Canard wing on a Bensen or similar?

[cook11]

Has anyone ever experimented with a canard wing with trim control or fixed on the nose of a Bensen or something similar? Curious to know how well a mod such as that would do for pitch stability control along with a horizontal stabilizer such as the one offered by Ron Herron?

 

[Alan_Cheatham]

Aerodynamically canards function different than a horizontal stabilizer and would be destabilizing on a gyroplane, much like an arrow being shot tail feathers first.

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[phantom]

canard wing on a bensen

canard wing on a bensen

I have used a small canard to counter the downward push of a large windshield but I wouldn't use one on most gyros due to the size of normal stabilizers, mine are at least 6 feet and some are bigger. back when I used bungees on skis instead of springs it was not uncommon to break a frozen bungee and if the nose ski had a broken front strap it would try to pull the nose down and it took more power to fly but if the back strap broke and the nose ski pointed up it took less power. without a large HS I think something as simple as a broken bungee could cause a crash as could a canard wing.

Norm

 

[NoWingsAttached]

You may be interested in the WRENS fly-in thread photos from this past October. A very well-built gyro with a canard showed up, and flew. Beautiful machine. Not sure how well it flies, the owner was very happy with it.


http://www.rotaryforum.com/forum/showthread.php?t=31521

 

[Doug Riley]

A true canard (an unloaded H-stab forward of the aircraft's CG) is de-stabilizing. Canards fell out of fashion very early in the development of airplanes for this very reason.

The Rutan variant of the true canard is actually a small second wing. It operates in lifting mode. It's designed to stall before the main wing, dropping the nose and preventing the main wing from stalling at all.

On a gyro, however, we don't have to worry about stalling the rotor. Having a lifting canard that can stall and drop the nose is very unhelpful on a gyro.

 

[NoWingsAttached]

A true canard (an unloaded H-stab forward of the aircraft's CG) is de-stabilizing. Canards fell out of fashion very early in the development of airplanes for this very reason.

The Rutan variant of the true canard is actually a small second wing. It operates in lifting mode. It's designed to stall before the main wing, dropping the nose and preventing the main wing from stalling at all.

On a gyro, however, we don't have to worry about stalling the rotor. Having a lifting canard that can stall and drop the nose is very unhelpful on a gyro.

Doug

I often learn things like this, that I never had a notion of, from you. The first (Wright) airplane that flew had an unloaded canard, right?

 

[j bird]

Doug, If I installed a 12" x 36" wing shaped piece of aluminum on the keel under the prop on a Dominator, do you think that would increase the stability at all ?. I have a Corvair engine on a single seat, the 3 bladed Warp is 3'' from the vertical stab. It hasn't flown yet. I had to make new cheek plates so it would hang at 1o* which Ernie recommended. Would it help with that heavy engine?

 

[Doug Riley]

Greg, I don't know the CG location of the original Wright Flyer, but it was pitch-unstable. If there was ny load on it, it evidently wasn't enough.

John, an H-stab that size under the prop will do a little for you at higher cruise speeds; nothing at all at low speeds. The stock Dominator flies beautifully, thanks to its thrustline below the CG and immersed H-stab. If you lose that rudder-mounted H-stab, you'll lose much of what makes a Dom. such a nice-handling ship. No way a keel-mounted H-stab can replace it.

 

[j bird]

Doug, I'm not talking about losing the rudder-mounted H-stab, but,adding a 12"x36" on the keel under the prop area. I've already sucked up a small rock taxiing and took a hunk of blade out. I'm just wondering if a rock guard that size would destabilize the Dom.?

 

[Doug Riley]

Jay: As long as it's aft of the CG, not ahead of it, and has zero incidence, it will add stability at higher speeds. Should be no problem. Jusy secure really well and inspect carefully. It wouldn't be pretty if the thing came off in flight.

 

[GraemeClarke]

Ken Wallis used small canards on his machines. Said they worked well.
Graeme

 

[Doug Riley]

Wallis and a few other people have used them to reduce the "tucking" tendency caused by windshields and pods. Of course, the canard is then being used in lifting, or loaded, mode.

IMHO, however, it is still more wholesome to use a rear-mounted H-stab for these purposes -- after first designing the pod and windshield to produce as little nose-down trim effect as possible.

 

[Redbaron]

I was noticing your gyro in your avatar, grame. what is it? did you build it? the tail stickin way out caught my attention mate!

Ken Wallis used small canards on his machines. Said they worked well.
Graeme

 

[GraemeClarke]

I copied bits I have seen all over the place. A lot from lurking on this and previous forum. I miss Mr. Wall.
Graeme

 

[j bird]

Thanks Doug for your input.

 

[hiphop]

Canards for increased pitch damping

Canards for increased pitch damping

There are several tricks you can play with horizontal surfaces to improve the aerodynamics, given the structural limitations. One of these specifically is using a canard *and a tail* to increase pitch damping.

Pitch damping (note: not pitch stability), is roughly a function of tail volume, which is area x moment arm from cg. On a gyro, unless you have a long boom or a very large tail, this is going to be small.

One trick you can pull is to place a canard forward of the cg, and a tail aft of the cg. The forward canard is destabilizing, but its area adds to the tail volume, hence increasing the pitch damping. You just have to make sure that your tail is large enough to overcome the destabilizing input of the canard.

Hope this helps.

--G

 

[Doug Riley]

Gabriel: Many amateur-designed gyros desperately need better static stability. That's because rather large and variable forces are distributed willy-nilly about the CG (especially airframe center of drag and engine thrustline). While what you say is true (horizontal surface on either side of the "circle" around the CG improves dynamic stability), dynamic stability doesn't become an issue until static stability exists.

Therefore, IMHO builders should concentrate on adding H-stab volume aft. In most cases I'm aware of, if normal static stability is established, dynamic stability will be taken care of as well, even with our short tail arms.

This is especially true when using today's gyro rotors, which tend to be more massive, and to turn slower, than rotors of yesteryear. They therefore contribute more damping of their own, if only the aircraft can be prevented from flipping upside down.

 

[j bird]

The Dominator H-stab. has a total area of 4.3 sq.ft. if I install a flat plate with 3 sq.ft. under the prop well back of the cg. that would increase the H-stab. area to 7.3 sq.ft.
Understandably the flat plate would be out of the prop blast. At least I wouldn't suck up any boulder's.