Tapping brakes on gear retract?

[A64Pilot]

1 hour 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.

Best answer I can give is the truth changes, like they had you reducing RPM by quite a lot, I assume that’s gone too?

As someone who has written one or two POH’s I can attest that a lot of things make it into a POH because the person writing it thought it was a good idea, without any data to support it.

[Shadrach]

6 minutes ago, Hank said:

BSME, MSE. Guilty!

I was a late blooming nerd, to old to acquire fancy nerd credentials...

[A64Pilot]

4 hours ago, Ibra said:

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

 

 

I think the load on the gear actuator is higher on retraction the higher speed gets. That’s why I get mine when I’m sure I won’t settle back to the runway, “positive rate”

I’m paranoid about that actuator and baby it.

On other aircraft I leave them down until landing on the departure runway isn’t possible thinking if the engine quits I’ll just land straight ahead.

[Hank]

1 minute ago, Shadrach said:

I was a late blooming nerd, to old to acquire fancy nerd credentials...

My two degrees were completed 23 years apart . . . . It's not too late for you. See if work will pay for it like they did my MSE.

[PT20J]

According to an old Beechtalk post, John Deakin claimed the practice is likely from old WW II aircraft manuals. https://www.beechtalk.com/forums/viewtopic.php?f=2&t=59754

Personally, I don’t bother. I already have enough to think about on takeoff 

[Shadrach]

1 hour ago, A64Pilot said:

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.

The prop and the crank, think about those little 1/4" AN4 bolts that are holding the engine mount to the airframe 3' way from that huge spinning gyro.

[CChris]

Maybe it is just me, but I feel the J Bar in my C is lighter to operate if I tap the brakes before retracting the gear...

[A64Pilot]

13 minutes ago, Shadrach said:

The prop and the crank, think about those little 1/4" AN4 bolts that are holding the engine mount to the airframe 3' way from that huge spinning gyro.

Four 1/4” bolts held the landing gear (skids) on an OH-58 helicopter, procedure to determine Ng at when the bleed valve closed was to have several people stand on the skids and the pilot pull collective until it closed, guys standing on the outside would watch it.

When I made SGT I had us stacking tool boxes on the floor in back and on the back seat, If one of those bolts broke or pulled the threads out it would have been a dynamic roll over and I think us standing on the skids would have been chopped up.

[A64Pilot]

16 minutes ago, CChris said:

Maybe it is just me, but I feel the J Bar in my C is lighter to operate if I tap the brakes before retracting the gear...

Who knows maybe?

https://en.wikipedia.org/wiki/Magnus_effect#:~:text=The Magnus effect is an,the object is not spinning.

[LANCECASPER]

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.

Thankfully once the earth’s crust finally cooled, they eliminated that from the checklist




Sent from my iPhone using Tapatalk

[EricJ]

1 hour ago, N201MKTurbo said:

Fun with my trusty TI-34

...

 

1 hour ago, N201MKTurbo said:

We are all just nerds at heart….

Real nerds use HP calculators. 

Reverse Polish notation FTW! 

[MikeOH]

7 minutes ago, EricJ said:

 

Real nerds use HP calculators. 

Reverse Polish notation FTW! 

HP-15C for the win!

(Still use mine daily)

[Shadrach]

On 1/11/2024 at 2:05 PM, PT20J said:

According to an old Beechtalk post, John Deakin claimed the practice is likely from old WW II aircraft manuals. https://www.beechtalk.com/forums/viewtopic.php?f=2&t=59754

Personally, I don’t bother. I already have enough to think about on takeoff 

Wow, they went 9 pages. I thought we at Mooneyspace were the best when it comes to bludgeoning deceased equine.

[Hank]

11 minutes ago, MikeOH said:

HP-15C for the win!

(Still use mine daily)

Nah. No alphanumeric display on that one. Running strong in daily use since 1984.

HP-41CX. Helped me with two college degrees.

[dkkim73]

20 minutes ago, MikeOH said:

HP-15C for the win!

Now *that's* what I'm talking 'bout!

Wish I could find mine. A more elegant weapon from a more civilized age...

