Hi Tim,

I tested your rudder during bank question this past weekend in my Tri-Q2
with an LS1 canard with anhedral and standard rudder. I was doing laps
around the pattern and building up landings and remembered your post.
So while banking to the left on crosswind to downwind, I applied right
rudder and the plane leveled off to the right as you were expecting. I
did it twice to make sure of the results. I did not get the sense that
I was yawing. It felt more like I had used the ailerons to roll out.

I hope that was the feedback you were looking for. I know Earnest
reported similar results as well.

Maybe you've got one of those dad'burn rudders that are too big! <grin>
All kidding aside, something must be up for you to get the results you
are describing.

I don't recall consciously using the rudder like that in a bank before.
It makes all the more sense now why the instructors harp on it so much
to fly coordinated especially in a bank and not be lazy on the rudders.
I was talking with Earnest about rudders at Emporia and how I noticed
during the ride out that it seems like you always have to keep an eye on
the ball. Any change in pitch or roll or throttle you make seems to
result in the ball being off center. One thing I also noticed was how
easy it was to hear when the ball was off center. I'm guessing it was
the sound of the air rushing in the NACA vents that I was noticing that
changed in intensity when I would be even slightly slipping or skidding.
The rudder on this plane seems like it is a one legged stool where you
just can't set and forget but you always have to keep on top of it.

Good luck tracking down your problems.

Dave Richardson
Tri-Q2 825DR

Hi Tim

As a matter of interest, all aircraft become increasingly pitch sensitive as the C of G travels aft, that is why there is an aft limit.
There is a safety factor built in, of course, but, generally speaking, to be behind that limit is dangerous.
The further forward the C of G is, the more pitch stable the aircraft is, at the expense of elevator authority, which is why there is a forward limit.

Would I be correct in thinking that you do not have any sparrow strainers installed?

Regards

Paul Buckley
Cheshire
England.

TriQ200....still building.

It is interesting to discover differences in the Q and Dragonfly as these
discussions come up. The Dragonfly's rudder is very effective, in fact the
rudder is way more effective than the ailerons in rolling my Dragonfly....of
course the Dragonfly probably has twice the rudder area. As the airspeed
builds in the Dragonfly the aileron controls forces get very heavy, this is
a problem that the Q does not seem to have. Lots of Dragonfly's have
aileron servo tabs to reduce the aileron stick pressure.

Like Jim's experience, my Dragonfly is more pitch sensitive with an aft CG.
I have adjustable sparrow strainers on my Dragonfly (GU canard) and a simple
2 spring elevator trim system. If I run out of up elevator trim I need to
put more AOA in the sparrow strainers. The faster the airspeed the more the
elevator wants to come up. Using a digital level; with the upper surface of
the elevator at 45 degrees down (not travel, just the static position) the
upper surface of my sparrow strainers are at 38 degrees down. A 2-3 degree
adjustment of the sparrow strainers makes a significant difference, in fact
I have been able to correct for a slight roll tendency with one sparrow
strainer that is set ever so slightly different that the other one.

This sparrow strainer setting works for my current cruise airspeed of about
140 MPH. My elevator trim system does not have a wide adjustment range and
I have found that the 5-7 MPH airspeed difference with my wheel pants
requires a sparrow strainer adjustment. I can adjust for hands-off with the
reflexor if I run out of elevator trim, but the elevator will not be in
trail. I can either install larger springs, install a different trim system
that has more travel, or make minor sparrow strainer adjustments when I make
aerodynamic adjustments that will effect my cruise airspeed. I will
probably opt for the minor sparrow strainer adjustments, but a trim system
with more range is the right answer (and there are even plans in an old
Dragonfly newsletter)....maybe I am getting lazy.

I know very little of this information could be directly applied to a Q, but
you never know. Obviously you should listen to what the experienced Q guys
have to say. Good luck.

Jeff

Jeff,
Not all Q's are like the one described that would not lift a wing with
rudder. My plane easily lifts a wing with rudder. When I want to fold a map I
get on the rudder so my hands are free. A few years back, before I put my
pitch trim switch on the stick, I flew it for 30 minutes without touching the
stick using pitch trim and rudder. That was on an average summer day with
average turbulence. I could have done it all day but 30 minutes gave me the info I
wanted.
I don't know if not having anhedral on the canard makes a difference or
not. Maybe anhedral on the canard partially cancels the dihedral of the wing.
It's amazing how many differences we find in the same design with different
builders.

