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High Key approach in a -10..

pierre smith

Well Known Member
...I've been chomping at the bit to do this since Doug Rozendahl mentioned it on here.

I arrived from a XC this afternoon and guessed that 1000' AGL in my -10 might be close. Over the end of the runway at 100 MPH and 1000' AGL, I closed the throttle and started turning onto left downwind...man this thing sinks with the prop forward but a continuous turn and a landing with full flaps touched down just short of the 1000' marker with 4000' remaining.

I don't suppose that bringing the prop control all the way back to coarse pitch will overload the engine at idle...I'd like to try this to see how much the glide improves.

This is a maneuver I'd highly recommend all of us getting used to in the event of an engine-out situation....just more familiarity with our airplanes.

Stay tuned..

Best,
 
Pierre, I do this frequently. I try to be upwind directly over the touchdown point at about 2000' agl. I pull the throttle to idle and pull the mixture all the way back (I do keep my hand on it the whole time until short final, so that I don't forget it is out in case I need power!). I trim for about 90 knots IAS, and immediately start a 360 degree continuous turn to final. I keep the prop forward for no special reason. When I'm going through the 180 degree portion of the glide, I check position and altitude, verifying that I'm higher than half the altitude (1000 agl in this case). Also, on the 180 (downwind heading) degree point, I try to be about a half mile away from the TD point.

In my 6A, it would be a fairly tight 360 turn if started only from 1000' agl.

I've been exploring the final touchdown phase on our mile long runway. Specifically, I am keeping the flaps up all the way to TD to learn the trade-offs of a slightly (only a couple knots) higher TD speed vs much better control over just where the TD spot is. I'm sure some will think this is heresy, but if one puts in full flaps on short final, it greatly limit the range of actual TD points. With no flaps, one can float a fair ways or not in ground effect to move the TD point.

I've not concluded anything yet, as I need to make a few dozen more without flaps to get a better feel. The ability to arrest the final descent without flaps is significantly improved. With full flaps, one needs to nail the flare as well.
 
I was under the impression that in order for the prop to move from flat to coarse the engine had to be turning at least 1700 rpm to generate enough oil pressure to move the blades. I really don't know, just what I had picked up during hangar flying tales and seemed to fit since we run up to 1700 to cycle to cycle the prop prior to takeoff.
 
I was under the impression that in order for the prop to move from flat to coarse the engine had to be turning at least 1700 rpm to generate enough oil pressure to move the blades. I really don't know, just what I had picked up during hangar flying tales and seemed to fit since we run up to 1700 to cycle to cycle the prop prior to takeoff.

Somebody may correct me if I'm wrong,

But you should have a lot more than 1700 rpm if the mixture has just been pulled back and the prop is windmilling. Aircraft is still moving right along, and the governor attempts to maintain it's set rpm. It takes quite a bit to stop the prop.

L.Adamson --- RV6A
 
I don't suppose that bringing the prop control all the way back to coarse pitch will overload the engine at idle...I'd like to try this to see how much the glide improves.
I am no expert, but I can't see how it would overload the engine at idle power??
I did glide tests some time ago and found that the prop will go coarse to the extent that it has a significant effect on the sink rate even with the mixture at idle cutoff.

At 70 kts with the mixture at idle cut-off (dead engine) and prop control full in:
Sink rate on the VSI 1,200 fpm
Oil pressure 55 psi
RPM 1350

At 70 kts with the mixture at idle cut-off (dead engine) and the prop control fully out (coarse):
Sink rate on the VSI 800 fpm
Oil pressure 50 psi
RPM 900

I also found that the sink rate with the engine dead and the prop control set at full coarse is very similar to the sink rate with the prop stopped.

Fin
9A, 0-320, 9:1 CR, Hartzell CS prop, MT govenor.
 
I don't suppose that bringing the prop control all the way back to coarse pitch will overload the engine at idle.

I have been thinking about this some more since my earlier post (#5). Lets say your normal idle when on the ground is 600 rpm. I think you will find that in flight your full coarse idle rpm would be well above 600 rpm, so if anything there would be less load on the engine compared to normal idle on the ground?

Fin
 
Negative, Rick...

I was under the impression that in order for the prop to move from flat to coarse the engine had to be turning at least 1700 rpm to generate enough oil pressure to move the blades. I really don't know, just what I had picked up during hangar flying tales and seemed to fit since we run up to 1700 to cycle to cycle the prop prior to takeoff.

...it'll go to coarse pitch as long as there's oil pressure and I've seen it do it at idle.

