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06-14-2008, 10:33 AM
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Join Date: Jan 2005
Location: Ottawa, Canada
Posts: 2,357
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Quote:
Originally Posted by Steve Brown
I checked 60 degrees and it leaves more margin for glide. The turn takes 12.4 seconds and altitude lost in turn decreases to 273 feet. This increases the margin at 500 AGL to 1300+ glide feet and makes it "possible" down to 317 AGL.
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If you increase the bank angle in a stablized turn, but keep the same speed, the angle of attack will vary, which will change the lift/drag ratio (and hence the glide ratio). And, as you noted, the margin to stall will decrease, which increases the risk of stall, spin, crash, burn, die.
I'd be very suspicious of any calculated turn back performance that wasn't validated by actual flight test altitude, with the flight test including representative time delay for pilot reaction, and mixture at ICO to remove idle thrust from the equation. Of course this test should be done within easy gliding range of a suitable airfield. There is a chance this test will terminate in an actual engine-out landing, but anyone who thinks they have what it takes to perform a low altitude turn-back manoeuvre should be fully capable of handling an engine-out from altitude.
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06-14-2008, 08:12 PM
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Join Date: Oct 2007
Location: Alviso, CA
Posts: 405
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It can be done
Today I had my wife with me so I tried this from a few thousand feet (that's my story and I'm sticking to it). My airspeed control was good, bank angle control not so good. Coordination not so good.
Still I made the full turn and was lined up on the "runway" after loosing only 400'
I would say there is a lot of room for improvement, but unlikely I will achieve the theoretical number of 335 feet.
Also, I didn't allow for reaction time.
This was strictly a test to see if the airplane can be turned around with respectable altitude loss. It can.
More practice and testing needed.
__________________
Steve Brown
N598SD - RV9A second owner
O-320, 9:1 pistons, Catto 3 blade
KRHV - Reid Hillview airport, San Jose, CA
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07-18-2008, 07:40 PM
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Join Date: Nov 2005
Posts: 358
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Just when you all thought it was safe to look in the safety column again.......
I have a "new" story on this subject that is too important not to share.
I had a Rocket owner come for an initial checkout. This was a multi-thousand hour pilot with lots of T/W time, and he took to the Rocket like a duck to water. We flew about 4 flights and on the last morning we sat down and had about an hour long chat about preparing for the first flight on his new airplane.
I talked about how important it is to know the terrain around the airport. (strange airport, builder assist) I talked about how many airplanes have small problems on first flights and how people focus on the small problem instead of flying the airplane and get hurt. But mostly we talked about how it is imperative that the pilot be mentally prepared to sacrifice the airplane to save his skin if he had a problem. This included the Don't turn back sermon.
The head was moving in the correct direction and he was listening and I thought he understood the concepts so we finished up and climbed in the airplane for his last flight with me.
At 500 feet AGL I pulled the throttle and guess what? He turned back hard. I was watching the airspeed very closely and fueled by what I had read in this thread, I thought I would just sit back see what happened. I was cocky and i did not think he could get me in over my head.
He was flying smoothly and frankly I thought he had a chance of pulling it off when in the blink of an eye, at about 150 degrees of turn in a 75 degree bank at 85 kias and 350 feet off the ground. The bottom wing stalled and we were instantly at 135 degrees of bank. The deceleration was smooth but quick and he pulled right through the buffet. The EVO has much better stall warning than the RV wing airplanes we got only a burble before the bottom wing unhooked. I don't know if we would have survived in an airplane with RV wing. It has a much cleaner break.
I unloaded the airplane, cobbed the power and rolled out and we recovered at around 200 feet. I was prepared, and was spring loaded to react, but I was also surprised. It did not feel like we were pulling that many Gs and the nose was waaayyyyy below the horizon..
The trainee was caught totally off guard and we agreed, he would have killed himself if he had been alone.
Good judgement comes from experience and experience comes from bad judgement....... As a result of his bad judgement to turn back, and my bad judgement to let him, both he and I had an experience, we both now have better judgement.
Unfortunately, no one else will have that experience with me because I will stop the manuver much sooner, and everyone else will have to take my word for it.
In 30 years and thousands of hours it was one of the closest I have came to buying the farm....... I don't ever need to see that manuver again......... You think I was militant about don't turn back before, you ain't seen nothin' yet.
Yes it can be done, but this guy was a very sharp pilot and he **** near killed both of us.
Don't turn back!
Doug R
Henceforth, if anybody turns more than 90 degrees off runway heading, it will be "I have the airplane."
Last edited by B25Flyer : 07-18-2008 at 08:30 PM.
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07-18-2008, 09:02 PM
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Join Date: Feb 2005
Location: Huskerland, USA
Posts: 5,862
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Doug R, What is amazing to me is you were expecting it and ready to react. Us Sunday warriors wouldn't stand a chance trying to figure out what we forgot to look at on take off. Straight ahead for me.
Thanks,  ............ I was just about ready to go to bed, but now after reading your story I won't be able to sleep for an hour or two. 
__________________
RV-7 : In the hangar
RV-10 : In the hangar
RV-12 : Built and sold
RV-44 : 4 place helicopter on order.
Last edited by Geico266 : 07-19-2008 at 03:38 PM.
