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Impossible Turn (RV4)

Knowing HOW to do a turn back is probably just as important as knowing WHEN to do a turn back certainly not greater given in many if not most engine outs on takeoff straight ahead is probably preferred. BWTHDIK
 
Turn Back

I try to read all the pertinent accident reports but I don't keep records. It seems like every few months there is an attempt by someone in a A36 Bonanza for example who tries to turn back from 100' or less. Also an "alternative engine" Lancair 4 a few years back same scenario. Obviously no preflight planning for "what if" in either case.
 
Knowing HOW to do a turn back is probably just as important as knowing WHEN to do a turn back certainly not greater given in many if not most engine outs on takeoff straight ahead is probably preferred. BWTHDIK

Knowing how and WHEN to use a turn back is very important. Using perfect technique won't help you if the airplane is simply incapable of doing what you're asking of it. Do we have the fortitude to be part way through a turn around and realize we've made the wrong decision and choose a off-field landing instead?

Maybe.

I have a friend with an SR22 who recently departed the Tuscon area for Socal (plan A). His IO550 suffered a catastrophic failure. Plan B: he headed toward a airfield within glide distance, but ATC told him there was a lot of glider activity in the area. Plan C was to pull the airframe parachute handle. It did not deploy. Tried it again, harder. No luck. So he proceeded to Plan D and landed on a dirt road. Of course he had the benefit of altitude, and therefore, time.

In multi-engine aircraft, a thorough takeoff briefing is always done prior to departure. Single engine pilots do not typically perform any kind of takeoff briefing -- I've often thought that might be a missed opportunity to mentally prepare for and rehearse what a low altitude emergency might look like and pre-determine a course of action based on the field length, obstacles, aircraft weight/performance, surrounding terrain, wind, traffic, and so on.

Gulfstream published a presentation a while back that iterated their viewpoint that there is no such thing as a "standard" briefing. The conditions of each takeoff are unique and have to be thoughtfully considered.

About 8 years ago I wrote an article on this topic, advocating takeoff briefings for single engine aircraft:

https://www.rapp.org/archives/2014/08/takeoff-briefings/

--Ron
 
a complete takeoff briefing

While this is theoretically true it does not always happen in the corporate world.
The young man who was in the right seat in the King Air 350 that crashed into the hangar at Dallas Addison was someone I had worked with and flown with.
This was a new operation, it may have been his first time with that Captain .No weight and balance, no checklists, no takeoff briefing, power lever friction not adjusted properly. Power rolled back to idle on one engine after rotation, pilot pushed the wrong rudder pedal, the airplane rolled inverted and crashed.
Auto feather either not working or not used. A "highly experienced Captain".
I of course will never know but I sincerely believe the copilot was told "sit on your hands and don't touch anything", just as was common in the airline DC3 era.
A pre takeoff briefing for a solo pilot in a single:
Below 100' in the event of an engine failure or loss of power I will land straight ahead. If a loss of power I will close the throttle. If it appears I will run off the end of the runway I will turn off the master switch, magnetos and fuel if time permits.
Above 100' I will consider a 90 degree turn if terrain or obstacles make that the best choice.
Above 300' I will consider a turn back to the runway if terrain or obstacles make that the best choice. All based on a relatively short runway.
FLY THE AIRPLANE. In my EAB I can turn off the mags, battery switch and fuel without diverting my focus from outside the airplane. Can You???
 
About 8 years ago I wrote an article on this topic, advocating takeoff briefings for single engine aircraft:

https://www.rapp.org/archives/2014/08/takeoff-briefings/

--Ron

There has been at least one EAA safety webinar that recommended performing a pre-takeoff briefing, specifically for the engine out scenario at takeoff, even for a local flight. I don't know any basic flight training that teaches this, maybe except for the commercial/corporate/airline world
 
There has been at least one EAA safety webinar that recommended performing a pre-takeoff briefing, specifically for the engine out scenario at takeoff, even for a local flight. I don't know any basic flight training that teaches this, maybe except for the commercial/corporate/airline world
Starting to appreciate my training a bit more. It's pretty settled science that getting important stuff into your "working memory" can greatly increase performance.
 
There has been at least one EAA safety webinar that recommended performing a pre-takeoff briefing, specifically for the engine out scenario at takeoff, even for a local flight. I don't know any basic flight training that teaches this, maybe except for the commercial/corporate/airline world

I can tell you that at the soaring school where I got my glider rating, failure to verbalize the pre-flight briefing before signaling the tow plane to go ensured that you’d have a 200’ rope brake, courtesy of the instructor in the back seat. I try to always verbalize my take-off emergency plan as I take the runway, in whatever I am flying. It just focuses me better.

Paul
 
I can tell you that at the soaring school where I got my glider rating, failure to verbalize the pre-flight briefing before signaling the tow plane to go ensured that you’d have a 200’ rope brake, courtesy of the instructor in the back seat.

Likewise at the FBO where I earned my commercial glider add-on. Seems to be pretty standard. I wonder why it never took hold with single engine aircraft.

