windscout

Hi Drew,

Just thinking about the difference of a standart 15m glider and a 15m glider with flaps, in particular at higher speeds, made me wunder if I did not realize something fundamental. Those flaps make a big difference in performance at higher speeds.

It is my understanding, that the big advantage of the canard design aerodynamically is the low wetted area, which is reducing drag. Not having the possibility to change the airfoil shape during flight is giving up some of this advantage.

But I see your point, that there may be many other ways to which are simpler to get higher speeds. However flaps could eventially at the same time increase lift during takeoff and so get the plane airborne sooner.

unfortunately, I am not yet a canard builder and can not start the process in the near future, but I did built extencively model planse in the past and did work some time in a glider repair shop. I hope to get on a project some day. At this point in time, I am in the stage of trying to better understand why certain things are not being done or not, knowing that if I do not see a reason for something does not mean that it is necessarily a wise thing to do...

Thanks for your thoughts

Thanks for the reply!

 

My idea to build a Vari or Long is not to get a cheap and fast airplane fast, but to enjoy the building "the best/slickest/fastest" I can.

I make a living flying, so this is not the concern for me....

 

So if laminar would bring a few kts I would try it, however the goal is not loosing any low speed properties...

 

To the canard:

Why should a trimable canard be unstable??

The canard itself is stable, isn't it??

So my rational (..which may not be rational after all ) is -

If high CL at max speed is not trimmable by elevator only, why not change the incidence angle (?).

IU the max CL causes a high AOA that is not trimmable by elevator any more and needs excessive stick-forces....

 

This would probably be a rather small amount (3-8º ??), It also can be a slow electric-motor or a long (manual) handle with little effective movement on the canard.

If the canard is stable it should not become unstable by changing the incidence.

To protect against "un-intended" stalls on the mainwing one could limit the aft-stick movement with application of lower incidence. So pulling aft will only generate a faster minimum speed. Increase incidence (Return Canard to original setting) and one gets the full range back....

I do understand that things get more complex here, but I wonder what the benefits regarding speed would be.

 

Ever anyone tried a full flying canard?

 

Best Regards,

 

thjakits

Hi,

very interesting, i am thinking about this for some time, and did not find a reason yet on why a canard or flaps on the main wing should not be possible, given that the canard could be equiped with a trim. I understand that this would require a compensation, which I would expect can be adressed by a controller or auto-pilot.

Thinking back to the time I was still flying gliders, it is not unusual that some pitch is required when using the airbrakes or flaps in the final, and it is not of any concern. What would be so different with a canard-plane?

I am very well missing something, any thoughts?

Regards