Reflexor, Elevator and takeoff/landing angle


Jay Scheevel
 

You all remember the QAC description of a typical non-eventful takeoff in the conventional Q2 lifting off from 3-point and rising into the air like an elevator. If the plane is built properly with the 3 wheel deck angle appropriately set up for the plane, this take off is the norm. The reason that this is possible is because there are two, roughly equal sized flying surfaces, each lifting is appropriate load cradling the load between them. If CG or decalage or ground angle differ from the perfect mix, the reflexor and/or airspeed/elevator combination will allow this 3 point takeoff to occur with some care.

 

So the question is: If the taildragger can lift off at a constant angle and rise like an elevator, why can’t the tricycle gear do the same?

 

The taildragger lifts off with roughly 7 degrees deck angle, so the conventional thinking is that the tri-gear needs to also rotate to this same angle to take off, right? 

 

Using my calibrated aero model, I started creating some initial settings charts for my airplane (Tri-gear, decalage of -1.5 degree---meaning wing leading edge down 1.5 degree relative to plans built). The chart below shows the settings indicated to take off (fly level in full ground effect) for my plane at 1000 pounds GW, loaded to the most forward CG at 42”. 

 

I am forced to answer to my question above as follows: I apparently CAN take off from 3 point stance in my tri-gear by setting the reflexor trailing edge DOWN instead of TE UP. My loaded taxi angle is about 4 degrees nose up. Based on the chart below, I can take off from 3 point (4 degrees deck angle) at 75 mph CAS with reflexor set TE down 2 degrees, while holding 12 degrees of TE down elevator deflection.

 

Of course the same chart also shows that if my Q2 was a taildragger having a taxi deck-angle of  6.5 degrees could take off at 70 mph with the reflexor set to 6 degrees TE UP, and holding 17 degrees of TE down elevator deflection.

 

After I thought about this, I remembered something Phil Lankford said about his tri-q a while back relating to landing with reflexor. Phil said the following:

 

“I like to use aileron TE down for approach till touch down. This assures a good visibility of the approach and maximum main wing lift.  It is easily overcome with elevator control while near touch down and once I’m on all three wheels I dump to reflexor TE up. “

 

I think that his landing description is validation of the same point I am making, namely a three point, touchdown  (full ground effect) as a opposed a three point takeoff in a tri-gear Q2.

 

Any comments on my latest heresy?

 

Cheers,

Jay Scheevel, Tri-Q2, built and building taxi time.

 

 


Jim Patillo
 

Phil’s airplane was built by Bob Malacek. It was a taildragger, not a Tri-Q👌 but you knew that.

Jim
N46JP-Q200


Jay Scheevel
 

I thought that Phil had a more recent replacement for the no longer existent Malecek ship, and that version was a tri-gear, but I guess I am mistaken.

Sent from my Verizon Wireless 4G LTE DROID


"logistics_engineering@... [Q-LIST]" <Q-LIST@...> wrote:

 

Phil’s airplane was built by Bob Malacek. It was a taildragger, not a Tri-Q👌 but you knew that.

Jim
N46JP-Q200


David J. Gall
 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Gary McKirdy
 

Hi Jay, 
You will probably find in practice that you use full down elevator briefly to rotate before checking forward as soon as the nose starts to rise.
Aft C of G or reflexor causing ailerons trailing edge up will allow earlier rotation but with the need to quickly stop it as you dont want to look or feel like you are entering  a loop just after liftoff.
The more nose heavy or nose down reflexor the higher the speed and the greater the airframe stored energy to get further round the loop but at least you have a bit more time to correctly check climb out angle  it with stick forward.
Be prepared for both until you find the sweetspot. Eitger way you likely use full aft elevator to rotate. Question is for how long...
This relates to Q2 tri gear only.
Regards
Gary McKirdy


On Thu, 21 Jun 2018 23:00 'Jay Scheevel SGT' jay@... [Q-LIST], <Q-LIST@...> wrote:
 

You all remember the QAC description of a typical non-eventful takeoff in the conventional Q2 lifting off from 3-point and rising into the air like an elevator. If the plane is built properly with the 3 wheel deck angle appropriately set up for the plane, this take off is the norm. The reason that this is possible is because there are two, roughly equal sized flying surfaces, each lifting is appropriate load cradling the load between them. If CG or decalage or ground angle differ from the perfect mix, the reflexor and/or airspeed/elevator combination will allow this 3 point takeoff to occur with some care.

