Short field take-offs in M20R Ovation

[RobertGary1]

As a rule of thumb I've found that in general the first 1/2 of flaps is more lift than drag. The second half is more drag than lift. Its why bringing the flaps up to about 1/2 position is the procedure I've seen on almost all planes, including jets as part of go around.

 

-Robert

[r0ckst4r]

5 hours ago, donkaye said:

Poorly written in the POH.  NO FLAP EXTENSION above 110 Knots.  That has been discussed numerous times in the past 20 years.  At one point Mooney considered raising the approach flaps airspeed to 140 knots, but testing showed, if I recall correctly, wing torsion issues possibly related to CG position.  I don't remember exactly, but I do know it was never implemented.  Bottom line to repeat: NO FLAPS ABOVE 110 KNOTS.

Yeah this particular line always confused me.  They mention over and over again that 110 KIAS is the limit for any flap extension then they toss in this full flaps below 110 KIAS.  Maybe this was revised later.  I think what they meant to say is "flaps as required below 110 KIAS" lol

[carusoam]

Mooney doesn’t seem to use a flap operating speed, separately from a flap extended speed...
 

Often pilots new to the Mooney... expect that the first notch of flaps has no speed limit associated with it...
 

Oddly enough, that unstated rule comes from some primary trainer somewhere... where the rule in the book says... and the CFI says... we’re not exactly the same... 

Best regards,

-a-

[PT20J]

Mysteriously, The 205 had an increased 15-deg flap speed of 126 KIAS. Anyone know what was different? Later models of the J deleted this.

Skip

[carusoam]

The O gets a 59 - 110 kias range for its flap operating speeds...

110 is pretty close to 126mph...

“Lower limit is maximum
weight Vso in landing con-
figuration. Upper limit is
maximum speed per-
missable with flaps extended...“   From the O’s POH....

 

Definitely don’t want to try and move the flaps at 59kias... 

Moving flaps above this range could bend the spar the flaps are attached to...

Moving flaps below this range could bend everything else....

PP observation only, not a CFI...

Best regards,

-a-

[PT20J]

126 knots = 145 mph

[carusoam]

Skip,

I just dropped the ball on that one, then accidentally kicked it really far away... 

Best regards,

-a-

[PT20J]

Anthony, I should have posted the page from the TCDS to make it clear. I think 24-3000 — 24-3078 were the 205s. They had higher gear speeds, too. Not sure why.

There is sometimes confusion about flap speeds on other models due to the wording in the TCDS and POH about the limitation applying to full flaps. But, since there is no published higher speed for partial flaps, the full flap speed must be taken as applying to lesser flap extensions as well.

Skip

[Roger Wilco]

On 9/28/2020 at 1:29 AM, r0ckst4r said:

I have noticed that in our POH they give a general take-off configuration of 10 degrees flaps for all take-offs, being regular or short or soft.  I am comfortable with this on my usual luxurious paved runways of around 3000 ft and with my massive home base runway of 5000 ft.  My question is more of a point of curiosity.  Why do they not use a full flaps setting for a short or soft field take-off?  When performing a go-around the flaps are already full down at 33 degrees when full power is applied then retracted later.  Am I missing something?

I think what you’re missing is the matter of acceleration. At some point, a higher flap deflection, despite adding lift in principle, lengthens your takeoff roll again because the plane has to work so much harder to get to a speed where it’s capable of flying. You’d be surprised how much of a negative effect a little extra frontal area can have. That’s why short-field takeoffs call for neutral elevator on the runway all the way to vr (as opposed to soft-field takeoffs, where you want to unload the front gear - see below). 
 

I remember when I trained on the C172s. They have a third flap setting at 40 degrees. My instructor only called them “drag flaps”. They were only useful for coming down, not going up. In a go-around, going back to the middle flap setting was the immediate second step after applying power. Otherwise, the plane might simply not climb. 
 

