Testing glide rings- will we make it to the runway?

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  • Опубліковано 19 січ 2025

КОМЕНТАРІ • 60

  • @GreatDataVideos
    @GreatDataVideos 6 днів тому +14

    If I remember correctly, they used to say that you could glide 2 miles for every 1,000 feet of altitude. Never believed it. Had the oil temperature redline on me when I was at 17,000 feet one time and had to pull the power back and glide to an airport. Made sure that I had plenty of altitude and then did a forward slip to loose the excess altitude. I would rather land in a field than try to stretch a glide.

    • @OneAlphaMike
      @OneAlphaMike 5 днів тому +8

      Who's "they" and what airplane? Some airplanes will easily glide 2 miles for every 1,000', some even more, but many others have much worse glide ratios. Gotta know your plane.

    • @GreatDataVideos
      @GreatDataVideos 5 днів тому

      @@OneAlphaMike I had a Saratoga II. I believe that I heard that from a couple of instructors.

    • @jetjock60
      @jetjock60 5 днів тому +3

      @@GreatDataVideos What does your P.O.H. say? Start there, not from a person who may or may not be "familiar" with your airplane. Are the published values with a windmilling prop, or with the prop at fine pitch (i.e. high pitch/ low RPM position)? are you gliding into the wind or with a tailwind. Also, your gross weight will affect both your glide speed and range.

    • @olympiashorts
      @olympiashorts 5 днів тому +2

      That’s a 12:1 glide ratio (if we’re talking nautical miles). I’m not sure that there are many piston engine aircraft that can do that. Sounds like glider performance.

    • @Skepilot
      @Skepilot 5 днів тому +8

      @@olympiashorts Sling TSi has a 12:1 glide ratio. Diamond Katana DA20-A1 has a glide ratio of 14:1. That's nowhere near gliders, which generally fall within a range of 30:1 to 60:1 for modern sailplanes.

  • @joegieseke1817
    @joegieseke1817 5 днів тому +5

    I wish he would have adjusted the L/D numbers on the foreflight program to show that the ring can reflect the airplanes performance if configured correctly.

  • @fdtank81
    @fdtank81 5 днів тому +4

    An iterative procedure to configure the ForeFlight settings to make glide range accurate would be useful

  • @pfflying6275
    @pfflying6275 4 дні тому +1

    In the Bonanza, I was always taught to estimate if a spot was within glide distance by seeing if the desired spot was below the wingtip as I looked left or right from the cockpit. When in other planes, I figure one mile for each 1,000 feet on the altimeter (In my area of the country the terrain is about 500 to 800 MSL). That always felt conservative, so was surprised when you were 5 miles at 5,000 feet and couldn't make it. Interesting video. Great idea for all pilots to test that out in our birds.

  • @CLdriver1960
    @CLdriver1960 2 дні тому +1

    The actual glide ratio on your Bonanza could also have been affected by: windmilling prop, additional antennas, misaligned landing gear doors, gap seals, airfoil contamination (bugs on the leading edge, especially for laminar flow airfoils), etc. Everything makes a difference.

  • @jonathantrunz4482
    @jonathantrunz4482 3 дні тому +1

    You HAVE to set up for YOUR airplane! I use it on a Garmin G3X and a light sport and it works perfect because I tested the actual sink right etc. and entered those numbers appropriately. I have tested it numerous times and it’s worked perfectly every time.

  • @AV8R_1
    @AV8R_1 5 днів тому +4

    Many pilots also forget that power off and idle power (simulated power off) are quite a bit different. Also, POH numbers and reality often differ as well, so supplying those numbers to the systems may not help much either. What Garmin and/or ForeFlight need to do is allow you to fly to a set altitude, and record the glide profile as you simulate power off descent at your best glide speed. It should be able to track your descent rate, distance traveled laterally between two known altitudes, and factor in the wind vector if it is known. Many advanced Garmin systems calculate wind vector already. After one or more of these test and recording sessions, performing these power off descents from, say, 8000 down to 3000 feet, the system should be able to extrapolate enough from the recorded data to very accurately postulate a predictable and reliable glide performance, and use that information to display more accurate glide rings.

