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convair880mfan
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Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sat Aug 21, 2021 6:30 pm

In some photographs I have seen in books, it appear that the nose gear strut of the DC-10 is slightly tilted. Is that an optical illusion? And if it is tilted, what is the reason for that? Not being an engineer or aerodynamicist, I would think it would be better and safer if the strut met the runway, taxiway or apron at a 90 degree angle. Thanks to one and all for your responses.
 
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fr8mech
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sat Aug 21, 2021 8:58 pm

It is canted forward, as is just about every other Douglas aircraft I can think of.

I can’t recall why Douglas chose to do it that way.

Fun fact…the center gear on the MD11 is also canted.
 
r6russian
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sat Aug 21, 2021 9:45 pm

alot of nose gears have a positive caster by design to improve straight line handling and promote self centering. Its same as the positive caster built into the front suspension in your car, it forces the wheel to self center and track straight. If it had a negative caster, the wheel would try to go off center by itself, making you have to actively keep the car driving in a straight line, or just be completely undriveable (lilke flying a relaxed stability fighter without FBW)

another solution is to put the nose wheel axis behind the vertical axis of the nose strut, that way the nose gear strut pulls the wheels behind it, keeping them straight, like an F15 nose gear or the front wheels on a shopping cart

sometimes theyre used together, but its all for the same effect. straight line stability
 
Max Q
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sun Aug 22, 2021 6:44 am

Problem with the canted nose gear design is it completely lifts the outboard nose wheel off the ground in a tight turn while taxiing, now you’re steering with just one wheel, not so good, especially when you have a wet surface
 
StereoTechque
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sun Aug 22, 2021 1:18 pm

Max Q wrote:
Problem with the canted nose gear design is it completely lifts the outboard nose wheel off the ground in a tight turn while taxiing, now you’re steering with just one wheel, not so good, especially when you have a wet surface


Correct.
Tight turns mostly are done at lower speeds.
A320 Family can also be an example of Nose gear Castor of 9° Forward.
 
DH106
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sun Aug 22, 2021 4:58 pm

Stranger still was the Lockheed Constellation, which as well as having a forward angled nose gear, had considerable 'camber' on the nose wheel axles - meaning that the wheels were angled so that the bottoms of the tires where closer together than the tops. Perhaps this was to counteract to some extent the turning issues mentioned above?
 
StereoTechque
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sun Aug 22, 2021 5:04 pm

DH106 wrote:
Stranger still was the Lockheed Constellation, which as well as having a forward angled nose gear, had considerable 'camber' on the nose wheel axles - meaning that the wheels were angled so that the bottoms of the tires where closer together than the tops. Perhaps this was to counteract to some extent the turning issues mentioned above?


Classic example of a Positive camber.
Good for straight line stability and reducing steering effort.
 
battlegroup62
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 12:35 am

Max Q wrote:
Problem with the canted nose gear design is it completely lifts the outboard nose wheel off the ground in a tight turn while taxiing, now you’re steering with just one wheel, not so good, especially when you have a wet surface

I wouldn't say its a problem, it ensures slower speed turns. If such a tight turn is taken at a speed that one wheel can't maintain directional control perhaps the aircraft is being maneuvered too aggressively.
 
battlegroup62
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 12:37 am

StereoTechque wrote:
Classic example of a Positive camber.
Good for straight line stability and reducing steering effort.


And changing wheels without a jack. Not that anyone would ever use disobey an AMM.
 
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fr8mech
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 12:51 am

battlegroup62 wrote:

And changing wheels without a jack. Not that anyone would ever use disobey an AMM.


I may have witnessed that once or twice…quite possibly thrice on a DC-8.
 
Max Q
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 6:57 am

battlegroup62 wrote:
Max Q wrote:
Problem with the canted nose gear design is it completely lifts the outboard nose wheel off the ground in a tight turn while taxiing, now you’re steering with just one wheel, not so good, especially when you have a wet surface

I wouldn't say its a problem, it ensures slower speed turns. If such a tight turn is taken at a speed that one wheel can't maintain directional control perhaps the aircraft is being maneuvered too aggressively.



Maybe not


If you’re taxiing on a wet or icy surface in poor visibility you want all your tires touching the surface
 
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rjsampson
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 8:49 pm

battlegroup62 wrote:
And changing wheels without a jack. Not that anyone would ever use disobey an AMM.


Interesting! with all the weight on the wheels, how does that work exactly? Deflate the tire, replace with a deflated tire, re-inflate?
 
Dalmd88
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Mon Aug 23, 2021 9:25 pm

rjsampson wrote:
battlegroup62 wrote:
And changing wheels without a jack. Not that anyone would ever use disobey an AMM.


Interesting! with all the weight on the wheels, how does that work exactly? Deflate the tire, replace with a deflated tire, re-inflate?

Easy, turn on hydraulics, steer the nose to the good tire. Throw a chalk under it an turn off hydraulics. Pull and tag out the C/B for the electric hydraulics pump. The tire you want to change is now lifted off of the ground enough to change it. No, it is not an approved method if I recall.
 
LMP737
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Re: Does the DC-10 nose gear strut not meet the ground at a 90 degree angle?

Sat Oct 09, 2021 1:27 am

fr8mech wrote:
It is canted forward, as is just about every other Douglas aircraft I can think of.

I can’t recall why Douglas chose to do it that way.

Fun fact…the center gear on the MD11 is also canted.


I asked a Douglas engineer that long ago. His answer, it's inherently stable.

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