Earnest
Triq200 960 hrs

Allan
I have sent you a few pix of your Q2 showing a side view. I'll do a CD of all the Pix I have of your A/C and post iot to you. Send me your address again.
neil



Allan Farr wrote:

From what I understand it depends on how much filler is used on the glass-to-glass join at the trailing edge. If none is used, there is quite a lip. However even allowing for that, my elevators may not have been constructed totally accurately as otherwise flipping them over would have been a lot easier.
AF

Will do - I'll let you know when it's done, probably next week before I can get hold of a camera.
Allan

Allan,

I don't think there's supposed to be any curve at all in the GU elevators.
My plans don't show any.


David J. Gall

Cap'n Dan,

They look like
someone didn't design something right and they had to add a fix.

BINGO! Well, not quite. Airfoil choices are a compromise and sometimes a
band-aid is needed to make a particular choice work in a particular
application. The LS(1) airfoil wasn't the only choice at the time, but it
had a goodly amount of marketing hype propelling it along in the early
'80's. We've since learned that its not such a hot GA airfoil after all, but
for a high wing loading (like on a Q200 canard) it is one of the "good"
choices. Unfortunately, its trailing edge is curved just the wrong way for a
canard elevator.

Strainers are one possible solution to fix such a problem, but not the best
for the hangar-rash issues you mention, among others. The advantage of the
strainers is that they have a long leverage arm behind the elevator hinge
line. You could use a fixed trim tab instead, but it would have to be pretty
large since it would be closer to the hinge line. See the Long-EZ "new"
canard with the Roncz 1145MS airfoil for the correct way to do it. Roncz
essentially designed a fixed trim tab into the airfoil along the entire span
of the elevator. Most people don't even notice that it is there, but it is.
It is "tweaked" so that the elevator's natural "floating" angle of
deflection is appropriate for a low cruise speed for the airplane without
any trim system or control system forces being applied. Your strainers
should be adjusted similarly, if the designers and builders did their jobs
right.

Meanwhile, since no one has adapted the Roncz airfoil to the Q-birds, I
recommend that you keep the strainers and follow the advice offered on this
list, especially the advice to have some experienced sets of eyes look over
your plane. I suspect you've got a problem with your strainers or maybe even
with the construction of your elevators.


David J. Gall
P.S. an anti-servo tab could be adapted, but it would only be flush at one
elevator deflection, likely close to full "up" elevator (trailing edge
down). Tabs, by their very nature, are not "flush."

-----Original Message-----
From: Q-LIST@... [mailto:Q-LIST@...]
On Behalf Of Danny Creech
Sent: Wednesday, October 18, 2006 10:13 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Flight characteristics questions

< snip! >

2. More important though is: Are there any other ways to
fix this problem without having to put sparrow strainers on??
They increase drag, stick out being easy to damage from
airshow goers, and all in all they look ugly. They look like
someone didn't design something right and they had to add a fix.

Has anyone came up with some other way to fix this problem?
Is this problem only on the LS1 wing or do all of the Q2s and
Q200s have this problem? Would making a flush mounted tab
(anti-servo or something) into the elevator work?

,___
Capt. Danny Creech
^^ Not an aerodynamic engineer obviously.

Allen - can you take some photos and post them to the photos folder?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

David,
The elevators on my GU canard appeared to me to have been put on upside down by the original builder as the trailing edge curved up. I have gone to alot of trouble flipping them over so that the t/e curves down - do you think I should have left them as is?
Allan Farr
Q2
P.S. On fast taxi runs with the elevators as they were (t/e curved up), the canard didn't want to fly. I need all the lift I can get up front, and that is one reason why I flipped the elevators over.

Yeah, stupid me. I knew I was going to get it on this one. GRIN

Danny Creech

Jim Patillo <logistics_engineering@...> wrote:


Danny,

When you pull the stick back on a Q in flight, the elevator is
deflected down and the result is the nose goes up. Its a canard.

Jim Patillo

--- In Q-LIST@..., Danny Creech <dannycreech@...> wrote:

"David J. Gall" <David@...> wrote:
Without sparrow strainers, when the airplane inadvertently goes

faster than

its trimmed airspeed, the slight undercamber of the LS(1) elevator

causes

aerodynamic force that pushes the trailing edge of the elevator

up. This

lets the airplane's nose come down and allows the airplane to

accelerate to

a yet-higher speed. NOT GOOD!


Couple of points here.

1. If the TRAILING edge of an elevator goes up, then the nose of

the aircraft goes up. Not down. I re-read David's post several times
just to make sure I wasn't missing something.

2. More important though is: Are there any other ways to fix

this problem without having to put sparrow strainers on?? They
increase drag, stick out being easy to damage from airshow goers,
and all in all they look ugly. They look like someone didn't design
something right and they had to add a fix.

Has anyone came up with some other way to fix this problem? Is

this problem only on the LS1 wing or do all of the Q2s and Q200s
have this problem? Would making a flush mounted tab (anti-servo or
something) into the elevator work?

