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Sim Eng Failure after T/O

J

jonweisw

Well Known Member
All -

After witnessing the fatal crash of a turbocharged Cessna Stationair immediately after departure from my home field (CDW) a couple weeks ago, I decided to stop being spooked and explore how my -8 does with simulated engine failures at different altitudes following simulated departure. The crash I saw has no official NTSB analysis available yet, but it was clear to me and others that there was a significant engine problem on the climb out, followed by the crash 1/2 mile from the field while the pilot tried to turn back.

So, I took it out over a fielded area with good linear landmarks and set up at 3500' (simulated hard deck) atop a straight road. I found two roads that intersected the main road that seemed to be about 4-6000' apart, so I used the intervening segment of main road as the simulated 'runway'. I flew in an upwind direction, then idled the power while maintaining 3500' and at 60kts (rotation speed) gave it full throttle to simulate takeoff. I allowed it to climb as I would on departure to various altitudes before idling it again to simulate engine failure. I immediately pitched for best glide (in mine its 77kts, although I have an AOA indicator in my dynon and that was more reliable if kept in the yellow). Then tried to make the 180 degree turn, usually at about 30-40 degrees of bank.

I found that in my plane (and I suspect most RV's), the MINIMUM altitude that a 180 degree turn could conceivable be performed to return to the airport is around 700'. That allows for the turn, trees, and some lateral movement to re-align with the runway.

Have others found this to be the case?

Some other observations;

First, idling the power in a climb attitude necessitates a very aggressive nose-down push to get it to best glide. It was more than I would have thought.

Second, with turns greater than 40 degrees of bank, it really wants to stall and drop a wing. It was pretty pronounced actually. And once that wing goes down, the VSI is pegged down and it takes a good 2-300 feet of nose down to get good aileron control to level it out.

Is this consistent with what others have observed?

Jon Weiswasser
N898JW RV-8
 
1. As you point out, 180 degrees of turn is not enough. More like 270 is needed. If possible turn into any crosswind to minimize this.
2. Best performance will require a steeper bank, which in turn will require a higher airspeed to prevent a stall.
3. To be realistic, after you reduce power to idle, you should do nothing for 2 to 5 seconds, to allow for the real world reaction time of most pilots to a surprise like this.
 
Curious

Jon,
I am curious with your comment,
?"And once that wing goes down, the VSI is pegged down and it takes a good 2-300 feet of nose down to get good aileron control to level it out."

I am curious why the rollout seems to need additional nose down pitch.
 
Keep in mind that the best glide speed and glide ratio will be different if the engine has failed vs engine running at idle. On my aircraft, the glide ratio is about 15% worse with the engine off (prop windmilling, with prop control full aft) than it is with engine at idle (8.75:1 with engine off vs 10.1:1 with engine at idle). The speed for best glide on my aircraft is about 8 kt faster if the engine is off vs engine at idle.

Bottom line - testing with engine idle may give you a false sense of security. I recommend you fly 10 kt faster than you think you need to, to cover possible increases in best glide speed with engine failed, and see how much altitude you lose then. Add several hundred feet to whatever minimum altitude you come up with to account for differences in performance between engine at idle and engine failed.
 
Kevin, did you have the throttle full forward during the engine off test? That will help.
Keep in mind you will want an airspeed slightly slower than no-wind best glide, most of the time, e.g. taking off into some wind. Initially, while headed away from the airport, you don't want best glide because you do not want to maximize the distance travelled in that direction. As you come around to the tailwind part, best glide is lower than the no-wind number. But this only applies during the very initial, and final, segments, when you are wings level. Best performance is with a steeply banked turn, that will require higher than best glide airspeed to keep from stalling.
 
Turn back

Bob said it well. More airspeed to be safe is imperative
With this maneuver. Put the nose down to 100mph and make
A steep decending turn ASAP! 45-60 Into the wind. Making the turns late
At low airspeed is the killer. Best glide 80 is not the answer in this case, only if you where landing straight ahead.

I climb out with lower pitch and faster 100-120 mph for this reason
Not Vy or Vx.
 
BobTurner said:
Kevin, did you have the throttle full forward during the engine off test? That will help. / snip


But under stress, you would not want to push the prop fine by accident:eek:


As Kevin says, a for real Engine Out will present much more drag than a simulated engine out with idle power. Very prudent to add 10kts to your practice best glide speed.
Click to expand...
 
I've practiced this maneuver repeatedly. I do a "one Mississippi, two Mississippi" count before I act on the "engine stoppage". I do not pitch for best glide until the airplane is oriented towards the runway. Instead, I pitch down and keep the airplane >100 knots where I have 3+ available G's, which I use to execute a tight, nose down turn back to the runway. Once I'm pointed towards the runway, I bring the wings back level and work to bleed speed and get the flaps out.

