The Impossible Turn...

[rv8ch]

Larry and Norman,

The demo in the vid is a snap departure (a semi-horizontal spin, if you will). It’s purely for demo and instructional use. It’s the result of just enough adverse yaw (skid) to induce a snap roll. The electronic ball isn’t that great, but in its defense the amount of aileron applied is so slight it’s hard to detect. RV’s have Hershey bar wings, so the stall happens quickly and without much aerodynamic warning, which is why proper coordination is so important. The airplane is much more departure resistant in a slip (but will eventually depart if you force it). If you haven’t had spin training, it’s definitely worth the time in any suitable airplane with a qualified instructor. The reason I teach this departure mode (at altitude) is because it happens so quickly, it helps to experience it real-time. The airplane goes from controlled flight to uncontrolled flight quickly. If you were to overshoot final, and make this handling error at 300’ or so, the ground is probably going to get in the way of recovery.

Good discussion, and still pertinent to aircraft handling during a power loss on takeoff. More folks lose control on takeoff and departure than during approach and landing.

Fly safe,

Vac

That's a very powerful demonstration of how quickly we can get in trouble. And the conditions for this are very common, at least in my experience. Rarely does it happen when you do everything the same way, and are alone in the pattern. It's when you are going to a fly-in, or the pattern is very busy, or a slow aircraft cuts you off, or ATC asks for a 360 for spacing, or some other non-standard event. You stop thinking about flying the aircraft for just a moment, and then you're a smoking heap in a cornfield.

Thanks for producing and sharing these videos, Vac!

 

[lr172]

Larry and Norman,

The demo in the vid is a snap departure (a semi-horizontal spin, if you will). It’s purely for demo and instructional use. It’s the result of just enough adverse yaw (skid) to induce a snap roll. The electronic ball isn’t that great, but in its defense the amount of aileron applied is so slight it’s hard to detect. RV’s have Hershey bar wings, so the stall happens quickly and without much aerodynamic warning, which is why proper coordination is so important. The airplane is much more departure resistant in a slip (but will eventually depart if you force it). If you haven’t had spin training, it’s definitely worth the time in any suitable airplane with a qualified instructor. The reason I teach this departure mode (at altitude) is because it happens so quickly, it helps to experience it real-time. The airplane goes from controlled flight to uncontrolled flight quickly. If you were to overshoot final, and make this handling error at 300’ or so, the ground is probably going to get in the way of recovery.

Good discussion, and still pertinent to aircraft handling during a power loss on takeoff. More folks lose control on takeoff and departure than during approach and landing.

Fly safe,

Vac

Thanks so much for the explanation. Could you explain what your recovery procedure was in this video? I noticed that you were mostly straight down when the rotation stopped.

 

[Vac]

Thanks so much for the explanation. Could you explain what your recovery procedure was in this video? I noticed that you were mostly straight down when the rotation stopped.

Larry,

Stick forward (reduce AOA), rudder opposite rotation. I don't want to get into a deep discussion about spin recovery, but I always start any recovery with an "unload for control" to reduce AOA and then go from there. That technique (starting with reducing AOA) works in any airplane, so it's a personal go-to first step since not all departures involve auto-rotation (swept wing jets would do some wonky things when they ran out of stability).

What's really nice about RV's, is how fast they start flying if you reduce AOA after asking the wing to work too hard. The wing stalls quickly, but it also starts flying quickly.

When we came up with the "airspeed only" technique of executing the turn-back at Vref, we "ops checked" the kinetic energy reserve (airspeed reserve! ) using tuft testing and FAR 23 stall warning criteria. In this test, I'm starting at Vref appropriate for gross weight, and walking the airplane into stall warning and stall so we could precisely measure AOA to determine what the buffer is with a basic stall warning system. This is good example of how a simple wing (constant chord, constant incidence, no taper or washout) stalls all at once, and also starts flying all at once. This is real-time video. The only difference between this test and the departure demo we are discussing is that I'm properly coordinating flight control inputs--both wings are stalling, vs the "departure" where only the left wing stalls as a result of adverse yaw. Again, the take-away is how fast this occurs:

Fly safe,

Vac

 

[rocketman1988]

Larry,

Stick forward (reduce AOA), rudder opposite rotation. I don't want to get into a deep discussion about spin recovery, but I always start any recovery with an "unload for control" to reduce AOA and then go from there. That technique (starting with reducing AOA) works in any airplane, so it's a personal go-to first step since not all departures involve auto-rotation (swept wing jets would do some wonky things when they ran out of stability).

What's really nice about RV's, is how fast they start flying if you reduce AOA after asking the wing to work too hard. The wing stalls quickly, but it also starts flying quickly.

When we came up with the "airspeed only" technique of executing the turn-back at Vref, we "ops checked" the kinetic energy reserve (airspeed reserve! ) using tuft testing and FAR 23 stall warning criteria. In this test, I'm starting at Vref appropriate for gross weight, and walking the airplane into stall warning and stall so we could precisely measure AOA to determine what the buffer is with a basic stall warning system. This is good example of how a simple wing (constant chord, constant incidence, no taper or washout) stalls all at once, and also starts flying all at once. This is real-time video. The only difference between this test and the departure demo we are discussing is that I'm properly coordinating flight control inputs--both wings are stalling, vs the "departure" where only the left wing stalls as a result of adverse yaw. Again, the take-away is how fast this occurs:

Fly safe,

Vac

Yep, unloading the wing really helps. I would, however, be careful with terms like "stick forward" as personal experience has shown that can lead to rather exciting events. It doesn't take much to unload the wing and you can get yourself into a whole other situation by over controlling.

My son, while instructing a basic student, was doing stall work which he demonstrated. When it was the students turn, he pushed the yoke on the 172 forward so hard that it broke the plastic bushing around the yoke column! Yeehaw!

 

[lr172]

Larry,

Stick forward (reduce AOA), rudder opposite rotation. I don't want to get into a deep discussion about spin recovery, but I always start any recovery with an "unload for control" to reduce AOA and then go from there. That technique (starting with reducing AOA) works in any airplane, so it's a personal go-to first step since not all departures involve auto-rotation (swept wing jets would do some wonky things when they ran out of stability).

What's really nice about RV's, is how fast they start flying if you reduce AOA after asking the wing to work too hard. The wing stalls quickly, but it also starts flying quickly.

When we came up with the "airspeed only" technique of executing the turn-back at Vref, we "ops checked" the kinetic energy reserve (airspeed reserve! ) using tuft testing and FAR 23 stall warning criteria. In this test, I'm starting at Vref appropriate for gross weight, and walking the airplane into stall warning and stall so we could precisely measure AOA to determine what the buffer is with a basic stall warning system. This is good example of how a simple wing (constant chord, constant incidence, no taper or washout) stalls all at once, and also starts flying all at once. This is real-time video. The only difference between this test and the departure demo we are discussing is that I'm properly coordinating flight control inputs--both wings are stalling, vs the "departure" where only the left wing stalls as a result of adverse yaw. Again, the take-away is how fast this occurs:

Fly safe,

Vac

Thanks Vac! Good to know basic recovery techniques work in that situation. I feel that i am mentally prepared for the day it happens, but I guess you never know until thrown into the situation. Now on my short term bucket list to do this with someone experienced soon. Kinda funny that my son in training has more spin experience than me. He has done all his training in our 6. He got so used to the left wing dropping in a stall that right rudder became rote behavior. One day it dropped the right wing, but he still put in right rudder out of habit. Instructor fixed it quickly. These planes are really fun to fly because everything happens so quick, but I guess there is danger in that as well.

