landing with a porpoise!

Peter Ha

Peter Ha

Pre-takeoff checklist
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Hey folks,
Tell me why I porpoised here on this landing?
Had to initiate go-around because of it. :(
Some background; flying C150, this is not my home airport (KHMT), there were some winds, not overgross weight, 10deg flaps.

Skip to 13:30 mark:

 
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TLDW. skip to 13:30 to watch landing

you didn't maintain centerline and then tried to salvage it. probably too fast but I can't say for sure. then u slammed it in pretty good. that's why.
 
Often because of being fast which is probably because you were behind the plane on final, base and even perhaps downwind.
 
The only way you can start flying again is if you were too fast when you touched down. Keep pulling back and not letting it land until it runs completely out of energy and you can’t stop it from landing. I’m guessing you were more than 10 knots too fast on short final.
 
Pushing forward after bouncing perhaps??
 
It’s hard to see that well with that camera angle but it looks like you came in a bit shallow and needed speed to make runway.
porpoising is always too much energy I thought.
I Would also add if not trimmed to land you can really fight to flare enough making you a bit more nose down and bounce a lot easier.
 
I've been guilty of coming in too shallow, too fast, not paying attention, and bouncing the airplane ... all to the left of the center line! :(

If you are using earbuds you can hear what I did to correct the situation:

 
benyflyguy said:
It’s hard to see that well with that camera angle but it looks like you came in a bit shallow and needed speed to make runway.
porpoising is always too much energy I thought.
I Would also add if not trimmed to land you can really fight to flare enough making you a bit more nose down and bounce a lot easier.
Click to expand...

You just refreshed my memory!
Yes I DO remember being short to runway and giving bit throttle to make up the difference. You're good detective, ben. :)
 
Got to remember that angle of attack and airspeed are inextricably linked. If you arrive at the surface with too much speed, the airplane's attitude will be nose-low, putting the nosewheel on first and kicking the nose up. I didn't see any round-out and almost no flare, too.

Bad things can happen with too much touchdown speed. Porpoising can quickly get worse, as the first one kicks the nose up and the pilot pushes down, getting an even harder one. It goes from bad to worse. Or the airplane runs out of runway, either by floating so far down it or having no braking traction because all the speed means there's still plenty of lift. Get blown tires that way. Or the pilot flares suddenly and the airplane balloons upward and runs out of speed at 20 feet. Or the touchdown is gentle but nose-low so that the nosewheel is the only wheel on the runway. Now it's a nasty taildragger and the airplane ends up off the side somewhere, maybe busted.

Get rid of the speed before you get to the runway.

upload_2020-5-5_17-28-52.jpeg

Look at that. Get the power back and the nose up at 15 to 30 feet above the ground.

If you're going to come short, add power but raise the nose as well so you don't gain a bunch of speed.
 
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You are landing flat, meaning all three of your wheels, including the nose wheel, make contact with the runway at the same time. One the first landing, the nose gear compressed and pushed the nose back up, lifting you back into the air. And you landed flat again - probably you relaxed back pressure on the yoke to allow that to happen. And the nose gear strut compressed again, bouncing you back into the air. Most likely a good example of PIO, pilot-induced-oscillation. Your last landing was slightly better but still flat.
 
You're not going slow enough, boss
giphy.gif
 
Peter Ha said:
You just refreshed my memory!
Yes I DO remember being short to runway and giving bit throttle to make up the difference. You're good detective, ben. :)
Click to expand...
Lol speaking from experience- I’ve porpoised it before. Fly a 182 that will break quick with porpoise so I am sensitive to it
 
Grum.Man said:
60 mph on final is all you need. You have more flaps, use them
Click to expand...
Yeah 60 is a good number to aim for in a 150/152. I routinely flew 70 downwind, 65 base and 60 down final and it worked out well. Slowly reduce power to idle after crossing the fence and bleed off that energy a foot or so over the runway and you’ll land that kite like a champion!
 
You porpoised because the nosewheel is for taxiing, not for landing. Don't touch down flat. Hold it off.
 
