Nose Wheel Steering for Retracts

[Dan[_12_]]

I'm looking for a simple design for nose wheel steering for
retractable gear. Any ideas?

Dan, U.S. Air Force, retired

[Morgans[_7_]]

"Dan" > wrote in message
...
> I'm looking for a simple design for nose wheel steering for retractable
> gear. Any ideas?

Cables with the cables running over a pulley close to the pivot point on the
retract mechanics, with another spring and pulley keeping tension on any
slack that does develop.
--
Jim in NC

[bildan]

On Jun 24, 7:13*am, Dan > wrote:
> * *I'm looking for a simple design for nose wheel steering for
> retractable gear. Any ideas?
>
> Dan, U.S. Air Force, retired

"T-bar" above the gear strut retraction pivot point which swings back
into contact with roller bearings connected to the pedals as the nose
gear down-lock engages. Pedals would push roller bearings against T-
bar which would rotate gear strut to steer.

The roller motion would have to be reversed relative to the pedals so
pushing on the right pedal would make the nose gear steer right.

Strut would have to be spring loaded to keep it centered and steering
dampers would be needed.

[[email protected][_2_]]

On Jun 24, 7:13*am, Dan > wrote:
> * *I'm looking for a simple design for nose wheel steering for
> retractable gear. Any ideas?
>
> Dan, U.S. Air Force, retired

Morse cables?
============
Leon McAtee

[Dan[_12_]]

wrote:
> On Jun 24, 7:13 am, Dan > wrote:
>> I'm looking for a simple design for nose wheel steering for
>> retractable gear. Any ideas?
>>
>> Dan, U.S. Air Force, retired
>
> Morse cables?
> ============
> Leon McAtee

I came up with a fairly simple idea using hydraulics with brake
master cylinders to supply pressure. Problem is the wheel will either
still steer when retracted making for a big wheel well or any disconnect
system I can think of becomes complex beyond my pay grade.

I had considered cables but every sketch or model I can think of
tends to put a lot off stress on the cables or downloads tension when
retracted depending on which side of the pivot point the pulleys are.
This makes for some interesting spring configurations. If anyone has
solved that I'd like to hear what solution was derived.

The T bar idea Bildan suggests is interesting. I will have to do some
cogitation on that one.

Dan, U.S. Air Force, retired

[bildan]

On Jun 24, 10:57*am, Dan > wrote:
> wrote:
> > On Jun 24, 7:13 am, Dan > wrote:
> >> * *I'm looking for a simple design for nose wheel steering for
> >> retractable gear. Any ideas?
>
> >> Dan, U.S. Air Force, retired
>
> > Morse cables?
> > ============
> > Leon McAtee
>
> * *I came up with a fairly simple idea using hydraulics with brake
> master cylinders to supply pressure. Problem is the wheel will either
> still steer when retracted making for a big wheel well or any disconnect
> system I can think of becomes complex beyond my pay grade.
>
> * *I had considered cables but every sketch or model I can think of
> tends to put a lot off stress on the cables or downloads tension when
> retracted depending on which side of the pivot point the pulleys are.
> This makes for some interesting spring configurations. If anyone has
> solved that I'd like to hear what solution was derived.
>
> * *The T bar idea Bildan suggests is interesting. I will have to do some
> cogitation on that one.
>
> Dan, U.S. Air Force, retired

The system I described is used in some nose gear retract systems.
However, it is very direct steering with no 'give'. Some systems use
springs or elastomers to provide some 'softness' to the system.

One reason for softness is crosswind landings. If you touch down with
the controls crossed, (downwind rudder and upwind aileron) the nose
wheel steering will cause the airplane to dart to the downwind side of
the runway when the nosewheel touches unless the pilot remembers to
center the rudder. Adding some torsional "give" and some caster helps
with this.

An alternative to the T-Bar is a small "rudder post" connected to the
pedals with cables. The post is directly above and in line with the
nose strut when it's extended. The nose strut makes a rotary
connection with the post as the downlock engages. Sometimes this is a
slot-and-tang or other coupling method. The slot-&-tang will have a
bull nose on the tang and "V"lead-in on the slot so it engages
smoothly even if the pedals and nose strut aren't exactly aligned at
gear extension.

