When do you retract flaps after take-off?

[pinerunner]

I have an older M20E (1964) with manual gear and Maximum flap extended speed of 100 mph.  I get the gear up soon after liftoff before the IAS gets past 80 mph.  The flaps follow immediately after that before the speed has a chance to get over 100 mph.  Once I'm sure I'm going to clear any obstacles (I haven't needed maximum angle of climb) I want to have the nose just below the horizon for better cooling and so I can see better. That puts the IAS over 100 and gets me great climb rate. From longer runways I just leave the flaps up for simplicity.

[Alan Fox]

7 hours ago, kpaul said:

Trust me in the fact that I am not misguided.  if you were to hold a bicycle wheel/tire <2lbs at the hub and have someone spin it to our take off speed and then rotate it 90 degrees, it would rip itself from your hands.  Spinning objects changing planes have significant torque, hence the reason the engineers include it in checklists to step on the brakes prior to retraction.

You are officially trying to reinvent the wheel.... A good reason to step on the brakes , would be to keep the wheel from spinning water and dirt all over the inside of the wheel well , and to prevent a spinning wheel from hitting anything in the well if there is a maintenance issue...  as far as gyroscopic force , and rotation of the operational plane , if you think that this places excessive forces on the gear , you are not misguided , you are wrong.......

[kpaul]

2 minutes ago, Alan Fox said:

you are wrong.......

You know what they say about opinions....

 

3 minutes ago, Alan Fox said:

A good reason to step on the brakes , would be to keep the wheel from spinning water and dirt all over the inside of the wheel well

This would have happened even prior to lift off.  I have never taken off in a car but get mud and water in the wheel wells.

 

4 minutes ago, Alan Fox said:

as far as gyroscopic force , and rotation of the operational plane , if you think that this places excessive forces on the gear , you are not misguided

Funny, the engineers at Pilatus have a different opinion, I guess they are wrong as well.

[jetdriven]

5 hours ago, Skates97 said:

It is step one in the POH for retracting the gear after take off in my plane. 

Its not in the J POH, as @Bob-s-50 pointed out.  Perhaps they realized it wasnt needed and deleted it. A good idea as time and understanding moves on. There was a thread on BT about this, and someone mounted a camera under the plane. The wheels were, or almost were, stopped as they went into the well. 

[Alan Fox]

2 minutes ago, kpaul said:

You know what they say about opinions....

 

This would have happened even prior to lift off.  I have never taken off in a car but get mud and water in the wheel wells.

 

Funny, the engineers at Pilatus have a different opinion, I guess they are wrong as well.

Yes they are also wrong

 

[jetdriven]

3 minutes ago, kpaul said:

You know what they say about opinions....

 

This would have happened even prior to lift off.  I have never taken off in a car but get mud and water in the wheel wells.

 

Funny, the engineers at Pilatus have a different opinion, I guess they are wrong as well.

For a PIlatus there may be a good engineering reason for it, but again, for this airframe, its not needed. These things take off and land pretty slow, anyway.   10,000 airframes out there and nobody I know has come forward to show an airplane damaged by not applying brakes before retracting the gear.  I see people all the time with these really long checklists, CCGUMPS-S.  really all thats needed is that the gear is down, flaps out of zero, and the mixture and prop set for go-around. Even the 737 and 747 checlklist are 3 items. Speed brake armed gear down and flaps __. 

Keep it simple, use your newfound free time to fly more precisely, or monitor better.

Edited October 17, 2017 by jetdriven

[Mooneymite]

Just now, kpaul said:

This would have happened even prior to lift off.  I have never taken off in a car but get mud and water in the wheel wells.

Having operated off of grass for about 20 years now, I can tell you that the spray pattern prior to retraction is along a very narrow band which includes the flaps and the splash guard in the outer wheel well.  Once retraction begins, the spray pattern changes and the wheel well closer to the fuselage is splattered with whatever was on the tire.

For those not wishing to apply brakes, it seems a slight delay in retraction to allow for normal wheel spin-down would be the solution to keeping "stuff" out of the inboard portion of the wheel wells.

[kpaul]

Just now, Alan Fox said:

Yes they are also wrong

I will inform them during my next meeting with them.

[Alan Fox]

Just now, kpaul said:

I will inform them during my next meeting with them.