The goal, conditions permitting, should include...

1) Landing with the yoke/stick all the way back as the mains touch. If there’s a stall warning horn it should be blaring. This will ensure landing at the lowest possible speed and with the least energy to dissipate. And no “extra speed” which invites a bounce.

2) Using maximum flaps as consistent with conditions and POH recommendations. This will lower the touch down speed.

Stipulated this does not apply to all aircraft all the time. But for the GA planes most of us fly, it’s a good place to start.

What was the motivation to use just 10° flaps?
 
Ryanb said:
Yeah 60 is a good number to aim for in a 150/152. I routinely flew 70 downwind, 65 base and 60 down final and it worked out well. Slowly reduce power to idle after crossing the fence and bleed off that energy a foot or so over the runway and you’ll land that kite like a champion!
Click to expand...

Make life easy, pull the power to idle abeam the numbers and use flaps and turns to hit your touch down point. Trim for 60 at idle on final and you will never have a problem.
 
Grum.Man said:
Make life easy, pull the power to idle abeam the numbers and use flaps and turns to hit your touch down point. Trim for 60 at idle on final and you will never have a problem.
Click to expand...

That's great idea... but I'll need time with CFI to show me before I'll attempt it. :)
 
Peter Ha said:
That's great idea... but I'll need time with CFI to show me before I'll attempt it. :)
Click to expand...

Why???o_O Did you not practice simulated engine outs to get your PPL? It’s the same thing and is really the smart way to fly all approaches at least until you get into high performance airplanes
 
If you can, go get your tailwheel endorsement... honest, itll make all your Landings Better
 
The cause of porpoising is always the same. Not flaring enough. The reason is usually not looking far enough down the runway and/or not being familiar with the correct touchdown sight picture. Excess speed on final approach combined with an impatience for flaring the necessary amount is a common scenario in which it occurs.
 
Grum.Man said:
Why???o_O Did you not practice simulated engine outs to get your PPL? It’s the same thing and is really the smart way to fly all approaches at least until you get into high performance airplanes
Click to expand...

Yes i did do emergency landing in 172 once.
Guess I'm just afraid of stalling base-to-final. :rolleyes:
 
Peter Ha said:
Hey folks,
Tell me why I porpoised here on this landing?
Click to expand...

Just as others have said,

Because either...

1. Your nose wheel hit first -or-
2. You landed flat enough that your nose wheel was still able to absorb enough energy to start the porpoising process.

Slow down
Flare to hold it off
Touch down mains first and hold the nose off until it just falls on it's own.
 
Peter... you seem like a great guy and have a talent for flying.

But, judging by some of your posts it seems as though your instructor may have been a bit weak.
Perhaps a few dual lessons with a different CFI should be in order.

Its not you per-se, but some stuff you have posted cries for more instruction.
 
I porpoised on my first solo landing, plopping down three times before it was over. Very embarrassing! I was surprised that my instructor let me continue! I immediately learned that lowering the noise during the bounce was a bad idea, and I never made that mistake again. My second landing was better, and my third one was textbook.
 
An airplane has two landing wheels. The nose wheel is for steering. Don't land on it. Keep adding back pressure on the yoke until the airplane stalls, just inches off the deck.
Tip: While parked, sit in the the cockpit and have a friend push down the tail until the nose wheel lifts off the pavement. You will be surprised how high the nose attitude is as viewed from the pilot's seat.
 
Peter Ha said:
Yes i did do emergency landing in 172 once.
Guess I'm just afraid of stalling base-to-final. :rolleyes:
Click to expand...

Power doesn't prevent the plane from stalling. Just keep your speed up, which means keeping the nose down, which means keeping your pattern reasonably close.
 
Dana said:
Power doesn't prevent the plane from stalling. Just keep your speed up, which means keeping the nose down, which means keeping your pattern reasonably close.
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^^^^that

Adjust pitch for speed, and power for altitude. Going too fast? Trim up. Descending too fast? Add some power.
 
