New canard designs?

[rotax618]

Many pure deltas had conical wingtips, I assume ”Splates” are wing tip end plates. Larry Heuberger was an aeronautical engineer who was responsible for the design of the first Lear Jet.
My opinion is that there isn’t any advantage to Canards - they require more runway, less climb performance, place the prop where it is easily eroded and damaged by FOD from the UC, and because of the higher loading and low RN of the canard can have variable trim because of dirt and rain etc. the Herberger and RMT Batalier aircraft fixes most of those problems by placing the prop high or above the wing, and making the wing behave more like a pure delta with a canard “trim” surface rather than a tandem wing.

 

[rtfm]

Duncan, a couple more quick thoughts...some of your other designs have featured a large door rather than a canopy.

I have?

...that tiny canard give me the heebie-jeebies as it would have very little authority and very limited CG range to keep the front:rear wing loading ratio to about 3:2. Here is the Piel Onyx for comparison:

View attachment 113842

You're serious? Have you heard of Burt Rutan's designs?

This is where X-Plane comes in. It is frowned upon here on the forum as a serious aircraft design tool, but I disagree. It is capable of modelling existing aircraft extremely well, and also of modelling new designs. I plan to put the new DMC-01 through its paces to check on precisely this sort of thing. And once I have a working model, I'll build a RC model and give it a fly.

 

[rtfm]

And just for fun, here is the Latécoère 225, a prototype canard amphibian ultralight that looks like someone found a kit for a conventional pod and boom design without the instructions and put it together backwards. ;-)

Ha ha. Where do you find these things?

 

[rtfm]

Any thoughts on the proposed Western Red Cedar strip plank construction method? I gave my local marine timber stockist a call yesterday to verify the 2.1kg/m^2 claim, and they say it's true. "Yes, just on 2kg per square metre".

I'll cut the formers out of cheap 12mm ply, and the permanent bulkheads out of Gaboon ply.

 

[rtfm]

I made a blunder in the workshop yesterday - I made two left hand side fins (the fin is in two halves glued together). And now I've run out of wood. So while I wait for both the wood and the wing hinges to arrive, I'm sitting here at the computer thinking about the DMC-01.

Any thoughts about linking the pivoting canard to the flap lever?

One of the reasons an all-flying canard is a bad idea is that an all-flying wing stalls at a much higher AoA than a flapped one. And a canard which resists stalling is not a great idea. HOWEVER, if I link the pivot to the flap lever, there is no chance of this happening. Or is there? X-Plane - where are you when I need you?

 

[cluttonfred]

If you rig an all-flying canard like a Mignet front wing, I don't see why an all-flying canard would be a problem. You need the hinge point a little forward of the most forward CP location before the stall angle of attack and a reflexed airfoil (or ground-adustable trim tab) to allow hands-off cruise. On your comment on stall angles, remember that the AOA line of a wing goes from the leading edge to the trailing edge, so lowering the flap *is* raising the AOA even if the front of the wing doesn't move relative to the fuselage.

 

[rtfm]

Nothing's easy, is it? But when I think of it there's a whole lot of similarity between a canard plane and a Flea. Both cannot allow the rear wing to stall and both have the front wing more heavily loaded. The major difference is that in a Flea, the front wing does most of the heavy lifting, while with a canard equipped plane, the rear wing does this.

But if I understand you correctly, treating the fore wing of a canard plane like the front wing of a Flea as far as control is concerned is an interesting concept.

Mmmm

 

[poormansairforce]

Any thoughts on the proposed Western Red Cedar strip plank construction method? I gave my local marine timber stockist a call yesterday to verify the 2.1kg/m^2 claim, and they say it's true. "Yes, just on 2kg per square metre".

I'll cut the formers out of cheap 12mm ply, and the permanent bulkheads out of Gaboon ply.

I love it! Very light, strong, and a lesser grade wood could be used. And less expensive ply to be purchase.

 

[rtfm]

I've had a bunch of "bright ideas" which turned out to be complete failures. Let's hope this isn't one of them...

 

[rtfm]

Hey, cluttonfred,
Just pursuing a thought here. Since a canard plane is (in many respects) a reverse-Flea, what about pivoting the rear wing? I have no idea if this is sensible or just plain silly, but thought experiments cost nothing.

I'm off to the shops (we're in lockdown here, so I get to go out once a day only). I'll pursue this idea when I get back.

Regards,
Duncan

 

[Riggerrob]

And just for fun, here is the Latécoère 225, a prototype canard amphibian ultralight that looks like someone found a kit for a conventional pod and boom design without the instructions and put it together backwards. ;-)

View attachment 113843
View attachment 113844

We wonder how well that short hull planes????
What is the beam to length ratio?
How stable is it in pitch, on the water?
What is the maximum wave height?

