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Len Evansic

XPlane canard models vs. reality

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I can't contain myself.

 

I'm so anxious to build and fly a canard I bought XPlane to simulate the actual physics of flying. So I've searched for and found XPlane models for Long EZ, Vari-EZ, and Cozy Mk. IV's on the web, but I think there are either serious bugs in them, the program itself, or my ability to fly this type of plane.

 

First I tried out the Cozy model. It was made for the 6.x version of XPlane, and I'm running version 7.61. I thought XPlane was throwing some serious weather and turbulence at me because the plane would jump up and down all over the place in flight. When I made the panel transparent, I saw that the elevators were fluttering chaotically. I botched a landing, and tried again, but the plane was jumping around while parked on the runway! Something's not right...

 

Next-up the Long-EZ. This seemed to handle much better, but it also seemed to be almost untrimmable for level flight. No matter how straight and level I had the plane, it would constantly turn or pitch and not maintain a heading. Aleron, rudder, and elevator trim could not remove either of these tendencies.

 

Frustrated, I thought that maybe my installation of XPlane was suspect, so I loaded up a Cesna 172. This model was rock solid. Very trimmable, and nothing erratic. Extremely easy to fly and control.

 

So, after this, I got to thinking. Since XPlane uses an aerodynamic model of the plane to govern the simulation, is the canard type of plane an inherently difficult to control beast? Am I just lacking the proper finesse, or are these models I downloaded just screwed up? I'm new to flying and have never had the privilege of flying in a canard plane, so any insight would be greatly appreciated.

 

-- Len


-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

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I So, after this, I got to thinking. Since XPlane uses an aerodynamic model of the plane to govern the simulation, is the canard type of plane an inherently difficult to control beast?

Not at all. I gave a ride to a guy yesterday (Sunday) who had never flown anything other than MS Flight Simulator. He was able to control the plane for 15 minutes, no problem, without my touching the stick or even giving him much in the way of instruction other than "go there", "don't hit that", and "get back up to 3000 ft.".

 

Am I just lacking the proper finesse, or are these models I downloaded just screwed up?

No, and I suppose, yes. I'd go back to the source of your models and find out what versions of X-plane they're compatible with.

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Len, what are you using to control flight with? Anything but a joystick will surely be difficult. I'm just about ready to upgrade, but am wondering whether to go with a left- or right-handed version (big decision). Just for kicks I attached a pick of Curt Boyll's VariEze model (of www.vigilanceaero.com) and a Cozy Mark IV as it transforms into a lawn dart (I had to release controls in order to jump out of the plane to take the picture :)).

 

Posted Image

 

Posted Image

 

I can assure you that the feeling of flying a canard for real is incredibly easy and fluid. I was with Marc when he gave a check-out ride to Steve Brooks, and Steve was beside himself over how well Marc's Cozy flew and handled in the air. He just couldn't get over it.

post-386-141090152808_thumb.jpg

post-386-141090152814_thumb.jpg


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Long-term:  Building a Cozy Mark IV

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This is an interim Cozy Mk IV for X-Plane version 7.61. It has only a standard X-Plane instrument panel, not a custom photo-panel, but it is equipped for IFR. The focus of this model is primarily accuracy in handling and performance, as opposed to being completely seamless eye-candy. I am still working on this one and the LongEZ; the pitch-buck is not exactly correct for the Cozy right now, for example. I intend to get photos of actual aircraft in order to produce the eventual panels for these. This Cozy flight model for X-Plane is a stable, smooth-flying airplane which requires very little trim. Includes a visible belly-board speedbrake, and transparent canopy.

 

http://www.vigilanceaero.com/CozyMk4_761.zip

 

Sorry about the delay in producing my new LongEZ and Cozy for X-Plane. I have been working in my hangar a lot, setting up a heated work area so that I can get back to work on my real Cozy Mk IV, N272CZ (reserved).

 

Curt Boyll

Longmont 2V2 Colorado VariEze N111JK and building Cozy Mk IV N272CZ (res.)

