seb146
Topic Author
Posts: 18239
Joined: Wed Dec 01, 1999 7:19 am

Airbus 319/320/321 Front Gear

Tue Oct 23, 2018 7:23 pm

It is probably just me, but every time I see one of the listed Airbus types, the front gear seems to be slanted forward and not more straight up and down. I think not all gear are straight but these types it seems more pronounced.

Am I crazy (don't answer that, I already know) or does this gear seem off? And, if the gear is off, why?
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Lpbri
Posts: 131
Joined: Tue Sep 27, 2016 7:18 pm

Re: Airbus 319/320/321 Front Gear

Tue Oct 23, 2018 11:05 pm

Looks like this plane is in a turn
 
Max Q
Posts: 6816
Joined: Wed May 09, 2001 12:40 pm

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 12:55 am

It’s not just you


The A 320 series do have a forward
slant in the nose gear



If you look at some pictures of
the DC10 and MD11 you’ll notice
they share this design feature


As a result in a tight turn on the ground the
outboard nose wheel tire is actually
lifted off the ground
The best contribution to safety is a competent Pilot.
 
seb146
Topic Author
Posts: 18239
Joined: Wed Dec 01, 1999 7:19 am

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 1:03 am

But why? For the same reason main gear on 767 and A330 are slanted when they are off the ground?
You bet I'm pumped!!! I just had a green tea!!!
 
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fr8mech
Posts: 7338
Joined: Mon Sep 26, 2005 9:00 am

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 1:23 am

seb146 wrote:
But why? For the same reason main gear on 767 and A330 are slanted when they are off the ground?


Main gear bogies are normally tilted so they can fit into the wheel well.

Why does a manufacturer choose to design a forward cant into their nose gear, and center gear, in the case of the DC-10/MD11? I've no idea. It does look sleeker.
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Unless it's expressly prohibited, it's allowed.
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stratclub
Posts: 439
Joined: Fri Jan 05, 2018 10:38 pm

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 2:31 am

Borrowed from automotive references:

Positive Caster
Increasing the amount of positive caster will increase steering effort and straight line tracking, as well as improve high speed stability and cornering effectiveness. Positive caster also increases tire lean when cornering (almost like having more negative camber) as the steering angle is increased.
https://en.wikipedia.org/wiki/Caster_angle

Why doesn't Boeing use positive caster on the nose gear? I have no clue.
 
seb146
Topic Author
Posts: 18239
Joined: Wed Dec 01, 1999 7:19 am

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 3:56 am

stratclub wrote:
Borrowed from automotive references:

Positive Caster
Increasing the amount of positive caster will increase steering effort and straight line tracking, as well as improve high speed stability and cornering effectiveness. Positive caster also increases tire lean when cornering (almost like having more negative camber) as the steering angle is increased.
https://en.wikipedia.org/wiki/Caster_angle

Why doesn't Boeing use positive caster on the nose gear? I have no clue.


Would it add more weight? They would probably have to engineer a whole new system.

The "positive caster" article explains so much. Thank you!
You bet I'm pumped!!! I just had a green tea!!!
 
User avatar
glen
Posts: 339
Joined: Thu Jun 30, 2005 4:43 pm

Re: Airbus 319/320/321 Front Gear

Wed Oct 24, 2018 4:46 pm

stratclub wrote:
Borrowed from automotive references:

Positive Caster
Increasing the amount of positive caster will increase steering effort and straight line tracking, as well as improve high speed stability and cornering effectiveness. Positive caster also increases tire lean when cornering (almost like having more negative camber) as the steering angle is increased.
https://en.wikipedia.org/wiki/Caster_angle

Why doesn't Boeing use positive caster on the nose gear? I have no clue.

You can have a similar effect like positive caster by placing the vertical axis of the nose strut ahead of the axis of the wheels. It's called trailing. That's how it's done on the larger Airbus models and by Boeing (and many others):
"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein
 
stratclub
Posts: 439
Joined: Fri Jan 05, 2018 10:38 pm

Re: Airbus 319/320/321 Front Gear

Thu Oct 25, 2018 3:49 pm

glen wrote:
stratclub wrote:
Borrowed from automotive references:

Positive Caster
Increasing the amount of positive caster will increase steering effort and straight line tracking, as well as improve high speed stability and cornering effectiveness. Positive caster also increases tire lean when cornering (almost like having more negative camber) as the steering angle is increased.
https://en.wikipedia.org/wiki/Caster_angle

Why doesn't Boeing use positive caster on the nose gear? I have no clue.

You can have a similar effect like positive caster by placing the vertical axis of the nose strut ahead of the axis of the wheels. It's called trailing. That's how it's done on the larger Airbus models and by Boeing (and many others):

Just like the "casters" (front wheels) on a shopping cart or tool box. Obviously Boeing does it that way because it's a simpler to design support structure for so perhaps there might be some weight savings over angling the gear to achieve positive caster like Airbus does.

Image
 
Max Q
Posts: 6816
Joined: Wed May 09, 2001 12:40 pm

Re: Airbus 319/320/321 Front Gear

Sat Oct 27, 2018 11:29 pm

If you’ve seen a picture of the outboard nose wheel Tyre lifting
off the ground in a tight turn on
the DC10/ MD11 and realize what a
tiny patch of rubber is still in contact with the ground to steer the aircraft this design seems dubious to say the least
The best contribution to safety is a competent Pilot.

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