|
The
Weed Wacker has a new engine installation. The engine is
from an old Homelite chain saw. It has a lot more power than
the old weed wacker engine. The next modification we did,
was to move all of the servos (except for the aileron
servos) to a central location and use a pull-pull system for
control. The reason for this mod. is to eliminate radio
interference picked up by the long servo leads. The aileron
servos are connected to an interference filter; that is why
they didn't need to be moved. We have updated the
performance figures and the other specifications that are
affected by these modifications.
Original radio
installation (what a mess!).
3/14/99
Today
Sam built the mount for the new engine. It is all welded and
drilled and it fits very nicely.
3/15/99
Today
I (Larry) started work on the pull-pull cables while Sam got
the firewall ready for the new engine and made a wind screen
(cockpit with room for two hamsters or one ferret). Sam also
touched up some of the covering where the fuel had damaged
it.
New radio
installation with servos hooked up.
3/16/99
Today
I finished the pull-pull system, but we were unable to find
a cheap pull-pull setup that would work for the tail wheel,
so I used a push-pull flexible tube system, which isn't very
good.
Chain saw
engine with mount.
3/17/99
Today
we installed the engine, set up the throttle linkage,
covered the rear fuselage and began testing the engine. The
throttle linkage was especially difficult because of the
orientation of the carb., so we still have some bugs to work
out. We are having minor difficulties with getting the
engine tuned in, but we are getting closer. It appears that
this engine will consume a lot of fuel, but that shouldn't
be too big of a problem.
3/18/99
Today
we worked on getting the engine to run right and tested for
radio interference. It turns out that the problem with the
engine was that Sam had poked a hole in the diaphragm on the
fuel pump, so after he figured that out and patched it the
engine ran fine and didn't use so much fuel (it had been
leaking out of that hole). We tested for radio interference
by running the engine at various throttle settings
with the transmitter antenna collapsed and walking away from
the airplane, there were no noticeable glitches. There was
no way that we could have flown it today because of the wind
here at Homer's Happy Hog Farm, but at least it's ready to
go for tomorrow.
3/19/99
We
flew it this morning and the engine worked fine and there
was no radio interference. We tested top speed with a stop
watch by making two passes up-wind and two passes down-wind,
then averaging them. Climb rate was measured with a
protractor, trigonometry and a stop watch (not exactly
scientific, but it gives us good estimates). The specs page
has been updated.
Rockets!
I
am working on the ignition system for launching Estes
rockets from the wing tips of the Weed Wacker. I just got
done building the rocket, and the control box. All that is
left is to make wing tip rails and hook-up a servo with a
micro switch. The control box has the radio switch, the
rocket arming switch, a 9-volt battery, and a light that
tells you if there is a good connection to the rocket
igniter.
I
have added a link on our links page to a site that
shows you how to make a launching system for bottle rockets.
7-3-99
We
have been having trouble with various parts of the airplane
lately. As soon as we get one thing fixed, another problem
will arise. The first problem began about a month ago and it
was a broken diaphragm in the carburetor. After waiting a
while for the parts to come, we put the carb back together
and cleaned the engine up. When we took it out to fly, we
experienced more difficulty than usual starting the engine,
but we eventually did get it going and flew it for a while.
The next time we wanted to fly, we couldn't get the engine
to fire at all, so we took the spark plug out and noticed
that there was no spark at all. After a few days, we took
the engine off and Sam took a look at the ignition system
and found that the gap in the point was too big (worn from
use). It was a good thing that it could be fixed without any
parts because it would not be likely that we could find
parts for the ignition on a 20 year old engine. After that
was fixed, the engine started much easier and had a lot more
power than before, but that was not the end of our troubles.
On the first flight after the ignition was fixed, I was
testing engine performance and gave it full throttle and
flew it at high speed past the flight line, but as it zoomed
by we heard a strange buzzing sound and a few seconds later
the tail began to shake violently. I immediately chopped the
throttle and circled to a landing. What had happened was the
control cables had become loose and introduced about 2
inches of free-play in the elevators, the result of this was
really nasty tail flutter. After we inspected it, I fixed
the sloppy cables and glued the clevises in place. On the
next flight every thing went fine until the fin became
loose, I landed it right away and we checked it out,
apparently the fin's glue joints were damaged in the
previous flight. As of now the Weed Wacker is grounded until
someone gets enough ambition to glue the fin back on.
7/22/99
Today
We installed and tested our rocket launching system. We
decided to mount the rocket on the top of the fuselage and
used the control system that I built earlier. The first
launch was a success except that we lost the nose section of
the rocket. On the second launch, we used a home-made nose
cone and no parachute. We ended up losing the rocket in the
corn.
7/23/99
We
went to the hobby store and bought $65 worth of rocket
supplies, then stopped by Radio Shack to blow $25 on
switches and stuff. After we got home at about 8:30 P.M., we
proceeded to build 3 rockets.
7/24/99
Today
we built a JATO (jet assisted takeoff) system and
added electronics and hardware to launch two more rockets
in-flight. The JATO system consists of a launch controller,
an engine holder and six estes D12-7 rocket engines. The
total maximum thrust will be about 36 pounds, and when added
to the thrust of the prop engine will come out to be about
56 pounds. The thrust to weight ratio will momentarily
exceed 1:1. The cost of the JATO burn will be $7.00 per
second ($14 for 2 seconds).
The
three rockets and the JATO are controlled by a separate
radio. We can check all connections in the ignition system
before launch one-by-one by putting the controller in test
mode and running the controls on the radio. If the
connection is good, a light will shine on the top of the
plane while it's respective radio control is activated.
We
hope to test all of this junk tomorrow.
7/25/99
Today
we tried to launch the stuff, but we forgot to arm the
rockets and I crashed while trying to land it. We will try
again soon though.
5/15/2003 The
Weed Wacker was destroyed today
after a huge explosion caused the plane to break
apart. What remained after the initial explosion was
quickly finished off by a secondary explosion and the
subsequent fireball which was caused by the onboard
fuel. There will be no more updates on the Weed
Wacker.
<<Back
|