[Shadrach]

1 hour ago, 1980Mooney said:

No doubt the diameter of a 6.00X6 6 ply is 16.8-17.5" when pumped up to 42 psi and laying on the ground.  But at normal pressure and under load the tire will deflect and the effective diameter (and radius) will be less.  Both Michelin and Goodyear state that the "Static Loaded Radius (Inches) At Rated Load" is 6.9 inches. (effective 13.8 inch diameter)

All metal wing Mooneys roll on the same size tires regardless of 2,450 lb. MGW or 3,368 lb. MGW.  You probably don't inflate to 42 psi or roll with 1,750 lb on each main but reality is somewhere in between.

michelin_aircraft.pdf (jupitor.co.jp)

tire-specifications-6-2018.pdf (goodyearaviation.com)

this is getting pretty nerdy but I’ll bite…

1) Why are you using the static load radius to calculate the RPM of a spinning wheel?

2) Static load is very likely based on max rated load. The max rated load of each main tire exceeds my aircrafts empty weight. They are no where near the spec static load radius in use whether stationary or rolling down the runway.

[EricJ]

For the HP calculator nerds, my last actual HP calculator (grad school, iirc) is an HP-42S, which is an awesome calculator.   There is a free HP-42S emulator that runs on both cell phones and PCs, including Android, iOS, Windows, MacOS, and Linux (the guys that makes it must truly be an uber-geek to support everything like that).   It's excellent and indistinguishable from actual HP-42S on my phone.   I've used it for years, and it gives you HP-RPN calculator goodness at your fingertips on your phone and your PC.  Highly recommended.

https://thomasokken.com/free42/

Edit:  BTW, it has skins to make it look like an HP-15, HP-41, etc.    Your fave may be on there if you don't like the HP-42S layout.

[EricJ]

My personal HP calculator museum, from undergrad and grad school.   The LED displays or batteries on the old ones are kaput.

 

[MikeOH]

1 hour ago, Hank said:

Nah. No alphanumeric display on that one. Running strong in daily use since 1984.

HP-41CX. Helped me with two college degrees.

Ah, so you were one of those 'rich' college kids...the HP-15C was all I could afford!

 

[Andy95W]

2 hours ago, EricJ said:

 

Real nerds use HP calculators. 

Reverse Polish notation FTW! 

The first time I heard “Reverse Polish Notation” in 1984 with my HP-15C, I swore it had to be a joke.

Excellent device, I doubt I could use it anymore!

[LANCECASPER]

1 hour ago, Andy95W said:

The first time I heard “Reverse Polish Notation” in 1984 with my HP-15C, I swore it had to be a joke.

I thought that was a wrestling move . . . .  very similar to a Half-Brzezinski. 

[Andy95W]

5 minutes ago, MikeOH said:

Ah, so you were one of those 'rich' college kids...the HP-15C was all I could afford!

 

You were both rich kids compared to me… I was issued (forced to buy) my HP-15C my first year at West Point.

[Kelpro999]

I tap mine. Seems to make bar easier though mid stroke.

[0TreeLemur]

2 hours ago, EricJ said:

Reverse Polish notation FTW! 

My wife and I used to run a small web-based business selling HP scientific calculators to an elite global clientele.  Nerds with money who can't go without a replacement when they drop their calculator into the North Sea or some such mishap.   We gave it up as our sales declined due to effective emulators on cell phones and retirement of folks who grew up with them.   We were left with a significant inventory.  Sold it for enough to buy a 430W for our C!    I didn't sell all of them though...

 

Edited January 11, 2024 by 0TreeLemur
added photo

[N201MKTurbo]

25 minutes ago, 0TreeLemur said:

My wife and I used to run a small web-based business selling HP scientific calculators to an elite global clientele.  Nerds with money who can't go without a replacement when they drop their calculator into the North Sea or some such mishap.   We gave it up as our sales declined due to effective emulators on cell phones and retirement of folks who grew up with them.   We were left with a significant inventory.  Sold it for enough to buy a 430W for our C!    I didn't sell all of them though...

 

I'm a TI man, I never warmed up to the RPN thing. I can run one, but it just seems backwards.