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  #11  
Old 12-10-2018, 06:21 PM
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rv6ejguy rv6ejguy is offline
 
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Idle thrust is significantly different than no thrust, especially on a Lycoming (my engine is geared 2.2 to 1 so a 900 rpm idle is only 400 prop rpm). You'll find elevator authority considerably reduced in the flair with zero power.

My thoughts on maintaining proper glide speed ( and a bit more is better than a bit less) is because you'll be a bit busy when this event really hits you and it's easy to lose 10 knots with only a few seconds of inattention/distraction. If you start at 70 and lose 10, that gives you 60. 60 knots in an RV with full flaps puts you in the 1500+ fpm descent range which is 25+ fps. This is enough to cause serious spinal compression/ death if you can't arrest that decent rate at the flare and at 60 knots, full flaps, you won't be able to.

I've noted a number of RV accidents have killed the occupants through spinal compression when they pancaked at high vertical rates by getting well below best glide speed. The airplanes were largely intact from the post crash photos and people were puzzled as to why these folks didn't survive-broken neck or crushed spine/ severed spinal cord.

I read an interesting article a number of years back where very experienced pilots were put through forced landing scenarios in a simulator. The main aim was to see if pilots had the discipline to poke the nose down at low altitude as speed was lost. I believe something like 80-85% pulled the stick back below 100 feet as the ground rushed towards them and speed was bleeding off.

I felt the same self preservation urge and had to consciously fight it. It's counter intuitive to force the nose lower while the ground rushes up at you in those last few seconds. You have little chance to survive if you get low and slow and much less with full flap. Your options already ended there at about 200 feet AGL.

I got down to around 60 knots after doing a gentle turn at about 400 AGL to align the aircraft with the plowed furrows. The high descent rate became much more apparent at about 250 feet AGL. Fortunately flaps were at zero and I had just enough energy to arrest most of the descent rate. The G meter still registered 7 Gs from the impact and that is a heck of a wallop when it's instantaneous.

I practiced forced landings a lot and I thought I would be prepared for the real thing if it happened. Despite the practice, which was certainly helpful, I wasn't fully prepared for everything I experienced in the real event.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 426.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #12  
Old 12-10-2018, 07:25 PM
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chrispratt chrispratt is offline
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Quote:
Originally Posted by RV8JD View Post
Check out the late Joe Blank’s deadstick landing video at the Alvord Desert in Post #1:

http://www.vansairforce.com/communit...d.php?t=141918

Be sure to read Joe’s thoughts in Post #8.
I noticed that Joe used full flaps in this particular video. And in Post #8 referenced above he suggests experimenting with and without flaps. I'd be curious if Joe ever came to a conclusion as to which worked best in an RV. Sadly we can't ask him. There appears to be a difference of view in this thread regarding flaps up or down. Does anyone know?

Chris
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  #13  
Old 12-10-2018, 07:48 PM
jliltd jliltd is offline
 
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Back on topic. Over on the Glasair forum some aircraft owners with certain XP400 engines have been asked to remove them and send them back to Superior for inspection. Speculation stemming from this accident.
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  #14  
Old 12-10-2018, 08:05 PM
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For those of you who are flying a -9 (or -12), remember our numbers are different than those mentioned above.

For me, 60 knots I the fast approach speed I use when heavy. At that speed the vertical speed, with full flaps is around 650 FPM with full flaps.

Each person should practice engine out landings as often as they can. In my case, once I reduce power abeam the numbers, I try to land on my predetermined spot without touching the throttle again on every landing. I wish I could say this works out every time, but I can't.
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Last edited by N941WR : 12-10-2018 at 08:15 PM.
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  #15  
Old 12-10-2018, 08:18 PM
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Default -9 wing

The -9 Wing does a lot of things well but one thing it doesn’t do well at low airspeed is retain energy. Poof it’s gone, or something like that. The cubs and late model maules that I had been accustomed to flying always had enough energy at the flair to cushion just about any decent I could throw at it. The -9 does a ok job with airspeed but will plow right through it if too slow. I guess this is true with any wing to some degree but was an eye opener to me. Even the -6 seems to retain more energy at the flair over the -9.
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  #16  
Old 12-10-2018, 10:23 PM
jliltd jliltd is offline
 
