My plane absolutely will not accelerate anywhere near cruise speeds while climbing in the pattern, unless I perform a Vgeac. This means I can both reach 1000' in the downwind and be generally faster. One thing seems clear, spending a lot of time in high drag flight does not result in more total energy in the pattern. As one might expect, getting over the nearby Class D requires effort. Keeping drag low seems to make it much easier. That means no flaps, gear up asap and accelerate first.
ha! you haven't lived until you have flown a 150hp C-177 (fixed gear) at gross weight (or maybe a little over...) from a grass strip in South Florida on a hot day...
You remind me of my time at Dunnottar, a very long time ago. I enjoy your videos. It would be great to have the benefit of your instructional skills, especially after my many decades of flying during which I've probably gained some bad habits. Living about a quarter of the way around the planet makes meeting you unlikely, if you're still in SA. Anyhow I'm a loyal subscriber.
Vx in an RV6 is about 1500 ft/min at 80 mph. Best glide at 90mph which means I'm at pattern altitude before the end of the runway with slight pitch over to bring speed up to best glide. If I have an engine failure, I will need to do "S" turns to prevent runway overshoot after return to runway alignment . But very few GA aircraft have this amount of performance. In a C150, you're screwed, blued, and tattooed on a hot day.
VCC is always best.. When I flew F-16s we flew VCC as I can zoom to do what I need. At the airlines, when I test fly airliners, VCC will always give me the energy to do what I need but I am in a twin. VX is always bad as when my engine quits, I have to give a big push to survive the engine failure. VY is a pinch better…I still have to push. VCC gives you more options. BIG picture. Despite what you use, you have to know what your choices are.. VX, big push to survive …VCC, you have a choice…. GREAT video…
Airline performance is ALL about scheduled performance. That means you schedule an engine failure at V1 on all takeoffs. Single engine operations are totally different.
It is true that drag is less flying in ground effect than flying above ground effect. But, is drag less flying in ground effect than accelerating on the runway with the weight supported by the wheels instead of the wings? On a rough field, yes. But, on a hard surface runway, I suspect that staying on the ground would actually be better.
In theory, maybe. But in reality, probably not. As soon as you reach flying speed, it will start flying, unless you keep pushing the nose down. I cringe at the thought, but let's say you do that. As speed builds up the wing will want to fly more and more, and you'll have to push the nose down harder and harder, which will increass tyre friction, and in the end the total friction (air + ground) will likely be more than it is in ground effect (air only). This is not to mention the good probability of pushing the propeller into the ground, and also the size wheels could exceed their rated speed, depending on type, especially if they have a small diameter. Light airplane wheels typically have quite low max speeds, but it varies quite a lot.
@@LetsGoAviate Ok, I agree with all you say there - especially the caution re prop strike and over speeding the mains - but with one caveat. Rolling resistance will not actually increase in this scenario because it is μ(W - L), where the experimentally determined coefficient, μ (0.03 typical for asphalt), is not a function of velocity. It is, in effect, 3% of weight on wheels (more for soft field of course). The friction itself (including hub bearing) may increase but is small enough to be considered negligible. I am a staunch advocate of sticking to POH recommendations, except as part of formalised flight test procedures. Nonetheless, the question boils down to how the above mentioned parameter compares to induced drag. The short answer to which is: at or close to recommended Vr the induced drag is reducing fast enough that you may as well just rotate and avoid the penalty of an increased ground run.
For small single prop, except short and soft, Vy would be the safest and as long as you don't go less than DMMS, which is always pretty much equal to Vy
Note for ground effect takeoffs:- there will be no data for this take off in your aircraft manuals, if you need obstacle clearance I would recommend sticking to published technique and speeds unless you are very experienced. If you exceed Vfe you are very unlikely to cause structural damage to the wing - you are more likely to damage the flaps or flap linkages. When executing a ground effect assisted takeoff, if your aircraft can takeoff flapless then I would recommend this technique over retracting flaps whilst flying in ground effect.
A soft field takeoff is basically a special case of a ground effect assisted takeoff once the plane is airborne. I guess one of those maneuvres most pilots don't ever need after passing their practical exam.
The soft field takeoff is actually the best short field takeoff. As Wolfgang says in "Stick and Rudder," try to hit the tree and then zoom over. My default takeoff is level in low ground effect until Vcc or end of runway or need to pitch just over an obstruction. No, not a special case.
There is no single indicated speed that works for all climbing situations. It's just not that simple, so here's a quick primer. Flying essentially begins with rotation at Vr and initial acceleration to the best angle of climb speed or Vx, which is also usually very near or equal to the best L/D ratio speed, where L is total lift and D is total drag. But Vx is normally quickly passed on most climbouts for pilots operating propellor-driven airplanes, which usually settle in at Vy, ie best rate of climb speed until out of the traffic pattern. Terrain ahedmigh forcea longerclimb a Vx, which might cause the engine's operating temperature to rise. Once out of the traffic pattern (or "the circuit" as it is called in Canada) with the landing gear and flaps retracted, many pilots will re-trim the nose dowward to about 5 degrees up, to accelerate to a cruise-climb speed with a value somewhat above Vy but well below Vmowhich provides better forward visibility. Many light aircraft climb fairly well throughout a range of indicated airspeeds. As the aircraft climbs higher and higher, all of its indicated speeds will become somewhat lower than their values at sea level. Vx and Vy are sometimes farly close to each other, particularly in smaller, lower-powered two-seater airplanes. But in more powerful designs they may be a greater gap between the two. A good example of the latter is the Grumman American AA-5B Tiger, with a Vx of about 81 mph (71 knots) and a significantly higher Vy of 104 mph (90.5 knots). One day back in the late 1970s I remember climbing a relatively lightly-loaded Grumman American Tiger with just myself and a brother aboard, from sea level up to 11,000 feet to tur Mount Baker, a dormant volcano in northwestern Washington. According to the AA-5b's pilot operating handbook, (POH) the indicated Vy value drops from 104 mph at sea level to about 81 mph at 11,000 feet. At that point, Vx and Vy were identical. That is because the air gets less and less dense as altitude increases, causing errors to accrue in the airspeed indicator, which pilots must understand and be aware of. That high up with a non-turbo-charged engine, climbing faster than 81 mph at 11,000 feet, would significantly reduce the available climb rate. Climbing at a lower indicated speed would also reduce climb rate. If the inattentive pilot keeps on decelerating that will ultimately leads to an aerodynamic stall. That is when the wing can no longer overcome the weight of the aircraft ie climb. This forces the nose down which restores relaielr smooth airflow over the topand bottom surfaces ofthe wing, allowing theairplane to accelerate back to a "climbable" indicated airspeed.