Dana said:
Power doesn't prevent the plane from stalling. Just keep your speed up, which means keeping the nose down, which means keeping your pattern reasonably close.
Click to expand...
Or keep your angle of attack below the stall angle, as I can stall your plane nose down, easily.
 
Touched down flat and fast. You might have even touched the nose first. That how a porpoise happens, although was only kind of just a "porp". In my ground school.we spent about 4 hours talking about PIOs, Pilot Induced Oscillations, firewall damage, etc. Speed and touching down the nosewheel first are the two components. If you cross the threshold and are not on approach speed, go around.

I was guilty of this when I was learning to land. Then I read "How I learned to stop worrying and love the flare." In my case, I was "afraid" of not being able to see the runway ahead of me. Once I got over that, I now make sure that I'm blocking the runway with the cowl at least a little and for the few seconds of the flare to touchdown, maintaining distance from the upwind side of the runway to stay centered.
 
Peter Ha said:
Hey folks,
Tell me why I porpoised here on this landing?
Had to initiate go-around because of it. :(
Some background; flying C150, this is not my home airport (KHMT), there were some winds, not overgross weight, 10deg flaps.

Skip to 13:30 mark:

Click to expand...
I'm at work so I cant see the video due to internet restrictions but you said it wasn't your home airport. I wonder if you were fast and three pointed because a different runway gives a different sight picture than your used to? My home airport has a massive 150 x 6000 ft runway. I have to be very aware of that when landing at other airports as I have touched down earlier than expected on runways that are not as long or wide. Thankfully nothing seriously egregious that caused significant concern but I have thought to myself that I was still a foot or two of the runway as the wheels touched.
 
Good landings are slow landings. Get comfortable down at the low end of the airspeed indicator and stop obsessing about stalls....it is angle of attack, not airspeed, that is the key factor in stalls. Keep in mind that when you maintain the recommended 1.3 Vso (calibrated, not indicated) you have a thirty-percent airspeed cushion to play with. Slow to 1.2 Vso over the fence/threshold and you must still bleed off twenty percent before the wing stops developing lift. I didn't watch the video because I knew that the villain was excess airspeed without looking at it.

It frustrates the hell out of me that instructors do such a poor job of introducing stall recognition and recovery that their students become afraid of stalls. Go to www.bruceair.wordpress.com and watch Bruce Williams demonstrate how it is done.

Bob
 
bobmrg said:
It frustrates the hell out of me that instructors do such a poor job of introducing stall recognition and recovery that their students become afraid of stalls.
Click to expand...

I think the instructors themselves don't understand the fixed relationship between airspeed, load and angle of attack. Judging by some of the comments here it's a common lack of instruction. You simply cannot land flat if the speed is where it should be, and you simply cannot touch down nose-high if the speed is too high.

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Peter Ha said:
Guess I'm just afraid of stalling base-to-final. :rolleyes:
Click to expand...
Time to go up with a better instructor and do some glides and base-to-final turns at altitude and see just how slow you have to get to stall it. A 30° banked turn increases the stall speed by only 7%, so your 150, stalling at 45 kts (52 MPH) with 10° flaps, will stall at 48 kts (55 MPH) with 10° flaps in the 30° bank. I bet you're way above that. Even on touchdown.
 
Dan Thomas said:
I think the instructors themselves don't understand the fixed relationship between airspeed, load and angle of attack. Judging by some of the comments here it's a common lack of instruction. You simply cannot land flat if the speed is where it should be, and you simply cannot touch down nose-high if the speed is too high.

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Click to expand...
I get your point, but technically you can land flat with the right speed if you shove the nose forward at the last minute.
 
Dan Thomas said:
I think the instructors themselves don't understand the fixed relationship between airspeed, load and angle of attack. Judging by some of the comments here it's a common lack of instruction. You simply cannot land flat if the speed is where it should be, and you simply cannot touch down nose-high if the speed is too high.
Click to expand...

Generally yes, but you're assuming a horizontal relative wind.
 
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