 

[Notso]

Sorry to resurrect an old(ish) thread.... But several weeks ago, a group of RV pilots at my patch got to talking about the "impossible turn" and how to do it. What spurred that discussion was one of them mentioned that the FAA now supposedly endorses CFIs adding the impossible turn to their teaching bag of tricks. So we all wondered how we would do it in our RV's. One member of the group @Taltruda said he had already done some practice, so I wanted to go try for myself. I had a cool new Insta360 camera to try out - so I thought I would film it as I went and pass lessons learned back to the group. I was wavering on whether to start a new thread and post them here - but I just discovered that this thread existed using a search. I wish I had seen this before I started the tests. But in any event the tests were very illuminating and maybe someone can get something out of the videos.

First of all - I want to be VERY CLEAR upfront: If you have ANY thought of trying this out and putting it in your "emergency tool bag" - you need to go try this in YOUR airplane. Every airplane is different!! And especially don't think you can do the impossible turn without practice, practice, practice!! This is NOT something you are going to invent the first time if the gods forbid your engine quits on takeoff one day. My pitch is you need to practice this AND you need to think through how you're going to do it before EVERY takeoff! Every time! Essentially brief it to yourself while holding short.... what am I going to do IF____. What directly would I turn, where are the obstacles to take into consideration.

As has been stated here before - I started this journey at a safe altitude and used a set altitude on the altimeter to simulate the runway level and then practiced turns back to that altitude before I was comfortable doing it back to a real runway. However, one lesson I learned is if you're going to practice - I suggest finding an actual runway (or road) that you can fly directly over at like 1500-2000AGL so you have a visual reference to line up on when coming back around. I found it VERY difficult to just simulate this by flying a heading out in some nebulous area. After a couple of tries over nothing, I moved to directly over a real runway and that made the practice SOOO much better.

Eventually, I was comfortable enough that I wanted to try to do this and land on the runway. My parameters and lessons learned were:

• Accomplished a touch n go and then set a pitch attitude to maintain a standard 110kt Climb profile until a specific AGL altitude where the engine "quit". I chose 110kts because that is kinda the standard here where because of the summer time temps here in Vegas, we generally keep the nose down to stay faster to get better cooling. I think if I had done a Vx or Vy climb profile, I'd probably have even more altitude to play with and be closer to the runway.
• I included a 3 second "startle factor" before making any moves back to the runway.
• One thing I found that was critical was to keep the nose up until you bled your airspeed down to glidespeed. Most people would immediately jam the nose down, but at 100+ kts - imho you're giving away energy unnecessarily.
• My goal was to maintain 85kts (my Vg) +/- 5kts. So typically between 80-85 KIAS was where I lived most of the time. USE YOUR OWN Numbers!!
• I found you had to be fairly aggressive and get at least a 45 deg bank and sometimes approaching 60 deg and around 2Gs to make it back to the runway. Anything "lazier" and you would float too far away.
• If there are any crosswinds - turn INTO the wind to make your turn radius as small as possible. Turning away from the wind would screw you big time.
• Turn directly to the runway and aim about 1/3 of the way down. Don't try to line up on final unless and until you know you have excess energy to trade for distance.
• I did progressive attempts at 1000 AGL, 500 AGL, 300 AGL and 100 AGL. I felt the 1000 and 500 were "comfortable". The 300 AGL return was doable if you were on your game. The 100 AGL was white knuckle and you had no startle factor time. I only made like 2 of 5 attempts at 100 AGL using that profile. If however I did the "zoom" profile that @Taltruda described - i.e. Stay i ground effect, accelerate and then pop aggressively at the end of the runway - then yet that excess speed could be converted to energy to turn around.
• I did almost all my tests at worst case - full fuel for the weight and I did NOT pull the prop lever to get better glide performance. I however did not try this with a pax.
• If you want to practice this, do it over a sparsely populated runway/airport.

Anywho, here are the videos with narration to describe what's going on. I've got my flame-proof suit on, so fire away.

500 AGL/110kts - 1st try:

500 AGL/110 kts - 2nd try:

300 AGL/110kts - 1st try:

300 AGL/110kts - 2nd try:

500 AGL Zoom:

300AGL Zoom: https://youtu.be/WxkaPkXRIgg

 

[Norman CYYJ]

Sorry to resurrect an old(ish) thread.... But several weeks ago, a group of RV pilots at my patch got to talking about the "impossible turn" and how to do it. What spurred that discussion was one of them mentioned that the FAA now supposedly endorses CFIs adding the impossible turn to their teaching bag of tricks. So we all wondered how we would do it in our RV's. One member of the group @Taltruda said he had already done some practice, so I wanted to go try for myself. I had a cool new Insta360 camera to try out - so I thought I would film it as I went and pass lessons learned back to the group. I was wavering on whether to start a new thread and post them here - but I just discovered that this thread existed using a search. I wish I had seen this before I started the tests. But in any event the tests were very illuminating and maybe someone can get something out of the videos.

First of all - I want to be VERY CLEAR upfront: If you have ANY thought of trying this out and putting it in your "emergency tool bag" - you need to go try this in YOUR airplane. Every airplane is different!! And especially don't think you can do the impossible turn without practice, practice, practice!! This is NOT something you are going to invent the first time if the gods forbid your engine quits on takeoff one day. My pitch is you need to practice this AND you need to think through how you're going to do it before EVERY takeoff! Every time! Essentially brief it to yourself while holding short.... what am I going to do IF____. What directly would I turn, where are the obstacles to take into consideration.

As has been stated here before - I started this journey at a safe altitude and used a set altitude on the altimeter to simulate the runway level and then practiced turns back to that altitude before I was comfortable doing it back to a real runway. However, one lesson I learned is if you're going to practice - I suggest finding an actual runway (or road) that you can fly directly over at like 1500-2000AGL so you have a visual reference to line up on when coming back around. I found it VERY difficult to just simulate this by flying a heading out in some nebulous area. After a couple of tries over nothing, I moved to directly over a real runway and that made the practice SOOO much better.

