Originally Posted by Gene Bond

John:

An advantage you sort of touched on, would be having the canard stall just slightly ahead of the main wing, allowing for a 'parachute' stall would be very useful in a spot landing contest!

Of course, balancing the stall points would be a stroke of luck, or a lot of trial and error

All purely hypothetical, of course... I'm a great believer in luck!

Gene, When we design a canard we are normally aiming to achieve the balance so that the canard will stall slightly ahead of the main wing. There are many factors in the balance of stall points, so it often needs some luck as you said. However, if the forward wing is purely a scaled down version of the main wing, it should stall well ahead of the main wing due to the physics of the air and the way the reynolds numbers affect wings of different sizes.

I think the spot landing contest still requires some form of brakes to control the descent rate. For my slope soarer I will try crow braking, which is something I haven't seen on a canard sailplane before. I am not confident that a canard would be a good choice for a thermal duration sailplane, but I think the gentle stall behavoir seems attractive for this type of model.

Charles, as you suggest I am using quite a short distance between the wings. There will be only 21cm (8 1/4") between the trailing edge of the canard and the leading edge of for main wing. The short coupling should mean that only small elevator throws are needed for the elevons. The centre of gravity will initially be set for 10% static margin. I hope to achieve ideal canard stall chacteristics, but it will be interesting because the elevons should allow the model to be pushed further into the stall than if using a conventional canard elevator.

John, I am looking forward to seeing your completed slope soar-er. It would be nice to know your incidence and decalage figures. Charles

For the incidence angles I have set the main wing at so its chord line has 0.5 degrees positive incidence relative to the fuselage reference line. The forward wing is mounted so its flat bottom is parallel to the reference line, which gives its chord line around 1.6 degrees positive incidence. Overall there is 1.1 degress decalage angle between the two wings.

I have been working on the fuselage consturction. It is reasonably solid as the sides are made from 4mm balsa. The construction is very similar to the other two canard models I have made. The forward wing is mounted lower than the main wing, so I decided to put in a "canopy" shape just in front of the main wing to help with stream-lining. Normally I don't bother with this kind of detail, so hopefully it will fly and be controlable...

Thank you, John. The incidence set up is interesting. I suppose you will have just two servos and no motor? About what speed do you expect? Charles

I am still quite new to slope soaring so I don't really know what speed to expect. I have built this model for moderate conditions which means around 10 to 15 knots wind speed. I am interested to see the performance of this model compared to the flying wing models we can typically see at the slope. I hope there will be at least one area of flight where my canard will show some good qualities.

The model will use 4 servos. 2x HS45 for elevons, 1x HS65HB for flaps, and 1x HS45 for rudder. There is no motor for this one.

The wires from the speed controller were passed through the rear bulkhead and soldered to the motor. The top formers were added and a 1/8" square balsa stick was glued in. I promise to spend more time building in the future. Charles

Sheet balsa stiffeners were glued in around the canard mount. A nose gear was formed from 0.055" wire. The top front of the fuselage was re-enforced with 1/8" sq. stringers. A 1/8" dowel was installed into the front of the canard wing. Charles

I have finally finished the construction phase of the project. The work that remains is mostly painting and covering. All of the radio equipment will be located under the main wing. The receiver battery will be accessed by removing the forward wing.

That's a great looking canard. John! It looks fast. Please keep the news coming. Charles

Charles, Thanks for the comment. You suggested to make it short. Were you thinking it should be shorter than that?

John, you give me too much credit, but if you draw a line connecting the wing tips, you seem to have a nice delta shape which in my opinion needs elevon control to work well. I believe it is shaped about right just by looking. If there was an elevator, it would not have a great effect with the short distance to the CG. With a long distance between the wings, you would need elevator control as I see it. I feel that speed will be helpful to your model and wish you the best with it. Charles

Charles, I was interested to know what you were expecting. I think it is still a bit experimental, so I am far from a conclusion about what is the correct design parameter in terms of length. If it is too short I worry if the interference of the canard wake may affect the performance in an unpredictable way. I just hope to have a design that is conservative enough to be flyable and hopefully learn something from it.

Just to let you guys know that Charles was building great planes way back when.
And Old Flying Friend