I will appreciate that ,   also tell them to stick with Banking , Watchmaking , and Chocolates......  Definitely Chocolates.... They are the best at that

 

[jetdriven]

2 minutes ago, Mooneymite said:

Having operated off of grass for about 20 years now, I can tell you that the spray pattern prior to retraction is along a very narrow band which includes the flaps and the splash guard in the outer wheel well.  Once retraction begins, the spray pattern changes and the wheel well closer to the fuselage is splattered with whatever was on the tire.

For those not wishing to apply brakes, it seems a slight delay in retraction to allow for normal wheel spin-down would be the solution to keeping "stuff" out of the inboard portion of the wheel wells.

Well said, and excellent advice to prevent more trash in the wheel well.

[N6758N]

7 minutes ago, Alan Fox said:

You are officially trying to reinvent the wheel.... A good reason to step on the brakes , would be to keep the wheel from spinning water and dirt all over the inside of the wheel well , and to prevent a spinning wheel from hitting anything in the well if there is a maintenance issue...  as far as gyroscopic force , and rotation of the operational plane , if you think that this places excessive forces on the gear , you are not misguided , you are wrong.......

Excessive forces? Probably not...but still some significant forces none the less. Take a bicycle with a quick release axle type wheel, grab it by the axle and spin it with your hands, now try turning it sideways and report back to us. Now think about a much heavier wheel traveling much faster. Enough force for damage to occur? Probably not, but still some significant force there.

Can't deny that the heavy metal airplanes do this automatically though, probably more to stop a spinning wheel with something stuck on it from damaging the wing/wires, hydraulic lines etc...than to prevent the gyroscopic force from over stressing a part. 

[bonal]

On ‎10‎/‎16‎/‎2017 at 12:03 PM, M20F said:

If you are below flap speed they go up no problem.  I see guys slamming the gear up at times 5’ off the runway.  I don’t think Clarence or me are advocating waiting till 5000’.   This is one of those common sense things where slowing down a bit probably does more for you.  

Until you wait too long and can be a bit difficult to get them stored especially if your not that strong

Not sure where I gave the impression that I or others should be slamming their gear at 5ft AGL. all I said was with the Jbar its tough to get them stored if the speed gets too fast. As for my gear I like to get it up sooner than later cause my airspeed and climb improve as soon as they are out of the way. And for me thats usually about 20ft AGL I like to get as high as possible as soon as possible in case I lose thrust.  I always tap the brakes too following the POH guidlines dont see any reason not to. and to Scott as I said flaps go when pos rate of climb and obstacles cleared.  And as others have said your going to need a long runway to be of any use if you lose power and try to stop with our crappy little brakes and tyres.  No worries mate its all good

[bonal]

58 minutes ago, N6758N said:

gyroscopic force

I like it,  I am going to try an experiment on the same day take off two times in as close to the same way as possible retract the gear at the exact same speed AOA etc and one time tap the brakes and the other letum spin and see if there is any difference in the amount of etffort it takes to put them up

[MyNameIsNobody]

Hi-Larious where this thread direction went....

Wowza.

[HRM]

3 hours ago, MyNameIsNobody said:

Hi-Larious where this thread direction went....

 

Here I'll keep it going.

I'll confess that I hadn't thought about gyroscopic effects (I'm an EE, not an ME) and the video showing the spinning wheels post take-off gave me pause.

But my E is 52 YO and I've owned it for 8 years and have never tapped the brakes pre-retraction.

So I emailed the PO. He owned her for well over a decade and was an Army Air Corps pilot (FWIW). He said:

"Hey Harley, Let me say that my intention was to tap the brakes but often did not remember to do it.  It is a good idea.  I did not ever see any evidence of problems cause by not doing it, but who knows."

Why is this significant? Well, the discussion about this same issue (POA, Beecher's, etc.) point to stress on the gear. Well, for all those years that Ed forgot and the years that I never did do not appear to have affected the gear in any way. I just had the donuts replaced and if anything was amiss my IA would have seen it.

 

Now I am intrigued by the notion of an easier effort on the J-bar. I am a master of the Mooney Nod and perhaps that has clouded the fact that if I tapped the brakes I wouldn't need to do the nod. I'll probably still do it anyway just to activate the pucker-factor on the young buck CFIs that I get every two years for my FR.