--Ron
 
Flight Test Data RV-7

Hello All,

Did some flight testing on this topic and here is what I found:

For RV-7, TU, Empty Weight 1286, Solo Configuration (max fuel), IO 390, MT 3 blade composite controllable at course pitch down to 80 MPH

Test runs conducted at best glide configuration engine out with mixture at fuel cutoff. Dive initiated to build speed to achieve a climb attitude at 120 MPH (my normal climb speed). Then a three second delayed response was held at climb attitude as airspeed bled. An unloaded roll to 45-50 degrees, then O/S AoA held at that AoB (1.7 G) for 270 degrees. An unloaded reversal to 45-50 degrees to the other side and another 90 degrees at O/S AoA.

This routine was repeated a few times flaps up, then done a few more times flaps at 10 degrees.

Altitude loss average 700' flaps up and 650' flaps 10 degrees.

Distance made good back to runway is approximately 900'

My distance travelled to reach 650' AGL that day was 7,900'


Takeaway:

Given a 7,000' runway 650' AGL is required for me to make it to the opposite threshold. I need to do some more math to figure out how the roughly 7:1 climb relates to the 11:1 glide to figure out the turn around altitude for runways shorter than 7000'

Of course there may be cleared field available, roads, etc. This exercise was to crunch numbers in actual no power conditions to see what is needed for the ideal recovery.
 
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Thanks for posting your test result. 1050ft AGL is at pattern altitude so it's not low at all. Do you recall the density altitude for your test? I wonder if it has a role in the turn back altitude
 
Density Altitude

It was a mixed bag 6500-3500' DA for 5000-2000' of Indicated Alt.

Numbers got slightly better at lower altitude, much better with the added flap.

My reported numbers are averages which should provide me some margin in the true low altitude scenarios and hopefully minimal reliability for my home field of Truckee.
 
I sincerely hope all of you who are conducting this testing are doing it at a safe altitude (both for your safety and because that's what the AC requires). Let's not applaud AOPA for conducting these tests in this fashion as any mistake that low would have been fatal. 45 degrees of bank just above a stall at less than 300' AGL (or even 1000' AGL) is a death wish. I'll admit that I haven't practiced this maneuver and I probably should take some time to do it at a safe altitude simply to know my airplane's limits.

If I haven't started my downwind turn I'm not even considering a turn back towards the airport. Preventing a stall/spin is my main concern. At least you have a chance in a controlled off-airport landing. I make a verbal takeoff briefing expecting an engine failure followed by nose down and blue mark (DMMS) on the ASI.
 
Vince, sound methodology. Thanks for sharing results.

Low altitude maneuvering is an energy/AOA management problem. There is an optimum AOA for approach and landing that is coincident with maximum sustained turn rate. In the military, we called this an ONSPEED condition. If an aircraft is ONSPEED, energy “burn” and turn performance are optimum. It’s also usable trade-off between maximum duration and range glide (max endurance glide occurs ONSPEED flaps up, and as flaps are deployed, L/Dmax and ONSPEED marry up), so it’s a simple single reference to fly to the crash if there is a loss of power:

https://youtu.be/LT6OSNblXpc

Notes, warnings and cautions: I’m not advocating any specific course of action in the event of engine failure except to maintain aircraft control—this is a discussion forum, not a flight training institution. The video is a demonstration of using a calibrated AOA/energy cue as a primary reference, which is something we did in the military. Since I’m flying AOA as my primary reference, bank angle is “whatever it takes.” I wouldn’t attempt this without accurate, easy to use AOA cuing. The steady tone tells me the airplane is in an ONSPEED condition. I adjust AOA based on the tone. This is a test, so there is no startle factor. I allow three seconds after simulated power loss prior to maneuvering. The airplane has a fixed pitch propeller, so there is some residual thrust at idle. Performance would also be different with a controllable pitch propeller, depending on RPM. Field elevation is 250’ MSL. In this test, the throttle is pulled to IDLE at 250’ AGL at L/Dmax AOA during initial climb segment. Flaps 20 is selected for the turn back (best compromise for lift benefit vs drag with my 2-position manual flaps at low altitude). See post 31 for links to additional technical resources if you are joining the discussion late.

Fly safe,

Vac
FlyONSPEED.org
 
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Vince, sound methodology. Thanks for sharing results.

Low altitude maneuvering is an energy/AOA management problem. There is an optimum AOA for approach and landing that is coincident with maximum sustained turn rate. In the military, we called this an ONSPEED condition. If an aircraft is ONSPEED, energy “burn” and turn performance are optimum. It’s also usable trade-off between maximum duration and range glide (max endurance glide occurs ONSPEED flaps up, and as flaps are deployed, L/Dmax and ONSPEED marry up), so it’s a simple single reference to fly to the crash if there is a loss of power:

https://youtu.be/LT6OSNblXpc

Notes, warnings and cautions: I’m not advocating any specific course of action in the event of engine failure except to maintain aircraft control—this is a discussion forum, not a flight training institution. The video is a demonstration of using a calibrated AOA/energy cue as a primary reference, which is something we did in the military. Since I’m flying AOA as my primary reference, bank angle is “whatever it takes.” I wouldn’t attempt this without accurate, easy to use AOA cuing. The steady tone tells me the airplane is in an ONSPEED condition. I adjust AOA based on the tone. This is a test, so there is no startle factor. I allow three seconds after simulated power loss prior to maneuvering. The airplane has a fixed pitch propeller, so there is some residual thrust at idle. Performance would also be different with a controllable pitch propeller, depending on RPM. Field elevation is 250’ MSL. In this test, the throttle is pulled to IDLE at 250’ AGL at L/Dmax AOA during initial climb segment. Flaps 20 is selected for the turn back (best compromise for lift benefit vs drag with my 2-position manual flaps at low altitude). See post 31 for links to additional technical resources if you are joining the discussion late.

