Check Gear!

[steingar]

Such luxury. My flap speed is 105 mph.  Gotta slow way down to deploy those.

[carusoam]

3 hours ago, skykrawler said:

Aarusoam.   Your admonishment aside..... it says right in the M20J POH the white arc is the full flap operating speed.

Obviously, there are differences for the models and I thought the subject was a J/K.  The M20-217 bulletin was for older models and those with cracks probably wouldn't have them if the bulletin had been performed as recommended by the manufacturer.   I've seen cracks on Bonanza flaps.  Old airplanes get cracks even if they are flown within limitations.  I try to operate my airplane to alleviate unnecessary loads.

I said milk the flaps in not extend full flaps.  5 degrees flaps will help getting to gear speed if your 8 knots high...and you should already have the prop knob pushed in.  If you are 25 knots high then you screwed up.   On a IMC instrument approach I don't extend flaps until I break out.

Glad we are on the same page...

https://www.dictionary.com/browse/admonishment

Speaking of other planes... and white arcs... when multiple levels of flaps are used, they have stepped white arcs to denote various speeds... stall variations at one end, flap variations at the other...?

You caught me... i’m Still learning how to read and write. Memorizing all the white arcs of all the various Mooneys is an interesting challenge.

Does your J have any steps in its white arc? They should be in the limitations section of the POH if they exist...

Keep in mind, Paul, the OP, was starting a discussion about all M20 pilots... his example of current events happen to be two M20Ks... but the discussion belongs with all, except three M20Ds, that have been kept in original fixed gear configuration...

How many GU landings have MSers had since Paul’s post started this conversation?   

The power of an MS conversation... we learn and re-learn amazing Mooney details in every one.

PP thoughts only, not a CFI...

Best regards,

-a-

[MBDiagMan]

As a related trivia question.  Does anyone know who was instrumental in the acceptance of the colored arcs found on today’s air speed indicators?

[HRM]

2 hours ago, MBDiagMan said:

As a related trivia question.  Does anyone know who was instrumental in the acceptance of the colored arcs found on today’s air speed indicators?

Is this a quiz or a question? Good pun too 

[Marauder]

2 hours ago, MBDiagMan said:

As a related trivia question.  Does anyone know who was instrumental in the acceptance of the colored arcs found on today’s air speed indicators?

I know at some point after WWII the FAA mandated it be used. Not sure if there was a rocket engineer behind the color schemes or some creative FAA dude saying "white looks good for flaps".

[MBDiagMan]

It was Al Mooney!  It was talked about in the biography.  He was active in getting the idea accepted in the mainstream.

[bonal]

5 minutes ago, MBDiagMan said:

It was Al Mooney!  It was talked about in the biography.  He was active in getting the idea accepted in the mainstream.

He was quite the innovator 

[skydvrboy]

14 hours ago, Skates97 said:

They must have changed it sometime in the late 60's.

For the F model, the flap extension speed changed in '68.  I know because my '67 F model came with a '68 owners manual and a previous owner had put a label on the on the ASI indicating flaps at 125 mph.  When I downloaded and printed the '67 manual I discovered the flap speed was 105.  

I fixed the labeling and asked my AI to inspect carefully for damage at annual.  Fortunately, no visible damage was found, but one has to wonder if the metal was fatigued. 

Or perhaps there was no change to the structure and further testing showed that 125 was safe.  At any rate, I now baby my flaps just to be on the safe side and only put them in around 90 - 95 mph.

[midlifeflyer]

Does anyone have a reliable answer to whether the change in the M20C flap speed from  100  to 125 mph was just a paperwork one? The TCDS definitely shows three sets of airspeed limitations for the model, based on serial number. The flap speed increase begins with serial number 68001.

I've never delved into the type certification process, so I don't know whether filing an amendment to a type certificate would be a substantially bigger deal than leaving it alone and filing a new one for the newer model.

Edited January 16, 2019 by midlifeflyer

[jaylw314]

1 hour ago, MBDiagMan said:

It was Al Mooney!  It was talked about in the biography.  He was active in getting the idea accepted in the mainstream.

That's a cool tidbit of info!

[Hank]

2 hours ago, midlifeflyer said:

Does anyone have a reliable answer to whether the change in the M20C flap speed from  100  to 125 mph was just a paperwork one? The TCDS definitely shows three sets of airspeed limitations for the model, based on serial number. The flap speed increase begins with serial number 68001.

I've never delved into the type certification process, so I don't know whether filing an amendment to a type certificate would be a substantially bigger deal than leaving it along and filing a new one for the newer model.

I thought the flap mounting changed, something to do with the sub-spar. But I won't swear to anything . . .

[Marauder]

I thought the flap mounting changed, something to do with the sub-spar. But I won't swear to anything . . .

