How long do you wait to retract flaps on takeoff?

[bnicolette]

For me, it's positive rate of climb with no more usable runway - Gear Up. Gear up, 400' AGL and clear of obstacles - Flaps Up.

You forgot v2 + 20 ;-)

[jlunseth]

Gear up when out of usable and definitely a positive rate of climb. Flaps after gear if I have used flaps for takeoff.

[WardHolbrook]

You forgot v2 + 20 ;-)

I was talking propeller retracts. Actually in the Falcon 900 it's V2 + 25, but what's 5 knots among friends?   

[DAVIDWH]

Any one have any experience with this one?

 

Not sure if this came from the poh or a blog, but I remember reading that "no flap take offs in long body Moonies

 

increase the propensity for dragging the tail.  Is this possible?

[Super Dave]

Any one have any experience with this one?

Not sure if this came from the poh or a blog, but I remember reading that "no flap take offs in long body Moonies

increase the propensity for dragging the tail. Is this possible?

I know of at least one Ovation that had a tail strike that required repair work.

[Marauder]

Any one have any experience with this one? Not sure if this came from the poh or a blog, but I remember reading that "no flap take offs in long body Moonies increase the propensity for dragging the tail. Is this possible?

At the New Garden fly-in we had a long body there. That tail is a lot lower than I even imagined. I think 201er was talking to the owner about that possibility. It sure looks possible.

[carusoam]

The tail is a lot longer....but,

Somebody ground the tail tie down ring on my M20C before I got it...

A high nose attitude would be required to drag either the R or the C...

POH says set flaps to T/O position 10deg....

I searched the POH for other indications of ways to drag the tail, but I didn't see anything other than Normal procedures. Soft field has it's own performance chart, but procedures are the same.

All things are possible, I guess...

Keep in mind, I am not an expert in anything aviation related....just reading the POH.

Best regards,

-a-

[Scott Aviation]

I typically do 1000ft agl retract flaps, switch off boost pump. Climbing at 700ft/minute at 90-100kts is typical. I really don't like the idea of dumping flaps too early, I find the plane kind of mushes for a second before I retrim. Anyone else agree or think my technique is bad?

[Jamie]

This paper (attached) studies the use of flaps to reduce take off distance.  In their words "substantial reductions in the distance required by an airplane to take off and climb to a distance of 50 feet should be possible through the use of flaps".

 

Three most useless things in aviation: Sky above you, runway behind you and the gas you left on the ground.

 

So, obviously, using less runway is good. But I don't see any point in waiting to get the flaps up.  The paper says they reduce runway used, it does NOT say they increase climb rate. Once you're off the concrete and over the obstacle, they're not useful anymore... they're just drag when what you need now is airspeed (cruise climb).

 

Personally, me raising take off flaps has more to do with when I have a few spare cycles and can safely divert attention to retracting them rather than any performance based criteria.

 

 

 

 

 

 

use_of_flaps_on_takeoff.pdf

[Seanhoya]

Gents - I am no aerospace engineer, but my understanding was that flaps increase the angle of climb, but don't necessarily increase the rate of climb.  In fact, they increase drag, thereby decreasing performance.  Am I off-base with this comment?

 

My perspective is that if you leave the flaps extended longer, you will be higher, closer to the field, should you have a problem.  On a cold day in Monterey, I am 1000' AGL by the end of the runway.  On a hot day, it might only by 500-600' AGL.  Leaving flaps extended longer improves one's chances to make the fabled 180 degree turn and plant it on the runway (in the vicinity of the runway).  Or not?

 

To me, with only one engine, altitude is life.  That is why at home, I leave flaps extended until 800' MSL - because I think I can make the turn back to the field at this point.  But my M20G isn't exactly a rocket in the climb - I think it is just slightly underpowered, which is why the F model was and is more popular....

[201er]

That is why at home, I leave flaps extended until 800' MSL - because I think I can make the turn back to the field at this point.  But my M20G isn't exactly a rocket in the climb - I think it is just slightly underpowered, which is why the F model was and is more popular....

Although I agree with most of your points, in this case I don't think this is valid. If the engine is destined to quit, it will quit X seconds after takeoff regardless of flaps or not (some might argue sooner with flaps because higher angle means less cooling). I think you're right that your climb angle is effectively steeper with flaps but this takes extra time. Like gear, if you can retract flaps fairly soon, that is less energy you're going to waste on drag.

 

Actually I think (and am pretty sure) that FPM is higher with flaps retracted. However, you're right that with flaps extend (especially with headwind) you will stay closer while you get higher. When it comes to the impossible turn, being close probably doesn't help. As for being higher and/or faster I'd suspect it would be with flaps retracted.

[John Pleisse]

1000 agl. A 10KT slower plane if you lose the engine on t/o. Workload spread evenly. Less fuss close to the ground. The first time I flew an O, I felt as if I had less ability to flare. For the gentleman who had the thread about Mooney specific training, a great quirk of all J's and post J's is the flap motor and trim motor operate at the same speed. Flap retracts aren't even felt.