Fly safe,

Vac
FlyONSPEED.org

What you're doing with ONSPEED is awesome and I believe affordable AOA management solutions will make GA significantly safer and prevent many fatalities. However, advocating that doing the turnback test at 250' AGL is acceptable, even with an AOA indicator, will likely cause someone to kill themselves while trying it. Since this subsection of VAF is dedicated to safety, I want to make it clear that this practice is UNSAFE and should never be tried without sufficient altitude to recover from an inadvertent stall/spin.
 
Misperception of flying AoA

As a sea going Marine I cut my teeth on AoA vs Airspeeds for all flight regimes except maneuvering speed and runway numbers for obvious reasons. So when I went GA I always wondered why floating airspeed references were vogue for things like cruise, stall, climb and endurance.

But there certainly is a strong desire to focus on airspeed in GA, I get that.

What Vac is trying valiantly to do is to get a paradigm shift toward AoA.

A spin entry at anything below spin recovery altitude plus change is to be avoided at all costs. We can't do that with airspeed but we can do that with AoA and proper feet control. Spin entry requires excessive AoA and asymmetric loading. If AoA and coordination are managed a spin is impossible, I say again impossible. I would even go as far as to say that if AoA OR coordination are managed a spin is avoided. But safer to keep both under control.

So a gentle 20 deg AoB in the pattern at O/S AoA presents the same aerodynamic risk as 45 deg AoB at O/S AoA. In fact the 45 deg bank at O/S AoA preserves more kinetic energy so one could argue it is even safer.

Power out: There are reasonable bugaboos out there for pulling the fuel out of the engine while airborne. Thought must be given to thermodynamic changes, but that's manageable inflight and doesn't need to be any more extreme than an ordinary shutdown. I personally don't think using the full range of the mixture knob is any more dangerous than using a partial range but that is just me. Everybody who agrees to fully test their experimental aircraft and determine their true operational performance envelopes (Phase 1) must wrestle with the decision to go there. But I do believe we each must know our real glide numbers straight ahead and in turns. Imagine if our trusty 152 glide numbers were given to us by the factory as a best guess.

My point is that we shouldn't confuse a risk of spin entry with managed AoA.
 
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Hi Cole,

Your caution and thoughtfulness are spot on. I apologize if "I’m not advocating any specific course of action in the event of engine failure except to maintain aircraft control—this is a discussion forum, not a flight training institution..." wasn't clear.

We are a group of flight test professionals that have a volunteer project trying to demonstrate what is in the art of the doable with the proper equipment and training. We operate instrumented aircraft under controlled conditions. We follow standard practice and approach each objective in steps. The video does not depict the several weeks of work prior, just a specific test conducted for the purpose of test. The military has come up with some good technology and techniques that may benefit GA. Our only objective is to develop the resources (hardware, software and training) and demonstrate the technology so that folks in GA have an opportunity to consider what has worked in another aviation community to reduce loss of control risk. After four combat tours, lots of test work and 42 years of flying, I hope that I'm applying reasonable operational risk management principles in the conduct of test operations. I can't improve on the description in the prior post (#65) regarding risk assessment. My type certificate says "experimental," and I take the "experimental test pilot" part very seriously every time I fly. I hope that sharing the results of our work isn't perceived as dangerous, but rather contributes positively to the safety discourse.

Give me a call any time you'd like if you want to discuss any of our work or how we conduct test--my contact info is on our web site (FlyONSPEED.org). If you are at Oshkosh, stop by and enjoy a beverage with us!

v/r,

Vac
 
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As a sea going Marine I cut my teeth on AoA vs Airspeeds for all flight regimes except maneuvering speed and runway numbers for obvious reasons. So when I went GA I always wondered why floating airspeed references were vogue for things like cruise, stall, climb and endurance.

But there certainly is a strong desire to focus on airspeed in GA, I get that.

What Vac is trying valiantly to do is to get a paradigm shift toward AoA.

A spin entry at anything below spin recovery altitude plus change is to be avoided at all costs. We can't do that with airspeed but we can do that with AoA and proper feet control. Spin entry requires excessive AoA and asymmetric loading. If AoA and coordination are managed a spin is impossible, I say again impossible. I would even go as far as to say that if AoA OR coordination are managed a spin is avoided. But safer to keep both under control.

So a gentle 20 deg AoB in the pattern at O/S AoA presents the same aerodynamic risk as 45 deg AoB at O/S AoA. In fact the 45 deg bank at O/S AoA preserves more kinetic energy so one could argue it is even safer.

