Porpoising on landing after prop change

[Ulysse]

I replaced my prop with a new MT 3 blade propeller which is 15lbs lighter than the previous one.

I am now experiencing bumping in almost all my landings and I just cannot seem to find the right parameters. I have never bounced on landing in years of flying and something which was just natural to me has now become a "cerebral" task leading to even more bumps ☹️

I appreciate your advice/comments on this

 

 

[Danb]

Unfortunately with the center of gravity change, your going to have to make sure your on correct speed, maybe the sight picture has changed, since your prior landings were good concentration on speed then you’ll be ok again

[A64Pilot]

Your in a relearning phase, you’ll get it figured out, but until you do I’d suggest you start doing the full stall or close to it landing, landing on the mains and holding the nose off. If your proposing, your fast. i don’t look at AS indicator myself, I land on attitude. Hold the nose up, she will land, it may be a couple of hundred feet further down than you were expecting, but she won’t land until she can no longer fly.

[Oscar Avalle]

I had the same issue when I installed my MT prop. It took me a while to get used to the new landing attitude. But be patient and enjoy your new prop. I had mine installed two years ago and I love it

Oscar


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[DCarlton]

Interesting... 

[LANCECASPER]

On 7/3/2022 at 9:36 AM, Ulysse said:

I replaced my prop with a new MT 3 blade propeller which is 15lbs lighter than the previous one.

I am now experiencing bumping in almost all my landings and I just cannot seem to find the right parameters. I have never bounced on landing in years of flying and something which was just natural to me has now become a "cerebral" task leading to even more bumps ☹️

I appreciate your advice/comments on this

 

 

One of the best quotes I've ever heard on landing:

Remember, we make good landings when we want to fly and the airplane wants to land, and we make bad landings when we want to land and the airplane wants to fly! 

Wayne Fischer

Good article:

https://img1.wsimg.com/blobby/go/fd03665a-9127-4f79-a429-ee3607a81548/downloads/Wayne Fisher on Landing.pdf?ver=1619678278351

 

EDIT: Also when people transition from one length of Mooney to another (mid body to long body, etc.) they tend to porpoise the airplane on landing. There is a different feel for sure in the length but this post makes me also think the the difference in CG and the feel of the third blade (brake effect) in most long bodies also contributes to that change in feel when people transition Mooneys.

The most consistent landings I ever had in a Mooney were in a '97 Encore with the 2 blade prop (like @Ulysse's) that I had for about a year. As soon as I bought it I called Bob Cabe for some refresher training, but he  couldn't work me in for about a month. I went out a few times a week and practiced landings. When I had the numbers nailed it just wanted to land every time. By the time we flew together it was one of the few times that I seemed to make just about perfect landings with someone else in the airplane . Usually there's no one around to see those. 

[hubcap]

May want to confirm your RPM at idle since the prop change. Too fast an idle speed can cause your airspeed to be too high.

Edited July 3, 2022 by hubcap

[Schllc]

@LANCECASPER said it perfectly…

Your “rote” isn’t appropriate anymore. Assume  you are flying a new plane.

it will come with practice. 

[Austintatious]

Interesting thread... can you guys describe the difference the MT prop makes WRT landing?   I have heard it acts as more of a brake than the stock prop... Could this be causing the big difference in landing feel/technique?  Or is it a more rearward CG that causes the issue?

 

[201Mooniac]

I'm not sure, I didn't notice any significant change when I installed mine.  If I get the speed correct and the flare pitch it seems to land just the same to me.

[N201MKTurbo]

I noticed the first time I flew a Rocket that it had a lot more pitch inertia. Meaning that when you flared the plane, it wanted to keep flaring up. On any rapid pitch change, you had to consciously stop the pitch change rate. This was a subtle effect, that some may not have noticed. 
 

On the flip side, you lost inertia. When you flare, the extra weight of the old prop would tend to keep the nose going up when you flared. This effect will be reduced with your new prop. The secret is to actively fly the airplane attitude through the whole landing. You may find that you are relaxing after the main gear touches down. If you maintain your desired pitch attitude until the nose wheel is solidly on the ground, it shouldn’t bounce.

Edited July 5, 2022 by N201MKTurbo

[A64Pilot]

On 7/5/2022 at 10:53 AM, Austintatious said:

Interesting thread... can you guys describe the difference the MT prop makes WRT landing?   I have heard it acts as more of a brake than the stock prop... Could this be causing the big difference in landing feel/technique?  Or is it a more rearward CG that causes the issue?

 

If it increases drag, it’s likely due to being flatter min pitch, it’s easily adjustable on a turbine and if you flatten it, it really slows you down right now, way more than flaps.

So min pitch setting can make a big difference.

[midlifeflyer]

I'm sorry but I'm having a little trouble understanding this thread. I understand that modifications can change performance but can't figure how a change in prop can lead one to touch down nosewheel first. I can't think of a maneuver which is more about visual picture than landing. 

[M20F]

6 minutes ago, midlifeflyer said:

I'm sorry but I'm having a little trouble understanding this thread. I understand that modifications can change performance but can't figure how a change in prop can lead one to touch down nosewheel first. I can't think of a maneuver which is more about visual picture than landing. 

Ulysse stated in the original post just that he is bouncing a bit now.  Not sure where touching down on the nose wheel first comes from?

[midlifeflyer]

15 minutes ago, M20F said:

Ulysse stated in the original post just that he is bouncing a bit now.  Not sure where touching down on the nose wheel first comes from?