    • @erickborling1302
      @erickborling1302 4 дні тому +1

      That's a dangerous rule of thumb: "POH numbers and reality often differ"

    • @GreatDataVideos
      @GreatDataVideos 4 дні тому +1

      When I get my next plane, I plan on doing these types of tests so that I have a rough idea of what to expect.

    • @AV8R_1
      @AV8R_1 4 дні тому

      @@erickborling1302 doesn't make it untrue. Ask any experienced pilot. POH numbers are derived using a brand new aircraft with a highly skilled and experienced test pilot flying in very specific atmospheric conditions. Many tables in the POH allow for calculated adjustments to the published numbers based on known differences such as temperature or density altitude, but they cannot account for differences in every case. They don't take into account pilot skill level. A perfect example was the Sully case. All the "experts" using simulators and POH published numbers insisted that from the point where he lost his engines he absolutely should have been able to make a runway. But reality, injected with chaos theory, produced a different result. None of the simulations or POH accounted for the time it took for him to assess the situation, make a decision, and put that decision into play. Along with numerous other human factors. I've been a private pilot for almost 20 years, I'm a commercial and instrument rated helicopter pilot, and at the moment I fly an American legend super cub. It has a published full flaps stall speed of 23 knots, but I have recorded video where I sustained flight for about five minutes indicating well below 23 knots, (in fact my air speed indicator went to zero) and I sustained level flight at 1800 RPM in a 10 knot wind on the nose. Zero ground speed. So effectively, I was flying straight and level at 10 knots, and still had not stalled. Published numbers are a very good guide, but they are not 100% accurate in all circumstances. That was my point.

  • @HyperSpaceProphet
    @HyperSpaceProphet 4 дні тому +2

    Now that video, rather than being a "Feel Good: story, was actually a useful one. A much better use of the AOPA money than most of the others that have recently been [produced.

  • @mojah1
    @mojah1 5 днів тому +5

    relying on manufacturers data could end up a broken promise
    Practice and mastering your equipment is a huge contribution to a successful execution among other factors

  • @itsaplane
    @itsaplane 2 дні тому

    I’ll add to the discussion as a 2000 hour sailplane pilot and a moderate time power pilot.
    About the worst thing you can do as pilot of either is stretch a glide, not make it, and be forced to land where you simply run out of altitude - almost a random spot that will be likely unfriendly. Much better is to pick a good spot and land well.
    Secondly, I would use glide rings, but lend credence to them only if I calibrated them to the performance of my airplane. You can test glide angle at idle power (miles made per thousand feet of descent and probably use this value). Hopefully the real glide angle in an emergency will be close to that (better if the prop stops, worse if heavier, etc.).
    But, with or without a fancy screen in the sailplane (they’re there too) or a power plane turned glider 😮 the best method may be knowing:
    1) how many miles per thousand feet of altitude your plane will glide,
    2) your altitude
    3) your distance from the runway and its elevation.
    Very quickly (and that’s the key) you can make that calculation and make a plan.
    Example: let’s say a power plane is known to glide 1 nm per thousand feet. I’m 5 nm out at 7500 feet, the airport is at 1,000 MSL: it’ll take 5000 to get there, I’ve got 6000. That sounds good! You may need to add drag (when you’ve got it made) or, even better, make something like a normal pattern for your best chance at a good landing.
    Note that wind, weight, bugs, scary terrain before the runway and other factors will change your glide angle calculations (use a lower miles-per-thousand feet of altitude to be more conservative). If you are conservative in the number you use then the complicating factors should mostly wash out.
    In my sailplane (ASW-27, look it up 😃) I mostly use 6 nm per thousand. With a typical final glide in the 50 nm range I need a little less than 10,000 feet to make it to the airport *with* a thousand foot pattern. And yes, during that glide I’m constantly running that miles-per-thousand calculation in my head and always have plans B and C if I’m falling short. ER

  • @SR22T_Pilot
    @SR22T_Pilot 5 днів тому +3

    Finally useful content! Thank you

  • @johnh9637
    @johnh9637 5 днів тому +1

    It appears range rings for ForeFlight should start with a very conservative estimate of glide ratio to be useful. It would be interesting to retest ForeFlight after entering a ratio 50% less than POH value.

