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  #21  
Old 04-15-2010, 05:13 PM
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olyolson olyolson is online now
 
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Default 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.........
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  #22  
Old 04-15-2010, 07:51 PM
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rvmills rvmills is offline
 
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Default 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:



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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Last edited by rvmills : 04-15-2010 at 08:00 PM.
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  #23  
Old 04-16-2010, 06:32 AM
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pierre smith pierre smith is offline
 
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Default 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,
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  #24  
Old 04-16-2010, 06:55 AM
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flytoboat flytoboat is offline
 
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Default Nice write-up, one question

Quote:
Originally Posted by rvmills View Post
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
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  #25  
Old 04-16-2010, 07:13 AM
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Brantel Brantel is offline
 
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Default

Guess I should know these terms so please edjumacate me:

Low Key = ??

High Key = ??

Quote:
Originally Posted by flytoboat View Post
PPEL = ???

Thanks
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  #26  
Old 04-16-2010, 07:14 AM
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Auburntsts Auburntsts is offline
 
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Default

I'm guessing partial power emergency landing.
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  #27  
Old 04-16-2010, 08:33 AM
David-aviator David-aviator is offline
 
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Default

Quote:
Originally Posted by rvmills View Post
.....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.
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  #28  
Old 04-16-2010, 08:46 AM
Bill Dicus Bill Dicus is offline
 
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Default 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!
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  #29  
Old 04-16-2010, 09:09 AM
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rvmills rvmills is offline
 
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Default

Quote:
Originally Posted by flytoboat View Post
PPEL = ???

Thanks
Quote:
Originally Posted by Brantel View Post
Guess I should know these terms so please edjumacate me:

Low Key = ??

High Key = ??
Quote:
Originally Posted by Auburntsts View Post
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).



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
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  #30  
Old 04-16-2010, 10:29 AM
gereed75 gereed75 is offline
 
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Default 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!!
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