My turn back number is well below 700'.
 
I have read hundreds of crash reports with many being about very experienced pilots trying the impossible turn back to the airport. That scares the **** out of me. I will never be as good of a pilot as some of the pilots that have tried but not made it

Trying to understand the reasons those pilots made what turned into the poor choice of trying to get back is my only hope. If I ever lose an engine on takeoff or any other time for that matter, saving my plane is the last thing on my mind. I may be crazy, but I believe I could put a plane down almost anywhere and survive. Once the wing drops, you die. I will be going straight ahead or at least somewhere I can see out of my windscreen. Even the expert pilots don't always make the impossible turn.
 
Kevin is correct. In my practicing engine outs, I also found that my 6 cyl 2 blade metal, as it would bump to each next compression, about 3 seconds between strokes at 90 kts, at horizontal, my stall speed was ~15kts faster. It would stall my left wing and really catch your attention. This would happen as I neared the flare and would absolutely be a scary moment. My procedure is to hit the pavement, or what ever surface I happen to be landing on, at 80kts engine out. Anything less and I risk dropping a wing and crashing when the prop hits horizontal. Would be terrible to make a controlled decent to a nice landing, only to tumble and crash at the last moment.
Every departure, at throttle up, check altitude, add 1k', that's my turn back number.
 
Safe altitude

Rock, would you risk a straight in off field landing
If you lost your engine at 1k agl? My point is turning back
May be a safer alternative if A, you practiced this manuaver and
B, you where at a min safe turn back AGL.

A nose down high airspeed (100mph min and maintained)descending steep bank turn 45-60 deg will not stall the plane. The hard part is managing all that energy after you level off the wings and having brass ones with commitment putting the nose to the ground. The key to this manuaver is to not pussy foot with airspeed
or a non aggressive bank and knowing your own personal safe AGL. I have practiced this manuaver and personally have an altitude bug set at 600' above field elev. If I don't make it
Back to the runway, at least I'll be heading back toward it with a lot of energy.
 
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BobTurner said:
Kevin, did you have the throttle full forward during the engine off test? That will help.
Keep in mind you will want an airspeed slightly slower than no-wind best glide, most of the time, e.g. taking off into some wind. Initially, while headed away from the airport, you don't want best glide because you do not want to maximize the distance travelled in that direction. As you come around to the tailwind part, best glide is lower than the no-wind number. But this only applies during the very initial, and final, segments, when you are wings level. Best performance is with a steeply banked turn, that will require higher than best glide airspeed to keep from stalling.
Click to expand...

Bob - looking at my notes from that flight, and the data recorded by my laptop, it is clear that the throttle was at idle during the engine off testing. I agree that pushing the throttle to full would increase the pumping drag on the prop, and should result in a somewhat lower windmilling rpm, and a bit less windmilling drag. I did two test points where I stopped the prop, and for those I pushed the throttle forward. Even will full throttle and prop control full aft, it took me between 80 and 110 seconds to get the prop to stop, with the airspeed on the ragged edge of the stall with full flap (I couldn't get slow enough with the flaps up to get the prop to stop turning). And the prop would start turning again if I got faster than 85 kt.

My test results, with engine off and test results with engine at idle.
 
Kahuna said:
Kevin is correct. In my practicing engine outs, I also found that my 6 cyl 2 blade metal, as it would bump to each next compression, about 3 seconds between strokes at 90 kts, at horizontal, my stall speed was ~15kts faster. It would stall my left wing and really catch your attention. This would happen as I neared the flare and would absolutely be a scary moment. My procedure is to hit the pavement, or what ever surface I happen to be landing on, at 80kts engine out. Anything less and I risk dropping a wing and crashing when the prop hits horizontal. Would be terrible to make a controlled decent to a nice landing, only to tumble and crash at the last moment.
Every departure, at throttle up, check altitude, add 1k', that's my turn back number.
Click to expand...

Should that behavior be factored into the operational procedures of a 'normal' RV? At 80 kts in my -4 with wood prop, I'd miss the threshold at the *departure* end of most runways I fly from/to. :) Stalling would never be an issue unless I decided to add a Top Gun move to the emergency procedures.

