TFF
Well-Known Member
You really need two to adjust. That is something I would not want to do manually.
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The primary reason for designing 3- surfaces revolves around the cabin. The Piaggio Avanti may have 3-surfaces, but it trims like a conventional airplane. The primary reason that it was 3-surfaces is balance. Designers wanted to route the main wing's spar aft of the rear cabin pressure bulkhead. Since this placed the center of lift too far aft, they added a small lifting surface to the nose. So the canard works like another part of the main wing, albeit displaced by a few feet.
Another alternative is the forward-swept wing on the Hansa Business Jet. Again, this routes the Hansa Jet's main spar aft of the rear cabin pressure bulkhead, but it created a structural problem which required a heavier wing structure to prevent divergence.
Similarly, the Eagle light trainer uses 3-surfaces to avoid placing the main wing directly above or directly below the cockpit. This improved visibility from the Eagle's cockpit. Unfortunately, Eagle did not go "whole hog" by installing a side door(s) to ease access to the cockpit.
Another alternative is the forward-swept wing on the Hansa Business Jet. Again, this routes the Hansa Jet's main spar aft of the rear cabin pressure bulkhead, but it created a structural problem which required a heavier wing structure to prevent divergence.
Similarly, the Eagle light trainer uses 3-surfaces to avoid placing the main wing directly above or directly below the cockpit. This improved visibility from the Eagle's cockpit. Unfortunately, Eagle did not go "whole hog" by installing a side door(s) to ease access to the cockpit.
I always thought that the three surface airplane config was so that you could use high very lift devices on the wing, have another "balance" flying surface with high lift devices to deal with all that main wing hi-lift pitching moment, and then have a lightly loaded control surface in the back.
For example, the Cessna 100 series and its huge flaps creates a situation where you can easily run out of elevator authority on landing. The tail is plenty big enough to push down with only 20 degrees of flap and/or mid-range CG... but when you go to 40 degrees of flap at a forward CG, you're not able to keep the nose off the ground on flare/landing. So people have to carry extra engine power, to put enough air on the elevator, to force the tail down.
So Peterson mounted a nice size canard on the engine mount, with its own control surface. This canard lifts the nose from the front, instead of overloading the tail at the back, leaving the tail with plenty of reserve power to flare and/or maneuver.
For example, the Cessna 100 series and its huge flaps creates a situation where you can easily run out of elevator authority on landing. The tail is plenty big enough to push down with only 20 degrees of flap and/or mid-range CG... but when you go to 40 degrees of flap at a forward CG, you're not able to keep the nose off the ground on flare/landing. So people have to carry extra engine power, to put enough air on the elevator, to force the tail down.
So Peterson mounted a nice size canard on the engine mount, with its own control surface. This canard lifts the nose from the front, instead of overloading the tail at the back, leaving the tail with plenty of reserve power to flare and/or maneuver.
Making your passenger sit in the rear seat makes it land real nice
Yes I know, but having my wife sit behind me, holding a 12 inch length of safety wire in her hands, presents an entirely different type of primary control issue...Making your passenger sit in the rear seat makes it land real nice
Same in this part of globe. Especially for side by side two seater in ul category, then your main load weights 40-45% of mtow. But if building your design is crazy - building you design from non tradicional planform is crazy^2. But, yes, its allow you to have best view possible... And some extra wing vortices for more drag
Returning to the original poster's proposal ... a 3-surface, single-seater would operate at such low Reynolds numbers that it would require extremely precise construction and would still be less efficient than a conventional airplane. Those tiny chords won't produce much lift and they will easily stall. From my perspective, the only advantage of a 3-surface plane is easier access to the cockpit.
I would prefer to follow Barnaby Wainfain's Facetmobile and build a small, single-seater delta. The delta allows a comparatively large Reynolds number on wing root airflow.
Bart Ver Hees' Delta and Delta 2 are more to my aesthetic tastes.
I would prefer to follow Barnaby Wainfain's Facetmobile and build a small, single-seater delta. The delta allows a comparatively large Reynolds number on wing root airflow.
