New canard designs?

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cluttonfred

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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
 

Hot Wings

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I am surprised that there are almost no new canard designs out there competing in the LSA/light experimental/European microlight markets.
I'm not surprised, at least for US LSA aircraft. A canard comes to the market with a huge disadvantage, other than the safety aspect of the canard stall.

Because a canard will have a higher stall speed for a given wing area an LSA canard will either have to use more Hp to get to the maximum legal cruise speed or fly slower on the same Hp, compared to a conventional plane. That isn't something the marketing department wants to try to sell.
 

cluttonfred

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I'm not surprised, at least for US LSA aircraft. A canard comes to the market with a huge disadvantage, other than the safety aspect of the canard stall.

Because a canard will have a higher stall speed for a given wing area an LSA canard will either have to use more Hp to get to the maximum legal cruise speed or fly slower on the same Hp, compared to a conventional plane. That isn't something the marketing department wants to try to sell.
In a category of aircraft in which the maximum level speed is regulated and designers often have to choose engines or props to limit the maximum speed, I am not sure that's a disadvantage.
 

KeithO

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Meeting the stall speed requirement seems to be tough enough even for people like Vans and that is using a conventional flapped wing that they take all the way to stall. The need for the canard to be angle of attack limited, compared to the main wing, means that all forms of high lift devices on the main wing are out, due to the complication of trying to apply high lift devices simultaneously in a balanced fashion on 2 different lifting surfaces.

While a canard could be built to meet the requirement, would it be viable ? If the span required is 35 ft vs 26.75, that is going to take a lot of material to build. How would you like the view out front if you needed such a long span canard ? How do you think it would perform in a crosswind with the canard low in front to try to improve forward vision ?

Generally, most canards have been built "hot". They have tiny wings and canards for going really fast and economical cruise. A pusher configuration is commonly used to avoid the complication of the prop wash influencing the lift characteristics of the Canard. But as reality shows, the pusher configuration together with the relatively fragile landing gear and high landing speeds makes walking away from off airport pavement an unlikely affair.

Rutan was king of the canard design and he has basically withdrawn from this configuration. The new work he does is all conventional.
 

cluttonfred

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KeithO and Hot Wings, thanks for your comments, but I think you might be a little over the top in damning the entire canard configuration outright. Not all current LSAs and microlights use high devices, in fact many of the lighter designs get by with no flaps at all for simplicity's sake. I also believe that stall/spin resistance, visibility and "wow factor" would all have more appeal than you seem to think. I agree that high wing loading, high stall speed canards like the VariEze and LongEze are not what's needed, but I don't agree that a canard microlight is out of the question. Hugh Lorimer is a member of this group, and his prototype Iolaire was a serious attempt at a canard that would fit British BCARS microlight rules. I think you can see in the layout of his design had the potential to answer some of the crashworthiness issues as well by using the long nose as a crumple zone. Cheers, Matthew
 

Autodidact

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Canards are sooo 1970's! :D:speechles

Seriously, though, a higher stall speed per unit of wing area means more wing area is required to get the stall speed down and thus more empty weight. Not much, perhaps, but in a weight restricted class, this does reduce the usefull load.

I think that the tandem wing concept in your avatar is a better candidate for LSA.
 

cluttonfred

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Uh oh, watch out, for the tandem option we'll surely have to start another thread, wind me up and I'll keep going and going and... ;-)

Just to confuse matters, here are the Landray GL3 Pouss Pou (in English via Google Translate) and Briffaud GB-10 Pou Push (in English via Google Translate), both Mignet-type tandem wing designs but with pusher engines with a result much like a canard. Both flew successfully, the Landray model as a light two-seater, though only ballast was carried where the second seat would go.


 

Autodidact

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Those are both very interesting - strange, it seems sort of obvious, but I don't think I would ever have thought to make a Flea a pusher!
 

Kristoffon

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I too was a fan of canards until I read their section in Daniel Raymer's Aircraft Design book and understood the trade-offs. Off the top of my head, the stability and CG travel requirements make the canard a lower efficiency wing plus the canard's downwash over the main wing nullifies any advantage the design might have had over conventional. There are some great canard designs out there but once you compare the numbers they aren't faster than similar conventional craft by much (if at all).
 

