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Are all three gear really down?


Mooneymite

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There is a really, really simple solution to these three pages of discussion.  Fix the gear down … and don't bring up the "D"; it was not designed as a fixed gear airplane. 

Yes, you might lose 10 knots (at worst), but you will also lose a lot of weight, a lot of complexity and a lot of maintenance.  And, with all the weight that is saved, you might be able to carry all the insurance and maintenance money you saved on your next vacation.  :D … just sayin'.

PS. And no Mooney owner has ever complained about the non-edible donuts.

Edited by Blue on Top
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On 1/24/2020 at 7:48 PM, Hank said:

Most of the gear up incidents are pilot failures, not equipment failures. Will watch these videos later.

Maybe linking the gear down switch to the COMS PTT button? (sorry if you land gear up in a calm airfield with no RT you just deserve it...)

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On 1/22/2020 at 8:31 PM, steingar said:

It's funny.  I always thought the one green light was overkill when I have the giant bar sticking out of my panel.  If the bar is where it's supposed to be and something's wrong, I think I'd rather not know.  My knowledge won't change the outcome, and at least without it  I suffer a little less dread.

I agree, what are you supposed to do with "gear up/down" state for practical flying/landing?

The only things I can think of are briefing pax, alerting fire services, long runway and making sure you have the right amount of fuel for a gear extended cruise or gear up landing...

I recently flew a rented Cardinal C177RG where gear failed to retract/extend, it was an electrical issue with gear pump & indication but all was ok on the hydraulics, the type had two mirrors that visually show the gear but it was fairly obvious they are fully extended from pressure in the manual gear pump handle and from fuel burn over a long distance as I was doing 95kts indicated at 10gph LOP (so visually checking like a maniac that flaps were not extended, door is open or some parachute is hanging behind :blink:), after my first landing I twisted the left mirror to show the font gear as I could see the left gear from the window under my shoulder, but what I am supposed to do with that "mirror indication", no idea?

If the device helps with avoiding distraction or spotting that you failed to operate the gear then super, if it causes more distraction to your flying, well probably better not to know, especially if it gives false signals, AFAIK, the success of landing with gear up is the same as any other landing: your speed at 50ft that you control and the stopping distance (you don't control), the rest of physics and flying skills are less relevant to some extent...

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On planes like Bo and C177, with a separate actuator for each wheel, a visual confirmation of each is important. A 2-wheel landing requires some skill to not go pear-shaped, and foreknowledge can make a difference.

Our gear all move together, except in the rare case a rod is physically broken. Besides, we have that nice thump below our seats as the mechanism travels over-center and locks. No thump, no speed control in the pattern / on approach, the gear isn't down. Check the green light, it's just a confirmation; check the floor indicator, mine is painted on a connecting rod and can't be wrong, I look and point at it on every final approach after checking the green light on downwind and base.

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9 hours ago, Hank said:

A 2-wheel landing requires some skill to not go pear-shaped, and foreknowledge can make a difference.

Of course it is better to know but how much of that will be different than what you already do on nice normal landing?

My point it is probably not the right time to try a new technique (other than what you know already: aiming for slow touchdown, ailerons cancels the drift and rudder to stay on the line, ok you know which one but you may skid the other way around as well), the rest will just happen fast while you are watching 

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2 hours ago, Ibra said:

Of course it is better to know but how much of that will be different than what you already do on nice normal landing?

My point it is probably not the right time to try a new technique (other than what you know already: aiming for slow touchdown, ailerons cancels the drift and rudder to stay on the line, ok you know which one but you may skid the other way around as well), the rest will just happen fast while you are watching 

Touch down gently, wheel down, no-wheel wing up, hold the nose off as long as possible, use lots of rudder when the no-wheel wing comes down . . . Less of an issue if it's the nose wheel that's missing. 

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Yes, better touch on whatever remaining main wheels you have than nothing preferably on a wide hard tarmac (I don't think raising the remaining one to be a sensible idea? ), unlike other types, not many (alive) Mooney drivers would dare touching on a front wheel first

Yoke, all the way back, maybe no ailerons and full rudder to pick no wheel wing for skilled guys
Flaps, all way down for low energy touch as in a normal landing (or I am missing something here?)
Power, idle on long runway one can argue about using some power to get directional/vertical control but I don't want to play with that under stress on one wheel
 

Edited by Ibra
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On 1/22/2020 at 10:40 AM, mooniac15u said:

AirMods bought my plane from the insurance company and flew it back to NJ without repairing the broken retraction tube.  If the over-center lock is in place then the gear isn't going anywhere.  I think they safety wired it in place.  They could probably give you the details if you contact them.

I wonder what their CHT's were like on that flight.

