Retractable gear questions

CMongoose said:
I tap the brakes on takeoff before retracting but I don't think it really makes a difference. a) I leave the gear down longer than most just in case of a low level engine failure and b) the gear transit time for a Cardinal is over 20 seconds. By the time they are in the wells, they wouldn't be spinning anyway.
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Hmm.. I think it is 12 seconds for my '76 177RG. I thought it was about half that for the '78, and no longer than 12 seconds for any of the earlier models. Which year RG do you have?

And yes, I tap the brakes as the gear are coming up, before they lock in the up position. I've never seen this on any checklist, and it's definitely not an absolutely have-to-do thing, but every CFI I've flown with has recommended doing it.
 
I always tap the brakes first in the Cardinal (1975). It's in MY checklist but I don't know if it's in the POH.

Rationale? I saw a video of how the gear retracts. They kind of "fall limp" and then the wheels are pulled up into wells perpendicular to direction of motion. I think the centrifugal force of spinning wheels that were approaching 65 MPH when freed from ground drag could have a negative effect. Could be an OWT.

 
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I always tap the breaks for good luck before taxiing away from the hangar.
 
I was taught to tap the brakes prior to retracting the gear (Debonair) but different people have different takes on it. If wheel rotation within the well is an issue, there would be a POH checklist item, otherwise, it doesn't really make any difference. I stopped doing it in the Arrow years ago.
 
This is what my Owners Manual says about it:

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And I don't always remember.

Our flight school got a grease streak on a 172 tire one time, cleary visible from the ramp. It generally stopped rotating before treetop level, which is generally about where my gear retraction is finished. There are, of course, no brakes on the nose wheel anyway, although there is a mechanism to straighten out the nose wheel during retraction.
 
Hank S said:
This is what my Owners Manual says about it:

View attachment 55418

And I don't always remember.

Our flight school got a grease streak on a 172 tire one time, cleary visible from the ramp. It generally stopped rotating before treetop level, which is generally about where my gear retraction is finished. There are, of course, no brakes on the nose wheel anyway, although there is a mechanism to straighten out the nose wheel during retraction.
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It also shows to reduce prop, and I know most of us keep full prop/full MP until cruise altitude.
 
Ravioli said:
I always tap the brakes first in the Cardinal (1975). It's in MY checklist but I don't know if it's in the POH.

Rationale? I saw a video of how the gear retracts. They kind of "fall limp" and then the wheels are pulled up into wells perpendicular to direction of motion. I think the centrifugal force of spinning wheels that were approaching 65 MPH when freed from ground drag could have a negative effect. Could be an OWT.

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Dash 2 needs some formation practice. I got sick just watching it.
 
azure said:
Hmm.. I think it is 12 seconds for my '76 177RG. I thought it was about half that for the '78, and no longer than 12 seconds for any of the earlier models. Which year RG do you have?

And yes, I tap the brakes as the gear are coming up, before they lock in the up position. I've never seen this on any checklist, and it's definitely not an absolutely have-to-do thing, but every CFI I've flown with has recommended doing it.
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I have the 76, same as you, and you're right it looks like 12. Oops!
 
rbridges said:
It also shows to reduce prop, and I know most of us keep full prop/full MP until cruise altitude.
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I usually pull back the prop at least a little bit in order to be nice to the neighbors.
 
Clark1961 said:
We do?
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Yes, we do. WOT/ 2700 from the runway to cruise. At Vy, too, as long as Oil Temp is alright, which is almost all the time now that I've resurrected my ailing doghouse that Vintage Mooneys have instead of baffling under the cowl . . . And yes, I watch CHT, too.

Neither was a problem climbing to 7500 msl at Vy a couple of weeks ago, in Alabama where the ambient temperature was in the mid-90s. It was a cool 68°F at 7500, instead of the Standard 32°F. Felt pretty good! Who needs air conditioning anyway? :p
 
Hank S said:
Yes, we do. WOT/ 2700 from the runway to cruise. At Vy, too, as long as Oil Temp is alright, which is almost all the time now that I've resurrected my ailing doghouse that Vintage Mooneys have instead of baffling under the cowl . . . And yes, I watch CHT, too.

Neither was a problem climbing to 7500 msl at Vy a couple of weeks ago, in Alabama where the ambient temperature was in the mid-90s. It was a cool 68°F at 7500, instead of the Standard 32°F. Felt pretty good! Who needs air conditioning anyway? :p
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That's what you do. No 'we' there.
 
Ravioli said:
I always tap the brakes first in the Cardinal (1975). It's in MY checklist but I don't know if it's in the POH.

Rationale? I saw a video of how the gear retracts. They kind of "fall limp" and then the wheels are pulled up into wells perpendicular to direction of motion. I think the centrifugal force of spinning wheels that were approaching 65 MPH when freed from ground drag could have a negative effect. Could be an OWT.
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The fall-limp thing happens when the airplane is on jacks in the shop, too, without the wheels spinning. As soon as the downlocks releaase, the gear falls much faster than the hydraulics can pump the oil, which puts tremendous vacuum into the "up" system. It takes the pump a few seconds to catch up, fill the vacuum with oil, and push the gear the rest of the way up.

The gear has a single pivot for each leg. It looks like there are two different things happening there, but it's one hinge axis. Simple system, really, though it has its weaknesses. One of the more serious is the fact that most airplanes don't get their rubber parts replaced every five years as per Cessna recommendations; some of them are 40 years old. If certain of those seals fail in flight with the gear up, it cannot be lowered and locked with either the electric pump or the hand pump. Gravity and/or airflow can't get those mains forward. One busted O-ring will do it. One.

The Cessna single retractables have a plastic liner in the wheel well. It warps and bulges in some airplanes. If the tire is spinning it can rub on that bulged liner and wear a hole in it. A hole lets water and dirt in against the aluminum airframe. Corrosion and extra weight and stuff.
 
