Today's Message Index:
----------------------
1. 08:06 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (david miller)
2. 09:25 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (Fred Klein)
3. 10:32 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (Frans Veldman)
4. 11:12 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (Peter Zutrauen)
5. 11:43 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (Glenn Crowder)
6. 11:51 AM - Re: Effects of Flaps and Ailerons on Pitch Trim (Frans Veldman)
7. 12:06 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Frans Veldman)
8. 12:09 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (jimpuglise@comcast.net)
9. 12:19 PM - Re: Re: Electronic Mind Needed / It's Back! (JEFF ROBERTS)
10. 01:25 PM - Re: Re: Electronic Mind Needed / It's Back! (Greg Fuchs)
11. 01:28 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Mike Parkin)
12. 01:36 PM - Re: Re: Electronic Mind Needed / It's Back! (Frans Veldman)
13. 04:22 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Peter Zutrauen)
14. 05:29 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Frans Veldman)
15. 05:34 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Fred Klein)
16. 06:53 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Glenn Crowder)
17. 07:47 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (Dustin Clowser)
18. 08:55 PM - Re: Effects of Flaps and Ailerons on Pitch Trim (glenn crowder)
Message 1
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
Graham,
I think that for most efficient flight the incidence of the wing and
tail should be such that at cruise there is no up or down trim on the
elevator
or all flying tail.
seems to me that on my aircraft I am holding some down tail to
maintain level flight in cruise, if that is the case slightly less
incidence on the wing would have helped.
Again just going back to model days, to get a model to glide right
was a matter of altering the incidence on the wing or tail or adding
weight to the nose.
But that's about the extent of my aeronautical knowledge, I'm sure
brighter minds can correct this.
Dave
On 11-Apr-10, at 3:43 PM, GRAHAM SINGLETON wrote:
>
>
> From: Frans Veldman <frans@privatepilots.nl>
> To: europa-list@matronics.com
> Sent: Sunday, 11 April, 2010 16:59:05
> Subject: Re: Europa-List: Effects of Flaps and Ailerons on Pitch Trim
>
> <frans@privatepilots.nl>
> But the tail won't move, or the wing, just the fuselage.
> Does an all flying tail have an incidence at all?
> Graham
>
>
> On 04/11/2010 05:55 PM, david miller wrote:
> <loboloda@execulink.com>
> >
> > Frans,
> >
> > and the incidence of the fuselage will affect the incidence of the
> > tailplane.
>
> You are right.
>
> Frans
>
> _
>
>
Message 2
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
On Apr 12, 2010, at 6:24 AM, david miller wrote:
> I think that for most efficient flight the incidence of the wing and
> tail should be such that at cruise there is no up or down trim on
> the elevator or all flying tail.
Fascinating discussion...as a non-aerodynamicist, I can't resist the
temptation to add a comment...
I've always understood that the elevator or an all-flying tail
(horizontal tail plane) has a "job"...namely, to exert a force, either
up or down, in order to balance the lift of the wing and stabilize the
flight path of a normally configured aircraft (i.e., not a canard
type). To do this "job" requires "work"; the tail plane is never
neutral. And w/ our Europae...with it's trim tabs acting in
opposition to the all-flying tail plane thru a direct mechanical
connection...whenever the tail plane is doing its job (at whatever
angle of incidence), the trim tabs will be doing their job as well
(that of counterbalancing forces on the tailplane), and will
necessarily be raised or lowered w/ reference to the tailplane.
Of course if this explanation is correct, one might ponder the
aerodynamics of my tail-less biplane...pix below.
Fred
Message 3
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
On 04/12/2010 06:14 PM, Fred Klein wrote:
> I've always understood that the elevator or an all-flying tail
> (horizontal tail plane) has a "job"...namely, to exert a force, either
> up or down, in order to balance the lift of the wing and stabilize the
> flight path of a normally configured aircraft (i.e., not a canard type).
> To do this "job" requires "work"; the tail plane is never neutral.
I understood the tail plane of the Europa is aerodynamically neutral
indeed, and the sole function of the trim tabs is to give the pilot
tactile feedback and to push the tailplane in such a position that the
trim tab neutralizes itself again.
Without the trim tabs, the tail plane would be happy to remain in any
position where you set it, including in positions that pull excessive
G's. It is the trim tab that spoiles this neutrality and always tries to
work out a tail plane position where it can line up again with the tail
plane. So, the trim tab will always remain in the same relative position
of the tail plane regardless trim setting, but it is the whole
combination of tail plane and trim tab that change incidence as a whole
relatively to the main wings.
You might want to execute the following experiment:
Put a spring clamb on the trim tab and overlap it with the tail plane.
It should try to keep the tail plane and trim tab lined up.
Now carefully exercise the trim button and see what happens: It is not
the trim tab that moves, but the whole tailplane/trim tab combination!