 

-Robert

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2 hours ago, Ibra said:

Yes, better touch on whatever remaining main wheels you have than nothing preferably on a wide hard tarmac (I don't think raising the remaining one to be a sensible idea? ), unlike other types, not many (alive) Mooney drivers would dare touching on a front wheel first

Yoke, all the way back, maybe no ailerons and full rudder to pick no wheel wing for skilled guys
Flaps, all way down for low energy touch as in a normal landing (or I am missing something here?)
Power, idle on long runway one can argue about using some power to get directional/vertical control but I don't want to play with that under stress on one wheel
 

Raising the remaining two gear and landing on the belly is the safest option.  People land gear-up all the time with no injuries and minimal damage to the aircraft.  Trying to land on one main gear and the nose gear puts you in an unknown situation with unpredictable results.  I used full flaps, shut off the engine, and held it off the runway as long as possible to bleed off speed.  It skidded about 300ft right down the center of the runway.  In the debrief the FAA inspectors agreed that the belly landing on the runway was the right choice.

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1 hour ago, mooniac15u said:

It skidded about 300ft right down the center of the runway.  In the debrief the FAA inspectors agreed that the belly landing on the runway was the right choice.

Thanks for sharing, 300ft to stop from 50kts is still like taking 5G for 10s, survivable but I don't think you do much flying there, I re-checked C177 POH, if main gears fail to fully extend/retract after pumping by hand, you put Gear UP and hope they swing inside with belly landing 

Yes, landing on remaining wheels may give more stopping distance but could end up really badly if you go off runway to one side or nose ditching in the soft (unless you can maintain yoke/rudder coordination at slow speeds while taking 7G)

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19 minutes ago, Ibra said:

Thanks for sharing, 300ft to stop from 50kts is still like taking 5G for 10s, survivable but I don't think you do much flying there, I re-checked C177 POH, if main gears fail to fully extend/retract after pumping by hand, you put Gear UP and hope they swing inside with belly landing 

Yes, landing on remaining wheels may give more stopping distance but could end up really badly if you go off runway to one side or nose ditching in the soft (unless you can maintain yoke/rudder coordination at slow speeds while taking 7G)

I think your math is off.  Decelerating from 50 knots over 300 ft is nowhere close to 5 Gs.

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26 minutes ago, mooniac15u said:

I think your math is off.  Decelerating from 50 knots over 300 ft is nowhere close to 5 Gs.

Sorry, I think formula for constant G is along Acceleration = 2*Speed*Speed/Distance, 1.25G if I do proper maths with proper metric/feet units :rolleyes: 

Edited by Ibra
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20 minutes ago, Ibra said:

Sorry, I think formula for constant G is along Acceleration = 2*Speed*Speed/Distance, 1.25G if I do proper maths with proper metric/feet units :rolleyes: 

You can also think of the landing gear as a vertical bumper. They can absorb a lot of force if you touch down hard. Otherwise a lot of vertical force could be transmitted through your spine. Of course you could try to touch down as soft as possible.

-Robert

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Overall Gs an aircraft would take is solely determined by speed and stop distance profiles, for vertical speeds stopping distance: simply 3ft, for forward speeds: ground run but I agree how that get transmitted to what is inside aircraft, say my head+spin, is a complex function of flex/rigid parts that take the hit first (e.g. prop, gear, engine, mounts, cushion...) and other parts that restraint you from amplifying that (e.g. 3/5 points harnesses...)

On forward speeds, my guess is breaking action on aircraft is different than car deceleration as the breaking profile is not flat and tend to peak at the end where speeds are slow (wing generates lift: less ground friction action at high speeds), so in theory an aircraft should average less Gs than those constant deceleration formula but no idea how much this is in practice? for vertical speeds, the only acceptable value for a wing generating lift is zero (flyers of BRS/CAPS are exempt from this)

Being able to jettison a heavy Lyco engine after touchdown on gear-up or off-field landing would be neat but I need to be dead sure I am not hitting anything in the front, including the engine I just dropped...

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On 1/27/2020 at 7:46 PM, PT20J said:

...add a parachute. :)

@carusoam  I will say that this would be closer in weight, but the additional weight for a parachute is the parachute plus the added structure plus the added bump on the outside for the parachute risers.  Keep trying … maybe eventually.  Seriously, how much useful load are you willing to compromise?

This sounds like a new thread to me :)

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Vertical Gs on a normal landing are very low (<<1G).  Landing gear is designed for 3G maximum before failure.  I believe that 3G is in the range of 10+ fps (600 fpm); similar to a carrier landing.  That's why carrier aircraft landing gear (and fuselages) are VERY beefy.  It is also why you'll see the gear move up and down a lot (so that load is not transmitted to the wing/aircraft).

As for longitudinal deceleration, I have seen higher than 0.3G (rubber to concrete friction can only go so high … even with anti-skid brakes).  If your brakes can hold your airplane stationary with full power ... 

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I like to be mis-credited...

At least Ron picked a knowledgable guy like Skip, to give me credit for his work... :)

 

If needed... land gear up. The Mooney was designed to handle it.  Done properly, the forces are evenly Distributed... some things will be ground off sheet metal and antennas... flaps get a few grinding marks as well....

If you get lucky... the prop stops near horizontal and doesn’t touch anything...

The cool thing... you are focused on saving your butt... not the insurance company’s prop...

Best regards,

-a-

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