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09-07-2015, 12:06 PM
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Join Date: Mar 2005
Posts: 115
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Sim Eng Failure after T/O
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
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09-07-2015, 12:31 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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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.
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09-07-2015, 12:32 PM
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Join Date: Dec 2008
Location: Los Angeles, CA
Posts: 301
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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.
__________________
John
2016 dues paid since 2008
- High hopes fade on a warm hearth stone,
he travels the fastest who travels alone-Kipling
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09-07-2015, 12:48 PM
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Join Date: Jan 2005
Location: Ottawa, Canada
Posts: 2,357
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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.
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09-07-2015, 01:02 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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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.
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09-07-2015, 01:04 PM
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Join Date: Aug 2009
Location: Newport, RI
Posts: 705
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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.
__________________
Al Girard, Newport, RI
N339AG
RV-9
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09-07-2015, 02:04 PM
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Join Date: Nov 2010
Location: ____
Posts: 829
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[quote=BobTurner;1012240]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
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.
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09-07-2015, 02:28 PM
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Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
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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'.
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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09-07-2015, 03:22 PM
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Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
Posts: 2,645
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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.
__________________
rockwoodrv9a
Williamston MI
O-320 D2A
Awaiting DAR Inspection
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09-07-2015, 04:01 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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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.
__________________
Kahuna
6A, S8 ,
Gold Hill, NC25
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