November 2003 93
THIS MONTH I’LL give you some details
and flight impressions of three new gliders.
The Spinner is an inexpensive expanded
polypropylene (EPP)-foam discus-launch
glider (DLG) kit, the Hyper DL is an
inexpensive Almost Ready-to-Fly (ARF)
DLG, and the AVA is an ultralight ARF that
looks like Mark Drela’s Bubble Dancer.
The high-end DLGs reached maturity last
year. In other words, last year’s versions of
the XP-3, the Taboo, and the Encore are still
competitive this year. Although the contestdriven
designs have stabilized, there is still a
great deal of improvement to be made in
cost reduction and durability.
The $300-$450 DLGs are very durable.
Most of the less-expensive versions are
fragile in comparison. It is common to see
$250 imported DLGs break on the first day.
I have been hoping to find a tough, low-cost
model that I can recommend for a first
discus glider.
Ed Berg of Englewood, Colorado,
designed the Spinner. The instructions read:
“The Spinner was designed to fill the
need for a plane that could be discuslaunched
and flown in a wide range of
conditions, and survive crash landings in
rough terrain. It had to be easy to fly, easy
to build, hard to break, and easy to repair.”
Mike Garton, 2733 NE 95th Ave., Ankeny IA 50021; E-mail: [email protected]
RADIO CONTROL SOARING
The Spinner is a new durable discus-launch trainer/sport glider. The expanded
polypropylene (EPP)-foam wings and fuselage pod cushion impacts.
Spinner uses Drela airfoils and large flaperons, which gives it a wide speed range.
The Spinner kit contains wood tail parts, EPP wings, an EPP fuselage pod, four carbon
wing spars, a carbon tailboom, and complete hardware.
AVA uses composites to make “lighter than
built up” floater. You won’t find other 126-
inch-span gliders weighing 38 ounces.
94 MODEL AVIATION
Ed let me fly one of the prototypes. The
Spinner is cheap, strong, and fun to fly. It
has straight-taper wings with the AG-44
airfoil at the root and the AG-46 airfoil at
the tip. The conservative planform gives
friendly handling with no tip stall. The
Mark Drela airfoils give it a good glide
ratio and a wide speed range.
The wing construction is EPP-foam
cores with a carbon-tube spar and carbontube
sub-trailing edge. The wood supplied
in the kit for the flaperons was custommachined
to match the airfoil’s thickness.
Fiberglass strapping tape reinforces the EPP
foam, and Oracover is recommended for
covering.
The Spinner’s nominal weight is 15
ounces, which makes its sink rate higher
than the competition DLGs. On the other
hand, this may be the only discus glider
available that is inexpensive—$125—and
durable.
The Spinner kit is complete except for
glue, tape, and covering, and it comes with
a 12-page instruction manual. The EPPfoam
fuselage pod is preshaped in top and
side profiles. Most of the wood in the kit is
laser-cut. An experienced builder could
complete a Spinner in approximately 15
hours plus glue drying time.
The Spinner’s EPP wing and fuselage
pod can take a great deal of abuse. I watched
Ed crash hard enough to shear both nylon
wing bolts. He was playing around inverted
and waited too long to loop out. He dug out
the old bolts, put in new ones, and continued
flying.
The flexible wing construction does have
a downside; advanced throwers will be able
to flutter it with high-power launches. Ed
was throwing his Spinner to 80 or 90 feet
with no flutter. I usually throw my XP-3 to
roughly 140 feet. With a full launch, I did
make the Spinner flutter its wings. Ed said I
was the first to do that. I do not hold it
against the design.
The Spinner is a good option for a first
DLG, rough-terrain aerobatic Sloper, or
sport flier of any type. There is a big niche
in the market for an inexpensive DLG that
can last through a flying season. The
Spinner may be alone in that slot.
The Hyper DL (HDL) is an ARF glider
from Art Hobby. It is also inexpensive, at
$131 as I write this. The HDL has straighttaper
wings with the HN1033 airfoil thinned
to 8%. It uses four servos and has partialspan
ailerons. Flying weight is 14-15
ounces.
The HDL’s fuselage pod is white gelcoated
fiberglass. A canopy hatch provides
access to the nose. The pod is small and
sexy, but it’s difficult to install gear in. The
carbon tailboom is larger than the common
kite spars. Tail surfaces are solid balsa sheet.
The HDL wings are white foam with
black poplar-veneer wing skins. The poplar
is bonded to the cores while it’s pressed into
female wing molds. This method produces a
tough and accurate wing. I was impressed
with the amount of prefabrication in a kit
with this low of a cost.
I helped a friend test-fly his HDL. It
started out built stock. My first impression
was that it was heavy and fast, with no flaps
to slow it down. Compared to a flaperon
DLG, it lands like a jet on ice.
The HDL’s wingtips taper toward the
trailing edge at almost a 45° angle. These
swept Sagitta-style tips are not a good
choice for a DLG. The recommended peg
location is near the high point of the airfoil.
With each throw, the raked-back wingtip
hurt my hand as it hit the web between my
fingers. The hand strikes can be avoided by
making a more squared-off wingtip or
moving the peg to the trailing-edge tip. The
former is preferable.
I blew the wing off on one of the first
moderate-power launches. It had been held
on with one wire pin at the leading edge and
one nylon bolt near the trailing edge. The
fuselage pod gained some cracks in the
crash. After that incident we removed the
wire wing pin and added a second nylon
bolt. Later we cracked the balsa rudder with
air loads on launch. More fiberglass took
care of that. High-dollar DLGs come with
fiberglassed wooden tail surfaces.
Even with a gyro, the yaw oscillations on
launch are a little larger than on most DLGs.