Charlie
 
Turnback

The guy from Oregon who writes a monthly column for Sport Aviation wrote an excellent article about this a couple years ago. RV8.
Sunrise Aviation at John Wayne airport teaches turnback to student pilots in Cessna 172. They have an excellent video of actual turnbacks to a simulated runway at low altitude.
Aircraft such as the Cessna 206 and 207 and the A36 Bonanza do not do well in the turnback. I tried it a couple of times in the A36 and found the performance to be horrible. Something in excess of 1200' just to do a 180, starting from normal climb speed. Piper Lance in simulated emergency landing takes 1200', gear stays up until base to final, flaps on short final. Pitts S1 will make it from 600' but the pattern has to be very tight. This is a 180 to land, not a simulated turnback.
There are many airports where one might not survive straight ahead. Lots of possible scenarios such as do you want to go in the water in cold weather.
Watching the Unlimiteds at Reno is a real education. They ALWAYS trade speed for altitude. There have only been a few off airport Unlimiteds at Reno in 50 years. Many more made the runway with no damage. Rare Bear must have been dead sticked at least 20 times over the years, maybe a lot more.
 
Turnback

My 180 Pitts on takeoff from a 3000' runway would cross the departure end at 1000' AGL in near standard conditions. The most critical decision point in this case would be after the point where a landing could be made straight ahead on the runway-from that point to the end of the runway. After 800' AGL no problem.
Years ago I watched the same pilot make prop stopped landings in Pitts S1 from a very low altitude on two consecutive days. Base leg was approximately to the middle of a 4000' runway. Base to final turn was below 100' agl and turn was completed VERY low. A lightweight Pitts is actually a very forgiving airplane as long as one does not abuse the controls.
 
I am always amazed when I see charts for emergency proceedures. They are very good at giving us guide lines but you usually can throw them out in most emergencies. They are done in controlled situations. and can not take in all the conditional changes. Winds/ Temps. Pilot experience. Fixed pitch, constant speed. One plane has 30 degree of flap max another has 45. Both RV's
Each person needs to get with an experienced pilot/ Instructor and practice.. in various configurations. Then you' have a good guess at what might be a bad outcome.

One thing most pilots do not do is take winds into consideration when they take off. Any time you attempt a turn back to an airport runway should be done into the wind so you gain the benefit of a tail wind component on the turn back.

The other item and most students and pilots will hesitate... It is a big pitch change from an 90 mph climb out on an RV to a 90 mph descend and a 50 ot 60 degree bank which is required to get an RV turned around and headed back to a runway. Ask any Short wing Piper.... about a turn around.... the RV is in the same boat except the nose down/turn has to be almost instant.

If you practice enough you will get pretty confidant in a turn back... Better yet... go get a glider rating and really practice it.... from 200 feet. You'll be a much better pilot.

Rope breaks are required training in gliders...
You can turn an RV around well less than 600 feet.. but you must practice and when you pull on to the runway... ask your self everytime where is the wind... and which way will I turn should I lose it. be prepared...Practice. there are no acrobatic pilots who live without practice and lots of it.

Here is the delima on a nice winter day....
You want to impress the folks on the ground and do a short field takeoff climb out at 80mph and your 500 feet high AGL mid way down a 5000 foot strip... and you lose the engine... which is better... go straight ahead... or turn it around...? Try it..Then lets talk about it.

If you pass the threshold for landing at 500 feet AGL... How much runway does it take you to get the plane down.... into a headwind... Try it from the other end with a 10 or 15 mph tail wind. 3000 feet will go by really quick. What does Van say about slips with full flaps. What speed works best...? 75,70,65?


We all play with our aircraft... I have seen hundreds of RV's take off and hold it near the ground then zoom u p at the end of the runway... What then?

food for thought
Smilin' Jack
 
Smilin' Jack said:
Here is the delima on a nice winter day....
You want to impress the folks on the ground and do a short field takeoff climb out at 80mph and your 500 feet high AGL mid way down a 5000 foot strip... and you lose the engine... which is better... go straight ahead... or turn it around...? Try it..Then lets talk about it.


Smilin' Jack
Click to expand...

S turn is my answer in this scenario.
 
180

N95Jf has been my steed of choice since 6/86. She has had two power failures in that time, both involving stainless steel fluid hoses "guaranteed for life": the failure that resulted in a landing on the taxiway at Lakeport (and the bar there) en route to Van's is irrelevant. Relevantly, the engine did fail at or about 600-700 ft on departure on a warm day. I was able to do the 270/90 back to the take off runway with room to spare. The reality is at least RV4s are the kindest airplanes with so much excess performance...pity the poor souls who have similar experiences in 172s! Jim Ewing was an early adopter with an early H1...his 172 crashed in a canyon in the Sierras....you can imagine the H1 mindset...married to a 172 reality....not saying that is what happened, but it certainly is a possibility. John
 
Al, thanks for responding. It was nice meeting you at AV.

If I was at 1000', I am not confident I could do the turn. I have done it in practice but with everything else going on, it would not be my first thought. Maybe with more training and flight hours, I would take the risk. I know an off field landing is probably as dangerous as the turn, but I will be in control. If I stall, it is over. In some locations, turning back may be the best option and for sure the most convenient! The accident in Jackson Hole last year by a good pilot - probably better than I will ever be, makes me think real hard about dropping the wing to make a turn.

