On Wed, Nov 5, 2008 at 9:21 PM, Ron Jensen wrote:
> Assuming we're talking about the Malolo1 as modeled in CVS, I looked at
> it the other day when I was looking for elevon examples. From the AC3D
> model the Malolo1 should maybe have elevons but the JSBSim flight model
> doesn't use them... Are you interested in having this flight model
> changed to use elevons instead of separate elevators and ailerons?
The Malolo1? That's sitting here next to my computer leaned up against the
wall just looking pretty. I still *really* like it's lines, but we have
moved on with several new revisions and improvements.
http://baron.flightgear.org/~curt/tmp/2008-10-28--15.04.41/00032.jpg
http://baron.flightgear.org/~curt/tmp/2008-10-28--15.04.41/00038.jpg
http://baron.flightgear.org/~curt/tmp/2008-10-28--15.04.41/00039.jpg
http://baron.flightgear.org/~curt/tmp/2008-10-28--15.04.41/00014.jpg
The new airframe has a *really* nice blended body center section. The wings
plug in are are replacable. We have experimented with a couple airfoils,
different wing areas, wing sweep, and different vertical stabilizer
configurations. We also shaved about 2 lbs of weight for the newest
airframe which is significant since that is equivalent to about an hour's
worth of battery.
In fact, on Monday I did a > 1 hour flight, and 60 minutes of that flight
was powered and under total autonomous control. That's no where close to
any kind of a record, but it's a really nice milestone for us, especially
since we know we could trivially extend that to 2+ hours by adding more
battery and we know we already have the capacity to carry the extra weight.
If anyone cares, the wing span is just under 8' now. It's constructed of
foam core covered with carbon fiber, kevlar, and fiberglass depending on the
strength/weight needs of different portions of the airframe. The all up
weight with autopilot, camera, and 1 hour worth of battery is about 9 lbs.
It is capable of being fully "marinized" and is able to land in the ocean
and all the important bits are sealed and protected from salt water. It
cannot take off from water, but instead is designed to be hand or catapult
launched. We over engineered it to be extremely strong and robust.
Operations at sea are very hard on equipment and this airframe needs to
stand up to abuse. In our field test last spring, on one recovery, the
small boat that was picking it up out of the ocean was lifted up out of the
water by a wave and slammed down on top of the wing. In another situation
we almost had a 240' NOAA ship run over it. We can't make it out of 1/4"
steel, so this is the next best thing. :-)
Top speed is hard to say and depends very much on power and prop. We are
shooting for efficiency and longer flight times, not high end speed.
However, I do have data from one flight clocking the wing at about 88 kts in
a dive. Later I put on a speed prop for fun and I know I was hitting even
higher number, but I don't have any hard data to say exactly how fast.
Typical cruise speeds under autonomous control are in the 35-50 knot range.
One day I took some time at the end of a test flight to have some fun. I
could start at one end of the field at a couple hundred feet AGL, wheel
around and do a diving pass at eye level power off. Then hit power at the
other end of the field and climb out. If I do that under full throttle, it
really screams and the fly-by's and subsequent climb outs look very "jet"
like. The newest airframe is really clean, so power off high speed passes
are very quiet too. I've experimented (leaving myself maybe a 50' buffer)
with doing a high speed power off dive, followed by a power off loop ... I'm
not able to pour water into a glass throughout the whole maneuver, but it's
still pretty impressive looking from the ground.
We don't have rudder control, but the airframe is capable of rolls, loops,
inverted flight, and most of the basic aerobatic things a person might want
to do. Ultimately it is designed to be a truck, but every once in a while
it's fun to wind out the motor and do some high speed passes to impress the
gophers and squirrels. :-) It's also fun to go up on days with thermals and
join some of the hawks that fly around. It's very easy to see up and down
drafts in my flight data, and this airframe will definitely thermal in the
right conditions.
This serious aspects of this project are sponsered by NOAA. NOAA is already
involved in a variety of projects involving debris location and removal at
sea and on protected reefs and islands. They are also involved in wildlife
management, especially protected species such as the monk seal and sea
turtles. So the purpose of this project is to see if a small, quiet, "low
cost" UAV could assist in these efforts which are already ongoing.
There's nothing earth-shatteringly new in any of this, but it has been a lot
of fun to be part of the process that has taken this project from the idea
phase through a couple prototype revisions to what we have now. It's still
a work in progress, but it's starting to get close to what our initial
concept hoped for.
What was your question? Oh yes, certainly if someone was interested in
making some tweaks and updates to the 3d model, that would be awsome. I've
learned how to do a few things in my life, but 3d modeling is something I've
always really struggled with. And if there are ways to improve the flight
model and make it closer to the real thing, then please, I'd love to work
with you on that.
I'm nearing the point where I could start to think about doing some
automated/consistent flight testing to hopefully generate high quality data
(versus just flying around aimlessly and collecting that data)
Please don't kill yourself! We need someone with write access to maintain
> the CVS server ;)
>
How does that saying go? "Someone cracked my password, so now I need to
come up with a new name for my dog."
Regards,
Curt.
--
Curtis Olson: http://baron.flightgear.org/~curt/
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