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Required Altitude for Engine Out Return to Airport

N876RV

I'm New Here
Group,

I've completed my Phase I on my RV-7A and did several tests to determine the amount of altitude I needed upon an engine out situation to perform a turn and land back at departure airport. Of course I did these tests at 4,000 ft and the engine wasn't really out, but at ~800 rpm. I have a fixed pitch "cruise prop".

The altitude that I've settled on for a safe return to the airport is 1,200 ft. My numbers during the tests were less than that, but since the prop was still spinning at low RPM I decided to bump up the number to the 1,200 ft value that I now use. Anything less than that and I tell my self that I will "lower the nose and land straight ahead." I would like to compare this to what others have determined.

Jeff
N876RV
 
Too many variables to use altitude alone.

Altitude is one. F/P or C/S is two....... you got both of those.

Add to it,

Density altitude
Distance from the runway for a given altitude
IAS at failure
Aircraft pitch attitude at failure
Wind
Pilot reaction time
Pilot technique
 
Group,

I would like to compare this to what others have determined.

Jeff
N876RV

Too many variables to use altitude alone.

Altitude is one. F/P or C/S is two....... you got both of those.

Add to it,

Density altitude
Distance from the runway for a given altitude
IAS at failure
Aircraft pitch attitude at failure
Wind
Pilot reaction time
Pilot technique

With all the above factors, I would not turn back in my RV unless I was somewhere between 1,500 and 2,000 AGL. This is after more than 2,200 hobbs hours in the airplane.
 
A main variable is what the descent angle is to the airport, which really means what climb angle did you depart at? I did some testing last year at altitude, and concluded forget it.

I think one would have to climb at a very slow airspeed to get high enough, yet close enough to even consider it. The only time I can climb steep enough is when it is very cold out, as cht will limit how long I can climb at 80 knots. And, the runway must be long (to allow more climb before crossing the departure end). If I climbed that way to about 1500', I could turn and land downwind. Maybe. Most climbs are much faster airspeed, so forget it.
 
Guys,

I am amazed at the numbers you are quoting. I can reliably execute a 180 degree turn from my normal climb speed (130mph) and lose no more than 400ft. As I took off well inside the boundary fence, and the wind is blowing me back toward the airfield, I conclude that I will turn back to the airfield if my engine fails at over 400 ft above airfield elevation. Below that I will land ahead.

I have thought about this at length. Many airfields have the Fire Department on the field. All are relatively open with few obstructions. If I'm going to crash I would rather do it on the airfield than elsewhere. So I would rather land down wind on the airfield I just left than into wind somewhere off the field. To minimize altitude loss I have found it is important to initially fly a level decelerating until reaching your glide speed (mine is 100 mph). Optimum bank angle is best found by experimentation at height - I use 30 to 40 degrees - more and the rate of descent builds, less and the turn takes too long. Make sure you maintain speed throughout the turn - the nose can be considerably lower than 'normal'. The rate of descent will be higher with a dead engine, but I have a coarse pitch FP so I'm assuming it won't have that much effect.

If I have more than 400 ft then I am more certain of making the runway. If I can make it to a position where I am 500ft aal and abeam a part of the airfield where I can land, but going down wind, I know that I must turn in now to be able to complete the turn and land into wind.

Pete
RV-6A, O-320, FP
 
Pete, I did similar testing in an RV7 and found also 400ft is what was needed that day. 30 degree angle seemed best as well. I have to admit I was very surprised that I could do it consistantly in about 400ft. In my mind I have put 700ft as my go around number. With an instructor we did this a couple times at an airport with a tower in a 172 , the engine went to idle at 700ft agl and we made it both times easily.
 
Pete (and others),

This is one of those never ending debates, do a search and you will find plenty of posts on the subject.

The turn back to the airport is not a 180 degrees, as that will not line you up with the runway. It is more like a 360, 270 turning in one direction and another 90 turning the other way to line you up.

The other critical factor is how long it takes the pilot to realize they have an engine failure and then how long it takes for that pilot to take the correct action.

That delay can cause you to lose a lot of altitude. I argue it is still best to land straight ahead, with minimum turns. In addition, you only need to see one plane stall and spin in when trying to return to the airport from which they just departed to convince you the turn back is not a good choice.
 
Pete (and others),

This is one of those never ending debates, do a search and you will find plenty of posts on the subject.

The turn back to the airport is not a 180 degrees, as that will not line you up with the runway. It is more like a 360, 270 turning in one direction and another 90 turning the other way to line you up...
This points up something that is learned early when flying gliders. If you have any contemplation of turning back in your RV (I don't), be aware that the worst place to be, after departure, is on the runway centerline. If there is a crosswind, you need to drift downwind of the centerline, otherwise you need to make a gentle turn one way or the other. If you do this, maybe all you will have to do is make near a 180, otherwise, it is much more than that.
 