Alex, when I practise this maneuver, in my head, it's a forced landing and I've long ago made up my mind that I'll have full flaps by touchdown to greatly lessen forward impact forces...so for me, full flaps.

Best,
 
...it'll go to coarse pitch as long as there's oil pressure and I've seen it do it at idle.

Alex, when I practise this maneuver, in my head, it's a forced landing and I've long ago made up my mind that I'll have full flaps by touchdown to greatly lessen forward impact forces...so for me, full flaps.

Best,

Pierre, it the "greatly reduce impact forces" that I'm not so sure about. The vertical component cannot be ignored, and that is what is less under our control with full flaps. If the last 20 feet of descent rate is found to be too much, it is tough without power and with full flaps to arrest it. Especially if the "runway" is an undulating field. Or a diminishing headwind is in play. Additional factors are (at least my) inability to accurately judge the last 20 feet of altitude in a non-runway situation.

As one who buzzes fields at 6 feet for a living, you may not think about this for the rest of us runway type of guys.:eek:

I need to do a lot more tests with and without flaps and record actual ground speeds at TD. I am willing to add a few (and I don't think it is much more than that) knots TD speed to greatly increase my ability to extend the TD point if necessary, as well as dodging a cow or whatever.
 
Yeah, I do buzz at 6' for a living...

...but I meant forward impact forces....the slower the better. It may well be a ditch or the trees in a short field. My-10 has around a 57 MPH stall at light weight and that is a really slow landing for the size of the airplane,

Best,
 
F=MA and E= 1/2 mv squared. The slower the better.

Pierre, the idea is that the Hi key/lo key pattern should be a comfortable glide, with plenty of room for adjustment - adjusting AOB primarily. We always used a bit more than a standard rate turn and a "wingtip" distance at low key. A wingtip distance was defined as rolling wings level and the intended point of landing should be visible on a line extended from the eyeballs , through the wingtip, to the intended point of landing. Obiviouslly this will vary with aircraft type but it is about 3 - 4000' abeam. Use a runway length to judge.

It sounds like 1000' AGL is a bit low to fly the pattern as designed. A standard rate turn will give you a 360 degree turn in two minutes. At 1000 fpm descent, that would require 2000' AGL. Using abit more than standard rate would require maybe about 8-900' per 180 degrees of turn. That is about what is taught in the military as the right AOB for the pattern. You can steepen it if low, extend it if high.

Flaps "when the field is made". That generally equate to about 150 - 200 feet on very short final. Flaps down and flair as necessary. You really have to hold the nose down to maintain AS on final and you are comitted to land when and where you flare. Yes a bit uncomfortable and a bit unforgiving of judgement errors but SPEED KILLS!!!
 
Thanks, Gary...but.....

....don't you think that a wider gliding pattern makes it more difficult to judge your descent path and touchdown point?

In the event of a real engine failure, I'd use whatever bank angle is necessary to get the job done....standard rate turn or no,

Best,
 
Pierre, Yes and no. The idea is that it is a standard pattern, flown the same way each time, so that once you intercept the pattern (hopefully by adjusting your glide into Hi key) you now have known parameters to fly to get you down at your intended point of landing.

Those parameters would never change in a perfect, no wind situation. In real life, you will have to adjust - because you hit Hi key a bit high, or low, or the wind is blowing hard, or whatever. But the beauty is those adjustments are made in a logical way against known aircraft performance.

Let's say you hit high key 300' high - you can slip a bit during the turn to hit low key right on. If you slipped too much and hit low key 150' low, you will increase you AOB a bit to tighten the pattern, or if necessary hold flap extension until 50' AGL. Again, all measured adjustments to hit standard checkpoints around the pattern. Once you intersect the pattern, it is back to a known standard flight path, that if flown in the standard way, will get you into the field.

Certainly, when it comes right down to it, your final statement is correct, your gonna do what you have to do to make the field.
 
Idle Mixture?

AlexPetersonI pull the throttle to idle and pull the mixture all the way back (I do keep my hand on it the whole time until short final said:
Why pull the mixture to idle? Seems like it's a setup for an uncomfortable situation if there's any distractions. You are asking for trouble if you don't get the mixture back to rich on a go around. I know it's good to discuss different ideas on the ground but what's the rational for the idle mixture? I'm not the most experienced RV driver so perhaps I'm missing something here.
 
Why pull the mixture to idle? Seems like it's a setup for an uncomfortable situation if there's any distractions. You are asking for trouble if you don't get the mixture back to rich on a go around. I know it's good to discuss different ideas on the ground but what's the rational for the idle mixture? I'm not the most experienced RV driver so perhaps I'm missing something here.

