Takeoff trim

[Bob_Belville]

Just now, Mooneymite said:

On the early Mooneys the trim indicator is just a piece of plastic that can slide along the piano wire.  It easily gets out of position.

Here's a clue:

Look at where the trim indicator is after you land.  On a properly rigged Mooney, the "perfect landing trim" setting will be close to what you need for takeoff.  Landing may be about "a white indicator" width more back trim than takeoff, but it will be in the ballpark.  If your takeoff and landing trim settings are significantly different, take Clarence's advice and find a shop with rigging boards.

Not in my (short body) experience. When i land (full flaps) the nose is trimmed full up. That's not where I'd want to trim for take off with flaps @ 15 deg.  

The indicator on my '66E is an arm that pivots around a screw in the face of the wheel cover. It is moved by a lawn mower throttle type cable. One end is accessible from the belly where it's clamped to the flap actuator, the other end is a simple z bend that inserts through a hole in the indicator. With a JBar gear you might have to put the plane on jacks in order to get at the connection. 

[Mooneymite]

9 minutes ago, Bob_Belville said:

Not in my (short body) experience. When i land (full flaps) the nose is trimmed full up. That's not where I'd want to trim for take off with flaps @ 15 deg.  

The indicator on my '66E is an arm that pivots around a screw in the face of the wheel cover. It is moved by a lawn mower throttle type cable. One end is accessible from the belly where it's clamped to the flap actuator, the other end is a simple z bend that inserts through a hole in the indicator. With a JBar gear you might have to put the plane on jacks in order to get at the connection. 

Interesting.

In my experience, most aircraft are trimmed for landing such that the aircraft is pretty well trimmed for the go-around and that trim setting is close to the takeoff setting.  I'm surprised that you find full back trim appropriate, but without flying your airplane, who knows?

In the jets I fly, the trim used for landing is usually very close to the takeoff setting.  However, I've been on Mooneyspace long enough to know that there are lots of other techniques.  One size does not fit all!

 

 

Edited August 17, 2016 by Mooneymite

[Marauder]

I set my trim full nose down, yank it off the ground at 95 MIAS, suck gear up, roll upside down, set power 42" and 3500 and climb out 215MIAS.  This procedure works well, but you have to make sure the tanks are full or they may unport.  

Some may say my approach to operating my airplane is "radical", but since I installed the LED lights, my performance has gone through the roof!  Point of reference, with the LED lights, I gained 35 knots in cruise!

  

Now, now Matt. We are talking about Mooneys here, not the technique you use while flying for your airline.

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[Marauder]

On my Mooney, when I look down at the trim indicator after landing, it is typically a full bar width above the TO marked section. That would make sense to me since I land with full flaps and it would require some nose up trim.

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[Bob_Belville]

22 minutes ago, Mooneymite said:

Interesting.

In my experience, most aircraft are trimmed for landing such that the aircraft is pretty well trimmed for the go-around and that trim setting is close to the takeoff setting.  I'm surprised that you find full back trim appropriate, but without flying your airplane, who knows?

In the jets I fly, the trim used for landing is usually very close to the takeoff setting.  However, I've been on Mooneyspace long enough to know that there are lots of other techniques.  One size does not fit all!

 

 

Again, my comments are based on my short body E. On landing, as flaps are added the nose pitches down so trim is rolled up to compensate and to slow to 1.2 x Vso. 

A go around when a vintage Mooney with hydraulic flaps is configured for landing involves: 1. add power - stand on right rudder, 2. push yoke down to gain speed, 3. dump flaps while holding pitch and trimming pressure off yoke, 4. raise gear. I'd estimate that takes less than 15 seconds.  

Of course if there's 2500' or more available runway our Mooneys operate fine w/o flaps in which case trimming is within a tighter range. The Mooney Caravan formation flying is done w/o flaps, TO and landing. That reduces pilot workload with 1 less thing, actually 2, to worry about. (We also leave mixture full rich and prop full RPM. Concentration is on maintaining position relative to lead plane.) 

[Pictreed]

65E

no flaps

rotate near bottom of white arc (I'll have to look at speeds...still trying to erase Cessna RG data from the noggin).

Gear up 100-200 AGL (it was hard to break that usable runway bit but I know I can get them back down quick)

My trim indicator is too difficult to see so my trim insdicator is looking out the window at the elevator. 

[Guitarmaster]

Here is my .02.