This is what happens in flight as well. The clamb is no longer there,
but instead a flow of air over and under the trim tab, and as soon as
the trim tab tries to move outside the airflow, it will be pused back to
the tail plane, just as if there is a spring clamb on them.
This is true as long as you don't push or pull on the stick. As soon as
you do that, you will push or pull the trim tab out of its center, and
it becomes subject to a disbalance in air flow. It is the air pushing
against the trim tab what gives you the feeling of resistance when you
push or pull on the stick... As soon as you release the force, it will
rotate again to the same relative position.
Frans
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
This is an interesting subject indeed.
I was taught that on an inherently stable aircraft (operating within its CG
envelope) with a tail, the tailplane is always exerting a downward force in
cruise to counteract the tendency of the wing to twist forward in the
airflow due to the lift vector. As opposed to a canard where the forward
wing provides lift, making it a more efficient design.
I'm perplexed - all the photos I've ever looked at of Europas in cruise, the
trim tab is *up* (as others have noted), thus the flying elevator is by
definition providing *lift* to the tail.... a contradiction to my
teachings.
Confused,
Pete
A239
On Mon, Apr 12, 2010 at 12:14 PM, Fred Klein <fklein@orcasonline.com> wrote:
>
> On Apr 12, 2010, at 6:24 AM, david miller wrote:
>
> I think that for most efficient flight the incidence of the wing and tail
>> should be such that at cruise there is no up or down trim on the elevator or
>> all flying tail.
>>
>
> Fascinating discussion...as a non-aerodynamicist, I can't resist the
> temptation to add a comment...
>
> I've always understood that the elevator or an all-flying tail (horizontal
> tail plane) has a "job"...namely, to exert a force, either up or down, in
> order to balance the lift of the wing and stabilize the flight path of a
> normally configured aircraft (i.e., not a canard type). To do this "job"
> requires "work"; the tail plane is never neutral. And w/ our Europae...with
> it's trim tabs acting in opposition to the all-flying tail plane thru a
> direct mechanical connection...whenever the tail plane is doing its job (at
> whatever angle of incidence), the trim tabs will be doing their job as well
> (that of counterbalancing forces on the tailplane), and will necessarily be
> raised or lowered w/ reference to the tailplane.
>
> Of course if this explanation is correct, one might ponder the aerodynamics
> of my tail-less biplane...pix below.
>
> Fred
>
>
--
"A man is not old until his regrets take the place of his dreams. "
Message 5
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
The airfoil of the wing of any aircraft with a non symmetrical section will produce
a negative pitching moment (-cm) around the aerodynamic center of the wing.
This means that without the tailplane producing an equal but opposite moment
the acft will pitch over into a vertical dive. The all flying tailplane on
the Europa has no fixed angle of incidence so to produce an opposing positive
torque moment to the wings negative one the trim tab must be held out of plane.
At higher speeds then the tailplane must provide greater downforce then requiring
even more trim tab offset. We have to pay a small drag penalty to achieve
a level trim condition in cruise flight. This penalty can be reduced somewhat
by loading the acft towards the aft cg limits requiring less trim tab
offset reducing the downforce the tailplane must produce to maintain level flight.
The tailless flying wing derives it's pitch stability due to the outer portions
of the wing being reflexed up to produce that necessary positive pitching moment
but also introduces that small drag penalty again. There is no free lunch
in aerodynamics! Every desireable aerodynamic quality (like pitch stability)
has a price that must be paid.
Glenn
Fred Klein <fklein@orcasonline.com> wrote:
>
>On Apr 12, 2010, at 6:24 AM, david miller wrote:
>
>> I think that for most efficient flight the incidence of the wing and
>> tail should be such that at cruise there is no up or down trim on
>> the elevator or all flying tail.
>
>Fascinating discussion...as a non-aerodynamicist, I can't resist the
>temptation to add a comment...
>
>I've always understood that the elevator or an all-flying tail
>(horizontal tail plane) has a "job"...namely, to exert a force, either
>up or down, in order to balance the lift of the wing and stabilize the
>flight path of a normally configured aircraft (i.e., not a canard
>type). To do this "job" requires "work"; the tail plane is never
>neutral. And w/ our Europae...with it's trim tabs acting in
>opposition to the all-flying tail plane thru a direct mechanical
>connection...whenever the tail plane is doing its job (at whatever
>angle of incidence), the trim tabs will be doing their job as well
>(that of counterbalancing forces on the tailplane), and will
>necessarily be raised or lowered w/ reference to the tailplane.
>
>Of course if this explanation is correct, one might ponder the
>aerodynamics of my tail-less biplane...pix below.
>
>Fred
>
>
Message 6
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
On 04/12/2010 08:06 PM, Peter Zutrauen wrote:
> I was taught that on an inherently stable aircraft (operating within its
> CG envelope) with a tail, the tailplane is always exerting a downward
> force in cruise to counteract the tendency of the wing to twist forward
> in the airflow due to the lift vector. As opposed to a canard where
> the forward wing provides lift, making it a more efficient design.