,___
Capt. Danny Creech
^^ Not an aerodynamic engineer obviously.

Darn if your not right! As soon as you responded I thought about it and it only makes since! Sheeesh. I guess that is why I leave all the design to the engineers and I just fly them. <GRIN>

I just know I'm going to get drug through the mud for making that statment!

I guess I'm just not used to the tail being upfront where it belongs.

Your a funny guy Jon.

Danny Creech


>Not on our airplanes... . Elevator trailing edge up = nose down. Elevator
trailing edge down = nose up. David wrote it correctly.

This plus the fact that stick left = right roll and vice versa are the
reason that these planes are so hard to fly. ;-) (kidding about the roll
thing)

Jon Finley
N90MG - Q2 - Subaru EJ-22 Legacy

Not on our airplanes.... Elevator trailing edge up = nose down. Elevator
trailing edge down = nose up. David wrote it correctly.

This plus the fact that stick left = right roll and vice versa are the
reason that these planes are so hard to fly. ;-) (kidding about the roll
thing)

Jon Finley
N90MG - Q2 - Subaru EJ-22 Legacy
http://www.finleyweb.net/Q2Subaru
Mid-Valley Airpark, Los Lunas, NM

Not this elevator.........it's at the front!

Danny,

When you pull the stick back on a Q in flight, the elevator is
deflected down and the result is the nose goes up. Its a canard.

Jim Patillo

--- In Q-LIST@..., Danny Creech <dannycreech@...> wrote:

"David J. Gall" <David@...> wrote:

>Without sparrow strainers, when the airplane inadvertently goes

faster than

its trimmed airspeed, the slight undercamber of the LS(1) elevator

causes

aerodynamic force that pushes the trailing edge of the elevator

up. This

lets the airplane's nose come down and allows the airplane to

accelerate to

a yet-higher speed. NOT GOOD!


Couple of points here.

1. If the TRAILING edge of an elevator goes up, then the nose of

the aircraft goes up. Not down. I re-read David's post several times
just to make sure I wasn't missing something.

2. More important though is: Are there any other ways to fix

this problem without having to put sparrow strainers on?? They
increase drag, stick out being easy to damage from airshow goers,
and all in all they look ugly. They look like someone didn't design
something right and they had to add a fix.

Has anyone came up with some other way to fix this problem? Is

this problem only on the LS1 wing or do all of the Q2s and Q200s
have this problem? Would making a flush mounted tab (anti-servo or
something) into the elevator work?

,___
Capt. Danny Creech
^^ Not an aerodynamic engineer obviously.

"David J. Gall" <David@...> wrote:

>Without sparrow strainers, when the airplane inadvertently goes faster than
its trimmed airspeed, the slight undercamber of the LS(1) elevator causes
aerodynamic force that pushes the trailing edge of the elevator up. This
lets the airplane's nose come down and allows the airplane to accelerate to
a yet-higher speed. NOT GOOD!


Couple of points here.

1. If the TRAILING edge of an elevator goes up, then the nose of the aircraft goes up. Not down. I re-read David's post several times just to make sure I wasn't missing something.


2. More important though is: Are there any other ways to fix this problem without having to put sparrow strainers on?? They increase drag, stick out being easy to damage from airshow goers, and all in all they look ugly. They look like someone didn't design something right and they had to add a fix.

Has anyone came up with some other way to fix this problem? Is this problem only on the LS1 wing or do all of the Q2s and Q200s have this problem? Would making a flush mounted tab (anti-servo or something) into the elevator work?

,___
Capt. Danny Creech
^^ Not an aerodynamic engineer obviously.

Danny,
This is not a common problem. In fact yours is the first I have heard
of. It sounds to me like something is wrong with you sparrow strainers ( a
minor fix). But, I would not fly it until you figure it out. Where are you
located? Maybe another builder could help you trouble shot it.
Earnest
Triq200 960 hours

Paul,

Not underneath. On top. It is UNdesirable to have undercambered
elevators on canards. It IS desireable to have a slight REFLEX (reverse
camber near the trailing edge) on the elevators of canard airplanes.
This is one distinct reason that the choice of the LS(1)-0417MOD
airfoil was such a POOR CHOICE for a canard airfoil, despite the fact
that it has been made to work. IIRC, the LS(1) canard was rumored to be
the breaking point between Rutan and the rest of QAC.


