77H
Topic Author
Posts: 1132
Joined: Mon Sep 19, 2016 11:27 pm

Lift System for 737 Landing Gear

Thu Jun 14, 2018 9:51 am

I was taking a look at pictures of the MAX and I remembered reading in related threads about the type that landing gear height limited engine size and rotation angles on take off especially for the MAX9 and the MadMAX.

My understanding is that the MAX10 will have a different style of gear that will help ground clearance and rotation angle that hasn’t been publized yet by Boeing.

Would it be possible to apply lifts (hydraulic or electric) to the gear such that the gear could be raised when down to allow for higher ground clearance, (possibly larger engines?) then lowered when retracted to fit in the wheel wells.

I imagine it would increase weights slightly but I imagine the gear to be used on MAX10 will be heavier than the MAX7-9.

I’d imagine this to be similar to the folding wingtips to be employed on the 777X.

How viable would this option for the MAX or feature aircraft ?

77H
 
travelhound
Posts: 1737
Joined: Fri May 23, 2008 9:13 pm

Re: Lift System for 737 Landing Gear

Thu Jun 14, 2018 10:02 am

The issue of raising the height of the landing gear revolves around the increased loads associated with the main strut which acts like a lever arm. You increase the length, you increase the weight and you increase the lever arm. If we consider aircraft are generally highly optimised small changes can have very substantial effects on supporting aircraft structures.
 
stratclub
Posts: 469
Joined: Fri Jan 05, 2018 10:38 pm

Re: Lift System for 737 Landing Gear

Thu Jun 14, 2018 6:03 pm

The -10 MAX landing gear function is explained some in this article: https://en.wikipedia.org/wiki/Boeing_737_MAX#737_MAX_10

Found these that seem to explain the concept of levering and telescoping the -10 max landing gear. It does look like the strut telescopes shorter and possibly moves slightly forward during retraction.

Boeing shows some videos at PAS:

https://twitter.com/thatjohn/status/877101578888589313
https://twitter.com/jonostrower/status/ ... 9319045121

The solution looks to be a lot more refined than using additional hydraulics. From what I could see, it is done by changing the geometry of some of the landing gear components.

Now if they could lower the location of the flight interphone jack it would be great. Even the -8MAX is taller than NextGen. When you unplug the interphone ground cord when you launch (for flight) a -8 MAX, I'm about 5 foot 11 and had to stand on my tip toes and could barely reach the top latch to secure external power/interphone panel door.
 
jetmatt777
Posts: 3590
Joined: Sun Jun 26, 2005 2:16 am

Re: Lift System for 737 Landing Gear

Fri Jun 15, 2018 2:17 am

stratclub wrote:
The -10 MAX landing gear function is explained some in this article: https://en.wikipedia.org/wiki/Boeing_737_MAX#737_MAX_10

Found these that seem to explain the concept of levering and telescoping the -10 max landing gear. It does look like the strut telescopes shorter and possibly moves slightly forward during retraction.

Boeing shows some videos at PAS:

https://twitter.com/thatjohn/status/877101578888589313
https://twitter.com/jonostrower/status/ ... 9319045121

The solution looks to be a lot more refined than using additional hydraulics. From what I could see, it is done by changing the geometry of some of the landing gear components.

Now if they could lower the location of the flight interphone jack it would be great. Even the -8MAX is taller than NextGen. When you unplug the interphone ground cord when you launch (for flight) a -8 MAX, I'm about 5 foot 11 and had to stand on my tip toes and could barely reach the top latch to secure external power/interphone panel door.


They should just put an auxiliary jack on the nose gear somewhere. That way they can keep commonality to an extent. But I don’t think they’ll do that.
Lighten up while you still can, don't even try to understand, just find a place to make your stand and take it easy
 
stratclub
Posts: 469
Joined: Fri Jan 05, 2018 10:38 pm

Re: Lift System for 737 Landing Gear

Fri Jun 15, 2018 5:41 am

jetmatt777 wrote:
stratclub wrote:
The -10 MAX landing gear function is explained some in this article: https://en.wikipedia.org/wiki/Boeing_737_MAX#737_MAX_10

Found these that seem to explain the concept of levering and telescoping the -10 max landing gear. It does look like the strut telescopes shorter and possibly moves slightly forward during retraction.

