The Mooney Pull & Take Off Trim ???

[DCarlton]

On 11/11/2022 at 8:50 PM, PT20J said:

Takeoff trim setting should result in the trim assist bungees holding the elevators in trail with the horizontal stabilizer. If you adjust the trim for that condition, where does your trim indicator point?

Although I didn't answer your question precisely (sorry), the first pic shows how I landed, and typically land, with 3 to 3.5 pumps of the flaps (approx 3/4 flaps).  The second elevator pic, shows the elevator when the trim is set to the current "TAKE OFF" position.  Setting it to the TAKE OFF position makes for a lively (IMO undesirable) pitch up off the runway requiring forward pressure on the yoke.  Using the landing position as depicted works great during take off too.  I'm going to start checking the position as part of my pre flight walk around.  Based on the discussion and pics, it looks like I'm still a little nose up at takeoff which may explain why I feel like I need to hold it on the runway a few extra seconds until the speed builds.  I think my trim indicator needs adjustment.... 

 

[PT20J]

One thing is to wiggle the elevator slightly up and down to find the true center of the springs as there is always some friction that may be holding it slightly up or down. But, I would say that your first picture looks right for takeoff with 15 deg of flaps and landing with about the same (maybe a little more). Landing with full flaps should result in a more nose up trim setting. As @M20Doc suggested, it would be good to verify the trim rigging and then adjust the indicator if necessary to avoid covering up a trim rig issue by changing the indicator.

We all get really used to our airplanes. It is great when we get a chance to compare them with others since that's often the only way to see that something is just different and warrants investigation.

Skip

[A64Pilot]

I’d let sleeping dogs lie, you know where it’s supposed to be, just go with that, my luck if I were to adjust it, I’d break some small impossible to get part.

My J the TO and landing trim is WAY above the T/O position mark so it’s likely out too, I had thought it’s because I pretty much fly way Fwd CG with two people and no baggage etc. But maybe it’s just out of rig.

For those that have the same trim for landing and takeoff, it’s my opinion your doing the safest thing, in the event of a go-around it’s no issue at all, it’s just a normal takeoff control pressure wise.

It’s not what I used to do, I used to trim full up for landing as it’s easy, no aft pull on the yoke, but one day I did a go-around and was astonished at how hard I had to push to keep from a zoom climb / stall and changed my technique, I was flying Bush / Ag and go-arounds are more common in off airport ops.

People are afraid of a go-around and they shouldn’t be, my J model at sea level and max gross weight or slightly higher does a go-around just fine at full flaps and gear down, the higher powered aircraft surely do better, but she goes around just as easily and just as well as a Cessna or Beech.

Go out and practice them, don’t sweat trying to reconfigure the aircraft until well after your airborne and safely climbing, it’s not a timed event

[Shadrach]

Interesting side bar.  Our aircraft are just 7 serial numbers apart but have a completely different tail tie down.  Mine has a tail skid with an eye bolt that is identical to the factory wing tiedowns. 

[David Lloyd]

Is the aerodynamic tail tie down a Laser part? I have one like that also.  
The original metal spring, has anyone ever landed nose up enough to hit it?

[Shadrach]

@DCarlton

looks to me like your trim is set up identical to mine. So this must be a difference in technique.

 

[DCarlton]

15 minutes ago, Shadrach said:

@DCarlton

looks to me like your trim is set up identical to mine. So this must be a difference in technique.

 

That's interesting.  The elevators do look very similar in the TAKE OFF position.  Would be nice to confirm if that slight nose up trim is correct to spec for the '67F.  Regarding technique, all I can tell you is my plane pitched up rather suddenly and quickly in that position without any back pressure whatsoever.  I have a three blade on mine; wondering if our W&B is similar.  Regardless I'm going to explore trim positions between my typical landing position and TAKE OFF a bit more.  

[Shadrach]

1 hour ago, DCarlton said:

That's interesting.  The elevators do look very similar in the TAKE OFF position.  Would be nice to confirm if that slight nose up trim is correct to spec for the '67F.  Regarding technique, all I can tell you is my plane pitched up rather suddenly and quickly in that position without any back pressure whatsoever.  I have a three blade on mine; wondering if our W&B is similar.  Regardless I'm going to explore trim positions between my typical landing position and TAKE OFF a bit more.  

