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Thread: Steerable Nose Gear Vs. Castering Nose Gear?

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    Registered User K-Rigg's Avatar
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    Steerable Nose Gear Vs. Castering Nose Gear?

    I'm debating which one to go with.

    The steering nose gear is obvious superior in ground handling, and i have been studying the ch-601 nose gear, but there are a couple things i do not like about them. 1. The Nose Gear is directly connected to the rudder peddles, so if you bent the front gear on a landing, there is a possibility you will lose the ability to steer. 2. More complex (More weight)

    The castering nose wheel has a couple concerns for me also. I have read about tendencies of the nose gears to dig in on the RV and collapse the nose gear. Ground handling would be a concern, do the brakes wear out quickly, nose wheel shimmy becoming a problem?

    Any insight would be nice, I'm leaning to the steerable nose gear because all i fly are pipers and thats what I'm use too.
    Last edited by K-Rigg; June 23rd, 2009 at 12:40 AM.

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    Registered User K-Rigg's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    i dont want this to happen.


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    Super Moderator orion's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    I've flown Grummans for many years and have owned two. While the castering nose-wheel takes a bit of getting used to, once you do I wouldn't think you'd even notice the difference. In several instances I actually prefer it over conventional steering. The only time I ran into a bit of an issue was on a snow covered runway but even then it was manageable.

    At first glance you'd think the brakes might wear out sooner but if they do, I didn't notice too significant a difference in my airplanes, nor do I remember hearing anything from the club's maintenance folks.

    I don't know why the RV's nose gear would "dig in" but if you compare that gear with the nose strut on the Grummans, the latter seems to be quite beefy in comparison with the RV's.

    The only significant issue that has cropped up in most of these designs is the shimmy - in order to avoid the flutter motion is is very important that the geometry is properly configured and that some form of damper (mechanical or hydraulic) be utilized in order to reduce the chance of the tendency.

    In addition to the Grummans and RVs, other airplanes have decided on the castering nose-wheel also including the Glastar and the Glasair lines. And I'm sure others here may know of other examples.
    "To live is to learn; to learn is to live" (author unknown)

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    Super Moderator orion's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by K-Rigg View Post
    i dont want this to happen.
    But notice the efficient use of real-estate for parking.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User K-Rigg's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by orion View Post
    But notice the efficient use of real-estate for parking.
    what amazes me the most is the person taken the picture, if i was in that very spot watching that, i would be so shocked i couldn't press the button to take the picture.

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    Registered User K-Rigg's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?



    [video=youtube;NfaCGc16jQ0]http://www.youtube.com/watch?v=NfaCGc16jQ0]YouTube - RV6A flip at Croft Farm fly-in[/url][url="http://www.youtube.com/watch?v=NfaCGc16jQ0&feature=related[/video]


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    Registered User Mac790's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    I have a question for 1000 points, what is the name of the aircraft in the first movie? About first movie it looks like a positive rake, shouldn't it be a negative rake for free-swivel nose gear like it this Long Eze.


    Seb
    Last edited by Mac790; June 23rd, 2009 at 01:44 PM. Reason: link
    Amor Patriae Nostra Lex

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    Super Moderator orion's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Some years ago I remember an interesting discussion with the gentleman who headed up the structural branch of the Seattle FAA office at the time. When we got on the subject of landing gear, he indicated that based on work the FAA did about that time, they concluded that there was no homebuilt that could pass the Part 23 landing certification requirements.

    If you want to look at a real durable and stable swiveling gear, see if you can find a Grumman in your vicinity. Then simply compare the strut diameter of the Grumman and the RV - there's a substantial difference. True, the RV is solid and the Grumman is a tube, but for practical considerations, the inner material of the solid gear strut does little for you so the diameter comparison holds. Also look at the difference of how the gear is mounted.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User Lucrum's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by K-Rigg View Post
    I'm debating which one to go with.

    The steering nose gear is obvious superior in ground handling, and i have been studying the ch-601 nose gear, but there are a couple things i do not like about them. 1. The Nose Gear is directly connected to the rudder peddles, so if you bent the front gear on a landing, there is a possibility you will lose the ability to steer. 2. More complex (More weight)

    The castering nose wheel has a couple concerns for me also. I have read about tendencies of the nose gears to dig in on the RV and collapse the nose gear. Ground handling would be a concern, do the brakes wear out quickly, nose wheel shimmy becoming a problem?

    Any insight would be nice, I'm leaning to the steerable nose gear because all i fly are pipers and thats what I'm use too.
    You could have a separate tiller for the nose gear, so it wouldn't have to be connected to the rudder. In fact many jets and larger aircraft do that very thing.

    I've never flown an airplane designed with a castering nose gear.
    But I have flown two types of corporate jets on four occasions with failed nose wheel steering. While I think I prefer steerable gear, I'll admit I was surprised how well taxiing and ground handling went on those occasions. IMO if lower cost and or simplicity is a desire in your design. I wouldn't rule out a castering nose. Maybe it's worth renting a plane like that just to try it out before deciding.

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    Registered User K-Rigg's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by orion View Post
    Some years ago I remember an interesting discussion with the gentleman who headed up the structural branch of the Seattle FAA office at the time. When we got on the subject of landing gear, he indicated that based on work the FAA did about that time, they concluded that there was no homebuilt that could pass the Part 23 landing certification requirements.

    If you want to look at a real durable and stable swiveling gear, see if you can find a Grumman in your vicinity. Then simply compare the strut diameter of the Grumman and the RV - there's a substantial difference. True, the RV is solid and the Grumman is a tube, but for practical considerations, the inner material of the solid gear strut does little for you so the diameter comparison holds. Also look at the difference of how the gear is mounted.
    From my research on the Grumman front nose gear is that the front gear leg is connected to a torque tube. Does anyone have the specs on the Torque tube and the tube leg (tube diameter and wall thickness, material)?