I seem to remember something about a reinforced component being used to allow for the higher speed.


Sent from my iPad using Tapatalk Pro

[midlifeflyer]

52 minutes ago, Hank said:

I thought the flap mounting changed, something to do with the sub-spar. But I won't swear to anything . . .

Makes sense.

[bradp]

Here are two generic POHs pulled from the web.  Note that they are supposed to be for a 77J and a 78J, respectively.  Also note that my J POH for a 1977 model is up to E or F for the revisioning and these aren’t.  However note the discrepancy between the flap operating ranges.  Something changed...

 

[Oldguy]

22 minutes ago, bradp said:

Here are two generic POHs pulled from the web.  Note that they are supposed to be for a 77J and a 78J, respectively.  Also note that my J POH for a 1977 model is up to E or F for the revisioning and these aren’t.  However note the discrepancy between the flap operating ranges.  Something changed...

 

Several changes appear to have been made between these two POHs. The first uses statute miles while the second uses knots. And in the airspeed markings section the first uses CAS figures and the second uses IAS speeds. All-in-all, the figures are relatively close to each other once those differences are reconciled.

[bradp]

Agree the white arcs for full flaps are similar once CAS to IAS and knots to MPH are accounted for.  Still they are not the same  numbers despite the same airframe.  

Also note that there is no reference to use of partial flaps outside of the white arc.... it defines full flap operating range but gives no reference to use of partial flaps above the white arc.  Only tells you full flaps are ok within the white arc. 

I’m conservative with my sub spar so interpret this to mean that the white arc represents the flap operating range.  They are first lift and then drag devices.  Not speed brakes.  I use power, gear and slip in that order as my “speed brakes “

[PT20J]

Mooney has used a lot of confusing language for flap speeds in the POH over the years. The TCDS is a better source of regulatory information. It doesn't appear to me that Mooney began specifying airspeed limitations w.r.t. flap deflection in the TCDS until the J model where (for most serial numbers) the limitation is for full flaps only.

That said, I've always thought the flap system one of the weaker parts of the Mooney design. Just note how much flex there is in the mechanism in any position except up against the stops. To reduce wear and tear, I'm in the camp that uses the gear to slow down to the top of the white arc, and then I go to 15-deg for the approach. For this reason, I put the gear down and get the flaps set before the FAF or GS intercept and reduce power to go down. But, I do a GUMP check at this point. 

Skip

[midlifeflyer]

54 minutes ago, PT20J said:

Mooney has used a lot of confusing language for flap speeds in the POH over the years. The TCDS is a better source of regulatory information. It doesn't appear to me that Mooney began specifying airspeed limitations w.r.t. flap deflection in the TCDS until the J model where (for most serial numbers) the limitation is for full flaps only.

That said, I've always thought the flap system one of the weaker parts of the Mooney design. Just note how much flex there is in the mechanism in any position except up against the stops. To reduce wear and tear, I'm in the camp that uses the gear to slow down to the top of the white arc, and then I go to 15-deg for the approach. For this reason, I put the gear down and get the flaps set before the FAF or GS intercept and reduce power to go down. But, I do a GUMP check at this point. 

Skip

I fly multiple types and typically do approaches with no flaps. Some Mooneys  are among the very few retract singles  where I don't particularly like that, so I was interested in experimenting a bit. A friend suggested doing the approach the way I was, so I don't change my gear SOP, but adding approach flaps after becoming stabilized on the descent without them.  I was doubtful but since my friend was a long-time Mooney owner and CFI, I decided to give it a try - with him in the right seat  

The result in a J surprised me. Mooney flaps aren't terribly effective (compared to others) and the result was an increase in drag with about a 10-knot decrease in speed without appreciably changing glidepath.  

[PT20J]

41 minutes ago, midlifeflyer said:

The result in a J surprised me. Mooney flaps aren't terribly effective (compared to others) and the result was an increase in drag with about a 10-knot decrease in speed without appreciably changing glidepath.  

Yep, that's about what I would expect. The Mooney's flaps are different than most GA planes -- not much chord but long span. They are more effective at altering C_Lmax than adding drag and that's why the Mooney's have slightly greater reduction in stall speed than other brands. Here are some numbers for decrease in stall speed flaps down vs. flaps up in CAS from various POHs:

Mooney M20J 7 kts

Bonanza A36 6 kts

C-182T 6 kts

C-172S  5 kts

PA28-181  4 kts

Of course, there's a tradeoff -- the longer span flaps left less room for the ailerons which forced the use of a wide chord, short span aileron that has greater hinge moment -- thus the need for the beveled trailing edge to reduce the stick force. 

I'm in favor of any SOP that makes sense and can be used consistently, and I see no problem with doing it the way you suggest. Personally, I just don't like changing configuration after I start downhill, but that's just me.