Power out: There are reasonable bugaboos out there for pulling the fuel out of the engine while airborne. Thought must be given to thermodynamic changes, but that's manageable inflight and doesn't need to be any more extreme than an ordinary shutdown. I personally don't think using the full range of the mixture knob is any more dangerous than using a partial range but that is just me. Everybody who agrees to fully test their experimental aircraft and determine their true operational performance envelopes (Phase 1) must wrestle with the decision to go there. But I do believe we each must know our real glide numbers straight ahead and in turns. Imagine if our trusty 152 glide numbers were given to us by the factory as a best guess.

My point is that we shouldn't confuse a risk of spin entry with managed AoA.

The Onspeed device works for our EAB, Vans, but for most of the training fleet comprised of older 172 and Cherokee, the OnSpeed device and precise AoA measurement aren't available. So the GA fleet relies on the power settings and reference speeds. I think this method has worked well for the GA, especially for teaching new pilots.
 
Hi Vac,

I whole-heartedly believe in the work ya'll at ONSPEED are doing and will definitely be considering installing it on my own airplane.

In your particular case, your mission and background probably do support this style of testing. Plus you know the risks involved with a mistake or equipment failure. The rest of us, on the other hand, have no business risking our lives with unnecessary low altitude maneuvers, especially without an AoA management system. My hope is that those on this forum who have done or are thinking of attempting this at low altitude will reconsider.

No Oshkosh for me this year but I will definitely be following your progress!
 
Airspeed effective in training?

I totally understand that AoA employment is far easier in EAB.

Supply-Demand.....Chicken-Egg......other platitudes about how we change. Change is hard but it starts somewhere.

I don't agree that aerodynamic control of our wings has been well served by years of airspeed references in our light trainers. GA owns the lionshare of aviation mishaps even when normalized by flights or hours flown. And loss of control sits atop the list of causal factors.

Look at a community that actively manages AoA such as the F-18 world: Even though high AoA flight is routine, loss of control isn't a high causal factor.

I reluctantly admit having worked in the Aviation Safety world more than I would have thought prudent. From that perspective I can say with confidence that a lot of people have spent a lot of time trying to figure out how to knock the 'Loss of Control Inflight' statistic down. Switching to AoA for aerodynamic performance seems a no-brainer. Retrofits aren't taboo, look at shoulder straps. Institutional stubbornness?
 

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Vince, sound methodology. Thanks for sharing results.

Low altitude maneuvering is an energy/AOA management problem. There is an optimum AOA for approach and landing that is coincident with maximum sustained turn rate. In the military, we called this an ONSPEED condition. If an aircraft is ONSPEED, energy “burn” and turn performance are optimum. It’s also usable trade-off between maximum duration and range glide (max endurance glide occurs ONSPEED flaps up, and as flaps are deployed, L/Dmax and ONSPEED marry up), so it’s a simple single reference to fly to the crash if there is a loss of power:

https://youtu.be/LT6OSNblXpc

Notes, warnings and cautions: I’m not advocating any specific course of action in the event of engine failure except to maintain aircraft control—this is a discussion forum, not a flight training institution. The video is a demonstration of using a calibrated AOA/energy cue as a primary reference, which is something we did in the military. Since I’m flying AOA as my primary reference, bank angle is “whatever it takes.” I wouldn’t attempt this without accurate, easy to use AOA cuing. The steady tone tells me the airplane is in an ONSPEED condition. I adjust AOA based on the tone. This is a test, so there is no startle factor. I allow three seconds after simulated power loss prior to maneuvering. The airplane has a fixed pitch propeller, so there is some residual thrust at idle. Performance would also be different with a controllable pitch propeller, depending on RPM. Field elevation is 250’ MSL. In this test, the throttle is pulled to IDLE at 250’ AGL at L/Dmax AOA during initial climb segment. Flaps 20 is selected for the turn back (best compromise for lift benefit vs drag with my 2-position manual flaps at low altitude). See post 31 for links to additional technical resources if you are joining the discussion late.

Fly safe,

Vac
FlyONSPEED.org

Are y'all gonna be a AirVenture?
 
Hi Stan,

Yes we are. The AOA forum is on Friday 30 Jul 0830 Workshop Classroom A. We are also doing a HUD forum on Wed 28 Jul at 1300 in the Homebuilder's Hangar. We'll be at the beer tasting and Monday night social as well. Contact info is on the front page of our web site if you want to run us down.

Cheers,

Vac
 
Theoretical turn back numbers based on actual findings

I think I've got this right, somebody chime in if you see a logical error.

In previous posts I laid out that my RV-7 and I have been tested and we need 650' at a DA of around 6000' to execute a 90-270 turn. In those same conditions on takeoff we covered 7,900' to go from stop to 650' AGL. I calculate that we make about 900' distance toward the runway in the turn.

Note that this discussion is assuming a straight out departure.

So theoretically on a 7000' runway I can make the threshold from 650' AGL in a DA 6000' or less.

But what if the runway is shorter? I'll finish the turn but well short of runway.

Comparing my 7:1 climb ratio beginning at 7,900' from the brakes release point at 650' AGL, with my 11:1 glide I come up with needing an extra 250' AGL for each 1000' increment of runway length less than 7000'

Example: Take off from a 3000' runway. At 650 I can execute a turnaround but will be 4000' short of the opposite runway threshold. I still need about 400' AGL once I finish the turn to glide the rest of the way. So the added numbers look like this: 4(k) * 250' +650' = 1650' AGL required to execute a turnaround and expect to make the threshold of a 3000' runway. Why so high? Because I'll be 2.7 SM from the threshold once I finish the turn around, and those are the numbers required to glide to make concrete.