  11. #11
    Super Moderator orion's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by K-Rigg View Post
    From my research on the Grumman front nose gear is that the front gear leg is connected to a torque tube. Does anyone have the specs on the Torque tube and the tube leg (tube diameter and wall thickness, material)?
    Correct - the nose gear mounting on the Grumman is separate from the engine mount. On the larger, four place aircraft that torque tube mounting also incorporates two pressurized shock absorbers. The latter is often also used on the two place airplanes that were upgraded to larger engines.

    I however can't find the spec. The largest distributor of Grumman parts is Fletcher Aviation in Texas (FletchAir - Parts for American, American General, Grumman-American, Gulfstream-American) - you might want to try there.
    "To live is to learn; to learn is to live" (author unknown)

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    Registered User flyoz's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    My 2 cents worth IMHO ...
    With castering nosewheel taking off in a crosswind may need some brake application to keep straight - so longer takeoff roll
    Taxing over bumpy ground can have some surprising results and i have seen an aircraft almost "slow ground loop " when one main wheel went into a slight hole before the pilot realised it would happen - but its an extreme case .
    Steerable nosewheels can have problems too
    Landing into a strong crosswind means you have rudder applied and when you touch down have to be sure to straighten up before you lower the nosewheel otherwise the aircraft will try to head off in the other direction .
    It brings into the equation differential braking
    Some steerable aircraft dont have differential braking which means that landing in a crosswind and putting down the nosewheel means its the only thing left to keep directional control - differential braking means you have another chance . Also if the nosewheel steering mechanism fails , you still have directional control .
    Differential brakes with steerable nosewheels put strong sideways thrust loads on the nosewheel if the pilot does not allow the brakes to follow the nosewheel like taxing etc
    Anyway its an interesting debate
    Flyoz

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    Registered User bmcj's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by Lucrum View Post
    You could have a separate tiller for the nose gear, so it wouldn't have to be connected to the rudder. In fact many jets and larger aircraft do that very thing.
    A well designed free swivel trailing nosewheel works fine and take very little time to adapt to.

    Bruce

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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    What about a simple locking design that unlocked for taxi needs? It certainly helped tame some taildraggers.

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    Registered User Dan Thomas's Avatar
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    Re: Steerable Nose Gear Vs. Castering Nose Gear?

    Quote Originally Posted by flyoz View Post
    My 2 cents worth IMHO ...
    With castering nosewheel taking off in a crosswind may need some brake application to keep straight - so longer takeoff roll
    Taxing over bumpy ground can have some surprising results and i have seen an aircraft almost "slow ground loop " when one main wheel went into a slight hole before the pilot realised it would happen - but its an extreme case .
    Steerable nosewheels can have problems too
    Landing into a strong crosswind means you have rudder applied and when you touch down have to be sure to straighten up before you lower the nosewheel otherwise the aircraft will try to head off in the other direction .
    It brings into the equation differential braking
    Some steerable aircraft dont have differential braking which means that landing in a crosswind and putting down the nosewheel means its the only thing left to keep directional control - differential braking means you have another chance . Also if the nosewheel steering mechanism fails , you still have directional control .
    Differential brakes with steerable nosewheels put strong sideways thrust loads on the nosewheel if the pilot does not allow the brakes to follow the nosewheel like taxing etc
    Anyway its an interesting debate
    Flyoz
    If you look at various spam cans, you'll see that airplane with differential braking often have a springy steering connection to the rudder pedals. Think Cessna. The Cessna nosegear has a cam affair that centers the gear when the nosewheel is off the ground so that it will track straight on touchdown even if the rudder is deflected. In fact, the nosegear is the centering device for the whole rudder control system. The gear is steerable but also has a castering tendency so that turns can be tightened beyond the steerable limits.

    Airplanes with a solid steering connection (Pipers) often had a brake lever; no differential.

    A lockable nosewheel would be impractial. Locking tailwheels are used on big taildraggers, but that's to limit groundlooping tendencies. Some of them unlock if the stick is shoved full forward, lock with stick back.

    Some of the Grummans had wheel fairings. The nosewheel had a long fairing that caused expensive and embarrassing problems if the airplane had been pushed back so that the nosewheel had castered all the way around and the fairing was sticking out into the prop arc. Much noise and debris on startup. An unanticipated design flaw, I'm sure.

    Nosewheel shimmy: On the Cessnas, the shimmy damper is next to useless. It's authority is via the scissors and steering yoke, both of which develop considerable slop and even with new bushings and shims to can be hard to get the play out. The holes in the aluminum parts wallow out a bit, increasing the slop, and those parts are awesomely expensive. Another factor is the nosgear's steering axis; it's a bit too vertical, decreasing the caster especially in a hard stop or if the strut is flat and the nose of the airplane dips. The best way to control shimmy, bar none, is to dynamically balance that nosewheel and tire asembly. Most of these expensive light aircraft tires are farther out of balance than cheap car tires and they'll shake and shimmy readily. With a castering nosewheel on a spring rod, the wheel's pivot angle needs to be tipped back from the vertical. Think bicycle steering angle. Applies to tailwheels, too, unless the manufacturer has reason to specify otherwise. It has to do with the arc of contact of the tire on the pavement; the firmest contact should be in the straight-ahead position, lifting slightly to either side. Tipping the top of the pivot forward ends up with the wheel bouncing from side-to-side, contact-to-contact.

    Dan

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