I agree with this.
> I'm perplexed - all the photos I've ever looked at of Europas in cruise,
> the trim tab is *up* (as others have noted), thus the flying elevator is
> by definition providing *lift* to the tail.... a contradiction to my
> teachings.
I'm stating again: The position of the trim tab is NOT an indication of
the trim setting. The position of the trim tab is determined by the tail
plane... as you can easily see when you move the tailplane up or down.
The trim setting merely affects the tailplane position where the trim
tab is lined up with the tailplane. For the same relative position of
the trim tab to the tailplane, the whole tail plane has to move to a
different position if you change the trim setting.
The confusing part is that this position, where everything is in
balance, is not when the trim tab is lined out perfectly with the
tailplane. It is always somewhat UP, again regardless of trim setting.
The tailplane itself is designed as aerodynamically neutral: which means
that the tailplane won't favor a certain position by itself. Place it in
the airflow in any position you like... it won't rotate to a different
position.
This is where the trim tab comes into the equation. It artificially
makes the tailplane favor a certain position in the air stream.
The only thing I'm troubled with is that the stable rest position of the
tailplane plus trim tab is not when they are perfectly lined out in
relation to each other.
Maybe, just maybe, this may have something to do with the fact that the
hinges are on the upper side of the tailplane, rather than in the
center. The forces acting on the lower side have more leverage than the
forces acting on the upper side, hence the stable position of the trim
tab where all forces are cancelled out, is slightly up.
The more I think about this, the more I think that this is the reason
why we always see a trim tab up position.
Any comments about this hypothesis?
Frans
Message 7
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
On 04/12/2010 08:51 PM, Frans Veldman wrote:
> The more I think about this, the more I think that this is the reason
> why we always see a trim tab up position.
>
> Any comments about this hypothesis?
Anyone who reached the flying status interested in a harmless experiment?
My idea is that if you get the trim tab to line up with the tailplane
you will experience less drag.
There is a very easy way to achieve this: apply some nose UP trim, and
use your muscles to keep the stick in the desired (forward) position so
the nose doesn't move up.
This will have the effect that the trim tab moves down, and you prevent
the tailplane to get into a position where the trim tab sticks up again
by pushing the stick forward.
Of course you should try to remain at the same altitude.
If everything is right, you would see a small increase in speed.
I just wonder how much that is.
If it is worth the trouble, we could load the stick somewhat forward
with a spring or bungee. This would have the effect that the trimmed
position is always with the trim tab in line with the tailplane... as it
was supposed to be in the first place.
Frans
Message 8
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
As I remember my aerodynamics, the center of lift is always slightly aft of
the center of gravity, causing a tendency for the aircraft to pitch down i
f the elevator is discounted.=C2- The elevator therefor exerts a small do
wnward force on tail of the aircraft.=C2- This situation is reversed in a
cannard, which is why they are a little more efficient.=C2- Neither of t
hese relates in any way to the positon of the trim tab on the elevator.=C2
- I'd probably agree that the tab would cause less drag if it=C2-were i
n line with the rest of the elevator when at cruise speed.=C2- (I think t
his is the same thing Peter is saying.) =C2-
Jim Puglise A-283=C2-
----- Original Message -----
From: "Frans Veldman" <frans@privatepilots.nl>
Sent: Monday, April 12, 2010 2:51:09 PM GMT -05:00 US/Canada Eastern
Subject: Re: Europa-List: Effects of Flaps and Ailerons on Pitch Trim
On 04/12/2010 08:06 PM, Peter Zutrauen wrote:
> I was taught that on an inherently stable aircraft (operating within its
> CG envelope) with a tail, the tailplane is always exerting a downward
> force in cruise to counteract the tendency of the wing to twist forward
> in the airflow due to the lift vector. =C2- =C2-As opposed to a canar
d where
> the forward wing provides lift, making it a more efficient design.
I agree with this.
> I'm perplexed - all the photos I've ever looked at of Europas in cruise,
> the trim tab is *up* (as others have noted), thus the flying elevator is
> by definition providing *lift* to the tail.... a contradiction to my
> teachings.
I'm stating again: The position of the trim tab is NOT an indication of
the trim setting. The position of the trim tab is determined by the tail
plane... as you can easily see when you move the tailplane up or down.
The trim setting merely affects the tailplane position where the trim
tab is lined up with the tailplane. For the same relative position of
the trim tab to the tailplane, the whole tail plane has to move to a
different position if you change the trim setting.
The confusing part is that this position, where everything is in
balance, is not when the trim tab is lined out perfectly with the
tailplane. It is always somewhat UP, again regardless of trim setting.
The tailplane itself is designed as aerodynamically neutral: which means
that the tailplane won't favor a certain position by itself. Place it in
the airflow in any position you like... it won't rotate to a different
position.
This is where the trim tab comes into the equation. It artificially
makes the tailplane favor a certain position in the air stream.
