Today's Message Index:
----------------------
0. 12:42 AM - The Value of a Forum... (Matt Dralle)
1. 10:16 AM - Re: Flying with a level (Gary Vogt)
2. 12:38 PM - Re: Aileron reflex (923te)
3. 12:43 PM - Stall Horn Warning Switch (923te)
4. 02:02 PM - Re: Stall Horn Warning Switch (Linn Walters)
5. 02:09 PM - Re: Stall Horn Warning Switch (923te)
6. 05:01 PM - Re: Stall Horn Warning Switch (Linn Walters)
7. 05:51 PM - Re: Stall Horn Warning Switch (923te)
8. 06:17 PM - Re: Stall Horn Warning Switch (flyv35b)
9. 06:31 PM - Re: Stall Horn Warning Switch (923te)
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| Subject: | The Value of a Forum... |
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Message 1
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| Subject: | Re: Flying with a level |
HS= horizontal stabilizer=0A=0AFrom what I've been able to determine,=C2
-=0A1. the wing is at 3 to 3.5 degrees up with respect to the fuselage.
=0A=C2- =A2 the wing needs some lift with the fuselage at 0 degrees
angle-of-attack (AOA).=0A=C2- =A2 as speed increases, lift increas
es on both the fuselage and wing. =C2-trim nose down.=0A2. the horizontal
stabilizer is at 0 degrees with respect to the fuselage.=0A=C2-
=A2 this is necessary for elevator response during landing angle-of-attack;
this is a compromise.=0A3. minimum drag AOA varies with depending on fuel
load, passenger loading, baggage compartment loading=0A=C2- =A2 the
ideal situation would be a battery mounted in the aft fuselage on a slide
so that it can be moved fore-aft to maintain minimum drag.=0A4. minimum dra
g AOA of the fuselage by itself is immaterial. =C2-The aircraft acts as a
system.=0A5. zero lift AOA of the wings, by themselves, is immaterial. =C2
-The aircraft acts as a system.=0A6. zero lift of the entire system depen
ds GREATLY on the airspeed.=0A=C2- =A2 as with 'Galloping Ghost,' y
ou will need to trim more nose down as speed goes above the design speed of
120 knots.=0A=C2- =C2- - Note: =C2-I say design speed based on what
I've measured and calculated. =C2-I do not know what speed, if any, the p
lane was designed.=0A6. I'm not convinced that minimum drag occurs when the
elevator is in trail with the horizontal stabilizer.=0A7. Looking for max
speed in my Cheetah, N9988U, I tried a lot of things. =C2-Full fuel, no p
assengers.=0A=C2- =A2 I setup all of the control surfaces, flaps, a
nd trim, as close as possible to zero degrees with respect to their parent
surface=0A=C2- =C2- =C2- (I removed the aileron trim and rudder trim)
=C2-=0A=C2- =C2- - this did not make the plane as fast as I eventuall
y got it=0A=C2- =A2 I set up the ailerons at +2 to +4 degrees up in
straight and level.=0A=C2- =C2- - this did not make the plane as fast
as I eventually got it=0A=C2- =A2 I set the flaps as high as +7 deg
rees up in straight and level=0A=0A=C2- =C2- - this did not make the pl
ane as fast as I eventually got it=0A=C2- =A2 I set up the elevator
trim at various setting with respect to the horizontal stabilizer.=0A=C2
- =C2- - any setting away from the stock setting had negligible effects
at speeds between 135 and 140 knots.=0A8. it was at this point that I star
ted looking at the individual systems as a complete system.=C2-=0A=C2-
=A2 it was also at this point that I began looking at other parts of
the plane to reduce drag.=0A=0A=0A=0A=0A________________________________=0A
From: "n76lima@mindspring.com" <n76lima@mindspring.com>=0ATo: 923TE@att.ne
t; bob.hodo@yahoo.com; teamgrumman@yahoo.com =0ASent: Saturday, November 19
, 2011 5:46 AM=0ASubject: Flying with a level=0A =0ANed brings up an intere
sting point.=C2- Flying with a level on or coordinated with the canopy ra
ils, such that one knows when the waterlines of the plane are lined up with
the actual "level" per the Earth's gravity might be significant.=0A=0AWhat
we don't know is what is the lowest drag attitude of the fuselage, since i
t isn't a symmetrical shape, and what is the zero lift angle of the wings,
since our airfoil has no NACA data and has never been blown on in the incre
asingly non-existent wind tunnels of this digital age.=0A=0AThat means that
flying with the canopy rails "level", and the elevator tips even with the
HS, can only be assumed to be the ideal from a drag reduction standpoint.
