F

Finley Atherton

Well Known Member
I am thinking of the scenario where you have had an engine failure and have successfully glided to the landing area and now need to lower some flaps, descend, flare and touchdown.

My normal (engine producing power) short field, full flap, over the fence speed is about 55 kts and I know when the throttle is pulled back the rate of descent increases dramatically so I have always thought this would be too slow with a dead engine. I decided to conducted some tests where I pulled the mixture back to idle cutoff (dead engine) at about 150 ft above the runway with full flaps at various speeds.
At 65 kts the rate of descent was scary but there was plenty of power in the elevators and wings to stop the descent and flare. At 60 kts the rate of descent was frightening and there was only just enough in the elevator and wings to flare. These flights were done solo with about 1/3 fuel and with the prop full fine. I did one dead engine landing at 60 kts with the prop full coarse which gave a much gentler rate of descent and an easy flare.

So:
Light weight, full flap, prop full fine, min speed 65 kts
Light weight, full flap, prop full coarse, min speed 60 kts (could be less but I didn't try any slower as the prop might stop and the drag would increase, possibly at a critical time in the flare).
These are minimum speeds and I would possibly add 5 kts for a safety margin plus at least another 5 kts at heavier weights.

This is for my 9A and I guess you might want to be faster in the short wing Rvs?

These flights were with full flap. In a real emergency, if possible I think I would try to avoid using a lot of flap until very near the ground (maybe 10 to 15 ft). Manual flaps would be best in this situation.

I am not suggesting others should do full flap, dead engine landings at low speed. The rate of descent can be frightening and it may ruin your day if you mess up the flare. I won't be doing any more, but it was an eye opener.:eek:

Fin
9A. 0-320, Hartzell.
 
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Well my experience

When my engine failed at ~2000 ft after departing the Chino, CA airport it was throwing oil and the prop ran away until I could get throttle back enough with both hands to get it back down below 3000 rpm. I told the tower I had a problem and turned immediately back to the airport looking for a survivable landing spot within range as I went. The engine was still turning over but tearing itself to pieces and I kept the speed at about 85 kts, made a very short approach and the engine seized on the landing roll. I never touched the flaps. I had to get out and pull it off of the runway and be towed to the hangar by an airport dump truck. It seemed right for that scenario. If my engine had seized in the air I would have done it the same way except I would have slowed for the flare and perhaps put the flaps down just before landing but I don't think I would have let it get below 65kts until I was about to touchdown and I would have played the approach to suit the place where I was going to have to terminate the flight.

Bob Axsom
 
RV-8: From advice, limited testing, experience:
  1. We use a "normal" approach speed of 70K (Full Flap)
  2. Short Field 60-65K at the flare (depends on weight) - this can need power to arrest RoD
  3. Prior each Takeoff, brief in event of engne failure, glide at 80K, minimum 75K with "Full Flap" to the flare
As you say, the short wing builds up drag quickly, and with a relatively steep descent / high RoD, you need that IAS / energy to flare and arrest RoD.

Full Flap clearly increases that - but I would not discount it. It offers a steep descent, and as such, is a useful tool to judge / more accurately achieve the touchdown point, or put another way, I reckon a successful Forced Landing in a smallish field will be more likely with Full Flap available.

Andy
RV-8 G-HILZ
 
Most People are Reluctant to Say "Mayday"

I told the tower I had a problem
Bob:
Perhaps just a little Monday morning quarterbacking, but for any engine out, I'd suggest declaring as soon as you've determined a restart isn't likely-sometimes even before. At a busy airport, none of this leaves ATC much time to clear the runways. It also avoids them having to ask "Do you wish to declare an emergency" and wasting more time. Even at an uncontrolled field, someone back-taxiing may not pay a lot of attention to "I've got a problem". While you may have to file a report (only if requested to do so), my own experience with this (twice) resulted in no such report.
Regarding use of flaps, there are very few times they should be deployed until after the field is made and obstacles cleared. Speed should be at best glide as well. As noted, even the RVs bleed off energy surprisingly fast when there's no pull from the prop. Given only two choices, I'd rather impact trees at the far end after I've lost a lot of speed than at the near end doing 60+ and sinking at 300-700 fpm.
Terry, CFI
RV-9A N323TP
 
My approach speed engine out in my fixed pitch RV-6 would be the same as it is with the engine running. I often reduce power to idle on downwind and land without touching the throttle again. I use my normal approach speed of 65 knots when I do this (standard disclaimer that airspeed systems vary).