In a jet, Vx is achieved at best L/D angle of attack. However, in a propeller aircraft, Vx is achieved at a speed considerably less than best L/D AoA. In a prop plane, Vy is actually close to best L/D AoA. Also the reason Vx and Vy converge at the aircraft's ceiling has nothing to do with airspeed indicator error. It's because there's only one speed that will maintain level flight with the engine power/thrust available.
One unfortunate aspect of these POHs is that they give a single speed for Vx or Vy etc irrespective of weight. These speeds are provided for maximum takeoff weight. In a c172 you can be quite a bit lighter if you are alone and half fuel. The ideal Vx and Vy speeds would be lower in that case.
The faster, always the better! I prefer to accelerate at the highest possible rate with flaps fully retracted and elevator at zero lift for minimum possible drag and only lower the flap just for the highest lift/drag ratio (yes, at some very low flap setting, the lift/drag actually is higher than with flaps 0) when I'm a few seconds from the liftoff speed, speed which I calculate as needed in order to have the AoA at no higher than 5 degrees (most pilots don't understand what the AoA does by the way) and after the liftoff I keep flying as close to the ground as possible while raising the gear in order to build up as much speed as possible and as I build speed, I also raise the flaps back to zero and continue on building speed in ground effect until I get at over 70% VNE and from there I start climbing until I settle on the needed slope to hold a needed speed for the maximum lift/drag ratio AoA and keep it that way for as much as I need to climb. I do all of that to maximize the total energy at any given point on my flying pattern so that in case I remain with zero thrust, I can transfer that energy as I need. Most go for trying to increase their potential energy (height) very quickly, thinking that it's mostly height that is useful and they are partially wrong, because when they get surprised by a total loss of thrust, their psychological effects and fear/panic kick in, they lose the little speed they have rapidly, and even though they had maybe enough altitude built up to make a 200 deg turn, they'll mishandle the AoA and stall a wing and it's done for them. I only wish that airline pilots regulations would also allow them to build up as much speed as their runway length allows them to get before getting airborne for just that cause. The higher the speed, the more options of survival.
The V-speeds depend on weight too, especially Vx. If you're heavy it'll be faster. To make it obvious, consider what would happen as the plane becomes so light that it can fly almost straight up - you get an extremely steep climb at a very slow speed.
Yours is the most extensive and excellent coverage of energy management on takeoff and Wolfgang's law of the roller coaster I have seen. Eleven of my thirteen engine failures have been at 200' AGL or lower crop dusting and patrolling pipelines. While the physics of the kinetic vs. potential energy seems equal, save the extra free kinetic energy provided by ground effect, I have found airspeed and not altitude to be life down here where I worked so many years. As a crop duster (load) and mountain (high DA) pilot for so many years, the basic level in low ground effect (extra free kinetic energy) takeoff and down drainage egress (free potential energy) were default. Most pilots don't need the extra free kinetic energy until they need it (too late), but videos and statistics corroborate my empirical data. We very much need, in my opinion, to emphasize altitude (the Vy argument) less and airspeed (the ground effect and Vcc argument) more. The fatal aspect of poorly done takeoff and/or go around seems to be achieving enough altitude quickly to kill in the stall/fall. Vx or Vy as appropriate, never appropriate on long runways, and pitch to achieve a positive rate of climb, often initiated at way too slow airspeed, seem to orientate students and even experienced pilots toward altitude rather than airspeed. How do we change this equation?
I think many pilots are caught-out by how fast airspeed dissipates at engine failure. I also don't believe the average pilot can save it at low level with an engine failure during a Vx climb, the bigger problem being that not all pilots realise this danger. A pilot has to be able to accept the losses when trading altitude for airspeed, and this goes against the natural instinct of wanting to pull up as the ground comes closer, so you may very well be right that airspeed (kinetic) might be the safer energy of the two.
You make some very interesting points. Vx climbs are definitely the deadlier ones, but not paying attention and the startle factor could easily push a pilot beyond the recovery envelope in other climbs too. Some aircraft may have a high enough inertia to give you a smidge more time to react but it won't be much money in the bank. While flying a 600kg class microlight and a similar weight Eurofox my instructor put me through Vx climb engine failure scenarios. Due to their very low inertia the airspeed decays almost instantly to stall speed & beyond. The only thing in your response armoury is the muscle memory to shove that nose down as fast as possible, gained by regular practice. Can you please explain "down drainage egress". It's not a term I understand.
@@theflyingfool Except for marshland, and especially in folding fault and volcanic formed mountains, rain water and snow melt drains in valleys between ridges all the way to an ocean. Rather than GPS direct, using drainage systems (valleys) is the safer way to ingress and egress the mountains or actually any terrain other than ocean, lake, or marshland. Part of takeoff from high altitude airports, especially mid day with higher DA, is to use topographical maps or at least the sectional to determine down drainage egress. I have flown and instructed in most light 65-150 hp training airplanes from airports above 7,000' MSL. Level in low ground effect to Vcc and down drainage egress have often equaled 50% of total energy available. Crop dusting with the 235 hp Pawnee and 100 gallons in the hopper often meant down drainage was the only way I could go. Vy in the mountains often is required just to maintain altitude in the rivers of air in which we fly. Here are both orographic lift possibilities and thermal lift possibilities, so POH ceiling means little. Those pilots who are unfamiliar with these conditions may find up drainage egress out of places like Angel Fire, NM or Telluride, Colorado not to work. But then it is too late. That is why the basic level in low ground effect to Vcc, and with no wind consideration down drainage egress, everywhere actually, is default for me. We don't need the extra energy until we need it, but I am not very organized.
13 engine failures!? You need a new engineer mate! 😂 (Unless you have about 50,000 hours piston time and then that would be about right!) Wise words. There is no one size fits all solution. Based on terrain, aircraft performance and numerous other factors there will be a safest departure profile. That’s where experience comes in. Solution to the training problem? Give pilot more training - simple! Get more pilots gliding - where every flight is an engine failure after takeoff. Winch launch is an extreme Vx, aerotow is ground effect assisted.
