Higher CLmax?

[Firefly-YCTTSFM]

When you extend a flap on the wing, it does not allow the wing to go to a higher AOA. Contrary to popular belief, it usually reduces the maximum AOA that is possible without stalling.

Ahh! You are correct, I had completely forgotten that. Well, that certainly simplifies things then: no reason to worry about changing the stall angle of the canard. Scrap my last 5 posts.

 

Sorry Marc (and all), I didn't mean to labor the point, I was trying to figure out if I could change the stall angle of the canard. I wasn't trying to balance the forces & moments yet.

[Vortal]

 

edit :

loosing your engine does pitch your nose down... if you don't take in acount your CG moving aft super quick blablabla..

i was in my car and thinking that if you loose your engine, your cg is going to move forward not aft!!! okay guys disregard my blahblah edit, its completely wrong... sorry (marc, no need to blast this one out, i did it myself!)

[airnico]

I have read on the forum that leading edge devices cannot be used on the roncz 1145 because being this a laminar flow airfoil it is not compatible with them.

may you please give me more details about this topic?

I would like to understand how the laminar flow is modified by a leading edge device and what happens in this case.

[Vortal]

I have read on the forum that leading edge devices cannot be used on the roncz 1145 because being this a laminar flow airfoil it is not compatible with them.

may you please give me more details about this topic?

I would like to understand how the laminar flow is modified by a leading edge device and what happens in this case.

actually the slats are for the wings (eppler 1230 mod), not the canard, and the canard are all ready using flaps as ailerons

correct me if I'm wrong, the slats do increase CL max but also reduces Cm.

[airnico]

slats allow a higher AoA, the wings have less incidence than the canard, so why to allow the wings to fly at a higher AoA if the canard has already stalled?

[Marc Zeitlin]

... the canard are all ready using flaps as ailerons

correct me if I'm wrong...

The "flaps" on the canard are elevators, not ailerons. The ailerons are on the main wing, and are used for roll control, while the elevators on the canard are used for pitch control.

[Vortal]

The "flaps" on the canard are elevators, not ailerons. The ailerons are on the main wing, and are used for roll control, while the elevators on the canard are used for pitch control.

Ok! sorry for that don't quite got the terms yet...

[Emile]

I just registered as a new member, but as a non pilot I may be totally outof place here. 

my game is kite hydrofoiling and I am looking for some advice on building  a canard hydrofoil that is designed for straightline speed.   hydrofoil kiteboards are weight balanced in pitch  and directional control is much like riding a bicycle. there are no control surfaces, everything is fixed.  My question is about pitch stability.  There is an existing canard hydrofoil called the zeeko spitfire. its canard has about 3 degrees more incidence than the main wing.   At speed, hydrofoils operate at les then 0,5 degrees of incidence,  so the configuration will end up traveling with negative incidence on the rear foil.  Shifting the center of lift, forward and beond the canard.    To avoid this, the canard could be made very small, but this is would reduce pitch stability which is needed to maintain flight in a one foot vertical window.   Also the high angle of attack on the canard wil cause flow separation at speed, because water is heavy.

My most favoured option would be a canard or a tandemwing  where the front wing has the same angle of attack  as the rearwing.   Who can tell me if this would still yield a good pitch stability,  or is the pitch stability lost when the  a.o.a. of the  canard or frontwing is reduced below a certain number.  

happy to hear your comments. 

thx,  Emile

 

[Kent Ashton]

Never seen such hydrofoils discussed on this site or any other canard airplane forum I've had experience with but I see kite hydrofoils discussed using the google search "kite hydrofoil forum".   The use of "forum" in the search seems to bring up discussion groups. 

 

[Marc Zeitlin]

4 hours ago, Emile said:

My most favoured option would be a canard or a tandemwing  where the front wing has the same angle of attack  as the rearwing.   Who can tell me if this would still yield a good pitch stability,  or is the pitch stability lost when the  a.o.a. of the  canard or frontwing is reduced below a certain number.

If you want static pitch stability, the front lifting surface on ANY aircraft must be at a higher AOA and be more highly loaded than the rear lifting surface. While there may be ways to modify the existing kite hydrofoils to have lower drag (which Is what I assume you're after) this rule cannot be broken and still have static pitch stability. So the simple answer to your question is "No, you can't have the same AOA on the front and rear lifting surfaces and still keep pitch stability".