My plane is a tool to get me places - nothing more. I have insurance. My plane is worth a few tanks of gas - my deductible. For less than I spent on a bicycle, I will put it down wherever I think I can survive the best.

agirard7a said:
Rock, would you risk a straight in off field landing
If you lost your engine at 1k agl? My point is turning back
May be a safer alternative if A, you practiced this manuaver and
B, you where at a min safe turn back AGL.
Click to expand...
 
Engine out

If the engine is not producing any power I would pick the nose up to stop the prop. I can assure you from experience that a windmilling prop or idling prop produces more drag than a still prop. While we always practice at idle, with the engine at a complete stop my aircraft was a much better glider!

If you have enough altitude to attempt a 180, I suggest a turn at 45deg and keep your airspeed up to account for the higher stall speed. What is much tougher situation to recognize is a partial loss, as when the cable for my carb heat broke and my O200 iced up just after takeoff. I made the turn back from crosswind after I finally realized I wasn't able to climb with the throttle full forward

I was curious as to the response to a wing dropping. Would not an opposite rudder input be more effective?
 
Hello Jon, Yes I agree with the fellows on putting the nose down to 90 mph and doing the 40-60 degree bank turn. In our flying club we required to demonstrate a departure on RWY34 climb 600'AGL and return and land on RWY 13 after pulling the power to idle in our 1974 Cessna 172. I didn't think it possible but the instructor does it flawlessly and he expects us to do it too. Yes its a weird flight pattern but as the group mentioned its doable. A real lifesaver to have in the brain in my opinion.

One gentleman mention about a author in Oregon and writes for Sport Aviation I think that might be referring to Laurin Paine at KSLE. Yes thats where we do the return procedure, tower and fire engines too on hand! (Rwys 13-31 & 16- 34 )

Ron in Oregon
 
This is all GREAT advice! I'm looking forward to going back out and incorporating this into the 'experiment'. A couple questions and observations to add to the discussion;

1) The concept of trading speed for altitude makes sense to me - doing everything possible to avoid a stall. However, that seems to suggest that the climb should really be a Vy climb and then some (someone stated as much). On the other hand, the turn-back decision altitude (which is what makes the decision one way or the other) is just that - an altitude. So, wouldn't it make more sense to set that altitude prior to departure and then Vx it all the way there (ie, get to that altitude as fast as possible)?

2) The accelerated stall in my -8 that goes along with the turn around is REALLY pronounced with buffeting that is NOT subtle. In addition, in order to break the stall to level the wings, you end up very much nose down (hence the VSI being pegged). I cant imagine what the natural impulse would be if this were occurring at 500': the windscreen showing nothing but terrain, etc. This might explain why SO many experienced pilots fall into this trap, and why, ultimately, it might make sense to add 20% to the turn-back-altitude to account for the shock of experiencing this maneuver at low altitude.

3) Am I to understand that my schema for practicing this should include an extra 10kts to the best glide to account for the engine running? Does this relate (in terms of the simulation) to distance travelled or aerodynamics? For distance travelled, I get it. For exceeding critical angle, I dont.

4) While we are on the subject, what is everyone's best glide? What is your turn-back altitude? Would you rely on an AOA if you have one over your airspeed?

This whole experience has reiterated the need for a very conscious and deliberate departure briefing on every flight to including turn back altitude and direction and straight ahead landing areas (to the extent that they are known).

MANY thanks to everyone who is responding and to the moderators for bumping this to front page news!

Jon
 
rv7charlie said:
Should that behavior be factored into the operational procedures of a 'normal' RV? At 80 kts in my -4 with wood prop, I'd miss the threshold at the *departure* end of most runways I fly from/to. :) Stalling would never be an issue unless I decided to add a Top Gun move to the emergency procedures.

Charlie
Click to expand...

No. The point is that if you don't do actual testing on your plane with real power off tests, starting high and learning feeling and measuring, and onto going to actual landings, you will never know or understand how your plane behaves and responds.
 
Turn

I had a very great learning experience when I got my tail wheel
Endorsement in an RV-6. I was taught this manuver by a very experienced
And reputable instructor within this community. This portion of my training was worth all the money as I never out of fear, would ever have practiced this manuver.

With two larger people and full tanks and I'm sure the instructors pucker factor,
100 mph was the target glide. Climbing out at 120, at 500 agl, the throttle was pushed to idle. Immediate focus was on air speed as I continued the climb to 100 mph then dropped the nose to maintain 100 and began to bank the plane.
The only way to pull this off at this altitude is with an aggressive 50-60 deg bank. I was assured at 100 we where safe to do this. Before I knew it we where heading back to the runway and needed to level off the wings. Deployed full flaps, maintained 80mph glide and dead sticked half way down the runway. Did this multiple times. This was fantastic skills to learn on how this is done.