Eventually, I was comfortable enough that I wanted to try to do this and land on the runway. My parameters and lessons learned were:

• Accomplished a touch n go and then set a pitch attitude to maintain a standard 110kt Climb profile until a specific AGL altitude where the engine "quit". I chose 110kts because that is kinda the standard here where because of the summer time temps here in Vegas, we generally keep the nose down to stay faster to get better cooling. I think if I had done a Vx or Vy climb profile, I'd probably have even more altitude to play with and be closer to the runway.
• I included a 3 second "startle factor" before making any moves back to the runway.
• One thing I found that was critical was to keep the nose up until you bled your airspeed down to glidespeed. Most people would immediately jam the nose down, but at 100+ kts - imho you're giving away energy unnecessarily.
• My goal was to maintain 85kts (my Vg) +/- 5kts. So typically between 80-85 KIAS was where I lived most of the time. USE YOUR OWN Numbers!!
• I found you had to be fairly aggressive and get at least a 45 deg bank and sometimes approaching 60 deg and around 2Gs to make it back to the runway. Anything "lazier" and you would float too far away.
• If there are any crosswinds - turn INTO the wind to make your turn radius as small as possible. Turning away from the wind would screw you big time.
• Turn directly to the runway and aim about 1/3 of the way down. Don't try to line up on final unless and until you know you have excess energy to trade for distance.
• I did progressive attempts at 1000 AGL, 500 AGL, 300 AGL and 100 AGL. I felt the 1000 and 500 were "comfortable". The 300 AGL return was doable if you were on your game. The 100 AGL was white knuckle and you had no startle factor time. I only made like 2 of 5 attempts at 100 AGL using that profile. If however I did the "zoom" profile that @Taltruda described - i.e. Stay i ground effect, accelerate and then pop aggressively at the end of the runway - then yet that excess speed could be converted to energy to turn around.
• I did almost all my tests at worst case - full fuel for the weight and I did NOT pull the prop lever to get better glide performance. I however did not try this with a pax.
• If you want to practice this, do it over a sparsely populated runway/airport.

Anywho, here are the videos with narration to describe what's going on. I've got my flame-proof suit on, so fire away.

500 AGL/110kts - 1st try:

500 AGL/110 kts - 2nd try:

300 AGL/110kts - 1st try:

300 AGL/110kts - 2nd try:

500 AGL Zoom:

300AGL Zoom: https://youtu.be/WxkaPkXRIgg

Yes and with the engine at idle no where is it like an actual engine out. You had better have significant more altitude before actually doing it. Unfortunately if the engine quits it is seldom at convenient altitude.

 

[glider_rider]

Yes and with the engine at idle no where is it like an actual engine out. You had better have significant more altitude before actually doing it. Unfortunately if the engine quits it is seldom at convenient altitude.

+1
Can’t really speak for other types but 14 is a lousy glider, landing engine off is significantly different than with engine at idle.
My personal preference is to use the AOA to make the turn.

 

[Notso]

Yes and with the engine at idle no where is it like an actual engine out. You had better have significant more altitude before actually doing it. Unfortunately if the engine quits it is seldom at convenient altitude.

Yep, understood.

One of the things a couple of us discussed is the mindset of landing straight ahead vs trying to make it back to the airport/Runway. Like our airport is surrounded by a fairly dense suburban environment. Sure there's roads. But there's powerlines along and crossing every road, lots of traffic and houses and such. The thought was even if you couldn't make it to the same runway - sometimes just getting back to the airport boundary might be better than going into a neighborhood. Like there's crossing runways, taxiways, ramps, and worst case lots of open ground without many tall structures. I feel like I'd rather try to make it at least back to the airport environment rather than into someone's kitchen. Or into 100ft tall pines trees, etc. Everyone's situation is different.

 

[Notso]

My personal preference is to use the AOA to make the turn.

How do you use AOA to make the turn?

 

[glider_rider]

How do you use AOA to make the turn?

To fly the turn as slow as possible, but not too slow. The goal is to achieve the minimum sink speed with a given bank angle.

 

[Fffflats]

How do you use AOA to make the turn?

Use minimum power required AOA at forty-five AOB for the turn then L/Dmax AOA for the straight. As you likely don’t know your min power req AOA, and as this is likely very close to stall, Vac and the Fly Onspeed organization recommend using onspeed AOA in lieu of it. Slightly less performance but better safety margin in execution. So onspeed AOA at 45 AOB for turn then L/Dmax AOA in the straight. If you’re slightly slow in the straight, as you’re now going with the wind, this is ok. But trying to figure out by how much is difficult, so easy, stick with L/Dmax.

 

[Ironflight]

Yep, understood.

One of the things a couple of us discussed is the mindset of landing straight ahead vs trying to make it back to the airport/Runway. Like our airport is surrounded by a fairly dense suburban environment. Sure there's roads. But there's powerlines along and crossing every road, lots of traffic and houses and such. The thought was even if you couldn't make it to the same runway - sometimes just getting back to the airport boundary might be better than going into a neighborhood. Like there's crossing runways, taxiways, ramps, and worst case lots of open ground without many tall structures. I feel like I'd rather try to make it at least back to the airport environment rather than into someone's kitchen. Or into 100ft tall pines trees, etc. Everyone's situation is different.

While I am vocally not a proponent of a turnback (have lost too many friends who have tried it - some of them VERY experienced pilots), I wish people would stop talking about “Straight” ahead! I prefer to simple use “land ahead” - which helps you think of anywhere within 90 degrees of runway heading, left or right. I totally agree that landing on the airport property (generally level and clear) is better than going in to houses, and a turn of 90 will greatly increase your options. The runway? Often that’s a pipe dream - and not required to survive. I know of actual friend’s accidents that wouldn’t have been fatal of they had taken that option.

And if there is truly no option for an engine failure at your airport….you have to ask why you;re using that airport! That is a decision that you have made that limits your options. It’s why, as a DAR, there are airports where we are not allowed to let folks do Phase 1.

 

[Taltruda]

+1
Can’t really speak for other types but 14 is a lousy glider, landing engine off is significantly different than with engine at idle.
My personal preference is to use the AOA to make the turn.

What propeller do you have, and have you tuned your low pitch stops? I can almost guarantee that they aren’t right if you just bolted it on out of the box.. it’ll glide MUCH better after you adjust them for 2650 statically.

 

[glider_rider]

What propeller do you have, and have you tuned your low pitch stops? I can almost guarantee that they aren’t right if you just bolted it on out of the box.. it’ll glide MUCH better after you adjust them for 2650 statically.

I have the fastest prop that one can get
And it’s adjusted properly

 

[ronrapp]

And if there is truly no option for an engine failure at your airport….you have to ask why you;re using that airport! That is a decision that you have made that limits your options.

Sometimes it's the only airport around. Or all the airports have that same issue. This is what comes of allowing development right up to the runway, unfortunately. Airpots all around my neck of the woods are like that: Fullerton, Compton, Cable, Santa Monica, Burbank, Whiteman, and more. Could you base your airplane elsewhere? Sure, but an hour or two drive each way to get to the plane means you'd stop flying pretty quickly. Could I base my plane at SNA instead? Sure, if I wanted to leave it outside and pay $500 a month for the privilege. Or pay $3,000 a month for a T-hangar, if I could get one. Which I can't.

Phase One flight test areas are a different story. The risk is higher with a newly built aircraft, especially as it's often accompanied by a rusty PIC with little time in the airplane, so it makes sense to limit the operation for those first critical hours.

This lack of space around the runway isn't just a problem in the U.S. I recall holding short of the runway at Congonhas Airport in São Paulo, Brazil and realizing that a guy standing on his apartment balcony could probably jump right onto my wing from where he stood. In fact, that sort of thing is almost the rule rather than the exception. I've run into the same thing in Russia, Ecuador, China, and elsewhere.

--Ron

 

[Vac]

NOTSO, great test work. The short answer to using AOA is just fly the entire thing on speed (maximum endurance glide). It's the best blend of overall performance, while maintaining a sufficient margin from stall. It's also an easy way to fly the airplane without having to hit multiple target airspeeds. It's already been pointed out, but you do have to figure out residual thrust at IDLE. With a fixed pitch prop, some additional drag is required to duplicate actual engine-off glide angle (e.g., flaps 40 in the RV-4, flaps 30 in a C172 etc.) for practice. With a constant speed prop, zero thrust works well.