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Here is a link to the XP-400 thread at Glasair where Superior asked to have an engine returned to them before further flight...
https://forum.glasair-owners.com/t/a...r-xp-400/33904
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  #17  
Old 12-11-2018, 12:19 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by chrispratt View Post
I noticed that Joe used full flaps in this particular video. And in Post #8 referenced above he suggests experimenting with and without flaps. I'd be curious if Joe ever came to a conclusion as to which worked best in an RV. Sadly we can't ask him. There appears to be a difference of view in this thread regarding flaps up or down. Does anyone know?

Chris
I believe there are numerous factors that would influence the flaps / no flaps decision that make it far less than just a yes or no decision for all situations.

The first factor would be what model RV are you flying?

All of the short wing RV's have plain flaps that produce a small (but measurable) reduction in stall speed.
The RV-9, 10, and 14 have very effective slotted flaps that produce a higher reduction in stall speed. My opinion is that the best plan is one that allows a touch down at the slowest speed possible. In most all situations that will likely include teh use of flaps, but particularly with an RV-9,10 or 14

My personal plan for any forced landing will be to touch down as slow as possible, fully in control, and aiming for the clearest path that I can.

In ground effect, even an RV with plain flaps gains a valuable amount of stall speed reduction so if it works with the landing approach I am making, I will be using all the flaps I can get, but will be planning to postpone deployment until as late as possible to minimize developing a high sink rate.

In my opinion, it is far more important to be super familiar with the handling of your airplane at low speed, and able to fly it via muscle memory during a tense situation, so that you can concentrate on the rapid decision making processes that you likely will have to be making because one thing I am sure of..... there is no such thing as a standardized forced landing. There will always be a need to modify and adjust the plan based on what is happening in the moment, and the plan may have to be adjusted numerous times in the process.
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  #18  
Old 12-11-2018, 06:58 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
I believe there are numerous factors that would influence the flaps / no flaps decision that make it far less than just a yes or no decision for all situations.

The first factor would be what model RV are you flying?

All of the short wing RV's have plain flaps that produce a small (but measurable) reduction in stall speed.
The RV-9, 10, and 14 have very effective slotted flaps that produce a higher reduction in stall speed. My opinion is that the best plan is one that allows a touch down at the slowest speed possible. In most all situations that will likely include teh use of flaps, but particularly with an RV-9,10 or 14

My personal plan for any forced landing will be to touch down as slow as possible, fully in control, and aiming for the clearest path that I can.

In ground effect, even an RV with plain flaps gains a valuable amount of stall speed reduction so if it works with the landing approach I am making, I will be using all the flaps I can get, but will be planning to postpone deployment until as late as possible to minimize developing a high sink rate.

In my opinion, it is far more important to be super familiar with the handling of your airplane at low speed, and able to fly it via muscle memory during a tense situation, so that you can concentrate on the rapid decision making processes that you likely will have to be making because one thing I am sure of..... there is no such thing as a standardized forced landing. There will always be a need to modify and adjust the plan based on what is happening in the moment, and the plan may have to be adjusted numerous times in the process.
I agree with most of what Scott says here. Be familiar with your aircraft in various configurations and every event will have some different circumstances requiring different action.

You might need to use full flap to get into your planned field to avoid over- running into something nasty. If you've got everything well stabilized and the field made, probably no worries about dropping flap then to reduce speed to the minimum.

My main point is to watch the ASI like a hawk, no less than every 10 seconds and be aware of the sink rate with full flap and zero thrust if you get low and slow. It simply doesn't give you many options in the last critical 10 seconds.

I think many people are so conditioned to using full flap for landing, they may not consider otherwise during a forced landing. I recall an RV10 accident a number of years ago where full flap was selected during a forced landing and the high sink rate wasn't arrested in time. The plane landed so hard that it buckled the fuselage and had to be extensively rebuilt.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 426.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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