I have practiced this manuaver on my own at altitude and 1k Agl. At 1k AGL, focus was needed to disburse the energy so I would not overshoot the runway.

My departure/run up checklist now includes an engine out emergency landing checklist. Set the altitude bug 600' above field elv., determine direction of turn based on wind.

I'm sure if reality struck and the prop stopped turning at 500-600 AGL, I would still look for my options for a straight in approach into an open area, however with no option for straight in, at least I will know how it's done and be somewhat prepared. It's a do it right or die manuaver. One that I hope I will never have to do.
 
In reading the thread one thing popped out in my mind. The poster was getting a accelerated stall in the simulated turn back yet had AOA installed. That indicates there is something incorrect in the AOA installation or calibration. I don't know if the dynon AOA is a derived or actual AOA but I would spend some time sorting it out.
G
 
jonweisw said:
This is all GREAT advice! I'm looking forward to going back out and incorporating this into the 'experiment'. A couple questions and observations to add to the discussion;

"1) The concept of trading speed for altitude makes sense to me - doing everything possible to avoid a stall. However, that seems to suggest that the climb should really be a Vy climb and then some (someone stated as much). On the other hand, the turn-back decision altitude (which is what makes the decision one way or the other) is just that - an altitude. So, wouldn't it make more sense to set that altitude prior to departure and then Vx it all the way there (ie, get to that altitude as fast as "

This was my questions as well. Vx or Vy was not recommended for this manuaver. If you loose an engine at Vx, or even Vy, your close to stall speed by the time you react, you have to gain airspeed loosing valuable altitude in order to turn back. If you have 100 to 120 airspeed at 500 AGL, your much better off than having 80 or 90. Sure you will reach500-600 AGL sooner, but you won't be able to safely turn the plane around by the time you put the nose back down to gain valuable airspeed.
I personally climb out between 100-120 for this reason, it also keeps my #3 cylinder a bit cooler. People die from this by lack of airspeed in the turns or by stretching it out to get back. The energy created by a 100 mph dive is good to have.
Click to expand...
 
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sailvi767 said:
In reading the thread one thing popped out in my mind. The poster was getting a accelerated stall in the simulated turn back yet had AOA installed. That indicates there is something incorrect in the AOA installation or calibration. I don't know if the dynon AOA is a derived or actual AOA but I would spend some time sorting it out.
G
Click to expand...

No -- this was in the course of trying to figure out the best combination of speed and bank angle to get it right. Wasn't using the AOA when I noticed this. Only mentioned it because it is pretty pronounced in our planes..
 
Kahuna said:
No. The point is that if you don't do actual testing on your plane with real power off tests, starting high and learning feeling and measuring, and onto going to actual landings, you will never know or understand how your plane behaves and responds.
Click to expand...

Do you actually turn your engine OFF for this???? I'm too afraid to do this....even at altitude.
 
Turn Back Considerations

One thing missing from this thread regarding the 45 - 60 degree AOB turn (I do 60): you need to be familiar with your planes handling characteristics at 60 degrees AOB while aggressively pulling g's near - not into - a stall. Be able to pull hard and know what it feels like to maintain controllability just above (pick a stall margin you're comfortable with) stall. A 45 - 60 degree AOB turn without pulling won't work.
 
jonweisw said:
No -- this was in the course of trying to figure out the best combination of speed and bank angle to get it right. Wasn't using the AOA when I noticed this. Only mentioned it because it is pretty pronounced in our planes..
Click to expand...

Ok, I was not sure in reading the original post. Do you remember if you were getting a warning from the AOA before the wing drop? If not I would still look into the calibration. Your single best tool to performing a max rate turn at high angle of bank and low airspeed should be the AOA.
G
 
Bank angle

pvalovich said:
One thing missing from this thread regarding the 45 - 60 degree AOB turn (I do 60): you need to be familiar with your planes handling characteristics at 60 degrees AOB while aggressively pulling g's near - not into - a stall. Be able to pull hard and know what it feels like to maintain controllability just above (pick a stall margin you're comfortable with) stall. A 45 - 60 degree AOB turn without pulling won't work.
Click to expand...

Ok understood. However, what I was taught is pulling up does not occur until the wings are level or close to it in this case. A decending bank turn does not exert any g factor. In no way would I pull up during the bank in this case. I'm not that good. Your seeing the runway back in view when you begin to level off the wings.
 
sailvi767 said:
Ok, I was not sure in reading the original post. Do you remember if you were getting a warning from the AOA before the wing drop? If not I would still look into the calibration. Your single best tool to performing a max rate turn at high angle of bank and low airspeed should be the AOA.
G
Click to expand...