If it's rural and there is plowed field then a turn around from less than that may be smart. But if it's warehouses at the departure end then it's 1650' AGL or forget about the runway.

To me that is a shocking bit of information! Surely 1,500' AGL is enough to turn back right? Not according to the math if the runway is typical for an RV.

My testing was done in the vein of normal operations. My takeoff wasn't max performance, it was a normal takeoff. My turns weren't practiced extensively, they were done with moderate proficiency. Surely the climb and turn numbers could be tightened up, but these represent what I will likely encounter in an unexpected loss of power on takeoff. Also there will be extra energy remaining the further you get from the runway and the more you can round off that 90-270 into more of a 15-195.

Good argument for VCOA

Food for thought.
 
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AoA Instruments In Certified Training Fleet

The Onspeed device works for our EAB, Vans, but for most of the training fleet comprised of older 172 and Cherokee, the OnSpeed device and precise AoA measurement aren't available. So the GA fleet relies on the power settings and reference speeds. I think this method has worked well for the GA, especially for teaching new pilots.

This is an interesting point. While not related to VAF interests directly it certainly could affect overall flight safety and acceptance in GA overall.

The FAA lowered the threshold and cost of installation in GA aircraft with their in 2014 that allowed installation of AoA systems and appeared to encourage it.

"Press Release – FAA Clears Path for Installation of Angle of Attack Indicators in Small Aircraft"
https://www.faa.gov/news/press_releases/news_story.cfm?newsId=15714

"Approval of Non-Required Angle of Attack (AoA) Indicator Systems"
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/eb0fac0c1641509586257c76005e6274/$FILE/AIR100-14-110-PM01.pdf

I think that it in many cases comes down to: "I don't need it I am an excellent stick and rudder pilot and will never get into that situation", "The dammed C150 isn't worth that much, why should I spend even a few hundred dollars and it?", or "Our students have enough to be concerned about without an additional system to monitor,!", "We don't want/need to revise our training syllabus!", and the excuses go on and on.

Bottom line for me, there is no reason an AoA system could not be installed in every GA aircraft in the fleet if an owner our pilot wanted it. The FAA certainly lowered the barricades back in 2014.

- larosta
 
I think I've got this right, somebody chime in if you see a logical error.

In previous posts I laid out that my RV-7 and I have been tested and we need 650' at a DA of around 6000' to execute a 90-270 turn. In those same conditions on takeoff we covered 7,900' to go from stop to 650' AGL. I calculate that we make about 900' distance toward the runway in the turn.

Note that this discussion is assuming a straight out departure.

So theoretically on a 7000' runway I can make the threshold from 650' AGL in a DA 6000' or less.

But what if the runway is shorter? I'll finish the turn but well short of runway.

Comparing my 7:1 climb ratio beginning at 7,900' from the brakes release point at 650' AGL, with my 11:1 glide I come up with needing an extra 250' AGL for each 1000' increment of runway length less than 7000'

Example: Take off from a 3000' runway. At 650 I can execute a turnaround but will be 4000' short of the opposite runway threshold. I still need about 400' AGL once I finish the turn to glide the rest of the way. So the added numbers look like this: 4(k) * 250' +650' = 1650' AGL required to execute a turnaround and expect to make the threshold of a 3000' runway. Why so high? Because I'll be 2.7 SM from the threshold once I finish the turn around, and those are the numbers required to glide to make concrete.

If it's rural and there is plowed field then a turn around from less than that may be smart. But if it's warehouses at the departure end then it's 1650' AGL or forget about the runway.

To me that is a shocking bit of information! Surely 1,500' AGL is enough to turn back right? Not according to the math if the runway is typical for an RV.

My testing was done in the vein of normal operations. My takeoff wasn't max performance, it was a normal takeoff. My turns weren't practiced extensively, they were done with moderate proficiency. Surely the climb and turn numbers could be tightened up, but these represent what I will likely encounter in an unexpected loss of power on takeoff. Also there will be extra energy remaining the further you get from the runway and the more you can round off that 90-270 into more of a 15-195.

Good argument for VCOA

Food for thought.

I practice off a 6,000 runway near sealevel (128'). On the first take-off of the day I am off in 300 - 400' and make my crosswind turn before 500' AGL. On the next TO I have about 1,200' less so I am still on runway heading when I pull the power at 500' AGL, count 3, prop to low rpm, 90 mph and 45 degree bank into the wind. I maintain 90 mph. It usually puts me back to the runway about midway down. So once I see I have it made it is prop to high rpm and full flaps. I am usually high and fast so the concern is getting it down and stopped before the end of the runway. Also this will be a down wind landing.

Making it back to the runway is nice but most of what is inside the perimeter fence is better than what is outside. Lots of places to land on the airport that aren't runway in a RV, 'specially a tail dragger.
 
Optimum glide with CS MT prop

In a previous post I posted some glide details for my set up.