Landing gear design is a tricky business and a lot of things aren't
intuitive. One of my favorite stories is the last of the tailwheel
piston fighters. Enough 20 year old 2nd Lt's ground looped these
aircraft that the designers took notice and went back to their drawing
boards (Literally).

One solution was main gear struts that rotated outboard as they were
compressed. The idea was that when a swerve leading toward a
groundloop began, you wanted to "steer into the skid" as with a car.
The rotating main struts did this aromatically as the aircraft weight
shifted to the outboard main gear, compressing the strut, hopefully
giving the 2nd Louie another few seconds to save his butt.

[Morgans[_7_]]

"> I came up with a fairly simple idea using hydraulics with brake
> master cylinders to supply pressure. Problem is the wheel will either
> still steer when retracted making for a big wheel well or any disconnect
> system I can think of becomes complex beyond my pay grade.
>
> I had considered cables but every sketch or model I can think of tends
> to put a lot off stress on the cables or downloads tension when retracted
> depending on which side of the pivot point the pulleys are. This makes for
> some interesting spring configurations. If anyone has solved that I'd like
> to hear what solution was derived.

Tension the cables correctly when gear is in the down position, and have the
pulley at the pivot point arranged so some slack develops when gear is up.
Keep the cable under slight tension while up, so it does not jump a pulley
and so cables will not move the gear while up. That could be achieved by
putting a pulley around the cable in a long run attached to a light spring
going at a right angle to the cable run. That would keep things snug but
allow movement.
--
Jim in NC

[Rip[_3_]]

bildan wrote:
> On Jun 24, 7:13 am, Dan > wrote:
>> I'm looking for a simple design for nose wheel steering for
>> retractable gear. Any ideas?
>>
>> Dan, U.S. Air Force, retired
>
> "T-bar" above the gear strut retraction pivot point which swings back
> into contact with roller bearings connected to the pedals as the nose
> gear down-lock engages. Pedals would push roller bearings against T-
> bar which would rotate gear strut to steer.
>
> The roller motion would have to be reversed relative to the pedals so
> pushing on the right pedal would make the nose gear steer right.
>
> Strut would have to be spring loaded to keep it centered and steering
> dampers would be needed.

That's exactly how the gear on a Navion works, except that there is a
"V" slot to center the strut during retraction instead of spring
loading, and there are no dampers.

Rip

[Drew Dalgleish]

On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:

> I'm looking for a simple design for nose wheel steering for
>retractable gear. Any ideas?
>
>Dan, U.S. Air Force, retired

Have you considered just having a castering nosewheel? That's what I
have on my floats and it works pretty well steering with the brakes.

[Dan[_12_]]

Drew Dalgleish wrote:
> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
>
>> I'm looking for a simple design for nose wheel steering for
>> retractable gear. Any ideas?
>>
>> Dan, U.S. Air Force, retired
>
> Have you considered just having a castering nosewheel? That's what I
> have on my floats and it works pretty well steering with the brakes.

Yes, differential braking is probably the simplest method. I'm not
discarding it, just poking around at options.

Dan, U.S. Air Force, retired

[cavelamb[_2_]]

Dan wrote:
> Drew Dalgleish wrote:
>> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
>>
>>> I'm looking for a simple design for nose wheel steering for
>>> retractable gear. Any ideas?
>>>
>>> Dan, U.S. Air Force, retired
>>
>> Have you considered just having a castering nosewheel? That's what I
>> have on my floats and it works pretty well steering with the brakes.
>
> Yes, differential braking is probably the simplest method. I'm not
> discarding it, just poking around at options.
>
> Dan, U.S. Air Force, retired

Thisis an interesting pic.

http://www.infinityaerospace.com/Oriion_TS_gear.jpg
Not a lot of detail there, but the steerable strut seems to poke thru the top
and would meet with a steering link (tiller/thingie) there.