The title of the thread.

[M20F]

13 minutes ago, midlifeflyer said:

The title of the thread.

“Porpoising on landing after prop change.”?

Sounds as others have said his speed profile is off which I think you would agree in a Mooney hitting the mains to hard leads to bouncing/proposing.  I am not seeing where anyone is taking about landing on the nosewheel though??

[Oscar Avalle]

It is just the effect of a change in W&B on how the plane behave and how you have to learn how to fly it again.


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[midlifeflyer]

13 minutes ago, M20F said:

“Porpoising on landing after prop change.”?

Sounds as others have said his speed profile is off which I think you would agree in a Mooney hitting the mains to hard leads to bouncing/proposing.  I am not seeing where anyone is taking about landing on the nosewheel though??

That's been the definition since I was a student. Very different than a bounce due to excessive airspeed  (taking off after touching down) or excessive descent rate (potentially more problematic).  If the standard definition is not what was meant by the use if the term, sorry I misunderstood.

 

[MikeOH]

29 minutes ago, midlifeflyer said:

That's been the definition since I was a student. Very different than a bounce due to excessive airspeed  (taking off after touching down) or excessive descent rate (potentially more problematic).  If the standard definition is not what was meant by the use if the term, sorry I misunderstood.

 

A couple of comments:

1) Any misunderstanding due to the title is rapidly cleared up by READING the OP's post; he's clearly having trouble with bouncing landings.

2) No where in your cite does it state the nose WHEEL hits first; even the phrase you highlighted.  The cogent phrase is the FIRST phrase in the first sentence, "In a bounced landing that is improperly recovered" I believe the magic number is three bounces...then the nose wheel hits first!

[LANCECASPER]

The first touchdown is not a porpoise, it's a bounce. But in an attempt to recover there's usually an overreaction, then it goes into a porpoising cycle. (It's no big deal unless the mindset becomes "I'm gonna get this down no matter what")

On Mooneys each cycle gets a little worse and usually on the 2nd porpoising cycle (coming down after the 3rd bounce) there's a prop strike. Best after the first cycle just to add full power and go around. This can happen on any airplane, but is very common when people transition from a shorter body Mooney to a longer body Mooney.  There have been a lot of insurance claims on this.

[M20F]

14 minutes ago, LANCECASPER said:

This can happen on any airplane, but is very common when people transition from a shorter body Mooney to a longer body Mooney.  There have been a lot of insurance claims on this.

This is a lot more prevalent in a Ranger which has always been the more free spirited Mooney.  Executives are much more relaxed, they know the world is their oyster and they rush for nothing other than a good stock tip.  
 
Certainly the least impacted is the Statesman which debates with itself so much it never bothers to leave the tie down. 

[Shadrach]

4 hours ago, LANCECASPER said:

The first touchdown is not a porpoise, it's a bounce. But in an attempt to recover there's usually an overreaction, then it goes into a porpoising cycle. (It's no big deal unless the mindset becomes "I'm gonna get this down no matter what")

On Mooneys each cycle gets a little worse and usually on the 2nd porpoising cycle (coming down after the 3rd bounce) there's a prop strike. Best after the first cycle just to add full power and go around. This can happen on any airplane, but is very common when people transition from a shorter body Mooney to a longer body Mooney.  There have been a lot of insurance claims on this.

Planes really don't "bounce" unless they are still flying.  That being said, there is no reason to go around because of one bounce unless the runway is short or the pilot is inexperienced.  The aircraft can easily be properly flared after a bounce and landed.

Agree that "new to Mooney" pilots should probably just go around.  I think many instructors fall down when it comes to focusing on airspeed discipline. 

[Shadrach]

4 hours ago, M20F said:

This is a lot more prevalent in a Ranger which has always been the more free spirited Mooney.  Executives are much more relaxed, they know the world is their oyster and they rush for nothing other than a good stock tip.  
 
Certainly the least impacted is the Statesman which debates with itself so much it never bothers to leave the tie down. 

You could've written ad copy for RJ Reynolds in the 70s...

[A64Pilot]

This is where familiarity with a tailwheel may help, it’s real common to bounce a tailwheel airplane when wheel landing, especially a Cessna with their spring steel gear.

You learn if you bounce one you have two good options, either power up and go-around or convert the wheel into a three point landing by maintaining altitude from the bounce but slowly increasing back pressure, pretty soon she will just land nose high and it’s a three point landing. If you try to keep it a wheel landing by pushing the nose down it can get ugly, and you could even end up on your back.

You can of course do exactly the same thing with a nose wheel if it bounces, go around or keep the altitude from the bounce and just keep pulling the yoke back and she will land on the mains. Being a CB that’s how I land anyway, keep the nose off as long as possible and that helps slow her down as opposed to using brakes. Aerodynamic braking is free brakes aren’t.

We all bounce a landing once in a while, or at least I do and I don’t know where it comes from either, maybe a wind gust or more likely not paying attention as much as I should. 

Tough little airplane

Not so tough big airplane

 

[LANCECASPER]

On 7/7/2022 at 1:03 PM, Shadrach said:

.  That being said, there is no reason to go around because of one bounce unless the runway is short or the pilot is inexperienced. 

I didn't say that.

Everyone bounces one in now and then. I said "Best after the first cycle just to add full power and go around" referring to the porpoising cycle mentioned which starts after the first bounce. So if it bounces and the pilot overreacts and it goes into the porpoising cycle, IMO it's probably good to go around before you head into the 2nd or 3rd cycle.