Emergency landing practice in itself creates a higher risk situation for that flight than not doing it at all. However, it will greatly reduce risk if an actual engine failure occurs. If you aren't comfortable pulling the mixture, don't do it. It affects glide, but not by a whole lot.

I pull the mixture back for two reasons - one, it removes all power, and two, it prevents a bunch of after firing in the exhaust pipes (FI engines tend to do this). My hand stays on the mixture until short final, then mixture full rich, hand back on throttle. No big deal.
 
Why pull the mixture to idle? Seems like it's a setup for an uncomfortable situation if there's any distractions. You are asking for trouble if you don't get the mixture back to rich on a go around. I know it's good to discuss different ideas on the ground but what's the rational for the idle mixture? I'm not the most experienced RV driver so perhaps I'm missing something here.
There may be a significant difference in glide performance between engine at idle, and engine not running but prop windmilling. Doing practice with the engine idling will have you well prepared for the day when the throttle cable breaks and the engine is still running, but stuck at idle. But that is not the failure case that most people are worried about. If you are more worried about being ready to handle engine failure, then someday you should find out how the aircraft glides with the mixture at OFF. You obviously should pick the right time and place to do this testing with mixture OFF, but you really ought to be mentally prepared to handle an engine failure on every flight.
 
There may be a significant difference in glide performance between engine at idle, and engine not running but prop windmilling. Doing practice with the engine idling will have you well prepared for the day when the throttle cable breaks and the engine is still running, but stuck at idle. But that is not the failure case that most people are worried about. If you are more worried about being ready to handle engine failure, then someday you should find out how the aircraft glides with the mixture at OFF. You obviously should pick the right time and place to do this testing with mixture OFF, but you really ought to be mentally prepared to handle an engine failure on every flight.

Being mentally prepared to handle an engine failure on every flight is a given, Kevin, as you well know in your business. As power is pushed up for take off, if it isn't on your mind you should not be doing it.

The thing that gets pilots in trouble more than anything else is not expecting an engine failure or if it does happen, not doing the right thing. Sometimes the totally unexpected happens like Olie's Viggen pitching up when the engine failed. He instinctively rolled the machine into a modified split S and pulled out just before it hit some trees. How do you practice something like that? Olie is alive because his brain was plugged in that day.

So how do we keep our brain plugged in? The problem I have with practicing scenarios is that when things go wrong for real, they seldom fit what has been practiced. Does that mean you won't be prepared when it happens? Not necessarily.

Good preparation is wrapped up in a mental exercise as you are flying along. Is that field attainable? What is the surface wind right now? Wow, look at all those power lines. That golf course would work. Man, this is a dumb route, nothing but houses, etc, etc, hope the engine keeps purring until they are gone. This type of thinking is an absolute must in a single engine airplane. In the multi engine world, its all about dealing with the failed engine and pressing on. Here it is where do I crash. We fly over areas every day that provide no good place to land, that's the calculated risk of what we do. Many airports are surrounded with homes or businesses and some guys here live in the mountains.

Ok, so is it good idea to practice gliding without power? Statistically, it is not. The feds decided long ago pulling an engine on a check ride, whether it be a single or twin causes more grief than it is worth. Practicing it can be just as questionable. But if it feels good, I guess it is ok. I know for a fact having landed twice without power, you instinctively fly the airplane whether the engine is running or not. Your adrenaline will get you there and you really won't notice anything different except there is less noise. In one case it was about 45 seconds to ground contact and all that mattered was don't stall the airplane. In the other it was from 10,000 feet, no thought if high key or low key, just knew it was too high so did another 360 in tight figuring to put it down some where near the selected spot and it all worked out. As it turned out, it was on the numbers at the airport in Auburn, Alabama.

I practiced a high key approach in the RV last week with a 20 knot breeze. I would have crashed short of the runway due to extending the flaps too soon going into the headwind. That approach was in the bag but the wind queered it. I learned something - like don't extend flaps until the field is really made. :)
 
....don't you think that a wider gliding pattern makes it more difficult to judge your descent path and touchdown point?

In the event of a real engine failure, I'd use whatever bank angle is necessary to get the job done....standard rate turn or no,

Best,

Pierre,

At first blush, a 1000' hi key seems a bit low...but not having been there, I sure can't say it is. What angle of bank did it take to make it work? I'm pretty sure that in my clipped-wing machine it'd be tough to make that work without really wrapping it up, but your 10 likely glides much better. I'm going to go play some and see what feels good, and will report back.