On commercial flight, there is a concept of "improved climb" that uses excessive runway to accelerate to higher speed ,technically, more closer to Vx, rather than exceed it. but the "ground effect" stuff seems quite similar to that, so my questing is rather than using ground effect. why not just accelerate on the runway, which you can stay at near 0 lift AOA thus very little drag.
If you experience the basic level in low ground effect takeoff, you will see how much that friction drag of the wheels rolling on the surface delays airspeed development by comparison. The design of the airplane is to fly, not to roll on the ground. Start with the yoke all the way back. When the nose wheel (if tail wheel, you will have to push the yoke to level the fuselage as soon as possible) comes just off, use dynamic elevator to fix it just there. This should happen quickly or abort. When the wing will carry the weight of the airplane in low ground effect (this is much slower than Vx, Vy, or even Vso, an out of ground effect number), use aft elevator to bring the mains off. Now we are off the surface but at too high pitch attitude. Work the elevator fore/aft rapidly to bracket level in low ground effect. In low powered airplanes the trick is to no touch back down while leveling. In high powered airplanes the trick is to push (if trim set for Vy climb) the nose down hard to get level in low ground effect. Now acceleration is very rapid to Vcc in far less runway than even required to accelerate to Vy on the surface. In strong crosswinds, I position the airplane on the downwind corner of the runway pointed at the upwind thousand feet mark. In this new thousand feet centerline I can easily, with all that extra now headwind component and ground effect, get off and accelerated to near Vcc in a C-172 size/power airplane. Now, for comfort, I rudder turn in low ground effect to go on down the upwind side of the runway or just climb at this angle if no obstructions or traffic. This is a technique every crop duster, sorry Ag now, uses. Also every takeoff with full load at high DA airports should use this technique and down drainage egress. We don't need this extra free ground effect acceleration energy until we need it. If already at a couple hundred feet when we realize we needed it, it is too late. Why is climbing at a very uncomfortable pitch attitude to get high enough for stall, with or without spin, to be fatal the school solution for airplanes without moon rocket quality propelsion?
My friend died in a Supercub month or so ago. Being more powerful he could have done a steep climb Vx and lost power, we are not sure what really happened.. Gained apparently 100 feet height in a short distance. Nose dive to ground and burst into flame. Look up G-CUBX crash.
Doing a zoom pullup over a friends house is a frequent killer. Testing this with my Citabria, I was amazed at how quickly the speed washed off. Being ready, I pushed hard forward to catch it before the stall and realized why so many had died this way.
I feel like you still haven't answered which speed results in the most total energy. Vy climb results in the most potential energy, but I'd rather be at 1000 feet at 100 knots than at 1050 feet at 70 knots. I feel like the answer is somewhere between Vy and Vcc?
It can be calculated but gets more complicated as drag also enters the equasion. I'd say it would usually be close. Between Vy and Vcc you are just changing the composition of the equasion without changing the result (by much).
Should not you pitch for best glide speed anyway in an event of engine failure? So especially with Vcc, instead of wasting energy to high drag (due to high airspeed) i think you should immediately convert speed for altitude, resulting higher altitude, and optimal glide speed? Of course the maneuvering itself could lead into energy losses, so i am not certain at all which is safer in the real world
You should pitch for best glide yes. These comparisons are all based on getting to best glide after engine failure. I'm not saying to glide at Vx, Vy or Vcc. At Vcc suffering an engine failure you'll be at best glide without much input in a few seconds, probably before the pilot can react, depending on the plane and how fast Vcc was of course. At a safe altitude, doing some engine failure simulation in a climb one can see how fast airspeed drops in the first 3 second. At Vy you'll have to actively (not shoving it though) push the nose down to not go below best glide. I can't speak for all aircraft types though.
Good points. For 17,000 hours I lived with less than 200' of altitude. Airspeed is life down here. Airspeed, zoom reserve airspeed, enough airspeed to maneuver without doubt, saved me eleven times when the engine failed there. Yes, altitude is safety. It is also time. Some of my low altitude forced landings would not have been necessary with more time to evaluate. Mine were all six second deals. I went to survivable landing zones in the very near hemisphere in front of the wing. It usually took full flaps and one rudder pedal to the stop forward slip to get into the beginning of those LZs. High altitude orientation (altitude is best, checklist, settle down and work it out, best glide airspeed) will kill you down here.
Best rate of climb (Vy) will produce the fastest climb. "Best rate" means higest fpm possible. Climbing at the highest angle possible (Vx, best angle of climb) will result in less rate of climb.
@@LetsGoAviate I understand and my comment stands. If you have a short runway and need to clear 70’ trees at the end, Vx is much safer than a faster Vy. Different scenarios dictate which V speed is safest and it isn’t always the speed that is faster or has the lowest deck angle.
@@LTVoyager I mean, that goes without saying. You need to clear the trees amd don't have the option of doing anything other than Vx. And I thought I covered that when I said that Vx is used for obstacle clearance and why Vx works best for that. Doesn't change the point of the video though.
At 4:33 My VSI indicates considerably HIGHER FPM climb rate at Vx than Vy. Not lower climb than Vy as the author claims. In addition, an early Vx climb gives me more runway remaining and maybe other landing options for an early engine out...
Vx with a higher vertical speed than Vy is an Oxymoron. Vy is the best rate of climb, you can't climb faster than your fastest rate of climb. Whatever airspeed gives you the highest fpm gain, thats your Vy.
Look at the videos. Why do pilots wish to quickly get high enough for an inadvertent stall, which they are much nearer at slower airspeed, to be fatal? Too many stall/fall into the middle of a long runway. What kind of total energy management is that?
A blast shield on an aircraft carrier does not increase jet performance, as jet engines propulsion is based on momentum. It's just there to protect other aircraft.
I like your explanation of the various climb speeds and their consequence for obstacle and terrain clearance.
Thanks. You are correct, I don't think jet performance plays any factor in the use of a jet blast door. And when using a catapult, it wouldn't even make sense to use it to increase thrust (as the catapult does the work). Thanks for the correction.
But it will increase thrust nonetheless. The blast door redirects air up at a fairly high angle, and in turn resists the free flow of air backwards horizontally (the direction it is spewed out of the engine). That resistance of free flow increases pressure at the point the air gets redirected. The point of the jet blast door is to shield what's behind it. Without it, if a person was behind the jet as it powers up, they would likely be blown off deck, correct? That's because of the force enacted on the person. If you push against a wall, the wall pushes back just as hard. So both in terms of fluid dynamics and newton's 3rd law, thrust will be increased. I don't know how much additional thrust is provided though.