Bart Ver Hees' Delta and Delta 2 are more to my aesthetic tastes.
wizzardworks
Well-Known Member
The prototype Piaggio had aerodynamic balance issues and was speed limited. The canard was an after thought patch. I flew my design
in X-Plane and had similar issues. Due to the different canard airfoil, canard wing loading, and angle of attack changing the lifting
moment the predicted speed was 334 MPH with 750 HP. Not exactly efficient. Adding the third surface to produce a countering
aerodynamic moment at speed raised the predicted speed to 531MPH on 475HP. The third surface was essentially an inverted "V" tail
which also did away with adverse yaw. The layout is high wing with 3 degrees anhedral NLF747-315 root/ NLF747-415 tip airfoil, full flying
canard (with flaps) and no sweep or dihedral, The inverted "V: tail is an inverted Eppler 561 airfoil. All aleirons elevators and flaps are 25% of chord. There is a thread "How I am building my fusaloge mould" that shows the hard parts, the wings other than corrugated spars (Orion)
have fairly simple moulds. Engine is a 5 rotor using Mazda rotors and stationary gears and redesigned parallel flow cooling endplates.
Power off in the simulator with full back stick has slight wing rocking side to side. Flaps up landing speed is 62MPH in the simulator.
in X-Plane and had similar issues. Due to the different canard airfoil, canard wing loading, and angle of attack changing the lifting
moment the predicted speed was 334 MPH with 750 HP. Not exactly efficient. Adding the third surface to produce a countering
aerodynamic moment at speed raised the predicted speed to 531MPH on 475HP. The third surface was essentially an inverted "V" tail
which also did away with adverse yaw. The layout is high wing with 3 degrees anhedral NLF747-315 root/ NLF747-415 tip airfoil, full flying
canard (with flaps) and no sweep or dihedral, The inverted "V: tail is an inverted Eppler 561 airfoil. All aleirons elevators and flaps are 25% of chord. There is a thread "How I am building my fusaloge mould" that shows the hard parts, the wings other than corrugated spars (Orion)
have fairly simple moulds. Engine is a 5 rotor using Mazda rotors and stationary gears and redesigned parallel flow cooling endplates.
Power off in the simulator with full back stick has slight wing rocking side to side. Flaps up landing speed is 62MPH in the simulator.
Wild Bill
Well-Known Member
Years back when I first looked at this configuration; The general rule of thumb was that the forward wing (canard) needed to be more heavily loaded than the main wing. Just as if it were a typical canard.
My interest in it was driven by the fact that you could build a really small single seater with heavily reclined seating. This way you avoid the upright seating with a tall canopy like on the cri cri for example.
The full size version of this would put the rudder pedals at the rear edge of the canard and the pilots head just over the main wing.
Flights from the test model look promising. But scaling it up for manned flight is a whole other ballgame. Lots of details in a tight space.
Here’s some in flight pics of the model for inspiration.
My interest in it was driven by the fact that you could build a really small single seater with heavily reclined seating. This way you avoid the upright seating with a tall canopy like on the cri cri for example.
The full size version of this would put the rudder pedals at the rear edge of the canard and the pilots head just over the main wing.
Flights from the test model look promising. But scaling it up for manned flight is a whole other ballgame. Lots of details in a tight space.
Here’s some in flight pics of the model for inspiration.
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Thanks. It looks like you controlled pitch using elevators on the rear surface. A point made by advocates of the 3 surface design is that pitch control is more positive for the 3 surface plane at high AoA, compared to a 2 surface canard. If we force the nose up past the critical AoA of the front surface and stall it, the tail is still flying and can be used to control pitch rate change though the nose will still drop when the front canard loses lift.
I'll put more stock in the claims for the superior efficiency of 3 surface designs when they start setting appropriate records.
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It was designed to have canard withou fixed aoa, it is being controlled by that extra set of surface behind it.
Highplains
Well-Known Member
I always liked the AT3 three surface design by Rutan. A model of it was built and flown by a RC modeler I used to fly with, and the results were quite surprising. At a weight of slightly over 5 1/2 pounds and only 400 square inches it floated around like a glider with a pair of OS .25 engines. I suspect the vortex of the front wing interacts with the rear wing.
Interesting. The web site reports the development through about 2014, I hope they've continued to make progress. If the front surface pivots and has an AoA unrelated to that of the main wing, I'm not sure if/how the plane can have the "stallproof" attributes of the now-typical canard aircraft.