Control feel is kind of subjective. what feels one way to some can feel differently to others. Your three bladed prop should make your plane more nose heavy than mine not less so.
Much of this could be speed and configuration related. If I recall correctly from previous discussions, you like to do partial flap landings and carry quite a bit more speed to the fence than I do (I think you said 85 mph is typical).

I’m usually full flaps and trimmed for ~70mph by short final unless heavy. Even at max gross weight 1.3 VSO is only about 80mph and I try to be at 1.2 when I cross the threshold. Those different configurations and final approach speeds generate necessitate different trim positions.

Same with takeoff. Manual gear Will train you to get the airplane airborne quickly in the gear up at the slowest speed possible. I want the airplane off the ground as quickly and cleanly as possible so I can start cleaning up the air frame. I sometimes get a bleat from the stall horn as the mains come off the runway.  I want the gear up as soon as I have positive rate and that means reaching for the gear handle at about 75-80mph. 

[DCarlton]

38 minutes ago, Shadrach said:

Control feel is kind of subjective. what feels one way to some can feel differently to others. Your three bladed prop should make your plane more nose heavy than mine not less so.
Much of this could be speed and configuration related. If I recall correctly from previous discussions, you like to do partial flap landings and carry quite a bit more speed to the fence than I do (I think you said 85 mph is typical).

I’m usually full flaps and trimmed for ~70mph by short final unless heavy. Even at max gross weight 1.3 VSO is only about 80mph and I try to be at 1.2 when I cross the threshold. Those different configurations and final approach speeds generate necessitate different trim positions.

Same with takeoff. Manual gear Will train you to get the airplane airborne quickly in the gear up at the slowest speed possible. I want the airplane off the ground as quickly and cleanly as possible so I can start cleaning up the air frame. I sometimes get a bleat from the stall horn as the mains come off the runway.  I want the gear up as soon as I have positive rate and that means reaching for the gear handle at about 75-80mph. 

I think I was 80 over the fence the last time I flew.  Working on getting the speeds down based on previous discussions.  As far as takeoff, understand the 3 blade would make the nose heavier but I didn't want to make any assumptions about how that would impact the transition to flying state once enough lift is generated (I could imagine it being less intuitive and perhaps more abrupt).  I plan to explore the trim settings a bit more during take off.  I'm sure my habits were influenced by operating off of a 5000 foot near sea level runway for 30 years.  

[Shadrach]

10 minutes ago, DCarlton said:

I think I was 80 over the fence the last time I flew.  Working on getting the speeds down based on previous discussions.  As far as takeoff, understand the 3 blade would make the nose heavier but I didn't want to make any assumptions about how that would impact the transition to flying state once enough lift is generated (I could imagine it being less intuitive and perhaps more abrupt).  I plan to explore the trim settings a bit more during take off.  I'm sure my habits were influenced by operating off of a 5000 foot near sea level runway for 30 years.  

I will also take note as I am hoping to do a post annual ops check flight this afternoon.

[GeeBee]

All this reminds me why it is important to paint an index on your stab so you are sure your indicator is correct. I always move the trim back to T/O position after landing so on the next preflight, I can look at the index and know the trim indicator is correct.

 

[carusoam]

Nice one GB!

Thanks for sharing…

Best regards,

-a-

[carusoam]

For DC…

We have covered a ton of variables….

Your T/O and landing trim may be very close to each other…

With more experience exploring your plane’s design envelope…. The two trim settings should separate under book conditions…

If you don’t use book conditions…

1) If your T/O configuration is identical to your landing configuration….  The trim may be very close… 

2) The book often has us landing using full flaps… X-winds are often T/O flaps…

and T/O with either no flaps or T/O flaps….

 

As your landing speed gets moved back to the short landing procedure…

• The flaps are full down…
• The speed is trimmed near the top of the elevator’s range…

If you T/O with the elevator near max, it will be very similar to doing a go-around…

The nose will try to point towards the sky… as PIC you are in control of not letting the plane fly you….

 

The trim indicator, properly set up, looks very similar… from short body to long body Mooney….