Since you are not starting from ground zero, here's what I would (and did) do.

Fly the airplane straight and level at 80 - 85 MPH.  Essentially Vx for the airplane.  Look at your trim setting.  It should be right in the TO zone ( I don't remember where I read it, but it sticks in my head that TO trim is Vx for the airplane. )

If it is not, trim for an 80 MPH glide on final and DON'T TOUCH THE TRIM ANY FURTHER.  When you land, your airplane should be set up for TO trim.

Now to adjust the indicator:

Disconnect the torque tube at the jack screw.  There are two bolts and some safety wire to remove.  Once they are removed, turn the torque tube until the indicator is dead center of the TO range.  Re-attach and safety the torque tube and check for full travel.  The trim should now be set up properly.  I thought of it as an experimental, you don't really know what setting is correct till you fly it.

Before you do this, check your CG.  Trim will vary as much as a full "needle" width between full FWD and full AFT CG.  I did mine with just me and half tanks.  I set the trim indicator slightly nose-up for that condition.  

Side note:  I am full nose up trim when landing with full flaps and me in the cockpit.  Just the nature of the beast.  During a go-around, just make it automatic; Power, pitch, flaps, trim, gear.  

 

Edited August 17, 2016 by Guitarmaster

[Mooneymite]

1 hour ago, Guitarmaster said:

Now to adjust the indicator:

Disconnect the torque tube at the jack screw.  There are two bolts and some safety wire to remove.  Once they are removed, turn the torque tube until the indicator is dead center of the TO range.  Re-attach and safety the torque tube and check for full travel.  The trim should now be set up properly.  I thought of it as an experimental, you don't really know what setting is correct till you fly it.

 

Huh?

Sounds like you are adjusting the trim to the indicator.  Once the trim is set, the indicator should be adjusted to reflect the trim, right?

[Guitarmaster]

29 minutes ago, Mooneymite said:

Huh?

Sounds like you are adjusting the trim to the indicator.  Once the trim is set, the indicator should be adjusted to reflect the trim, right?

Yes and no.  You are adjusting the indicator to fit the actual trim setting.  Think of them as two separate systems.  The jack screw in the tail and the jack screw for the indicator and stop.  They have to hold hands correctly.

The indicator is also the trim stop.  Assuming the stops are set up properly at the factory, if you adjust ONLY the indicator by way of the set screw in the aluminum block, you will changing the up and down limits as well.  By using the above method, you will keep the factory stops and it will be adjusted correctly.  This is all making the assumption it was not changed from factory settings somewhere in it's life.  If it was, that is where the travel boards will come in handy to reset the up and down limits.  

  Caveat; as a point of reference, mine was set correctly.  We pulled the trim system out to service and re-grease everything.  When it was re-installed, we didn't mark where the trim was when it was disassembled so I took a guess based on where it usually sits and started there.  

After, I tested the flight envelope.  At redline, I was able to trim hands-off.  Same with approach to landing with full flaps.  If there is a problem at end of the envelope, then it would be time to adjust the trim block.

Is it perfectly factory?  Probably not, but it is really close!



 

Edited August 17, 2016 by Guitarmaster

[Mooneymite]

5 minutes ago, Guitarmaster said:

Yes and no.  You are adjusting the indicator to fit the actual trim setting.  Think of them as two separate systems.  The jack screw in the tail and the jack screw for the indicator and stop.  They have to hold hands correctly.
 

Mmmmmm.....

[Guitarmaster]

BTW, I saw my first Mite at OSH, very cool!

[N9201A]

If you don't believe you can leave power/RPM in throughout climb, or safely takeoff/land without flaps...don't. But don't expect those of us that know better to either give a hoot, validate your procedure, or change what we do as the situation dictates. And stay "on the step" while you're at it!

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[DXB]

21 hours ago, Bob_Belville said:

Not in my (short body) experience. When i land (full flaps) the nose is trimmed full up. That's not where I'd want to trim for take off with flaps @ 15 deg.  

The indicator on my '66E is an arm that pivots around a screw in the face of the wheel cover. It is moved by a lawn mower throttle type cable. One end is accessible from the belly where it's clamped to the flap actuator, the other end is a simple z bend that inserts through a hole in the indicator. With a JBar gear you might have to put the plane on jacks in order to get at the connection. 

