Today's Message Index:
----------------------
1. 05:51 AM - Aileron weight missing (James Grieco)
2. 05:53 AM - Aileron mass balance (James Grieco)
3. 07:09 AM - Re: Aileron mass balance (Ned Thomas)
4. 07:12 PM - Re: Aileron mass balance (Gary Vogt)
5. 10:57 PM - Re: Aileron mass balance (Gary L Vogt)
Message 1
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| Subject: | Aileron weight missing |
I think there is a misconception about the weight. Its specific job is as a mass
balance about the hinge line. If you draw a free body diagram of the aileron
with the weight and a chord wise cut of the aileron, the two masses balance around
the hinge bracket. When you apply a vertical gust, the inertia load on both
sides of the hinge is the same, and in the same direction, so the hinge bracket
gets wacked with combined load of the aileron mass + the counter weight
mass X the vertical gust factor. This means the aileron wouldn't rotate, but there
would be a large bending moment at the junction of the weight to tube welded
joint. With rust and continuous fatigue loading it could break. Since no aileron
rotation occurs, the rod would not hit the stop.
An estimate of the Max load and rod stress seen can be found by determining the
ultimate capability of the hinge bracket. Since I gather it did not fail, the
bending moment applied to the rod would be 1/2 the bracket ultimate load capability
X the length of the rod to the CG of the mass. The gust factor would
be 1/2 the bracket ultimate load divided by the weight of the counter weight up
to the weld.
Message 2
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| Subject: | Aileron mass balance |
I think there is a misconception about the weight. Its specific job is as a mass
balance about the hinge line. If you draw a free body diagram of the aileron
with the weight and a chord wise cut of the aileron, the two masses balance around
the hinge bracket. When you apply a vertical gust, the inertia load on both
sides of the hinge is the same, and in the same direction, so the hinge bracket
gets wacked with combined load of the aileron mass + the counter weight
mass X the vertical gust factor. This means the aileron wouldn't rotate, but there
would be a large bending moment at the junction of the weight to tube welded
joint. With rust and continuous fatigue loading it could break. Since no aileron
rotation occurs, the rod would not hit the stop.
An estimate of the Max load and rod stress seen can be found by determining the
ultimate capability of the hinge bracket. Since I gather it did not fail, the
bending moment applied to the rod would be 1/2 the bracket ultimate load capability
X the length of the rod to the CG of the mass. The gust factor would
be 1/2 the bracket ultimate load divided by the weight of the counter weight up
to the weld.
Message 3
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| Subject: | Re: Aileron mass balance |
Very good engineering analysis. Reminds me of the core classes back in college
days. It is consistent with what the pilot reported as well. Didn't the report
also say that BOTH counterweights departed the aircraft?
Ned
Sent from my iPad
On Jan 28, 2012, at 7:50 AM, James Grieco <jamesgrieco@yahoo.com> wrote:
>
> I think there is a misconception about the weight. Its specific job is as a mass
balance about the hinge line. If you draw a free body diagram of the aileron
with the weight and a chord wise cut of the aileron, the two masses balance
around the hinge bracket. When you apply a vertical gust, the inertia load on
both sides of the hinge is the same, and in the same direction, so the hinge
bracket gets wacked with combined load of the aileron mass + the counter weight
mass X the vertical gust factor. This means the aileron wouldn't rotate, but
there would be a large bending moment at the junction of the weight to tube welded
joint. With rust and continuous fatigue loading it could break. Since no
aileron rotation occurs, the rod would not hit the stop.
> An estimate of the Max load and rod stress seen can be found by determining the
ultimate capability of the hinge bracket. Since I gather it did not fail,
the bending moment applied to the rod would be 1/2 the bracket ultimate load capability
X the length of the rod to the CG of the mass. The gust factor would
be 1/2 the bracket ultimate load divided by the weight of the counter weight
up to the weld.
>
>
>
>
>
Message 4
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| Subject: | Re: Aileron mass balance |
OK, but, to get the weight into the slipstream far enough to get dragged on
, it has to move past the stop. -Otherwise, there would be a lot of torn
off weights.=0A=0A=0A________________________________=0A From: James Grieco
<jamesgrieco@yahoo.com>=0ATo: TeamGrumman <teamgrumman-list@matronics.com>
=0ASent: Saturday, January 28, 2012 5:50 AM=0ASubject: TeamGrumman-List: A
eco <jamesgrieco@yahoo.com>=0A=0AI think there is a misconception about the
weight. Its specific job is as a mass balance about the hinge line. If you
draw a free body diagram of the aileron with the weight and a chord wise c
ut of the aileron, the two masses balance around the hinge bracket. When yo
u apply a vertical gust, the inertia load on both sides of the hinge is the
same, and in the same direction, so the hinge bracket gets wacked with com
bined load of the aileron mass + the counter weight mass X the vertical gus
t factor. This means the aileron wouldn't rotate, but there would be a larg
e bending moment at the junction of the weight to tube welded joint. With r
ust and continuous fatigue loading it could break. Since no aileron rotatio
n occurs, the rod would not hit the stop. =0AAn estimate of the Max load an
d rod stress seen can be found by determining the ultimate capability of th
e hinge bracket. Since I gather it did not fail,- the bending moment appl
ied to the rod would be 1/2 the bracket ultimate load capability- X the l
ength of the rod to the CG of the mass. The gust factor would be 1/2 the br
acket ultimate load divided by the weight of the counter weight up to the w
====================
Message 5
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| Subject: | Re: Aileron mass balance |
I appreciate the lessons in strength of materials and statics, but it's more
than just a missing counterweight. I wish I'd taken pics. The end of the to
rque tube was sheared at the aileron bearing bracket. That degree of force h
as to be transferred to the aileron stop, if and only if, the bolt that does
the stopping is still there.
Gary
Sent from my iPad
On Jan 28, 2012, at 7:08 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
> OK, but, to get the weight into the slipstream far enough to get dragged o
n, it has to move past the stop. Otherwise, there would be a lot of torn of
f weights.
>
> From: James Grieco <jamesgrieco@yahoo.com>
> To: TeamGrumman <teamgrumman-list@matronics.com>
> Sent: Saturday, January 28, 2012 5:50 AM
> Subject: TeamGrumman-List: Aileron mass balance
>
m>
>
> I think there is a misconception about the weight. Its specific job is as a
mass balance about the hinge line. If you draw a free body diagram of the a
ileron with the weight and a chord wise cut of the aileron, the two masses b
alance around the hinge bracket. When you apply a vertical gust, the inertia
load on both sides of the hinge is the same, and in the same direction, so t
he hinge bracket gets wacked with combined load of the aileron mass + the co
unter weight mass X the vertical gust factor. This means the aileron wouldn'
t rotate, but there would be a large bending moment at the junction of the w
eight to tube welded joint. With rust and continuous fatigue loading it coul
d break. Since no aileron rotation occurs, the rod would not hit the stop.
> An estimate of the Max load and rod stress seen can be found by determinin
g the ultimate capability of the hinge bracket. Since I gather it did not fa
il, the bending moment applied to the rod would be 1/2 the bracket ultimate
load capability X the length of the rod to the CG of the mass. The gust fa
ctor would be 1/2 the bracket ultimate load divided by the weight of the cou
nter weight upamGrumman-List" target="_blank">http://www.matronics.com/Nav
igator?TeamGrumman-List<==================
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