I think Gary said it well...as you practice it, I'd work to establish hi key/low key altitudes that allow a fairly comfortable angle of bank and a consistent pattern size and track as the baseline. Done well, it won't take up a lot of real estate, nor will it be a radical maneuver at all, but quite smooth and predictable...actually kinda fun (to practice...the real deal would take the fun out of it for sure...but even then, if practiced, it'd be familiar territory).

By comfortable angle of bank, I don't mean one that takes you well away from the field (I understand your concern there) but rather one that allows some margin for shallowing or steepening the turn to correct the flight path for wind, without having to really wrap it up to make the field. If your hi key is so low that it takes 45 degrees AOB to make it work, then you don't have much to work with if you have a howling x-wind that blows you away from the field in the turn, or a really big headwind on final. I agree with you that, in a real-deal, you do what it takes to make the field, and I also know you are very comfortable with steep banks low to the ground.

A good baseline may be standard rate, or 25 deg or 30 deg. That's something we can each determine for our aircraft, as well as the altitudes that work best for hi and low key. But if you start a bit higher and find the AOB and flight path that make it to your spot consistently, you have a great pattern that will work anywhere, like on a X-C, when you may not know the real winds until you are in the pattern...it just gives you a little margin for error.

With that as a baseline, you can then try lower hi keys to see what you can do if you can't hit high key at your normal altitude. At some lower point you would likely just make the call to make the straight in, and slip it as necessary. You can also simulate coming into hi key at various angles off, or coming into low key from 180 out (on downwind), or hitting the 90 from a base entry, or straight in. The gist of that is that you can make a judgement call as to whether, with the altitude you have, you can hit a point in the pattern from any angle and make the field...and if not, you can make the early call to find a differnt landing site, and not try to stretch the glide and get in trouble.

Just some thougts...nice work testing it out, and good discussion!

Cheers,
Bob
 
Practice engine-outs

Practice engine failures are a great idea and one we should practice for sure. BUT you guys that are pulling the mixture to OFF and letting the engine quit are asking for trouble. What if the engine doesn't restart and you mess up the pattern (ie: bad wind correction/energy state etc) and plunk it in a field and do some damage (or worse)? Is it worth it to have to fix/replace your airplane? And how gonna explain that to the FAA: "Yes officer, I intentionaly shut off the engine in flight at low altitude because I'm a supremely gifted aviator and knew I could make the runway". I don't think this is a good idea to be spreading around, especially since a lot of inexperienced pilots read this forum and may have to start doing "some of that pilot shi...." because they read that it was OK to do it that way on the Forum. If you want to do it with your airplane that's your right and if you feel you need to shut off the engine for more realistic training that's your call. I've done a lot of SFOs (simulated flameouts) in the F-16 but in the RVs we don't have the option in most cases to do a "nylon approach" if we screw up the pattern (unless of course you always wear a chute). But then again, we never actually shut off the engine either.
Not trying to be a party pooper here but with 14,000+ hours I have some things in my bag of tricks to stay safe and this manuever ain't one of 'em. As Dave Domeier says (and he's a pretty smart guy) "IMHO the training experience is not worth the potential for the engine to not restart".
Food for thought........
 
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Agreed, Oly....

...throttle back and idling is close enough for me. What can be done is to pull the PROP control all the way out for coarse pitch and a greater glide. It'll go coarse even with a windmilling prop if there's oil pressure,

Best,
 
If you must practice a true engine out then do it on a 10,000 ft runway. If you can't land on a 10,000 ft runway with a dead engine I would suggest some training or another sport.
 
Practice engine-outs

Pierre has exactly the right idea. If you have a C/S prop, pull it back to coarse pitch and that will be your best glide "WHILE THE ENGINE IS STILL RUNNING". If fixed pitch then just take what you get with idle power. Low altitude pattern work is not the place to be messing around with the mixture control. The retractable gear guys say "There are those of us that have landed gear up & those that will". I don't necessarily agree with that statement but it sort of lends itself to this dicussion. Those of us with a mixture control lever that keep messing with it in the pattern are eventually going to regret it. Practice your engine outs and if you ever experience a real one: "Been there, done that, got the T-shirt & seen the movie" so you'll be well prepared.
Keep the brain plugged in.........
 
Today's PPEL practice

Pierre, gents:

Went up today and had some fun practicing some PPELs to determine where a safe pattern would be and where hi key, low key altitudes would be. I also wanted to test the glide difference with the prop control full fwd (fine pitch) and the prop pulled full aft (coarse pitch).