....and you will...

This points up something that is learned early when flying gliders. If you have any contemplation of turning back in your RV (I don't), be aware that the worst place to be, after departure, is on the runway centerline. If there is a crosswind, you need to drift downwind of the centerline, otherwise you need to make a gentle turn one way or the other. If you do this, maybe all you will have to do is make near a 180, otherwise, it is much more than that.

...also be in a better position to use a crosswind runway, if there is one.

Like Larry, taught from my glider training...:)
 
Many of you are gritting your teeth because you knew I would have to pile on here, so here goes....

BTW, I just soloed a glider today and I demonstrated the turnback at about 400 feet in the glider without any problem, but it is an entirely different animal......

I will repeat what I have said here many times, the turn back after take-off is a doable manuver, the problem is that most pilots dont pull it off and when they fail, the consequences are death.

There is no way to practice this manuver that simulates the adrenaline rush that sqaushes all fine motor movement and most of the time the results are stall, spin, crash, burn, die.

Turn to the downwind and then if you are on downwind and you cant make the runway, land on the airport property into the wind. If you dont have the alt to crash headed into the wind, do not turn back.

Tailwinds,
Doug Rozendaal
 
The turn back to the airport is not a 180 degrees, as that will not line you up with the runway. It is more like a 360, 270 turning in one direction and another 90 turning the other way to line you up.

This assumes that you are going to line up on the takeoff runway.

As Penguin said, anywhere on the airport property is preferable to anywhere OFF the airport property. If the engine goes on takeoff, I'm going to be much less concerned with lining up on a runway as I would be with lining up on any flat stretch of clear grass, taxiway, apron, ramp, etc. Runways are only for NORMAL ops, and RV's do well on flat grass with short rolls. There are lots of options on most airports. File the NASA form, call the insurance company, and don't worry about it.

All you really have to do is get it down and stopped. Painted asphalt is only advice at that point, not a requirement.
 
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The turn back to the airport is not a 180 degrees, as that will not line you up with the runway. It is more like a 360, 270 turning in one direction and another 90 turning the other way to line you up.

Not quite that bad. If you departed straight out, you would need to make a 180 plus another 45 that's 225* then turn back 45* to line up with runway. A total of 270*.

You could place the odds in your favor by departing (after you pass the end of the runway) on a 45* Then you would only need a 225* turn to line up with the departed runway.
 
Turning Back To Land

Hey Doug I turned back at a 250 feet :cool: twice in glider training and accomplished the maneuver just fine. What I learned while getting checked out in gliders, and from my military instructor experience, is that you should be thinking about it on every departure. I also practiced when I broke off the tow airplane a turn in the other direction just as if I had a problem and broke off at 250 ft.

The practice braking off at 2500' gave me the confidence and ability to accomplish the maneuver at 250'.

I don't have my RV done yet, and hopefully someday I will, but will practice engine out maneuvers as well as think about what the best course of action is at each airport for emergency return.

One more thing.....in glider training you think about winds a whole lot more. If you have a left x wind you make your emergency return, if you can, to the left as it will keep you closer to the runway on return. Just food for thought.
 
Here are some videos I made....

....last year, of turnbacks in my 180HP -6A from 800, 600, 400 and 250'.

http://www.youtube.com/watch?v=YdZ1s-2uvFo ......You're pretty new on here but those are valid questions to ask. I discovered that in a quick turnback from 800', I'd overshoot the oppostie end of the runway and had to go-around because these RV's climb so fast and you're high at the departure end of the runway.

I crop-dust for a living and turnbacks are part of my job...hundreds of them daily, so practise on your own and take what I say with a grain of salt.....determine you own ability, as I did. These airplanes have more capability than most of their pilots and the time to do any turnbacks is not when the chips are down, without first having practised them....caveats..,

Regards,

Edit: For these turnbacks, I set the altimeter to zero feet and counted to 3 after I reduced power, to simulate the delay probable in making a decision at such low altitudes...the 250' turnback was my personal limit...a very tight, have-to-do-correctly, procedure.

Practise, practise...
 
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For A-models "turn back practice" might be a life saver

During researching A-model flip-overs, on the internet, I came across well over 400 accidents/incidents with Vans aircraft, so far. I will post my findings in a separate thread later.

However, from all the accidents with A-models, that I could find, that made an off field landing, every one flipped onto its back! Read again: every one nosed over, every single one! So to me that means, if there is a chance of getting back to the airport, to any runway, taxi way, apron, etc. it is always better than landing in a field. Because the statistics say that you are going to nose over! You are certainly better of with emergency crews, fire brigade or even just a couple of people around, that can help you out of the wreck if you still flip over when landing on the airfield (on grass / turf / dirt). Of course the ?turn back? needs to be well trained and you need to know your decision height. Nosing over, at low speed, after a successful off field landing, straight ahead, is still preferred over a stall, spin, crash and fire, at the end of the runway.