One of things we learned in our research is that you must (I really mean MUST) use some sort of decision aid to be able to reliably do this under ambient conditions. In no way does this mean not practice (you are correct that the FAA is advocating it be taught, which is why we started the research in the first place) or experiment--I just means in the end, there is no "one size fits all" solution for any airplane under all conditions, it's simply too dynamic for the Mark I Eyeball/butt computer. An actual decision aid allows to you look at the picture BEFORE you takeoff and then provides GUIDANCE after the airplane starts moving.

Ron's point is spot on, and by looking at the picture before you take the active runway, you may find that your least bad option may be aft of the wing line, assuming sufficient altitude can be attained prior to the malfunction. Only a computer can paint that picture for you.

Here is the ultimate result of all of our homework. It's an IOS app (sorry android people ) called TLAR, military slang for "that looks about right." It's the expert version and you can access it at TLARPilot.com. It combines the aerodynamics of the airplane with real time load and ambient meteorological conditions. All of which are significant, with wind possibly the most significant. This version is designed for pre-flight and in-flight use. For preflight, the pilot inputs the specifics (airplane type, weight, fuel load, airport/runway) and then either integrates METAR data or manually inputs temperature, altimeter setting, elevation and wind direction and speed. The system then calculates basic takeoff, climb, cruise and landing performance (distances, configuration, target airspeeds and fuel flow). This is an example for a C172M using runway 5 at KOSH today (on the frozen tundra, where the local temp is the Greek letter "zero" ). This big negative density altitude means the airplane has some really good performance at light weight:



In this example, Flaps 10 takeoff ground roll is 440' with 670' required to clear a fifty foot obstacle. A Vy climb will occur at 71 KCAS, and the airplane will climb at 1268 FPM. 65% cruise will net 111 KTAS and 9.1 GPH. A Flaps 40 landing will require 1330 feet over a fifty foot obstacle, with a ground roll of 360 feet. Different parameters can be adjusted (just like an APS or "aircraft performance system" for folks that are used to flying big jets) so you can what-if different takeoff and landing configurations, climb and cruise techniques. You can also "manually over-ride" any of the METAR data, so lets manually input 15 deg C and 29.92 that it isn't quite so North Pole before we look at takeoff planning:



This is a bit more realistic, since I know I'm not inclined to push the airplane out of the hangar at -16! Now let's look at takeoff decision making. This next pic is the "sky" mode. If you look at runway 5, the white dot is liftoff, and the end of the white arrow is the distance at which the airplane will get to 50'. You can see the wind arrow showing a quartering headwind from the left. The yellow X is the last point at which we can land straight ahead AND REMAIN ON THE RUNWAY if the engine fails. The green dot is the point at which the airplane will get to minimum turn back altitude (1130' MSL in this example). The various parameters the computer is using are shown on the display, so if you want to adjust the angle of bank from optimum, etc., go ahead and you can see how that effects performance:



Now let's go to a summer-time scenario and raise the zero fuel weight of the airplane and look at what our options are if we decide to use Runway 5 under these conditions. Notice that we don't have a lot of options if we have a problem on Runway 5. That's fine--it's just physics. Now we know we may want to select a different runway (36 would be a good option) if that's available. Perhaps we want to off-load some fuel or payload, etc. But the bottom line is that the first time we are thinking about whether or not a turn-back is even an option isn't after the airplane is airborne. We know from mishap statistics that a lot of people don't, since fully 25-30% of turn-back attempts are started at 200' AGL or less; and there isn't an airplane in the world (apologies to the glider and ultra-light folks!) that can do that:



In the next post, we'll walk through engine failure scenarios at low and high altitude using the computer vs. the Mark I eyeball.

Fly safe,

Vac

 

[Dugaru]

NOTSO, great test work. The short answer to using AOA is just fly the entire thing on speed (maximum endurance glide). It's the best blend of overall performance, while maintaining a sufficient margin from stall. It's also an easy way to fly the airplane without having to hit multiple target airspeeds. It's already been pointed out, but you do have to figure out residual thrust at IDLE. With a fixed pitch prop, some additional drag is required to duplicate actual engine-off glide angle (e.g., flaps 40 in the RV-4, flaps 30 in a C172 etc.) for practice. With a constant speed prop, zero thrust works well.

One of things we learned in our research is that you must (I really mean MUST) use some sort of decision aid to be able to reliably do this under ambient conditions. In no way does this mean not practice (you are correct that the FAA is advocating it be taught, which is why we started the research in the first place) or experiment--I just means in the end, there is no "one size fits all" solution for any airplane under all conditions, it's simply too dynamic for the Mark I Eyeball/butt computer. An actual decision aid allows to you look at the picture BEFORE you takeoff and then provides GUIDANCE after the airplane starts moving.

Ron's point is spot on, and by looking at the picture before you take the active runway, you may find that your least bad option may be aft of the wing line, assuming sufficient altitude can be attained prior to the malfunction. Only a computer can paint that picture for you.

Here is the ultimate result of all of our homework. It's an IOS app (sorry android people ) called TLAR, military slang for "that looks about right." It's the expert version and you can access it at TLARPilot.com. It combines the aerodynamics of the airplane with real time load and ambient meteorological conditions. All of which are significant, with wind possibly the most significant. This version is designed for pre-flight and in-flight use. For preflight, the pilot inputs the specifics (airplane type, weight, fuel load, airport/runway) and then either integrates METAR data or manually inputs temperature, altimeter setting, elevation and wind direction and speed. The system then calculates basic takeoff, climb, cruise and landing performance (distances, configuration, target airspeeds and fuel flow). This is an example for a C172M using runway 5 at KOSH today (on the frozen tundra, where the local temp is the Greek letter "zero" ). This big negative density altitude means the airplane has some really good performance at light weight:

View attachment 108552

In this example, Flaps 10 takeoff ground roll is 440' with 670' required to clear a fifty foot obstacle. A Vy climb will occur at 71 KCAS, and the airplane will climb at 1268 FPM. 65% cruise will net 111 KTAS and 9.1 GPH. A Flaps 40 landing will require 1330 feet over a fifty foot obstacle, with a ground roll of 360 feet. Different parameters can be adjusted (just like an APS or "aircraft performance system" for folks that are used to flying big jets) so you can what-if different takeoff and landing configurations, climb and cruise techniques. You can also "manually over-ride" any of the METAR data, so lets manually input 15 deg C and 29.92 that it isn't quite so North Pole before we look at takeoff planning:

View attachment 108553

This is a bit more realistic, since I know I'm not inclined to push the airplane out of the hangar at -16! Now let's look at takeoff decision making. This next pic is the "sky" mode. If you look at runway 5, the white dot is liftoff, and the end of the white arrow is the distance at which the airplane will get to 50'. You can see the wind arrow showing a quartering headwind from the left. The yellow X is the last point at which we can land straight ahead AND REMAIN ON THE RUNWAY if the engine fails. The green dot is the point at which the airplane will get to minimum turn back altitude (1130' MSL in this example). The various parameters the computer is using are shown on the display, so if you want to adjust the angle of bank from optimum, etc., go ahead and you can see how that effects performance:

View attachment 108555

Now let's go to a summer-time scenario and raise the zero fuel weight of the airplane and look at what our options are if we decide to use Runway 5 under these conditions. Notice that we don't have a lot of options if we have a problem on Runway 5. That's fine--it's just physics. Now we know we may want to select a different runway (36 would be a good option) if that's available. Perhaps we want to off-load some fuel or payload, etc. But the bottom line is that the first time we are thinking about whether or not a turn-back is even an option isn't after the airplane is airborne. We know from mishap statistics that a lot of people don't, since fully 25-30% of turn-back attempts are started at 200' AGL or less; and there isn't an airplane in the world (apologies to the glider and ultra-light folks!) that can do that:

View attachment 108557

In the next post, we'll walk through engine failure scenarios at low and high altitude using the computer vs. the Mark I eyeball.