 

[rtfm]

Back from the shops-outing, replete with mask and hand-sanitiser...

OK, what about this? What if one pivoted both wings to the flap lever? Much increased lift at take-off and flare, but "normal" canard flight for the rest of the time. The canard wing would operate with its elevator as normal, and the rear wing would be locked at 3 degrees or so. Pivoting the main wing would produce a lot of forward pitching moment, and the canard might not be able to cope. So we have two options: (1) increase the size of the canard (2) use a very low pitching moment airfoil on the main wing.

Question:
Why do canard planes use the Eppler 1212 (or similar) airfoils on the rear wing? Why not something with a very low pitching moment, like the 23112, or the 747A315? The latter is laminar to 40% of the top surface, and 70% on the bottom surface. Max CL isn't that great though. Stalls roughly where the Roncz canard airfoil stalls, but since the canard wing is set to a differential of 3 or 4 degrees, there's little chance of the rear wing stalling first.

 

[rotax618]

If you have sufficient chord and a low pitch moment on the rear wing you don’t need a canard.

 

[Voidhawk9]

Any thoughts about linking the pivoting canard to the flap lever?

You'll already use up all available CL with the elevator / flap. Pivoting the canard will simply increase it's AoA further past the stall - nothing 'free' to be had here.

Pivoting BOTH surfaces would be similar to but much heavier and more complex than just pitching the aircraft up, no?

 

[WBNH]

You could scale down something like the "Lockspeiser LDA-01 Experimental Utility Transport"

+



=

Oshkoshavan...


A liveaboard that's not a seaplane...

 

[cluttonfred]

Strip planking could be very interesting though you'd have to run the numbers on strength and weight to be sure it makes sense. A 3 m x 1 m x 1 m box seems like a good approximation of two-seat canard fuselage, cutting out 1 m2 for cockpit access and miscellaneous openings, that still leaves 13 m2 of surface area so 27.3 kg for the basic fuselage shell without longerons, seats, controls, gear, engine mount, etc.

Duncan, you wrote that "the main spar in both a rectangular wing plan and a swept wing pass through the fuselage in the same place." How do you figure that? If the wing is placed relative to the center of gravity, then the main spar moves forward at the root relative to the center of gravity in order to maintain the same relationship with the aerodynamic center.

If you pivot the rear wing on a Pou-du-Ciel you've created a short-coupled conventional aircraft with a big, all-moving stabilator. That can certainly work and you do gain some of the low-speed benefits of a tandem but without the stall resistance of a canard or Pou-du-Ciel. You've essentially made a Lacroix Autoplan.

 

[rtfm]

...I'm just going round in circles at the moment. I've spend seven straight hours at the keyboard. Time for a walk. Maybe tomorrow this will all make more sense to me.

 

[Bigshu]

I am surprised that there are almost no new canard designs out there competing in the LSA/light experimental/European microlight markets. Since the vast majority of designs out there are very conventional low-wing or high-wing designs, a canard would really stand out and attract those looking for something different.

I know of the French Junqua IBIS, a wood-and-fabric design, but I have seen few completed on my trips to Europe. I also know of a few one-off projects, but nothing else for which kits or plans are available.

Does anyone know of any newer canard designs, especially on the light end of the spectrum?

Cheers,

Matthew

That link doesn't go to an aircraft related page, it's some women's design group...I'm familiar with the Ibis though.

 

[Sockmonkey]

Hmmm...what are "splates"?

Split plates maybe?

...I'm just going round in circles at the moment. I've spend seven straight hours at the keyboard. Time for a walk. Maybe tomorrow this will all make more sense to me.

Welcome to me head. I regularly go round and round trying to find that one new magic configuration.

 

[rtfm]

Duncan, you wrote that "the main spar in both a rectangular wing plan and a swept wing pass through the fuselage in the same place." How do you figure that?

As usual, I was mistaken. Sigh...

If you pivot the rear wing on a Pou-du-Ciel you've created a short-coupled conventional aircraft with a big, all-moving stabilator.

Or a Pulga.

Yesterday wasn't my best. 7 hours at the keyboard, and I started thinking in circles.

My wood still hasn't arrived, nor has the wing folding hardware, so what to do? Well, today I took my explorations into Canards, my thoughts about placing the front wing below the rear, and married these to the Flea and to strip planking. Here's today's output.



Fuselage length: 2860mm
Front wing span: 6675mm
Rear wing span: 5560mm
Cockpit width: 700mm (27 inches)
Engine: 50hp
Anticipated empty weight: 120kg

Plenty of wing separation both vertically and horisontally.

Cheers,
Duncan