The only thing I'm troubled with is that the stable rest position of the
tailplane plus trim tab is not when they are perfectly lined out in
relation to each other.
Maybe, just maybe, this may have something to do with the fact that the
hinges are on the upper side of the tailplane, rather than in the
center. The forces acting on the lower side have more leverage than the
forces acting on the upper side, hence the stable position of the trim
tab where all forces are cancelled out, is slightly up.
The more I think about this, the more I think that this is the reason
why we always see a trim tab up position.
Any comments about this hypothesis?
Frans
===========
===========
MS -
===========
e -
=C2- =C2- =C2- =C2- =C2--Matt Dralle, List Admin.
===========
Message 9
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| Subject: | Re: Electronic Mind Needed / It's Back! |
We'll my problem I thought I fixed is still there. After repairing the
connector and getting what I thought was good charging voltage to the
battery and flying for a few hours I just took the cowl off only to
double check my battery. Placed it on the charger and it's down to
35%. I started the plane and checked the voltage output from the
regulator and it's putting out 12.5. I'm starting to wonder if either
the regulator is working intermittently or if it could my 2 year old
odyssey battery? Looks like Sun-N-Fun will have to wait. I have
bypassed my panel with a voltage check by going to the 30 amp fuse
with a wire back to the battery and the voltage during running is the
same 12.5. If anyone has other Ideas or possibilities let me know but
I'm about to order a new battery. I guess if thats not it I'll have a
spare.
Jeff R. N128LJ Gold Rush
On Apr 8, 2010, at 9:57 AM, Bud Yerly wrote:
> Jeff,
> Let me pile on... Jim Brown and I have just gone through this.
> Frans is right on. The GG connections are AC.
> First confirm the voltage regulator is charging the battery. At
> 3000 RPM your ammeter should be near zero for a fully charged
> battery, and voltage should be 13.5-13.8 volts. If it is not, it is
> the stator or regulator.
> Regulator: Check the light circuit. Light on with engine off? It
> is supposed to be OK...Wrong, trust no light only.
> Check B+ again, with the alternator C and B connected it should be
> battery voltage, C is often put on an alternator switch, so check
> that the switch provides battery voltage.
> Check AC voltage from stator yellow leads. (see heavy mx manual
> 13.4.7).
> The regulator is a solid state device and does fail. $190 from
> Rotax. I used to keep a spare, but too expensive now.
>
> Stator:
> Check the resistance values of the stator yellow leads per the heavy
> maintenance manual. You need a good Volt/Ohm meter for this.
> If there is a short, then replacement of the stator is necessary. I
> have repaired them before, and a year later, I had to go in again
> and replace it. Yours is a fairly new engine, so you should not
> have a defective stator like I had. $1200 from Rotax.
>
> Enjoy your troubleshooting,
>
> Bud Yerly
> Custom Flight Creations.
>
> ----- Original Message -----
> From: JEFF ROBERTS
> To: europa-list@matronics.com
> Sent: Wednesday, April 07, 2010 11:21 PM
> Subject: Europa-List: Re: Electronic Mind Needed
>
>
>
> Hi All,
> My electronic problem is continuing to elude me. Thats not saying much
> since I have never wired anything except a room or two on some houses
> over the years. With that said I have been having trouble keeping my
> battery charged over the past 4 or 5 months. Gold Rush has 220
> delightful hours on her, but lately she's just not charging the
> battery, or maybe I have a drain somewhere that wasn't there before. I
> have replaced the regulator, and the big blue capacitor. After
> charging the battery today I went out and bought a new voltage meeter.
> I checked the battery 1st to be at 12.5 volts, I checked the 30 amp
> fuzes and they are good. Last week I did find a loose ground and fixed
> it but to no avail. Today I check the output of both alternator wires
> as they we're connected at the GG connections to the regulator and
> they we're reading - 6.5. when connected. When disconnected from the
> regulator they didn't have a reading at all. Is that normal?
> I also checked the +B output to see if it was sending a charge and it
> read only .53 volts.
> If any of you have advise to this non understanding electronics guy
> that would like to be flying charged to safely get to sun-n-fun let me
> know.
>
> Thanks In Advance!!
>
> Jeff R. N128LJ Gold p; Features Chat, http://
> www.matronnbsp; via the Web title=http://forums.matronics.com/
> href="http://forums.matronics.com">http://forums.matronics.com
> _p; generous bsp; title=http://
> www.matronics.com/contribution href="http://www.matronics.com/contribution
> ">http://www.matronics.com/c================
>
>
Message 10
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| Subject: | Re: Electronic Mind Needed / It's Back! |
Jeff,
An output of 12.5V from the regulator will certainly keep the battery in a
low state of charge(84% or below). This (sort of) falls in line with what
you are seeing with the battery state of charge per the charger, if the
engine rpm was not high enough to sustain the 12.5V from the (possibly
failed) regulator at all times (though I might expect the battery voltage to
track 12.5 a little better - 35% seems a little low). I assume that the
12.5V that you measured from the regulator was at a higher engine speed, and
not idle.