[bildan]

On Jun 24, 10:28*pm, cavelamb > wrote:
> Dan wrote:
> > Drew Dalgleish wrote:
> >> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
>
> >>> * I'm looking for a simple design for nose wheel steering for
> >>> retractable gear. Any ideas?
>
> >>> Dan, U.S. Air Force, retired
>
> >> Have you considered just having a castering nosewheel? That's what I
> >> have on my floats and it works pretty well steering with the brakes.
>
> > * Yes, differential braking is probably the simplest method. I'm not
> > discarding it, just poking around at options.
>
> > Dan, U.S. Air Force, retired
>
> Thisis an interesting pic.
>
> http://www.infinityaerospace.com/Oriion_TS_gear.jpg
> Not a lot of detail there, but the steerable strut seems to poke thru the top
> and would meet with a steering link (tiller/thingie) there.

I keep thinking about the "T-Bar" idea. If the rudder pedals had
control horns extending below the pedals hinge line with push rods
attached that extended forward to ball bearing rollers that pushed on
the right and left of the "T-Bar", that would provide the reverse
action to make the steering work right.

A push on the right pedal would pull back the push rod and roller
attached to it and the left pedal would push it's pushrod and roller
forward to turn the "T-Bar" to the right. When the gear was
retracted, the pushrods wouldn't have anything to push on.

If the nose gear strut was directly below the pedals, the pedals could
just have "spurs" with rollers on them.

[Brian Whatcott]

bildan wrote:
> On Jun 24, 10:28 pm, cavelamb > wrote:
>> Dan wrote:
>>> Drew Dalgleish wrote:
>>>> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
>>>>> I'm looking for a simple design for nose wheel steering for
>>>>> retractable gear. Any ideas?
>>>>> Dan, U.S. Air Force, retired
>>>> Have you considered just having a castering nosewheel? That's what I
>>>> have on my floats and it works pretty well steering with the brakes.
>>> Yes, differential braking is probably the simplest method. I'm not
>>> discarding it, just poking around at options.
>>> Dan, U.S. Air Force, retired
>> Thisis an interesting pic.
>>
>> http://www.infinityaerospace.com/Oriion_TS_gear.jpg
>> Not a lot of detail there, but the steerable strut seems to poke thru the top
>> and would meet with a steering link (tiller/thingie) there.
>
> I keep thinking about the "T-Bar" idea. If the rudder pedals had
> control horns extending below the pedals hinge line with push rods
> attached that extended forward to ball bearing rollers that pushed on
> the right and left of the "T-Bar", that would provide the reverse
> action to make the steering work right.
>
> A push on the right pedal would pull back the push rod and roller
> attached to it and the left pedal would push it's pushrod and roller
> forward to turn the "T-Bar" to the right. When the gear was
> retracted, the pushrods wouldn't have anything to push on.
>
> If the nose gear strut was directly below the pedals, the pedals could
> just have "spurs" with rollers on them.

Here's my fantasy design. Two tiny motorbike master cylinders, one on
each rudder pedal, and one slave cylinder on a horn each side of the
nose wheel.
Then the wheel could rotate and retract, and the hose pipes from brake
flexibles, would just flex. (Difficult to make this light enough, I
imagine.)

Brian W

[Dan[_12_]]

Brian Whatcott wrote:
> bildan wrote:
>> On Jun 24, 10:28 pm, cavelamb > wrote:
>>> Dan wrote:
>>>> Drew Dalgleish wrote:
>>>>> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
>>>>>> I'm looking for a simple design for nose wheel steering for
>>>>>> retractable gear. Any ideas?
>>>>>> Dan, U.S. Air Force, retired
>>>>> Have you considered just having a castering nosewheel? That's what I
>>>>> have on my floats and it works pretty well steering with the brakes.
>>>> Yes, differential braking is probably the simplest method. I'm not
>>>> discarding it, just poking around at options.
>>>> Dan, U.S. Air Force, retired
>>> Thisis an interesting pic.
>>>
>>> http://www.infinityaerospace.com/Oriion_TS_gear.jpg
>>> Not a lot of detail there, but the steerable strut seems to poke thru
>>> the top
>>> and would meet with a steering link (tiller/thingie) there.
>>
>> I keep thinking about the "T-Bar" idea. If the rudder pedals had
>> control horns extending below the pedals hinge line with push rods
>> attached that extended forward to ball bearing rollers that pushed on
>> the right and left of the "T-Bar", that would provide the reverse
>> action to make the steering work right.
>>
>> A push on the right pedal would pull back the push rod and roller
>> attached to it and the left pedal would push it's pushrod and roller
>> forward to turn the "T-Bar" to the right. When the gear was
>> retracted, the pushrods wouldn't have anything to push on.
>>
>> If the nose gear strut was directly below the pedals, the pedals could
>> just have "spurs" with rollers on them.
>
> Here's my fantasy design. Two tiny motorbike master cylinders, one on
> each rudder pedal, and one slave cylinder on a horn each side of the
> nose wheel.
> Then the wheel could rotate and retract, and the hose pipes from brake
> flexibles, would just flex. (Difficult to make this light enough, I
> imagine.)
>
> Brian W