 

The trim indicator…. Is probably set for a 75ias departure…

It only takes being a few mm high to have the stall horn blaring… or a few mm low to have a low ascent rate…

 

The trim does a nice job of lightening the load on our arms….  It isn’t very good as a set-and-forget speed controller…

 

Soooooo… no matter what the indicator is showing… use the ASI for controlling the speed….   

PP thoughts only, never a CFI….

Best regards,

-a-

[carusoam]

Wait there’s more…. 

Weight and balance has a way of changing things up a bit…

But, that is why we have a range on the indicator… and a needle as a pointer….

It isn’t always a single T/O position…

If our balance is at the…

• front of the envelope… use the top of the T/O trim range…. (More trim with only front seaters…)
• back of the envelope… use the bottom of the T/O trim range… (less trim with back seaters…)

Either way…

Mooney gear legs are designed to not being pointing skywards like a trainer… 

If the plane departs the ground without pulling back….

Check the indicated airspeed when this happens….

1) The speed will exceed recommended Vr…

Note: Being on the ground above Vr can lead to experiencing the eight second ride…. Depending on how worn the nose gear parts are…

2) The B, in WnB, may be pretty far back…

 

By the time we are at flying speed… with or without springs holding the elevator up…. The elevator flattens out in the airstream…

 

Before Vr…

A small amount of back pressure gets your arms ready… to feel the control….

At Vr…

The nose comes up, as directed by your pull…

Typically…

We judge when Vr will happen…

If we wait for Vr to arrive, then pull….

We will miss the actual Vr by several knots as we continue to accelerate….

Kind of an example of getting behind the plane during T/O…. 

More PP thoughts, probably not very well explained… not a CFI…

Best regards,

-a-

[Andy95W]

13 hours ago, David Lloyd said:

The original metal spring, has anyone ever landed nose up enough to hit it?

Yes.

I’m not sure if it was the previous owner who flew off his 1400’ grass strip on his Texas ranch, or me flying into my 2000’ asphalt and making the first turn off (about 1100’).  And mine’s an M20C, not a long body that sits tail low.

This is mine:

[carusoam]

9 minutes ago, Andy95W said:

Yes.

I’m not sure if it was the previous owner who flew off his 1400’ grass strip on his Texas ranch, or me flying into my 2000’ asphalt and making the first turn off (about 1100’).  And mine’s an M20C, not a long body that sits tail low.

This is mine:

My M20C’s tail tie down ring was flattened on the bottom…

Not sure if the spring could hit the ground with the ring in place….

But, the ring had an offset angle as if it had been modified/bent….  
 

The tail tie down ring is no ordinary eye-bolt….

Best regards,

-a-

[Hank]

Did Mooney stop putting advice like this when they changed from Owners Manuals to POHs?

I find this very accurate for my C. I pull to lift off at 70 (75 if heavy, maybe a little more if the wind is very gusty),then relax some of the pull to climb out at Vx initially, pushing and trimmed for lower speed as I clear nearby terrain / obstacles, etc.

[Hank]

3 minutes ago, carusoam said:

My M20C’s tail tie down ring was flattened on the bottom…

Not sure if the spring could hit the ground with the ring in place….

But, the ring had an offset angle as if it had been modified/bent….  
 

The tail tie down ring is no ordinary eye-bolt….

Best regards,

-a-

The tail tie down is not a normal eye bolt, and the spring is attached at the front and bent upwards at the back.

[carusoam]

The casual conversation style of the early owner’s manual gets left in the dust…

The POHs seem to be written in a clean room, guarded by a legal team… 

Ranges, as desired… become set points with few options….

Maximum safety of the average pilot can be expected by following the POH….

When not an average pilot…. There are some things that can be done better than the POH….   (Sounds risky though…)

Best regards,

-a-

[DCarlton]

52 minutes ago, carusoam said:

Wait there’s more…. 

Weight and balance has a way of changing things up a bit…

But, that is why we have a range on the indicator… and a needle as a pointer….

It isn’t always a single T/O position…

If our balance is at the…

• front of the envelope… use the top of the T/O trim range…. (More trim with only front seaters…)
• back of the envelope… use the bottom of the T/O trim range… (less trim with back seaters…)

Either way…

Mooney gear legs are designed to not being pointing skywards like a trainer… 

If the plane departs the ground without pulling back….

Check the indicated airspeed when this happens….