 

So the question is: If the taildragger can lift off at a constant angle and rise like an elevator, why can’t the tricycle gear do the same?

 

The taildragger lifts off with roughly 7 degrees deck angle, so the conventional thinking is that the tri-gear needs to also rotate to this same angle to take off, right? 

 

Using my calibrated aero model, I started creating some initial settings charts for my airplane (Tri-gear, decalage of -1.5 degree---meaning wing leading edge down 1.5 degree relative to plans built). The chart below shows the settings indicated to take off (fly level in full ground effect) for my plane at 1000 pounds GW, loaded to the most forward CG at 42”. 

 

I am forced to answer to my question above as follows: I apparently CAN take off from 3 point stance in my tri-gear by setting the reflexor trailing edge DOWN instead of TE UP. My loaded taxi angle is about 4 degrees nose up. Based on the chart below, I can take off from 3 point (4 degrees deck angle) at 75 mph CAS with reflexor set TE down 2 degrees, while holding 12 degrees of TE down elevator deflection.

 

Of course the same chart also shows that if my Q2 was a taildragger having a taxi deck-angle of  6.5 degrees could take off at 70 mph with the reflexor set to 6 degrees TE UP, and holding 17 degrees of TE down elevator deflection.

 

After I thought about this, I remembered something Phil Lankford said about his tri-q a while back relating to landing with reflexor. Phil said the following:

 

“I like to use aileron TE down for approach till touch down. This assures a good visibility of the approach and maximum main wing lift.  It is easily overcome with elevator control while near touch down and once I’m on all three wheels I dump to reflexor TE up. “

 

I think that his landing description is validation of the same point I am making, namely a three point, touchdown  (full ground effect) as a opposed a three point takeoff in a tri-gear Q2.

 

Any comments on my latest heresy?

 

Cheers,

Jay Scheevel, Tri-Q2, built and building taxi time.

 

 


Gary McKirdy
 

As for landing. Dont try to 3 point it. Fully held off maingear first or risk breaking nose leg as each porpoise will get bigger applying heavier loads to nose leg until it breaks probably on number 3. That happens quick if you still have energy reserve in the airframe on a short coupled Q. Lose as much of that energy BEFORE mains touch.
Hope that help ye all over the pond and elsewhere...
Gary McKirdy

On Fri, 22 Jun 2018 18:02 Gary McKirdy, <gary.mckirdy21@...> wrote:
Hi Jay, 
You will probably find in practice that you use full down elevator briefly to rotate before checking forward as soon as the nose starts to rise.
Aft C of G or reflexor causing ailerons trailing edge up will allow earlier rotation but with the need to quickly stop it as you dont want to look or feel like you are entering  a loop just after liftoff.
The more nose heavy or nose down reflexor the higher the speed and the greater the airframe stored energy to get further round the loop but at least you have a bit more time to correctly check climb out angle  it with stick forward.
Be prepared for both until you find the sweetspot. Eitger way you likely use full aft elevator to rotate. Question is for how long...
This relates to Q2 tri gear only.
Regards
Gary McKirdy


On Thu, 21 Jun 2018 23:00 'Jay Scheevel SGT' jay@... [Q-LIST], <Q-LIST@...> wrote:
 

You all remember the QAC description of a typical non-eventful takeoff in the conventional Q2 lifting off from 3-point and rising into the air like an elevator. If the plane is built properly with the 3 wheel deck angle appropriately set up for the plane, this take off is the norm. The reason that this is possible is because there are two, roughly equal sized flying surfaces, each lifting is appropriate load cradling the load between them. If CG or decalage or ground angle differ from the perfect mix, the reflexor and/or airspeed/elevator combination will allow this 3 point takeoff to occur with some care.

 

So the question is: If the taildragger can lift off at a constant angle and rise like an elevator, why can’t the tricycle gear do the same?

 

The taildragger lifts off with roughly 7 degrees deck angle, so the conventional thinking is that the tri-gear needs to also rotate to this same angle to take off, right? 

 

Using my calibrated aero model, I started creating some initial settings charts for my airplane (Tri-gear, decalage of -1.5 degree---meaning wing leading edge down 1.5 degree relative to plans built). The chart below shows the settings indicated to take off (fly level in full ground effect) for my plane at 1000 pounds GW, loaded to the most forward CG at 42”. 

