Optimal landing speed

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gtmize
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Re: Optimal landing speed

Post by gtmize »

It appears the consensus is 65 to 70 kts across the numbers in a DA40

when do you pull power from say 11" on final

do you pull it all?

or leave some in through the flare / touchdown?
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Rich
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Re: Optimal landing speed

Post by Rich »

One thing you need to be able to do is adjust for conditions. We've got a nearby Flight School with lots of foreign-language students. They're based out of Redmond, so they do lots of their pattern work here in Prineville and over in Madras. (We share unicom frequency with Madras, so often the radio calls are stepping on each other.) Low-time, not fluent in English and this school, like many other these days, teaches airline-type (i.e. long final) approach paths. Departure legs in closed pattern work are also rather long for whatever reason (partly sick old 150/152 galore), so long patterns at both ends are commonplace. Often there'll be 3 of these operations going at the same time at Prineville and a couple more at Madras on the frequency. So I find I have to squeeze in when arriving back at the airport.

This often results in doing a 70-80 Kt 360 approaching or even in the pattern for spacing. Basically pattern procedures are often partially improvised leading up to turn to final.

If I have the patter to myself, it's power reduction to about 8 inches abeam the runway threshhold and half flaps right there. Plane will slow to around 75-80 and start to descend, turn to base and then go to full flaps. Normally I'm down to 65 or so at this point, unless unusually heavy. From that point it's power reductions as appropriate during the turn to final and on down final. Usually over the fence is 60 for me, again, unless I'm heavy. My plane's empty weight is easily 100 lbs. less and normally carries less fuel than most other DA40's, so a little faster for others is likely to be appropriate.

Now if I'm trying to make some especially short landing and I'm not fighting gusty wind and such, I have slowed to 50 Kt just before flare. Not much float when you do this, though, so round-out execution has less margin. Not likely to be a squeaker. This is kind of a pointless exercise at Prineville, given the positioning of the turnoffs.

And speaking of runway exits, this is something I include in picking my landing spot and touchdown speed.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Optimal landing speed

Post by DaveS1900 »

DA-40: I use all the tools available to me. I fly with my head up and outside but also have a scan inside as well. Yes, airspeed is part of my scan. Yes, I target airspeed and power settings. I have come to that process over a lot of years of flying. As noted in the thread you can fly just on the cowl position to the horizon. For me cowl position is but one of several tools I use. With students, I teach a combined method of both out and in. Visual cues outside and a scan inside.

I have predetermined power settings for each leg, 15 on downwind, 12 on base, 10 on final. Slight power adjustment for sink rate. Target speeds are 80 on downwind and base, 70 on final down to ground effect. T/O flaps abeam numbers, Full after turn on final. I don't chop the power. Its a gradual but deliberate pull off of power. No turns below 500 feet, no more than 30 deg bank in the pattern.

I go for precision, trying to make every pattern exactly the same. Every touchdown at the same place. Variation occurs with wind, airport, traffic, etc. But the game is to make adjustments to counter the variation.

That's me. You don't have to agree.
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Steve
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Re: Optimal landing speed

Post by Steve »

I fly the book speeds. So my final approach speed is calculated for my landing weight. If I ever were to land at max gross, I'd be at 71 KIAS, but usually I'm at 63-65 KIAS. In my airplane, I would have to be on fumes, with no luggage, and on a diet to fly the approach at less than 60 KIAS.

Of course, I add to those speeds for any gust component. I almost always make the 1000 foot turnoff at my home field without any difficulty...
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Lance Murray
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Re: Optimal landing speed

Post by Lance Murray »

I honestly couldn't tell you what the speed is on touchdown in a DA40. Fly the airplane and look out the window. Use the force. Learn to feel your airplane.

https://www.youtube.com/watch?time_cont ... e=emb_logo
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Re: Optimal landing speed

Post by Rich »

The 50 knots I've quoted is for short-field operation practice in non-challenging weather. I've found this works in my plane at light weights by experimenting with the envelope, since short-field landing procedure is not included in the POH. This particular speed would likely be unworkable in most later-model DA40's, but a similarly lower-than-normal approach speed would work. My typical landing weight is below the documented stall speed in the POH. Hundreds of hours and close to 1,000 landings in the same plane helps.