I once killed the engine at altitude and left it off until I turned off the runway. In that case I fudged and used a 70 knot approach speed. The propeller stopped on final. With the higher speed I did float more than normal but could feel that deceleration was more rapid with the engine stopped.
 
I lost power on takeoff at about 200 ft. in my new RV7. Was able to land on a "T" runway. Best landing I ever made. I pitched over and held 80mph. Plenty of speed to catch the desent on flare. No flaps used as I recall. Even had to slip a little. My glider training helped. Problem: Fuel pump was not putting out enough for my O360 at full power and failed to turn boost on.
 
These are the things I need to know!

These are the things I need to know as I get close to riveting up the fuslesge my thoughts turn to....... soon I should be able to fly.

It helps to have the experience of others to ponder upon!



Progress= Made antenna stiffeners for my com antennas this week.
Will be priming all canoe parts next week!:)
 
" What Is Your Dead Engine Short Final Approach Speed?"
The same as a live engine one.
Why on earth would they be any different?
 
Kahuna said:
" What Is Your Dead Engine Short Final Approach Speed?"
The same as a live engine one.
Why on earth would they be any different?
Click to expand...
I think it is a valid question and my experience suggests there are some differences. With a fixed pitch prop you don't have that residual thrust and with a constant speed you don't have as much braking.

Some people land with power on and there would seem to be quite a large difference if that technique is used. I think one does need to know what speed gives enough energy for a flair with full flaps and no power and if anyone doesn't know that it seems like it would be a good experiment to do to gradually reduce approach speed and find out what does give just enough but not too much energy.
 
If I have dead engine, I would not want to get too slow as you can not get the speed back quickly.
So, my dead engine practices involves keeping the speed a tad higher then normal till I am ensured making the runway. If I have enough runway then I make a normal speed landing (around 60-65K)
 
Keep more energy

Kahuna said:
" What Is Your Dead Engine Short Final Approach Speed?"
The same as a live engine one.
Why on earth would they be any different?
Click to expand...

If you hit a big downdraft with a live engine you have the option of adding power. My power out short final speed is 85 knots.

Hans
 
Mel said:
Actually with a stopped prop, drag will decrease. With the prop windmilling, you have a drag "disk".
Click to expand...

Mel,
Remember this particular flight was done with the C/S prop in full coarse (low drag). If the prop stopped it would lose oil pressure and go full fine (high drag). What has the most drag, the prop stopped in full fine or windmilling in full coarse? Other flights I have done at altitude suggests there is not much difference but I was not about to put it to the test just above the ground.

Kahuna said:
" What Is Your Dead Engine Short Final Approach Speed?"
The same as a live engine one.
Why on earth would they be any different?
Click to expand...

Because you have a much higher rate of descent and you will need more energy to arrest the descent. Without engine power you can only get this energy from more airspeed. I am sure mother earth would win if I tried to flare at my normal 55 kt approach speed with a dead engine and full flap.

Fin
9A
 
Finley Atherton said:
Mel,
Remember this particular flight was done with the C/S prop in full coarse (low drag). If the prop stopped it would lose oil pressure and go full fine (high drag). What has the most drag, the prop stopped in full fine or windmilling in full coarse? Other flights I have done at altitude suggests there is not much difference but I was not about to put it to the test just above the ground.
Click to expand...

Several years AOPA did a video with a C-182. They did calibrated glide tests with fine pitch, coarse pitch, and with the prop stopped. The glide ratio GREATLY increased with the stopped prop.

Now this is not something you would normally do unless (1) you KNEW there was no chance of a restart (2) you had plenty of altitude and (3) you needed to go a long distance to get to the airport.
 
Mel said:
Several years AOPA did a video with a C-182. They did calibrated glide tests with fine pitch, coarse pitch, and with the prop stopped. The glide ratio GREATLY increased with the stopped prop...
Click to expand...
I tested with my fixed pitch prop windmilling versus stopped and with it stopped the glide was somewhere around 20% better. I doubt if the position of a constant speed, coarse or fine, would make any difference when the prop is stopped. If you leave it windmilling, coarse would be way better of course.
 
n5lp said:
If you leave it windmilling, coarse would be way better of course.
Click to expand...
But, most of the ones that we use in RVs go flat when the power is off and with the power off they would go flat and without enough RPM, wouldn't they stay flat/fine???:confused:

Haven't used it yet. but is can't think of a reason that we wouldn't use best glide... and the flaps would stay up until making the runway is certain.
 