All stopped due to financial issues.
{W}, I like the pictures of your 3 surface project, similar to the Piaggio, but it will have the same problem with the props being in the strong vortex of the canard tips.
As I see it, Rutan had the prop always out of it.
I saw a lot of Piaggio take off, or land, and a very odd (prop?), strong noise is produced.
You probably know French designer Albessard and his Triavion built in 1926, with the pursuit of safety,
thanks to a soft stall. 3 surfaces planes have a complex aerodynamic, with all the choices to make, but done right, can achieve many goals. Look at the modern swept forward fighters, also 3 surfaces. Good luck.
As I see it, Rutan had the prop always out of it.
I saw a lot of Piaggio take off, or land, and a very odd (prop?), strong noise is produced.
You probably know French designer Albessard and his Triavion built in 1926, with the pursuit of safety,
thanks to a soft stall. 3 surfaces planes have a complex aerodynamic, with all the choices to make, but done right, can achieve many goals. Look at the modern swept forward fighters, also 3 surfaces. Good luck.
Wild Bill
Well-Known Member
When one of those Piaggio’s flies over at 30,000 I can usually distinguish it from everything else because of the noise it makes. The test model makes plenty of noise too. I’ve tried 3 blade props to see and it wasn’t noticeably quieter.
That wouldn’t be an issue for me. Looking and sounding unique gives it more “ramp appeal”
could you imagine showing up at the pancake breakfast in a 16’ span version of this thing? Some would find it interesting.
I don’t consider it to be safer, practical, better, more efficient, etc.
I think most agree that practical airplanes are in tractor configuration with really good flaps/landing gear.
I never really have understood designs like the Triavion. In its case the largest wing is up front. A look at the landing gear shows that it was balanced near the trailing edge of the front wing.
So the front wing is doing most of the work, with the aft wing kinda going along for the ride.
erkki67
Well-Known Member
this builder had a genius idea how to reduce the noise on a pusher prop
{W}, Well, your model has also that "Piaggio" noise, interesting.
A normal high performance plane with a high Aspect Ratio wing, has a small cord --> narrow CG range.
By the 3 surface airplane the lift is shared between the 2 front wings and is kind of a wide cord wing, having the benefit of a wider CG range, as long as the front wing stalls 1st. Flaps can be used on both wings too.
With a small canard in front, it's still the main wing that carry most of the load and isn't optimum to get the "wide" cord effect. The Triavion is the opposite, and the load sharing is more balanced, I believe.
In the 1920 tys, with short nosed airplanes, the CG was often to far back, making the plane dangerous.
With the Triavion the back wing could carry more with a CG to far aft and still fly with a stable predictable behavior. The advantage of the 2nd wing being 100% in the downwash of the front one, is that it delays it's stall angle of attack a lot. (picture is an extreme example) By a canard, only the "shadowed" part of the wing benefits from the downwash effect delaying stall. The main wing exterior portion flys in "clean" air and could become critical.(stall)
For your model, I would avoid some prop issues, increasing the canard span, or by puting the engines closer together, like the Velocity V twin.
A normal high performance plane with a high Aspect Ratio wing, has a small cord --> narrow CG range.
By the 3 surface airplane the lift is shared between the 2 front wings and is kind of a wide cord wing, having the benefit of a wider CG range, as long as the front wing stalls 1st. Flaps can be used on both wings too.
With a small canard in front, it's still the main wing that carry most of the load and isn't optimum to get the "wide" cord effect. The Triavion is the opposite, and the load sharing is more balanced, I believe.
In the 1920 tys, with short nosed airplanes, the CG was often to far back, making the plane dangerous.
With the Triavion the back wing could carry more with a CG to far aft and still fly with a stable predictable behavior. The advantage of the 2nd wing being 100% in the downwash of the front one, is that it delays it's stall angle of attack a lot. (picture is an extreme example) By a canard, only the "shadowed" part of the wing benefits from the downwash effect delaying stall. The main wing exterior portion flys in "clean" air and could become critical.(stall)
For your model, I would avoid some prop issues, increasing the canard span, or by puting the engines closer together, like the Velocity V twin.
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Richard Schubert
Well-Known Member
I have posted this here before, still deciding on an engine.... this image is about 3 years old at this point