 

I am forced to answer to my question above as follows: I apparently CAN take off from 3 point stance in my tri-gear by setting the reflexor trailing edge DOWN instead of TE UP. My loaded taxi angle is about 4 degrees nose up. Based on the chart below, I can take off from 3 point (4 degrees deck angle) at 75 mph CAS with reflexor set TE down 2 degrees, while holding 12 degrees of TE down elevator deflection.

 

Of course the same chart also shows that if my Q2 was a taildragger having a taxi deck-angle of  6.5 degrees could take off at 70 mph with the reflexor set to 6 degrees TE UP, and holding 17 degrees of TE down elevator deflection.

 

After I thought about this, I remembered something Phil Lankford said about his tri-q a while back relating to landing with reflexor. Phil said the following:

 

“I like to use aileron TE down for approach till touch down. This assures a good visibility of the approach and maximum main wing lift.  It is easily overcome with elevator control while near touch down and once I’m on all three wheels I dump to reflexor TE up. “

 

I think that his landing description is validation of the same point I am making, namely a three point, touchdown  (full ground effect) as a opposed a three point takeoff in a tri-gear Q2.

 

Any comments on my latest heresy?

 

Cheers,

Jay Scheevel, Tri-Q2, built and building taxi time.

 

 


Jay Scheevel
 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord). Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@...
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jay Scheevel
 

Thanks Gary,

 

Your experience and willingness to share it is appreciated. I anticipate the situation you describe (arresting pitch increase as soon as gear leaves the ground), so I have been practicing that, even in my sleep. The encouraging  component of the modeling indicates that the faster the airplane at takeoff, the less aggressive forward correction required. I anticipate that I will be forward of mid-CG and will dial in neutral reflexor, when I do my first flight. This seems to give the most options. I will have 10000 feet of runway so will try not to jerk it off too early or too aggressively.

 

Cheers,

Jay

From: Q-LIST@...
Sent: Friday, June 22, 2018 11:02 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Reflexor, Elevator and takeoff/landing angle

 

 

Hi Jay, 

You will probably find in practice that you use full down elevator briefly to rotate before checking forward as soon as the nose starts to rise.

Aft C of G or reflexor causing ailerons trailing edge up will allow earlier rotation but with the need to quickly stop it as you dont want to look or feel like you are entering  a loop just after liftoff.

The more nose heavy or nose down reflexor the higher the speed and the greater the airframe stored energy to get further round the loop but at least you have a bit more time to correctly check climb out angle  it with stick forward.

Be prepared for both until you find the sweetspot. Eitger way you likely use full aft elevator to rotate.. Question is for how long...

This relates to Q2 tri gear only.

Regards

Gary McKirdy

 

 

On Thu, 21 Jun 2018 23:00 'Jay Scheevel SGT' jay@... [Q-LIST], <Q-LIST@...> wrote:

 

You all remember the QAC description of a typical non-eventful takeoff in the conventional Q2 lifting off from 3-point and rising into the air like an elevator. If the plane is built properly with the 3 wheel deck angle appropriately set up for the plane, this take off is the norm. The reason that this is possible is because there are two, roughly equal sized flying surfaces, each lifting is appropriate load cradling the load between them. If CG or decalage or ground angle differ from the perfect mix, the reflexor and/or airspeed/elevator combination will allow this 3 point takeoff to occur with some care.

 

So the question is: If the taildragger can lift off at a constant angle and rise like an elevator, why can’t the tricycle gear do the same?

 

The taildragger lifts off with roughly 7 degrees deck angle, so the conventional thinking is that the tri-gear needs to also rotate to this same angle to take off, right? 

 

Using my calibrated aero model, I started creating some initial settings charts for my airplane (Tri-gear, decalage of -1.5 degree---meaning wing leading edge down 1.5 degree relative to plans built). The chart below shows the settings indicated to take off (fly level in full ground effect) for my plane at 1000 pounds GW, loaded to the most forward CG at 42”. 

 

I am forced to answer to my question above as follows: I apparently CAN take off from 3 point stance in my tri-gear by setting the reflexor trailing edge DOWN instead of TE UP. My loaded taxi angle is about 4 degrees nose up. Based on the chart below, I can take off from 3 point (4 degrees deck angle) at 75 mph CAS with reflexor set TE down 2 degrees, while holding 12 degrees of TE down elevator deflection.