Fly safe,

Vac

This is totally awesome!!! If I make a special donation to VAF in gratitude, will you add the RV9 to the list of aircraft?

 

[Vac]

Once the airplane starts moving, the computer (IOS device) switches to on-board sensors (the barometer, accelerometers and GPS in the phone itself), and updates all of the data real-time. Here is a takeoff and turn-back test, all flown on speed without any airspeed cues in the cockpit. Why on speed? It's optimum turn (maximum sustained turn rate), not best instantaneous turn--so the actual turn rate is slightly lower and turn radius is slightly larger; but it maintains a safe margin from stall and performance is certainly adequate. On speed glide is maximum endurance glide, not best range. That actually occurs at L/Dmax. For this stick monkey, the single "best performance blend, best stall margin" condition makes sense for a time-compressed maneuver close to the ground. The entire event will be over in less than a minute, and the idea of hitting multiple performance cues, while possible, isn't too likely when things have really gone south.

For folks without AOA, this means maintaining your normal Vref, while "honoring" stall warning (artificial or aerodynamic). We did extensive testing, and at Vref appropriate for flap setting, the airplane has a 1.5-2 degree stall margin in a 45 degree banked gliding turn. That's very close to the "not less than 5 knot" stall warning required by FAR 23. Now, unfortunately, there is no requirement to have stall warning in an RV or have anything calibrated in accordance with FAR 23. Most RV's provide little aerodynamic feed back at stalls less than 2 g's (i.e., buffet cues), so for airplanes without any form of AOA or stall warning, there is increased risk.

Now, let's take a look at what a decision aid looks like in flight. In this case I takeoff on speed and climb at L/Dmax to approximate Vy. When the computer tells me that I have a turn back solution for ambient conditions, I delay 3 seconds (to simulate startle, as NOTSO is doing in his experiment), and then apply flaps 40 (to adjust glide angle to equal real engine off glide angle) and then just fly the airplane on speed until touchdown:

Now let's look at using the computer if the engine fails at altitude. In this case, my objective is to get to "high key," a position over the runway from which I know I have sufficient energy to land. These tests consisted of flying around a suitable runway to random distances and altitudes; and then following the guidance after a simulated engine failure with Flaps 40 applied to replicate engine-off glide performance. Notice because this is altitude work, I adjusted the bank angle to something between 25-30 degrees (28 degrees in this test). That's so that the computer will drop me off at (about) a normal 180, power off base point. Note that as I get closer to the ground, the system continually computes different options to get to a touchdown point. I'm simply sticking to baseline: get to high key. Again, because I'm Vac and not the sharpest tool in the shed, instead of flying multiple conditions, I just fly the whole thing on speed and don't over-think it:

Recently, we integrated the computer (TLAR app) with Lockheed Prepar3D and the C172 flight model that RedBird simulators use. This allows us to teach and pilots to practice takeoff decision making in the simulator with real-time feed back from the phone/iPad just they way it works in flight. It's not perfect (due to the rate at which the simulator transmits information), but it's certainly usable. Here is a test using the Runway 5 scenario from Post 117. And yes, it would have been much smarter to just land on Runway 27 or a taxiway, but this was a flight test and the objective was to land on Runway 23 (the reciprocal of Runway 5). Something that you'll note in this demonstration is that if it's a maximum performance turn back, you won't land in the touchdown zone--you'll land well down the runway. The computer continually updates touchdown points real-time, so there should still be sufficient distance remaining to stop after touchdown. Notice I barely make the runway:

Now that we've discussed technique, let me piggy back on Paul's post: This is a "no other better alternative" maneuver, and I don't care how many lunar landings you have in your log book, you can not reliably do this without a computer to aid your decision matrix. 99.9% of the goodness of this approach is that you have made an assessment BEFORE you push the throttle up based on current conditions, because after that, all bets are off and it's a dynamic environment. Have folks done it sucessfully? You bet, and because it was successful, there isn't a statistic. But one statistic I like to quote from our study is that even if you hit something bolted to the ground and don't stall, the survival rate is still 75%. That "don't stall" part/fly the airplane all the way to the crash is the key to all of this, and AOA is a wonderful tool to know just how far from the stall you are when you fly--especially when you are sucking up the seat cushion trying not to die. In case I'm not perfectly clear: If there is ANY good option that requires minimum maneuvering ahead of the airplane, take it, and regardless of your game plan, do not let the airplane stall.

Fly safe,

Vac

PS, Dugaru, we have a bunch of airplanes modeled, but not the RV-9 at the moment. It takes a couple of days to update the code with a new aero model. We've got the -10 modeled and the airfoil data is likely "close enough" but I'll have to discuss it with the engineers since those are proprietary wing sections.

 

[Ironflight]

Sometimes it's the only airport around. Or all the airports have that same issue. This is what comes of allowing development right up to the runway, unfortunately. Airpots all around my neck of the woods are like that: Fullerton, Compton, Cable, Santa Monica, Burbank, Whiteman, and more. Could you base your airplane elsewhere? Sure, but an hour or two drive each way to get to the plane means you'd stop flying pretty quickly. Could I base my plane at SNA instead? Sure, if I wanted to leave it outside and pay $500 a month for the privilege. Or pay $3,000 a month for a T-hangar, if I could get one. Which I can't.

Phase One flight test areas are a different story. The risk is higher with a newly built aircraft, especially as it's often accompanied by a rusty PIC with little time in the airplane, so it makes sense to limit the operation for those first critical hours.

This lack of space around the runway isn't just a problem in the U.S. I recall holding short of the runway at Congonhas Airport in São Paulo, Brazil and realizing that a guy standing on his apartment balcony could probably jump right onto my wing from where he stood. In fact, that sort of thing is almost the rule rather than the exception. I've run into the same thing in Russia, Ecuador, China, and elsewhere.

--Ron

I get it Ron - I understand every one of your arguments and choices. And it remains that you are supplying the choices you made as a traders of risk. So how does you manage the risk if you choose to operate at an airport where wouldn’t no place to go (and yes, I have flown out of many places like Fullerton….)? Meticulous maintenance and testing to ensure that the engine will keep running, no compromise on anything that could stop it from running? That’s a very good start. We can argue that should - of course - be the case for every pilot and every airplane on every flight. And yet - engines still quit on take-off, and usually it can be traced to something toilet than an “act of god”.

Bottom line is that operating from “surrounded” airports is still a choice that pilots make. Choose wisely, as they say….

 

[Snowflake]

Vac, are you working on an Android, or web-based app, version?

