Today's Message Index:
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1. 01:18 PM - Grumman Airfoil (Gary Vogt)
2. 01:59 PM - Re: Grumman Airfoil (Bob Steward)
3. 02:03 PM - Re: Grumman Airfoil (Bob Steward)
4. 03:32 PM - Re: Grumman Airfoil (Ronald Millman CPA)
5. 08:50 PM - Re: Grumman Airfoil (Gary Vogt)
6. 10:14 PM - Matronics Web Services Restored! (Matt Dralle)
Message 1
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Attach 1: -Grumman airfoil over layed on 64-415 at presumed zero line.=0A
Attach 2: -Grumman airfoil over layed on 64-415 at best fit.=0AAttach 3:
-Grumman airfoil over layed on 63-415 at presumed zero line. -(a thinne
r airfoil)=0A=0ABottom line is=0A1) The airfoil is slightly thinner than wh
at a computed 64-415 would be.=0A2) The forward flat portion of the wing is
the reference angle.
Message 2
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| Subject: | Re: Grumman Airfoil |
>Attach 1: Grumman airfoil over layed on 64-415 at presumed zero line.
>Attach 2: Grumman airfoil over layed on 64-415 at best fit.
>Attach 3: Grumman airfoil over layed on 63-415 at presumed zero
>line. (a thinner airfoil)
>
>Bottom line is
>1) The airfoil is slightly thinner than what a computed 64-415 would be.
>2) The forward flat portion of the wing is the reference angle.
The filled in trailing edge cusp on the Grumman airfoil vs. the NACA
ones is common, to reduce the loading on the controls. Basically a straight
>No virus found in this message.
>Checked by AVG - <http://www.avg.com>www.avg.com
Message 3
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| Subject: | Re: Grumman Airfoil |
>Attach 1: Grumman airfoil over layed on 64-415 at presumed zero line.
>Attach 2: Grumman airfoil over layed on 64-415 at best fit.
>Attach 3: Grumman airfoil over layed on 63-415 at presumed zero
>line. (a thinner airfoil)
>
>Bottom line is
>1) The airfoil is slightly thinner than what a computed 64-415 would be.
>2) The forward flat portion of the wing is the reference angle.
The filled in trailing edge cusp on the Grumman airfoil vs. the NACA
ones is common, to reduce the loading on the controls. Basically a
straight line is drawn from the pivot point of the aileron (or flap)
back to the trailing edge and the cusp is removed. You'll see this
on nearly every production aircraft.
Looks like they might have altered the point of max thickness to
accommodate the spar tube, so that its center is near the 25% MAC
point, where torque is usually summed for calculations on the torsion
box for the built up spar designs.
Thanks for the excellent plots Gary.
--Bob Steward
Message 4
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Thanks for keeping us up to date.Ron Millman N81218 1977 AA5B
Ronald D. Millman=2C C.P.A.
"The greatest good you can do for another
is not just to share your riches
but to reveal to him his own"
Benjamin Disraeli.
Hey..........=2C that's what a CPA does!
> Date: Wed=2C 7 Dec 2011 16:01:24 -0600
> To: teamgrumman-list@matronics.com
> From: n76lima@mindspring.com
> Subject: Re: TeamGrumman-List: Grumman Airfoil
>
om>
>
>
> >Attach 1: Grumman airfoil over layed on 64-415 at presumed zero line.
> >Attach 2: Grumman airfoil over layed on 64-415 at best fit.
> >Attach 3: Grumman airfoil over layed on 63-415 at presumed zero
> >line. (a thinner airfoil)
> >
> >Bottom line is
> >1) The airfoil is slightly thinner than what a computed 64-415 would be.
> >2) The forward flat portion of the wing is the reference angle.
>
> The filled in trailing edge cusp on the Grumman airfoil vs. the NACA
> ones is common=2C to reduce the loading on the controls. Basically a
> straight line is drawn from the pivot point of the aileron (or flap)
> back to the trailing edge and the cusp is removed. You'll see this
> on nearly every production aircraft.
>
> Looks like they might have altered the point of max thickness to
> accommodate the spar tube=2C so that its center is near the 25% MAC
> point=2C where torque is usually summed for calculations on the torsion
> box for the built up spar designs.
>
> Thanks for the excellent plots Gary.