@@LetsGoAviate Actually, that increase in exhaust nozzle pressure force is adversely compensated for by a decrease in exhaust gas momentum (because exhaust gas velocity decreases when exhausting to a higher pressure). At best you'd break even, but a small decrease in overall thrust is actually more likely as the nozzle exit plane pressure and momentum tend to not trade exactly one for one and momentum is the bigger driver. You can do a CFD simulation and prove it to yourself by integrating pressure, friction, and momentum forces over your control volume.
@@LetsGoAviate no
And helicopters can hover at the same altitude or maximum weight whether in ground effect or not. Oh, wait…
What is astonishing is how many pilots disregard the POH despite the fact that the designers have studied all the possible scenarios and the manual is a compilation of their knowledge and experience. Bad habits and incorrect reflexes, especially if acquired from poor instruction, can eventually lead to disaster. If the engine fails at an early stage of climb out, the natural reaction to keep the nose up is fatal. My CFI would never let anyone solo until they had the acquired the reflex to lower the nose and preserve the airspeed.
You have a good CFI. If that engine starts sputtering, or even dies immediately, studies have shown that many pilots take about 3-4 seconds to realize what has just happened. Good CFIs train their "students" to get the nose done immediately, even if it creates negative Gs while doing so.
Early/previous training in gliders is also very helpful as students are trained at an early stage to respond instinctively to a cable break by pitching down for airspeed.
My old plane won't make book numbers, and I'm not alone in this. (Comes closer with the Powerflow exhaust, GAMI injectors and K+N airfilter). The reason: It's overweight. I have scales in my shop. For planning purposes, I weighed it with interior and all insulation removed, no oil, no fuel, no avionics, it was still 100 pounds above Cessna's claimed numbers!
@@cujet That is very interesting. Do you have the same wheel skirts as the original? Have they been removed? Wheel skirts reduce drag, as you know. Have you added any new parasite drag components?
It's possible either your scales or Cessna's scales weren't calibrated against a standard weight. But still, one wouldn't think that 100 lbs. would not make much of a difference in the book numbers.
My buddy's Mooney M20C consistently trues out between 145-147 kts at higher altitudes whether it's at gross weight or much lighter.
@@cujet Do you mea they lied about the empty weight ?
I got my PPL in Texas in a C152II Aerobat. Two grown men in a tiny 152 in 90+ degree heat and 1200'+ field elevation? Yeah, we used ground effect a lot.
😁 I bet you did.
Wild to think about that :)
A great video to show students. All take off speeds explained.
In ground effect wing tip vortices are less too, so less drag and more acceleration. You get to Vy sooner and can start climbing.
@@Iwishiwasanoscarmeyerweiner She said all that?
Really well explained and illustrated. Thanks for this.
Great job explaining a very important aspect of takeoff, which lately seems to be something that many either don't know or don't understand.
Thank you Jaco...a lot for pilots to think about and this shows the importance of planning ahead and know your aircraft
Ground effect acceleration is very helpful for an unpaved runway. Wet grass, mud, etc is minimized and safe climb speed achieved just after lifting off.
It is my default on every takeoff until Vcc or when an obstruction requires pitch up to just clear. Airspeed, and not altitude, is life until high enough to recover from inadvertent stall.
This. Get the wheels off the grass for max acceleration without the drag from the wheels. It gets you to a safe climb speed with less runway behind you.
Isn’t this literally the definition of a soft field landing? Lift the nose and get off the ground as soon as possible, push forward and use ground effect to accelerate to Vx or even Vy then climb.
Of course, one might want to remove flaps to get to a higher Vy but removing float close to the ground is not worth the risk.
@@lordcraycray2921 Vy is the math most up for time, but that doesn't make it safer than using runway still ahead, level in low ground effect, until fast enough to maneuver safely regardless of what happens next. Vx or Vy are not safe airspeeds when too low to recover from an inadvertent stall which is usually fatal.
After a scary uphill takeoff at the Spring Hill 70N airport in Pennsylvania, I have three suggestions: 1) Never fly to an airport named "Hill", 2) Remember that sometimes you should (must!) takeoff downwind instead of straight towards a steep hill, 3) Memorize your plane's Vx speed because you might need it to climb a hill.
For this one the rule to live by is downhill beats downwind.
Great video. I used to live at at KAXX (Angel Fire, NM) where field elevation is 8,380 feet and DA is typically >10,000’. The runway was long (8,900 feet) and I would advocate for ground effect assisted takeoff all the time. With the long runway, staying in ground effect after the wheels leave the ground somewhere around 2,000 feet for most NA GA planes, gave pilots the ability to just pull back power and land easily if there was a need to abort.
My personal way of doing this in my Turbo Saratoga was to start with a static takeoff, trim down slightly, one notch of flaps. Stop at the end of the runway, spin up the engine to 36” of manifold pressure, check all gauges, release the brakes. Lift off at 76 knots and accelerate in ground effect until I reach the edge of the white arc (max flap speed), and then I pop in the 2nd notch of flaps, which is 20 degrees for me, which also happens to be my “maximum lift flap settings” (which would be a good video to do). With the slight nose down trim, just putting in the 20 degrees of flaps leads to a 1000 rpm climb rate, at a good airspeed, and I do not even have to change my yoke pressure to do it. Once I get to 1500 feet AGL, I can pull the turbocharger out of the engine, drop the flaps, and have sufficient altitude to be able to make a safe landing if I needed to.
Glad you did this video, you stated the obvious very nicely (nicer than me according to my wife) when you said a “ground effect assisted takeoff takes a focused and competent pilot”. My wife flies with me all the time, works my checklists with me, and works the radio. We always observe sterile cockpit until we reach 3000 feet AGL.
If you are interested, I did a safety video about the nuances of flying in and out of Angel Fire, and I briefly mention the ground effect assisted takeoff. You can find that video here. ruclips.net/video/AmrAX7tSvvQ/видео.htmlsi=ef97HOAyuZekBf5e
In a Cessna 182, a cruise climb is done using 90% power setting. Full power suggested use is up to 30 seconds for cooling reasons. A low wing plane flying in ground effect works rather well. In my Cessna 150, I hold close to the runway until aproaching VY because of the low available power. So, not only the terrain situation matters but the type of aircraft too.