Interesting discussion guys. My C's trim characteristics are as follows:

-I seem to have way more up trim than I will ever need.  

-It's common for me to run out of nose down trim for higher speed descents

-I typically need slight nose down pressure on my takeoff roll as I gain speed with standard takeoff flaps

-I always have to trim nose down a bit after takeoff for stable climb

-With control pressures trimmed off at full flaps on short final, the needle indicates a modest deflection above the takeoff setting (maybe 2 needle widths)

It sounds like I need something adjusted, in the opposite direction from Bob's adjustment?

[carusoam]

Notes on trim range...

My 65C was full flaps and full up trim on landing wth two people...  Good Flight instructors can't agree to this.  It's not a proper way of setting trim.

T/O was at the top end of the T/O range.  Putting people in the back is why there is a range...

I ran out of down trim once.  The new ADF wire on the tail was preventing the tail moving back properly.  The trim moved but the tail was hanging on the wire.  Imagine the discussion after that event...

With full up trim, the ADF wire needs a long spring or it is going to sag some.

The O works about the same except the flaps and trim happen at the same time in a motorized way and there is no ADF wire...

PP discussion points, not CFI....

Best regards,

-a-

[Hank]

My standard short body takeoff is Flaps Up, Trim a needle width above Takeoff; when heavy, Flaps to Takeoff, Trim to Takeoff. In both cases, I also trim Down during climb, more down after leveling, then adjust as needed after setting power and leaning. Cruise Trim is often halfway from Takeoff to Full Down.

For landing, I set Flaps as required to hit my landing spot and trim hands off at 90 mph downwind and again at 85 mph on final. By short final when I'm decelerating to the runway, I don't mess with trim anymore, it's all throttle back and yoke for speed. The Trim is generally very close to the Takeoff mark when I look down the next time.

My Trim indicator is a wide horizontal line that moves straight up and down, just like the Flap indicator. I've not taken it apart to see how it works, but would be unsurprised to find a sheathed cable there. Trim is hand cranked, Flaps are electric and move as long as I hold the wide toggle switch over.

[Yetti]

I don't like using half flaps on take off (means I forgot to clean up the plane from landing)  because that will be the one time I don't double check everything and I will fly for several miles wondering why I am going so slow and then have to thump myself in the back of the head for being a dumb bunny

[Guest]

13 hours ago, Guitarmaster said:

Yes and no.  You are adjusting the indicator to fit the actual trim setting.  Think of them as two separate systems.  The jack screw in the tail and the jack screw for the indicator and stop.  They have to hold hands correctly.

The indicator is also the trim stop.  Assuming the stops are set up properly at the factory, if you adjust ONLY the indicator by way of the set screw in the aluminum block, you will changing the up and down limits as well.  By using the above method, you will keep the factory stops and it will be adjusted correctly.  This is all making the assumption it was not changed from factory settings somewhere in it's life.  If it was, that is where the travel boards will come in handy to reset the up and down limits.  

  Caveat; as a point of reference, mine was set correctly.  We pulled the trim system out to service and re-grease everything.  When it was re-installed, we didn't mark where the trim was when it was disassembled so I took a guess based on where it usually sits and started there.  

After, I tested the flight envelope.  At redline, I was able to trim hands-off.  Same with approach to landing with full flaps.  If there is a problem at end of the envelope, then it would be time to adjust the trim block.

Is it perfectly factory?  Probably not, but it is really close!



 

There are far to many guesses and assumptions in your procedure.  The maintenance manual for your plane has the tools and procedures to do the job correctly.

Clarence

[MyNameIsNobody]

The only time I look at the trim indicator is when I preflight.  Otherwise I trim the plane.  Flaps?  I do two and four pumps and I look out the window.  Grumpy and living in Sunny Southern California?  Whatever.

[luv737s]

On 8/16/2016 at 8:38 PM, TheTurtle said:

This thing gets off the ground in a hurry and wants to climb, then when the gear goes up it really wants to climb.  Kind of a lot to handle with a johnson bar in one hand.  Whats your process on takeoff?

takeoff roll
75mph slight pull to break off
positive rate
no more usable runway gear up
trim like hell
Flaps up
2500ish RPM
trim for 120

Im thinking I need to take another minute to trim down before raising the gear or do some tests with less than takeoff trim.