My normal speeds are in line with book. That said, 60 knots typically yields plenty of float, so there is lots of "banked speed".

In a well-executed landing, I'll touch down at about 40 KIAS with the stall horn going. This is also true if I flared a touch high. This is also the speed at which I find I lift off in a soft-field takeoff.

Carrying power beyond the flare may get you a smoother landing but increases the amount of runway used in the float. If enough power is carried you could use it all up.

Using nose-to-horizon reference can be a very bad habit to promulgate. In an M35 Bonanza, I've been in a stable stall with VSI pegged and the nose a good 10-15 degrees below the horizon. This was induced by a pilot I was checking out that couldn't believe it was stalled with the nose below the horizon. (He actually froze with the yolk pulled full back - whimpering "what do I do?") Often there isn't a worthwhile horizon, such as at my airport, surrounded by mountains. And at night you might have none at all, or worse, a false horizon. I never use horizon reference for pitch management in the descent portion of the pattern. It's never even occurred to me. Lacking an AOA, the best indicators I have are the AS indicator and control stick position and resistance to movement. AS is just an occasional glance after configuration transitions, such as changing flap setting, to confirm I hit my desired speed for the segment. And maybe one last glance on short final, and factoring in the likelihood of losing some airspeed approaching the surface boundary layer.

I have had the fun experience of arriving in the Phoenix area in a Tri-Pacer at night with a totally dead electrical system and a dead flashlight. No lights, inside or out, no radios, instruments invisible in the dark. No horizon visible, though bank control could be managed using the city lights (and later the runway lights as reference. Luckily this was in the days before pilot-controlled lighting, so the runway lights were on. Lots of runway at Deer Valley, so no problem there. An invisible, inaudible, straight-in arrival and approach was called for. Significant maneuvering would have been super-risky.
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Re: Optimal landing speed

Post by Colin »

I am with Lance, although for a REALLY long time I was crossing the fence at 90kts because I figured a good x-wing fighter has a LOT of airflow over the control surfaces for lots of positive control. When I started trying to get the speed down it was done as he mentions, where I felt what the plane was doing and tried to get it to set down on the 1,000 foot markers just as the wings gave up the last of their lift. After the fence, I start to look for the plane feeling mushy in the sky, and I start to hunt for the top of ground effect. Then I'm listening for the whine of the stall horn, since it is something like twenty knots early. Ride the whine down, trading firmness of control for louder whining all the way.

After 1,600 hours I was getting pretty good. Then I reset everything by getting a DA42. It's much harder to hear the stall warning over the gear horn.
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Re: Optimal landing speed

Post by jb642DA »

Colin wrote: Sun Dec 08, 2019 11:33 pm .....After 1,600 hours I was getting pretty good. Then I reset everything by getting a DA42. It's much harder to hear the stall warning over the gear horn.

....that's funny (and loud too) Colin!
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Re: Optimal landing speed

Post by Rich »

A couple more comments (sick of me yet?):

Arriving at the airport, under normal circumstances I'll slow to 90 Kt before entering the pattern. If I see someone in a slower aircraft that will precede me, it'll be slower, perhaps 80, with an early 1/2 flap setting. With someone faster behind me, and sufficient runway to waste, I'll shorten up downwind to base turn. For a low-time student this sort of flexibility is not safely available. But that isn't me. The cool things I did as part of CFI training and situations I encountered exercising the privileges thereof and great familiarity with my plane allow me to do this sort of stuff. It's not aerobatics.

Historically the recommended "correct" procedure is to use 1.3 Vso on final approach in non-gusty conditions. In my plane, at what is a somewhat higher weight than is usual for me for landing, that works out to 55 Kt. At max landing weight (2535), 64.

This can all go out the window in an instrument approach ("Keep your speed up or I'll have to cancel your approach clearance.", e.g.). I've had to come down final in the yellow to retain my spot, bleeding off all the speed in the last couple of miles. The good news is this is invariably to a plenty long runway. :D
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Optimal landing speed

Post by ZAV »

I like to keep some extra airspeed 80-90 through the pattern turns and slow down on final. The runways I’m landing on are 3000+++ ft so the subsequent float in ground effect doesn’t really matter to me. I would rather have the airspeed margin through the pattern maneuvering. The DA40 is easy to slow down.
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