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Len, what are you using to control flight with? Anything but a joystick will surely be difficult. I'm just about ready to upgrade, but am wondering whether to go with a left- or right-handed version (big decision).

I'm using a Saitek Cyborg Evo joystick. It's nice, but I think it isn't stable enough in the neutral position for X-Plane. When I do the calibration thing, the neutral position appears to be biased towards the left end of the bar (non-linear or non-centered) for pitch, yaw and rudder. As I mentioned before, I tried to trim these biases out, but it doesn't seem to work.

 

A fresh install and a new download of my existing model (O-320 powered with Infinity retracts) is waiting for me at home to distract me from the election coverage.

 

-- Len


-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

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This is an interim Cozy Mk IV for X-Plane version 7.61. It has only a standard X-Plane instrument panel, not a custom photo-panel, but it is equipped for IFR. The focus of this model is primarily accuracy in handling and performance, as opposed to being completely seamless eye-candy.

Thanks Curt! I'll try it out tonight!

 

-- Len


-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

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For those interested in other aircraft designs for X-Plane, or if you clicked on my company link provided by Jon and saw only some stuff about a helicopter FTD, you can find several other X-Plane designs from this page also at my site:

 

http://www.vigilanceaero.com/airplanes.html

 

The free download pages have not been updated recently, but here is a list of images of most of the projects I've done since 1999:

 

http://www.vigilanceaero.com/survey.html

 

Some of these are not linked, and some designs available are not shown (like the latest SpaceShipOne and White Knight). Post here or send me a message if there is interest in one which is not downloadable from that list of images. I'm known as the guy who does Burt Rutan/Scaled Composites designs for X-Plane.

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Hi,

 

We tried it yesterday. One Finnish Cozy owner warned that Cozy

is very hard fly and land and that I could not land it to even

the biggest airfields in Finland.

Either the X-plane model is very inaccurate or his claims are wrong since

we successfully landed the virtual Cozy yesterday just with first try.

I had set wind to 8 knots and added some turbulence, but no

problem. In fact the airplanes I am currently flying, require a lot

more attention in the landing or otherwise the nose gear will

fail. Because I have never tried a simulator that would be completely

realistic so far, I am a bit sceptical, it just can't be that easy

in real life I guess or is there some unset realism settings in the

X-plane (hopefully it is not in a sort of arcade mode or something,

perhaps someone can assist me if he/she has better knowledge how

to put all realism on in X-plane if there is a such setting).

 

Best Wishes,

Karoliina

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We tried it yesterday. One Finnish Cozy owner warned that Cozy is very hard fly and land and that I could not land it to even the biggest airfields in Finland.

That is an absurd claim. I fly my COZY MKIV into 3000 ft. runways that are 40 ft. wide with a 15 Kt. crosswind all the time, and have 500-1000 ft. to spare, both on takeoff and landing. It's hard to believe that all runways in Finland are shorter than 2000 ft. and narrower than 40 ft. - it would be very difficult to get scheduled airline flights into fields that small.

 

Either that guy was pulling your leg (joking with you), or he's a terrible pilot.

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Either the X-plane model is very inaccurate or his claims are wrong since we successfully landed the virtual Cozy yesterday just with first try.

Wow, you're a much better virtual pilot than I am. The model that Curt provided the other day worked better for me, but I kept over-correcting when trying to land. I think I need a bit more practice.

 

Still, I noticed some behavior that didn't match what is claimed on some web pages. John Slade claims that his Cozy lifts off of the ground at 70 mph, while both Cozy models I tried in X-plane needed at least 100 Kts. before lifting off. I'm still trying to hit max speed in either model, without going into a dive to do it. Also, the air-brake doesn't seem to provide enough drag or slope increase for hitting a normal aproach. I think the models are nice, but not accurate enough yet.

 

I guess what the sim lacks most is real seat-of-the-pants feel. Like almost everybody else, I can't afford a snazzy hydraulic simulator platform, so I'll just have to do the next best thing and build one of these for real. :D

 

-- Len


-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

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Thanks for feedback comments on the prototype Cozy for X-Plane. It is not finished yet, not by a long shot, but it is better than any other Cozy for X-Plane that I have tried. I have the benefit of flying an actual VariEze, which is similar to a Cozy. But I have not flown an actual Cozy yet.