Quick story (sorry, is it OK if I hangar fly with ya'll a bit :)). As a new college-boy CFI, c1979 (yikes), I had an engine failure with a student in a C-150 during a final phase check for her PPL. Piston pin shattered, rod banging around the engine, and the racket was so loud I shut it down faster than you could say, !@#$%A^! We happened to be directly above a private glider field (appropriately enough), so I circled twice on the way down, and though my Navy days were still 2 years in the future, I flew what we would call a "double high key", or 720 degrees of turn to land. On the second downwind (low key), the prop stopped, and the plane became quite a glider. Stayed close to the field, slipped on base and final, landed, rolled out, and stepped out onto the ground...that's when the adrenalin kicked in the leg that hit the ground first started shakin'. The salty dog glider instructor came up, and I apologized for landing on his private strip, but said I'd had an engine failure. He just winked and said, "guess ya had no choice, now did ya son." He was cool! Then he said, "I looked up and saw ya, and turned to my student here, and said, 'that boy's prop's not turnin!'" Then he slapped me on the back and said good job. Like I said, he was cool, and my leg had stopped shakin'!

Interestingly, during the flight test today, I tested the pattern with the prop control forward, then pulled out, and it was almost as dramatic as the difference I saw with that 150 motor stopped (which is quite a sight to see, by the way!). I'll describe that more in the sequence below. First, here's an APRS grab of today's flight:

aprs15apr10.png


As I taxied out, there was a Waco biplane and a Citabria in the pattern on RWY 14, so my first takeoff was to the southeast and as I started up, both of them full-stopped and an L-39 came into the pattern on 8, so I did all the work in left traffic to RWY 8, with the wind about 130 @ 8-15. That made the wind direction sort of worst case, in that it blew me away from the field in the hi to low key portion, and then made it harder to make the field during the last 180 degrees of turn. But they weren't howling, so it was actually a good set up for testing.

The longer ovals are the climbs to hi key altitude, and the small circles are the PPEL patterns. Field elevation is 5,000', so I ran tests at 7,000 (2,000 AGL), 6,500 (1,500 AGL) with the prop fwd, and at 7K, 6.5K and 6,200 (1,200 AGL) with the prop pulled back. The 2K patterns were done at about 25 degrees angle of bank, the 1.5K patterns were between 25 and 30 degrees aob, and the one 1.2K pattern I did was about 35 deg aob, +/-. You can see the radius of turn differential in the APRS shot, with the larger circles being the higher patterns, and the tight circles being the lower patterns.

Since the runway is long, I used the fixed distance markers as my target, and used the old closed N-S runway/road as a marker to turn. Turns were flown at (well, at or near) 87 KIAS (my best glide) with flaps up until I had the field made. Rate of descent in the turns were as follows (and for reference, this is an RV-6 with an IO-540, and clipped wings...performance similar to a Rocket...depending on your model, your mileage will likely vary)

Prop fwd (fine): 1000-1500 fpm, tending to the 1500 side
Prop aft (coarse): 800-1100 fpm, tending to the 1000 range

From 2K, with the prop fwd, I hit a 1,000' low key, and the turn to final was comfortable. With the prop pulled out, I hit a 1,200' low key, the speed crept up on me and I had to slip on base and final to hit my mark, which was not that easy, because as I rolled wings level on final, she just floated and floated. I didn't test it, but if I was aiming for a short field, I would likely slip a bit more aggressively, and perhaps push the prop back fwd when I had the field made. I'll probably play with that a bit next time I practice this, and would like to hear other's thoughts on this.

With a 1500' hi key, I hit a 600-700' low key, albeit a bit closer abeam, and it was still pretty comfortable. With the prop pulled out at 1500', low key was a bit higher, about 800', and the turn to final required a little slipping...but I floated on final again.

When I did the pattern with a 1200' hi key, I had to stay pretty tight, and had to let the airspeed bleed a bit to make the runway, but held flaps till over the runway and I made it. There was not much room for error on that one.

So from this first test, I feel that if I can hit a high key between 1500' to 2,000' AGL, or a close-in low key between 1000' to 1200', I will be in the groove for the PPEL pattern. If I'm higher, I can extend the pattern a little or slip as needed. If the wind is really blowing, I'll want to be at the higher end of those ranges. If I haven't lost oil pressure and the prop will go coarse, then I may be able to hit the low end of the ranges and be confident of making the field. However, Murphy being who he is, I'm not going to count on the prop going coarse, and will aim for the higher end of the ranges if faced with the real McCoy.