TFF

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Pous have a problem. You can not let the front wing go negative attack; the plane will go into an unrecoverable dive if it does. Very easy to fly but you have to float down you cant push the nose over. Most have limit stops, so pretty much you have up only.
 

cluttonfred

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TFF, first off, the unrecoverable dive was an issue resolved over 70 years ago and it is silly to keep repeating that as if it is always out there ready to bite you.

On the handling issue you raise, well, other than a gentle dive to maintain airspeed in a power off approach, I can't say that I have ever, or ever plan to, dive my aircraft Stuka-style.

I have flown an HM-1000 Balerit briefly (here's a pic of one) and did not notice any issues in pitch, except that the aircraft was pleasantly responsive in pitch but damped right out when you stopped moving the control wheel.



In short, maybe you ought to give it a try before repeating the very old critiques of the Mignet planform which, if true, would not leave hundreds of Mignet-type aircraft still flying today and new ones being completed all the time. Here's a nice video of a modern Pou du Ciel in action.

 
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cluttonfred

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Those are both very interesting - strange, it seems sort of obvious, but I don't think I would ever have thought to make a Flea a pusher!
We're getting off topic here, but the mark against a pusher Flea is the need to keep the CG far enough forward to keep the wing loading on the front wing substantially higher than on the rear wing. That is critical for good flight characteristics, just like in a canard, but with the larger wing forward the CG needs to be even further forward than in a canard.

That is why both of the pusher Mignet types above have wings of almost equal area and why the Balerit uses the neat trick of a hollow prop hub turning on the rear fuselage boom to keep the weight of the engine well forward but still have pusher visibility.
 

KeithO

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So the question I have is what kind of flying qualities were actually achieved. There is no info listed regarding the performance of any of the designs. I see the British ultralight class requires a 35kt stall speed, thus harder to achieve than our LSA requirement. The all flying Canard I am sure is beneficial but that can get a bit critical at higher airspeeds for flutter. I'm not sure how that was addressed and there does not appear to be any mass damping going on.

While Hugh used extruded polystyrene in the fuselage and cabin, I presume based on cost and ease of carving, this could be substituted with a better core material for better long term life expectancy. Delamination of extruded polystyrene is pretty common, since it is used in the RV industry in the US and typically doesn't last much more than 10 years if you are lucky and that is on fairly low loaded parts like seats and table tops.

I will take the numbers from the PDF and plug it into airplane PDQ to see what is predicted...

but I don't agree that a canard microlight is out of the question. Hugh Lorimer is a member of this group, and his prototype Iolaire was a serious attempt at a canard that would fit British BCARS microlight rules.
 

TFF

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The the design flaws are known and kept in check if done right, but about every 10 years someone has to test it, to prove why they should have listened.
 

Autodidact

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I have read many things about the flea. As I understand it, the original flea's wings overlapped - the trailing edge of the front wing extended longitudinally back past the leading edge of the rear wing so that when trying to pull out of a steep dive, the "gap" between the two wings was closed up and they then both began to act as a single wing with a "slot" and as a consequence, pitch control was lost.

The fix was simple, and discovered very quickly: the fuselage was stretched so that the gap between the wings no longer would close up. This fix was engineered in the 1930's and there has not been a problem since, as far as I know. I have heard of no problems with the Flea in the modern era. A weight shift trike will "tumble", but that is not a Flea.

The popularity of Flea type aircraft in Europe seems to indicate that there is now no unusual problem with the aerodynamics of this design.
 

Hot Wings

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t I think you might be a little over the top in damning the entire canard configuration outright.

Me denigrate canards? No way! In fact I am building based on some of the very reasons you mentioned, like visibility and crash protection. But I also know that I'm giving up some performance at both ends of the envelope to a conventional arrangement.

When you start talking LSA's that are typically costing $50K+ the customers which can actually afford the plane start looking real hard at the spec sheets of their options. If $50K is pocket money for your target group then you can market on emotion.

As another poster mentioned, the tandem wing approach may be a better option since one can use flaps to a limited extent. Keep in mind that there are several "flavors" of tandem wing and often the line between canard and tandem is quite fuzzy.

Another forgotten plane to look at for some of the same benefits given by a canard is the Durand Mk5.
 

cluttonfred

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As this seems to be moving in the direction of a design discussion on tandem wings, I'm going to start a new thread over in design area. Cheers, Matthew
 

Durand Sky Ranch

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Hello,

New here but I own a Durand Mk 5. I love it and it is very hard to stall. Also one advantage to the forward lower wing is it has kind of a built in flare regarding groud effect.

Thanks!
 
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