Boeing shows some videos at PAS:

https://twitter.com/thatjohn/status/877101578888589313
https://twitter.com/jonostrower/status/ ... 9319045121

The solution looks to be a lot more refined than using additional hydraulics. From what I could see, it is done by changing the geometry of some of the landing gear components.

Now if they could lower the location of the flight interphone jack it would be great. Even the -8MAX is taller than NextGen. When you unplug the interphone ground cord when you launch (for flight) a -8 MAX, I'm about 5 foot 11 and had to stand on my tip toes and could barely reach the top latch to secure external power/interphone panel door.


They should just put an auxiliary jack on the nose gear somewhere. That way they can keep commonality to an extent. But I don’t think they’ll do that.

That would do the trick, me thinks. Communality for parts that are rarely or never replaced isn't really an issue. Check out the solution that Boeing came up with for the -10 MAX being longer. Looks like a really clever bit of engineering. Impressive stuff, really.
 
Max Q
Posts: 6823
Joined: Wed May 09, 2001 12:40 pm

Re: Lift System for 737 Landing Gear

Fri Jun 15, 2018 9:07 am

Makes you wonder why Boeing didn’t develop this earlier

The -800 / 900 and 900 ER could all have benefited from a taller main landing gear, the lower take off and landing speeds and improved runway performance that would have provided


Not to mention a better looking aircraft on the ground and less tailstrikes.


This will be a side benefit on the -10, aesthetically a tall landing gear always improves an aircraft


And why the 787 with its short gear looks stumpy on the ground
The best contribution to safety is a competent Pilot.
 
stratclub
Posts: 469
Joined: Fri Jan 05, 2018 10:38 pm

Re: Lift System for 737 Landing Gear

Sat Jun 16, 2018 9:51 am

Max Q wrote:
Makes you wonder why Boeing didn’t develop this earlier

The -800 / 900 and 900 ER could all have benefited from a taller main landing gear, the lower take off and landing speeds and improved runway performance that would have provided


Not to mention a better looking aircraft on the ground and less tailstrikes.


This will be a side benefit on the -10, aesthetically a tall landing gear always improves an aircraft


And why the 787 with its short gear looks stumpy on the ground

Develop what exactly? Add addition complexity to the landing gear that is not needed? The next Gens and earlier meet all of their as designed performance requirements as proven through FAA validation testing. Other than adding addition weight, how are tall gear a benefit to an aircraft that performs as designed? Aesthetics? Not really a consideration in aircraft design. As it is, tail strikes are extremely rare.
 
User avatar
Erau82
Posts: 9
Joined: Mon Feb 20, 2017 5:10 pm

Re: Lift System for 737 Landing Gear

Sat Jun 16, 2018 11:23 pm

With only some scant details, it seems that the MLG will incorporate something similar to what the A340 MLG has which retracts the shock strut during the retraction sequence to allow the MLG to fit in the existing wheel well. If designed right, it would have little negative impact to dispatch reliability as it is a fully mechanical system. It will increase the overhaul costs by only a few manhours and add a few new bushings to be replaced. Not a big deal in my opinion.
 
User avatar
Starlionblue
Posts: 18709
Joined: Fri Feb 27, 2004 9:54 pm

Re: Lift System for 737 Landing Gear

Sun Jun 17, 2018 3:14 pm

Erau82 wrote:
With only some scant details, it seems that the MLG will incorporate something similar to what the A340 MLG has which retracts the shock strut during the retraction sequence to allow the MLG to fit in the existing wheel well. If designed right, it would have little negative impact to dispatch reliability as it is a fully mechanical system. It will increase the overhaul costs by only a few manhours and add a few new bushings to be replaced. Not a big deal in my opinion.


As with the 340, so also the 330.

It's called the "shortening mechanism", but for no good reason if it malfunctions the message is "lengthening fault".
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vc10
Posts: 1412
Joined: Thu Nov 15, 2001 4:13 am

Re: Lift System for 737 Landing Gear

Mon Jun 18, 2018 5:06 pm

Now I wonder where Airbus got that idea for their A340/330 from. Could i suggest. from Concorde which had shortening devices on both main Landing gears

Who is online

Users browsing this forum: 744lover, David L, United857 and 19 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos