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Old Dec 20, 2004, 07:47 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Wattage Micro Flyer Mods

As has been suggested in the Wattage Micro Flyer (WAMF) Thread #2 it might be useful to have a thread just to summarize modifications people have made. Here are the rules of engagement.

(1) No chit chat in this thread. Chit chat posts will be deleted. We are trying to keep this thread short.

(2) Post your modifications, and wherever possible pictures to go along with it in this thread. If you see a modification you think worth including in this thread in one of the other WAMF threads, please PM the author of that mod and ask if they would post that in this thread.

I'll add this thread to the "Micro Thread Index" for easy future reference.

Hopefully Del will jump in and start this thread off with his nice set of mods.

Gordon
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Old Dec 20, 2004, 11:00 PM
del
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WAMF electronics mod's, a start.

Friends,
After having taken three WAMF models apart on the way to
transplanting the electronics into a new model, I've built up a bit
of experience. As a start for kicking this thread into action, here's
an introduction to the surgery required for removing the vital organs..

Other WAMF modifiers, and there are quite a few, have different rituals.
Any that work are good. But, this is what I've come to do.

1. Take off the wing and horizontal tail, and pull the rudder away from
the vertical stab until the rubber bands come out of their sockets.
If you get the wing off intact, its a potential nice part for other projects
but not necessary.

2. Starting at the nose, peel the fuselage apart. I find it best to try
to peel away the left side (as seen from the pilot's point of view)
leaving the other side flat. That's because the antenna and
actuator wires are glued to the right side of the fuselage.

3. Stop when you get close to the battery box. Try to get that
off in one chunk of left side foam. Its a nice light part. But if
ya fail, not a big deal, you can make one from balsa or use
another LiPoly cell without the WAMF battery box.

4. The tricky part comes now. Trying to get the rest of the
fuselage left side off without messing up the actuator wires.
Slow and careful is the rule here. But as long as you have
enough magnet wire left sticking out of the coil to make a solder
joint, you're ok.

5. Study how the coil is taped onto the vertical stab. Get rid of
the tape and the coil should easily come away.

6. Now pull the guts out and toss the right side of the fuse. Take
a look. Make notes about what's hooked to what. Be sure to
note the polarity of the wires from the battery !Important!,

7. If you got all the wires out intact you could stop here and go build
a model for the electronics. But I always go further. For sure if you
want to have a model with a longer tail, you'll need to do some
additional hacks.

8. Going from the motor aft.. The motor is stuck into the fuselage
with some sort of silicone. I get as much of that off as I can.
But then you find that the front of the gear case was held on by the
silicone! No problem. A dose of plastic cement like "Plastruct" fixes
that. In the worst case, if the gearbox gets destroyed, or if
you want to get rid of the heavy gearbox, still no problem.
I've used the WAMF motor direct drive with a GWS 2.5 X 0.8 prop
to good effect on a light stick model.

9. Every WAMF I've taken apart had globs of nonstructural silicone
around the back of the motor. And it was all over the solder lugs.
Clean as much of that away as you can. Tooth picks, knives, whatever
it takes. If anyone knows a good solvent, let me know. Ya need to get
solder access to the lugs on the motor.

10. Now we play with fire. Assuming your notes are good, unsolder
everything! The wires used for the motor, battery, and antenna are
_way_ too heavy. Replace the antenna wire with Litz or other light wire.
If you know what model your're gonna put the hacked parts in, and
where the parts will need to be to get the center of mass right, you
could just replace the wires by soldering in new lighter ones. But if
you know that, you're smarter than me, so..

11. Pick the connectors of your choice and solder them on the
battery, motor and actuator solder pads on the RX. I'm cheap
so I make my own connectors out of 0.1 inch center integrated circuit
sockets. I make sure to make the polarity of the battery connection
obvious by stuffing on some red and black heat shrink tubing.
(I have been known to "let the smoke out" of circuits at the flying site
so I try to make that a difficult mistake to make.. The polarity of the
motor and the actuator circuits are not important. If the prop turns backward
or the rudder works backward, just reverse the polarity of the connections.

12. Soldering longer wires on the coil leads can be a pain, but it's not
all that bad. With a nice hot iron, the magnet wire from the coil can be
nicely tinned. Here again I use Litz wire to increase the length of the
coil leads. Opposite gender connectors on the motor, battery, and
actuator leads and voila! There you have a completed hack of the
WAMF electronics.

Though that might sound complex, it's taken me longer to type it up
than it takes to accomplish (though that might be saying something about
my typing speed....)

I could go on about selecting/designing a model for the hacked electronics,
but no, that's another topic. Suffice it to say that in spite of what you might
have "learned" from the stock WAMF, light wing loading is _everything_...
Light models fly better. :-)

Here are some pix of my WAMF electronics mods. Needless to say,
if there are questions, comments, or criticisms, have at it.

--del
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Old Dec 20, 2004, 11:31 PM
del
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A start at WAMF mod aerodynamics.

Friends,
Attached is a pic of my most succesfull WAMF hacked
model to date. The first model wanted to loose altitude
in a turn. This one doesn't. Why?

I'm not really sure, but if you look at the vertical tail
you'll notice that the rudder hinge line is angled aft.
My assumption was that a deflected rudder along that
hinge line would also add a bit of effective up elevator.
It seems to work....

I'm still not quite convinced that it works. But it seems
like something us WAMF hackers and Bit hackers should
test.

--del
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Old Dec 21, 2004, 02:00 PM
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I just purchased a Wattage Micro Flyer and noted in the thread that some had reported that removing the landing gear to lighten it also shifted the CG too far back.

For this reason I cut away a portion of the fuselage. Now it looks like one of Burt Rutan's planes.

This along with removing the landing gear, mount and decals, saved about 3 grams or about 10% of the total weight (mine now weighs in at 27 gm A.U.W).

Since the power required to fly with the same wing area is WEIGHT^(3/2), this would represent a saving of 15% in the power required to fly.

Sadly, it's too cold and windy to test, but perhaps some others may want to try it.

When cutting, be careful of the plastic reinforcement of the battery connector which extends below the battery box.
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Old Dec 26, 2004, 10:51 PM
del
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Martyn,

Nice mod! Let us know how she flies...

Wing loading is.... er... _everything_...

--del
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Old Dec 26, 2004, 11:40 PM
del
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Yet another WAMF mod model

Friends,
Here's my 4'th hack of the WAMF.

The motivation for building this model came from working with a local group
of folks who _need_ to fly indoors. In order to get access to the gym, we
run model building classes for underprivileged kids. The next model we build
with the kids will be the Peck Polymers "Starved Pussycat", a rubber powered
free flight kit.

So I decided to build a model that started with that basic design, scale it up,
and, with luck, show the kids that with some work ya don't need a bunch
of money to build an R/C model. All it takes is a bit of money, and some effort..

The model has yet to fly. We won't get into the gym again for a week or so.
But it seems to want to fly. (Y'all know how that goes... It's tempting to
try to fly in the house, or in the garden... But it's an _indoor_ model.
So ya put it the box, and wait....)

It came in at an all-up weight of around 19 grams.
The wing span is 20 inches.
The battery is an old 80 mAh LiPoly.
The motor is stock WAMF direct driving a GWS 2508 prop.
I "cheated" by using nice light balsa and Gampi tissue....

As always,
Questions and comments are welcome.

Here's a pic..
--del
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Old Dec 27, 2004, 08:10 PM
TheyreComingToTakeMeAway!
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did you balance the actuator weight with something on the other side?

Derrik
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Old Dec 27, 2004, 11:35 PM
del
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Quote:
Originally Posted by derk
did you balance the actuator weight with something on the other side?

Derrik
Nope, well, sorta, I put the rest of the electronics on the other side
of the fuselage. But, I thought about that too...

It's kinda the weight equivalent of right thrust. But also the
equivalent of FF standard left stab tilt....

We'll see how she goes when I get to test fly it..

--del
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Old Dec 28, 2004, 08:08 AM
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Del that is a nice delta dart looking plane.
I think I have seen similar results as you in angling the rudder.
I thought about attaching a string fromm rudder to elevator on one of my bit planes but just moved the cg back instead.