 

[Fffflats]

View attachment 108555



View attachment 108557

At present, is this strictly flip “the 180” from 05 to 23? Or will it consider a right teardrop to 27? How about left teardrop to taxiway A?

 

[Fffflats]

One of things we learned in our research is that you must (I really mean MUST) use some sort of decision aid to be able to reliably do this under ambient conditions.

While I think having the aid is great, I disagree with this statement. You must have the aid if you are going to do it at the earliest possible moment such is available. If, however, you’re willing to cede not being able to do it at the earliest possible moment, then you can come up with rules of thumb. Schiff’s 360 test seems like a good place to start then work down in creating such ROTs. The glider 200 ft rope break is example of such ROT based on accepting you won’t have the earliest possible moment. Remember it is used in both gliders with 20:1 and those with 40:1. So, pilots can have something prior to the app being available to their type/model.

 

[Vac]

At present, is this strictly flip “the 180” from 05 to 23? Or will it consider a right teardrop to 27? How about left teardrop to taxiway A?

Working on it.

Like I said, folks have certainly done this with out an aid (just like we can drop bombs without a CCIP), and should it be practiced and discussed? Absolutely. I won't argue your statement--it's correct, but I'll just fall back that the real purpose of the aid is to have a plan in advance using the best resources available, since all of us carry one of these devices in our pocket.

Snowflake, not at the moment. Tough enough keeping up with Apple! That's already a full time job. Sorry about that.

Cheers,

Vac

 

[Fffflats]

For folks without AOA, this means maintaining your normal Vref, while "honoring" stall warning (artificial or aerodynamic). We did extensive testing, and at Vref appropriate for flap setting, the airplane has a 1.5-2 degree stall margin in a 45 degree banked gliding turn. That's very close to the "not less than 5 knot" stall warning required by FAR 23. Now, unfortunately, there is no requirement to have stall warning in an RV or have anything calibrated in accordance with FAR 23. Most RV's provide little aerodynamic feed back at stalls less than 2 g's (i.e., buffet cues), so for airplanes without any form of AOA or stall warning, there is increased risk.

A word of caution here, fortunately more-so for others than RVs, your flaps up condition may be considered an abnormal landing condition and therefore published Vref no flap may be less than 1.3 Vs. Pulling back to maintain Vref in a clean configuration in some planes can get you in such models. While there are others, I know for certain SR22, S22T, and Cessna 177RG are such models. Get the AOA and alleviate the concern. To truly replicate onspeed AOA, you’d use 1.2 Vref in the bank (assuming you’re using onspeed as proxy for minimum power required and optimum turn, which is good advice).

 

[Mikeyb]

I forget, are these demonstrations with idle power? Is the residual thrust significant?

 

[Norman CYYJ]

I forget, are these demonstrations with idle power? Is the residual thrust significant?

In my experience the residue thrust is significant. I know it isn't related but look at the amount of thrust you have at idle during a taxi versus a stopped prop.

 

[Notso]

To fly the turn as slow as possible, but not too slow. The goal is to achieve the minimum sink speed with a given bank angle.

Hmmm, I'll have to go try that and compare. But my sense from doing it was a slow turn is going to get you REALLY far away from the field.

Back to the AOA question - what specific AOA are you flying the turn so I can try to replicate it. Thanks.

 

[Notso]

While I am vocally not a proponent of a turnback (have lost too many friends who have tried it - some of them VERY experienced pilots), I wish people would stop talking about “Straight” ahead! I prefer to simple use “land ahead” - which helps you think of anywhere within 90 degrees of runway heading, left or right. I totally agree that landing othat n the airport property (generally level and clear) is better than going in to houses, and a turn of 90 will greatly increase your options. The runway? Often that’s a pipe dream - and not required to survive. I know of actual friend’s accidents that wouldn’t have been fatal of they had taken that option.

And if there is truly no option for an engine failure at your airport….you have to ask why you;re using that airport! That is a decision that you have made that limits your options. It’s why, as a DAR, there are airports where we are not allowed to let folks do Phase 1.

Totally agree... and we had that exact discussion among our group that you are not locked into a "Straight ahead" engine out landing and that 90 L or R could open up many possibilities. Its all obviously very situation and location dependent. In our case at KVGT, the airport is surrounded completely by dense houses. So in our case, a 90 deg turn really does't change the equation.

But yeah, I 1000% agree that the T/O "RUNWAY" is not always the primary goal. If you can get back to within the airport perimeter, that potentially opens up LOTS of options. If you guys go back and look at my videos, there are several good options that come in view short of the actual runway that would make very viable landing surfaces. There is a long parallel dirt road on the near side of the hangars as well as an asphalt taxi way just short. So don't just tunnel vision on the runway itself.

Back To the "straight ahead" thing..... I think unfortunately - that has become the word that young CFIs use to teach new students and they never explain the nuance of what that really means. And don't get me started on "young CFIs" - that's a whole 'nother animal that will get me animated.

 

[Notso]

I forget, are these demonstrations with idle power? Is the residual thrust significant?

Yes, I pulled the throttle to full idle at the moment of "engine fail" and left it there until I either touched down or elected to GO AROUND if I felt I could not safely make the runway.

Also, I did NOT pull the prop AFT to full coarse - as that would have in theory made the glide ratio slightly better in most cases. I wanted to keep the tests to worst case in the event the oil system "s**t itself and there was no oil pressure left to get to that coarse setting.

And FTR - I have a 3 blade WW with the idle stops set correctly at 2550 static per the manual.

 

[Notso]

In my experience the residue thrust is significant. I know it isn't related but look at the amount of thrust you have at idle during a taxi versus a stopped prop.

Idle thrust is certainly a factor - I don't know how "significant" it is. And I'm not willing to actually turn off my engine inflight to attempt to quantify it. LOL

My understanding is a windmilling prop at full fine is actually quite a bit MORE drag that a stopped prop or even one windmilling at full coarse if you had the oil pressure available to "pull the prop" in the event of a real engine failure. So in some ways, my tests might have actually had more drag than whatever idle thrust it was giving me. Ofc, it depends on where you have your idle set to. Mine is about 650 on the ground but if you have yours more like 800, yes that would be a fair amount of difference.

As an example of windmilling prop drag - In one phase of my military career, we would routinely practice SFO approaches in a single engine turbine prop. To simulate the correct drag of a feathered prop vs one that's windmilling - we would actually bump UP the power to about 10% above idle. Because at idle and windmilling - the prop drag was so significant that it would kill your glide ratio and make your practice invalid. I realize that's not apples to apples ofc - but it gives an idea of the windmilling prop drag that many don't consider.

 

[Vac]

A word of caution here, fortunately more-so for others than RVs, your flaps up condition may be considered an abnormal landing condition and therefore published Vref no flap may be less than 1.3 Vs. Pulling back to maintain Vref in a clean configuration in some planes can get you in such models. While there are others, I know for certain SR22, S22T, and Cessna 177RG are such models. Get the AOA and alleviate the concern. To truly replicate onspeed AOA, you’d use 1.2 Vref in the bank (assuming you’re using onspeed as proxy for minimum power required and optimum turn, which is good advice).

Flats, absolutely! That’s why I said “Vref appropriate for flap condition” in the description. Vs for flap setting x 1.2-1.3 would have been a better answer , no excuse.