I had considered that as I mentioned elsewhere in this thread. The
problems I can't get past is how to cut it out when retracted to reduce
rudder pedal effort and how to not interfere with differential braking.
I would think a castering nose wheel would be best with differential
braking, but one that's being steered could make for some interesting
effects.

Dan, U.S. Air Force, retired

[bildan]

On Jun 30, 5:52*am, Dan > wrote:
> Brian Whatcott wrote:
> > bildan wrote:
> >> On Jun 24, 10:28 pm, cavelamb > wrote:
> >>> Dan wrote:
> >>>> Drew Dalgleish wrote:
> >>>>> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
> >>>>>> * I'm looking for a simple design for nose wheel steering for
> >>>>>> retractable gear. Any ideas?
> >>>>>> Dan, U.S. Air Force, retired
> >>>>> Have you considered just having a castering nosewheel? That's what I
> >>>>> have on my floats and it works pretty well steering with the brakes..
> >>>> * Yes, differential braking is probably the simplest method. I'm not
> >>>> discarding it, just poking around at options.
> >>>> Dan, U.S. Air Force, retired
> >>> Thisis an interesting pic.
>
> >>>http://www.infinityaerospace.com/Oriion_TS_gear.jpg
> >>> Not a lot of detail there, but the steerable strut seems to poke thru
> >>> the top
> >>> and would meet with a steering link (tiller/thingie) there.
>
> >> I keep thinking about the "T-Bar" idea. *If the rudder pedals had
> >> control horns extending below the pedals hinge line with push rods
> >> attached that extended forward to ball bearing rollers that pushed on
> >> the right and left of the "T-Bar", that would provide the reverse
> >> action to make the steering work right.
>
> >> A push on the right pedal would pull back the push rod and roller
> >> attached to it and the left pedal would push it's pushrod and roller
> >> forward to turn the "T-Bar" to the right. *When the gear was
> >> retracted, the pushrods wouldn't have anything to push on.
>
> >> If the nose gear strut was directly below the pedals, the pedals could
> >> just have "spurs" with rollers on them.
>
> > Here's my fantasy design. Two tiny motorbike master cylinders, one on
> > each rudder pedal, and one slave cylinder on a horn each side of the
> > nose wheel.
> > *Then the wheel could rotate and retract, and the hose pipes from brake
> > flexibles, would just flex. (Difficult to make this light enough, I
> > imagine.)
>
> > Brian W
>
> * *I had considered that as I mentioned elsewhere in this thread. The
> problems I can't get past is how to cut it out when retracted to reduce
> rudder pedal effort and how to not interfere with differential braking.
> I would think a castering nose wheel would be best with differential
> braking, but one that's being steered could make for some interesting
> effects.
>
> Dan, U.S. Air Force, retired

[bildan]

