Quickie/Q2/Dragonfly control arrangements

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cluttonfred

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I have read various descriptions of the Quickie and its descendants calling the front wing control surfaces elevators/flaps and the rear wing surfaces ailerons.

Do we have any Quickie family builders or pilots here that can explain how those control surfaces work in practice?

Is there a separate flap lever or is the flap setting just full back stick?

Is there any pitch trim function to the rear ailerons, either manually or perhaps interconnected with the flap lever if there is one?

And why are the ailerons partial span only and inboard?

Thanks!

95261A10-1DBD-459E-BC68-0EA1D4148B84.jpeg
 

Aesquire

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Front wing surfaces are Elevators. Worked by stick. Rear wing ailerons are stick controlled, some have added a mixer to add reflex flap function for higher cruise. ( the one I worked on was early, and didn't have a mixer, I don't think it's in the original plans )

IIRC ( please correct me ) the part span ailerons were to reduce the possibility of tip stall, and simplify construction.
 

Hot Wings

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Is there any pitch trim function to the rear ailerons
That is what is commonally called the 'reflexor'. It moves the ailerons in sync for pitch trim and was not part of the original plans. There are several versions.

Control system of the Quickie. CS-13 goes to the elevator.
Stick A.jpgStick B.jpg
 

cluttonfred

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Thanks, guys, that's really helpful. If the front wing "flap" function is just full elevator and there is no need to compensate with any trimming function on the rear wing, that's good news for simplicity.

I could see going with one-piece, constant-chord wings without any twist or dihedral to keep things as simple as possible, perhaps even ultralight-style ladder-frame construction with tubes at both leading and trialing edges and separate tapered control surfaces of simple fabric over tube construction like a Sky Ranger or any number of ultralights.

 

Aesquire

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One advantage of ladder style tube construction is that building washout in is very easy. You simply build the framework, then set the wing at the appropriate dihedral & twist angles, ( I used wood blocks & a water tube level on a sloped garage floor ) and then make the cables to fit/fix the geometry.

With struts you fix the geometry with strut length.

typical aluminum 6061-t6 tubing comes in 12 foot lengths. So 24 foot plus fuselage width wingspan is the lazy guy engineering solution I've seen. ;)
 

delta

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Q2's had a habit of darting off the runway with a stiff enough cross wind because below a certain speed when landing, the combination rudder/tail wheel effectiveness wasn't sufficient. The ground angle of attack wasn't spelled out in the original plans, and the main wing would still be flying when the cannard was not. The aileron reflexor and the T-tail was designed primarily to kill that lift and give the tail wheel more grip. I'm not sure how many pilots got in trouble with having them set in the wrong position for take off, but I'll bet there were a few. I have both and I don't think I'll use either one.
I did built a belly board to control descent speed but who knows what havoc or bliss that'll bring. I don't know if anyone's tried that yet, but it should work as a "flap".
 

dwalker

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I am not sure about the Quickie, but near as I can tell both use "sparrow strainers" on the canard elevators to help balance aerodynamic load on the elevators and reduce strain and effort on the controls. The Dragonfly often uses a reflexor as a sort of gross aileron trim. What it effectively does is alter the position of the control linkage up or down, which "trims" the ailerons together. The addition of the aileron reflex control now allows you to adjust the lift that the rear lifting surface produces. The reflexor changes the ailerons into essentially flapperons and allow you to adjust the attitude of the plane in flight trimming in the fuselage to a low angle of attack. The reflexor also compensates for the different loadings because the pilot/passenger moment stations are behind the aft cg station which is somewhere over the gas tank.
Pictured is a Sparrow Strainer from one of the Dragonfly newsletters.
 

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dwalker

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Here is a humorous description of the reflexor in action-

Reflexing ( as the word is currently used in the Dragonfly world ) is the process of deflecting a portion of an airfoil's trailing edge upward to alter aerodynamic properties. For the most part, any conversation on "reflexing" will be limited to the aft wing and will mean travel of the aileron from the neutral trailing location to slightly upward (about 1/2" reflex upward). Expanding the scope of the term a bit more : when the trailing edge of an airfoil is deflected upwards or downward , a new chord line is drawn in the air. This re-defining of the "apparent AOA" will cause the airfoil to generates less or more lift and drag for the same physical Angle of Attack (AOA). This is not magic. This is exactly how ailerons work. An aileron is a reflexing surface that is under the pilots control. There just happens to be one on each side of the fuselage and they work opposite to each other. If they worked symetrically, they would be called plane flaps. So, to co-opt the ailerons to be auxiliary lift generating surfaces, we have to "reflex them up or down at the same time and at the same rate. The raising of both ailerons will make the aft wing generate less overall lift and lowering of both ailerons will make the wing generate more overall lift.

To best explain what reflexing is and what is does for the Dragonfly, we have to create an imaginary test aircraft and hire a fearless (digital) test pilot.

Poof.

Now we have a state of the art Mark II (digital) Dragonfly and test pilot.