 

One aspect of these planes is that they are quite sensitive. Pilot induced oscillations and overcontrolling are common problems for transitioning pilots and novices. One recommendation in the real airplane is to use just your fingertips -not your whole hand- on the control stick. A corollary recommendation for flying the simulator version is to arrange an armrest for your stick arm. The real plane has armrests, your arm is well supported in the real airplane, and when I started using a chair with armrests, my flying in the sim became more realistic compared with the real airplane.

 

And as to whether the aircraft are easy to fly or not, as I said I fly a VariEze- the most difficult example among VariEze/LongEZ/Cozy aircraft. I believe my Cozy for X-Plane is easier to fly than my VariEze for X-Plane, and this apparently matches reality.

 

I was advised that I would probably need to do 2 or 3 aborted approaches in my real-life VariEze before I could actually make my first landing in it. This was not so- I landed the real airplane just fine on my first attempt. (maybe 100 landings in the sim had something to do with this ... ? :) )

 

Concerning rotation speed on takeoff, the adjustments for refining this in X-Plane are related to the refinement of pitch buck (stall) behavior. These are still being developed for this Cozy prototype. The speed at which you can lift the nosewheel/canard is somewhat influenced by your runway elevation and the ambient temperature (but not as much as actually lifting the mains off the runway). But check your ambient temp and airport elevation. X-Plane is rather accurate in modifying performance due to high Density Altitude.

 

Otherwise, the behavior I'm trying to get is the standard "VariEze speeds are about 10 higher than LongEZ/Cozy speeds" dogma. Therefore based on published specs for the Cozy, and on how my VariEze flies, we should ultimately see the following for the Cozy Mk IV (but not yet in the current example):

 

Vr to lift the nosewheel/canard: 52 KIAS

Liftoff speed clear of the runway: 75 KIAS

Pitch buck stall in level flight: 62 KIAS

Downwind Pattern speed: 90 KIAS

Base Leg Pattern speed: 80 KIAS

Final Approach speed: 70 KIAS

 

It's great to see Mark Z. posting here, and hopefully any critique of these speeds for the Cozy will be provided shortly.

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It is not finished yet, not by a long shot, but it is better than any other Cozy for X-Plane that I have tried.

I flew it around last night quite a bit and was very impressed with how much better it flew, even over your VariEze model.

 

Please keep up the great work when you have time. We'll wait patiently for improvements as you move along. Thank you for a great model!

 

BTW, are you building a Cozy?

post-386-14109015282_thumb.jpg

post-386-141090152826_thumb.jpg


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Long-term:  Building a Cozy Mark IV

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That is an absurd claim. I fly my COZY MKIV into 3000 ft. runways that are 40 ft. wide with a 15 Kt. crosswind all the time, and have 500-1000 ft. to spare, both on takeoff and landing. It's hard to believe that all runways in Finland are shorter than 2000 ft. and narrower than 40 ft. - it would be very difficult to get scheduled airline flights into fields that small.

There is no scheduled airline traffic to those airfields.

Those where the airliners land, are of course bigger, usually

kilometers long (1 km = 1000 m ~ 3000 feet).

However, to fly around the country, I would like to land

to airfields that have no air traffic control and that are narrow and

short, just to visit nice places around. Still, in general they are longer

than 2000 feets and wider than just 40 feet except some exceptions

where it is not possible to land with a Cozy anyway (grass fields

and such).

 

That guy just believes that Cozy is very hard to fly and requires

lots of experience of high power aircraft.

But he is just that kind of guy, not only was

the question about flying, but the other things too.

He have also been trying to discourage me from starting the project,

he is pretty convinced that I just can't do it and I will waste

my life, health, money, time and whatever if I start.

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Hi,

 

I by the way experimented with the X-plane model yesterday.

If the weight would remain the same, but the motor would

give 260 hp instead of 180, it would be a great aerobatics

plane. At least the model can do many kind of tricks and didn't

indicate any problem.

