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M20J Takeoff Flap Settings--Model Year Difference?


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#1 Parker_Woodruff

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Posted 28 July 2009 - 04:18 PM

The POH in my 1990 M20J-AT calls for 15 degrees of flaps on takeoff.  I've also noticed that climb performance is greatly increased upon raising the flaps.


SureCheck doesn't make a checklist for the M20J-AT, but they do have one for the M20J MSE.  That checklist allows for a range in takeoff flap settings from 0 degrees to 15 degrees.  However, does the POH in newer M20Js agree with SureCheck on this?


I really do like the performance and acceleration differences in operating with 0 degrees of flaps versus 15.  Obviously there are stall speed differences, etc.


 


Let me know if yall have any info on this, as well as your experiences with climb rates, etc. with and without flaps.


For what it's worth, I'm getting 500-600'/min while accelerating slowly to Vy, whereupon raising the flaps I get 900'/minute.  And this is in Texas late afternoon heat with full fuel and a passenger.  There is always the delay in the VSI that I need to make sure I'm taking into proper account.



#2 N207LS

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Posted 28 July 2009 - 10:33 PM

I can't speak to the J, but I have spent several hours with my G in countless configurations for takeoff, climb and landings.  I had a Mooney transition instructor that has 2000+ hours in Mooney transition training and had never flown a G with the Powerflow and all of the J mods, so we spent lots of time in this area trying to optomize performance.  I too fly in hot weather (FL).  We found it best at 15 degrees (per Owners Manual) on takeoff and shedding the flaps at 100'-150' AGL (clear of obstacles) for best climb at heavy weights (note that I have hydraulic flaps and they take a few seconds longer to retract).  My plane uses much less runway with 15 degrees of flaps than none at all (on paved surface about 300-400' less to get airborne).  Also, we found a slight benefit in initial climb performance that lost it's benefit at about 100 feet AGL +/-.  On grass the benefit appeared to be further enhanced by the flaps.


I routinely fly in and out of 2000' grass strips with this takeoff configuration with 800 lbs on board (of my 910 useful load) (with plenty of comfort and ability to stop if needed).  I am sure that the plane would be fine with even shorter fields, but the pilot may not be.


I hope that this helps...


Aaron



#3 bluehighwayflyer

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Posted 29 July 2009 - 09:43 AM

My '78 handbook calls for 15 degrees takeoff flaps as well. I've tried no flaps takeoffs, but ultimately decided that I generally prefer the way the airplane feels at rotation with takeoff flaps set. I typically retract them at 100 or maybe 200 feet AGL, whenever well clear of all obstacles. I've never attempted to compare climb performance between the two takeoff configurations, but your observations are very interesting to me.

#4 MooneyPilot231

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Posted 29 July 2009 - 11:37 AM

Went through this also. My plane suctioned to the runway with 10 deg. of flaps and you kind of had to jerk the yoke back to get it to lift off. I ended up moving the trim indicator about 1/8" above the "takeoff" range and using no flaps. With this setting the plane will lift off the runway on its own at about 75kts. Just a little pressure at 70kts and your off with an almost perfect climb angle. Start with the trim set at the top of the "takeoff" range and experiment from there. You might be surprised how much you like it just a little above that setting....



#5 bluehighwayflyer

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Posted 29 July 2009 - 03:27 PM

Every plane is probably different as far as the trim and flap indicators go, but I read that full down aileron deflection is equal to 15 degrees flaps. So I usually set takeoff flaps by turning one aileron down with full deflection and then visually matching the flaps to that. On my plane that technique places the flap indicator at the top of the takeoff range. I then match the trim indicator to the flap indicator and it works out pretty well.

#6 The-sky-captain

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Posted 29 July 2009 - 04:46 PM


Quote: JimR

Every plane is probably different as far as the trim and flap indicators go, but I read that full down aileron deflection is equal to 15 degrees flaps. So I usually set takeoff flaps by turning one aileron down with full deflection and then visually matching the flaps to that. On my plane that technique places the flap indicator at the top of the takeoff range. I then match the trim indicator to the flap indicator and it works out pretty well.


 Ditto here.



#7 Parker_Woodruff

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Posted 29 July 2009 - 05:45 PM


Quote: JimR

Every plane is probably different as far as the trim and flap indicators go, but I read that full down aileron deflection is equal to 15 degrees flaps. So I usually set takeoff flaps by turning one aileron down with full deflection and then visually matching the flaps to that. On my plane that technique places the flap indicator at the top of the takeoff range. I then match the trim indicator to the flap indicator and it works out pretty well.


I'll try that next time I'm out.






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