When do you retract flaps after take-off?

[steingar]

Just now, EricJ said:

Condensation if the tanks weren't full, possibly.

My first thought, but what I can recall the temps hadn’t changed that much. That’s what made it so odd.  Only that one time, too.

[Bryan]

In my first Mooney purchase, an F, this is what we found upon the ferry flight home.

 

Needless to say, I drained and drained until I had 5-7 cups of fully clean blue fuel. Promptly the o-rings were changed after we got home.

 

Not to completely derail, I retract as soon as positive rate is established to gain as much altitude. Tough to use *runway behind you" or the runway below you.

[flyboy0681]

15 hours ago, Bryan said:

 

 

 

 

I have had the same experience, about two full samplers of clear liquid and it looked just like this. The plane had flown through some precip a few days before and I immediately had our A&P come out to replace the O-rings, no problems since.

[Grandmas Flying Couch]

On 10/15/2017 at 6:14 PM, Bob_Belville said:

What a couple of us are saying is that we'd rather get the gear up quickly., even with some runway in from of us. If the engine should then quit we'd be willing to do a belly landing. Roll out is very short, injuries are unlikely. Props can be replaced, engines can be torn down, it's only money and most of it is the insurance company's. Beats landing on tires and plowing into trees, a ditch, a fence, or a ravine.  

I say if the engine quits in the 10 second window where I could have landed back on runway, That means I'm pitch up with low airspeed, I don't want the drag from the gear, and my electric gear extends in 3-4 seconds.  I think usable runway is an old dangerous practice that tries to save the plane over the humans.  You are VULNERABLE during early climb phase, gear up or down, I want to get out of the phase as quickly as possible.  

If the engine quits after pos rate gear up, I'll get nose pointed down and trimmed and then drop gear for extra drag (3-4 seconds), or not if there's no time, then I call insurance company.  

Leaving gear down compromises every single takeoff for the one in a million you may be able to save your belly/prop and it compromises your chances in my opinion. 

Most importantly it looks cool 

On 10/15/2017 at 5:43 PM, Mooneymite said:

I think bent prop tips are a small price to pay for a quick, early gear retraction and the attention of all the gawkers.

 

 

[aaronk25]

Scott flaps up at 100mph. It’s a good speed where the angle of attack after a full flap retraction in one motion (going from take off flaps to flaps up all at once) won’t give excess angle of attack (for view and drag). Wheels up at positive rate of climb then looking for 100mph. 90 seems to slow and 110mph and flaps are starting to create quite a bit of drag. Some of these guys who are flying more than 200hp our front don’t notice this as much and seem to end up retracting at higher speeds if left to the seat of the pants “feel”.


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[Wildhorsesracing]

I did a few touch and go's today and found the following with my '62 C - #1 is my normal routine.  The runway is 5500 ft long, 3 mph winds, 29.93 hg, 608ft msl.

1) Rotate at 60mph, gear up at 80mph, Flaps up at 100ft agl~90mph

       - at 1000ft agl by the end of the runway

2) Rotate at 60mph, Press brakes, gear up at 80mph, Flaps up at 100ft agl~90mph

       - no noticeable difference from #1

3) Rotate at 60mph, Flaps up at 100ft altitude ~80mph, gear up at ~105mph when no more usable runway

       - much harder to get the gear up and only 700 ft agl by the end of the runway

4) Rotate at 60mph, Flaps up at 100ft altitude ~80mph, Press brakes, gear up at ~105mph when no more usable runway

      - much harder to get the gear up, no difference from #3

I repeated each one to make sure it wasn't an anomaly.  I think the wheels had already stopped in #4 since it was 3500 ft of the runway before I was high enough to not be able to use any of the leftover runway.

I think I might start tapping the brakes to keep the wheel wells cleaner, but it was clear that getting the gear and flaps up early improved the climb rate, and as they say, altitude is precious when the engine quits.

 

[Hank]

Wow, i generally rotate flapless at 70, unless I'm heavy and use 75 mph with Takeoff flaps. Apparently the Owners Manual for C models has several versions, there are significant procedural differences between my 1970 one and the last one covering 76-78 models.

I don't have an altitude or speed for cleaning up, just gear goes up once I'm in "good control" with positive rate, and flaps go up when I'm looking down on the obstacle whose clearance worried me. My initial climb is at Vx (85 mph) to clear obstacles, then relax to Vy up to cruising altitude (100 mph minus altitude).

Edited October 26, 2017 by Hank

[JohnB]

On 10/15/2017 at 12:43 PM, PTK said:

Flaps increase lift and add drag. Takeoff flaps increase lift to get the airplane off the runway quicker while adding minimal drag. For more than take off flaps the drag increase overwhelms any lift benefit. As speed increases so does lift and the need for flaps diminishes.

Therefore I'm not in a great hurry to clean up takeoff flaps. A white arc with a Vfe of 115 KIAS is very generous. I retract them when speed is well on its way and has safely increased in the climb. Typically around 1000 feet or so.