Great video! Standard pilot training is to use VX to clear of obstacles and then VY for climb out. Advantage of VX is that if there is an issue with climb you find out early and may still have available runway to land on. In the event of engine failure you need to get to best glide as fast as you can. For example, in Cessna 172 VX is 56, Best glide is 65 and VY is 76 so +10 knots for VX or -10 knots for VY. On cold days my favorite is Ground assisted acceleration and then a pull up as it feels like you are in a way better plane than you actually are. I wouldn’t use cruise climb for anything other than cruise climb. Good way to keep the engine cool on those long climbs to altitude if ATC permits.
Just put a Blue Line on full gross Vglide speed. Vx is a few knots under, Vy a few knots over depending on weight. We had them on all the 1990's airplanes we flew at our flight school. We had the best students flying in crosswinds when the 2 other flight schools could not fly. Laggards they were..
This video is the first time that I have heard the term “Vcc.” Even an article on Pilot Institute dated October 9,2023 doesn’t use this term. Interesting video. Thanks!
Excellent video. In the UK in the 80s a microlight aircraft was developed that used ground effect as its standard take off procedure. The Chevron was underpowered, to keep within weight regulations, and so was developed to utilise this phenomenon
Ve
ry well explained. Exactly what I gleaned from my CFIs, FAA pubs, and experience.
When to 3-point and when to Wheel land your Taildragger : ruclips.net/video/45cQxfK-3MM/видео.html
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4 Biggest Propeller Myths Explored : ruclips.net/video/Vgj3Bbwqtjs/видео.html
Velocity speeds are important for sure. Rates and angles are to be factored in when considering all elements involved.
Great explanation & food for thought, especially as regards time required to convert potential energy to kinetic energy...
When climbing at Vx the windshields angle of incident is shallowest thus reducing the forces in the event of a bird strike. During times of high bird activity at my home airport I often choose a Vx climb to get up quickly and also lessen the chance of eating bird mixed with shards of acrylic. It’s difficult to transition to best glide speed when half of your face is missing.
Intersting. We learned to climb with vy in order to minimize time in the altitude below 2000ft (where most birds are).
this is brilliantly explained! thank you!
Just one addition. If you have a BRS, it's always Vy until that BRS becomes available, of course after clearing obstacles. I usually have ample runway left accelerating to Vy in ground effect and clearing obstacles without having to climb with Vx. The "CAPS available" callout feels good 😊
Yet another excellent presentation. Thank you
"Best" answer: it depends. Love it and, I agree.
Looking into POHs, Vcc is seldom given. There are some with graphs that show the change in Vy and Vx speeds with altitude. I guess you could halve the difference in cruise speed and Vy and use that?
For the crop duster it is not a number in the POH. Energy is life and ground effect is free energy. Roll on the wheels, less energy. Pitch up while slow and lots of ground effect left, less energy. Level in low ground effect so long as runway ahead, more energy. Down drainage egress is potential energy of altitude you didn't have to give up any airspeed for, more energy. Again free energy. In small trainers and crop dusters, ground effect, down drainage, thermal lift, and orographic lift often equaled 50% of total energy available. In really rough air or mountain wave, natural energy far exceeds fuel energy. And it is free.
I had power fail in a Tomahawk turning crosswind at 600 feet. I grabbed controls from the student, stuffed nose down to 80 kts, turned and landed on cross alternate runway. Always glide higher than best glide, you have something to play with.
And a windmilling failed engine produces more drag than a idling lower power practise.
I would think if you are climbing out at Vcc and have an engine failure, you should in fact climb a little to gain altitude until you slow to Vglide so that you now have the highest possible altitude and are configured at the best glide speed for maximum distance possible.
That's true, because that way less energy is lost to drag. However it's safer to have reflexes to pitch down than up. If you have the brain space to think in that instance, then pitch up for best glide after the reflex.
Yeah. I was thinking that exact point. “Am I really going to be able to think all that through in the moment?”I hope I’d actually immediately pitch down, but then adjust after. I think I’ll take a little loss in energy as long as pitching down is a reflex!
@@arpeltier My engine failures were six second deals. I always had airspeed from ground effect on takeoff or in the spray swath in the field. This allowed me to maneuver as necessary to what looked best in the very near hemisphere from a couple hundred feet at most. No pitch down is necessary with zoom reserve airspeed. An energy management 1 g turn at any bank angle is available. Pitch up wings level, turn to a good site while releasing all back pressure on the stick, this allows the nose to go down as designed to prevent stall, add full flaps and forward slip (I was almost always high and fast to what I could see from down low), and touchdown slowly and softly in the beginning of the landing zone. Flying all the way to the crash works best. What to do is pretty obvious so not a lot to think through in seconds...no moment available.
Great video, thanks! I own and fly a Mighty Thunder Cardinal 177RG (a little joke, as there is no thunder and no might). Accelerating in true ground effect is really too low for my comfort level, but I've tried Vx, Vy and Vzoom, albeit above ground effect, and noted my altitude and speed in the pattern at different points. Flying out of F45, I like to get over 2500', to avoid the adjacent Class D. All methods will result in about 500 feet of altitude at the end of the upwind/departure leg. But your Vgeac (haha very funny) does result in more airspeed at every point. My plane absolutely will not accelerate anywhere near cruise speeds while climbing in the pattern, unless I perform a Vgeac. This means I can both reach 1000' in the downwind and be generally faster. One thing seems clear, spending a lot of time in high drag flight does not result in more total energy in the pattern. As one might expect, getting over the nearby Class D requires effort. Keeping drag low seems to make it much easier. That means no flaps, gear up asap and accelerate first.
ha! you haven't lived until you have flown a 150hp C-177 (fixed gear) at gross weight (or maybe a little over...) from a grass strip in South Florida on a hot day...
You remind me of my time at Dunnottar, a very long time ago. I enjoy your videos. It would be great to have the benefit of your instructional skills, especially after my many decades of flying during which I've probably gained some bad habits. Living about a quarter of the way around the planet makes meeting you unlikely, if you're still in SA. Anyhow I'm a loyal subscriber.
Yeah I'm still in SA. Thank you for the ongoing support!
Vx in an RV6 is about 1500 ft/min at 80 mph. Best glide at 90mph which means I'm at pattern altitude before the end of the runway with slight pitch over to bring speed up to best glide. If I have an engine failure, I will need to do "S" turns to prevent runway overshoot after return to runway alignment . But very few GA aircraft have this amount of performance. In a C150, you're screwed, blued, and tattooed on a hot day.