=0A=0AMaynard's assertion that the HS incidence is "0" seems odd, in that w
e know that the tail must provide down force to counter the wing's nose dow
n pitching moment.=C2- If set at Zero incidence, a symmetrical airfoil is
going to provide NO lift (up or down).=C2- If we can see that the elevat
or tips are in alignment with the HS in flight, we can also approximate the
trim tab location by centering the elevator, rolling the trim to the point
that the trim tabs are streamlined, and then marking the console to show t
he trim zero point.=0A=0AThe above should be considered in the context of t
he "zero" incidence is perhaps measured relative to the FUSELAGE, which is
not what matters.=C2- It is the incidence relative to the WING, which is
a measurement that I've never seen discussed.=C2- Somewhere in the deep d
ark recesses of FletchAir and now TrueFlight, there must be a drawing that
shows the incidence of the WING relative to the fuselage, and then one can
extrapolate the relative incidence of the HS to the wing.=C2- I submit th
at there is some difference in the angle of the wing and the tail.=C2- ie
: If the wing is rolled nose down to "zero" relative to level with respect
to the Earth, the fuselage is going to be pointing slightly nose down, so t
he elevator will have a leading edge down tilt with respect to the wing.=C2
- This is the "incidence" that matters, because the wing is the part gene
rating the force that the tail is trying to offset.=0A=0AThe tendency for t
he Grumman derived airfoil to "tuck" nose down as the plane flies faster ge
ts to the point that the airflow is now striking the tail at lower and lowe
r angle of attack (with the caveat that we know that the tail is "flying up
side down"), so the perceived angle of attack by the HS is increasing, and
at some point the elevators are reflexed trailing edge DOWN.=C2- This is
why Grummans have such great visibility forward in cruise, because unlike C
essna, Piper, Beech, the nose rotates down, making the cowl disappear and t
he view forward becomes unobstructed.=0A=0ASadly, we have what is essential
ly the Hortol STOL kit on our planes, which drops the zero lift line of the
wing to an even greater negative angle of attack, meaning that the fuselag
e has to rotate further nose down on an AA-1A/B/C and AA-5x than it does on
the AA-1 Yankee as the speed increases.=C2- Might this indicate that the
WING is set on the fuselage at the wrong angle of incidence relative to th
e angle of the least drag for the fuselage body's airflow?=C2- We may nev
er know, without means to blow on the fuselage shape at different angles of
attack.=0A=0ANed, perhaps you need the BD-8 style mod, where you can adjus
t the halves of the HS independently. <G>=C2- In case you didn't know, th
e BD-8 was Jim's idea for a serious aerobatic competitor, and it had a spli
t elevator that would be set in opposition to increase the rolling on the v
ertical line.=0A=0Ahttp://www.sportaviationspecialties.com/BD8.htm=0A=0AThe
re truly is nothing new under the sun.=0A=0A--Bob Steward=0AOccasional Crew
Chief to One Pretty Quick Cheetah
Message 2
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| Subject: | Re: Aileron reflex |
Gary,
When you were dive testing the Jag Cowl did you happen to
notice where your ailerons were riding? Mine ride higher that is
they reflex and by quite a bit. Scary actually...
A factory test pilot told me that was typical
Ned
Message 3
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| Subject: | Stall Horn Warning Switch |
Anyone have a suggestion as to how to seal the stall warning switch? I check
ed and mine leaks air. To me that means drag.
So I'll have to figure out how to seal it
Here is a picture of mine
Notice all the light coming in around it in the second pic?
With camera flash on
With camera flash off. see the light coming in?
>
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Message 4
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| Subject: | Re: Stall Horn Warning Switch |
Well, you could use some thin foam or some silicone. However, do you
really use the stall warning horn? If you're really after getting rid
of drag, I'd drop the switch inside and secure it in the other holes and
then fill up the hole in the leading edge.
Just a thought.
Linn
On 11/19/2011 3:41 PM, 923te wrote:
> Anyone have a suggestion as to how to seal the stall warning switch? I checked
and mine leaks air. To me that means drag.
> So I'll have to figure out how to seal it
>
> Here is a picture of mine
> Notice all the light coming in around it in the second pic?