Also, short field and soft field are two different animals in terms of t/o configuration. On a soft field, you want to lighten the load on the gear as quickly as possible and may be content with accelerating in ground effect - or even “hanging it on the prop” if the power-to-weight ratio is favorable enough. That’s very different from a short field, where you might not have that luxury and need to be at vx asap to climb over an obstacle. 

[carusoam]

Welcome aboard Mr. Wilco!

Best regards,

-a-

[Roger Wilco]

On 1/31/2021 at 6:56 PM, carusoam said:

Welcome aboard Mr. Wilco!

Best regards,

-a-

Thank you!

[Will.iam]

On 9/28/2020 at 6:28 AM, midlifeflyer said:

It's sequence based on priority in the go-around,

Full power applied first is standard for every single-engine airplane I have ever flown. It's necessary to arrest the descent and initiate a (weak) climb.  Try retracting flaps and raising gear before adding power on a last second go-around and see what happenes. Better yet, DON'T! !

Retracting flaps from its highest drag configuration to one which enhances the ability to climb out is immediately after, not "later." In most  retracts, including the Ovation manual I am looking at, the initial flap adjustment is even before the gear is raised. 

I was taught a jingle “pickle power boards flaps gear flaps” it has worked in everything i have flown. The pickle is the go-around button but in my mooney i use it it disengage / verify the autopilot is off. Boards are check that your speedbrakes are down flaps is the next notch up or 3 secs on my mooney. Wish it auto stopped at next setting but 3 seconds gets it close without me looking away from outside.  By this time i have a positive rate of climb and gear comes up. The last clean up flaps is after I’m clear of any obstacles immediately in front of me. 

[Ibra]

The correct-answer whatever in AFM/POH 

The short-answer, as everybody said is 1/2 flaps is a fair split between drag/lift flaps 

The long-anwser depends on power (& wind) as well, if your aircraft can climb +1500fpm on full flaps (or VS0 headwind), go-ahead  

The main danger of full flaps takeoff in under-powered aircraft is that if you can't accelerate between VS and VS1 you are pretty much stuck in ground effect like a magnet forever on reservsed controls with no way out, the latter can also happen on go-around even with +300hp if pitch is steep on full flaps just few kts bellow VS0 !

The importance of power becomes apparent when you fly non-turbo in high density altitude, you may have to retract the gear before runway end (my instructor told me to never do that but I leave that advice to 0ft AMSL flying) and if you set lot of flaps by mistake you will never make it

The 2nd most important thing which is always omitted in flap discussions is "the lift off speed and trim forces on given flap setting": TOFF trim forces may not be adequate for full flaps or 1/2, always you have to lift of the aircraft at the right speed, too early or too late just scrambles any advantage of the flaps, I recall on PA28, performance takeoff uses 2 stages of flaps but if you delay liftoff to 65kts on wheels it will just drag the aircraft back with allmost zero advantage compared to no flaps...

In theory,
- You should have full flaps for soft fields initial takeoff run takeoff 
- You should have clean flaps for pavement initial takeoff run takeoff 
- You should have full flaps deployed when you hit the zero lift-off speed (somewhere bellow VS0)
- You should have full flaps retracted when you hit VS1 (never bellow)
- You should have clean claps as you accelerate from VS1 to Vclimb
- You should have best L/D flaps as you hit Vclimb=VX (1/2 flaps?) or clean flaps as you hit Vclimb=VY (0 flaps)

If you do all this with all stick/flap coordination you may get an extra +50ft agl in your performance takeoff compared to setting 1/2 flaps and checking them before banging full power, if flaps get stuck, malfunction or retract too soon you are pretty much dead 

If in doubt and nothing in AFM/POH, the safe-answer is  1/2 !

Edited February 8, 2021 by Ibra

[Little Dipper]

Switching our to the 310 hp with the I0 550 N and prop really increased take off performance.    But even with that my  Ovation at max weight is a runway hog on takeoff.  I can land in a lot less distance than it takes to take off.