David J. Gall

David for what it's worth the subject of pitch spring effect came up a
couple of years ago. I had complained that when the engine quit there is a
scramble to adjust the trim to hold the nose up. The trim spring made the
nose seem VERY heavy at a time when we do not need that kind of a
distraction and my plans adjuster was stiff and hard to reach with the left
hand. I was not going to let go of the stick! . I was surprised to find
that most of the guys let the trim freewheel unlocked. It is not designed
that way due to the mechanical advantage but if the bearing is made loose in
construction it would freewheel like a buzz saw. Anyhow I redesigned my trim
so it is now operated by a throttle cable control near my left hand and very
easy to disengage. It is a real pleasure to use close to the throttle, I
lock it only when stabilized in cruise, and also I lock it fully elevator up
for final approach and flare. (My throttle is done with a mixture adjuster
cable and that is also nice to use, just set and forget)

At the present time I am dealing with a related problem: Although trimmed
max elev up I need forward pressure to hold the nose down and TE up (3/16"
at 170KTS). Aeleron reflex is 3/8"up. Unless I made a mistake the CG is
same as for the Norton but the Norton line of thrust was 17mm higher. Do you
think that the thrust couple would explain the issue? I am planning to flush
the aelerons again.

Peter



_____

From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
David J. Gall
Sent: Tuesday, 17 October 2006 7:43 PM
To: Q-LIST@...
Subject: RE: [Q-LIST] Flight characteristics questions



Sam,

I think you're thinking backwards here. The described behavior indicates
sparrow strainers that are too small, not too large; or not angled enough
(trailing edge up) instead of too steeply.

Without sparrow strainers, when the airplane inadvertently goes faster than
its trimmed airspeed, the slight undercamber of the LS(1) elevator causes
aerodynamic force that pushes the trailing edge of the elevator up. This
lets the airplane's nose come down and allows the airplane to accelerate to
a yet-higher speed. NOT GOOD!

The sole purpose of sparrow strainers is to REVERSE this pattern. When the
nose inadvertently drops and the speed builds, the sparrow strainers should
push the trailing edge of the elevator down so as to raise the nose of the
airplane, thus slowing it back down. Conversely, when the airplane slows
down (due to an inadvertent climb) the decreasing dynamic pressure on the
sparrow strainers lets them allow the trailing edge of the elevators to come
up (usually in response to a down-spring in the trim system), lowering the
nose and restoring the airplane to it's original airspeed.

This is speed stability. It is closely associated with pitch stability, but
is not the same thing. Burt Rutan devoted several issues of his Canard
Pusher newsletter to describing it, discussing it, and reporting on the
requirements for it in his several homebuilders' designs.

Another clue to incorrect speed stability is light or "sensitive" pitch
control, as reported in Mr. Q2fun's item #1. True, pitch sensitivity is also
a function of CG position, but given two otherwise identical airplanes with
the same CG location, the one with greater speed stability will have
less-sensitive pitch feel. That's because the greater aerodynamic forces of
the larger or more effective (larger/correct deflection angle) sparrow
strainers will cause the elevator stick force to be greater for any given
deflection of the elevators away from their trim position. It's kind of like
using a larger paddle on a canoe, you just have to pull harder to get it to
move through the water.

A more effective sparrow strainer will also need to be met with greater
tension in the pitch down-spring of the spring-type pitch trim system at
higher airspeeds. If the down spring of the trim system is only lightly
loaded at cruise speed or if the up-spring is loaded and the down spring is
slack at cruise speed (heaven forbid!) then there is a real problem and a
potentially dangerous situation.

What happens if the up-spring is loaded at cruise? If the nose drops, the
aerodynamic forces get stronger while the spring force stays the same, so
the aerodynamic forces "win." The up-spring was resisting the aero forces
that want to make the airplane dive, but those forces now win and the
airplane dives. Conversely, if the down-spring is loaded at cruise, then a
nose drop again means larger aero forces, but those forces (from the sparrow
strainers) act to RAISE the nose, not lower it further. Raising the nose
restores the airplane to level flight.

Rutan advised his builders that his airplane designs should be
AERODYNAMICALLY trimmed to a low-cruise airspeed when flown hands-off and
with the pitch trim system disconnected. His rationale is that if a crucial
part or connection in the pitch control system should fail thereby leaving
an elevator completely disconnected from the trim system and the control
system, it does not automatically kill the pilot. I do NOT advise
disconnecting the trim system in a Q2 or Q200 or even a Quickie because of
the risks involved, but you can certainly look at your trim springs and
simulate a disconnect by moving the trim control to make them as equally
slack as possible. By this method one might be able to get a relative idea
of what the sparrow strainers are doing and what the airplane's aerodynamic
trim speed is.

In summary, I think there is a dangerous situation being described by Mr.
Q2fun and I hope he gets his sparrow strainers and trim system looked at by
one of the "old heads" on this list to see if it is rigged right or if
there's something amiss. I'll wager that the up-spring is doing a lot of
work at cruise speeds and just loses the battle against aero forces at
speeds above 150 mph. Not good -- not safe!

Just my worry-wart two cents worth,

David J. Gall
BSAE
Sacramento, CA