Tapping brakes on gear retract?

[r0ckst4r]

Just a random poll for you guys.  I was watching some videos of Vision Jets preparing for when I win the lottery  and just happened to notice that the CFI in one video gave the instruction to tap the brakes after take-off before retracting the gear.  I've heard of this before to stop the wheels from rotating before they are stowed but to be honest in my 5 years of flying my O I've never done it nor is it mentioned anywhere in the POH.  Any of you guys tap the brakes on take-off?  Is this a "how I learned it" dependent thing or maybe just more aircraft specific?   Haven't looked at the Vision Jet POH yet lol.

[LANCECASPER]

On 1/11/2024 at 8:48 AM, r0ckst4r said:

Just a random poll for you guys.  I was watching some videos of Vision Jets preparing for when I win the lottery  and just happened to notice that the CFI in one video gave the instruction to tap the brakes after take-off before retracting the gear.  I've heard of this before to stop the wheels from rotating before they are stowed but to be honest in my 5 years of flying my O I've never done it nor is it mentioned anywhere in the POH.  Any of you guys tap the brakes on take-off?  Is this a "how I learned it" dependent thing or maybe just more aircraft specific?   Haven't looked at the Vision Jet POH yet lol.

I’ve heard about it for years but in thirty years of flying Mooneys I’ve never done it once. Not that it’s going to hurt anything, but I’ve never heard anything that’s convinced me to do it. I’m more concerned about good rate of climb (am I going to clear any obstacles), gear up,  flaps up, engine instruments, etc.

The last Mooney POH, that I can find, that says to do that was the F model. (http://www.monticellofc.org/aircraft/N3275F POH Complete - Reduced.pdf)

Either Mooney realized that it wasn't necessary altogether or they changed something after that model. 

[Ibra]

I don’t think it matters that much in Mooney (other than inconvenient noise if you have very sensitive ears), it’s like “positive rate of climb gear up” callout in Mooney, it always made me laugh as it’s easy to know when wheels have left ground in small pistons? especially, if you already flew old aircraft that were certified without VSI indicators 

“Positive rate of climb, gear up” make sense in aircraft where at rotation you already climbed 100ft agl from pilot cockpit while aircraft wheels are still on ground, in other words, you don’t know if you are flying above the ground or not without looking at VSI > 0

 

 

Edited January 11, 2024 by Ibra

[Greg Ellis]

The Owner's Manual for my 1963 C model (more like a pamphlet, really) does say to Apply brakes to stop wheel rotation prior to retracting the gear.  I have never consciously done this.

[201er]

14 minutes ago, r0ckst4r said:

Just a random poll for you guys.  I was watching some videos of Vision Jets preparing for when I win the lottery  and just happened to notice that the CFI in one video gave the instruction to tap the brakes after take-off before retracting the gear.  I've heard of this before to stop the wheels from rotating before they are stowed but to be honest in my 5 years of flying my O I've never done it nor is it mentioned anywhere in the POH.  Any of you guys tap the brakes on take-off?  Is this a "how I learned it" dependent thing or maybe just more aircraft specific?   Haven't looked at the Vision Jet POH yet lol.

Yes. I have made it a habit to tap the brakes after every takeoff in my Mooney after seeing what’s happening with my wheels in this video of one of my takeoffs a while ago:

2:35 into the video.

I was surprised how long the right wheel was spinning after retraction.

There may be some wear from loading from gyroscopic precession while swinging spinning wheels. But more importantly it may be spraying mud/debris into the wheel wells. Particularly after parking on grass (think Oshkosh). So, it’s become SOP not to think about differentiating when the wheels are clean vs not. I tap the toe brakes while reaching for the gear lever.

[Mac80]

I have tried it. Seems to cause a little variation in climb. Maybe because I am not even with pressure and rudder causes that. Where I heard it can be important is to get slush off brakes that may have accumulated during taxi or takeoff. Would avoid frozen brakes when landing. Also heard you do not want to retract while the wheels are still spinning so I wait and don’t retract immediately . Seems like I can till when they stopped  spinning.

[Hank]

18 minutes ago, Greg Ellis said:

The Owner's Manual for my 1963 C model (more like a pamphlet, really) does say to Apply brakes to stop wheel rotation prior to retracting the gear.  I have never consciously done this.

Same for my '70 model.

But I almost never use the brakes. I also don't reduce RPM, just retract gear (and flaps, when I use them) and establish initial climb at Vx to clear obstacles before going to Vy.

[Shadrach]

1 hour ago, LANCECASPER said:

I’ve heard about it for years but in thirty years of flying Mooneys I’ve never done it once. Not that it’s going to hurt anything, but I’ve never heard anything that’s convinced me to do it. I’m more concerned about good rate of climb (am I going to clear any obstacles), gear up,  flaps up, engine instruments, etc.