At this point, since your concern is a bad battery, I would check the
battery out of circuit (since it is easily done), by dis-connecting it from
the airplane, and charging it with an external charger (I think you are
doing that?). Charge it until the charger says that the battery has a full
charge, then disconnect the battery completely from the charger. At this
point, nothing is connected to the battery. Let the it sit for a day to
allow its voltage to drop (and stabilize), then measure the voltage on the
terminals to check that the state of charge is around 12.7V. If that is the
case, then the battery is maintaining a full state of charge. If you have
not had any starting problems with the aircraft (ie. plenty of juice to
crank the starter, in this higher state of charge), then I would say the
battery is good (rare cracked-post or related problems aside).
If the battery appears good, then all attention could now focus on the
regulator. If I were a betting man I would hedge my bets there.
Sorry to hear about Sun and Fun. That would be the hard part of it all.
Hope this helps,
Greg
off to do some errands...
We'll my problem I thought I fixed is still there. After repairing the
connector and getting what I thought was good charging voltage to the
battery and flying for a few hours I just took the cowl off only to double
check my battery. Placed it on the charger and it's down to 35%. I started
the plane and checked the voltage output from the regulator and it's putting
out 12.5. I'm starting to wonder if either the regulator is working
intermittently or if it could my 2 year old odyssey battery? Looks like
Sun-N-Fun will have to wait. I have bypassed my panel with a voltage check
by going to the 30 amp fuse with a wire back to the battery and the voltage
during running is the same 12.5. If anyone has other Ideas or possibilities
let me know but I'm about to order a new battery. I guess if thats not it
I'll have a spare.
Jeff R. N128LJ Gold Rush
Message 11
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| Subject: | Effects of Flaps and Ailerons on Pitch Trim |
I suppose where the confusion comes here is the fact that there are 2 things
going on here..... a trim system overlaying an anti-servo system. In a
conventional trim system the trim tab will retain its offset position if
that is where you leave it. Not so with an all flying tail where the neutral
is effectively changed - with the trim system in the europa. In a powered
all flying tail, the feel system is often used to move the effective
neutral.
Regards,
MP
Do not archive.
Message 12
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| Subject: | Re: Electronic Mind Needed / It's Back! |
On 04/12/2010 09:18 PM, JEFF ROBERTS wrote:
> If
> anyone has other Ideas or possibilities let me know but I'm about to
> order a new battery. I guess if thats not it I'll have a spare.
It is not your battery.
A battery is a bad spare to have. Just from being a "spare" they will
age prematurely.
Frans
Message 13
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
Hi Glenn,
that was my understanding as well - but when trimmed for cruise, wouldn't
the anti-servo/trim-tab be required to portrude *downwards* to drive the
trailing edge of the tailplane *up* to result in the equivalent of pulling
back on the stick, to have the tailplane produce the required downward
force on the tail?
All the pics I've seen show the trimtab portruding *up*, ie, trim = foward
stick..... no?
Still confused,
Pete
A239
On Mon, Apr 12, 2010 at 2:41 PM, Glenn Crowder <gcrowder2@hotmail.com>wrote:
>
> The airfoil of the wing of any aircraft with a non symmetrical section will
> produce a negative pitching moment (-cm) around the aerodynamic center of
> the wing. This means that without the tailplane producing an equal but
> opposite moment the acft will pitch over into a vertical dive. The all
> flying tailplane on the Europa has no fixed angle of incidence so to produce
> an opposing positive torque moment to the wings negative one the trim tab
> must be held out of plane. At higher speeds then the tailplane must provide
> greater downforce then requiring even more trim tab offset. We have to pay
> a small drag penalty to achieve a level trim condition in cruise flight.
> This penalty can be reduced somewhat by loading the acft towards the aft cg
> limits requiring less trim tab offset reducing the downforce the tailplane
> must produce to maintain level flight.
>
> The tailless flying wing derives it's pitch stability due to the outer
> portions of the wing being reflexed up to produce that necessary positive
> pitching moment but also introduces that small drag penalty again. There is
> no free lunch in aerodynamics! Every desireable aerodynamic quality (like
> pitch stability) has a price that must be paid.
>
> Glenn
>
> Fred Klein <fklein@orcasonline.com> wrote:
>
> >
> >On Apr 12, 2010, at 6:24 AM, david miller wrote:
> >
> >> I think that for most efficient flight the incidence of the wing and
> >> tail should be such that at cruise there is no up or down trim on
> >> the elevator or all flying tail.
> >
> >Fascinating discussion...as a non-aerodynamicist, I can't resist the
> >temptation to add a comment...