I did glide testing with no fuel to the engine, prop full coarse, and believe it or not best glide involved better than 12" MAP.

Once I had the airspeed and rate of descent established I went back to idle glides and determined that idle and full coarse (1100 RPM) was adding considerable energy to my glide. In my set up I need to spin the prop at around 1400 RPM (by prop control) at idle power to get a rate of descent close to actual no power glide.

Hard to know how idling the engine compares to a true power loss until you try it. In my case there was a marked difference with the engine at idle and full coarse prop.

Everyone's airplane is going to show different power and glide performance, the key is to know yours cold.
 
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I've been working on this impossibility all summer with loads of practice time. There are obviously a bunch of variables and many of them have a very significant effect.

Here's a video of the impossibility in an RV-4 from 400' AGL (not maximum effort): https://youtu.be/zGY3uTsZ6mk
 
About the same as my RV-4 IO-360 CS prop. I have 6,000' to work with but I am usually way high so prop back to high rpm, full flaps and maybe a slip.
 
I want to add to this thread about an actual successful impossible turn with an engine failure. While this is not a RV specific airplane, I am posting this because I learned a lot from watching this video because a lot of things went right with this emergency landing. There are a lot of video angles from this airplane, from the cockpit view to the outside view.

Airplane: Cessna Turbo Centurion. (Retractable gear. Gear retracted at take off and redeployed during the emergency landing)

Test Condition: 1st test flight after engine overhaul (remember what Mike Busch said about engine overhaul.)

Pilot: He is fully aware that he may have engine problem before the flight and was prepared to land when he encountered the engine failure

Landing: Landing was not on the same runway. The intersection runway was used and it meant he didn't turn as much if he had to land on the runway he took off from.

Picture of the flight track via ForeFlight.


The take off starts at 5 mins mark.

https://youtu.be/9FdRQiHyWQs?t=307
 

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[snip] I am posting this because I learned a lot from watching this video because a lot of things went right with this emergency landing. There are a lot of video angles from this airplane, from the cockpit view to the outside view.

Airplane: Cessna Turbo Centurion. (Retractable gear. Gear retracted at take off and redeployed during the emergency landing)

Test Condition: 1st test flight after engine overhaul (remember what Mike Busch said about engine overhaul.) He blew a rod through the case. The data plate held the case together. :rolleyes:

Pilot: He is fully aware that he may have engine problem before the flight and was prepared to land when he encountered the engine failure. I don't think he expected his newly overhauled engine to hand grenade, but agree he was on guard. He reacted quickly lowering nose and turning left (which was the best direction). He narrates I know you are not suppose to turn back.

Landing: Landing was not on the same runway. The intersection runway was used and it meant he didn't turn as much if he had to land on the runway he took off from. This saved the day. He departed Rwy 30 and landed Rwy 08. If he had to land on same runway Rwy 12, another 40 degree turn would have had him end up short of runway. He landed ON the threshold of the runway (with overrun).

Picture of the flight track via ForeFlight.

https://youtu.be/9FdRQiHyWQs?t=307
Good points. He also got slow in the turn and said in his narration he had to tell himself to push the nose down. That is where pilots FAIL and sadly stall and spin. Pilots close to the ground don't want to push the nose down and fly into a crash, and add task saturation a stall often occurs. I just completed my CFI renewal (15th renewal over 30 yrs) and there was much discussion in the renewal course work about turn backs, LOC (loss of control) and accident statistics.. The statistics show fatalities go way up if turn backs are made below 800 ft. Success rates although not 100% for turn backs at 800 ft or higher, did have lower fatalities.

If your climb rate is less than your glide sink rate you will never make the the runway. If you are light and really climbed at Vy you will be better off than at gross on a hot day.

The "180 degree" turn is really 270 degree if landing on same runway you departed in opposite direction.. Winds are high or obstacles around airport affecting that return decision should be thought of before takeoff and planned before takeoff.

If you lose the engine low and all runway is behind pick a place from 30 degrees left to right, and slow down, add flaps and fly the plane into the crash. If you get to 500 feet* pick a place 90 degrees either side for off field. Below 800 feet return to the same runway is iffy.

*Of course you see STOL planes making videos doing the simulated engine failure and return to runway at lower altitudes.

If you climb out at Vx you may have better luck getting back to runway. If winds are high you may overshoot the runway. If you are pitched to hold Vx and engine quits you better dump the nose NOW.
 
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I want to add to this thread about an actual successful impossible turn with an engine failure. While this is not a RV specific airplane, I am posting this because I learned a lot from watching this video because a lot of things went right with this emergency landing. There are a lot of video angles from this airplane, from the cockpit view to the outside view.

Airplane: Cessna Turbo Centurion. (Retractable gear. Gear retracted at take off and redeployed during the emergency landing)

Test Condition: 1st test flight after engine overhaul (remember what Mike Busch said about engine overhaul.)

Pilot: He is fully aware that he may have engine problem before the flight and was prepared to land when he encountered the engine failure

Landing: Landing was not on the same runway. The intersection runway was used and it meant he didn't turn as much if he had to land on the runway he took off from.

Picture of the flight track via ForeFlight.