It's a good exercise though, and was both fun and enlightening. I didn't play with the red knob at all...just don't have the cojones for that one. So I ran the tests at idle, and accepted a bit of after-firing (FWIW, in the normal pattern I normally use just enough throttle to keep it from popping). One interesting thing I saw, on the prop-back tests, when I pulled the throttle to idle, the popping started, and when I pulled the prop back, it stopped. Not sure why, but it did...maybe less back pressure from the windmilling prop?

Anyway, thanks for hanging in with the long post. Lemme know what you think, and what you see in your testing.

Cheers,
Bob
 
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Lots of really valuable info here....

...and thanks a lot, Bob.

The first time I taught/tried an emergency landing in a -6A (CS equipped) that the owner came down in for transition training, amazed me. I was used to a great glide in my -6A with a coarse Catto three blade but his glide was more akin to a set of car keys....really surprised me. Yep, we almost hit the fence on the landing end if it weren't for power.

You guys would be well advised to take this high key thing to heart and learn you airplane well....don't let complacency bite you,

Best,
 
Nice write-up, one question

Pierre, gents:

Went up today and had some fun practicing some PPELs to determine where a safe pattern would be and where hi key, low key altitudes would be. I also wanted to test the glide difference with the prop control full fwd (fine pitch) and the prop pulled full aft (coarse pitch).

PPEL = ???

Thanks
 
.....Anyway, thanks for hanging in with the long post. Lemme know what you think, and what you see in your testing.

Cheers,
Bob

Perhaps the best return on doing what you did is getting a visual picture of what will work and what won't in terms of making it to the selected landing spot.

I have a tough time remembering what key altitudes are - they can be so different depending on the wind. If this information is vital and the sole source of reference as to what is going on, it won't be that easy to compute when the motor conks out over unfamiliar territory. How does one know exactly the elevation of the terrain and convert it to meaningful information on the altimeter? It is one thing to practice this stuff over a known airport, quite another anywhere else.

That's why getting the visual picture of what will work is important. At least that's my take on the subject. Somehow, in time one can just sense, this will work or no it won't. Once that picture comes into focus, it works in any airplane.

I am not describing this very well, I know. Maybe it's the relationship of the visual glide angle and the touch down spot. If the spot just keeps getting bigger and is not slipping away or going under the nose, you've got the field made. That picture can be pretty accurate and can come into focus even from the down wind leg with practice.

When my first Subby conked out, I made a 270 degree turn from over the touch down spot from about 1000' and had no doubt the whole time the airplane would make it. The picture just looked good.

The other day when flaps were extended too early with a head wind, the picture changed dramatically and it was immediately clear the airplane would not make it to the runway....so that won't happen again under those circumstances.

It pays off to practice this stuff but we must hang a bit loose also as the circumstances may not be what is expected. I am inclined to keep it high and a little fast until the picture of landing spot comes into focus.
 
high key approach

Somewhat off topic, but if you find yourself without power in an airplane with CS prop, best glide is obtained with prop at low rpm (coarse pitch) and throttle wide open to diminish pumping losses. Personally I don't practice killing the engine with mixture at idle cut-off. In the Pitts S-2A with a 3-blade MT prop, normal approach I fly is a tight pattern with throttle closed on downwind opposite touchdown point, prop in high rpm (fine pitch). Stabilized in a gliding turn pulling the prop back to low rpm (coarse pitch) causes a dramatic flattening of the glide and a feeling of acceleration as though power had been applied. This is a good way to extend your glide if you're coming up a little short. The effect varies with the airframe-engine-prop combo. It's much more noticeable in the Pitts with the 3-blade MT than it was with the 2-blade Hartzell. Putting a little slip in allows for a very short approach and the possibility of extending the glide by just removing some slip. The slip also improves visibility and accuracy of the touch down. Doing a continuous 180 from the 180 key allows just enough energy for flare and a short landing. All these techniques should work with lesser effect in the -10, enhanced by great visibility!
 
PPEL = ???

Thanks

Guess I should know these terms so please edjumacate me:

Low Key = ??

High Key = ??

I'm guessing partial power emergency landing.

Sorry guys, my bad. I forgot that these terms had been discussed, not in this thread, but in the "Rocket Glider" thread (here, look at page 4 and beyond, though the entire thread is very good).