> >
> >I've always understood that the elevator or an all-flying tail
> >(horizontal tail plane) has a "job"...namely, to exert a force, either
> >up or down, in order to balance the lift of the wing and stabilize the
> >flight path of a normally configured aircraft (i.e., not a canard
> >type). To do this "job" requires "work"; the tail plane is never
> >neutral. And w/ our Europae...with it's trim tabs acting in
> >opposition to the all-flying tail plane thru a direct mechanical
> >connection...whenever the tail plane is doing its job (at whatever
> >angle of incidence), the trim tabs will be doing their job as well
> >(that of counterbalancing forces on the tailplane), and will
> >necessarily be raised or lowered w/ reference to the tailplane.
> >
> >Of course if this explanation is correct, one might ponder the
> >aerodynamics of my tail-less biplane...pix below.
> >
> >Fred
> >
> >
> >
> >
>
>
--
"A man is not old until his regrets take the place of his dreams. "
Message 14
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
On 04/13/2010 01:19 AM, Peter Zutrauen wrote:
> that was my understanding as well - but when trimmed for cruise,
> wouldn't the anti-servo/trim-tab be required to portrude *downwards* to
> drive the trailing edge of the tailplane *up*
Read again what you just said. If the trailing edge of the tailplane
moves up, the trim tab moves up even more. It *always* goes back to the
same stabile position, regardless of trim setting. The only difference
is that this stabile position is achieven by a different tailplane
incidence. This is how it works: you trim it down, it drives the
tailplane up, this will take the trim tab up even more, counteracting
what you just did... and the nett effect is that the tailplane's
trailing edge has moved up. This is how a anti-servo tab works.
> to result in the
> equivalent of pulling back on the stick,
Pulling back on the stick is not the equivalent. If you pull on the
stick, the trim tab won't revert to its stabile aerodynamic position...
and that is why you need to keep pulling on the stick, to counteract the
forces on the trim tab.
> to have the tailplane produce
> the required downward force on the tail?
Actually, it is not a trim tab, but an anti-servo trim tab. It works
differently.
> All the pics I've seen show the trimtab portruding *up*, ie, trim
> foward stick..... no?
The *only* conclusion you can draw from the trimtab protruding up, is
that its stabile position is upwards relative to the tailplane. This
will remain the same for all trim settings. If you change the trim, the
only nett effect is that the tailplane will move to a different
incidence... but the trim tab will remain at the same position. Play
with it on the ground, until you see what's happening.
Frans
Message 15
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
Gentlemen,
Help me wipe the egg off my face...delete my last post...w/ our
Europas, we're talkin anti-servo tabs, not trim tabs...my apologies
for riffing on trim tabs before engaging my brain...
Fred
Message 16
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
Peter Zutrauen <peterz@zutrasoft.com> wrote:
>Hi Glenn,
>
>that was my understanding as well - but when trimmed for cruise, wouldn't
>the anti-servo/trim-tab be required to portrude *downwards* to drive the
>trailing edge of the tailplane *up* to result in the equivalent of pulling
>back on the stick, to have the tailplane produce the required downward
>force on the tail?
>
>All the pics I've seen show the trimtab portruding *up*, ie, trim = foward
>stick..... no?
>
>Still confused,
>Pete
>A239
>
>
>On Mon, Apr 12, 2010 at 2:41 PM, Glenn Crowder <gcrowder2@hotmail.com>wrote:
>
>>
>> The airfoil of the wing of any aircraft with a non symmetrical section will
>> produce a negative pitching moment (-cm) around the aerodynamic center of
>> the wing. This means that without the tailplane producing an equal but
>> opposite moment the acft will pitch over into a vertical dive. The all
>> flying tailplane on the Europa has no fixed angle of incidence so to produce
>> an opposing positive torque moment to the wings negative one the trim tab
>> must be held out of plane. At higher speeds then the tailplane must provide
>> greater downforce then requiring even more trim tab offset. We have to pay
>> a small drag penalty to achieve a level trim condition in cruise flight.
>> This penalty can be reduced somewhat by loading the acft towards the aft cg
>> limits requiring less trim tab offset reducing the downforce the tailplane
>> must produce to maintain level flight.
>>
>> The tailless flying wing derives it's pitch stability due to the outer
>> portions of the wing being reflexed up to produce that necessary positive
>> pitching moment but also introduces that small drag penalty again. There is
>> no free lunch in aerodynamics! Every desireable aerodynamic quality (like
>> pitch stability) has a price that must be paid.
>>
>> Glenn
>>
>> Fred Klein <fklein@orcasonline.com> wrote:
>>
>> >
>> >On Apr 12, 2010, at 6:24 AM, david miller wrote:
>> >
>> >> I think that for most efficient flight the incidence of the wing and
>> >> tail should be such that at cruise there is no up or down trim on
>> >> the elevator or all flying tail.
>> >
>> >Fascinating discussion...as a non-aerodynamicist, I can't resist the
>> >temptation to add a comment...
