| Last sunday John Adair shows up at the field with a Robbe Kormorand,
something I hadn't expected to see in this lifetime, but leave it
to John to have the latest thing.
It's a ~2 meter electric pusher prop canard flying wing. Got that?
Right away you know you're in for some hair raising maiden flights.
John knew it too, and he had drilled a small finger hole in the
bottom of the slick plastic fuselage pod to give some way to put
some thrust into the hand launch. Then there was the problem of
how to get his hand and arm out of the way of the prop as it passed
by at the moment of release.
Four launch attempts later, it was obvious that there was no way
to achieve flying speed by merely running and throwing.
But it was one of the most rugged models I've ever seen. No damage
at all after 4 cartwheels, pancakes, you name it. Even the plastic
winglets were intact. His next attempt will be with a hi-start and
then turn on the motor after the line drop.
Terry
|
| Last night, I finally got a chance to test fly my Kormoran. I had put
the coating on in a hurry before we moved last March just because I
didn't want to lose ailerons or whatever during the move. It had been a
long night, and I'm not at all happy with the quality of the result,
but there is no need to fix it as long as I don't know the thing really
flies... Then came the move and all the work that was involved with
it...
Yesterday was THE day. The weather okay, light breeze, overcast,
nothing great but probably best for maiden flights. I went to a small
hill, assembled everything, checked the controls (especially the
elvator going the 'wrong way') and was ready to go. I ran a little bit
still holding the plane to check the tendency to break out. It tried to
put the nose down, which I assumed was due to not having enough speed.
So I put all my courage together and tossed it. It reached the ground
before I had my hand on the elevator stick. But it's robust, as the
previous reply stated. Since the C.G. was according to the plans, I
just trimmed a little up and tried again. This time, I reached the
elevator stick before the plane touched down. I gave it some more 'up',
and it had a nice glide. So I decided to switch the motor on, and it
immediately picked up speed and height. No further trim changes were
needed. It looks great in the sky with it's unusual configuration. I
like it a lot. It can fly really fast, but slows down nicely, if
needed. Elevator 'up' response seemed to be less than what I liked, but
that's probably due to the canard being close to it's CLmax with my
uptrim. I'll put the C.G. a little back and this will hopefully improve
elevator response.
I did a second flight and it went just as well. During the flight, it
started to rain, so I landed and packed up. I'm a very happy camper!
When all the other 'fixing stuff' is done (put R/C gear into the
FIESTA, assemble the UHU with the geared motor, cover the RACE CAT and
install R/C there), I will probably redo the covering. It may take some
time, but I can go out flying again and I really like the looks of a
canard (especially this one).
My setup is:
wing built in two halfs (instructions call out for one piece)
Aileron control with one (will be two) FUTABA S133 micro servo
Canard (elevator) control with another FUTABA S133
Motor: ASTRO Cobalt 05 (reversed polarity, adjusted timing)
Prop: aeronaut 8*5
Battery: Sanyo SCR 1200 (6 cells only!)
Flight times, thermal ability will be reported with some more
experiences (betteries were not performing well after weeks of lying
around etc.).
Best regards,
Hartmut
|
| Last night, I started to strip down the Kormoran. As noted before, I
wanted to redo the covering anyhow. Several flights last year revealed
that there is a problem with the C.G. - and I can't do much about it! I
already have a layer of lead around the fuse right before the (pusher)
prop, but since the lever arm is so short, it doesn't change much. And
I don't like the idea at all to carry lead with an electric, but I
can't get the battery further back since the aileron servo gets in the
way. Also, I had experienced some severe cases of wing flutter when
recovering from a (fast) dive. I suspect this is due to canard votex
over main wing. And the long ailerons are very soft and only driven by
torsion wires.
What I'm doing now is:
- mount the aileron servos in the wing where the canard vortex
hits the wing. Hope to get rid of the flutter with holding the
aileron exactly at that place
- install stiffer ailerons
This gets the servos out of the way, too and allows more movement of
the battery for C.G. adjustments. I'll keep you posted on the results.
Best regards,
Hartmut
|