On Jun 30, 5:52*am, Dan > wrote:
> Brian Whatcott wrote:
> > bildan wrote:
> >> On Jun 24, 10:28 pm, cavelamb > wrote:
> >>> Dan wrote:
> >>>> Drew Dalgleish wrote:
> >>>>> On Wed, 24 Jun 2009 08:13:28 -0500, Dan > wrote:
> >>>>>> * I'm looking for a simple design for nose wheel steering for
> >>>>>> retractable gear. Any ideas?
> >>>>>> Dan, U.S. Air Force, retired
> >>>>> Have you considered just having a castering nosewheel? That's what I
> >>>>> have on my floats and it works pretty well steering with the brakes..
> >>>> * Yes, differential braking is probably the simplest method. I'm not
> >>>> discarding it, just poking around at options.
> >>>> Dan, U.S. Air Force, retired
> >>> Thisis an interesting pic.
>
> >>>http://www.infinityaerospace.com/Oriion_TS_gear.jpg
> >>> Not a lot of detail there, but the steerable strut seems to poke thru
> >>> the top
> >>> and would meet with a steering link (tiller/thingie) there.
>
> >> I keep thinking about the "T-Bar" idea. *If the rudder pedals had
> >> control horns extending below the pedals hinge line with push rods
> >> attached that extended forward to ball bearing rollers that pushed on
> >> the right and left of the "T-Bar", that would provide the reverse
> >> action to make the steering work right.
>
> >> A push on the right pedal would pull back the push rod and roller
> >> attached to it and the left pedal would push it's pushrod and roller
> >> forward to turn the "T-Bar" to the right. *When the gear was
> >> retracted, the pushrods wouldn't have anything to push on.
>
> >> If the nose gear strut was directly below the pedals, the pedals could
> >> just have "spurs" with rollers on them.
>
> > Here's my fantasy design. Two tiny motorbike master cylinders, one on
> > each rudder pedal, and one slave cylinder on a horn each side of the
> > nose wheel.
> > *Then the wheel could rotate and retract, and the hose pipes from brake
> > flexibles, would just flex. (Difficult to make this light enough, I
> > imagine.)
>
> > Brian W
>
> * *I had considered that as I mentioned elsewhere in this thread. The
> problems I can't get past is how to cut it out when retracted to reduce
> rudder pedal effort and how to not interfere with differential braking.
> I would think a castering nose wheel would be best with differential
> braking, but one that's being steered could make for some interesting
> effects.
>
> Dan, U.S. Air Force, retired

I'm not sure I understand your concern. If the nose gear steering "T-
Bar" is above the nose strut pivot point, it will swing forward away
from the rollers as the nose gear retracts aft. There 'shouldn't' be
any residual extra effort from the pushrods since they wouldn't be
pushing against anything with the gear retracted.

I used to fly a Grumman Tiger with a castering nose wheel. It worked
OK but a long taxi in a crosswind would really heat up the downwind
brake - so much so that maneuvering in the runup area could be
problematic. Brake pads didn't last very long.

[[email protected][_2_]]

On Jun 30, 5:52*am, Dan > wrote:

> * *I had considered that as I mentioned elsewhere in this thread. The
> problems I can't get past is how to cut it out when retracted to reduce
> rudder pedal effort and how to not interfere with differential braking.

> Dan, U.S. Air Force, retired

A rotating valve. Similar to the one on a single handle kitchen
faucet, or as used to change the control arrangement on some back/
track hoes from Cat to JD?
==============
Leon McAtee

[cavelamb[_2_]]

Brian Whatcott wrote:
>
> Here's my fantasy design. Two tiny motorbike master cylinders, one on
> each rudder pedal, and one slave cylinder on a horn each side of the
> nose wheel.
> Then the wheel could rotate and retract, and the hose pipes from brake
> flexibles, would just flex. (Difficult to make this light enough, I
> imagine.)
>
> Brian W

I kinda suspect it would take a LOT more fluid flow than a brake master
could deliver - and a lot of pressure too.

[Brian Whatcott]

cavelamb wrote:
> Brian Whatcott wrote:
>>
>> Here's my fantasy design. Two tiny motorbike master cylinders, one on
>> each rudder pedal, and one slave cylinder on a horn each side of the
>> nose wheel.
>> Then the wheel could rotate and retract, and the hose pipes from
>> brake flexibles, would just flex. (Difficult to make this light
>> enough, I imagine.)
>>
>> Brian W
>
> I kinda suspect it would take a LOT more fluid flow than a brake master
> could deliver - and a lot of pressure too.


There's one FAA design requirement that I can remember: rudder pedals
shall withstand 150 lbs force each, without fail or stretch.

Brian W