24th F3A World Championships Technical Report
The 2005 World Championships of F3A has once again come to a close, technically
these Championships did not have the surge of new equipment and planes that we
saw happen at the previous Worlds in Poland. There were a number of improvements
to yesterday’s technology mostly surrounding electric powered models. Due to the
organization of the rounds in both the preliminaries and semi-finals I was only
able to witness approximately 30% of the total competitors. Unfortunately this
precluded me from gathering data regarding the usage of equipment by
competitors.
From rough estimation the number of flyers using electric models was much lower
than I was expecting. I would say not more than 25-30% of the competitors (112
total) were using electric models, of those the majority placed in the top 30,
the Canadians were the only complete team running electric aircraft. In my
discussions with other pilots the overwhelming reason why they had not tried
electric was due to the cost and questionable reliability of the Li-Po battery
technology, in some cases limited availability of quality cells as well.
Electric Motors
Once again Hacker completely dominated as the motor of choice. There were a
number of variations used, C50 13XL, C50 14XL, C50 13L. As well a new motor the
C50 14XL Comp was being used by a few notables, which boasts an internal cooling
fan and supposedly more power, although I got the impression that this motor was
not a significant improvement over the current 14XL motor and with a $200 US
increase in price not likely worth the extra investment.
Plettenberg made its debut into the Worlds this year and was the motor which we
ran as a team. These motors are known as outrunner type motors similar to the
Axi motors that many use in their indoor models. The Xtra 25-13 was ran by Adam
and Dez, I used the Xtra 30-10 and Bernd Berschorner from Germany used a new
motor the Xtra 30-8 that runs a smaller prop but at higher rpm for a more glow
airplane presentation. I spent a number of hours speaking with the owner Uwe
Plettenberg and gave them the propeller I was using for the 30-10 motor (APC-E
21x13W). I hope to have a new motor to test out for next year that will be even
more powerful. The Hacker setup does produce about 10-15% more power than the
Plett 30-10 setup does, but comes at the price of gearbox maintenance and a
louder running setup.
Lithium Polymer Batteries
No surprise that all of the electric powered models were using Lipo batteries.
NiCd and NiMH technology are simply too heavy to get the required power within
our weight limits. Again no surprise that Thunder Power dominated as the battery
of choice with virtually all the competitors running the 10s4p 5300 mAh F3A
packs (x2 5s packs in series). These batteries are very light and capable of
delivering up to 70A continuously which is the upper limit of where our models
run at.
A few other pilots were running custom built packs of unknown type and cell
count and seemed to have a solid power system throughout the event.
Cycle life which is the area of biggest concern is improving. I talked to a few
friends who were also running the TP 5300 packs and had around 100 cycles on
their batteries without noticeable performance decrease. I personally flew packs
with about 50 cycles on them during the event. Last years Li-Po technology would
be lucky to last 25-30 cycles in this environment so this is a major improvement
in a single year.
Electronic Speed Controls (ESC’s)
There is only one simple change worth mentioning surrounding the ESC’s that
was new. This is the addition of a proportional brake (now commonly called an
F3A brake) to the controllers. Essentially it is identical to the brakes used on
RC cars and works by initiating a brake at approximately 5% throttle and
increasing braking power to 100% at 0% throttle position. This allows the pilot
to control the downline speed with incredible precision. This is a big problem
for electric motors as without the brake there is nothing to prevent wind
milling on downlines. I managed to trade controllers with a friend and and have
since tried out the downline break. It is a major improvement to the system and
gives very good control of downline speed in all areas of the flight. It does
take a bit of getting used to as it becomes important to now fly the throttle as
idle as well which is something that most are not used to doing.
Glow Engines
YS continued its domination of the glow motors, they introduced yet another
prototype motor while many are still waiting to or just got their hands on the
current “latest and greatest” 160 DZ. The newest beast is the 170 DZ which
powered a select few airplanes at these worlds. Prop of choice was the 17x12 ran
with the air restrictor in place, unfortunately I did not gather RPM numbers
from those using it. Power was impressive and on par with the most powerful of
the electric models which typically show the most vertical authority. I felt the
engine had a deep mellow tone in the air and sounded quieter than the 140/160 DZ
motors. Time will tell if YS decides to release this engine to the public
anytime soon, news of this was extremely secret and most did not know the engine
existed until they arrived at the Worlds. No surprise as YS would not want to
hurt sales of the 160 DZ which was only released nine months ago.
Aircraft
Chip Hyde and Onda Tetsu both used biplanes that were updates from the bipes
they flew in Poland two years ago. Onda’s bipe sported a blast from the past
anhedral stab! Those from back in the day would remember this from the Curare
and Tipo aircraft. Christophe and his brother Benoit were running small wings
above the fuse at the back of the wing that they claimed to clean up the flow
over the top of the fuse and improve the flying characteristics in a number of
areas.
I was quite intrigued by this little device and managed to trace it so I can try
it myself.
The sequences are not changing significantly enough to warrant major aircraft
design changes, much of the change with current models is in the airfoils of the
wing typically to try and improve flying in adverse weather conditions.
Summary
Overall I feel that electric power was the big tech news at these Worlds. With a
fair number of people flying it and many more than that very curious about it. I
personally answered many questions about electrics from other competitors and
feel that we are at a point in F3A where a major culture change is about to
happen as people move over to electric power. It would not surprise me in the
least if at the next WC we see a significant majority flying electric powered
models.
I know many of the manufacturers were present and listening to the ideas of
those using their equipment; all these ideas should generate a major improvement
and direction change to the power systems to make them even better and more
reliable than they are today.
Please feel free to email me with questions or comments!
chad@f3acanada.org
Chad Northeast
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