[bradp]

That vid I posted of me going down on the ILS illustrates marks method pretty well.  When I’ve flow brand C or brand P I’ve found a big pitch change when I’ve added flaps (ie the Johnson bar balloon in an arrow/archer).  In the Mooney you can drive down the ILS and not change your pitch input much at all - at least half flaps - or just need a touch of up trim - thus not much imperative to have flaps configured prior to intercept.  

One of the best parts of our long short flap design is that the slight pitch moment with extension is slight nose down.  

[jaylw314]

25 minutes ago, PT20J said:

Of course, there's a tradeoff -- the longer span flaps left less room for the ailerons which forced the use of a wide chord, short span aileron that has greater hinge moment -- thus the need for the beveled trailing edge to reduce the stick force. 

Somebody mentioned this before--how does the beveled trailing edge reduce aileron forces?

[PT20J]

5 hours ago, jaylw314 said:

Somebody mentioned this before--how does the beveled trailing edge reduce aileron forces?

It's a neat aerodynamic trick. Just as an object with mass tends to move in a straight line unless acted upon by a force, air tends to flow in a straight line unless acted upon by a pressure gradient. Also, in the absence of an adverse pressure gradient, flowing air tends to follow the contour of an adjacent surface. Consider an aileron with a beveled trailing edge deflected downward. The deflected aileron increases the camber of the wing causing the desired rolling moment and the beveled edge further increases the camber locally at the trailing edge. As the air flows over the bevel it tends to follow the contour. This deflection of the air sets up a pressure gradient which results in lower pressure at the top, trailing edge of the aileron. This exerts a "pull" upward on the aileron reducing the force required to deflect it.

The Mooney aileron control system is interesting because it is definitely different than other designs of the period. It is notable for using push-pull tubes instead of the more common cables and pulleys. Is that really better? Some postulate that the push-pull tubes are better because they aren't subject to cable stretch, which is certainly true. However, there are a lot of rod ends in the Mooney and over time they can wear enough to increase the dead zone in the control system. Keep them lubed with Tri-flow. Also, the Mooney aileron controls have a lot of friction which increases break out force. Cables running over ball-bearing pulleys generally have less friction than push-pull tubes running through greased phenolic guides. At cruise speeds the ailerons tend to be pulled up (lower pressure on the top of the wing). This is the reason for rigging them down up to -2 deg. The outboard end of the aileron push-pull tube is connected to a bell crank. So, while the predominate motion of the push-pull tube is back and forth, there is a small component of fore-aft motion caused by the eccentric effect of the bell crank. This increases the friction on the outermost guide block. As the ailerons move upward, the push-pull tubes can flex under compression and put more pressure on the guides. The effect increases with airspeed. Back in the 1990's, Mooney was considering entering the JPATS competition for the next military trainer (Beech won with the T-6A). Roger Hoh was contracted to help work out handling issues and told me that at high speeds (I don't recall what the engine was -- likely a PT-6) the ailerons drifted up enough to bind the push-pull tubes such that you could move the stick (the test plane had been retrofited with a stick) left or right and it would stay where you put it!

All that being said, I like the Mooney controls enough that I recently bought another one. I just keep everything well lubed.

Skip

Edited January 17, 2019 by PT20J

[jaylw314]

2 minutes ago, PT20J said:

It's a neat aerodynamic trick. Just as an object with mass tends to move in a straight line unless acted upon by a force, air tends to flow in a straight line unless acted upon by a pressure gradient. Also, in the absence of an adverse pressure gradient, flowing air tends to follow the contour of an adjacent surface. Consider an aileron with a beveled trailing edge deflected downward. The deflected aileron increases the camber of the wing causing the desired rolling moment and the beveled edge further increases the camber locally at the trailing edge. As the air flows over the bevel it tends to follow the contour. This deflection of the air sets up a pressure gradient which results in lower pressure at the top, trailing edge of the aileron. This exerts a "pull" upward on the aileron reducing the force required to deflect it.

Wait, if:

• when the aileron is deflected down
• the upper bevel increases the camber locally so
• the pressure is lower above the trailing edge of the aileron resulting in
• increased upward force on the aileron,

Doesn't that mean the force required to deflect the aileron is INCREASED?

[Hank]

51 minutes ago, jaylw314 said:

Wait, if:

• when the aileron is deflected down
• the upper bevel increases the camber locally so
• the pressure is lower above the trailing edge of the aileron resulting in
• increased upward force on the aileron,

Doesn't that mean the force required to deflect the aileron is INCREASED?

It reduces the force required to lift the aileron back to the neutral position. It also increases lift in the wing, increasing the bank angle for a given deflecton amount (slightly).

[carusoam]

Will it balance out what is happening on the other side?

Nice details, Skip.  We just need a few more... 

Best regards,

-a-