Anyhow, it is one of those things I will be practicing, given the poor performance of the Vans nose gear.

Regards, Tonny.
 
Hey Doug I turned back at a 250 feet :cool: twice in glider training and accomplished the maneuver just fine. What I learned while getting checked out in gliders, and from my military instructor experience, is that you should be thinking about it on every departure. I also practiced when I broke off the tow airplane a turn in the other direction just as if I had a problem and broke off at 250 ft.
The best way to get a 200 ft rope break is to not call "200 feet" along with your proposed plan of action, "e.g., 200 feet, would make a teardrop to the left to land downwind in the grass". The other sure-fire way is to have a sneaky instructor. I've experienced 200 foot PT3s (permature termination of the tow) for both reasons.

The point here is that you should always be thinking not about just the decision height, but what you're going to do on this flight if you have to turn back. Wind, runway configuration, traffic density and your departure path will all affect the ideal plan of action.

A lot of people have talked about overshooting with turn-backs. It's certainly possible. In the glider, once I have the runway picked up and am rolling out, I unlock the airbrakes so I can apply them as necessary. On a power airplane, this probably means slipping or flaps, but be careful of ballooning and pitch changes that come with flaps.

I haven't heard many folks talk about the importance of lowering the nose. You need to keep the airspeed up, and it's better to turn faster than stall and spin. You can convert that airspeed back into distance if necessary.

TODR
 
However, from all the accidents with A-models, that I could find, that made an off field landing, every one flipped onto its back! Read again: every one nosed over, every single one!

I know of one 7a that landed in a bean field with no damage other that what was caused by engine parts hitting the cowl when the engine failed. So there is at least one exception to your findings.
 
I know of one 7a that landed in a bean field with no damage other that what was caused by engine parts hitting the cowl when the engine failed. So there is at least one exception to your findings.

I know of an -9A that had an engine failure as well, about 1 1/2 years ago in the Ottawa area, landed in a snowy field. It did not flip on its back.
 
Probably much-much lower than 1200'

Last year there was a very long thread on the subject:
Return to runway after engine failure

Like many of these discussions, the noise level was very high so you'll have to do some careful reading to sort the facts from the hysteria.

I worked up a spread sheet to calculate minimum turn back altitude in my airplane. Here is what I came up with:
My assumptions:
-1000 foot takeoff roll
-climbing 1000fpm @ 80KIAS
-Glide speed 75KIAS
-Decision Time 3 seconds
-0 wind
-Turn is 225 degrees one direction, short straight line, then 45 degrees the other. All turns at 45 degree bank angle
-Altitude lost during turn is 335 feet
-Time to turn 21.5 seconds
-Turning radius 486 feet (be sure not to hit anything)

Pierre's empirical results on his 6, blew out my theoretical numbers for a 9. Obviously my spread sheet was overly conservative. Some of that could be take off head wind (normal) which adds margin, but some is just that my model is not exactly right.

However, this is not just about the theoretical capability of the airplane. Comparing my empirical results, it is obvious he's better at this than I am.

Testing at altitude I was able to do it in under 400. I tried it once at an airport from about 700' AGL and badly overshot the runway. I had way too much altitude and airspeed. I should have put in some flaps earlier. If my life had depended on it, I would have cranked in a dramatic slip and made the runway.

I believe I could do it in a pinch from anything over 600. Using 60 degree bank will give better results, but also lowers the margin of safety. My limit is 45 degrees for this maneuver.

Under 600' it depends on the airport. At some airports you could do a 90 degree turn and stay on the field. In some cases off field choices could start looking better.

For me, the pucker factor was very high even at 700 AGL. I know that with more practice I can lower the pucker factor.

Couple of things come out of this for me:
1-The airplane is more capable than I am. It can be done from very low altitude, I just need to act decisively and correctly if I loose the motor
2-The fact that Pierre could do it in under 300' AGL is not really going to help me when I'm at the controls. It gives me something to strive for, but I need to be very clear about what I am able to do.
 
However, from all the accidents with A-models, that I could find, that made an off field landing, every one flipped onto its back! Read again: every one nosed over, every single one!

As has already been mentioned, this is completely and totally wrong. There have been a number of incidents where 'A' models landed off-field and the nose gear held up fine. I am personally familiar with an RV-6A that landed in a bean field, parallel to the furrows and the airplane stayed upright.
 
As has already been mentioned, this is completely and totally wrong. There have been a number of incidents where 'A' models landed off-field and the nose gear held up fine. I am personally familiar with an RV-6A that landed in a bean field, parallel to the furrows and the airplane stayed upright.

And the three taildraggers that (semi) landed off runway around here.............ended up on their backs. My local survey was only three; so it looks like 100% for the TW's! :D

L.Adamson --- RV6A
 
so predictable

And the three taildraggers that (semi) landed off runway around here.............ended up on their backs. My local survey was only three; so it looks like 100% for the TW's! :D

L.Adamson --- RV6A

Ah, the defender of "less than robust" nosegear has arrived.