A PPEL is a Navy term that stands for "Practice Precautionary Emergency Landing". Other terms could easily apply, like "Practice Flameout Landing", "Simulated Engine Failure", or even perhaps "Stuck Throttle Approach". No biggie on the name, but the technique is to fly to a known point at a known altitude from which you can make the field. Starting from over the intended landing spot is an easy reference point, and you're over the field, so its a safe place to work from as well, as you can adjust the pattern to stay as close as needed to assure a landing in a good spot. Here's a picture from that thread, which Doug Rozendal posted (hope you don't mind the grab Doug...good to spread it around).

overheadu.jpg


Hi Key is overhead the landing spot on landing heading. Low key is 180 degrees out, abeam the intended landing spot. The turn is continuous, and adjusted for wind and rate of descent to ensure you make the field. Knowing where a good hi and low key are for your aircraft will help you get to a known spot, even if you have to enter the PPEL pattern 90 degrees off of runway heading, or at low key, or wherever. The pattern can also be "unwound" to make it a straight in...which is really the same thing as starting at a given altitude (say 2000' AGL) on a straight in, and pulling power further and further out until you determine where you can and cannot make the field. The overhead PPEL just keeps you over a good landing sight, so its a great maneuver.

The gist of it is, if you lose the motor and glide to a good landing site, but you're high, you can use this pattern to get to the touchdown point safely, without flying too far away from the field and finding that now you can't make it back. And David, good assessment...one may develop some rule-of-thumb numbers from practicing this sort of thing, and thus develop targets to hit...but its also very much about developing a feel and an eyeball for where you are and how the airplane is gliding. The numbers and the practice give some guidance and some backup to the gut feel and look. The numbers and the look go hand in hand, IMHO.

Just a technique for your bag of tricks. Sorry for the unknown terms. Not commonly used, but good to spread around among team VAF to add to the collective wisdom and keep us a bit safer!

Cheers,
Bob
 
great work Bob

I hate to keep chiming in here on a dead horse, but this is a valuable technique/skill to learn. Learn it by practicing. The beauty is that once you intersect the pattern (any part of the pattern, assuming you can), you know the field is made and you can really start to concentrate on getting the thing down exactly where you want it - maybe in that little patch or a part of the field that is best (no trees rocks etc).

Yes it is very visual as Dave said, (and yes you have to have some confidence that you know the local elevation - (not that hard) - but having a standard pattern helps your brain analyze the visual picture, and then you can make intelligent corrections.

If you are committed to the concept and value of getting to a high key, it also forces you to select a field early on in the whole engine out process, with some time to evaluate it, and maybe change if it looks bad.

When I practice, I find my thought process is -

1)clean up the cockpit (Nail A/S, trim, restart?? maydays - whatever)
2) Pick a field - pick a field, PICK A FIELD!!!
3) Compare it to other makeable options
4) Fly to the pattern

Once in the PEL pattern, anxiety is gone and the concentration is on good flying and doing positive things for survival.

Having been trained this way, I can't imagine picking a field some x miles away and attempting to glide straight to it. Yes there are visual ques you can use to help you judge whether you'll make it, but what if you get there 300" over the intended point of landing??, it'll be gone under the wing in an instant and you will be faced with taking whatever is in front of you. Or half way there you realize the wind is worse that expected and you won't make it and you just passed a field that you could have hit high key at??

Off the soapbox now. Hope it makes you think about how you'll deal with a stressful situation and more importantly, hope it saves someone's bacon!!
 
...but its also very much about developing a feel and an eyeball for where you are and how the airplane is gliding.

You are absolutely right Bob! Glider pilots are actually trained to develop this "feel and eyeball" perspective when the flight instructor covers the altimeter and requires that the student fly a safe pattern and landing solely based on their visual reference. Safely demonstrating this skill use to be a requirement for passing the glider-rating check ride (got mine in 1976, so this may have since changed), which means that most pilots can develop this skill set with a modicum of practice.

General observation - As others have pointed out the glide performance of airplanes that have lost power is not the same as when the power is simply pulled back to idle. In order to develop the correct visual skills/references I believe that its necessary to practice power off landing procedures with the aircraft configured to accurately simulate the REAL power off glide performance. IMO Doug R's recommendation to accomplish this in the Rocket Glider thread was a very good one. He suggested first going to 5000 agl above your airport of choice at high key position and pull the mixture to cutoff, then make your 360 degree turn noting the actual altitude at which you reach low key and the landing spot (you then have lots of altitude left over for restarting, or dealing with things if you can't). Once you know how much altitude you will really loose without power you can configure the plane with flaps and power to simulate the real power-out glide performance. Then practice actual high-low key maneuvers at lower altitudes in the "simulated" configuration.

I believe that practicing and developing these visual reference skills can make a real difference in affecting a safer outcome during an engine-out emergency. But folks may be lead down the path of false security unless they practice and develop these skills in a manner that accurately depicts what REALLY HAPPENS when things unexpectedly go quiet...

Maybe only worth 1.5 cents...
 