Billy
[Edit]
oops I just noticed that this thread was the WAMF mods thread appologies for the chitchat. Maybe the rudder string thing is a valid mod.
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Old Dec 29, 2004, 10:56 PM
del
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Billy,
I think that's a valid "non-chit-chat" post. Bit plane, or WAMF...
A friend of mine tried to something similar on a bit model using another coil
and magnet. It didn't work.

The problem seems to come down to the details of trimming.
And the matter of making the results useful to other model builders.

As you might have noticed, I didn't angle the hinge line back on
the Fat Pussycat. So we'll have two points on the rudder hinge
angle line graph, once I get to test fly it...

I can say, however, that I'm fairly sure that my first WAMF hacked
model (also a delta wing) lost a lot more altitude in turns
than the one where I angled the hinge line aft.

But anectdotes do not make a scientific study... ;

Where's a NASA grant when ya need one?
--del
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Old Jan 08, 2005, 03:46 AM
del
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Back in the Gym..

Yee Haa! We're back in the gym!

I showed up with 4 new models to test fly, And, to my surprise,
the one that I didn't expect to go good at all was the one that flew the best.

This WAMF hack has a wing span of a bit under 28". The wings were
made from scraps of foam left over from a friend's work on hot wireing
out foam wing panels. The tail surfaces were cut from disposable foam
dinner plates. And the all up weight came in at over 43 grams!

I expected it to be a "ground hugger" at best. But no. Once it got
trimmed out, the model would ROG and do a nice stately climb up
toward the rafters. Pulsing the throttle button would let it maintain
altitude. The glide was nice. It turned fairly tight both right and left.
It flew just fine.

What amazed me was how well the WAMF electronics, and motor with
a stock gear box and prop, did with such a heavy model.

The potential for mods and hacks of the WAMF are greater than I ever thought...

Just what I need... More projects.......

Anyhooo, here's a pic of the model.

--del
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Old Jan 12, 2005, 05:36 PM
Obstinate spurious drone
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What about putting the WAMF guts into a balsa peanut kit, like Peck's Mitsubishi Zero? Seems like it would work.
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Old Jan 13, 2005, 02:21 AM
del
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That might work, Jeff..

But at Peanut scale, the wing loading would be high, and the model
would be fast. Personally, I prefer models with a lower wing loading.
They fly slow enough to let my tired old brain stand a small chance of
thinking ahead of the model before they hit the basketball backstop...

However, I wouldn't want to discourage you from "going for it"...

At the moment I'm in the "sketch phase" of a profile scale model
that I hope to bring in at under 40 grams using some hacked version
of the WAMF electronics. But it'll be next week before I have the time
to get serious about that..

Right now, I'm working on a mix of foam, balsa, glue, and tissue paper...
This Friday at the gym will tell me if I'm headed in the right drection.
I will report on how the model flies. Wish me luck.

And I wish you the same.

FlyToys R US..
--del
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Old Jan 14, 2005, 09:13 PM
Moderador.
Alfredo Rubio's Avatar
guadalajara, jalisco, mexico
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Del, you are a prolific modeler!!!!!!! nice models, I love the twin rudder-counter-act-torque-magnetic actuator do you think this equipment could be to use in a scale-shape model?
Cheers

Alf
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Old Jan 14, 2005, 11:05 PM
del
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Alfredo, mi amigo!

Yes, if you build enough models, _some_ of them will fly...;-)

The Fat Pussycat was not one that flew. No matter what I did to it..
I've converted it to a rubber powered Free Flight model. But have yet
to test fly that.

The next WAMF hack will be a more "scale like" model.
Though I have yet to choose a subject airplane.

What I seem to have learned is that a model that weighs
50 grams and has a wing area of 150 square inches, (sorry for the mixed
units...;-) will fly with a stock WAMF system. That leaves a lot of
room for experimentation.

Supposedly, there's an old curse, "may you live n intersting times"..
I'd say that's not a curse. In the indoor/micro model world we live in
very intersting times... Could life be better than this?

Su Amigo,
--del
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