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Designers couldn't make up their mind, or what?

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StarJar

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Rudder hinges are always on the centerline rather than left or right surface/corner.
The center is the most awkward position to structurally install a hinge.
We all know p-factor creates an assymetrical use of the rudder.
My suggestion is mount them on new designs so the anti-p-factor-rudder deflection has the lions share of assymetrical surface deflection.
Is that too deep or novel for any of you. Or scary?
Tell me your observations or concerns please.
 
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gtae07

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People don't like asymmetry. And symmetrical structures are easier to analyze.

The Sonex has an asymmetrical rudder hinge, as does a certain large business jet. The E-2 has rudders on only 3 of its 4 vertical tails (the one without, the LH inboard one IIRC, is nicknamed the "executive tail").
 

BBerson

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My Grob has the hinge on the right side*. Elevator hinge on top.
I think the Lake Amphibian is similar.


*should have been the left side. The left turning prop requires full left pedal for takeoff, and in a right crosswind full left rudder isn't enough.
 

StarJar

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OK thanks guys. My life has just been vaidated, lol.
Honestly glad I'm not the first to try it.
But honestly, a centerline hinge would be one of the most awkward design jobs on my wood design.
 

TFF

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High end discus launch RC gliders use airfoiled vertical stab to get a compromise between high speed launch and low speed glide. It is not going to be a magic bullet though.
 

Jerry Lytle

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OK thanks guys. My life has just been vaidated, lol.
Honestly glad I'm not the first to try it.
But honestly, a centerline hinge would be one of the most awkward design jobs on my wood design.
I believe the latest Mini-Max drawing solve that problem for you. They are a free download.
 

Pops

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Ercoupe rudder hinges are on the outside of each rudder. They move to the inside just a few degrees. The elevator hinges are also on top.
 

StarJar

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Assertion presumes facts not in evidence.
It was an assertion I thought was correçt. But now I'm kind of embarrassed that side hinging is common knowledge, just about.

You learn something new every day! Almost.
I've found if I suspect my foot might be in my mouth, this forum will show me how my foot is in my mouth. Thank you.
 
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ScaleBirdsScott

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Another reason for center hinge might be some designs may not be able to presume the direction of bias the final engine install will need. Say a design that might take a O-200 or may take a VW, or something else: the kit/plans designer would either need the builder to know their engine up front and build th rudder either left or right handed, or, just make a symmetrical setup and let the owner trim it to suit.

At least that's what comes to mind.
 

BJC

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Rudder symmetry:

While physical symmetry may have great(er) visual impact, . . doesn't the root, basic goal of the rudder require aerodynamic symmetry?
The Glasair rudder is hinges on the right side. The difference in rudder area at full left deflection is less than at full right deflection by a small amount, about 12 square inches. I would not want to fly a 2200 pound airplane that had a rudder sized so that a loss of 12 square inches bacame critical.

Note that early glasairs, designed around the Lycoming O-235, needed larger rudders when builders installed O-360's. Note also that there were some instances of poor spin recovery in Glasairs which were related to the maximum rudder deflection having been set at a less than specified value.


BJC
 

BoKu

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It was an assertion I thought was correçt. But now I'm kind of embarrassed that side hinging is common knowledge, just about...
Here's what I try to do, though I don't always manage it in practice: When I find myself saying or writing the words "always" or "never," I stop, because I realize that I am about to be demonstrably and often embarrassingly wrong. It's a big world, and a bigger universe beyond. Pretty much everything has been tried, and a lot of it has been made to work at least a little. In a world where folks 3D print functional though functionally useless jet engines and drop smartphones into blenders just to hear the noise, a side-hinged rudder is a pretty small thing.

May be more on a glider; less on an engined aircraft.
Both of the most common 2-seat training gliders (ASK21 and G103), and many other gliders from the same manufacturers, have side-hinged rudders. There are slight asymmetric flight characteristics, but they are minor and you don't encounter them until you get close to the edge of the envelope. In the ASK21, as in several similarly-sized gliders, at very steep side-slip angles the rudder force gradient reverses, and the rudder stays against the stop until you re-center it with pressure on the appropriate pedal. It's no big deal unless you aren't expecting it, which is why most training regimens demonstrate the effect at least once. Anyhow, on the ASK21 the effect is more pronounced one way than the other.

Thanks, Bob K.
 

BJC

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... In a world where folks ... drop smartphones into blenders just to hear the noise, a side-hinged rudder is a pretty small thing.
Bob, if your fellow Californians are successful with this https://oag.ca.gov/system/files/initiatives/pdfs/16-0011 (Separate CA from US).pdf? we will be pleased welcome you to the USA.

In the ASK21, as in several similarly-sized gliders, at very steep side-slip angles the rudder force gradient reverses, and the rudder stays against the stop until you re-center it with pressure on the appropriate pedal. It's no big deal unless you aren't expecting it, which is why most training regimens demonstrate the effect at least once.
The prototype GlaStar also suffered from rudder lock. IIRC, the fix was to increase the chord of the rudder.


BJC
 
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