>> >
>> >I've always understood that the elevator or an all-flying tail
>> >(horizontal tail plane) has a "job"...namely, to exert a force, either
>> >up or down, in order to balance the lift of the wing and stabilize the
>> >flight path of a normally configured aircraft (i.e., not a canard
>> >type). To do this "job" requires "work"; the tail plane is never
>> >neutral. And w/ our Europae...with it's trim tabs acting in
>> >opposition to the all-flying tail plane thru a direct mechanical
>> >connection...whenever the tail plane is doing its job (at whatever
>> >angle of incidence), the trim tabs will be doing their job as well
>> >(that of counterbalancing forces on the tailplane), and will
>> >necessarily be raised or lowered w/ reference to the tailplane.
>> >
>> >Of course if this explanation is correct, one might ponder the
>> >aerodynamics of my tail-less biplane...pix below.
>> >
>> >Fred
>> >
>> >
>> >
>> >
>>
>>
>>
>>
>>
>>
>
>
>--
>"A man is not old until his regrets take the place of his dreams. "
Message 17
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| Subject: | Re: Effects of Flaps and Ailerons on Pitch Trim |
304.904.3850=0A=0A=0A=0A=0A________________________________=0AFrom: Glenn C
rowder <gcrowder2@hotmail.com>=0ATo: europa-list@matronics.com=0ASent: Mon,
April 12, 2010 9:36:43 PM=0ASubject: Re: Europa-List: Effects of Flaps and
er <gcrowder2@hotmail.com>=0A=0A=0A=0APeter Zutrauen <peterz@zutrasoft.com>
wrote:=0A=0A>Hi Glenn,=0A>=0A>that was my understanding as well - but when
trimmed for cruise, wouldn't=0A>the anti-servo/trim-tab be required to por
trude *downwards* to drive the=0A>trailing edge of the tailplane *up* to re
sult in the equivalent of pulling=0A>back on the stick,- to have the tail
plane produce the required downward=0A>force on the tail?=0A>=0A>All the pi
cs I've seen show the trimtab portruding *up*, ie, trim- = foward=0A>st
ick..... no?=0A>=0A>Still confused,=0A>Pete=0A>A239=0A>=0A>=0A>=0A>On Mon,
Apr 12, 2010 at 2:41 PM, Glenn Crowder <gcrowder2@hotmail.com>wrote:=0A>=0A
=0A>>=0A>> The airfoil of the wing of any aircraft with a non symmetrical s
ection will=0A>> produce a negative pitching moment (-cm) around the aerody
namic center of=0A>> the wing.- This means that without the tailplane pro
ducing an equal but=0A>> opposite moment the acft will pitch over into a ve
rtical dive.- The all=0A>> flying tailplane on the Europa has no fixed an
gle of incidence so to produce=0A>> an opposing positive torque moment to t
he wings negative one the trim tab=0A>> must be held out of plane.- At hi
gher speeds then the tailplane must provide=0A>> greater downforce then req
uiring even more trim tab offset.- We have to pay=0A>> a small drag penal
ty to achieve a level trim condition in cruise flight.=0A>> This penalty ca
n be reduced somewhat by loading the acft towards the aft cg=0A>> limits re
quiring less trim tab offset reducing the downforce the tailplane=0A>> must
produce to maintain level flight.=0A>>=0A>>- The tailless flying wing de
rives it's pitch stability due to the outer=0A>> portions of the wing being
reflexed up to produce that necessary positive=0A>> pitching moment but al
so introduces that small drag penalty again.- There is=0A>> no free lunch
in aerodynamics!- Every desireable aerodynamic quality (like=0A>> pitch
stability) has a price that must be paid.=0A>>=0A>>- - - - - -
- - - - - - - - - - - Glenn=0A>>=0A>> Fred Klein <fkl
ein@orcasonline.com> wrote:=0A>>=0A>> >=0A>> >On Apr 12, 2010, at 6:24 AM,
david miller wrote:=0A>> >=0A>> >> I think that for most efficient flight t
he incidence of the wing and=0A>> >> tail should be such that at cruise the
re is no up or down trim on=0A>> >> the elevator or all flying tail.=0A>> >
=0A>> >Fascinating discussion...as a non-aerodynamicist, I can't resist the
=0A>> >temptation to add a comment...=0A>> >=0A>> >I've always understood t
hat the elevator or an all-flying tail=0A>> >(horizontal tail plane) has a
"job"...namely, to exert a force, either=0A>> >up or down, in order to bala
nce the lift of the wing and stabilize the=0A>> >flight path of a normally
configured aircraft (i.e., not a canard=0A>> >type). To do this "job" requi
res "work"; the tail plane is never=0A>> >neutral.- And w/ our Europae...