>
> --Bob Steward
>
>
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>
>
>
Message 5
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| Subject: | Re: Grumman Airfoil |
Sometimes I think I take for granted everyone thinks the way I write. =C2
-It would sure be easier if you all did.=0A=0A1) Regarding the cusp on th
e 64-415 airfoil. =C2-I can come pretty close to approximating that if I
deflect the flap 1/4 to 1/2 inch. =C2-Not a big player in this discussion
.=0A2) The modified 64-415 airfoil, to make it thinner, is to get a better
fit to the Grumman airfoil.=0A=C2- =C2- =C2-=A2 The 15, in -415
, means the thickness of the airfoil should be 15% at the minimum pressure
location.=0A=C2- =C2- =C2-=A2 In the case of the Grumman wing,
it's closer to 14.88%. =C2-So, I only needed to thin the 64-415 wing a sc
hosh to make it fit better.=0A3) The spar is placed at the 34.55% MAC. =C2
-That is the location of minimum pressure.=0A=C2- =C2- =C2-
=A2 The shorter AA1 wing was closer to 40% given a 64-415 wing.=0A=C2-
=C2- =C2-=A2 Ideally, something like the 65-415 Comanche wing wit
h the minimum pressure at 50% would make a faster wing.=0A=C2- =C2- =C2
-=A2 The P-51 uses a 66-415 wing; i.e., minimum pressure is at 60%
of the chord.=0A=0AYou're more than welcome for the plots, Bob. =C2-I spe
nt 3 hours a day for 3 days measuring and remeasuring and then fine tuning
the plots to eliminate wiggles. =C2-=0A=0ANext step is to find a wing (wi
th data) that is close to the Grumman wing. =C2-So far, I've compared 671
airfoils to the Grumman airfoil. =C2-Some fit OK. =C2-Others are not e
ven close.=0A=0AIf I had unlimited cash flow, I'd hire the guys who built t
he last batch of AG5B wings to build me a set with the original airfoil.=0A
=0AGary=0A=0A=0A________________________________=0A From: Bob Steward <n76l
ima@mindspring.com>=0ATo: teamgrumman-list@matronics.com =0ASent: Wednesday
, December 7, 2011 2:01 PM=0ASubject: Re: TeamGrumman-List: Grumman Airfoil
ing.com>=0A=0A=0A> Attach 1:=C2- Grumman airfoil over layed on 64-415 at
presumed zero line.=0A> Attach 2:=C2- Grumman airfoil over layed on 64-41
5 at best fit.=0A> Attach 3:=C2- Grumman airfoil over layed on 63-415 at
presumed zero line.=C2- (a thinner airfoil)=0A> =0A> Bottom line is=0A> 1
) The airfoil is slightly thinner than what a computed 64-415 would be.=0A>
2) The forward flat portion of the wing is the reference angle.=0A=0AThe f
illed in trailing edge cusp on the Grumman airfoil vs. the NACA ones is com
mon, to reduce the loading on the controls.=C2- Basically a straight line
is drawn from the pivot point of the aileron (or flap) back to the trailin
g edge and the cusp is removed.=C2- You'll see this on nearly every produ
ction aircraft.=0A=0ALooks like they might have altered the point of max th
ickness to accommodate the spar tube, so that its center is near the 25% MA
C point, where torque is usually summed for calculations on the torsion box
for the built up spar designs.=0A=0AThanks for the excellent plots Gary.
- =C2- =C2- =C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Adm
- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- -Matt Dr
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Message 6
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| Subject: | Matronics Web Services Restored! |
Dear Listers,
I'm extremely happy to report that as of about 9pm PST 12/7, all of the Matronics
web services have been fully restored including the Web Forums, List Browse,
Archive Search, Wiki, and AeroElectric web sites. It was quite an ordeal getting
the replacement boards for the server, but things went back together tonight
and are up and running nicely. The first company I ordered the boards from
originally called me a day later to say that, whoops, they really didn't have
them in stock after all... Fortunately, I was able to locate some through
a different source and had then over-nighted and they arrived today.
Thank you for your patience and consideration though the whole thing!
The List Contribution web site is also back on line for those wishing to make a
donation to the effort:
http://www.matronics.com/contribution
Best regards,
Matt Dralle
Matronics List Administrator
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