Website visitor Steve S. asked for a scan of Phil Kraft's Dragon-Fli pattern
plane. It appeared in the January 1971 American Aircraft Modeler on page
19. Precision / advanced aerobatics airplanes have undergone a significant
transmogrification from somewhat boxy outlines with only slightly larger
than normal control surfaces and retractable, tricycle gear, to curvaceous
tail draggers with fixed gear. Programmable radio with multiple throw rates
and control mixing have permitted a lot of freedom in the configuration
of the entire aircraft.
By Phil Kraft
All-out competition stunt ship by Phil Kraft - based on years of experience
and testing. Retracts recommended for best performance.
PATTERN FLYING TODAY is perhaps 97 per cent pilot and three per cent
aircraft design. However, the world's top fliers are so close in ability
that the airplane's three per cent can be decisive. There is no question
that in the last two years a trend has developed toward heavier, faster
competition stunt models. After all, a stunt performance is primarily intended
to take maximum advantage of the human factor in judging. At contests, fliers
often comment that "so and so" put in a lousy flight, but his spectacular
performance biased the judges.
Author holds latest in his Fli series. It is sensitive, precise, fast
Editor's note: Dragon FIi's speed and airfoils need only small control
surface movements, proper balance. It can land quite slowly, too.
In my opinion, it is not possible to differentiate between the spectacular
performance and a properly performed sequence of maneuvers. Fliers are trying
to paint a picture and to create an effect. Thus, I have come to believe
that the high-speed spectacular pattern with large graceful maneuvers will
be most effective in gaining maximum points.
This new line of thinking has been a complete turnabout. The Kwik-Fli
series of designs was in exact opposition to the current trend. They were
slower flying, lightweight, rather unspectacular designs. The maneuvers
were compact and had to be tightly controlled to be effective. The Kwik-Fli
emphasized reliability and consistency above other factors. However, it
was designed in an era when powerful contest engines which also were reliable
just weren't available. Today, there are several extremely powerful engines
with great reliability as well. Therefore, the design trend has been made
possible almost entirely by the availability of superior engines.
The Dragon Fli design is a development of the Slik-Fli-type fuselage,
combined with a newer wing design. Three different airfoils were tried during
testing before settling on a 15 per cent section with a maximum camber at
about 40 per cent. This low aspect ratio was selected primarily for ease
of transportation. It does not appear to have any deficiencies, and may
have advantages as far as flight performance is concerned. The deep fuselage
of the Dragon Fli contributes to stability, particularly in rough air. Like
anything else, it also has disadvantages, such as in taxiing in strong winds.
The plans show retract gear, and there is no question but what this is
an absolute necessity for contest flying today. Fliers used to think the
effect of retract gear was primarily psychological. However after having
flown an airplane with retract gear, I don't think I would enjoy going back
to the fixed gear model again, despite the headaches with the less than
satisfactory retract gear units that are currently available.
up, the Dragon Fli is a sound design capable of competition performance.
Jim Edwards flew one to second place in this year's Nationals, and two others
placed in the top 20 qualifiers.
Dragon Fli Plans
<click for larger version>
The AMA Plans Service offers a
full-size version of many of the plans show here at a very reasonable cost. They
will scale the plans any size for you. It is always best to buy printed plans because
my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the
Academy of Model Aeronautics - the #1
advocate for model aviation throughout the world. If the AMA no longer has this
plan on file, I will be glad to send you my higher resolution version.
Try my Scale Calculator for
Model Airplane Plans.
Posted February 11, 2011