For the sake of this discussion, our test Dragonfly aircraft has normal looking differential ailerons ( one goes up while the other goes down) that are under the pilot's control. The ailerons on a typical Dragonfly wing are inboard, 20% chord and run about 5 feet long. Some dragonfly ailerons have been outfitted with 18" long x 3" wide servo actuated tabs installed inboard to help power the ailerons up or down at higher speeds. For the purposes of this discussion, we will just pretend that the ailerons are stock and have no power assist.

Lets also say that our digital Dragonfly is equipped with with a "state of the art" ( TEAM RAPTOR BUILT ) aileron reflexor system that allows the pilot to move the ailerons differentially (as we need to do for flight control) and symmetrically ( that is both up or down together). Our fearless test pilot is instructed in there use and feeding and is looking a bit less fearless.

Now, we put our imaginary aircraft flying in flight at 3000 ft AGL, straight and level, elevators trimmed, wide open throttle at 120 mph, with the fuselage "level line" nicely "level" to the earth's gravity vector. In his fantasy Fly , our fearless pilot does expert ailerons rolls by pulling the control stick from side to side. returning to the straight and level is by the book and our pilot is looking all the better for being back into his native environment.

After some time, we get on the radio and tell the test pilot to go faster.

Even from the ground, we can see that he is perplexed. The throttle is already wide open, the gear is fixed (down) and the prop is fixed pitch. How is he going to get this bird to go faster??? At this point, the engineering team (on telecon from the Skunk Works) tell him to reduce the drag of the aircraft and it will go faster. The FCC will not allow a direct translation of what our fearless pilot replies with. Our engineers tell the pilot to tuck the elevators and reduce the aircrafts drag. That is easy enough. So the control stick goes forward (the elevators tuck up) and the houses get bigger fast. Our pilot immediately realizes that this aint going to work.

After he gets the plane back to straight and level, our our fearless pilot ask the engineers what other brilliant ideas they have. The response goes something like this: " a great deal of the aircraft's drag is being generated by the canard's elevators. Most likely they are slightly down into the breeze at this point, but even if they are trailing in neutral, they could be configured to make less drag. you have to reduce the lift demands of the canard so that the elevators can be tucked and the nose will not pitch down....."

Long about the time our fearless pilot is considering quitting this project, he remembers that there is that magic switch on the control stick that allows the ailerons to be flexed / reflexed. Nobody actually told him that reflexing the ailerons would reduce the lift requirements of the canard but he figures that it cant hurt.

He presses the aileron reflexor button and causes both ailerons to move upwards a tiny bit (as measured at their trailing edges). The aircraft goes into a gentle climb. The pilot gently pushes "forward" on the control stick ( tucking the elevators up a degree or two) and the plane goes back to flying level. Aside from re-trimming the elevators and the fuselage now flying at a degree less AOA, nothing else seems to have changed. Oh wait, yea, the airspeed is 10 mph faster than before he messed with the wings. Hummmm. Maybe these engineers are on to something. Same power, more speed. This is pilots dream. Somehow this flying machine must be making less drag now.

Well if a little is good, a lot must be even better. Our fearless pilot presses and holds the aileron reflexor button again and both ailerons to move upwards 3/4" (as measured at their trailing edges). The aircraft immediately and violently goes into a climb. The pilot slams "forward" on the control stick (tucking the elevators up many degrees) and just barely gets the plane to level out. After a few moments and some creative language, he gets the aircraft back under control and notices that he is now moving 60 mph faster than before he messed with the wings. Hummmm. What have these engineers done to him ??? Now there are very noticeable changes to the way the aircraft is flying. The re-trimming of the elevators has used up virtually all of the forward travel of the control stick. In fact, there is very little left for basic flight maneuvering. The fuselage is now flying at a several degrees less AOA than before and the thrust line is actually negative. There is something else nagging at the pilot but he cant put it into words. It is just bothering him. About the only good thing he can see is that he must be making far less drag to be going so much faster.

Back on the ground, the test conductor notices the pilot has done something to make the plane go much faster and wants to know what that is. He orders the pilot to bring the plane down without messing with any of the buttons.

The pilot pulls back on the throttle and the plane slows down for landing. As the speed drops off, the pilot becomes more and more aware that the elevators do not need to be deployed. This cant be good. In every other flight he has ever made in this tandem wing aircraft, as the speed drops off, the canard's elevators have to be deployed to make the needed lift to keep the nose up. For some reason, on this landing, the elevators are not needed to keep the nose up. In fact, as the speed bleeds off, the nose is getting alarmingly high all by itself. The pilot has no more " forward " stick control (the elevators are already fully tucked) and he is getting very excited indeed. Eventually, the fuselage is at 13 degrees and the shed wake of the canard destroys the lift of the aft wing. The tail falls out from under the plane as the aft wing's lift collapses. This is deep stall and our pilot is in deep trouble. The digital test is terminated and our fearless pilot is put back in the hanger all safe and sound.



So what happened ? ? ?