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07-19-2008, 12:57 AM
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Join Date: Feb 2005
Location: LSGY
Posts: 3,198
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wow
Quote:
Originally Posted by B25Flyer
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I have a "new" story on this subject that is too important not to share.
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Wow - the hairs on the back of my neck stood up on end when I read this story. Although I've always been trained to land straight ahead, and brief this before every takeoff, reinforcement like this never hurts.
Thanks for sharing it, Doug.
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07-19-2008, 05:31 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Yep....thanks
...for the reminder, Doug. Kindly check your PM's.
Regards,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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07-19-2008, 07:53 PM
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Join Date: Dec 2006
Location: Arroyo Grande, CA
Posts: 938
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Quote:
Originally Posted by Steve Brown
The differing outcomes are likely due to airspeed, bank angle, and the differences between a 7 and a 9.
My calcualted sink rate in the turn is 933 FPM. Even bringing it up to 1000 FPM will only increase the sink in the turn by 24 feet. It's within the margin of pilot error.
Also, my glide testing showed a significant increase in sink rate just from 75 kias to 80. I didn't try higher, because I was obviously past best glide already. On top of that we're flying different airplanes. The 9 will glide better than the 7.
My gut is that the plane can do it, but the pilot is going to need some practice.
I think the proof is in the pudding. I've got to go out and try to fly a return and see how it works. Rather than start at altitude, I may just start at an airport @1000-to-1200 AGL, then start working my way down as I get a feel for it.
There is no doubt a turn back can be done. The only question is with this particular plane/pilot combo, how low can it be done.
I'm not reaching any final conclusions until I give this a reality check in the airplane. I just wanted to find out if I was in the ballpark on paper first.
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Should you turn back, or continue straight ahead? Should you attempt a loop in your plane without any aerobatic training? If you have trained to do a turn back under realistic conditions, do it! If you haven't, don't! But please; try some power-off landings at your airport, or at a near-by airport with a lower pattern altitude, and find out how your plane performs. I totally disagree with the recent training that has you using 1500 rpm during the complete landing event until near touchdown. I see these pilots doing cross-country patterns in which if their engine quit on downwind near base, they would never make it to the airport!
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07-19-2008, 08:26 PM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by elippse
I totally disagree with the recent training that has you using 1500 rpm during the complete landing event until near touchdown. I see these pilots doing cross-country patterns in which if their engine quit on downwind near base, they would never make it to the airport!
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Being realistic, what has a better chance of quitting? An engine pulled back to 1500 rpm, or an engine pulled back to idle?
Off hand, and with no googling of statistics to back me up, I'd say idle.
IMO, if we're that worried about the engine quiting, then don't fly the plane to start with.
---It's just that I DO live right under the downwind to base turn of the pattern.---
L.Adamson
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07-20-2008, 11:24 AM
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Join Date: Jan 2007
Location: Bay Area California
Posts: 123
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Quote:
Originally Posted by L.Adamson
Being realistic, what has a better chance of quitting? An engine pulled back to 1500 rpm, or an engine pulled back to idle?
Off hand, and with no googling of statistics to back me up, I'd say idle.
IMO, if we're that worried about the engine quiting, then don't fly the plane to start with.
---It's just that I DO live right under the downwind to base turn of the pattern.---
L.Adamson
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I disagree, if we’re not that worried about the engine quiting, then why all the time spent talking about and practicing forced landings?
For me it’s the reason why, if I have a choice, I’ll fly a route that keeps me within gliding distance of suitable terrain and/or civilization.
It’s the reason why I’ll make my initial climb out between Vx and Vy.
It’s the reason that while in cruise, I’ll be looking for signs of the wind direction and keeping it in the back of my mind.
It’s the reason why I don’t fly over large bodies of water.
It’s the reason that while in cruise, I’ll be picking out fields and stretches of road that I could land on if I needed to.
It’s the reason that for any given maneuver (cruising, stall practice, aerobatics, approach for landing, etc.) I’ll choose an altitude that affords some options in the unlikely event of an engine failure.
Why would I do all that only to throw it out the window by flying 747 patterns at my destination?
If we’re not that worried about the engine quiting, why has this thread generated over 9,400 views?
IMO, if we're not that worried about the engine quiting, then don't fly the plane to start with.
__________________
Tom
Flying RV-4
Last edited by Low n Slow : 07-20-2008 at 11:33 AM.
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07-20-2008, 11:50 AM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by Low n Slow
If we?re not that worried about the engine quiting, why has this thread generated over 9,400 views?
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This thread is about turning back with an engine failure on takeoff. I read the NTSB reports three times a week. Over the years, I've noted that there are FAR more accidents involving engine failure at takeoff, than descending in the landing pattern. And a lot of what appears to be "turn back" accidents.
However, that's possibly because everyone is flying the pattern within landing distance; make it down safely, and it isn't reported.---
IMO, it's to each his own, when it comes to tight patterns or another block out. Same goes for never using power in a landing, to always using it. Planes are different and pilots get quite religious when it comes to their own preferences.
Other than that, I haven't flown over a large body of water in at least a week, and the mountains did seem to have a few dirt roads here and there...........seriously!
L.Adamson
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