MauiLvrs said:
But, most of the ones that we use in RVs go flat when the power is off and with the power off they would go flat and without enough RPM, wouldn't they stay flat/fine???:confused:

Haven't used it yet. but is can't think of a reason that we wouldn't use best glide... and the flaps would stay up until making the runway is certain.
Click to expand...
They go flat when you pull the power to idle because they try to maintain the previously set higher rpm (prop control only out a bit). Try pulling the prop control full out in flight at idle rpm (do not try it at high power) and you will most likely find that the prop will go coarse as it attempts to govern itself to the low rpm you are now setting. With a dead engine my Hartzell will go coarse and stay coarse with the prop control full out. I know it has gone coarse by the immediate reduction in the sink rate. Others have reported the same. As long as the prop is rotating there will be some oil pressure which may be enough to keep the prop coarse. Here are some numbers I recorded some time ago with a dead engine:

At 70 kts with the mixture at idle cut-off and prop control full in:
Oil pressure 55 psi
RPM 1350

At 70 kts with the mixture at idle cut-off and the prop control fully out (coarse):
Oil pressure 50 psi
RPM 900

So it seems for my prop at least, there is enough oil pressure with a dead engine to operate the prop even at 900 rpm

I agree that you would use best glide speed to make the field. My post at the start of this thread is about where you have made the field and need to set up for an approach and landing. Obviously you wouldn't want to stay at best glide speed and no flap all the way to the flare as you would be landing too fast for off-field. If you are doing the forced landing on a long runway then this could be an option.
Typically you may have allowed a safety margin in your glide and are likely to be too high when you make your off-field landing area so you have to lose some speed and height. At some stage you will need to lower the flaps either to help lose height or to set up for the slowest possible off-field touch down speed. The point I was trying to make in my first post is that once the flaps are full down and without engine power, the rate of descent increases significantly and you will most likely need extra knots up your sleeve and a mighty good tug on the stick to arrest what will be an alarming rate of descent.

This is what I have found with my C/S prop in full fine. Full coarse gives a much lower rate of descent. Also I presume the rate of descent may be not quite as dramatic with a FP prop/dead engine.

Fin
9A
 
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A coarse pitch setting in an RV-10...

.....improved the rate of descent from around 1000 FPM with the engine idling and fine pitch, to around 600 FPM in coarse pitch. I demo'd this to a gent I was giving transition training to near Atlanta.

During a practice "High key" approach (Courtesy Doug Rozendaal) to my home field, I ended up short and pulled the prop control fully out and it felt like I shifted to 'passing gear' and made the runway.

Best,
 
Drag should only change your decent rate and pitch angle.
Air speed on SHORT final approach should not be any different.
 
I finally tried some engine out practice yesterday with the prop full forward and full aft. Like Pierre said, it is like getting a push from behind when you pull the prop back. I plan to get hard data at altitude, yesterday's practice was in the pattern to landing.
 
Alex,

The numbers don't really mean too much, what you need is the ability to sense the energy state of your airplane relative to a point on the ground... This will change significantly with gross weight, especially winds aloft, whether or not you can get the prop feathered etc...

Pilots want to make an engineering exercise out of the engine out maneuver and it is an airmanship exercise just like a chandelle.... Forget the numbers, fly the airplane....

Numerous things can change the glide characteristics of your airplane. A blown cylinder might rupture the cowl and there might be drag from a piece of skin blowing in the breeze....

But if you regularly practice making spot landings, at nearly minimum speed, on the Fixed distance markers from the High Key or abeam the fixed distance markers on downwind at dead idle in various winds and configurations you will have the skill you need to hit the spot...

When the day comes when you have to stuff your dead airplane into a tiny spot, having that skill set sharp will pay huge benefits...

Good on you for practicing....

Tailwinds,
Doug Rozendaal

Spring is coming, I am certain of it!!!
 
I thought this might be a useful video for you all to contemplate. EFATO is never a simple "Do This or Do That" so we did a series of tests at 2000' and then went back to the field to see what would happen at 500AGL and then 400AGL.

This was an RV10 with two POB 440lb? And 3/4 fuel. Wind was say 5 knots.

At 500 feet we would have had to do some sideslip to get back in, at 400' we would have landed half way in.

It is something that you need to be sure of in your plane and practise, this is not just something everyone can do off the cuff.

I might add 45 degrees AOB and around 85 knots, clean, hold on the AoA alarm and pull. Be careful.

The first approach is a normal glide approach then the 500AGL turnback then the 400AGL turnback.

Video is on a mates youtube, he was flying and is one of those guys who makes it all look easy. I did some at 2000' and will do some real training later.