  • @jimimmler9110
    @jimimmler9110 3 дні тому

    This information is indispensable. I have often wanted to test my Smart glide in the exact way you have just done. Obviously there is no way for any equipment to anticipate the decay or increase in winds as you descend to your decision point.

  • @rickjunkin6092
    @rickjunkin6092 3 дні тому

    Thanks for an excellent report Dave. You stopped short of saying, "They don't work", which I appreciate. A general recommendation of what to do to make the glide rings more accurate would be helpful. Some of the comments contain reasonable recommendations along these lines. This is real world stuff and a recommendation to enter a mid-range GW best glide speed and a maximum glide distance decreased by at least X% in each of these systems would point folks in the right direction for making the tools much more useful. This is no different than recommending a buffer of 50% on POH takeoff and landing data. I've done the same tests you did for this report and adjusted the values in Foreflight and on my G3X to give me accurate glide rings in which I have confidence. As you demonstrated, if you want to confidently use Smart Glide the best glide speed and glide ratio entered into the system must be conservatively adjusted from the POH values.

  • @dh-flies
    @dh-flies 3 дні тому +1

    You don't need that Smart Glide button. Just hold down Direct To for a few seconds and it engages.

  • @RVFlyer
    @RVFlyer 4 дні тому

    Nice job Dave, excellent demo.

  • @rogerblack4603
    @rogerblack4603 5 днів тому +3

    I wonder what factors the initial calculation includes (eg glide polar, wind velocity, dead stick or free wheeling prop)

  • @zidoocfi
    @zidoocfi 5 днів тому +1

    🚨At Oshkosh and Sun-N-Fun forums I have already been teaching that these glide rings are about 10 to 20 percent too optimistic primarily because "Best Glide Speed" is only valid for a specific weight, configuration, and wind. The glide rings generally do an okay job with wind, and configuration isn't too far off, but most pilots do not understand the glider pilot concept of "speed to fly" which adjusts glide speed for the weight. Those tests in the Bonanza and RV were flown too fast for the weight and hence glide performance was PREDICTABLY poorer than expected. I recommend that most pilots adjust their glide ratio in ForeFlight down by about 10 to 20 percent so as to get realistic expectations.

  • @mwalloch
    @mwalloch 5 днів тому +2

    With a dead engine, pulling the prop back will not do anything because there won’t be any oil pressure, thus both Lycoming and Continental recommend against this procedure in simulated engine-out practice.

    • @wolfkin73
      @wolfkin73 5 днів тому +2

      Worse. Moving the prop to low RPM with no oil pressure will dump the oil out of the hub. Resulting in an increase in RPM and drag associated. Ask me how I know…

    • @pumpkinferret
      @pumpkinferret 5 днів тому +1

      @@wolfkin73 I’m genuinely curious on what made you find that out, if you wouldn’t mind sharing lol

    • @wolfkin73
      @wolfkin73 4 дні тому +2

      @ oil pressure loss in a Cessna 185 and following loss of power (valves not opening from collapsed lifters?) ran the typical set of rich/lean, fuel pump on/off to see if I could get any improvement. When a rod snapped I thought I’d try the prop to reduce that drag. Big mistake. Blades went to fine pitch and I had a 2500fpm decent at best glide. I walked away without injury but aircraft not so much.

    • @mwalloch
      @mwalloch 4 дні тому +1

      @@pumpkinferret just conversations with high-hour pilots who know a lot more than me.

    • @mwalloch
      @mwalloch 4 дні тому +1

      @@wolfkin73 Exactly! Thanks for sharing.

  • @markpeterson6924
    @markpeterson6924 2 дні тому

    You have to add traffic pattern altitude as a safety factor to set up an approach with margins. I wonder if glide rings are a reason so many planes crash a mile short.

  • @PilotPlater
    @PilotPlater 5 днів тому

    I've heard atc audio where the pilot saw his range ring getting smaller and decided not to try and stretch the glide - very likely it saved his life, as you say bought him that realization early so he set up for off-airport landing sooner.

    • @erickborling1302
      @erickborling1302 4 дні тому

      There is no stretch. Though you can get another 50 of float if you deploy flaps at the last couple seconds.