with it's trim tabs acting in=0A>> >opposition to the all-flying tail plane
thru a direct mechanical=0A>> >connection...whenever the tail plane is doi
ng its job (at whatever=0A>> >angle of incidence), the trim tabs will be do
ing their job as well=0A>> >(that of counterbalancing forces on the tailpla
ne), and will=0A>> >necessarily be raised or lowered w/ reference to the ta
ilplane.=0A>> >=0A>> >Of course if this explanation is correct, one might p
onder the=0A>> >aerodynamics of my tail-less biplane...pix below.=0A>> >=0A
>> >Fred=0A>> >=0A>> >=0A>> >=0A>> >=0A>>=0A>>=0A>>=0A>>=0A>>=0A>>=0A>=0A>
=0A>-- =0A>"A man is not old until his regrets take the place of his dreams
==================0A=0A=0A
Message 18
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| Subject: | Effects of Flaps and Ailerons on Pitch Trim |
OK Pete - the tailplane is ALWAYS pushing down at all airspeeds but at high
er airspeeds the wing is at a very low angle of attack. As the airspeed go
es up=2C the
aerodynamic forces on all control surfaces (ailerons=2C rudder=2C tailplane
) go up by the
SQUARE of airspeed. This is why you cannot give full control deflection at
VNE=2C the
control surfaces will depart the aircraft. So when the wing goes to a very
low angle
of attack=2C the tail must also. The tail is still flying at a negative an
gle of attack but
it is very small. However this small negative angle of attack is generatin
g a lot of
positive CM because of the high airspeed. To get this slightly negative an
gle of attack
at a high airspeed requires a lot of force and this is generated by the UP
position of
the trimtab forcing the trailing edge of the tailplane DOWN. The trim tab
controls the
angle of attack of the tail (always negative but less negative at high spee
d)=2C the
anti servo system keeps the tail at the set angle of attack. Other factors
come into
play here such as the angle of relative airflow from the wing downwash. Th
e tail
may look as though it has a positive angle of attack but because of the win
g downwash=2C the relative airflow is actually hitting it from above. This
angle becomes less at high speeds but the forces go up with the square of
airspeed.
at high speeds
Subject: Re: Europa-List: Effects of Flaps and Ailerons on Pitch Trim
From: peterz@zutrasoft.com
Hi Glenn=2C
that was my understanding as well - but when trimmed for cruise=2C wouldn't
the anti-servo/trim-tab be required to portrude *downwards* to drive the t
railing edge of the tailplane *up* to result in the equivalent of pulling b
ack on the stick=2C to have the tailplane produce the required downward fo
rce on the tail?
All the pics I've seen show the trimtab portruding *up*=2C ie=2C trim =
foward stick..... no?
Still confused=2C
Pete
A239
On Mon=2C Apr 12=2C 2010 at 2:41 PM=2C Glenn Crowder <gcrowder2@hotmail.com
> wrote:
The airfoil of the wing of any aircraft with a non symmetrical section will
produce a negative pitching moment (-cm) around the aerodynamic center of
the wing. This means that without the tailplane producing an equal but op
posite moment the acft will pitch over into a vertical dive. The all flyin
g tailplane on the Europa has no fixed angle of incidence so to produce an
opposing positive torque moment to the wings negative one the trim tab must
be held out of plane. At higher speeds then the tailplane must provide gr
eater downforce then requiring even more trim tab offset. We have to pay a
small drag penalty to achieve a level trim condition in cruise flight. T
his penalty can be reduced somewhat by loading the acft towards the aft cg
limits requiring less trim tab offset reducing the downforce the tailplane
must produce to maintain level flight.
The tailless flying wing derives it's pitch stability due to the outer por
tions of the wing being reflexed up to produce that necessary positive pitc
hing moment but also introduces that small drag penalty again. There is no
free lunch in aerodynamics! Every desireable aerodynamic quality (like pi
tch stability) has a price that must be paid.
Glenn
Fred Klein <fklein@orcasonline.com> wrote:
>
>On Apr 12=2C 2010=2C at 6:24 AM=2C david miller wrote:
>
>> I think that for most efficient flight the incidence of the wing and
>> tail should be such that at cruise there is no up or down trim on
>> the elevator or all flying tail.
>
>Fascinating discussion...as a non-aerodynamicist=2C I can't resist the
>temptation to add a comment...
>
>I've always understood that the elevator or an all-flying tail
>(horizontal tail plane) has a "job"...namely=2C to exert a force=2C either
>up or down=2C in order to balance the lift of the wing and stabilize the
>flight path of a normally configured aircraft (i.e.=2C not a canard
>type). To do this "job" requires "work"=3B the tail plane is never
>neutral. And w/ our Europae...with it's trim tabs acting in
>opposition to the all-flying tail plane thru a direct mechanical
>connection...whenever the tail plane is doing its job (at whatever
>angle of incidence)=2C the trim tabs will be doing their job as well
>(that of counterbalancing forces on the tailplane)=2C and will
>necessarily be raised or lowered w/ reference to the tailplane.
>
>Of course if this explanation is correct=2C one might ponder the
>aerodynamics of my tail-less biplane...pix below.
>
>Fred
>
>
=======================
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