[gsengle]

I've certainly done this - but that was when I was waiting longer to retract.  For me it is clear of obstacles AND sufficient airspeed.  I don't want to retract em when I'm below maybe Vx - as a practical matter, gear is up with pos rate and at least 50 feet up or so, and then when I can nose forward enough to get to 85 or 90 knots, up come the flaps.  This is pretty quick.  I figure I will climb the fastest by getting clean and hitting Vy, and the goal is to get as far from the ground as fast as possible in the first 1000 feet or 2, in case of engine failure.

 

g

 

 

Nobody as of yet has mentioned my problem... retracting them only after asking myself why I'm not seeing any speed. This usually happens about 15 minutes into the flight.

[gsengle]

Disagree per my previous post - when my Ovation flaps come up, I feel it.  From roll to clear of obstacles, you're minimizing roll and distance laterally to obstacle - so flaps down targeting Vx.  As soon as youre past the obstacle, your goal is to get away from the ground as FAST as possible, not as close to your start.  So you nose over a bit for Vy and maximize your rate of climb until you are high enough to have reasonable gliding options.  This means also bringing up the flaps because your best rate of climb comes in a clean configuration.

 

g

 

1000 agl. A 10KT slower plane if you lose the engine on t/o. Workload spread evenly. Less fuss close to the ground. The first time I flew an O, I felt as if I had less ability to flare. For the gentleman who had the thread about Mooney specific training, a great quirk of all J's and post J's is the flap motor and trim motor operate at the same speed. Flap retracts aren't even felt.

[Parker_Woodruff]

Positive rate of climb, clear of any pressing obstacles, gear up, Vy, Flaps up.

[Super Dave]

Flaps degrade both rate AND angle of climb.

[Parker_Woodruff]

Flaps degrade both rate AND angle of climb.

Except their retraction each degrades performance for a short time.

[Super Dave]

Except their retraction each degrades performance for a short time.

I agree; I was responding to earlier posts that were wondering if flaps helped climb rates/angles. I'm a no flaps guy, unless required for runway length or close in obstacles. If I'm using TO flaps, I wait till all obstacles cleared for the reason you mention.

[Seanhoya]

Really, this should be a question about stall speeds, not flaps or no-flaps.  In general, I prefer not to climb at 80 MPH if I don't have to - it's not good from a cooling perspective for my M20G.  But in the runway environment, when angle of climb is important, I choose to climb at 80 MPH with flaps because flaps decrease stall speed, thus giving me an added margin of safety if I need to maneuver, which is also a real possibility in the runway environment. 

 

80 MPH without flaps feels mushy, and the stall speed is higher - meaning that you are closer to a stall.

 

80 MPH with flaps is more solid and the stall speed is lower - meaning that you have an added margin of safety.

 

Which regime do you want to hang-out in when close to the ground?

 

Just a thought...loose the cannons!

 

BTW - Yes, in pure aerodynamic terms, flaps may lower angle of climb, but as a second-order effect, they allow one to climb at a lower airspeed - this INCREASES angle of climb, for a net increase in angle of climb, but decrease in rate of climb.  From what I understand, also, the type of flaps greatly influences the net results in terms of rate and angle of climb.

[flyboy0681]

5 minutes ago, Hyett6420 said:

I have a simple rule it goes like this:-

1.  rotate

2.  positive rate of climb established

3. speed still increasing to best rate of climb

4. Runway no longer able to land on, retract gear

5. Check positive still established

6  300 feet agl retract flaps

7. check positive still established 

8. 500 feet agl reduce to 25/25

9 check positive still established. 

Hey presto. 

Uh oh, that 25/25 is going to open up Pandora's box.

[carusoam]

FlyBoy,

That's where people start curling up and screaming...

'Hey! You can keep climbing at full throttle'

Some level of flexibility is good.

Flying with a silent pilot leaves a lot of interpretation of what is going to happen next.

A pilot that verbally mediates the memorized checklists prior to every step is strangely comforting.

Having the pilot on short final not saying anything as the ASI unwinds can be a little unnerving.

The final thing that leaves me comfortable flying with a Mooney pilot.  They haven't crashed a plane that I know of, yet...

Best regards,

-a-

[Raptor05121]

I normally do a simple "window" procedure when flying the Cherokee....400AGL, flaps up (if used which is rare) and 1000AGL fuel pump off.

With the Mooney, my plan is: off the runway, positive rate, gear up. Flaps up 400AGL, pump off 1000AGL. As for power, I'm still on the fence, but IMHO, I think leaving (at least throttle) firewalled is what I will do. I've got absolutely NO interest in bringing back power at 500AGL. Complete idiocy.

[gsengle]

Ovation. Positive rate, bring the gear up. Vx until clear of obstacles. Nose over a bit and before I hit end of white arc raise flaps and continue climbing at Vy through maybe 1500, then speed to 125kts for better cooling and visibility still climbing at better than 1000fpm.

Get those flaps out asap after you're clear of things they only add drag!

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[ArtVandelay]

2 hours ago, gsengle said:

 

Get those flaps out asap after you're clear of things they only add drag!

 

I thought 15 degree flaps add lift without much drag, and vice versa for full flaps?

i drop to 2500 rpm for noise abatement...

[gsengle]

Any flaps is drag. More lift is by definition drag.

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