Yeah - Im using an old Dynon (the first one actually) and the AOA doesn't display as prominently as it should. Once I started using it, it was REALLY accurate in predicting the stall. As soon as the arrow touched the red, the wing (s) would buffet.
 
jonweisw said:
The crash I saw has no official NTSB analysis available yet, but it was clear to me and others that there was a significant engine problem on the climb out, followed by the crash 1/2 mile from the field while the pilot tried to turn back.
Click to expand...

That pretty much says it all. I don't know if it's some sort of macho culture thing, but almost no-one in UK advocates or practices turning back. Find a field within 30 of the nose and do your best. Worst case, you flop in at 50kts and run into a hedge - you'll probably walk away.

I know, everyone has a field with mountains and/or trees off the end.........
 
paul330 said:
That pretty much says it all. I don't know if it's some sort of macho culture thing, but almost no-one in UK advocates or practices turning back. Find a field within 30 of the nose and do your best. Worst case, you flop in at 50kts and run into a hedge - you'll probably walk away.

I know, everyone has a field with mountains and/or trees off the end.........
Click to expand...

Absolutely the best idea given those circumstances. We don't all have that option
In congested areas of the U.S. Not Macho at all, just another tool in the box.
 
Although the RV line has great performance numbers, we as builder/pilots have to understand that this performance only occurs when the engine is running. When it is not running, it is nothing more than a poor glider. For me, turn back....Not without a couple thousand feet between me and the unforgiving earth!
 
Pitch Rate

agirard7a said:
Ok understood. However, what I was taught is pulling up does not occur until the wings are level or close to it in this case. A decending bank turn does not exert any g factor. In no way would I pull up during the bank in this case. I'm not that good. Your seeing the runway back in view when you begin to level off the wings.
Click to expand...

Don't want to get into an argument, but the above statement is incorrect in the context of optimum turn rate. Pitch rate with respect to to lift vector does not care what the attitude of the aircraft is. To get the nose around as quickly as possible and maintain control you have to lower the nose while rolling then pull. You can descend in a high angle of bank turn without pulling, but why would you do that? ACM 101.
 
pvalovich said:
Don't want to get into an argument, but the above statement is incorrect in the context of optimum turn rate. Pitch rate with respect to to lift vector does not care what the attitude of the aircraft is. To get the nose around as quickly as possible and maintain control you have to lower the nose while rolling then pull. You can descend in a high angle of bank turn without pulling, but why would you do that? ACM 101.
Click to expand...

Oh go ahead and get into an arguement; his statement is nonsense. If he wasn't pulling any "g's" the plane wouldn't turn. What is true is that you will pull fewer g's if you let the plane free fall, vertically. This is not a constant rate of descent, but falling like a rock. Lose altitude fast!
 
Glide performance

Obviously all aircraft have to rely on glide performance should an engine
quit wether it's flying straight ahead or turning around. A stopped prop will have better glide performance than a windmilling one. Yes a plane with a windmilling prop will not have the same glide performance as an idle engine prop. The bottom line is these RV's climb well and fast. When you reach 500-1,000 AGL your not far from the runway, especially in any kind of head wind. In many cases this will be accomplished before you get to the end of the runway. Once you make the initial turn around in a safe decending bank at a comfortable margin of air speed not to fall out of the sky and leveling off, the rest is up to glide performance depending on how far away you are. The times that I have done this, getting back is not the issue, it's getting down without overshooting.

Personally, this whole turn back issue I know is a heated issue with some saying don't ever try it. To me if done correctly it's a skill that may save my life one day. I'm just very greatful I was taught how to do it safely.
 
Stand corrected

pvalovich said:
Don't want to get into an argument, but the above statement is incorrect in the context of optimum turn rate. Pitch rate with respect to to lift vector does not care what the attitude of the aircraft is. To get the nose around as quickly as possible and maintain control you have to lower the nose while rolling then pull. You can descend in a high angle of bank turn without pulling, but why would you do that? ACM 101.
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Sorry stand corrected, very low g in a decending turn not a "no g".
The point being sure if your maintaing the 100 mph yes you have to pull up not to fall like a stone. So yes some G's will happen , according to my instructor, 1 g. Not to nit pick here but the point was for safety not to pull up extensively while in the bank but wait until you start to level off.
 
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agirard7a said:
Personally, this whole turn back issue I know is a heated issue with some saying don't ever try it. To me if done correctly it's a skill that may save my life one day.
Click to expand...

True statement

But I feel compelled to add to it that "done incorrectly, it will likely kill you"

A stall close to the ground is pretty much an unforgivable mistake.

If you practice the maneuver and you can perform equally well when the pressure is on, then your outcome may be good.
For all others.... a forced landing at minimum possible airspeed, even into very unfriendly terrain will probably result in not much more than a damaged airplane.... A lot better outcome than you will get if you stall.....
 