 

[Mikeyb]

Idle thrust is certainly a factor - I don't know how "significant" it is. And I'm not willing to actually turn off my engine inflight to attempt to quantify it. LOL

My understanding is a windmilling prop at full fine is actually quite a bit MORE drag that a stopped prop or even one windmilling at full coarse if you had the oil pressure available to "pull the prop" in the event of a real engine failure. So in some ways, my tests might have actually had more drag than whatever idle thrust it was giving me. Ofc, it depends on where you have your idle set to. Mine is about 650 on the ground but if you have yours more like 800, yes that would be a fair amount of difference.

As an example of windmilling prop drag - In one phase of my military career, we would routinely practice SFO approaches in a single engine turbine prop. To simulate the correct drag of a feathered prop vs one that's windmilling - we would actually bump UP the power to about 10% above idle. Because at idle and windmilling - the prop drag was so significant that it would kill your glide ratio and make your practice invalid. I realize that's not apples to apples ofc - but it gives an idea of the windmilling prop drag that many don't consider.

In the case of my CS prop the on-speed rate of decent is 700 fpm if I have oil pressure and can get it to course pitch but at fine pitch it’s 1100 fpm. Does that imply I should stop the prop?

Most of the new RV builders I know are older and have less current flying experience. It all gets so daunting.

 

[rocketman1988]

“…Back To the "straight ahead" thing..... I think unfortunately - that has become the word that young CFIs use to teach new students and they never explain the nuance of what that really means. And don't get me started on "young CFIs" - that's a whole 'nother animal that will get me animated...”

While I agree that a lot of young cfis do not explain “straight ahead” adequately, I have recently seen a few preaching the “impossible turn” instead…which isn’t any better and could end up much worse. Blame it on the recent articles and media, I guess.

You can get spooled up about young instructors but the fact is, you were a young instructor at one time, too.

That is why it is really important to be a mentor to these young cfis…if you aren’t mentoring then you probably shouldn’t be complaining…

 

[Fffflats]

Hmmm, I'll have to go try that and compare. But my sense from doing it was a slow turn is going to get you REALLY far away from the field.

Back to the AOA question - what specific AOA are you flying the turn so I can try to replicate it. Thanks.

Slow turn doesn’t mean shallow turn. You’re balancing rate v radius though ultimately your goal is most degrees of turn for least altitude lost. Worry about distance per altitude in the straights. Technically minimum power required AOA at forty-five AOB is optimum though as Vac suggests, using onspeed AOA in lieu of such typically is close enough while giving margin to stall and, what I hadn’t previously considered, making for the need to only think of one value. As for the turn, a little steeper is actually a better error than shallower but we’re quibbling at this point, and you really want AOA indication to make such.

 

[Dugaru]

PS, Dugaru, we have a bunch of airplanes modeled, but not the RV-9 at the moment. It takes a couple of days to update the code with a new aero model. We've got the -10 modeled and the airfoil data is likely "close enough" but I'll have to discuss it with the engineers since those are proprietary wing sections.

And of course it’s just like me to see an amazing free app, and immediately demand more free labor from you. I’m truly grateful for what you’ve done so far, this is really quite something.

 

[Derek.plough]

Is the return to land calculation feature available on the free version or only with the “expert” subscription plan?

 

[ronrapp]

In the case of my CS prop the on-speed rate of decent is 700 fpm if I have oil pressure and can get it to course pitch but at fine pitch it’s 1100 fpm. Does that imply I should stop the prop?

As with all things RV, the answer is: it depends. If you have an engine failure at a high enough altitude to be able to monkey with that, then that's one thing. But if the engine fails at 500' AGL, I honestly wouldn't mess with it. And I've done a lot of turbacks in many different aircraft types, including with the engine actually shut down.

It also depends what form the failure takes. Partial failure? Total loss with no oil pressure? And do you have an aerobatic CS prop or a standard one? Because the acro propeller will go to high pitch/low RPM without oil pressure. And where are you? In the midwest were there are decent landing options? Or in a highly urbanized area where your options are much more limited?

The time to think all this through is before takeoff, but I'm not sure how many of us do that. Consider the wind, other runways available or in use, the weight and CG location, your own currency with the airplane and airport, your fatigue level, and so on. It's worth looking at the entire airport property and seeing where you could land without making the runway. Taxiways, grass, ramps.

A lot of variables. Anyway, sorry -- I went way off topic from your question. Stopping the prop will generally increase your glide performance, but it takes time and attention to get it stopped that you might not have available.

--Ron

 

[rv8ch]

It's an IOS app (sorry android people ) called TLAR, military slang for "that looks about right." It's the expert version and you can access it at TLARPilot.com.

Hi Vac, looks great - but I can't download it due to some kind of Apple App Store region locking - any plans to allow non-US downloads?

 

[glider_rider]

Hmmm, I'll have to go try that and compare. But my sense from doing it was a slow turn is going to get you REALLY far away from the field.

Back to the AOA question - what specific AOA are you flying the turn so I can try to replicate it. Thanks.

Dynon Skyview

 

[Capt]

With any of the machines I drive including my 4 these days (as I’m now far more wise than when I started driving planes 46 years ago) I simply don’t fly into places that I can’t land straight ahead after T/off, it’s called risk mitigation

 

[jrs14855]

Is the return to land calculation feature available on the free version or only with the “expert” subscription plan?

I get it Ron - I understand every one of your arguments and choices. And it remains that you are supplying the choices you made as a traders of risk. So how does you manage the risk if you choose to operate at an airport where wouldn’t no place to go (and yes, I have flown out of many places like Fullerton….)? Meticulous maintenance and testing to ensure that the engine will keep running, no compromise on anything that could stop it from running? That’s a very good start. We can argue that should - of course - be the case for every pilot and every airplane on every flight. And yet - engines still quit on take-off, and usually it can be traced to something toilet than an “act of god”.

Bottom line is that operating from “surrounded” airports is still a choice that pilots make. Choose wisely, as they say….

As with all things RV, the answer is: it depends. If you have an engine failure at a high enough altitude to be able to monkey with that, then that's one thing. But if the engine fails at 500' AGL, I honestly wouldn't mess with it. And I've done a lot of turbacks in many different aircraft types, including with the engine actually shut down.

It also depends what form the failure takes. Partial failure? Total loss with no oil pressure? And do you have an aerobatic CS prop or a standard one? Because the acro propeller will go to high pitch/low RPM without oil pressure. And where are you? In the midwest were there are decent landing options? Or in a highly urbanized area where your options are much more limited?

The time to think all this through is before takeoff, but I'm not sure how many of us do that. Consider the wind, other runways available or in use, the weight and CG location, your own currency with the airplane and airport, your fatigue level, and so on. It's worth looking at the entire airport property and seeing where you could land without making the runway. Taxiways, grass, ramps.

A lot of variables. Anyway, sorry -- I went way off topic from your question. Stopping the prop will generally increase your glide performance, but it takes time and attention to get it stopped that you might not have available.

--Ron

Ron-
Thanks for your usual concise information. I am stuck with a less than ideal airport situation. With the exception of magneto issues I have never had a total failure of a Lycoming. I do my own engine work but engine failures can be largely eliminated by staying far away from "Shade Tree Aviation".