 

I also tried to get it to deep stall, but it just didn't go. I moved

the cg as much back as possible, but still it did not deep stall.

Finally I got it to a sort of backwards spin where I got out by

putting the motor to full power (I had modified the model to 350 hp,

so it appeared to be powerful enough to do it, I tried it also with

105 hp and it wouldn't have been enough to get it out).

I will try to modify the aircraft

in the editor since I would like to demystify what is the deep

stall on the first place. How about removing the lower winglets

in addition to moving the cg? Perhaps adding some overweight

and a underpowered engine?

 

Actually X-plane is pretty fun to try to find out what happens

if the builder does something wrong in the building process, assuming

that it is accurate at least to some extent.

 

Best Wishes,

Karoliina

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Yup, my wife and I are building Cozy Mk IV plans # 872. We started in 1999, and have had to take 2 different year-long breaks from it. The new heated facility that I have built in our hangar will help us get back to building. Flying the VariEze (N111JK) is very useful regarding the Cozy. We are much more knowlegeable about what we will want in the new plane. We will have hundreds if not thousands of hours in the VEZ before we test fly the Cozy. And the VEZ is so severely limited in useful load, flying in it together REALLY makes us want to finish the Cozy (or to buy another VEZ !). Again, thanks for the feedback on the new Cozy model for X-Plane. I'm also working on a Defiant for a fellow in Venezuela. The best real-life example that I have ever seen is currently in a hangar not far from my own here on Vance Brand airport. Not sure if Defiant for X-Plane will be offered for free download. But the LongEZ and Cozy should be done soon.

 

Curt Boyll - flying VariEze N111JK and building Cozy Mk IV #872 (N272CZ res.) Boulder/Longmont 2V2 Colorado

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Regarding a Cozy with more horsepower, Karoliina, one way to do that and not have too much weight aft is to consider the Rolls-Royce/Allison 250 turboshaft engine. This is what the fellow from Venezuela is considering for the Defiant he wants to build. The Allison 250-B17F weighs about the same as the Lycoming O-320, but it produces 420 HP. The only problem would be severely limited range due to fuel capacity and the 250's thirst.

 

I'm not surprised that you were unable to get the Cozy for X-Plane to deep stall. If you are modifying the CG location simply in the flight simulator (not with PlaneMaker) then you cannot move it beyond the design limit. And because it was carefully designed both in real-life (by Nat Puffer) and in X-Plane by me, it will not deep stall because a deep stall is undesireable (to say it politely).

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Vr to lift the nosewheel/canard: 52 KIAS

 

It's great to see Mark Z. posting here, and hopefully any critique of these speeds for the Cozy will be provided shortly.

The rest of the speeds are pretty close, but as you should have noticed from the long discussions on the mailing list, this one is WAY too slow. 52 Kt is about 60 mph, and I don't know ANY COZY that can lift the nose at 52 Kt (plus there's no reason to do so, since you can't fly under approximately 60 - 70 Kt (depending upon weight and CG) anyway.

 

I rotate at about 80 - 85 mph (70 - 74 Kt), and many folks rotate 10 - 15 Kt. higher than that.

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If I recall correctly, I got that 52 kt number from a LongEZ driver, and that is also a number from my VariEze. Thanks for the correction. My tech advisor is amazed at how slow my VariEze can be going and still get the nose up or hold it up. When I land, I can keep the nose up down to about 40 mph, if I have the nerve. But this is in an O-235-powered VariEze- lots of weight back there that wasn't intended by the designer. I've added 45 lbs of ballast in the nose- 25 around the battery and another 20 under my seat. This gets me to the rear of the first-flight restricted CG box, not quite to the middle of the CG range. And the plane still handles like it's slightly tail-heavy. It's correct, recently weighed on platform scales. But once that O-235 starts moving up or down, it wants to keep moving.

 

I'll correct the speeds for the Cozy, do some more tweaking and testing of the rotation speed and pitch-buck behavior, and try to get the updated design uploaded some time this weekend.