I wouldn't have commented except for the addition of the 'smiley' on reporting your local survey of 3 planes on their backs.
 
Very good, Steve...

Last year there was a very long thread on the subject:
Return to runway after engine failure

Couple of things come out of this for me:
1-The airplane is more capable than I am. It can be done from very low altitude, I just need to act decisively and correctly if I loose the motor
2-The fact that Pierre could do it in under 300' AGL is not really going to help me when I'm at the controls. It gives me something to strive for, but I need to be very clear about what I am able to do.

...and to the point. I didn't dilly-dally when the throttle came back...and in reality, that's not fair because I was expecting it...much different than a real-life scenario and the pucker factor wasn't very high.

Bear in mind that I laid in the ailerons with a wallop, (the roll rate is fast, BTW) simultaneously lowering flaps for the 250' turnback...it was a very quick roll and nose drop...then again, I had just had three or four other turnback practises a few minutes earlier and I was getting a feel for this...not much different than what I do spraying, pullups and descending turns back into the field (38 years of this). Your admonition to fly to your skill level is also what I advocate...not monkey see-monkey do flying....you'll hurt your self.

Regards,
 
Thank you Pierre for the videos! Wow! Some how I missed these when you posted them last time. How much additional safety factor would you add for a dead engine rather than an idling engine. At a number like 800 ft would you think it better to go down wind and land up wind?
 
PUSH, PUSH,PUSH the stick>>

The Big question is "How long will it take you to transition from a nose up climb attitude to a nose down glide attitude?" All of the above scenarios were pre-planned and did not include the "HOLY S--T" factor. How long will it take your brain to decipher what just took place and how much air speed will you blead off during this critical time? I say do all the number crunching at a safe altitude and once you are satisfied with a safe AGL altititude for a return to airport turn....TRIPLE IT. Unless you are over a densely populated area the popular opinion of many experts says that flying straight ahead with maximum control will greatly increase your chance of survival. Period.
 
Edit: For these turnbacks, I set the altimeter to zero feet and counted to 3 after I reduced power, to simulate the delay probable in making a decision at such low altitudes...the 250' turnback was my personal limit...a very tight, have-to-do-correctly, procedure.

Practise, practise...
Pierre, you are the MAN!

I didn't see these last year, got tired of all the noise in that thread.

You have confirmed all of my observations, including you may well run out of runway long before you run out of altitude!

I've practised down to 400', and felt there was room left below that, but flying out of a towered field in the middle of the City of Detroit, I did not want to scare the folks in the tower any more than needed (They said they enjoyed the demonstration!)

I've always believed that if I could teach 14 year old kids to do this manuever at 200' in a 18:1 glide ratio glider, 400' should be a no brainer to an accomplished RV driver!

I do disagree with one thing you did say; Instead of Practise, practise, I believe it should be:

Practise, Practise, Practise, and then practise some more!
 
I believe the consensus after the last time this subject went around is there is no given altitude that will work every day, the variables are many. If those variables are not factored in accurately when and if the maneuver is attempted, the outcome won't be good.

To each his own. I am comfortable with a basic premise it is safer landing straight ahead than turning back. Stick forward and fly into the crash as far as possible is not a bad policy all things being considered.
 
I believe the consensus after the last time this subject went around is there is no given altitude that will work every day, the variables are many. If those variables are not factored in accurately when and if the maneuver is attempted, the outcome won't be good.
Absolutely. That's why you need to think about what could happen on each and every flight. You should be surprised when the engine cuts out, but you should also be ready.

In the glider, we are taught and teach to always have your left hand on the airbrakes with your fingers on the release until at least 200 ft. I have seen in-cockpit video of world-class soaring pilots in competitions, and their faces relax once they reach about 200 ft. A 3 second reaction time is probably right for power since the return-to-runway is not commonly practiced. 3 seconds would be slow in a glider for a 200ft PT3.

Plan for the worst, hope for the best.

TODR

PS - Sorry if it sounds like I'm pushing soaring skills so much, but soaring has made be a better power pilot and my power background has brought good things to share with glider pilots. We have things we can learn from each other.
 
Sorry if it sounds like I'm pushing soaring skills so much, but soaring has made be a better power pilot and my power background has brought good things to share with glider pilots. We have things we can learn from each other.

Yes, Yes, Yes... If anyone has a BFR due, a weekend in a glider is a GREAT investment. I'm sure the neighborhood glider school would be happy to have you.
 
Even more accidents?

Bob, Alfio, Jamie,

That is bad to hear, not that I am wrong, but that there is even more than the 421 accidents, than what I found on the internet, so far, causing a devastating 163 fatalities! I knew that I did not find all the incidents/accidents, because there was only 5 nose gear damages that happened outside the USA or Canada. There have to be more than that, considering the amount of Vans aircraft flying in the rest of the world.