 

[Gino230]

While I am vocally not a proponent of a turnback (have lost too many friends who have tried it - some of them VERY experienced pilots), I wish people would stop talking about “Straight” ahead! I prefer to simple use “land ahead” - which helps you think of anywhere within 90 degrees of runway heading, left or right. I totally agree that landing on the airport property (generally level and clear) is better than going in to houses, and a turn of 90 will greatly increase your options. The runway? Often that’s a pipe dream - and not required to survive. I know of actual friend’s accidents that wouldn’t have been fatal of they had taken that option.

And if there is truly no option for an engine failure at your airport….you have to ask why you;re using that airport! That is a decision that you have made that limits your options. It’s why, as a DAR, there are airports where we are not allowed to let folks do Phase 1.

For me, it was the choice of a crummy airport, or basically don't do any GA flying. We make all kinds of risk assessments. I choose to accept the risk of flying an EAB that I didn't build out of a densely populated area. Then I go and do aerobatics in it to boot.

I try to mitigate that risk with training, practice, fastidious maintenance, and not taking any extra risks with fuel levels and quality (mogas for example) among other things.

But what I like most about this thread (and VAF in general) is pilots demonstrating what these aircraft are capable of with proper training and practice- Pilots going out and practicing for stuff that might save their lives one day, even if they don't make it back to the departure runway, maybe they make it to a road, levee, or open spot they may not have otherwise tried for. Grateful to all of you for sharing your findings, even if it's not appropriate for all of us to attempt right off the bat.

My 2c is that pilots who are out there practicing and finding limits regularly are going to end up with a better chance of having a good outcome in the face of a crappy situation- because they are probably more proficient than the guy who practices nothing and just jumps in and heads to Oshkosh once a year, like Paul says. Maybe the turn back isn't the best move, but practicing it will make you a better pilot with a higher understanding of you and your aircrafts capabilities. Rock on!

 

[Gino230]

That's a very powerful demonstration of how quickly we can get in trouble. And the conditions for this are very common, at least in my experience. Rarely does it happen when you do everything the same way, and are alone in the pattern. It's when you are going to a fly-in, or the pattern is very busy, or a slow aircraft cuts you off, or ATC asks for a 360 for spacing, or some other non-standard event. You stop thinking about flying the aircraft for just a moment, and then you're a smoking heap in a cornfield.

Thanks for producing and sharing these videos, Vac!

This video was the motivation for me to take my RV8 out and practice making some tight pattern like turns at slow speed (at 7000' of course). Even applying up to 2G at 80MPH doesn't result in a departure like that with the ball centered, anyway. It made me alot more comfortable in the pattern.

The builders truly have the advantage here, if they did all of the test cards and flew the aircraft in the various conditions. Since I didn't build mine and it came with no POH to speak of, I tried alot of things. Not quite my own phase 1 but close!

 

[Notso]

You can get spooled up about young instructors but the fact is, you were a young instructor at one time, too.

That is why it is really important to be a mentor to these young cfis…if you aren’t mentoring then you probably shouldn’t be complaining…

100% agree. But I was not getting spun up as an "old head" CFI. I was getting spun up about young CFIs because I very recently went through a Part 141 CFI course because I had GI Bill $$ to burn. I figured rather than going the easy way and just getting a Mil instructor to FAA CFI equivalency ticket conversion - I'd go through the full CFI course to learn all the new ways that the FAA wants students to be taught, make sure I wasn't teaching anything wrong from the "old days", actually learn the ACS, and so on.

My experience was the school was nothing more than a "puppy mill". Outside of the ground school portion, I got absolute minimum instruction, very little plan of what we were doing that day, several were on their iphones during ground ops and in flight. We'd land, park, tie down, walk in - and the debrief was usually - "you did great, I'll see you next time" just as they are finding their next student to walk back out to the airplane. The majority of any conversations were them talking about how they are waiting for their call to a Part 135 gig or similar.

I'm sorry, I was just very unimpressed. And I've heard this from several people I know who are going through similar schools. Sure, they can quote chapter and verse of the PHAK and the FARs - but their flying skills are meh and their overall SA is average.

To your point about mentoring them.... I honestly tried with a few, gently given I've been a IP longer than most have been alive. Most didn't want to hear it or didn't have time. So..... [shrug]

 

[Notso]

Slow turn doesn’t mean shallow turn. You’re balancing rate v radius though ultimately your goal is most degrees of turn for least altitude lost. Worry about distance per altitude in the straights. Technically minimum power required AOA at forty-five AOB is optimum though as Vac suggests, using onspeed AOA in lieu of such typically is close enough while giving margin to stall and, what I hadn’t previously considered, making for the need to only think of one value. As for the turn, a little steeper is actually a better error than shallower but we’re quibbling at this point, and you really want AOA indication to make such.

Dude, Agree steeper is better as long as you're not stalling. But I'm not sure I agree that staring at an AOA gauge around that turn is the appropriate use of your attention. I'm pretty sure that if I lost my engine on takeoff and elected to make that "impossible" turn back to the airport - my eyes are going to be out 90% of the time, while making a steep bank turn to the runway with an occasional glance in to check airspeed, AOA, or whatever.

 

[Notso]

In the case of my CS prop the on-speed rate of decent is 700 fpm if I have oil pressure and can get it to course pitch but at fine pitch it’s 1100 fpm. Does that imply I should stop the prop?

Most of the new RV builders I know are older and have less current flying experience. It all gets so daunting.

@ronrapp said it better than I could. As always, it depends. But I do agree that if you lose your engine at low altitude, flying the plane to the runways/airport/desired landing spot is FAR FAR more critical that attempts to stop the prop. If you have oil pressure, maybe just pulling the prop lever might be the small edge to get you over the fence. But I would concentrate on flying the airplane first!!

 

[Notso]

This video was the motivation for me to take my RV8 out and practice making some tight pattern like turns at slow speed (at 7000' of course). Even applying up to 2G at 80MPH doesn't result in a departure like that with the ball centered, anyway. It made me alot more comfortable in the pattern.

The builders truly have the advantage here, if they did all of the test cards and flew the aircraft in the various conditions. Since I didn't build mine and it came with no POH to speak of, I tried alot of things. Not quite my own phase 1 but close!

LOL, then you definitely don't want to see the videos of my "alternate" turn back method. I would get crucified here.... It worked, but I don't recommend it for the average GA pilot. And I include myself in that category.

 

[Vac]

At the risk of oversimplifying things here, in the event of an actual loss of power and you can't restore power: Don't bother trying to stop the prop (if it's controllable) below 3000 feet AGL. There is an excellent CAFE study explain that explains why. If you have control of the prop, rip it back to low RPM to reduce drag if you lose power. If it responds, great, if it doesn't, is what it is. NOTSO's technique of assuming worst case is probably best for practice. If it's a fixed pitch prop, it will take care of itself, no brain bytes required. Simple decision matrix .

v/r,

Vac

 

[Notso]

At the risk of oversimplifying things here, in the event of an actual loss of power and you can't restore power: Don't bother trying to stop the prop (if it's controllable) below 3000 feet AGL. There is an excellent CAFE study explain that explains why. If you have control of the prop, rip it back to low RPM to reduce drag if you lose power. If it responds, great, if it doesn't, is what it is. If it's a fixed pitch prop, it will take care of itself, no brain bytes required. Simple decision matrix .

v/r,

Vac

Yep, zactly!