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From everything I can gather, canards offer significant gains in performance characteristics, and most the drawbacks apply only if you remove the tail. Why not mix them together? What does Piaggio know that we don't?

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  • $\begingroup$ With all the effort over the years to go with flying wings so there is only one surface, going for 3 is kinda going the wrong way doncha think? Canards have historically been a flop, because of the compromises that come with the potential performance gain. The Piaggio's speed largely comes from its laminar flow fuselage profile, not so much from having 3 surfaces. $\endgroup$ – John K Aug 31 at 1:40
  • $\begingroup$ I hadn't heard anything of such efforts. Were there any proposed GE flying wings? Are they a significant improvement over today's wing-and-tail design? Thay look like they will be a pain to get usable space out of. What compromises come from having 3 surfaces? $\endgroup$ – Jason Summer Aug 31 at 2:39
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    $\begingroup$ In theory, the fewer surfaces the better, but flying wings have their own limitations, mainly a tendency toward twitchy pitch behaviour, and a very narrow center of gravity range, being so short coupled. The single wing with a tail surface is nearly universal because it just meets the balance of compromises the best. $\endgroup$ – John K Aug 31 at 2:53
  • $\begingroup$ It's almost a flying wing, just chopped up and placed where it's needed most :P My main contender is the Katmai, which is enhanced by the canard addition (which demonstrates another advantage, retrofitting rather than overhauling) $\endgroup$ – Jason Summer Aug 31 at 3:09
  • $\begingroup$ The original motive for a flying wing was to make the fuselage a useful lifting surface rather than a simple parasite, really nothing to do with reducing the number of surfaces. The low radar signal was discovered as a side benefit and so efforts moved in optimizing that aspect. 3 surface aircraft are mechanically redundant in the wrong ways, and really they just lack a market. $\endgroup$ – Max Power Sep 2 at 11:41
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Canards are not used in general aviation simply because they have complexe interaction with the main wing which can leeds to issues with stability and being at the front of the CG their effect on flight dynamics may be highly unintuitive in some situations. Therefore you need electronic control to adapt the pilot input to the control surface in order for the plane to fly as expected, and that's why in my opinion it was not suited to GA where electronic was expensive until the past few years. But they are plenty of jet fighter using them as they have the ability to greatly increase performance and maneuvrability.

In addition 3 surface aircraft means more wetted aera thus more drag, complex design and control, more mechanical moving parts which will often drive the price up.

You can find more information looking at the patent issued in 1988 by Piaggio here : https://worldwide.espacenet.com/publicationDetails/description?CC=US&NR=4746081A&KC=A&FT=D&ND=&date=19880524&DB=&locale=en_EP

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  • $\begingroup$ Just ask the MiG design bureau pilots who liked the MiG-8 Utka extremely well because of its easy flight handling. That was well before the time of electronic stability augmentation. Done right, a canard is a pleasure to handle. Only its performance will be poor. $\endgroup$ – Peter Kämpf Sep 21 at 8:59
  • $\begingroup$ I have seen static canards stapled onto existing aircraft, like the katmai, so I don't see how it would have to add more moving parts. You can also decrease drag because you no longer need tail down force $\endgroup$ – Jason Summer Sep 22 at 16:39
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canards offer significant gains in performance characteristics

That is news to me. So far, I have viewed the canard wing as akin to an extended spoiler which messes up the flow over the main wing.

The benefit of a canard wing on the Avanti is to shift the main wing back so the main spar does not run through the cabin. Note that the canard does not have flaps, so it avoids some of the drawbacks of canard wings. Also, its span is small and its free vortices hit the engine gondolas, so they have no chance to mess up the spanwise angle of attack distribution over the wing (as most other canards do).

For pitch control and for trimming the airplane with flaps down, the Avanti has a regular T-tail, so the canard's task really is restricted to shifting the wing back. This is a clever design but its use is restricted to small business airplanes with straight wings. Airliners and most swept wing airplanes in general would not benefit from the small backward shift a similar canard wing could offer, so their conventional layout has merits. In most GA aircraft, the spar runs below the pilot seat and can well be integrated with the general layout, so again an added canard wing would not improve the design.

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    $\begingroup$ "Restricted to small planes with straight wings". Or presumably with forward-swept wings $\endgroup$ – MSalters Sep 22 at 15:05
  • $\begingroup$ @MSalters: Right, but even more exotic. The HFB-320 Hansa Jet comes to mind. Sweep was generous enough to not even require that additional canard wing. $\endgroup$ – Peter Kämpf Sep 22 at 15:57
  • $\begingroup$ The reason I think there's a gain to be had is potentially eliminating tail down force, and while I was researching it, found an aviator quoted as saying "I fly a canard equipped Cessna 182 and it improves all aspects of the performance envelope". So my suggestion of performance gains is partially theoretical, partially tested and approved $\endgroup$ – Jason Summer Sep 22 at 16:48
  • $\begingroup$ @JasonSummer: These canards help for short take-offs but hardly improve cruise fuel flow or top speed. This quote is from someone who has something to sell. $\endgroup$ – Peter Kämpf Sep 22 at 16:52
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The first aeroplane ever to fly under its own power, the Wright Flyer, was a canard design. Once they better understood the issues of stability and control, the Wrights experimented with a three-surface arrangement before abandoning the foreplane altogether after the French pattern. Admittedly nobody yet quite knew what they were doing, but the Wrights' abandonment is symptomatic of the problems the canard surface faces.

As has been pointed out, the Piaggio Avanti adopted a foreplane primarily to shift the main spar aft. Another solution to that problem is to sweep the main wing forward, as was done on the HFB Hansajet. Both types are/were medium-size bizjets with the same problem - how to max the cabin size when a main spar keeps getting in the way. Forward sweep has been adopted by sailplanes on occasion for much the same reason, but a three-surface design would impair the airflow over the main wing.

Another successful three-surface family comprises the several variants and derivatives of the Sukhoi Su-27 jet fighter which added a canard, such as the Su-30 and Su-33, but here the goal is supermanoeuvrability.

I am less jaundiced over canards than some who have posted answers here - some designs have been outstandingly successful, although the last one in general aviation that I can recall off hand was the pioneer-era ASL Valkyrie. But I would say that they are a lot harder to get right than a tail, and only worth pursuing in exceptional circumstances - whether you keep the tail or not.

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