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Curt, thank you once again for another great addition to the community! :)


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Long-term:  Building a Cozy Mark IV

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And here is the Cozy Mk IV for X-Plane v7.62:

 

http://www.vigilanceaero.com/Cozyposter.jpg

 

http://www.vigilanceaero.com/CozyMkIV.zip

 

This one carries the tail number that we have reserved for the Cozy that we are building, N272CZ. Still trying different ideas for the panel and the paint, just like many at our stage of building. And it is the sweetest-flying one of the whole bunch. That figures- the Cozy is the most-well-developed one in reality, too. (The trim color is Copper, not orange ... seems appropriate.)

 

Oh, also- here's a Defiant with O-360's:

 

http://www.vigilanceaero.com/Defiantposter.jpg

 

http://www.vigilanceaero.com/Defiant.zip

 

A Freebie ... oh wait, they're all freebies ... :)

 

 

P.S.- if you downloaded the LongEZ, here is an improved version (engine gauges):

http://www.vigilanceaero.com/LongEZ.zip

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On one of the x-plane Cozy's I downloaded, the rudders appeared to swing both ways past neutral. I thought the Cozy's rudders only moved outward, not inward. Did anyone else notice?

 

J.

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Um, Strider,

 

:confused: Hmmm.

 

OK, so I thought the Cozy and Long-EZ used a modified Eppler 1230 for the main wing airfoil, and a Roncz 1145 (or is it 1045) for the canard. When I look into your model's airfoil folder, I see Eppler 804 and Roncz 904 foils. Are these mis-named or approximates for the real ones?

 

I have an older XPlane Cozy model by someone else (with retracts) that uses an Eppler 1230 and a modified GU 25, similar to the original Long-EZ. Just wondering what the difference is.

 

-- Len


-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

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( ... it's not enough that the dog talks ..?) Oh, sorry nothing. Regarding the rudders and the airfoils, I sure am glad folks are flying and enjoying the airplanes for X-Plane that I have posted. But yes indeed, there are limitations to what the computer software can do, no matter how many years one has spent bending and breaking its rules to get a design to handle and perform closer to reality.

 

X-Plane is a virtual wind tunnel, not a look-up-table re-creation-by-rote of an airplane's behaviour. As such, it is doing a whole bunch of calculations that some experts still insist cannot be done in real-time on affordable computer equipment. This enforces certain limitations.

 

The distinctive one-way rudders of Rutan designs, the upward motion of SpaceShipOne's Tailbooms, and more accurate adherence to definitive data describing airfoils will one day be added to X-Plane. The developer (a single individual) works VERY hard at advancing the program on a daily basis.

 

Currently, even if the program was extremely accurate in the application of airfoil polars, these are not available for the Roncz airfoils, much less the MODIFIED Eppler airfoil. Even if I had the money, the data simply is not available at any price. The airfoils in my designs are carefully designed and modified to support accurate aircraft handling and performance. The numbers accompanying the airfoils, for example Eppler 804, are an indication that I established this version in August, 2004. I do not have and never will have the correct Eppler or Roncz data. These cannot be derived from the airfoil shape- it must be the actual airfoil performance data from wind tunnel testing (polars of Cl, Cd, and Cm). Airfoils available for X-Plane and purported to be the correct Eppler and Roncz for Rutan simply are not.

 

Thank you very much for your interest, and I hope the X-Plane designs benefit you as much as they have me, ultimately making me safer and more competent in my real-life Rutan homebuilt. Greater accuracy is always my focus in more than 8 years designing in X-Plane, and these most recent examples (VariEze, LongEZ, Cozy, Defiant, Proteus, Symmetry, White Knight, and SpaceShipOne) for X-Plane will be updated as often as possible.

 

Post here if you have not found D/L links for free X-Plane designs of all of the airplanes in the list above.

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Thank you very much for your interest, and I hope the X-Plane designs benefit you as much as they have me, ultimately making me safer and more competent in my real-life Rutan homebuilt.

I love what you have done, thanks for all of your contributions. Thanks again for describing what X-Plane is doing, and their attempt to improve it.

 

From a guy who has yet to even figure out how to do a pattern,

 

J.

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