What approach speed to use floating

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PiperCruisin

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I think my flying has gotten rusty. I'm trying to land near the numbers, but I like to hold off the plane, a Cherokee 140, so it settles on the runway and I get the nice "squeak, squeak". However, it floats a lot. So I'm a bit fast.

The POW says 85 minus 3 mph for each notch, which takes me to 76. If I use the rule of thumb of 1.3Vso, I get about 72. However, the Piper handbooks are a bit sparse. Ideally this would also factor in weight and cg. When I'm putzing around the pattern solo, the gross weight means my Vso is about 49 mph and 1.3Vso is 64. On top of that, I have Horner tips and gap seals, so maybe 1-3 mph improvement.

I figure pattern should be 1.3Vso at a 45 degree bank and final at 1.1Vso and 45 degree bank (for transition and flare). I'm just using some judgement (see table below). Thoughts and opinions?

1659474243395.png
 

Dana

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It's been years since I've flown a Cherokee, but are you coming in too fast... or too high?
 

PiperCruisin

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It's been years since I've flown a Cherokee, but are you coming in too fast... or too high?
I come in high enough to clear the power lines at the end of the runway. As far as too fast, if I fly the recommended numbers, I float a lot, if I dial it back to 70, I still float a fair amount. When I run the numbers, I can come in a fair bit slower, especially at the weights I'm typically flying at. Just nervous about it.

More curious about how people calculate the appropriate approach speed for final. I think a lot of other aircraft POH account for weight which can be up to 9 mph slower when flown light and not accounting for mods.

Anybody else do this or just use the POH numbers and wonder why it floats?
 

PiperCruisin

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Very little Cherokee experience, but it sounds fast to me. POH is likely based on gross weight and poor flying skills ?
Probably 80% of my time is in Cherokees. I'm comfortable in them, but don't push the limits much. I'm guessing the POH is dumbed down or they were just too lazy to publish more precise numbers.

Of course, the low wing adds to the desire to float. This fall I'll fly the sawtooth again to get the performance curves since the upgrades.

Maybe it's just because I like to land it like the space shuttle and do aero-braking. I hate it when I see planes land flat or on the nose.
 

TFF

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They are floaters. Coming in too fast is a sure sign of landing on the nose. On final your speed should be decaying at a perfect rate to the runway. That’s the only way not to float. Your minimum round out speed is your minimum speed. You round out and controlled settling is all you have energy for. That’s the perfect landing. If you are Vso1.2-1.3 all the way you are too fast. Safe but fast. You also want to be as flat as possible and under glide slope if you got the runway made, free of obstacles. You don’t want a big round out if possible. You are at the point where you can fly the book. It’s time to see what the plane can do.
 

BJC

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Go to altitude, fly some approaches through flair / stall at different speeds. See how much margin you have, select the one that satisfies your need to avoid stall/spin/crash/burn while minimizing float at a particular weight and density altitude, with an airspeed allowance for wind speed and wind gusts.

Repeat for each unique set of parameters.


BJC
 

TarDevil

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I flew 70 on final, bleeding off to 60 over the numbers. I never carried 70 to the runway.
In the 140, it's ready to land when power is pulled. In the Warrior and Archer I still had some speed to play with.
I added another 5 kts in the Dakota solo, maybe more with a couple souls.
 

Dan Thomas

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They are floaters. Coming in too fast is a sure sign of landing on the nose. On final your speed should be decaying at a perfect rate to the runway. That’s the only way not to float. Your minimum round out speed is your minimum speed. You round out and controlled settling is all you have energy for. That’s the perfect landing. If you are Vso1.2-1.3 all the way you are too fast.
That there. Many pilots fly the approach speed right down into ground effect. That is a technique that has shown up more and more often in the last few decades, a result of bad teaching being forwarded by CFIs and multiplied in their students.

The speeds in the picture apply to a Cirrus, not a Cherokee, but the technique is clear. Reduce the power and raise the nose when still 15 to 30 feet above the ground. The speed will fall off and the airplane will sink somewhat faster, so the nose is raised more and the speed falls further. If it's done right, you arrive at the surface with insufficient speed to float. The last bit of nose-raising is the flare. Everything up to that is the round-out, and that's the part not being taught or retained.

1659487616825.png

The stall speed is lower in ground effect, due to the diminished upflow just ahead of the wing. It reduces the AoA. Low-wing airplanes have more powerful ground effect to deal with. Float will happen, even in stubby-winged airplanes, if they're too fast.

Too much speed leads to flat landings, porpoising, wheelbarrowing, floating right off the end of the runway, blown tires, burned brakes, ballooning and stalling, and nosewheel shimmy that destroys expensive components.
 

BJC

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That there. Many pilots fly the approach speed right down into ground effect. That is a technique that has shown up more and more often in the last few decades, a result of bad teaching being forwarded by CFIs and multiplied in their students.
Yup, seems that a generation or two of CFI’s have been intimidated by the risk of a stall in the pattern, and, in response, have taught “fly it on” landings.