The take off starts at 5 mins mark.

https://youtu.be/9FdRQiHyWQs?t=307

I saw that. Guy didn't do himself any favors by dropping the gear before he was sure he had the runway made.
 
The relative long runways worked out for him, 3400 and 4000 feet. From the video, he barely cleared the airport fence perimeter. I also think the airplane was light weight for the test flight. I also think it probably will not make it back at gross. However, there is a lot of flat terrain around the airport. It helps to have all the odds on your side.
 
The way to optimize the turn back is to pull as close as you can to stall without stalling. Of course that is dangerous bordering on insane but that’s what the math says works. Lift is everything and drag is secondary. So unless you pull aggressively you aren’t going to make it. Im not sure what technique was being used in these tests.
 
The way to optimize the turn back is to pull as close as you can to stall without stalling. Of course that is dangerous bordering on insane but that’s what the math says works. Lift is everything and drag is secondary. So unless you pull aggressively you aren’t going to make it. Im not sure what technique was being used in these tests.

Yep. Best glide speed goes out the window in the impossible turn. The size of the turn radius (i.e. distance flown) is what will makes the difference between making the runway or not. Unfortunately, this means flying a steep turn, near stall (think best endurance glide, not best glide angle) with elevated load factor. This is not the best safety recipe for low altitude flight…

Skylor
 
You don't need to fly on the edge of a stall to make it from 500' in a RV-4. Engine out I aim for 90 mph, 45 degrees of bank or so. You can make your job easier by always setting up for a turn back by offsetting down wind (let any crosswind blow you off the center line once a rejected take-off is not an option).
Fly coordinated (no skids near the ground). Start your practice at 1,000 AGL and gradually work down to see what you are comfortable with.
 
Turnback

You don't need to fly on the edge of a stall to make it from 500' in a RV-4. Engine out I aim for 90 mph, 45 degrees of bank or so. You can make your job easier by always setting up for a turn back by offsetting down wind (let any crosswind blow you off the center line once a rejected take-off is not an option).
Fly coordinated (no skids near the ground). Start your practice at 1,000 AGL and gradually work down to see what you are comfortable with.
Finally someone who understands what I have been saying for a long time. In addition if you are in a side by side aircraft, in non crosswind conditions, immediately offset to the right (terrain permitting) so you will be able to keep the runway in sight on the left side in a climb.
The people who say that more than 240 degrees of turn is required are wrong. In my Wittman Tailwind the sink rate gets too high below 75 knots so that is my target speed.
 
Interesting discussion and there may be some misconceptions. All things being equal, weight is not going to change the glide distance. You may have to change speed to compensate for a heavier aircraft and you won’t have as much time to figure things out, but you will end up at the same place on the ground. Wind will play an effect on this too but don’t think you can glide farther just because you’re light.
 
.... Wind will play an effect on this too but don’t think you can glide farther just because you’re light.

Thinking about weight. When flying glider, I get the better glide with more ballast. Given the low glide ratio of these short winged powered airplanes, the gliding distance won't be a factor. The speed will be higher for higher weight though, and it means higher energy at touchdown.
 
Weight

Thinking about weight. When flying glider, I get the better glide with more ballast. Given the low glide ratio of these short winged powered airplanes, the gliding distance won't be a factor. The speed will be higher for higher weight though, and it means higher energy at touchdown.
Good to see someone who understands weight. Weight won't matter much, especially for the two seat and single seat EAB. In a jet airliner say in the 110k max gross weight range, max landing weight approximately 99k, weight with crew and min fuel 65k: At max landing weight the airplane from 30'000' to sea level will typically travel 90 nm in high speed descent. At minimum weight approximately 60 nm. Idle power, 300 kts indicated to 10'000' and then 250. Same principle in glider except the glider pilot plays a guessing game with lift. Heavier weight reduces rate of climb but increases glide performance.
 
Turns

There are people who discuss the turnback as a 90/270 turn. Charlie Precourt in Sport Aviation series on the subject states a minimum of 190 to 210 degrees of turn. The 90/270 has no place in this discussion UNLESS very unusual high terrain or obstruction is involved almost at the departure end of the runway.
 
I'm not sure I would cherish landing in a crowded urban neighborhood. The takeaway is don't stall. If you don't make it back level the wings and land straight ahead at minimal speed. Generally, the stuff inside the perimeter fence is better than the stuff outside with folks there to give you some help.
 
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My turn...

There are people who discuss the turnback as a 90/270 turn. Charlie Precourt in Sport Aviation series on the subject states a minimum of 190 to 210 degrees of turn. The 90/270 has no place in this discussion UNLESS very unusual high terrain or obstruction is involved almost at the departure end of the runway.
There are exceptions.
Many moons ago during my RV4 test period I experienced a significant (90%) power loss just after takeoff from a 2200' grass strip with 50' pine trees at the end. My RV4 takeoff technique was similar to the F16 where we accelerate (rather quickly) in ground effect followed by a steep climb at best rate to cruise altitude.
My RV4 power loss occurred at 200'/100 KIAS just after beginning my best rate climb clearing the departure end trees. After a nanosecond evaluation of my not so attractive options I was able to successfully perform a buttonhook turn used frequently by crop dusters where I grew up to reposition themselves for subsequent spray passes. It involves an immediate 45 degree check turn followed by a constant left slight climbing steep bank 225 degree turn back. Similarly but much quieter I was able to climb slightly while bleeding airspeed to an 80 KIAS glide about halfway thru the turn. I landed opposite direction on the grass strip I had just departed with manual flap deployment just past the (now approach end) trees stopping 3/4 down the runway, surprised onlookers notwithstanding.