VCC is always best.. When I flew F-16s we flew VCC as I can zoom to do what I need. At the airlines, when I test fly airliners, VCC will always give me the energy to do what I need but I am in a twin. VX is always bad as when my engine quits, I have to give a big push to survive the engine failure. VY is a pinch better…I still have to push. VCC gives you more options. BIG picture. Despite what you use, you have to know what your choices are.. VX, big push to survive …VCC, you have a choice…. GREAT video…
Thanks for the comment, nice to hear from a military/airline/test pilot on the subject!
Airline performance is ALL about scheduled performance. That means you schedule an engine failure at V1 on all takeoffs. Single engine operations are totally different.
It is true that drag is less flying in ground effect than flying above ground effect. But, is drag less flying in ground effect than accelerating on the runway with the weight supported by the wheels instead of the wings? On a rough field, yes. But, on a hard surface runway, I suspect that staying on the ground would actually be better.
In theory, maybe. But in reality, probably not. As soon as you reach flying speed, it will start flying, unless you keep pushing the nose down. I cringe at the thought, but let's say you do that. As speed builds up the wing will want to fly more and more, and you'll have to push the nose down harder and harder, which will increass tyre friction, and in the end the total friction (air + ground) will likely be more than it is in ground effect (air only).
This is not to mention the good probability of pushing the propeller into the ground, and also the size wheels could exceed their rated speed, depending on type, especially if they have a small diameter. Light airplane wheels typically have quite low max speeds, but it varies quite a lot.
@@LetsGoAviate Ok, I agree with all you say there - especially the caution re prop strike and over speeding the mains - but with one caveat. Rolling resistance will not actually increase in this scenario because it is μ(W - L), where the experimentally determined coefficient, μ (0.03 typical for asphalt), is not a function of velocity. It is, in effect, 3% of weight on wheels (more for soft field of course). The friction itself (including hub bearing) may increase but is small enough to be considered negligible.
I am a staunch advocate of sticking to POH recommendations, except as part of formalised flight test procedures. Nonetheless, the question boils down to how the above mentioned parameter compares to induced drag. The short answer to which is: at or close to recommended Vr the induced drag is reducing fast enough that you may as well just rotate and avoid the penalty of an increased ground run.
For small single prop, except short and soft, Vy would be the safest and as long as you don't go less than DMMS, which is always pretty much equal to Vy
Note for ground effect takeoffs:- there will be no data for this take off in your aircraft manuals, if you need obstacle clearance I would recommend sticking to published technique and speeds unless you are very experienced.
If you exceed Vfe you are very unlikely to cause structural damage to the wing - you are more likely to damage the flaps or flap linkages.
When executing a ground effect assisted takeoff, if your aircraft can takeoff flapless then I would recommend this technique over retracting flaps whilst flying in ground effect.
A soft field takeoff is basically a special case of a ground effect assisted takeoff once the plane is airborne. I guess one of those maneuvres most pilots don't ever need after passing their practical exam.
The soft field takeoff is actually the best short field takeoff. As Wolfgang says in "Stick and Rudder," try to hit the tree and then zoom over. My default takeoff is level in low ground effect until Vcc or end of runway or need to pitch just over an obstruction. No, not a special case.
I think one thing missing here is that at higher speeds there is also higer drag. So the total energy at vcc is lower after some time than at vy
There is no single indicated speed that works for all climbing situations. It's just not that simple, so here's a quick primer.
Flying essentially begins with rotation at Vr and initial acceleration to the best angle of climb speed or Vx, which is also usually very near or equal to the best L/D ratio speed, where L is total lift and D is total drag. But Vx is normally quickly passed on most climbouts for pilots operating propellor-driven airplanes, which usually settle in at Vy, ie best rate of climb speed until out of the traffic pattern. Terrain ahedmigh forcea longerclimb a Vx, which might cause the engine's operating temperature to rise. Once out of the traffic pattern (or "the circuit" as it is called in Canada) with the landing gear and flaps retracted, many pilots will re-trim the nose dowward to about 5 degrees up, to accelerate to a cruise-climb speed with a value somewhat above Vy but well below Vmowhich provides better forward visibility.
Many light aircraft climb fairly well throughout a range of indicated airspeeds. As the aircraft climbs higher and higher, all of its indicated speeds will become somewhat lower than their values at sea level.
Vx and Vy are sometimes farly close to each other, particularly in smaller, lower-powered two-seater airplanes. But in more powerful designs they may be a greater gap between the two. A good example of the latter is the Grumman American AA-5B Tiger, with a Vx of about 81 mph (71 knots) and a significantly higher Vy of 104 mph (90.5 knots).
One day back in the late 1970s I remember climbing a relatively lightly-loaded Grumman American Tiger with just myself and a brother aboard, from sea level up to 11,000 feet to tur Mount Baker, a dormant volcano in northwestern Washington. According to the AA-5b's pilot operating handbook, (POH) the indicated Vy value drops from 104 mph at sea level to about 81 mph at 11,000 feet. At that point, Vx and Vy were identical. That is because the air gets less and less dense as altitude increases, causing errors to accrue in the airspeed indicator, which pilots must understand and be aware of.
That high up with a non-turbo-charged engine, climbing faster than 81 mph at 11,000 feet, would significantly reduce the available climb rate. Climbing at a lower indicated speed would also reduce climb rate.
If the inattentive pilot keeps on decelerating that will ultimately leads to an aerodynamic stall. That is when the wing can no longer overcome the weight of the aircraft ie climb. This forces the nose down which restores relaielr smooth airflow over the topand bottom surfaces ofthe wing, allowing theairplane to accelerate back to a "climbable" indicated airspeed.
In a jet, Vx is achieved at best L/D angle of attack. However, in a propeller aircraft, Vx is achieved at a speed considerably less than best L/D AoA. In a prop plane, Vy is actually close to best L/D AoA. Also the reason Vx and Vy converge at the aircraft's ceiling has nothing to do with airspeed indicator error. It's because there's only one speed that will maintain level flight with the engine power/thrust available.
Sounds like the safest approach to me is to maintain your engine so well that there's never an engine failure at that critical moment to begin with.
One unfortunate aspect of these POHs is that they give a single speed for Vx or Vy etc irrespective of weight. These speeds are provided for maximum takeoff weight. In a c172 you can be quite a bit lighter if you are alone and half fuel. The ideal Vx and Vy speeds would be lower in that case.