Have you ever rotated the axis of a large spinning gyro 90°?  The equipment will tolerate it, but it is not a kind thing to do to the wheel bearings and gear bushings. I'm sure you had a physics teacher do the bicycle wheel gyro demonstration. A Mooney wheel acts the same except for it's spinning at 1,300ish RPM.

My POH also recommends wheel rotation be stopped.

[N201MKTurbo]

I think our gear is strong enough to take any precession loads. You could tighten your wheel bearings by one notch. That would slow them down.

[Shadrach]

4 minutes ago, N201MKTurbo said:

I think our gear is strong enough to take any precession loads. You could tighten your wheel bearings by one notch. That would slow them down.

Without question, we'd be in big trouble if it wouldn't. Nevertheless, it's an easy load to eliminate.

[N201MKTurbo]

8 minutes ago, Shadrach said:

Without question, we'd be in big trouble if it wouldn't. Nevertheless, it's an easy load to eliminate.

I think I subconsciously do it. I will have to check next time I fly.

[201Mooniac]

I was taught to do it when I first checked out in an arrow in 1993 and I've done it ever since.  I have no idea if it does anything but it doesn't seem to hurt anything either.

[A64Pilot]

48 minutes ago, N201MKTurbo said:

I think our gear is strong enough to take any precession loads. You could tighten your wheel bearings by one notch. That would slow them down.

Wheels are nothing, think about the prop. I quit spinning a tailwheel around quickly when I gave that a thought, yet apparently it hasn’t caused any harm. Some of our models had 117” props and if it was a Garret it was turning at high RPM. Image what an aerobatic airplanes prop and crank go through.

Way back years ago my Father would hear a ticking noise on retraction, turned out it was the valve stem hitting something on his C model, I guess it had an improper tube?

If you want to stop wheel rotation I don’t see how it could hurt, but I’m not going to worry about it, but if I hear a ticking I know where to look  

[Immelman]

That's an interesting thought on being kind to the wheel bearings on the mains. Hard to stop the nose gear though, but its being rotated back parallel to the axis of rotation so..... maybe a detour back to basic physics class is in order for that thought experiment!

FWIW in transports the brakes are typically applied automatically to stop MLG rotation. No brakes on the NLG, they're stopped by snubber pads in the wheel well which makes an interesting noise for a few seconds.

Edited January 11, 2024 by Immelman

[EricJ]

It's not at all hard on the brakes or gear to tap the brakes momentarily to stop the wheels, and it'll eliminate any precession stress on the bearings or other gear components.   I agree that the stress due to the precession is probably well within the capabilities of the bearings and other components, but it's also a stress that's easy to eliminate at nearly no cost.

I do it by habit.   Feels weird if I don't. 

[r0ckst4r]

Interesting that tapping the brakes was in the manual for older models but has been completely removed now for the newer models.  They must have felt at some point that it was no longer significant.

[PeteMc]

9 minutes ago, r0ckst4r said:

Interesting that tapping the brakes was in the manual for older models but has been completely removed now for the newer models.  They must have felt at some point that it was no longer significant.

Be curious if there is any "auto breaking" applied by the way the break lines move or because of some other change they made in the newer models? 

 

[Shadrach]

17 minutes ago, PeteMc said:

Be curious if there is any "auto breaking" applied by the way the break lines move or because of some other change they made in the newer models? 

 

Not for my bird. Wheels spin freely when retracted.

 

[N201MKTurbo]

Fun with my trusty TI-34

Assuming a tire diameter of 17.5”

50 MPH = 960 RPM

60 MPH = 1160 RPM

70 MPH = 1344 RPM

80 MPH = 1536 RPM

[Shadrach]

5 minutes ago, 1980Mooney said:

The debris would have been thrown off long before gear retraction.  Based upon Goodyear spec - 6.9 inches static load radius for the mains - the wheels are spinning at about 2,000 rpm at liftoff.  The nose wheel is spinning at about 2,400 rpm.  Of course if inflation is low they are spinning even faster.

I think your numbers are off a bit, but you probably lift off faster than my 75-80mph. The specified diameter range for Goodyear 5.00X5 and 6.00X6 is 13.65-14.2" and 16.8-17.5" respectively.

[Hank]

1 minute ago, Shadrach said:

I think your numbers are off a bit, but you probably lift off faster than my 75-80mph. 

My Owner's Manual says to lift the nose at 65-75 mpg, so I usually split the difference and pull at 70 mph, unless I'm heavy or the wind has significant gusts. So a little over 1300 RPM. Not too bad.

[N201MKTurbo]

We are all just nerds at heart….

[Hank]

Just now, N201MKTurbo said:

We are all just nerds at heart….

BSME, MSE. Guilty!

[ArtVandelay]

I tap the brakes before retracting the gear, as I was taught.

[A64Pilot]

55 minutes ago, PeteMc said:

Be curious if there is any "auto breaking" applied by the way the break lines move or because of some other change they made in the newer models? 

 

I would hope not, I don’t want anything that could “auto brake” because my luck it would at high speed on the ground.