Lessons learned were many even with two prior engine failures in single engine aircraft, (one in the F16 and another in a Scout). More than anything else they taught me to stay calm, take a breath and evaluate your options.
Practicing my engine failure takeoff profiles at higher altitudes previously also helped immensely. Being light on fuel with no pax was also a positive factor.

Like all the old instructors said, when something bad happens, fly (not stall) the airplane!
:)
V/R
Smokey
 
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Misc

Smokey-
You bring up some good points. Watching Bob Hoover in the Shrike with both engines shut down was my recurrent in energy management. I tend to go to 130 knots in a shallow climb for cooling. If the engine quits while I am in the shallow climb I will continue to climb until approaching my personal maneuvering speed of 90 knots. Then I will lower the nose as necessary. While that is taking place I will turn as appropriate.
A Long time ago in the Pitts S1S I was getting ready to start an airshow(air start). I was approaching about the 1000' mark of the single runway at a 90 degree angle, at treetop height and Vne, which is 203 statute in the S1S. Close to the runway the engine suddenly shook violently and I pulled up to about 500 AGL with throttle at idle. Rolled into a steep left turn that continued to short final. Made the runway with room to spare. Somewhere in the process I switched mags and the engine ran normally but I elected to leave the power at idle. 3000' runway, a right turn and slow to land would not have worked.
I get to watch the ag pilots frequently, I am based on a ag airport. Their turnarounds appear to often be banked 60 degrees or a bit more.
For those who feel a 45 degree bank close to ground is suicidal perhaps they should choose another hobby.
I have a vague recollection from half a century ago of practicing turn arounds in the Wittman Tailwind from 300 AGL. I had just over 300 hours total flight experience. Did I practice first at a safe altitude? Of course not.
 
Turnbacks

First three items on the engine failure checklist:
1 Fly the airplane
2. Fly the airplane
3.Fly the airplane
 
Bad Outcome

On Sep 12, a new hangar neighbor who I had not met took off from the AG strip to go to another airport for fuel. On takeoff after fueling, 8000' runway with additional overruns ADSB shows the airplane losing speed at around 100' AGL, with significant runway remaining. A turn to the right with and then a continuously steepening left bank back toward the runway, bank angle increased to 90 degrees and the airplane crashed wingtip first and burned. Pilot was by himself an was killed.
The most bothersome thing is that he had plenty of runway to land straight ahead. He might have gotten stopped or he might have gone thru the fence.
Cessna 177RG, there was no hope of making the turnaround. There was also a recent history of engine problems that the pilot was working on.
Camshaft and lifters trashed and broken rings in two cylinders. 600 plus hours since cam was replaced, but it appears the airplane then was inactive until the accident pilot purchased it.
Detailed preliminary report on Kathryns report.com, Sep 12.
 
Weight and Turn Back

Interesting discussion and there may be some misconceptions. All things being equal, weight is not going to change the glide distance. You may have to change speed to compensate for a heavier aircraft and you won’t have as much time to figure things out, but you will end up at the same place on the ground. Wind will play an effect on this too but don’t think you can glide farther just because you’re light.

While this is true, this is another area for a potentially fatal misunderstanding when applied to the engine-out turn back. While increased weight will not affect best glide distance, it WILL increase the altitude required to make a successful engine out turn-back. This is due to the increased glide speed and stall speed which both work against you to increase turn radius thus increasing the distance flown in the turn.

Skylor
 
Here's one that popped up in my FB feed from only a few days ago.

What looks to be a -210 on a post-overhaul break in flight certainly broke something, suffering a catastrophic engine failure very shortly after takeoff. Fortunately the runway layout allowed a safe return - no report on the condition of the pilots seat cushions though. ;)
 
Degrees of turn required for turnback depends...

...on the distance from the end of the runway the turnback maneuver begins. If it's within 5 turn radii, it will take some extra maneuvering (degrees of turn) to align with the runway:

3c039a_96e36f89d3224e8a9726b123b385ae87~mv2.png


For a sense of scale, this runway is 3000 feet long and begins just inside the picture.

The turn reverse to align with the runway requires a relatively healthy "unload" (reduction in AOA) to avoid a stall.

It would also be practical to turn less, overfly the hangers on the north side of the runway (bottom of the picture) and touchdown further down the runway, provided sufficient runway was available for stopping. The landing roll could be shortened with an intentional ground loop.

Fly safe,

Vac
 

The Navy teaches its officer this turn maneuver when retrieving man overboard. The goal is to have the ship returning 180deg back to its previous wake in the middle of the ocean absent of any reference point from land, or GPS.
 
If you allow your airplane to drift downwind off the centerline after landing isn't an option, a turnback into the wind will bring you back much closer to being aligned with the runway. I make it a part of take-briefing, turn back altitude, which way and where landing is no longer an option.
 
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