Message 5
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| Subject: | Re: Stall Horn Warning Switch |
Not being an experimental I have to keep the stall switch working in place.
I may try the silicone or maybe a small amount of touch and foam???
I have not held and looked over the switch itself. I think the leak is outside
the switch. Anyone know if the switch itself leaks air thru it?
Sent from my iPhone
On Nov 19, 2011, at 3:58 PM, Linn Walters <pitts_pilot@bellsouth.net> wrote:
>
> Well, you could use some thin foam or some silicone. However, do you really
use the stall warning horn? If you're really after getting rid of drag, I'd drop
the switch inside and secure it in the other holes and then fill up the hole
in the leading edge.
> Just a thought.
> Linn
>
> On 11/19/2011 3:41 PM, 923te wrote:
>> Anyone have a suggestion as to how to seal the stall warning switch? I checked
and mine leaks air. To me that means drag.
>> So I'll have to figure out how to seal it
>>
>> Here is a picture of mine
>> Notice all the light coming in around it in the second pic?
>
>
>
>
>
Message 6
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| Subject: | Re: Stall Horn Warning Switch |
On 11/19/2011 5:06 PM, 923te wrote:
> --> TeamGrumman-List message posted by: 923te<923te@att.net>
>
> Not being an experimental I have to keep the stall switch working in place.
Well, only during the annual. ;-)
And it depends on what your goal really is.
> I may try the silicone or maybe a small amount of touch and foam???
>
> I have not held and looked over the switch itself. I think the leak is outside
the switch. Anyone know if the switch itself leaks air thru it?
From the pictures it looks like the switch rests in the black curved
(plastic or metal?) part. The light is leaking between the leading edge
metal and that black plastic part.
If there is drag, as you say, with that air leakage I suspect it's down
in the nano knot range. You might consider leaving the stall switch
alone 'till the last 'improvement'. The stall switches are pretty
pricey, I think.
Linn
>
> Sent from my iPhone
>
> On Nov 19, 2011, at 3:58 PM, Linn Walters<pitts_pilot@bellsouth.net> wrote:
>
>> --> TeamGrumman-List message posted by: Linn Walters<pitts_pilot@bellsouth.net>
>>
>> Well, you could use some thin foam or some silicone. However, do you really
use the stall warning horn? If you're really after getting rid of drag, I'd
drop the switch inside and secure it in the other holes and then fill up the hole
in the leading edge.
>> Just a thought.
>> Linn
>>
>> On 11/19/2011 3:41 PM, 923te wrote:
>>> Anyone have a suggestion as to how to seal the stall warning switch? I checked
and mine leaks air. To me that means drag.
>>> So I'll have to figure out how to seal it
>>>
>>> Here is a picture of mine
>>> Notice all the light coming in around it in the second pic?
>>
>>
>>
>>
>
>
Message 7
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| Subject: | Re: Stall Horn Warning Switch |
There is drag at the switch, loss of work from the air not going over
the wing surface and then drag created whne the air leaves the airframe.
It's interesting how some of the smallest shapes of the greatest drag.
Message 8
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| Subject: | Re: Stall Horn Warning Switch |
On 11/19/2011 5:56 PM, 923te wrote:
> There is drag at the switch, loss of work from the air not going over
> the wing surface and then drag created whne the air leaves the airframe.
> It's interesting how some of the smallest shapes of the greatest drag.
The drag from the switch has to be very very small. Spend your time
working on something that could make a real difference like cooling
drag. Design and build a cockpit adjustable cowl flap or some other way
to reduce cooling drag. At cruise speed you're dragging more air
through the engine compartment than you need, especially with cooler
weather.
Message 9
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| Subject: | Re: Stall Horn Warning Switch |
I agree and have a project in mind for the winter to try and reduce cooling drag.
Sent from my iPhone
On Nov 19, 2011, at 8:15 PM, flyv35b <flyv35b@minetfiber.com> wrote:
>
> On 11/19/2011 5:56 PM, 923te wrote:
>> There is drag at the switch, loss of work from the air not going over
>> the wing surface and then drag created whne the air leaves the airframe.
>> It's interesting how some of the smallest shapes of the greatest drag.
>
> The drag from the switch has to be very very small. Spend your time working
on something that could make a real difference like cooling drag. Design and
build a cockpit adjustable cowl flap or some other way to reduce cooling drag.
At cruise speed you're dragging more air through the engine compartment than
you need, especially with cooler weather.
>
>
>
>
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