BJC
 

Pops

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Owned a Cherokee for 5 years and did a lot of traveling in it. Have flown almost every year and model made. Sounds like you are flying the tapered wing Cherokees. Little fast and they float. That is why I prefer the straight wing Cherokees. They tend to not float. Of all the Cherokees, I'll take the 1969 Cherokee 180 for several reasons.
 

PiperCruisin

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They are floaters. Coming in too fast is a sure sign of landing on the nose. On final your speed should be decaying at a perfect rate to the runway. That’s the only way not to float. Your minimum round out speed is your minimum speed. You round out and controlled settling is all you have energy for. That’s the perfect landing. If you are Vso1.2-1.3 all the way you are too fast. Safe but fast. You also want to be as flat as possible and under glide slope if you got the runway made, free of obstacles. You don’t want a big round out if possible. You are at the point where you can fly the book. It’s time to see what the plane can do.
I've never landed on the nose or any significant ballooning, but I can see that happen to people that try to force it on or are ham fisted. Been playing with 1.25Vso for gross weight, but will probably go down to 1.3Vso for adjusted Vso for flying weight which can be a lot different.

We always talk about Vs which is calculated for gross, but never Vs for the weight being flown. Why? That is my real question.
Owned a Cherokee for 5 years and did a lot of traveling in it. Have flown almost every year and model made. Sounds like you are flying the tapered wing Cherokees. Little fast and they float. That is why I prefer the straight wing Cherokees. They tend to not float. Of all the Cherokees, I'll take the 1969 Cherokee 180 for several reasons.
Mine is a straight wing, but has some mods which probably changed its characteristics a bit. I don't remember the one I had before floating like that. Maybe buffing the paint is the problem :)

Honestly, not super concerned about being able to land on a dime for an ultra short runway that I would not dare to takeoff from.
 

BBerson

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We always talk about Vs which is calculated for gross, but never Vs for the weight being flown. Why? That is my real question.
No, the book says “speed at contact should be varied according to conditions, both windwise and loadwise.” “contact close to stall in normal conditions”.
Practice full stall at contact to calibrate your airspeed for the load.
 
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TFF

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You never know when you need to land on a dime over a greaser. I find it much easier to grease one than a solid quality plant in a certain place. The perfect landing is both at the same time.

Put some luggage in the back. 25lbs will do wonders getting the plane to balance on the mains and make control adjustments finer.
 

djmcfall

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I am the CFI for a local flying club with a PA25-140 with 160HP. With 2 soles on board and a mid fuel load (25-40 gallons) I teach this. 85 MPH on the downwind. Normal landing with 2 notches of flaps, 80 MPH on final, then 75 MPH over the fence (very short final). Less than 72 MPH over the fence just does not leave enough energy for a solid flare. With full flaps 71-74 MPH over the fence is good. With no flaps in a high crosswind keep 80 MPH over the fence. Don’t forget to add half gust factor to your approach speeds. And finally on a truly SHORT field landing, full flaps with 70 MPH or less on short final, but don’t stall until touchdown or a couple inches off the runway. Might be other ideas out there but these numbers tend to provide good results.
 

PiperCruisin

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No, the book says “speed at contact should be varied according to conditions, both windwise and loadwise.” “contact close to stall in normal conditions”.
Practice full stall at contact to calibrate your airspeed for the load.
Speed at contact is fine. I get that. I could approach at 100 mph and still land the same because I don't force it on. I see a lot of people force it on.

I'm talking about approach speed, not touchdown. Lowering approach speed well below what the POH says. Run the numbers on your plane nW=Cl*Q*S

On another note, I like to bring power down to about 1/2 wing span in height to avoid developing a high sink rate at the last moment. See video:
 

PiperCruisin

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I am the CFI for a local flying club with a PA25-140 with 160HP. With 2 soles on board and a mid fuel load (25-40 gallons) I teach this. 85 MPH on the downwind. Normal landing with 2 notches of flaps, 80 MPH on final, then 75 MPH over the fence (very short final). Less than 72 MPH over the fence just does not leave enough energy for a solid flare. With full flaps 71-74 MPH over the fence is good. With no flaps in a high crosswind keep 80 MPH over the fence. Don’t forget to add half gust factor to your approach speeds. And finally on a truly SHORT field landing, full flaps with 70 MPH or less on short final, but don’t stall until touchdown or a couple inches off the runway. Might be other ideas out there but these numbers tend to provide good results.
Sounds like good numbers, but mine will still float a ton with short final at 70. Maybe it is just the heat off the tarmac lately.

I'm also a CFI, but don't teach. That is generally good advice. I'm also an engineer and maybe overthinking this, but the difference between Vs at light solo and gross weight can be 8-9 mph so why would one use the same approach speeds?

You would not do that in a Cessna Caravan. The approach is 75-85 depending on weight at landing.
 
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