+1 on your technique PTK, this is what I do. For me, because on takeoff, I want the highest altitude possible in the shortest distance away from the airport, so in case I ever had an engine out at an altitude I could potentially make "the impossible turn", that would be an additional option and the additional lift and increased drag by takeoff flaps would help to get higher at a shorter distance away.  I retract gear when I can no longer make a landing straight ahead on the runway.

As for the brakes after takeoff, this part may be an OWT, but I heard that tapping your brakes after takeoff also helps save your tires as some wheel retractions in some airplanes, the wheel can touch something in the underbelly and put wear on your tires, which would obviously not be an issue if your wheel is not spinning. 

[Bob - S50]

9 hours ago, JohnB said:

+1 on your technique PTK, this is what I do. For me, because on takeoff, I want the highest altitude possible in the shortest distance away from the airport, so in case I ever had an engine out at an altitude I could potentially make "the impossible turn", that would be an additional option and the additional lift and increased drag by takeoff flaps would help to get higher at a shorter distance away.  I retract gear when I can no longer make a landing straight ahead on the runway.

As for the brakes after takeoff, this part may be an OWT, but I heard that tapping your brakes after takeoff also helps save your tires as some wheel retractions in some airplanes, the wheel can touch something in the underbelly and put wear on your tires, which would obviously not be an issue if your wheel is not spinning. 

Something you might consider.  If you want the most altitude possible and still be as close to the airport as possible, you might want to try making a V_x climb.  Check your POH but I suspect that is at a very slow speed with flaps up.

Personally, I would prefer as much energy as possible which implies cleaning up as quickly as I can safely do so.

[JohnB]

14 hours ago, Bob - S50 said:

Something you might consider.  If you want the most altitude possible and still be as close to the airport as possible, you might want to try making a V_x climb.  Check your POH but I suspect that is at a very slow speed with flaps up.

Personally, I would prefer as much energy as possible which implies cleaning up as quickly as I can safely do so.

Yes, I intentionally didn't mention airspeed climbing out, as I didn't want to start that Vx Vy climbout debate for which there is never one definitive answer to!  I agree with you Bob, I don't do Vx unless I have to because of obstacles as would be quite slow. I live in a very congested area where off field low altitude landings would be tough. So consider this for a moment,  given a certain time (just say 1 minute) I would presume if you were to climb at Vy, with takeoff flaps, vs Vy without takeoff flaps both for 1 minute, you might be higher and slightly closer to your airport with takeoff flaps due to increased lift with slightly increased drag at the same time.

After the gear come up, I don't touch anything until I am above that critical altitude that I believe I could make a safe return to the airport then flaps come up as I would like that slightly improved wing lift if I were ever forced to do that turn at a solid airspeed that wont stall a wing. (this would be a much higher airspeed if you were completely clean with the steep turn that would be required to return) but both are possible to do!

[Bob - S50]

9 hours ago, JohnB said:

Yes, I intentionally didn't mention airspeed climbing out, as I didn't want to start that Vx Vy climbout debate for which there is never one definitive answer to!  I agree with you Bob, I don't do Vx unless I have to because of obstacles as would be quite slow. I live in a very congested area where off field low altitude landings would be tough. So consider this for a moment,  given a certain time (just say 1 minute) I would presume if you were to climb at Vy, with takeoff flaps, vs Vy without takeoff flaps both for 1 minute, you might be higher and slightly closer to your airport with takeoff flaps due to increased lift with slightly increased drag at the same time.

After the gear come up, I don't touch anything until I am above that critical altitude that I believe I could make a safe return to the airport then flaps come up as I would like that slightly improved wing lift if I were ever forced to do that turn at a solid airspeed that wont stall a wing. (this would be a much higher airspeed if you were completely clean with the steep turn that would be required to return) but both are possible to do!

You sure make me think.  If I'm at V_y in both cases, although the pitch might be slightly different, the groundspeed will be essentially the same in either case.  So in any given amount of time I will have traveled the same distance.  The question then becomes, do I get to altitude more quickly if I do that with flaps up or down?  Theoretically, climb rate is determined by excess power.  Leaving the flaps down creates more drag which leaves less excess power which means a slower climb rate.  And, with flaps down, you'll need a lower pitch to generate the required lift so your flightpath will be a little shallower.  So in theory, if you are climbing at V_y regardless of configuration, I would think you would actually be closer to the airport with the flaps up.

If our climb rate at V_y was really better with flaps down, that's what the POH would tell us.

On the other hand, if you were to climb at V_y and clean or at V_x with takeoff flaps then that might be a different story.

Why don't you go try it?  Do two takeoffs, one clean and one dirty.  Use a standing start full length and use your flaps down technique.  Be sure to maintain V_y in the climb and see what you are over when you get to 1000'.  Immediately go back and land.  Do the exact same thing but this time get the flaps up as soon as you safely can and then climb at V_y to 1000' and see where you are.  Let us know what you find.

[bradp]

On 10/16/2017 at 10:25 AM, Bob_Belville said:

wheel would only coast about one revolution when spun by hand.

