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  #11  
Old 10-18-2018, 11:21 AM
krw5927 krw5927 is offline
 
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Originally Posted by airguy View Post
Pretty much exactly the same for me in my 9A. I drop 10 degrees of flaps at the FAF or just prior and it sets up nicely for the descent. Full disclosure - I'm not rated yet, my checkride has been moved twice in the last week due to really low weather, currently set for Tuesday next week.
In my fixed pitch 9A, I find I have trouble descending and slowing at the same time. The plane will do one or the other at a given moment, but not both. I'm currently exploring other methods for instrument approaches, but the one I've used the most is to set up full flaps and 70-75 kts prior to the FAF, and maintaining that configuration to minimums.

The 9A has a flaps deployment airspeed around 80 kts for anything over 10 degrees, so there's a fine line between enough drag to land after breaking out at minimums, and carrying all the drag you have throughout the whole descent. If you arrive at minimums with more than 80 kts IAS, the 9A seems to require a really long runway.

Very interested to see what other RV9 drivers do. I do agree with the OP's CFII that configuration changes inside of the FAF are best avoided if possible.
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Last edited by krw5927 : 10-18-2018 at 11:25 AM.
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  #12  
Old 10-18-2018, 11:47 AM
lr172 lr172 is offline
 
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Originally Posted by Latech15 View Post
I have been practicing a lot of approaches in my 6A as well. Mine is a fixed pitch prop, so the setup is easier for me, but I have found that I have a real hard time not getting too fast on the glide slope with only 10 degrees of flaps in. In order to stay on GS and 90 knots, I put in 20 degrees of flaps just before the faf or gs intercept. Anybody else have that issue?
That's interesting. My target RPM is 1500 for a 500 FPM descent and 90+ knots. I can do this with or without 10* of flaps, though I typically deploy 10* at GS intercept. The key is to slow down before starting the descent. If you start down at 120, you will have a hard time slowing down to 90. I usually pull the throttle to 1500 or less after the GS comes down about two or three dots from full deflection. By GS intercept I am at 90+ and drop the nose down and increase throttle to 1500 if I had dropped it lower to slow faster. At around 500' + from DA, I will pull back the throttle a bit to to get the speed down to 80-85 knots if I am above that, though I tend to naturally slow down a bit as I come down the GS. Once I am visual, I pull the nose up a bit to get my speed down to landing speed and add more flaps. At ILS minimums, I skip the extra flaps and just use extra runway (every ILS I have flown has been 5000'+ runways which is more than plenty for a no flap landing at 10 above landing speed, which I practice regularly). I feel it is safer to carry a bit of extra speed on a minimums approach. Better to land long, than get near stall speed in low vis conditions. I fly a 6, so can't comment on this method for a 9 which probably is less tolerant of extra speed.

I find that small throttle adjustments are typically necessary as I progress down the GS, likely due to changes in wind speed and/or direction.

The real challenge is when ATC asks for higher speeds. This requires time at level flight to bleed the speed, so I won't accept the request if ceilings are below 800 or so. That leaves me enough to bleed off the speed and then slip down to lose the altitude while visual.

I have a 320 with a Catto.

Larry
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Last edited by lr172 : 10-18-2018 at 12:35 PM.
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  #13  
Old 10-18-2018, 12:04 PM
moosepileit moosepileit is offline
 
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Default Flight Path Angle/velocity vector

Not to make anyone a child of the magenta line, but a scan of your EFIS vector, VVI independant, will aid in close in stability while adding close-in drag from flattening CS props and adding flap.
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  #14  
Old 10-18-2018, 05:24 PM
penguin penguin is offline
 
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Sorry, I don't fly approaches like that at all. I think your CFI is trying to prepare you for an airliner.

90kt is near the minimum sink speed for an RV, so very little power is required, meaning that if you get high it is really difficult to get down without speeding up. I fly faster, at least 100kt with 110 or 120 actually being better. Flying slightly faster makes it easier to be stable as more power is required, meaning you have more power to reduce to go down. There is no problem with slowing down to land, especially with a c/s prop. Most runways with an ILS are quite long. Breaking out at 300' will give you a mile to slow down to touch down speed. I aim for a 500' cloud base as my minimum.

I leave the flaps up until I can see something, another reason to fly fast. Most 2 seat RVs are speed unstable with the flaps down. That means it is difficult to trim out on the approach. Flying an approach with any flap makes the task much more difficult.

I would suggest to examine how your airplane works best, and not to operate how a trainee airline pilot in a PA-28 is taught. Fly at a reasonable speed with no flap.

Pete
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  #15  
Old 10-18-2018, 06:37 PM
BobTurner BobTurner is online now
 
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Quote:
Originally Posted by penguin View Post
Sorry, I don't fly approaches like that at all........I aim for a 500' cloud base as my minimum.
Pete
If you break out at 500’ agl you can safely do just about anything. Here in the US ILS or LPV minimums are typically 200’ and 1/2 mile vis. Breaking out at 200’ at 120 knots, with a fixed pitch prop, just won’t work unless you have a 10,000’ runway.
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  #16  
Old 10-18-2018, 06:47 PM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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When I was at Boeing, I spent a full year doing research on unstable approaches. After I left, I published a short paper entitled "The Myth of the Unstable Approach," and you can find that easily enough on line. What got me started was looking at a half dozen ASRS reports of unstable approaches -- all landed just fine. And a half dozen ASRS reports of bad landings all came from, you guessed it, perfectly stable approaches.