 

Of course the same chart also shows that if my Q2 was a taildragger having a taxi deck-angle of  6.5 degrees could take off at 70 mph with the reflexor set to 6 degrees TE UP, and holding 17 degrees of TE down elevator deflection.

 

After I thought about this, I remembered something Phil Lankford said about his tri-q a while back relating to landing with reflexor. Phil said the following:

 

“I like to use aileron TE down for approach till touch down. This assures a good visibility of the approach and maximum main wing lift.  It is easily overcome with elevator control while near touch down and once I’m on all three wheels I dump to reflexor TE up. “

 

I think that his landing description is validation of the same point I am making, namely a three point, touchdown  (full ground effect) as a opposed a three point takeoff in a tri-gear Q2.

 

Any comments on my latest heresy?

 

Cheers,

Jay Scheevel, Tri-Q2, built and building taxi time.

 

 


Jay Scheevel
 

Thanks for your perspective, Gary. My discussion was mostly focused on takeoff, but your caution on landing is a good one. Bouncing the nose gear punches the aircraft to higher AOA increasing the bouncing tendency as you point out until something breaks. Attempting to three point a taildragger and mistakenly striking the tailwheel first however, decreases the angle, and dampens things a bit if you are not too slow.  Your advice to lose the energy with higher AOA drag is a good point too. I have built my cabin about 2” higher, so my view over the nose is better than most. I anticipate that I will transition to landing with reflexor TE up over time as I gain insight.

 

From: Q-LIST@...
Sent: Friday, June 22, 2018 11:07 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Reflexor, Elevator and takeoff/landing angle

 

 

As for landing. Dont try to 3 point it. Fully held off maingear first or risk breaking nose leg as each porpoise will get bigger applying heavier loads to nose leg until it breaks probably on number 3. That happens quick if you still have energy reserve in the airframe on a short coupled Q. Lose as much of that energy BEFORE mains touch.

Hope that help ye all over the pond and elsewhere...

Gary McKirdy

 

On Fri, 22 Jun 2018 18:02 Gary McKirdy, <gary.mckirdy21@...> wrote:

Hi Jay, 

You will probably find in practice that you use full down elevator briefly to rotate before checking forward as soon as the nose starts to rise.

Aft C of G or reflexor causing ailerons trailing edge up will allow earlier rotation but with the need to quickly stop it as you dont want to look or feel like you are entering  a loop just after liftoff.

The more nose heavy or nose down reflexor the higher the speed and the greater the airframe stored energy to get further round the loop but at least you have a bit more time to correctly check climb out angle  it with stick forward.

Be prepared for both until you find the sweetspot. Eitger way you likely use full aft elevator to rotate. Question is for how long...

This relates to Q2 tri gear only.

Regards

Gary McKirdy

 

 

On Thu, 21 Jun 2018 23:00 'Jay Scheevel SGT' jay@... [Q-LIST], <Q-LIST@...> wrote:

 

You all remember the QAC description of a typical non-eventful takeoff in the conventional Q2 lifting off from 3-point and rising into the air like an elevator. If the plane is built properly with the 3 wheel deck angle appropriately set up for the plane, this take off is the norm. The reason that this is possible is because there are two, roughly equal sized flying surfaces, each lifting is appropriate load cradling the load between them. If CG or decalage or ground angle differ from the perfect mix, the reflexor and/or airspeed/elevator combination will allow this 3 point takeoff to occur with some care.

 

So the question is: If the taildragger can lift off at a constant angle and rise like an elevator, why can’t the tricycle gear do the same?

 

The taildragger lifts off with roughly 7 degrees deck angle, so the conventional thinking is that the tri-gear needs to also rotate to this same angle to take off, right? 

 

Using my calibrated aero model, I started creating some initial settings charts for my airplane (Tri-gear, decalage of -1.5 degree---meaning wing leading edge down 1.5 degree relative to plans built). The chart below shows the settings indicated to take off (fly level in full ground effect) for my plane at 1000 pounds GW, loaded to the most forward CG at 42”. 

 

I am forced to answer to my question above as follows: I apparently CAN take off from 3 point stance in my tri-gear by setting the reflexor trailing edge DOWN instead of TE UP. My loaded taxi angle is about 4 degrees nose up. Based on the chart below, I can take off from 3 point (4 degrees deck angle) at 75 mph CAS with reflexor set TE down 2 degrees, while holding 12 degrees of TE down elevator deflection.