The faster, always the better! I prefer to accelerate at the highest possible rate with flaps fully retracted and elevator at zero lift for minimum possible drag and only lower the flap just for the highest lift/drag ratio (yes, at some very low flap setting, the lift/drag actually is higher than with flaps 0) when I'm a few seconds from the liftoff speed, speed which I calculate as needed in order to have the AoA at no higher than 5 degrees (most pilots don't understand what the AoA does by the way) and after the liftoff I keep flying as close to the ground as possible while raising the gear in order to build up as much speed as possible and as I build speed, I also raise the flaps back to zero and continue on building speed in ground effect until I get at over 70% VNE and from there I start climbing until I settle on the needed slope to hold a needed speed for the maximum lift/drag ratio AoA and keep it that way for as much as I need to climb. I do all of that to maximize the total energy at any given point on my flying pattern so that in case I remain with zero thrust, I can transfer that energy as I need. Most go for trying to increase their potential energy (height) very quickly, thinking that it's mostly height that is useful and they are partially wrong, because when they get surprised by a total loss of thrust, their psychological effects and fear/panic kick in, they lose the little speed they have rapidly, and even though they had maybe enough altitude built up to make a 200 deg turn, they'll mishandle the AoA and stall a wing and it's done for them. I only wish that airline pilots regulations would also allow them to build up as much speed as their runway length allows them to get before getting airborne for just that cause. The higher the speed, the more options of survival.
If Vx clears the trees at the end of the runway and Vy does not, I’d say that faster is most definitely not always better.
The V-speeds depend on weight too, especially Vx. If you're heavy it'll be faster. To make it obvious, consider what would happen as the plane becomes so light that it can fly almost straight up - you get an extremely steep climb at a very slow speed.
Yes. The V-speeds in the POH should be at MAUW. So if you are lighter, Vx and Vy will be a slower airspeed.
Yours is the most extensive and excellent coverage of energy management on takeoff and Wolfgang's law of the roller coaster I have seen. Eleven of my thirteen engine failures have been at 200' AGL or lower crop dusting and patrolling pipelines. While the physics of the kinetic vs. potential energy seems equal, save the extra free kinetic energy provided by ground effect, I have found airspeed and not altitude to be life down here where I worked so many years. As a crop duster (load) and mountain (high DA) pilot for so many years, the basic level in low ground effect (extra free kinetic energy) takeoff and down drainage egress (free potential energy) were default. Most pilots don't need the extra free kinetic energy until they need it (too late), but videos and statistics corroborate my empirical data. We very much need, in my opinion, to emphasize altitude (the Vy argument) less and airspeed (the ground effect and Vcc argument) more. The fatal aspect of poorly done takeoff and/or go around seems to be achieving enough altitude quickly to kill in the stall/fall. Vx or Vy as appropriate, never appropriate on long runways, and pitch to achieve a positive rate of climb, often initiated at way too slow airspeed, seem to orientate students and even experienced pilots toward altitude rather than airspeed. How do we change this equation?
I think many pilots are caught-out by how fast airspeed dissipates at engine failure. I also don't believe the average pilot can save it at low level with an engine failure during a Vx climb, the bigger problem being that not all pilots realise this danger.
A pilot has to be able to accept the losses when trading altitude for airspeed, and this goes against the natural instinct of wanting to pull up as the ground comes closer, so you may very well be right that airspeed (kinetic) might be the safer energy of the two.
You make some very interesting points. Vx climbs are definitely the deadlier ones, but not paying attention and the startle factor could easily push a pilot beyond the recovery envelope in other climbs too. Some aircraft may have a high enough inertia to give you a smidge more time to react but it won't be much money in the bank.
While flying a 600kg class microlight and a similar weight Eurofox my instructor put me through Vx climb engine failure scenarios. Due to their very low inertia the airspeed decays almost instantly to stall speed & beyond. The only thing in your response armoury is the muscle memory to shove that nose down as fast as possible, gained by regular practice.
Can you please explain "down drainage egress". It's not a term I understand.
@@theflyingfool Except for marshland, and especially in folding fault and volcanic formed mountains, rain water and snow melt drains in valleys between ridges all the way to an ocean. Rather than GPS direct, using drainage systems (valleys) is the safer way to ingress and egress the mountains or actually any terrain other than ocean, lake, or marshland. Part of takeoff from high altitude airports, especially mid day with higher DA, is to use topographical maps or at least the sectional to determine down drainage egress. I have flown and instructed in most light 65-150 hp training airplanes from airports above 7,000' MSL. Level in low ground effect to Vcc and down drainage egress have often equaled 50% of total energy available. Crop dusting with the 235 hp Pawnee and 100 gallons in the hopper often meant down drainage was the only way I could go. Vy in the mountains often is required just to maintain altitude in the rivers of air in which we fly. Here are both orographic lift possibilities and thermal lift possibilities, so POH ceiling means little. Those pilots who are unfamiliar with these conditions may find up drainage egress out of places like Angel Fire, NM or Telluride, Colorado not to work. But then it is too late. That is why the basic level in low ground effect to Vcc, and with no wind consideration down drainage egress, everywhere actually, is default for me. We don't need the extra energy until we need it, but I am not very organized.
By learning things from those who can teach them correctly/better. That's the first step.
13 engine failures!?
You need a new engineer mate! 😂
(Unless you have about 50,000 hours piston time and then that would be about right!)
Wise words.
There is no one size fits all solution. Based on terrain, aircraft performance and numerous other factors there will be a safest departure profile. That’s where experience comes in.
Solution to the training problem? Give pilot more training - simple!
Get more pilots gliding - where every flight is an engine failure after takeoff. Winch launch is an extreme Vx, aerotow is ground effect assisted.
On commercial flight, there is a concept of "improved climb" that uses excessive runway to accelerate to higher speed ,technically, more closer to Vx, rather than exceed it. but the "ground effect" stuff seems quite similar to that, so my questing is rather than using ground effect. why not just accelerate on the runway, which you can stay at near 0 lift AOA thus very little drag.