Hum-m-m no mention of the Boxed Canyon Hammerhead turn or the Fighter Pilot stand on the bottom rudder and pull into buffet. :) :)
 
Practice

I wasn't truly comfortable with the idea of the 'impossible turn' until I kept doing it in gliders while learning to transition...low level rope breaks.

I will say I agree with the following...

1. If you have not practiced it...you should not attempt it. This is akin to practicing unusual attitudes below pattern altitude. The altitude at which it can be safely conducted should be known in advance, and one should realize it will change each time one flies (weight/wind/DA blah blah)

2. This is a 'head out canopy' maneuever, if it cannot be flown with fluidity...best to land ahead.

3. If this wasn't in your mental briefing before departure, land ahead.

It's worth what you paid for it...
 
Last post

rvbuilder2002 said:
True statement

But I feel compelled to add to it that "done incorrectly, it will likely kill you"

A stall close to the ground is pretty much an unforgivable mistake.

If you practice the maneuver and you can perform equally well when the pressure is on, then your outcome may be good.
For all others.... a forced landing at minimum possible airspeed, even into very unfriendly terrain will probably result in not much more than a damaged airplane.... A lot better outcome than you will get if you stall.....
Click to expand...

Agree, it's a do it right or die senereo. I will try to make this my last post on this issue. Please, I am not advocating a turn back as a better way. I am only trying to point out that should the need ever arise that you have no choice, there is a right way to do it. Airspeed is life in this decending turn. I was taught maintaining 100 mph in a decending 50-60 degree bank then leveling off when heading back to runway, is a safe turn and an effective way to turn around quickly. At least with two Lard asses and full fuel In an RV-6. This is the do. The die is not decending enough and banking without sufficient airspeed.
 
Lots of misinformation posted...

* steep bank has nothing to do with stall speed. The misinformation is that the two are related only if you maintain altitude. Ever seen an airplane roll?
* if you do succeed in doing a 180, then what? You'll be recovering from a miserable turn to final for a downwind landing on a runway that might be occupied, depending on the airport.
* haven't tried this in an RV, but in any number of spam cans I can do a 180, starting from Vy, in 350 feet. The trick is to fly a ballistic trajectory so that your turn is done at low airspeed and you get a very high turn rate. This is more of a parlor trick than anything else because of the reason above and because this technique generates a high speed recovery.
* "standard rate" is an instrument flying yet and badmouthing to go with VFR flight
* yes, I'm rated in gliders, have taught spins and extensively sampled low speed characteristics of dozens of airplanes.

My advice?
- forget high G maneuvers at low altitude. Too easy to pull too hard. And try out the high G high alpha characteristics in advance.
- plan your engine out options before takeoff like glider pilots do on every takeoff
- if it really does happen, there's a good chance your pucker factor will be sky high. (Learned that hitting wind shear on takeoff).
- practice, practice, practice, with a CFI as necessary.
- fly within your own limitations and don't believe what you read till YOU have tried it in YOUR airplane.

Ed
CFII ATP etc
 
my opinion on this subject:
don't religiously "land straight ahead" nor attempt a hairy turn back to the runway at very low altitude. weigh risks and options in the departure briefing before getting on the runway.

a few aspects:
- expect significant difference in characteristics and performance in an actual engine failure over what our idle power tests and practicing make you believe. might also depend on the reason for the engine stoppage, mechanical problem might lock the prop vs fuel problem with windmilling.
this also applies to most low altitude turnback demos where rarely ever the engine is actually cut.

- we did quite a few simulated engine failures at vy and vx during testing. obviously some nose-down pushing is required, yet it's actually much less violent than expected on the controls. a massive pitch attitude change for sure. the reduced slipstream over the horizontal stabilizer by itself helps drop the nose, the pilot must assist a little and allow it to happen. if that is done quickly enough, there is surprisingly little speed decay, contrary to what the initial "spacebound"-attitude might leave you thinking. (at least on our RV-7A with 180hp IO-360 and hartzell constant speed 2-blade, "normal" c.g. / vx 70kts IAS / vy 85kts IAS)

- "altitude" is not simply altitude. 500ft over sea level are "worth more" aerodynamically than 500ft over an airfield at 4000ft msl. our home field is 1300ft AMSL and the difference to a sea level airfield is clearly noticeable. this doesn't only apply to the engine power part, but e.g. also to how "crisp" the airplane feels on the controls. less particles/density to support all that accelerated weight...