When I first started flying my 1962 C model I noticed the nose was heavy and I started using more nose up trim.  I also noted the plane was 120 pounds heavier than the factory model (1962).  Trim in those days was based on two bladed prop and the panel was naked.  I have a full panel now and a three bladed prop...guess where all the weight is???   I think over the past 52 years the trim may change from factory settings and the original trim settings may not be as accurate   My choice was to take off with the trim set and pull harder or add more nose up trim.    Just my observation on my plane. 

[Shadrach]

19 hours ago, Mooneymite said:

Here's a clue:

Look at where the trim indicator is after you land.  On a properly rigged Mooney, the "perfect landing trim" setting will be close to what you need for takeoff.  Landing may be about "a white indicator" width more back trim than takeoff, but it will be in the ballpark.  If your takeoff and landing trim settings are significantly different, take Clarence's advice and find a shop with rigging boards.

Based on what? Differences in loading and speed will require different trim settings for a desired pitch at a given AOA/airspeed.

My 67 F has perfectly set flap and trim indicators (I set them myself during after doing some interior work). For standard take offs,  I set flaps and trim in the "take off" position, take the runway, advance to full throttle and hold about 5 lbs of back pressure on the yoke.  I alternate my view between engine monitor and outside. The plane flies off at nearly the same attitude every time, the speed at which it rotates varies with weight.  On landing, trim is always well aft of take off position.  If I'm light fuel with just me and a front seat pax, I often hit the nose up trim stop during final.

IIRC, the elevator travel and neutral position is not the same for all vintage birds. This account for the difference you're experiencing. It could also bee that you fly faster approaches. If it's just me and 1/2 tanks, I'm trimmed for 65/70mph on final. 

[Shadrach]

On August 16, 2016 at 9:38 PM, TheTurtle said:

This thing gets off the ground in a hurry and wants to climb, then when the gear goes up it really wants to climb.  Kind of a lot to handle with a johnson bar in one hand.  Whats your process on takeoff?

takeoff roll
75mph slight pull to break off
positive rate
no more usable runway gear up
trim like hell
Flaps up
2500ish RPM
trim for 120

Im thinking I need to take another minute to trim down before raising the gear or do some tests with less than takeoff trim.

Get you gear up as soon as pos rate is established (leaving gear down has no logical benefit and it inhibits climb)

leave all the knobs forward (reduce to 2500 if you're really concerned about noise)

check engine parameters

flaps up at 90mph 

retrim 

check engine parameters

trim for cruise climb

 

[Mooneymite]

5 minutes ago, Shadrach said:

Based on what? Differences in loading and speed will require different trim settings for a desired pitch at a given AOA/airspeed.

Based on a short body on an average day.

If your short body is properly set up, when you set your trim and flaps as the POH suggests,, then it will be generally "in trim" as long as your CG is within limits.  If it isn't then a session with Clarence's boards might be appropriate.

It is entirely possible to become familiar and comfortable with an aircraft which is not set up according to specs.

There is a wide variance of what pilots consider "in trim" for landing, but generally the trim indicator after landing will be "somewhat" above the takeoff mark.  I disagree with those pilots who habitually land with a great deal of back trim for landing.  In case of go-around, the trim should be closer to the takeoff setting to avoid pitch up, but that's my opinion, not per POH.  Just makes sense to set trim for approach speed, not the landing flare.  YMMV

[Guitarmaster]

1 hour ago, M20Doc said:

There are far to many guesses and assumptions in your procedure.  The maintenance manual for your plane has the tools and procedures to do the job correctly.

Clarence

You are correct sir.  If I was starting from scratch, I would definitely use the travel boards to get to factory specs then adjust from there.  
As always Clarence, thanks for your expertise and actively participating here!  

Edited August 18, 2016 by Guitarmaster

[Guitarmaster]

10 hours ago, DXB said:

Interesting discussion guys. My C's trim characteristics are as follows:

 

-It's common for me to run out of nose down trim for higher speed descents

 

You should be able to fly at redline hands-off with a little trim to go.  If you can't, there is a problem.  I had some hard grease in the jackscrew that was causing an artificial block thereby causing me to hold pressure on the yoke above 175MIAS. 

[luv737s]

I have included the W&B from my mooney out of the factory (yes I have all the original documents) and the current W&B redone about 2 years ago.  Partner wondered why I carry 80 LBS of ballast when I fly SOLO.   I think every plane is unique and should be checked above the factory norm.

Mike

CG.pdf