The basic thesis was that the term "unstable approach" was a vague, unhelpful generalization that did nothing for accident investigation. Sure, it's good pilot technique, but at the time it was vastly overrated as a safety initiative. In fact, the Flight Safety Foundation finally came around and now talks about go around criteria separate from unstable approaches.

So on to RVs. First disclaimer - approaches are much easier to fly with a constant speed prop than with a fixed pitch prop, and it's easier to fly a precise approach by hand than with an autopilot. Why? With the autopilot handling the pitch, all you can do is chase airspeed.

Here's what I do in my fixed pitch RV-9A at an airport with significant regional jet traffic and Gulfstreams. I fly final on the ILS or LPV at 100 knots so that I can fit in better. At 500 feet, or sometimes lower, I pull the power all the way back and start adding flaps in passing 83 knots. It's not that big a deal!! Maybe it's a big deal in other planes, but it's not in the -9A. Try it both ways in the -6A and see what your plane does. Learn to fly your own plane, not somebody's idealization of how things should be done. And to be honest, I would not have found this technique if another CFII hadn't challenged me to see what my plane would actually do... Besides, if the runway has an instrument approach, it's probably not short. And if it is short, you probably don't need to worry about faster traffic behind.

One thing that I do not have down real well is a go around on autopilot. If I'm slowed down at 200 feet and hit TOGA and full throttle, the plane stays slow and it takes forever for the RPMs and power to build up. (You should not have this problem, I suspect). I may choose to reprogram the autopilot to pitch up to three or four degrees instead of the present five. Part of my solution is that I try not to fly IFR above an overcast that's lower than a thousand so that I have options in case the engine poops out. Following that logic, I'd never fly an approach to lower than 1000 feet. However, weather has been known to change, so regardless of what I anticipate, I need to know how to do a good go around at 200 feet.

When I had my old Cessna 175, 1" of manifold pressure was good for 100 feet per minute change, if I recall correctly, or 5 mph. Go find out what the numbers are for your 6A -- it makes small corrections much easier if you know about how much you need to correct.

So, yes, I agree with your CFII in theory, but not necessarily in practice. Pushing in a few more knobs is not that big a deal if there's good reason to have them set as something other than TOGA settings, like avoiding spark plug fouling. There's nothing time critical when you make the go around decision as the high workload comes later in the missed approach.

So go try things different ways. Find out what your airplane will and won't do, and what fits your personal style. See what you learn. You might get surprised, just like I still do.
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Last edited by Ed_Wischmeyer : 10-18-2018 at 07:57 PM.
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  #17  
Old 10-19-2018, 09:48 AM
Vol88 Vol88 is offline
 
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+1 for "The myth of the unstable approach"

Ed, I took from your paper that my focused involvement in the approach, landing and rollout - including knowing what I will do to go around or go missed - is at least as important as whether I'm flying an exact airspeed or descent rate or power/prop/mixture/flap setting.

Is that a fair interpretation of your paper?
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  #18  
Old 10-19-2018, 11:14 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Quote:
Originally Posted by Vol88 View Post
+1 for "The myth of the unstable approach"

Ed, I took from your paper that my focused involvement in the approach, landing and rollout - including knowing what I will do to go around or go missed - is at least as important as whether I'm flying an exact airspeed or descent rate or power/prop/mixture/flap setting.

Is that a fair interpretation of your paper?
That's a bit of an oversimplification, but yes, basically. Glad you enjoyed the paper!
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Previously RV-4, RV-8A, AirCam, Cessna 175
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  #19  
Old 10-19-2018, 11:18 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Did two approaches today -- an LPV with nobody following, and a high speed visual approach with jet traffic following, a super-busy approach controller, and an obvious rookie in the tower.

Flew most of the visual at 120 knots, and started slowing down at roughly 400 AGL with power all the way back. Didn't have to slip it, but then, the RV-9A doesn't slip nearly as well as other planes. Everything worked out just fine, hit my touchdown point on speed, and I demonstrated a very high degree of skill that I don't really possess. (I got lucky!)

So go try it and see what *your* airplane will do.
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RV-8 (steam gauges), RV-9A at KSAV (Savannah, GA; dual screen G3X with autopilot, GTN 650)
Previously RV-4, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2018 dues paid
Retired - "They used to pay me to be good, now I'm good for nothing."
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  #20  
Old 10-19-2018, 12:04 PM
Bevan Bevan is offline
 
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It’s not just about the airplane, basic trigonometry has a role to play. Assuming the glide slope for your “stabilized” approach is 3 degrees and your expected descent rate is 500fpm, your forward ground speed would have to be 94kts. Any more or less will change your rate of descent or your glide path. I would guess this would be good for relatively poor visual conditions in an RV. I’ve practiced with 600fpm descent and 113kts ground speed with good visibility and feel this would be better to fit in with other traffic and still be able to transition to landing configuration in time to make my touch down point.

I agree that ILS approaches are generally associated with runways that are long compared to the RVs requirements.

I practice 500 and 600fpm descent rates because I use the autopilot which only has settings for even 100 increments. YMMV

Bevan
Not instrument rated.
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Last edited by Bevan : 10-19-2018 at 04:47 PM.
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