Maximum Flap speed - What does really mean?

[flyingvee201]

I have a 1967 M20F with J mods (windshield, cowling, side windows, gap seals, step removed)

 

Does the maximum speed mean for FULL flaps? or no matter what position?

 

thanks

 

[rbridges]

You could probably fudge the value with the first notch of flaps since there is less drag, and therefore, less stress on the flaps.  I haven't seen anything written, so I don't like to chance it.  I was told you can introduce stress cracking in some of the linkage by having your flaps down at too high of a speed.

 

And to be honest, I've taken off, forgotten to release the flaps and exceeded the flap speeds a time or two.

[AmigOne]

And to be honest, I've taken off, forgotten to release the flaps and exceeded the flap speeds a time or two.

 

Haven't we all !!!  Most of the time however is forgetting to retract them a condition quickly determined by failing to reach supersonic speed.

[fantom]

You don't have a serious issue until you start forgetting to retract the gear

[Joe Zuffoletto]

You don't have a serious issue until you start forgetting to retract the gear

 

Yes, I've heard this is an issue with Cirrus pilots transitioning to Mooneys. 

[Jamie]

Now I'm curious about the difference in construction of the ailerons and the flaps. There is no "maximum aileron deflection speed". So I wonder if the flaps get overstressed, or they go into flutter, disrupt the flow over the tail, etc. What determines Vfe?

[co2bruce]

I have been told with one notch of flaps your ok with another 10 - 15 kts on my long body. I have forgotten to retract them once (hehe) and took it even faster. I would guess your safe to 120 - 125kts with 10 degrees. (this is not an endorsement to go beyond the white arc on your airspeed indicator, just an opinion)  

[rbridges]

Now I'm curious about the difference in construction of the ailerons and the flaps. There is no "maximum aileron deflection speed". So I wonder if the flaps get overstressed, or they go into flutter, disrupt the flow over the tail, etc. What determines Vfe?

 

the previous owner of my plane said it was stress, not an airflow issue FWIW.

 

this is from an email he sent me.  

Don’t push the flap speed to much. There is a spar in the back of the center wing that is visible with the belly pan off. The flap actuator is bolted to that spar. They can crack if too much stress is applied to the flaps.

[WardHolbrook]

It's discussions like this one that can have a tendency to cause some pilots to rationalize that it's OK to fudge a bit on the limitations published in the POH. Yes, there are safety margins built in to the various limitations for those occasional "ballistic overshoots" that we all experience from time to time and busting a speed by a few knots isn't going to cause catastrophic airframe failure. What those margins aren't designed to do is give you Carte Blanche to ignore the limitation. Let's face it, the Mooney has a reputation of being a bit slippery and anything to help you get it slowed down is a good thing. The factory sets those type of speed limitations a high as they possibly can, it makes the airplane easier to manage in the pattern. We can all have our various opinions on stuff like this, but the only opinion that matters is the one published in the POH.

[Hank]

While the Owner's Manual does not say for certain, I treat is as "maximum speed for flap extension at all." Safer that way, too.

 

Now I'm curious about the difference in construction of the ailerons and the flaps. There is no "maximum aileron deflection speed". So I wonder if the flaps get overstressed, or they go into flutter, disrupt the flow over the tail, etc. What determines Vfe?

 

There are two big differences betwees flaps and ailerons:

• The flaps are mounted to a short sub-spar at the rear of the wing
• Flap deflection is much greater [down to 33º; ailerons go up~15º and down 8º].

[FloridaMan]

I heard the cracks could be caused by overpumping them too, for those of us with hydraulic flaps. If the handle doesn't move, don't push it. I've forgotten whether I've put in 3 or 4 pumps on final and just leave the handle up in that case. 

[aviatoreb]

You don't have a serious issue until you start forgetting to retract the gear

 

Not as bad as the other way.

[John Pleisse]

79 J. My POH says "full flaps".

[Oscar Avalle]

Haven't we all !!!  Most of the time however is forgetting to retract them a condition quickly determined by failing to reach supersonic speed.

Happy to hear that I am not the only one...

[N201MKTurbo]

You take off, climb to altitude, level off, trim, adjust the power super precisely, then you settle in for the flight.....

You glance at your ground speed and curse the weather man for getting the winds aloft wrong...

Then you look at the airspeed and it is low, you check your power settings again and wonder what is wrong...

Then you see that gear handle......

[jetdriven]

Or the flap lever, A 1977 M20J will only go 140 knots with the flaps at takeoff

[M204ever]

Operators Handbook says "maximum flap operating speed", additionally there is a white arc that denotes the speed range in which the flaps may be "safely lowered"...no room for interpretation.

 

I've been playing a lot with aileron adjustment to get her flying straight until I learned that the roll tendancy was a tiny litte misalignment of one flap. Half a turn only of the outer flap bearing fitting makes a big difference in roll behaviour. So, the airspeed should be kept right before extending the flaps. I must admit... it is inviting to use them to slow down in the pattern..

[M016576]

It's discussions like this one that can have a tendency to cause some pilots to rationalize that it's OK to fudge a bit on the limitations published in the POH. Yes, there are safety margins built in to the various limitations for those occasional "ballistic overshoots" that we all experience from time to time and busting a speed by a few knots isn't going to cause catastrophic airframe failure. What those margins aren't designed to do is give you Carte Blanche to ignore the limitation. Let's face it, the Mooney has a reputation of being a bit slippery and anything to help you get it slowed down is a good thing. The factory sets those type of speed limitations a high as they possibly can, it makes the airplane easier to manage in the pattern. We can all have our various opinions on stuff like this, but the only opinion that matters is the one published in the POH.

I agree... If a pilot starts to make it their SOP to overspeed the gear or flaps to enter the pattern, then perhaps it's time to fly to a better pattern (or suffer the consequences)!