Lift Reserve Indicator

[dcstrng]

My next flight, I'm planning on getting to a safe altitude and practice emergency turn backs using the LRI. Find out where the demons are and what is the minimum altitude I can safely do it.

Would be very interested in what you find out... Fortunately I’ve never had to do this for real, but in my C150s I think I pretty much used 500’ and felt uneasy with that (alright, I’m a wimp…) cuz of high-tension lines where I used to fly

[MichaelFarley56]

My next flight, I'm planning on getting to a safe altitude and practice emergency turn backs using the LRI. Find out where the demons are and what is the minimum altitude I can safely do it.

It's actually interesting you say that...it jogs a memory from back in the day. Does anyone remember "Wide World Of Flying" videos? I remember Barry Schiff did a bunch of videos, and one episode dealt with this exact same thing.

In the video, Barry's recommendation was to take off, climb out normally, and once at a safe altitude perform a test to determine how much altitude you would loose if you had an engine failure on takeoff. The test was to establish yourself in a climb, pull the engine to idle, then while pitching down to maintain airspeed wait 3 seconds (for the reaction time), then use an approximate 45 degree bank turn to complete one 360 degree circle, execute a simulated "flare", and see how much altitude was lost. This would give you a rough idea of how much altitude you'd need to even attempt the turn back to the runway since, if you do this for real, you actually turn more than just 180 degrees. He went on to describe how a 45 degree bank turn was about the best compromise between turning radius, rate of turn, and increase in stall speed.

I haven't done this test but at some point I'd like to, just to see what the results are. Something to try this summer maybe.

[vigilant104]

In addition to the "can I get turned back around without stalling" question, there's also the issue of whether we would have enough remaining altitude to make the runway once the turn is complete. Like many, on warmer days I keep the nose down and the airspeed up on climbout in order to keep CHT's in check. That can result in significant ground distance covered before I reach 1000' AGL. Heck, if we climb at 500 fpm and 90 MPH, that puts us at a ground distance of over 9,000 feet from the takeoff point when we reach 700' AGL, so at the advertised 11:1 glide ratio we can only glide 7,700' over the ground: Quite apart from the altitude lost in the turn and the chance for an accelerated stall in the turn, under this scenario we wouldn't even make it back to the takeoff point even if we were already pointed in the right direction when the engine quit.
It's no good to get turned around, then be at 200' AGL (with the wind now at your back :( ) and still needing to land in the trees.

Hmm--maybe I should accept some higher CHTs during the first 2 minutes in order to gain some altitude for mom and the kids. And think long and hard before rejecting any acceptable landing location that is out front.

Yes, some experimenting at safe altitude on my part is definitely in order.

[fastj22]

I recently did spin training in a Decathelon. the most altitude I lost in spin recovery was 1500ft in an inverted spin and at least 4 revolutions. Most of it was disorientation. For those of you who haven't done spin training, I highly recommend it. It will give you real respect for what a plane does when it quits flying. Spin close to the ground and you will die.

I haven't spun my Waiex yet, but eventually the weather will allow me to try it soon.

Here's my test plan. Take off and get at least 3000 AGL. Set my altitude bug to my altitude (virtual field elevation). Start a typical Vy climb simulating a power climb. 300 ft above the bug, pull the power (simulate engine failure) and execute a 180 turn keeping the plane in Vy using the LRI. How did it work? Low or high? Now do it again. This time increasing my turn rate to the point of stall/spin. Eventually spinning it. Repeat until I can just do the 180 turn without spinning. That will tell me the minimum altitude required to execute a 180 turn without an engine and without a spin.

[radfordc]

It's actually interesting you say that...it jogs a memory from back in the day. Does anyone remember "Wide World Of Flying" videos? I remember Barry Schiff did a bunch of videos, and one episode dealt with this exact same thing.

In the video, Barry's recommendation was to take off, climb out normally, and once at a safe altitude perform a test to determine how much altitude you would loose if you had an engine failure on takeoff. The test was to establish yourself in a climb, pull the engine to idle, then while pitching down to maintain airspeed wait 3 seconds (for the reaction time), then use an approximate 45 degree bank turn to complete one 360 degree circle, execute a simulated "flare", and see how much altitude was lost. This would give you a rough idea of how much altitude you'd need to even attempt the turn back to the runway since, if you do this for real, you actually turn more than just 180 degrees. He went on to describe how a 45 degree bank turn was about the best compromise between turning radius, rate of turn, and increase in stall speed.

I haven't done this test but at some point I'd like to, just to see what the results are. Something to try this summer maybe.

In my Sonex it can be done in less than 400'.

[MichaelFarley56]

Very cool Charlie! That's an impressive number. What speed do you use as best glide speed?

[radfordc]

In addition to the "can I get turned back around without stalling" question, there's also the issue of whether we would have enough remaining altitude to make the runway once the turn is complete. Like many, on warmer days I keep the nose down and the airspeed up on climbout in order to keep CHT's in check. That can result in significant ground distance covered before I reach 1000' AGL. Heck, if we climb at 500 fpm and 90 MPH, that puts us at a ground distance of over 9,000 feet from the takeoff point when we reach 700' AGL, so at the advertised 11:1 glide ratio we can only glide 7,700' over the ground: Quite apart from the altitude lost in the turn and the chance for an accelerated stall in the turn, under this scenario we wouldn't even make it back to the takeoff point even if we were already pointed in the right direction when the engine quit.

Mark, you're calculations are for a no wind condition, right? Climbing into a headwind will improve your ability to make it back to a runway behind you.

[vigilant104]

Mark, you're calculations are for a no wind condition, right? Climbing into a headwind will improve your ability to make it back to a runway behind you.

Charlie,
Yes, you are right, and I didn't account for that Taking off into a headwind improves our ability to make it back to the runway . . . and it increases the adverse consequences if we don't make it. Assuming an airspeed of 40 MPH when we enter those trees or crops, we'll have over 2.5 times more kinetic energy to dissipate if we have a 10 MPH tailwind compared to a 10 MPH headwind.

The point I came away with is that increasing the climb >angle< on takeoff (closer to Vx rather than Vy) may give me more options if things go wrong within the first minute of flight.

[radfordc]

Very cool Charlie! That's an impressive number. What speed do you use as best glide speed?

Somewhere around 70-75?

[Rynoth]

The point I came away with is that increasing the climb >angle< on takeoff (closer to Vx rather than Vy) may give me more options if things go wrong within the first minute of flight.

There's nothing more useless to a pilot in an emergency than the sky above you!

I'm sure that some aircraft can't return to the airport with an engine failure no matter how far they fly in a straight line, if the climb gradient is shallower than the glide radio. A fully loaded Sonex with an Aerovee might be one of them. I think the best takeaway from this discussion on the turnback maneuver is to test and practice it in the aircraft you're flying, long before you ever might need it. Then you'll know for sure when/where your point of no return becomes your point of safe return.