Out of all these accidents, 66 A-models, had a nose gear failure/damage and 55 of them flipped over. I would be careful, since all 9 off-field landings with A-models, that I found, flipped! I did not include flips that occurred due to hitting a ditch, or due to leaving the tow-bar or gust lock on, either.

Could you please let me know details of the accidents that you are referring to (date, N-#, engine type, cause of accident, damage to airplane, pilot total time and time on type), so I can add them to my list (or a link to a website with areport).

Anyhow, let?s be careful and get the statistics down.

Regards, Tonny
 
The way I see it, most normal takeoffs involve a turn onto to crosswind at 500 ft rather than a straight out departure. So the most likely scenario with an engine failure on takeoff and at over 500 ft would be a turn-back from the crosswind leg. Like Steve in post #20, I have found that I can do the turn back from 400 ft in my 9A in ideal conditions. My standard operating procedure now is to depart with a turn to crosswind (even if a straight out departure would be more obvious) and the completion of the crosswind turn becomes the point from which I will contemplate the turn back. This means that I will be attempting the turn-back with 90 degrees of the turn already complete and with at least about 600 to 700 ft AGL. Depending on traffic and my direction of departure, I then like to do a close downwind leg to keep near the runway. YMMV

Fin
9A
 
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....last year, of turnbacks in my 180HP -6A from 800, 600, 400 and 250'.

http://www.youtube.com/watch?v=YdZ1s-2uvFo ......You're pretty new on here but those are valid questions to ask. I discovered that in a quick turnback from 800', I'd overshoot the oppostie end of the runway and had to go-around because these RV's climb so fast and you're high at the departure end of the runway.

I crop-dust for a living and turnbacks are part of my job...hundreds of them daily, so practise on your own and take what I say with a grain of salt.....determine you own ability, as I did. These airplanes have more capability than most of their pilots and the time to do any turnbacks is not when the chips are down, without first having practised them....caveats..,

Regards,

Edit: For these turnbacks, I set the altimeter to zero feet and counted to 3 after I reduced power, to simulate the delay probable in making a decision at such low altitudes...the 250' turnback was my personal limit...a very tight, have-to-do-correctly, procedure.

Practise, practise...

Pierre's videos are interesting.

I did want to point out that he has a fixed pitch prop. The fixed pitch prop's we typically use on RV's have a lot of pitch. Even at a slow idle they have a surprising amount of residual thrust (this is one of the reasons some rv pilots say a fixed pitch RV is more difficult to land...it's not, just different).
I think Pierre would find a totally different result if he actually pulled the mixture to cut-off.
My point is...testing without actually cutting power is not a realistic simulation. An RV at idle with a constant speed prop, the simulation will be more realistic, but still not the same as with a total loss of power.
 
My point is...testing without actually cutting power is not a realistic simulation. An RV at idle with a constant speed prop, the simulation will be more realistic, but still not the same as with a total loss of power.
I fully agree with Scott's point. Testing at idle may help point out optimum speeds, bank angles, techniques, etc. But it doesn't tell you too much about minimum altitudes, or whether you would end up too high or low after the turn around to make the runway.

Pierre - It would be interesting to get some data on how stabilised descent rate is affected by idle vs mixture ICO. Overhead a suitable airport of course.
 
I think it is fairly realistic

.....
My point is...testing without actually cutting power is not a realistic simulation. .......

Check this thread:
My 9A Became a Glider Today

Here are Scott's numbers from that post with prop stopped:
70 MPH equals 400 FPM
75 MPH equals 500 FPM
80 MPH equals 600 FPM
85 MPH equals 750 FPM
90 MPH equals 1000 FPM

Here are ,mine with engine at idol:
75 MPH 556 FPM
81 MPH 625 FPM
86 MPH 652 FPM
92 MPH 714 FPM

The reason behind the differences are not intuitive to me.
My sink rate is worse at 75 MPH I would expect it to be better because at that speed the engine at idol would be closer to "keeping up" with airspeed. Likewise at around 90 MPH my sink rate is better. I would have expected it to be worse because at higher speed there should be more engine braking.

Either my intuition needs adjustment or this is due to pilot technique, up/down drafts, etc. Either way the number are pretty close.

I plugged in his worst sink rate into my turn-back spread sheet and got 583 feet as the minimum turn back altitude. That sheet has conservatism built in. For example, a 3 second decision time and no wind.

By the way, when I have practiced this at altitude and once at an airport, I used a 3 second decision time.

Last year one pilot suggested the only realistic way to test turn back altitudes is to actually kill the motor at an airport and land safely. I'd say that is a little like saying the only way to practice in flight fire scenarios is to actually torch your airplane.

