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Author Topic: Cattywampus 2 E20  (Read 312 times)
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dohrmc
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« on: July 06, 2017, 10:22:17 AM »

Cattywampus is no more. The built up fuselage was too fragile, and easily damaged. I thought a built up fuselage could prove lighter, but my skills were not up to building something that light, and sufficiently strong. That was the designs major flaw-fragility.

Performance wise, it had an extremely fast climb and a very good glide. I have heard many say, "Canards don't glide well".
This one does. I took a leaf from the Doug Joyce book, and made the stab half the wingspan. Seems to work well.

Here is the redo. Still overweight, but only by 1.4 grams. (Number one was heavier).  I am pretty sure I won't be breaking lots of cross members in the fuselage.

Glide tests are very encouraging. I am playing around with the cg in these photos- motor and battery taped on. So far, so good.

I have gone to a pylon mounted motor, as getting the cg right with the motor in the back required too much ballast. Never done a pylon motor mount before, so we will see how it goes.

The bright red bits are pink builders foam, sealed with dilute Elmers glue and painted with acrylics. This stuff is light-added .2 gram to the total weight. I will likely put a streamlined piece on the very back if it is not too heavy.

I hope to get this figured out this summer. Major kitchen redo is keeping me home and away from the Nats.

If any of you have ever used a pylon mounted motor, feel free to let me hear the pros and cons.
Attached files Thumbnail(s):
Cattywampus 2 E20
Cattywampus 2 E20
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PaulBrad
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« Reply #1 on: July 07, 2017, 09:26:34 PM »

Very interesting model Dohrm. I am looking forward to your flight reports. Sure do wish you were able to attend the Nationals this year. It would be great to see the model in action.

Paul Bradley
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frash
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« Reply #2 on: July 07, 2017, 10:22:04 PM »

Dohrm,

Several years ago, I lightened a Swedish sport rubber canard called Gammon for indoor rubber power, and later converted it into a capacitor electric with a pylon mounted motor. Sport flying was done in the Johnson City, TN Mini-Dome.

http://indooraero.homeunix.net/gammon.shtml

I think that I should copy your canard E-20.

Fred Rash
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dohrmc
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« Reply #3 on: July 08, 2017, 07:22:41 AM »

Paul and Fred, thank you.  Presently getting the cg nailed down for best glide. The pylon is just held on with rubber bands and can be moved fore and aft.
The best glide so far is with the front end of the stab jacked up about 1/16". (A toothpick width-I am very scientific).

Fred, copy away. Just build the stab strongly as it takes a beating. I don't have a plan, just John Wayne'd the whole thing. I had read a lot of info on Doug Joyce's canards, and I copied him. The stab has more camber than the wing, which is a thin camber for a faster climb.

Those tissue strips under the covering allow for light but stiff construction. No warps so far.
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jj
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« Reply #4 on: July 08, 2017, 08:47:47 AM »

Years ago, the Aeromodeller published plans for a model called 'Mccannard'. This had the motor (glow in those days) pylon on the CG, which should be one wing chord in front of the  wing LE.
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prisms2
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« Reply #5 on: July 13, 2017, 07:07:44 PM »

I'll take exception to the statement that canards do not glide well. I have been flying canards since the early sixty's and I can assure you that canards will glide as well or out glide the best tractor designs around. Check out my father's (Carl Taylor) Cee Bird design (November/December American Modeller).
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