If you experience the basic level in low ground effect takeoff, you will see how much that friction drag of the wheels rolling on the surface delays airspeed development by comparison. The design of the airplane is to fly, not to roll on the ground. Start with the yoke all the way back. When the nose wheel (if tail wheel, you will have to push the yoke to level the fuselage as soon as possible) comes just off, use dynamic elevator to fix it just there. This should happen quickly or abort. When the wing will carry the weight of the airplane in low ground effect (this is much slower than Vx, Vy, or even Vso, an out of ground effect number), use aft elevator to bring the mains off. Now we are off the surface but at too high pitch attitude. Work the elevator fore/aft rapidly to bracket level in low ground effect. In low powered airplanes the trick is to no touch back down while leveling. In high powered airplanes the trick is to push (if trim set for Vy climb) the nose down hard to get level in low ground effect. Now acceleration is very rapid to Vcc in far less runway than even required to accelerate to Vy on the surface. In strong crosswinds, I position the airplane on the downwind corner of the runway pointed at the upwind thousand feet mark. In this new thousand feet centerline I can easily, with all that extra now headwind component and ground effect, get off and accelerated to near Vcc in a C-172 size/power airplane. Now, for comfort, I rudder turn in low ground effect to go on down the upwind side of the runway or just climb at this angle if no obstructions or traffic.
This is a technique every crop duster, sorry Ag now, uses. Also every takeoff with full load at high DA airports should use this technique and down drainage egress. We don't need this extra free ground effect acceleration energy until we need it. If already at a couple hundred feet when we realize we needed it, it is too late. Why is climbing at a very uncomfortable pitch attitude to get high enough for stall, with or without spin, to be fatal the school solution for airplanes without moon rocket quality propelsion?
What do you recommend for rare overload takeoffs (no obsticles, long runaway, sea level performance)?
With only that context, accelerate in ground effect and climb out at Vy
My friend died in a Supercub month or so ago. Being more powerful he could have done a steep climb Vx and lost power, we are not sure what really happened.. Gained apparently 100 feet height in a short distance. Nose dive to ground and burst into flame. Look up G-CUBX crash.
Doing a zoom pullup over a friends house is a frequent killer. Testing this with my Citabria, I was amazed at how quickly the speed washed off. Being ready, I pushed hard forward to catch it before the stall and realized why so many had died this way.
I feel like you still haven't answered which speed results in the most total energy. Vy climb results in the most potential energy, but I'd rather be at 1000 feet at 100 knots than at 1050 feet at 70 knots. I feel like the answer is somewhere between Vy and Vcc?
It can be calculated but gets more complicated as drag also enters the equasion. I'd say it would usually be close. Between Vy and Vcc you are just changing the composition of the equasion without changing the result (by much).
Maybe stay on the runway longer to get more speed before lifting off?
All these speeds are the safest for the correct situation.
Should not you pitch for best glide speed anyway in an event of engine failure? So especially with Vcc, instead of wasting energy to high drag (due to high airspeed) i think you should immediately convert speed for altitude, resulting higher altitude, and optimal glide speed? Of course the maneuvering itself could lead into energy losses, so i am not certain at all which is safer in the real world
You should pitch for best glide yes. These comparisons are all based on getting to best glide after engine failure. I'm not saying to glide at Vx, Vy or Vcc. At Vcc suffering an engine failure you'll be at best glide without much input in a few seconds, probably before the pilot can react, depending on the plane and how fast Vcc was of course. At a safe altitude, doing some engine failure simulation in a climb one can see how fast airspeed drops in the first 3 second. At Vy you'll have to actively (not shoving it though) push the nose down to not go below best glide. I can't speak for all aircraft types though.
Time to get my Vy tattoo
Also all of the v speeds change with altitude, temperature and weight.
I use GE all the time. "Free" energy before i pull up
The one that keeps you alive…..
Speed is life
Altitude is safety
Good points. For 17,000 hours I lived with less than 200' of altitude. Airspeed is life down here. Airspeed, zoom reserve airspeed, enough airspeed to maneuver without doubt, saved me eleven times when the engine failed there. Yes, altitude is safety. It is also time. Some of my low altitude forced landings would not have been necessary with more time to evaluate. Mine were all six second deals. I went to survivable landing zones in the very near hemisphere in front of the wing. It usually took full flaps and one rudder pedal to the stop forward slip to get into the beginning of those LZs. High altitude orientation (altitude is best, checklist, settle down and work it out, best glide airspeed) will kill you down here.
@@jimmydulin928 cropduster?
@@jimmydulin928 I'm not a pilot, crop-dusting was all I could think of to get that number of hours at that low of an altitude.
@@stephenalexander6721 Army helicopters, crop dusting, and pipeline patrol.
@@jimmydulin928 my hat is off to you and than you for what you've done.
The faster you go, the sooner you get to the rocks
Vy
At Vx you will have more altitude, NOT LESS ALTITUDE AS YOU PRESENTED..
Best rate of climb (Vy) will produce the fastest climb. "Best rate" means higest fpm possible. Climbing at the highest angle possible (Vx, best angle of climb) will result in less rate of climb.
Vy is the best. Gain height quick at close to best glide speed.
Which climb airspeed is the safest ? What stupid question. There is no answer to that because each climb speed has it's purpose.
What would you have titled the video?
@@LetsGoAviateWhich climb speed for which conditions?
@@LTVoyager But everyone already knows which climb speed to do for which conditions. The focus here is more on safety.
@@LetsGoAviate I understand and my comment stands. If you have a short runway and need to clear 70’ trees at the end, Vx is much safer than a faster Vy. Different scenarios dictate which V speed is safest and it isn’t always the speed that is faster or has the lowest deck angle.
@@LTVoyager I mean, that goes without saying. You need to clear the trees amd don't have the option of doing anything other than Vx. And I thought I covered that when I said that Vx is used for obstacle clearance and why Vx works best for that. Doesn't change the point of the video though.
At 4:33 My VSI indicates considerably HIGHER FPM climb rate at Vx than Vy. Not lower climb than Vy as the author claims. In addition, an early Vx climb gives me more runway remaining and maybe other landing options for an early engine out...
Vx with a higher vertical speed than Vy is an Oxymoron. Vy is the best rate of climb, you can't climb faster than your fastest rate of climb. Whatever airspeed gives you the highest fpm gain, thats your Vy.
If you are at considerably less than gross weight, that is not surprising. The published Vx and Vy are at gross weight.
Look at the videos. Why do pilots wish to quickly get high enough for an inadvertent stall, which they are much nearer at slower airspeed, to be fatal? Too many stall/fall into the middle of a long runway. What kind of total energy management is that?