  • @The_Flying_Mechanic
    @The_Flying_Mechanic 5 днів тому +2

    Did you modify your published best glide speed? Just you in the aircraft will drastically bring down the Vg. You can solve for the current Vg by multiplying the punlished Max Gross Vg by the square root of your actual weight/MTOW. I think you'll find your real Vg should have been about 98 knots given your scenario and THAT is why the glide ring shrank.

  • @katiepribyl
    @katiepribyl 4 дні тому

    Super useful video!

  • @u2fletch
    @u2fletch 4 дні тому +2

    Garbage in, garbage out. If the glide numbers in the system are not accurate, then of course they won’t work. I programmed my G3X with real world numbers that should display much more accurate glide rings.

  • @nelsonbrandt7847
    @nelsonbrandt7847 5 днів тому

    Awesome video!

  • @jetjock60
    @jetjock60 5 днів тому

    I'm curious if these systems are factoring wind, i.e. groundspeed into the equation, not just the entered values for best glide speed and glide ratio from the P.O.H.

    • @johnh9637
      @johnh9637 5 днів тому

      ForeFlight display includes the effect of wind. I'm not sure if the wind is estimated from FD forecast or in-flight measurement.

  • @xenadu02
    @xenadu02 5 днів тому +2

    Best glide is only valid at max gross. If you're under weight your nominal best glide will be too fast and as a result you won't glide as far.
    Remember too fast and you come up short. Too slow and you come up even shorter. You can verify this by checking your vertical speed (at a safe altitude). You can see that if you go too fast or slow your sink rate increases.

    • @luisputzeys
      @luisputzeys 5 днів тому

      Also varies by headwind/tailwind component.

    • @jonathanshill8624
      @jonathanshill8624 4 дні тому

      It's always hard to judge accurately from action cams, but looking at the wing of the Bonanza on approach it looked like the AoA was way too low to be close to Best Glide speed for his aircraft weight at the time. Too bad the Garmin system can't just fly a best glide AoA.

  • @seanmarshall7608
    @seanmarshall7608 5 днів тому +4

    Aren't we just supposed to pull a parachute handle nowadays?😁

    • @scarybaldguy
      @scarybaldguy 5 днів тому

      NTSB final: "Loss of aircraft control due to PIC distraction looking for the BRS handle in his Cherokee 180."

    • @erickborling1302
      @erickborling1302 4 дні тому

      No!

  • @luisputzeys
    @luisputzeys 5 днів тому

    The best glide ring app I’ve ever seen is Xavion. It’s designed so that you aren’t flying at best glide speed. Sounds counterintuitive but it’s actually safer versus trying to maximize your glide when you or the airplane will not be able to get the same performance when the plane was certified, as this video demonstrates.
    ua-cam.com/video/L75FaVFQeXg/v-deo.htmlsi=zvVTwFnaMttQsEBp

  • @Thegr8iam-p7t
    @Thegr8iam-p7t 5 днів тому

    This technology if not used correctly will kill more people than it will save. Because the best solution to an engine failure is to already have a plane to where a possible walk away ditching will take place. Good airmen have ongoing plans before flying and while flying they update plans. It takes lots of work a good work ethic to stay alive and not damage an airframe or kill yourself or others.

    • @jimimmler9110
      @jimimmler9110 3 дні тому +1

      No technology should ever be considered as a replacement to good pilot skill. A good pilot needs to know how to use all tools to their advantage.

  • @TylerN737s
    @TylerN737s 5 днів тому

    Find your power off glide ratio, half it & deduct 10%. Probably still won’t make it.

  • @texasflyer3830
    @texasflyer3830 2 дні тому

    Why are you starting each example with the airport outside the range ring in the video, then showed you couldn’t make it? A better video would be how to customize each for actual glide performance then demonstrate it DOES work.

  • @professionalantivaxxer4065
    @professionalantivaxxer4065 5 днів тому

    Are we still fixated on this impossible turn? Come on. That’s been tested thoroughly

    • @scarybaldguy
      @scarybaldguy 5 днів тому +2

      Where did you see any mention of the impossible turn any time in this video or the description?

  • @mts982
    @mts982 5 днів тому

    dont slow so much or dip so much.

    • @cgtbrad
      @cgtbrad 5 днів тому

      best glide speed is tested and determined by the aircraft manufacturer. It can vary with aircraft weight and wind speed/direction. But generally, the value determined by the manufacturer is pretty close!