This year I'm planning to do some engine off, prop windmilling glide tests AT ALTITUDE to see what I get. In a turn back situation I think stopping the prop is not an option.
 
Yep, Kevin....

Pierre - It would be interesting to get some data on how stabilised descent rate is affected by idle vs mixture ICO. Overhead a suitable airport of course.

......it's on my list of "to do" stuff, however, given the few seconds the whole maneuver takes kinda makes whether the prop is turning or not, a moot point from such low altitudes, doncha think? I didn't have much time for anything but lowering the flaps and trying to maneuver to get lined back up with the runway. You get rather busy doing this:)

Regards,
 
Check this thread:
My 9A Became a Glider Today

Here are Scott's numbers from that post with prop stopped:
70 MPH equals 400 FPM
75 MPH equals 500 FPM
80 MPH equals 600 FPM
85 MPH equals 750 FPM
90 MPH equals 1000 FPM

Here are ,mine with engine at idol:
75 MPH 556 FPM
81 MPH 625 FPM
86 MPH 652 FPM
92 MPH 714 FPM

The reason behind the differences are not intuitive to me.
Possible reasons for differences:

  1. One or both pilots used the VSI rather than altimeter and stop watch. VSIs are often quite inaccurate. I had a long series of communications with a guy who was claiming 5000 ft/mn climb from a Debonaire with 300 hp engine. When I reported that something was wrong, as the laws of physics simply wouldn't allow this, he sent a VCR tape showing the VSI in a sustained 5000 ft/mn climb. But, the altimeter was also in the view, and it was increasing at about 1600 ft/mn.
  2. Effect of unstable air (updrafts or downdrafts) on one or both data sets.
  3. Effect of changes of wind with altitude on one or both data sets. The wind will be changing as you descend. If you go through an increasing headwind, for example, that will cause an increase in the ASI reading. You will raise the nose to get back to the target speed, and the descent rate will be lower in this period that the nose is raised. To minimize the effects of wind changes, you should do the descents on a constant heading which is at 90 degrees to the average wind. Do two descents at each airspeed, with the second one at 180 deg from the first one. Record the time to descend through the test altitude block, and calculate the rate of descent for each run. Average the rates of descent for the two runs at each airspeed.
  4. Inadequate stabilisation on the test points for one or both data sets. Ideally, the altitude block would be big enough so each run lasted two minutes or more, with the ASI within 1 kt of the target value the vast majority of the time. If you can't do that, it would suggest poor air quality, or more practice required. Note - flying to this accuracy takes a lot of concentration, and your lookout will suffer. Tests like this are best done AFTER phase one is finished, so you can carry someone to record data and keep a good lookout for traffic.
 
Steve, it is interesting that your L/D was 11.3 to 11.8 over the whole speed range! Really surprising, but data is data.
 
If you transition train with Jan Bussell, he WILL pull the power to idle at 400' on one of your departures (after demonstrating the maneuver at some point in your training). Making the runway is not a problem, but overrunning it might be (landing downwind).
 
In a former (Military) life, "turnbacks" were taught and practiced on light aircraft, and in fact up to the Hawk jet. Thoughts from that teaching:
  1. It was generally only taught to instructors, not "students".
  2. It was "taught", and required to be practiced every 28days.
  3. The "aim" (not the Hawk, but including the Jet Provost) was to "land on the airfield, not necessarily the runway".
  4. The RAF lost plenty of aircraft practicing this manoeuvre - usually due it becoming a technical exercise, not an emergency manoeuvre.
  5. Every single takeoff was immediately preceded by a brief, where the speed/height requirements were reiterated, and the factors relevant to that takeoff applied e.g. crosswind (you turn into wind), surrounding fields etc., headwind, aim of the exercise (save life, land on airfield, eject if it is not looking good at 300')
Applied to an RV, and from our experience:
  1. We don't practice it enough, so would only attempt it if the area ahead was built up / water (we are both 10000hr+, airline pilots, lots of types of flying behind us).
  2. The RV, being overpowered, tends to climb quicker than it glides, so even in still air you will have a problem getting back on the airfield i.e. not past it!
  3. Are those keen to turnback really putting saving life as their #1 priority? Or hoping to save their pride and joy?
  4. Speed kills. A forced landing with a 10K tailwind on anything other than a runway is very hazardous. A rough field with a 10K headwind will probably see you walk away. 10K wind = 20K difference in touchdown IAS = +75% KE to disperse / kill you.
Unfortunately, the stats and training do not support turning back in GA... However, if you think you are "up to it", I would suggest you:
  1. Train for it.
  2. Regularly practice it.
  3. Do not consider it "on the day" unless immediately prior to lining up you briefed it, including the altimeter heights (i.e. allowing for QNH / airfield elevation), wind effects, surrounding area, airfield layout i.e. at any particualry height, you have briefed if you will turn back, which way you will turn, what you are aiming to land on.
  4. If you cannot comply with 1-3 above, do as taught i.e. land within 20degrees ahead and put the effort into as slow a landing as possible, into wind, turn off what you can, get a call out.