Re the tightening of the axle nut- my IA tells me that an over torqued axle nut is a common cause of early wheel bearing retirement.  Properly torqued axle nuts also make the plane more manageable to move by hand. 

I once got board on a car ride and verified by knowing the size of my tires, the engine rpm, and gear ratio, that I was in fact traveling at 60 mph... should I have been an engineer in an alternative life?  

I've had significant water issues twice.  Once when I was tied down outside and the plane was brand new to me.  Inspection of the inner O ring indicated it needed to be replaced.  The second time was when I learned I don't trust anyone to fuel my plane without me present.  Line boy jammed the cap on tilted and got several ounces of water when it rained.  In that case, I drained the water, grabbed the wing tip and shook the plane back and forth and up and down, let water migrate (i.e. wait 5-10 min), drain, shake, wait, drain; I also took off and landed on my known good tank.  

Same thing after some recent fuel tank patch repair - although we did everything possible to avoid contamination of old flecks of fuel tank sealant, still found a few flecks after the plane was released.  Drain, shake, wait and I didn't fly on (or more importantly take off or land on) that tank until I was confident I wasn't going to get a contamination issue.  

[JohnB]

12 hours ago, Bob - S50 said:

You sure make me think.  If I'm at V_y in both cases, although the pitch might be slightly different, the groundspeed will be essentially the same in either case.  So in any given amount of time I will have traveled the same distance.  The question then becomes, do I get to altitude more quickly if I do that with flaps up or down?  Theoretically, climb rate is determined by excess power.  Leaving the flaps down creates more drag which leaves less excess power which means a slower climb rate.  And, with flaps down, you'll need a lower pitch to generate the required lift so your flightpath will be a little shallower.  So in theory, if you are climbing at V_y regardless of configuration, I would think you would actually be closer to the airport with the flaps up.

If our climb rate at V_y was really better with flaps down, that's what the POH would tell us.

On the other hand, if you were to climb at V_y and clean or at V_x with takeoff flaps then that might be a different story.

Why don't you go try it?  Do two takeoffs, one clean and one dirty.  Use a standing start full length and use your flaps down technique.  Be sure to maintain V_y in the climb and see what you are over when you get to 1000'.  Immediately go back and land.  Do the exact same thing but this time get the flaps up as soon as you safely can and then climb at V_y to 1000' and see where you are.  Let us know what you find.

Hmm I might actually do that as I was planning on doing some to & landings soon. I guess I would have to keep same airspeed for the same time and track what altitude I’m at and distance from airport with both takeoff flaps and no flaps to see if there’s a difference! Might be fun.

but either way, I would still use takeoff flaps until I am above my critical altitude as I do want that extra lift on the wing to reduce the chance a stall in a steep turn. 

[Hank]

Flew three legs today, 2 people, fuel varied from half to full. Used at least Takeoff flaps on each landing, but all three departures were unusually fast at ~110 mph and 1000 fpm. All takeoffs were Flaps Up.

The way I see it, unless I've forgotten my basic physics, adding drag to an airplane will not make it go faster or higher, but removing drag can do both. 

[DaV8or]

I don't use the flaps or the gear handle. If you leave the flaps up, you never have to think about them. Same goes for the gear and the added benefit is, you'll never have a gear up landing. The red and blue knobs are annoying too. I leave those all the way forward. Nothing good can come from them.

My car has a throttle and a brake. That's all my airplane needs too. I've heard about cowl flaps, but I haven't found them yet. It's not cabin air is it? Anyhow, I don't see the point. Why would the cowl need more lift? Do they help you go up faster? Is that how you land in a nose high attitude, with full cowl flaps? 

Seriously, too much work. If it gets off the ground and flies with just the throttle, why complicate things?

 

 

[HRM]

11 hours ago, DaV8or said:

Seriously, too much work. If it gets off the ground and flies with just the throttle, why complicate things?

I agree. Flaps are a tool to modify flight based on conditions. Sometimes you want them, more often not (at least for me). Good to have them, should be tested at run-up, but used as needed.

Oh, and let me add that the flaps on the Mooney, infinitely variable and instantly retractable with a (tiny) lever--are a near perfect design (IMNSHO).

Edited October 28, 2017 by HRM
Added comment about the perfection of the flaps.

[Hank]

2 hours ago, HRM said:

I agree. Flaps are a tool to modify flight based on conditions. Sometimes you want them, more often not (at least for me). Good to have them, should be tested at run-up, but used as needed.

My Owners Manual agrees with use what is needed for flaps, but doesn't mention testing them at runup . . . .

[HRM]

10 hours ago, Hank said:

..but doesn't mention testing them at runup . . . .

I think the checklist says set them, I just check 'em. 

[Skates97]

Mine says to "inspect the flaps" on the preflight walk around. My process is to put the flaps down before I start and check them as I go around the plane. After I pull the plane out one of the steps before starting it is flaps up. This lets me make sure that they go down properly and hopefully if there is a leak in the system allowing them to retract then it will show up by the flaps not staying extended throughout the preflight process. Also I am able to watch them retract prior to the start up.