 

Of course the same chart also shows that if my Q2 was a taildragger having a taxi deck-angle of  6.5 degrees could take off at 70 mph with the reflexor set to 6 degrees TE UP, and holding 17 degrees of TE down elevator deflection.

 

After I thought about this, I remembered something Phil Lankford said about his tri-q a while back relating to landing with reflexor. Phil said the following:

 

“I like to use aileron TE down for approach till touch down. This assures a good visibility of the approach and maximum main wing lift.  It is easily overcome with elevator control while near touch down and once I’m on all three wheels I dump to reflexor TE up. “

 

I think that his landing description is validation of the same point I am making, namely a three point, touchdown  (full ground effect) as a opposed a three point takeoff in a tri-gear Q2.

 

Any comments on my latest heresy?

 

Cheers,

Jay Scheevel, Tri-Q2, built and building taxi time.

 

 


Jerry Marstall <jnmarstall@...>
 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J

-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 3:34 PM (GMT-05:00)
To: Q-LIST@...
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jay Scheevel
 

Your ability to boil things down to their essence is a asset, Jerry.  Keep ‘er pointed forward.

 

Cheers,

Jay

 

From: Q-LIST@...
Sent: Friday, June 22, 2018 1:48 PM
To: Q-LIST@...
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J

 

-------- Original message --------

From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>

Date: 6/22/18 3:34 PM (GMT-05:00)

Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jerry Marstall <jnmarstall@...>
 

Hadn't thought of that last statement.

-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 4:01 PM (GMT-05:00)
To: Q-LIST@...
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Your ability to boil things down to their essence is a asset, Jerry.  Keep ‘er pointed forward.

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Friday, June 22, 2018 1:48 PM
To: Q-LIST@...
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J

 

-------- Original message --------

From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>

Date: 6/22/18 3:34 PM (GMT-05:00)

Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Paul Fisher
 

Thanks Jerry, I thought it was just me!  Push up the power and manipulate the stick as necessary!

Paul


On Fri, Jun 22, 2018, 14:48 Jerry Marstall jnmarstall@... [Q-LIST] <Q-LIST@...> wrote:
 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J


-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 3:34 PM (GMT-05:00)
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jerry Marstall <jnmarstall@...>
 

Ah, another great idea

-------- Original message --------
From: "Paul Fisher rv7a.n18pf@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 4:06 PM (GMT-05:00)
To: Q-LIST@...
Subject: Re: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Thanks Jerry, I thought it was just me!  Push up the power and manipulate the stick as necessary!

Paul

On Fri, Jun 22, 2018, 14:48 Jerry Marstall jnmarstall@... [Q-LIST] <Q-LIST@...> wrote:
 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J


-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 3:34 PM (GMT-05:00)
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jay Scheevel
 

Wise elders!

 

 

From: Q-LIST@... Sent: Friday, June 22, 2018 2:21 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Ah, another great idea

 

-------- Original message --------

From: "Paul Fisher rv7a.n18pf@... [Q-LIST]" <Q-LIST@...>

Date: 6/22/18 4:06 PM (GMT-05:00)

Subject: Re: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Thanks Jerry, I thought it was just me!  Push up the power and manipulate the stick as necessary!

 

Paul

On Fri, Jun 22, 2018, 14:48 Jerry Marstall jnmarstall@... [Q-LIST] <Q-LIST@...> wrote:

 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J

 

-------- Original message --------

From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>

Date: 6/22/18 3:34 PM (GMT-05:00)

Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Sam Hoskins
 

Of course Jerry would say:

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J

He was an F-4 fighter pilot. Never forget that, I don't. 

Sam

Sent via wireless Gizmo.