Enjoy.

http://www.youtube.com/watch?v=uvTUW28JnpY
 
B25Flyer said:
Alex,

The numbers don't really mean too much, what you need is the ability to sense the energy state of your airplane relative to a point on the ground... This will change significantly with gross weight, especially winds aloft, whether or not you can get the prop feathered etc...

Pilots want to make an engineering exercise out of the engine out maneuver and it is an airmanship exercise just like a chandelle.... Forget the numbers, fly the airplane....

Numerous things can change the glide characteristics of your airplane. A blown cylinder might rupture the cowl and there might be drag from a piece of skin blowing in the breeze....

But if you regularly practice making spot landings, at nearly minimum speed, on the Fixed distance markers from the High Key or abeam the fixed distance markers on downwind at dead idle in various winds and configurations you will have the skill you need to hit the spot...

When the day comes when you have to stuff your dead airplane into a tiny spot, having that skill set sharp will pay huge benefits...

Good on you for practicing....

Tailwinds,
Doug Rozendaal

Spring is coming, I am certain of it!!!
Click to expand...

Doug - it is mostly the engineer in me that is curious, not the pilot. I've always thought that maximizing glide distance is interesting (after engine failure), but not too important. What is important to me is to be on the ground where I planned, and to touch down at the minimum ground speed possible.

Regarding spring coming... drove by Mason City a week ago yesterday - ice on the roads, blizzard in the sky... saw both sides of a van with a trailer ahead of us about 6 times in rapid succession, can't believe it didn't end badly!
 
B25Flyer said:
Pilots want to make an engineering exercise out of the engine out maneuver and it is an airmanship exercise just like a chandelle.... Forget the numbers, fly the airplane....


Tailwinds,
Doug Rozendaal
Click to expand...

YEP!!

Like Kahuna says, drag and angle change, but airspeed??
 
We analyzed the difference between windmilling and stopped props in university. With the exception of a full-featuring prop (where it's best to fully feather it in all cases), stopping the prop will stretch your glide. The catch is, you have to slow down below best glide speed to stop it. In an EFATO situation, don't waste the time, just get to best glide and do what you can. If you're at altitude, by all means take the time. Extra gliding distance can't hurt, and if there is a problem with the engine, stopping it turning may save it.

A twin owner near me a few years back learned the hard way what happens when you shut the engines off once you've made the runway... Both props went to fine pitch and he ended up landing short of the field and writing off the airplane. He had a gear failure and couldn't extend the gear, and wanted to save the props by stopping the engines before touchdown...

I think an aerobatic prop is set up to go coarse in the event of engine failure... Not having flown behind a CS prop myself, I don't know why this isn't the default... It seems to make more sense in emergencies?
 
Mike S said:
YEP!!

Like Kahuna says, drag and angle change, but airspeed??
Click to expand...

My basic assertion when I started this thread some time ago is that my normal FULL FLAP, SHORT FIELD approach speed of 55 kts may not provide enough lift during the flare to arrest the increased rate of descent that will occur with a dead engine. My dead engine tests confirmed this for my aircraft at least. Whether the C/S prop was in full fine or coarse was a side issue.

Compare this to a more normal situation where you are over the fence at SHORT FIELD approach speed, FULL FLAP and at idle power. Suddenly you hit a strong downdraft and the rate of descent increases (as it does with a dead engine). Are you going to add power or continue into the flare in the belief that your normal SHORT FIELD approach speed will still give you sufficient power in the wings and elevators to arrest the increased descent?

In this case you had engine power. I stand to be corrected, but as I see it, with a dead engine, the only option you have that will give you more power in the wings and elevators during the flare to arrest the increased rate of descent will be extra airspeed (over and above normal short field approach speed).

Fin
9A
 
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Interesting thread. My numbers are for the CT and probably comparable to the -12:

Landing at an airport, 55kt and flaps 15.

Landing off-airport (random field), 40-45kt (depending on weight) and flaps 40.

Teaching glider pilots, we really emphasize that the approach speed is a minimum. Without power, if you encounter wind shear and are slow, you're hosed (sorry Louise, did it again). You can always slip the airplane to bleed off energy, even 30' AGL.

TODR
 
I lost power in my RV7 on take off at 200ft. Pitched the nose over to 80mph and did my bext landing ever on a perpindicular runway. Had no time to do anything but fly the plane as far into the crash as possible. I attribute my success to the extra runway and my glider training. It is real disconserting to see the prop sticking streight up. It should be part of your flight test to determine your best L/D and minimum sink airspeeds. Most Garmin GPS's have a glide ratio function.
 
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