Andy & Ellie Hill
RV-8 G-HILZ
 
Excellent post Andy, well said, my thoughts exactly. Even crashing into trees at minimum controllable is remarkably survivable. Besides a potential loss of control the probability of a downwind crash would be a concern in a 'turnback'.

http://www.equipped.org/watertrees.htm

The secret to survival is control.
 
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Rate of Climb vs Rate of Descent

I'm not flying an RV yet, just dreaming. But I have some thoughts turning back to the airport.

In the airplane I fly, the climb rate is about the same as the descent rate at idle power best glide. Also, Vy with flaps up is about the same as best glide speed. Until I raise the flaps at 500', I'm climbing at my forward speed as about 10 kias slower than best glide speed.

Anyway, in still air, my climb profile (rate of climb and forward speed) is about the same as my power-idle descent profile (rate of descent and forward speed). So if I can turn around and point back at the runway without losing any altitude (impossible, I know), I should in theory touch down at the point where I left the runway.

Let's say I can turn around and point back losing 500'. With my climb / descent profile, I'd then be 500' feet underground at the point where I left the runway. Or, more realistically, I'm going to reach the ground a long way before I get to the point where I left the runway. Will this point be on the runway? (not likely) Will it be on the airport property? (again not likely) Will it be in the middle of the freeway I normally cross just after takeoff? (all too likely)

Let's suppose I'm flying a plane where I can climb at a rate up to twice as fast as my best glide rate of descent. It seems like it might be possible to climb at a rate that would allow me to make my turn-around and then glide down to a nice touchdown on the runway. If I climb too fast, I might overshoot the runway; climb too slow, and I come up short. Of course, the "just right" rate of climb would vary based on wind speed and direction. But it seems like there would be a best climb speed that allows a turnback to the airport based on the current conditions. And of course it depends on how long it take me to recognize the need to return and actually make the turn.

Anyway, I guess I'm asking if these thoughts make any sense. As I review these issues, I've convinced myself that in my current plane, there is no way I could ever make the airport in a turnback from a straight-out departure. If I've already turned crosswind, and am close to pattern altitude, then there might be a chance, but I'd have to practice and see.

But how about in an RV? Does anyone worry about climbing at a rate that would facilitate a turnback - not too fast and not too slow? Silly questions?
 
Just watch at your local airport....

.....
But how about in an RV? Does anyone worry about climbing at a rate that would facilitate a turnback - not too fast and not too slow? Silly questions?

...on a medium to long runway, some RVs on take-off can be at pattern altitude by the end of the runway.

Just watch the height and climb rate of various planes at the far end of the runway on take-off - try and decide which ones could do a turn-around.
 
What I did

Possible reasons for differences:
  1. One or both pilots used the VSI rather than altimeter and stop watch.........
  2. Effect of unstable air (updrafts or downdrafts) on one or both data sets.
  3. Effect of changes of wind with altitude on one or both data sets. The wind will be changing as you descend. If you go through an increasing headwind, for example, that will cause an increase in the ASI reading........
  4. Inadequate stabilisation on the test points for one or both data sets. Ideally, the altitude block would be big enough so each run lasted two minutes or more,..........

1-Used a timer and altimeter
2-There were some up/down drafts, but not very large
3-Changing wind could be a factor, I didn't pay attention to this. I did glide on the same heading and from about the same location every run. In any case, with these light airplanes it seems this would only cause a momentary change in IAS
4-I descended & stabilized for at least 500 feet before starting the clock. I think I measured from 4000' to 3000', but I would need to check my notes.

In answer to RV7AV8R:
I was surprised by the L/D grouping as well. Generally the numbers were close to expected but the flatness was not at all expected. Some of it is sloppy flying, but I think some may be the effect of the prop. This is an example of test data which needs to be validated, which is why I plan to do it again.
 
St. George, Utah

...Many airfields have the Fire Department on the field. All are relatively open with few obstructions. If I'm going to crash I would rather do it on the airfield than elsewhere...
airportview.jpg

From the Saint George City Website

I must respectfully disagree that "ALL" airports are relatively open with few obstructions. In fact many of the ones I operate from are nothing like this. Another good example that many are familiar with is Sedona, AZ. When I start thinking about it, they come one after another. I think Denver City, TX is particularly nasty around the runways.

Myself, I operate from Carlsbad, NM. This is flat desert valley country. I had never really noticed all the hazards until I started walking the airport grounds on occasion.

GoogleEarth_Image.jpg

CNM

There are places one could land, off-runway, on this airport safely, but there are many more places where one would likely hit a berm or oil well or gravel pit, not to mention Dark Canyon, there on the north side.
 