Well it is complex to say the least. The aircraft went faster as the ailerons were reflexed, but became un-controllable on landing. Though the two effects seem very different, they are both related to the same cause.

There is a lot more if you wish to read it!


Found at this link- reflexing
 

Marc Zeitlin

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Here is a humorous description of the reflexor in action.... Found at this link- reflexing
Well, all I can say to this "humorous" description is that the person who wrote it and the web page upon which it was found is incorrect - see:


While there is some accuracy to the description of what's going on in general terms of behavior, the theory that the center of lift of the airfoils (and therefore the airplane as a whole) moves as one deflects the ailerons and/or elevators is basically incorrect. The reason reflexers work is that they allow the incidence angle of the FUSELAGE to be optimized in cruise flight for lowest drag, and they also allow the forward wing/elevator to be operated in the drag bucket for the airfoil. Unlike Mr. Stick, however, I don't have the time or energy to fully elaborate, humorously or not.
 

dwalker

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Well, all I can say to this "humorous" description is that the person who wrote it and the web page upon which it was found is incorrect - see:


While there is some accuracy to the description of what's going on in general terms of behavior, the theory that the center of lift of the airfoils (and therefore the airplane as a whole) moves as one deflects the ailerons and/or elevators is basically incorrect. The reason reflexers work is that they allow the incidence angle of the FUSELAGE to be optimized in cruise flight for lowest drag, and they also allow the forward wing/elevator to be operated in the drag bucket for the airfoil. Unlike Mr. Stick, however, I don't have the time or energy to fully elaborate, humorously or not.
I have to be honest, I have read and re-read bits of that page and some of it I can follow pretty well and other bits confound me. Not unusual for me really, so thanks for the input!
 

cluttonfred

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Interesting to me at least, that same explanation is part of the rationale for the Gatard Statoplan designs which function in pitch much like the system described for the Quickie despite a relatively conventional appearance. In the Statoplan, however, the rear wing (it is a lifting surface though small) is interconnected with the stick for trim only. The result is a plane that does change fuselage angle with varying speeds, but only a little bit, just four degrees from maximum to minimum speed.

gatard.jpg

The reason reflexers work is that they allow the incidence angle of the FUSELAGE to be optimized in cruise flight for lowest drag, and they also allow the forward wing/elevator to be operated in the drag bucket for the airfoil. Unlike Mr. Stick, however, I don't have the time or energy to fully elaborate, humorously or not.
 

Rik-

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Merely from researching and attempting to purchase a few Q200's here's what I've learned.

The "Refluxor" can be thought of (from someone who learned to fly in an RV) as a Flaperon. Plane and Simply that's what it is doing to your ailerons. You can fancy your definition up with all kinds of mumbo jumbo but at the end of the day it's a simple design to loose lift evenly across both ailerons at the same time.

Ground handling, please refer to this video of an actual builder/flyer Mike Dwyer.

Ground handling, from conversations with actual pilots, seems to be good if the builder/rigger or what ever title you want to call the person, had the for site to place both front tires in a parallel and square configuration as some builders, innocently or ?, built the canard with one tire several inches aft of the opposite one, hence not square to one another.

Also, what I have gathered is that the braking system itself can be as good or as bad as the builder/rigger or what ever title you want to call the person installed or changed to. These planes came with recommendations for a set of brakes that were small, yet effective and yet with to much foot pressure could put the plane on it's nose. Changing to a stronger design sounds good but sometimes if the combination is off with the misalignment (corrective action for this was recognized and labeled as the "Gall Wheel Alignment") of the tires could result in a darty plane when the brakes were applied. But even with this cure, a deepish mud puddle on the runway could cause the plane to hook around or what was more common was the pilot would edge one tire off the runway and the extra drag of the gravel/dirt/rock/grass would pull the plane around on the pilot rather quickly if the pilot was not paying attention.

Contributing to this instability was also the fact that the original plans called for a hand brake that offered no differential braking between the two wheels, which was further changed to two hand brakes controlling one per wheel which was finally brought into the modern world with the installation of a conventional foot brake system.

Lastly contributing to the ground handling was the deign oversite, aka incorrect tail wheel geometry installation. With the installation of more caster the plane decided to track better and thus after the first few flying examples show'd what was not desired in means to ground handling, changes were made to the tailwheel for ground stability (obviously) but also to beef up the tail wheel mount as the pole design extending through the tail was prone to break off when the pilot was not kind to the air to ground interaction.

There were 6 basic fundamental changes made to the Q200's to tame or improve them know as the Jim Bob 6 Pack. Named after Bob Farnum N200QK and Jim Ham.

Gall Wheel Alignment
Differential Brakes/Toe Brakes installation
Refluxor installation
Air Brake Belly Board installation
Tail Wheel Geometry change
Rudder to tail wheel separation (the original plans had the tail wheel use a drag link to move the rudder, a hard landing could remove the tail wheel and thus the rudder control)
La Rue Brake Design.

These made the Q2 and the Q200's a lot more docile plane when on the ground.
 
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