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GRG55 said:
He said "most".

We already know you are an outlier. But thanks for the reminder. ;)
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I'm thinking the most part is the error but thanks for playing.
 
AggieMike88 said:
Q2 for our GA pilots who fly a retract gear airplane: similar question for you... are the wheels still turning once they reach th stowed position? Does your POH indicate this is they way it should be? Or do you take an action to reduce or stop the wheel spin as the gear travels to the stowed position?
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Best to read the POH.

The technique varies a bit depending on the airplane.

In light aircraft I will lightly apply brakes before retracting.

I don't touch the brakes in larger aircraft like my Beech 18, or something like the DC-3 or B-25.

The reason is the brakes on those airplanes are much more powerful and the weight of the wheels/momentum of spinning such that you can actually do damage by applying brakes to free spinning wheels. The B-25 is probably the most extreme example: the brakes are so effective and wheels so heavy that you can literally shear the valve stems off by applying brakes before retraction.
 
Wow....stops so fast it shears valve stems? :eek:
Fearless Tower said:
Best to read the POH.

The technique varies a bit depending on the airplane.

In light aircraft I will lightly apply brakes before retracting.

I don't touch the brakes in larger aircraft like my Beech 18, or something like the DC-3 or B-25.

The reason is the brakes on those airplanes are much more powerful and the weight of the wheels/momentum of spinning such that you can actually do damage by applying brakes to free spinning wheels. The B-25 is probably the most extreme example: the brakes are so effective and wheels so heavy that you can literally shear the valve stems off by applying brakes before retraction.
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Lycoming says keep the black knob firewalled in climb. Some engines call for an early reduction of the RPM (2 or 5 minutes).
Read the manual on your engine.
 
Hank S said:
Yes, we do. WOT/ 2700 from the runway to cruise. At Vy, too, as long as Oil Temp is alright
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I'm with you on the WOT and 2700 to cruise, but once I'm 1500agl or so I transition from Vy to a cruise climb of about 120kts and still maintain a 500fpm climb up to 7-8k msl depending on temps. More air through the engine for better cooling, and cover more ground in the climb.
 
The checklist on my 74 Cardinal RG says to tap the breaks when retracting the gear
 
Chip Sylverne said:
It would be interesting to have someone with a GoPro make a vid and see how long the wheels actualy spin on a small GA aircraft. My guess is it's not that long; not all that much rotating mass and some normal light friction from the brake pads probably have them stopped pretty quick.
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Here's a video of my Mooney taken from below the empennage. I don't tap my brakes on takeoff, and the mains have stopped rotating by the time I raise the gear.

 
Beautiful plane, Joe, and I love the climbout. But you wait an awful long time to retract the gear. Mine are usually stowed by treetop level. Then again, you have an extra 100+ hp to climb with! :eek: I put the wheels away to enhance my climb rate, and sooner is better; my home field does not have room to land again by 50' agl, so altitude is safety.
 
And the answer is: 42...


I don't see what the big deal is - as long as you put the gear DOWN before landing ....
 
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Hank S said:
Beautiful plane, Joe, and I love the climbout. But you wait an awful long time to retract the gear. Mine are usually stowed by treetop level. Then again, you have an extra 100+ hp to climb with! :eek: I put the wheels away to enhance my climb rate, and sooner is better; my home field does not have room to land again by 50' agl, so altitude is safety.
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It's because I departed from a 10,000' runway and keep the gear down while I still have usable runway ahead of me. At shorter fields I retract them much earlier.
 
rbridges said:
Can't say I feel anything different or noticed any rubbing in the wheel wells.
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On a rental Arrow that I used to fly often, the vibration of wheels was a good reminder. Can't feel anything on the Mooney. Seems like a result of who has done the last tire and tube replacement.
 
My gear is usually stowed with alacrity, but I've got to do it fast or the forces make it nearly impossible to swing the Johnson bar.
I always climb at 25 square. I started because that's what it says to do in the owners manual. At least one guy on Mooneyspace has claimed he burns less oil doing this. I believe it, mine burns very little, a quart every ten hours if that.
 
colojo said:
Here's a video of my Mooney taken from below the empennage. I don't tap my brakes on takeoff, and the mains have stopped rotating by the time I raise the gear.

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Was that at Centennial?
 
Another Mooney belly view. I pull the gear pretty quick, and the tires are still stopped by the time I do it.

 
It's in the POH to tap the breaks for RG Cessnas. Due to centrifugal force, the tire will expand somewhat and there is very little clearance for the mains to tuck up into the fuselage. When the mains drop, the wheels turn perpendicular to the relative wind prior to retracting fully. I would think the wheels would slow their rotation significantly at that point and the expansion would subside. But hey, why chance it?
 
The rumble you were hearing is more likely to have been the airflow over the gear doors as they close. Its turbulent and makes quite a racket.
The others have answered the brake question and I'll just add that on my Cessna straight leg I hit the brakes sometimes when I have passengers who might get nervous due to the gear legs shaking from the out of balance wheels. Doesn't take long for them to stop on their own but a little help doesn't hurt.

Frank
 
labbadabba said:
It's in the POH to tap the breaks for RG Cessnas. Due to centrifugal force, the tire will expand somewhat and there is very little clearance for the mains to tuck up into the fuselage
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LOL right... Sorry. The real reason for stopping rotation on any retractable is in case a tire blows on takeoff, so it doesn't damage the aircraft or get lodged in the wheel well, possibly preventing extension.
 
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What ever you do, don't use the parking brake. I saw an Airbus wheel that was flat spotted (the wheel, not the tire) because the FO set the parking brake in flight prior to landing.
 
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