On Fri, Jun 22, 2018, 2:48 PM Jerry Marstall jnmarstall@... [Q-LIST] <Q-LIST@...> wrote:
 

I bet I am the only guy out their that doesn't understand a word of this.. I just get in, push up the power and go.   So far, so good. J


-------- Original message --------
From: "'Jay Scheevel SGT' jay@... [Q-LIST]" <Q-LIST@...>
Date: 6/22/18 3:34 PM (GMT-05:00)
Subject: RE: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

Hi David,

 

Your comments are always appreciated. The moments are incorporated in the modeling, so yes they do contribute, however all other things being equal, I can understand why you see the incompatibility. I can summarize the issue as follows. Control surface deflection (downward) increases the camber of the airfoil, thereby increasing the lift, but also increases forward pitching moment. Rotating the aircraft to a higher AOA increases the lift but GREATLY increases the forward pitching moment of the each airfoil. The magnitude of moment increase resulting from the AOA is more significant than the magnitude moment increase from higher camber, so the 4 degree AOA scenario accounts for overall lower forward pitching moment at the moment of flight. The numbers for my modeled wings are as follows (moments are relative to 25% chord).. Forward pitching sign-convention is negative.

 

For the case of 6.5 degree AOA takeoff with 17 degrees of down elevator, and 6 degrees of TE UP reflexor:

                              Cl             Cm

Canard              1.72       -0.165

Main Wing       0.46        -0.801

 

For the case of 4 degree AOA takeoff with 12 degrees of down elevator, and 2 degrees of TE DOWN reflexor

                              Cl             Cm

Canard              1.47       -0.113

Main Wing       0.45        -0.697

 

By normalizing each scenario’s Cm’s by a factor that makes total Cl=1.0 (for purposes of comparison), the 6.5 degree AOA scenario’s forward pitching moment  is 105% that of the 4.0 degree AOA scenario’s pitching moment

 

Cheers,

Jay

 

From: Q-LIST@... <Q-LIST@...>
Sent: Thursday, June 21, 2018 11:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 

Jay, something doesn’t add up. At constant gross weight and CG location, you cite liftoff at two different combinations of elevator and reflexor deflection that seem incompatible to me. In one, your reflexor is 2deg TE down and your elevator is 12deg down; in the other, your reflexor is 6deg TE up and your elevator is 17deg down. It seems to me that one or the other of these conditions will result in a rapid pitch change (rotation about the lateral axis) and will be unsustainable immediately after liftoff. Are you including airfoil pitching moments in your calculations? They are required for determining pitch equilibrium.


Jim Patillo
 

Jay,

I concur with Jerry and Paul. You are way over thinking this. If your plane was built right, you should be able to hold the stick in neutral position, run up to lift off speed, pull back slightly and be airborn? That’s how it works on mine. Real simple.

Disqualifer! I only know about Q tail dragger characteristics, not TriQ.

As you know, the reflexor was a band aid for an ill fitting canard or main wing and using this device is very powerful. Having had all these years taking measurements to get it right, I would have thought you would have designed that sort of stuff out of your plane. Btw,My cg is 41-47.5”. And I do not use evevator or reflexor for take off. Everything stays neutral.

I do reflex up after landing to keep pressure on the tail wheel.

Jim
N46JP Q200


Jim Patillo
 

Jay,

I appreciate your offline comments and your continuing desire to cross every “T” and dot every “I”.

Just know this plane is more forgiving than you think, unless you get it to far out of line!

Relax, take a deep breath and things will be fine.

Have you set a date to turn that hangar queen into a real flying Q?

Jim
N46JP Q200
Weekly Q driver.


Jay Scheevel
 

Thanks Jim,

 

No date set yet. Have one “T” to cross and one “I” to dot. The “T” is getting comfortable with the cockpit layout/sight picture while taxiing up to about 50 mph at my home field (then will take the plane to the longer Grand Junction runway).  The “I” is to go fly with a few folks (if they agree to do so), probably Bruce Crain and Lynn French. Once I get that done, I will come back home, get in and go.  Will keep you posted.

 

Cheers,

Jay

 

From: Q-LIST@...
Sent: Friday, June 22, 2018 5:35 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Re: Reflexor, Elevator and takeoff/landing angle

 

 


Jay,

I appreciate your offline comments and your continuing desire to cross every “T” and dot every “I”.

Just know this plane is more forgiving than you think, unless you get it to far out of line!

Relax, take a deep breath and things will be fine.

Have you set a date to turn that hangar queen into a real flying Q?

Jim
N46JP Q200
Weekly Q driver.


David J. Gall
 

Jay,

Pitching moment does not increase with angle of attack. Please review NACA Report No. 824 or Theory of Wing Sections. You’ll find that the coefficient of moment is nearly constant across all non-stalled angles of attack.

The equilibrium equations can be found in any standard text on stability and control or flight mechanics, such as Perkins & Hage or Nelson.