2-There were some up/down drafts, but not very large
2-Even small amounts of vertical air motion can affect the results. This type of testing usually needs to be done at altitude, or very shortly after sunrise at low altitude.
3-Changing wind could be a factor, I didn't pay attention to this. I did glide on the same heading and from about the same location every run. In any case, with these light airplanes it seems this would only cause a momentary change in IAS
3-I've done this sort of testing many times, on many different types of aircraft. Usually the wind changes continuously with altitude. There is usually a noticeable difference between the rates of descent on one of the headings as compared to the other.
 
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In a former (Military) life, "turnbacks" were taught and practiced on light aircraft, and in fact up to the Hawk jet. Thoughts from that teaching:
  1. It was generally only taught to instructors, not "students".
  2. It was "taught", and required to be practiced every 28days.
  3. The "aim" (not the Hawk, but including the Jet Provost) was to "land on the airfield, not necessarily the runway".
  4. The RAF lost plenty of aircraft practicing this manoeuvre - usually due it becoming a technical exercise, not an emergency manoeuvre.
  5. Every single takeoff was immediately preceded by a brief, where the speed/height requirements were reiterated, and the factors relevant to that takeoff applied e.g. crosswind (you turn into wind), surrounding fields etc., headwind, aim of the exercise (save life, land on airfield, eject if it is not looking good at 300')
Applied to an RV, and from our experience:
  1. We don't practice it enough, so would only attempt it if the area ahead was built up / water (we are both 10000hr+, airline pilots, lots of types of flying behind us).
  2. The RV, being overpowered, tends to climb quicker than it glides, so even in still air you will have a problem getting back on the airfield i.e. not past it!
  3. Are those keen to turnback really putting saving life as their #1 priority? Or hoping to save their pride and joy?
  4. Speed kills. A forced landing with a 10K tailwind on anything other than a runway is very hazardous. A rough field with a 10K headwind will probably see you walk away. 10K wind = 20K difference in touchdown IAS = +75% KE to disperse / kill you.
Unfortunately, the stats and training do not support turning back in GA... However, if you think you are "up to it", I would suggest you:
  1. Train for it.
  2. Regularly practice it.
  3. Do not consider it "on the day" unless immediately prior to lining up you briefed it, including the altimeter heights (i.e. allowing for QNH / airfield elevation), wind effects, surrounding area, airfield layout i.e. at any particualry height, you have briefed if you will turn back, which way you will turn, what you are aiming to land on.
  4. If you cannot comply with 1-3 above, do as taught i.e. land within 20degrees ahead and put the effort into as slow a landing as possible, into wind, turn off what you can, get a call out.

Andy & Ellie Hill
RV-8 G-HILZ

Mr & Mrs Hill have some very wise words here boys and girls......
 
So for the last couple of flights I've been practicing this turn at altitude to try and nail down the best angle of bank, G, and speed to turnback - best being the least amount of altitude lost in a 360 degree turn.

C/S prop

My procedure is:

1) fly three circles at 4000 feet to determine the wind direction at 4k

2) set up into the wind at 4k, establish a full power climb at takeoff climb speed - as close as I can get to the takeoff situation as I can.

3) Climb to 5000 - this 1000 foot climb is just to get settled.

4) At 5k chop the throttle (having first put in carb heat) change NOTHING else for a count of 2 to sort of simulate the pilot hesitation (I know it could be longer).

5) Then low rpm on the prop, drop the nose, settle into my test speed and bank angle.

6) make a 360 and note the altitude after a 360.

7) Drop back to 4000 and try a different combination.

So far racking it around at 80knts - at a bank angle that gets me close to the stall (burbling) - loses only 500 feet of altitude from the moment of power chop. higher speeds (like 90) and or slightly gentler turns did worse.

I need to try even more gentle turns at different speeds. I have a lot more runs to make.

The first attachment is an overhead view showing the 3 wind circles on the right and the 4 engine out attempts on the left. The leftmost of the 4 is the one done at 80knts.

Second attachment is a side view and the 4 simulated runs are on the left - the 80knt run being the leftmost.
 

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Idle vs No Power

Hey All,

Testing our experimentals is what this category is all about. Good on those who put the rigor into the process.

A discovery I made in my RV-7 CS MT Prop is that there is a remarkable difference between idling at full coarse pitch in a glide and pulling all the fuel out of the engine at full coarse.

A method I decided upon was to really investigate the best glide configuration with fuel cut off (which involves both prop and MAP manipulation), then find how to replicate that with the engine idling. Everybody will find their own numbers but for me I need to spin up my prop from 1100 RPM at full coarse to 1400 RPM when the engine is idling in order to replicate real glide numbers.

Once I think I have found my method and alt loss for the turn I go back and run it with zero fuel in the best glide configuration just to make sure my no power numbers are actually verified from no power testing.

The power lent from idling our engines should not be discounted whether you have a fixed or variable prop.
 
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