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Couple more thoughts, hopefully to add to the usefulness of the maneuver:

Say you have not had a full-blown engine failure, but the motor is shakin' or noisy or otherwise sick and not puttin' out...or you're just worried its just a matter of time before it goes quiet. This pattern is a great way to stay at a safe altitude, and not give up any altitude you may wish you had back (should the motor quit) until you have the field made.

Its really meant to be another arrow in your quiver, rather than the way to do it, nor is it suggested that you fly around to hit a high key in every situation. Given you could be anywhere in relation to a suitable landing site when an engine quits, depending on your position and altitude, you may still end up entering the landing pattern on downwind (perhaps hit a low key), you may end up lined up on a nice base, or you could be straight in. If straight in, and too low for a hi key entry but too high for a normal straight in, then s-turns and slipping may be the way to go. Those judgement calls are where practice develops the scan for the key altitudes and the eyeball for the look and feel of how its going. But there's certainly no one right answer.

Gary, I agree with your thoughts on not trying to stretch the glide. Another tid-bit from my C-150 engine-out was that we had just completed ground reference maneuvers and a simulated engine failure (go figure!), and were climbing out to do stalls and slow-flight. The engine just sounded loud, and NQR (not quite right), so we climbed for altitude before turning for home plate (on the other side of the SF Bay). It let go at 2500', right over Fremont Sky Sailing (the no-longer-there glider field). In the first 180 deg of turn, I saw Fremont (also no longer there) airport ahead, and considered going for it, since it was not private, and it was all paved, versus the 1/2 paved, 1/2 dirt of Sky Sailing. A little voice popped up in my 400 hour, new CFI head and said, "your instructor taught you, you can land anywhere in an emergency". Good instructor, good words of wisdom, and I'm glad I didn't try to stretch it! Of course the same instructor (then boss) had a very funny look on his face when my student and I jumped out of the 172 we hitched a ride in back to Palo Alto! :eek:

Sorry for the continued hangar flying...just fun to do. Hope the discussion is helpful!

Cheers,
Bob
 
I was up playing with the -8 this evening, and did a best-glide 360 with the engine at idle - simulating the turn from High-Key to touchdown. Lost about 1800' total in the manuever - felt I had a little reserve. Probably could do it with 1500'

(Far better than the "Heavy Glider" - High Key is about 50,000' - Low key about FL350....)
 
On my aircraft I have found that I can closely simulate the real dead engine, full coarse sink rate by leaving the mixture rich (engine producing power), the throttle at idle and the prop to full coarse then in 1 1/4 turns.

Fin
9A
 
On my aircraft I have found that I can closely simulate the real dead engine, full coarse sink rate by leaving the mixture rich (engine producing power), the throttle at idle and the prop to full coarse then in 1 1/4 turns.

Fin
9A

Interesting Fin...sounds pretty logical. Will have to try it as well...thanks!

I was up playing with the -8 this evening, and did a best-glide 360 with the engine at idle - simulating the turn from High-Key to touchdown. Lost about 1800' total in the manuever - felt I had a little reserve. Probably could do it with 1500'

Sounds like a pretty good ball park for a 3, 4, 6, 7, or 8 & maybe a 10. Rockets perhaps a bit higher (1800-2000), and a 9 (maybe 10) perhaps a bit lower...mostly due to wing differences. I want to be careful not to overgeneralize...I haven't flown them all (yet!) and nothing like testing to see what works for each pilot/airplane combo, for sure. And weight and winds will have an impact too. Good place to start from during practice though.

(Far better than the "Heavy Glider" - High Key is about 50,000' - Low key about FL350....)

Can I try one of those...just one...that's it...I've been really good this year! :D

I know, keep dreamin'...perhaps if you can afford the gas to go up (I can't!), they might let you fly it on the way down! ;)

Cheers,
Bob
 
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Oh - one additional piece of RV-8 data (O-360, carbed, Hartzell C/S Blended Airfoil....). In a steady-state glide at 95 knots, with the throttle at idle, the difference in sink rate between prop full forward and full aft is about 150 fpm. I got a sink rate with the prop full forward of 1150 fpm, and with it full aft of about 1000 fpm, wings level.

Paul
 
Coarse pitch saved the landing today...

....after I decided to try a Low key approach at 800 AGL from downwind, abeam the threshold. The wind was blowing around 20 MPH, on my tail, on downwind, so I though about what was about to happen. Man, you get far down quickly so I turned in and lowered about half flaps and seemed to be crawling to the runway on final, so coarse pitch real quick, it felt like I added power! Never added more flaps and barely made it to the numbers, but good practise and an education on tail/headwinds.

Best,
 
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