1) The speed will exceed recommended Vr…

Note: Being on the ground above Vr can lead to experiencing the eight second ride…. Depending on how worn the nose gear parts are…

2) The B, in WnB, may be pretty far back…

 

By the time we are at flying speed… with or without springs holding the elevator up…. The elevator flattens out in the airstream…

 

Before Vr…

A small amount of back pressure gets your arms ready… to feel the control….

At Vr…

The nose comes up, as directed by your pull…

Typically…

We judge when Vr will happen…

If we wait for Vr to arrive, then pull….

We will miss the actual Vr by several knots as we continue to accelerate….

Kind of an example of getting behind the plane during T/O…. 

More PP thoughts, probably not very well explained… not a CFI…

Best regards,

-a-

Nicely explained.  Enjoy your summaries.  Now I’m wondering ….  If you follow the POH crosswind procedure as posted by Hank, how much above Vr would that typically be? I suppose I would admit now to using the crosswind procedure for every takeoff.  It seems to work for high DA situations too.  I’m interested in improving technique based on the discussion but, from a practical perspective, it does seem like we’re splitting hairs based on a few mph delta between the various procedures. Isnt there sometimes an advantage to doing something the same way every time ?  If it’s good for crosswinds how bad can it be for normal takeoffs ?  

[carusoam]

1 minute ago, DCarlton said:

Nicely explained.  Enjoy your summaries.  Now I’m wondering ….  If you follow the POH crosswind procedure as posted by Hank, his much above Vr would that typically be? I suppose I would admit now to using the crosswind procedure for every takeoff.  It seems to work for high DA situations too.  

See if your POH has descriptions for T/O and landing in X-winds…

Mostly… T/O in X-wind, the ground handling part gets adjusted, the T/O is nearly the same, the post rotation got discussed around here last week… (follow the extended centerline vs. follow the heading…)

The big difference… how much flap to use for X-wind landings… often T/O flaps are desired… because cross controlled rudder/ailerons are so draggy, full flaps add even more drag… avoid accidentally slowing before getting to the ground….

Keep in mind… when t/o flaps are used for landing…. Short field performance has left the discussion….   

Often, elevated X-winds aren’t very steady… this leads to approaching at a higher speed…. 1/2 the gust speed added…

 

Soooo… there is probably a calculated change to Vr with a cross wind…. But… our airspeed indicator keeps displaying what is happening relative to the wings…. Where it counts.

The important thing to consider with all winds… what changes as the plane leaves the ground and climbs past obstacles… including tree lines and buildings….

Departing into an increasing headwind is good…..

Turning away from a headwind can be terrible… without enough airspeed to handle the difference…

PP thoughts only,

-a-

[carusoam]

All of that leads to a discussion regarding….

Slip to a landing….

-or-

Crab to a landing with a rudder kick at the end to align with the runway centerline…

New thread…

-a-

[Pinecone]

7 hours ago, Hank said:

Did Mooney stop putting advice like this when they changed from Owners Manuals to POHs?

I find this very accurate for my C. I pull to lift off at 70 (75 if heavy, maybe a little more if the wind is very gusty),then relax some of the pull to climb out at Vx initially, pushing and trimmed for lower speed as I clear nearby terrain / obstacles, etc.

That is the take off procedure that I use in my 252.

 

But a lot of discussion about "Vr".  There is no Vr for light aircraft.  Vr is a jet thing, where at a certain speed, you pull to a specified pitch attitude, in degrees, and hold it until the aircraft breaks ground.  Then you transition to a climb pitch.

We add back pressure starting around a certain speed

[EricJ]

20 hours ago, GeeBee said:

All this reminds me why it is important to paint an index on your stab so you are sure your indicator is correct. I always move the trim back to T/O position after landing so on the next preflight, I can look at the index and know the trim indicator is correct.

 

Might also use the opportunity to check the fasteners on your inspection plate.

[EricJ]

11 hours ago, Andy95W said:

Yes.

I’m not sure if it was the previous owner who flew off his 1400’ grass strip on his Texas ranch, or me flying into my 2000’ asphalt and making the first turn off (about 1100’).  And mine’s an M20C, not a long body that sits tail low.

This is mine:

In my experience it's pretty rare on Cessna 150s, 172s, etc., that the tail tie down ring is still round on the bottom.