 

So, let's see the data. Who's up for calculating the force difference of spin vs non-spin? 

[Hank]

17 minutes ago, HRM said:

So, let's see the data. Who's up for calculating the force difference of spin vs non-spin? 

I thought @PMcClure was going to have his students calculate both ways, to show the difference. 

[Super Dave]

I wonder if Mooney dropped tapping the brakes from the checklist when they went from the 20:1 gear actuator to the 40:1 actuator found in J and later models.

[1967 427]

So back on page one of this string I made comment that the main reason to tap the brakes was gyroscopic affect.  I am an ME and I am willing to take on the challenge of calculating the difference in force reguired.  There are some assumption I will have to estimate; mass, rotational velocity,length of arc of curve.  I will keep these parameters constant in both simulations, the only difference will be the rotational force of the wheel spinning at 70mph.  This force will then be multiplied by 2.  Someone made an estimate of the wheel weight of 12lbs for each wheel, I will use this as one of the variables.

[N201MKTurbo]

6 minutes ago, 1967 427 said:

So back on page one of this string I made comment that the main reason to tap the brakes was gyroscopic affect.  I am an ME and I am willing to take on the challenge of calculating the difference in force reguired.  There are some assumption I will have to estimate; mass, rotational velocity,length of arc of curve.  I will keep these parameters constant in both simulations, the only difference will be the rotational force of the wheel spinning at 70mph.  This force will then be multiplied by 2.  Someone made an estimate of the wheel weight of 12lbs for each wheel, I will use this as one of the variables.

Just make a model in Solidworks, it'll give you the answer.

[1967 427]

SolidWorks will be my stating point, but I do not have access to the add-on utilities to have it spit out an answer.  I will take the solid model an input into a stress analysis software to complete the calculations. 

[Alan Fox]

6 hours ago, 1967 427 said:

So back on page one of this string I made comment that the main reason to tap the brakes was gyroscopic affect.  I am an ME and I am willing to take on the challenge of calculating the difference in force reguired.  There are some assumption I will have to estimate; mass, rotational velocity,length of arc of curve.  I will keep these parameters constant in both simulations, the only difference will be the rotational force of the wheel spinning at 70mph.  This force will then be multiplied by 2.  Someone made an estimate of the wheel weight of 12lbs for each wheel, I will use this as one of the variables.

I will weigh a wheel today , Also take into account , that the wheel will decelerate to zero RPM in about 6 or 7 seconds , due to friction from the bearings / grease , and friction from the brakes.... My estimate would be they likely decelerate to zero RPM in about 6 seconds....

[Guest]

Wouldn't those with manual gear be able to tell us first hand the difference in retraction force with spinning and stopped wheels?  I would think that the difference, if any would be noticeable.

Clarence

[steingar]

2 hours ago, M20Doc said:

Wouldn't those with manual gear be able to tell us first hand the difference in retraction force with spinning and stopped wheels?  I would think that the difference, if any would be noticeable.

Clarence

Airspeed will affect it more than gyroscopic force on a bad day.  Any inclined can run the numbers.  Gyroscopic force on wheels that small and light is almost certainly negligible compared to fighting the wind blast at 80-90 mph.

[Bob_Belville]

• I take satisfaction in @201er's video showing that one of the mains had stopped and that the other was spinning very slowly when the gear started up. I hope Mike can tell us how freely those wheel turn by hand when he can get the plane on jacks. It is obvious to me that the bearings, brake pads and a other factors make our gear a great deal different from a 15 speed bicycle. 
• I have a great deal of Johnson Bar experience. I have almost never applied brakes before retraction but I cannot say that I've ever felt the gyro effect. 
• At the start of the TO roll I move my heels back so that I can toe the rudder without inadvertently getting the brakes. On rotation I automatically am on the right rudder pedal offsetting the P factor. I will try to add the brake tap, it can't do any harm, but you know about old dogs and new tricks. It's not like anyone refers to a written check list at 100' AGL... 

[peevee]

On 10/15/2017 at 6:26 PM, Bob_Belville said:

Agree, a gear up landing on the last 200' of the runway is likely better than running off the end. At least it is safe. I get the gear up very quickly, then the flaps so that I can get the nose down and the speed up to Vy. Then the boost pump to off with an eye on fuel pressure for a few seconds.

besides, the plane probably stops a lot faster with the gear up