-my personal limits are about 400-500ft agl for a 90? degree turn (and subsequent landing/final adjustments) and 600-700ft for a 180? into the fields parallel to the home airfield/runway (tight downwind, not to the runway itself!). but at the same time, straight ahead can be very tricky depending on the local geography,

- the speed vs minimum sink curve for our rv is quite flat and wide at the top (meaning whether you fly 82, 85 or 90 doesn't make that big of a difference) and very steep on the upper and lower ends of the speed scale. (60kts drops like a rock, 120kts more like a fast cruise missile)

- we fly strictly vx to 400ft agl and then vy departures because we feel it cuts the time and window where something could go wrong while at the same time having limited options to a minimum. the "red" time window becomes very short with our performance, maybe 20s-40s or so.

- the low low altitude to runway turnback (as discussed / demonstrated by some transtion trainers) needs to be done with 45?+ degree bank, nose low, plenty of overspeed and must be flown very fluidly. definitely not recommended as a standard method unless you have a lot of practice, especially with the pressure of having to nail it because of an actual engine failure. that doesn't mean it isn't doable, from approx 600ft upwards... and for lack of better options i would certainly not refrain from trying it. there may be cases where anything behind you (not just the runway) would be better than what's ahead...

- we fly 85kts clean as best glide irrespective of weight/etc... in a turnback case definitely faster, at least temporarily

- aoa in our case is fine as a stall warner, but not really practicable to fly as primary e.g. steady in the yellow range. (too slow, nose too high, no energy reserves)

- from practice you really have to pull quite hard/move the controls far to come close to a high speed stall in the mentioned scenario. i think the low speed stall/asymmetric stall risk, especially when maneuvering is the much much greater risk. you shouldn't pull 2.5+G's or you're doing something wrong/wasting additional energy. high turn rate must not equal high g-load (you're not trying to maintain level)

and remember, YMMV your mileage may vary
 
Anyone have numbers?

From straight and level, 90 mph, engine at idle (or windmilling or off) how much altitude loss does it take to maintain this airspeed and make a 180? And what radius or off set, might that be?

I know it is going to be different for flight weight, airframe, prop, but a data point would be helpful than dramatic descriptions. I remember flying with a former F-111 pilot in his T-6. After we had done some aerobatics, he asked if I wanted to experience a "carrier landing" - I quickly said "sure" why stop now! He paralleled the runway at 300 ft, dropped to ~110kt, then did a wing over with a 180 descent to the runway and immediately squeezed her in. His airspeed was rock solid. The exact numbers are fuzzy now, but it was quite low and slow. Slow enough for a no adjustment or float on touchdown. Just having done 4 Gs in the loops, this was much lower, maybe 2ish. This sounds like a maneuver we are discussing, save the parallel offset to the runway is missing.

so, whatta ya think?
 
BillL said:
From straight and level, 90 mph, engine at idle (or windmilling or off) how much altitude loss does it take to maintain this airspeed and make a 180? And what radius or off set, might that be?


EXACTLY!!! Thats the question. Funny how its hard to get a real straight answer on this!!! At the moment, based on what I know, my personal minumum is 1100'. I couldnt tell you how much offset that is, but i could do a straight 180 with 100' to spare in 750'. The extra altitude allows the shock time, and time to re-align.

Im gonna do some more testing, this time with video which I'll post...

Jon Weiswasser, CFI
N898JW
Click to expand...
 
Two points:

First, in the "impossible turn," there is said to be a tremendous "ground rush" effect when in the steep bank descending turnback attitude ----> MANY competent pilots feel compelled to pull up....and then it's all over. You can't simulate that ground rush at 3000 feet.

Secondly, in the straight ahead (or few-degrees-left-or-right) emergency landing: airplanes that land under control, without stalling, with wings level....usually have survivors on board.
 
Practice

I went up today to practice the turn back, and I was able to make the turn easily in 500'.

Pulled to idle, Two potatoes then turn, I dump the nose and left rudder and aileron aggressively then pull the nose where you need it. I normally climb out at 87 knot and I was still at 85 knots once I was pointed at my landing aim point. with 200' to go

I have always used 700' as my turn back altitude but that is only if there is not a better choice in from of me. We have a lot of tall trees here in the NW.

Oh and to simulate ground rush I did this above a cloud deck, that does a nice job of simulating the ground.

I am not advocating what I do for anyone. However, go up to altitude and horse the plane around it will tell you when you are pushing it. My maneuver today did not create any buffet at all I was well away from any stall margins. now I did have idle RPM so that is whey I pad with the extra 200'

Cheers
 
Turn back

Last year I spent some time practicing this at altitude and then at my local airport for realistic practice. I was able to comfortably do this maneuver from 300 ft. and 110 knots. When I did it at the airport one of my airport friends heard the engine cut just after takeoff and looked up to see me maneuvering off the end of the runway. He grabbed his fire extinguisher and jumped into his pickup truck to rescue me! Guess I should have briefed him first. :)
 
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