This is because the relatively heavy
hardwood-sheeted wing creates more inertia
in the yaw axis. More vertical fin height
should help.
Built with the stock nearly-flat wing,
thermal turns required constant attention. If I
stopped actively controlling the model for
three seconds, it would be in a vertical dive.
A visit to the table saw and adding 6° of
dihedral per side fixed that problem. It did
require us to make a new saddle for the wing
using a bit of epoxy and cabosil filler.
Handling is much improved with the
higher dihedral. It is still difficult to get a
good thermal climb rate out of the glider.
The weight and lack of camber control force
a pilot to make large, fast circles compared
to flaperon-equipped gliders.
A redeeming quality of the Hyper DL is
the availability of (inexpensive!)
replacement parts. A new fuselage with pod
and boom is $46. Wings are $70.
I called Andre of Art Hobby and gave
him some feedback from my experience:
two bolts for the wing, flaperons, 6°-perside
dihedral, square off the wing, and more
vertical fin. Builders may also want to
fiberglass the vertical fin and rudder.
Replacing the pushrod system and not using
metal tail fasteners will reduce the need for
nose weight.
Hopefully many of the changes will
make it into production by the time you read
this. If they don’t, they are easy for the
builder to make. With the tweaks I listed,
the Hyper DL is still a good value.
The AVA is imported from Ukraine and is
made by Vladimir, maker of the graphite
and organic. As this is being written, it is
available exclusively from Barry Kennedy.
The AVA is unusual in that high-tech
materials and methods were used to make a
rudder-controlled floater. The aerodynamics
design is a direct knockoff of Mark Drela’s
Bubble Dancer. The 127-inch-wingspan
AVA weighs approximately 38 ounces
ready to fly. With 1,100 square inches of
wing area, the wing loading is just less than
5 ounces per square foot.
A detail photo of a radio installation in Jim Porter’s AVA. Notice
the unusual pushrod support. Text contains details.
The Hyper DL from Art Hobby is another inexpensive discuslaunch
glider. Text offers many suggested modifications.
Continued on page 114
RC Soaring
The AVA has a 36-inch-wide single
carbon spoiler across the center-section.
The three-piece wing is carbon/Kevlar Dbox,
Kevlar-wrapped spar, carbon-capped
ribs, and carbon trailing edge, all wrapped
in Oracover. The leading edge,
carbon/Kevlar on a 45 bias, D-box is also
made in a mold. The fuselage has a slideon
nose cone, and all are prepainted in a
mold then postcured.
The AVA is $705 shipped. Kevlar
ballast tubes are available for $10 each.
The ballast tube mounts in the fuselage
and holds 14-18 ounces. The sailplanes
are shipped in returnable Series 3 Sport
Tubes.
The generous three-panel-per-side
polyhedral makes for beautiful thermal
turns. Although the handling is
extremely good, nothing happens
quickly because of the slow
(unballasted) speed. Jim Porter had not
tried his AVA’s towhook yet because
“you don’t need to.” A firm toss was
enough launch to catch thermals each
time he went out.
Jim positioned his servos at the front
of the compartment to minimize nose
weight. In the end he found that he
needed 1⁄2 ounce of weight at the tip of
the tail. In hindsight, they should have
been put rearward.
A pushrod trick is visible in the
detail photo of Jim Porter’s AVA.
Putting the servos forward left them
potentially unsupported for 4 or 5
inches. To solve this problem, Jim
drilled a small hole in the servo tray
directly under the pushrod. Then he
pushed a small carbon rod into the hole.
The carbon rod should be long
enough to extend from the floor of the
fuselage through the pushrod tray and
up to the pushrod. It is glued to the
fuselage floor and to the servo tray,
then a small piece of pushrod housing
tube is fit over the pushrod and aligned
over the carbon rod. Thread or string is
used to lash the pushrod housing piece
onto the carbon rod. Some CyA
(cyanoacrylate) glue is used to harden
the thread. The support is light and
strong.
You may also notice a pushrod
splice exposed in Jim’s AVA; 48-inch
carbon pushrods were not quite long
enough for the forward servo position
he chose. Spare nylon tail bolts are also
visible, screwed in between the servos
and the switch. MA
Sources:
Spinner:
Ed Berg
(303) 762-9085
[email protected]
http://upslopesoaring.com/
Hyper DL:
Art Hobby
(406) 256-1224
www.arthobby.com
AVA:
Barry Kennedy
(972) 602-3144
[email protected]
http://kennedycomposites.com
Edition: Model Aviation - 2003/11
Page Numbers: 93,94,114
Edition: Model Aviation - 2003/11
Page Numbers: 93,94,114
November 2003 93
THIS MONTH I’LL give you some details
and flight impressions of three new gliders.
The Spinner is an inexpensive expanded
polypropylene (EPP)-foam discus-launch
glider (DLG) kit, the Hyper DL is an
inexpensive Almost Ready-to-Fly (ARF)
DLG, and the AVA is an ultralight ARF that
looks like Mark Drela’s Bubble Dancer.
The high-end DLGs reached maturity last
year. In other words, last year’s versions of
the XP-3, the Taboo, and the Encore are still
competitive this year. Although the contestdriven
designs have stabilized, there is still a
great deal of improvement to be made in
cost reduction and durability.
The $300-$450 DLGs are very durable.
Most of the less-expensive versions are
fragile in comparison. It is common to see
$250 imported DLGs break on the first day.
I have been hoping to find a tough, low-cost
model that I can recommend for a first
discus glider.
Ed Berg of Englewood, Colorado,
designed the Spinner. The instructions read:
“The Spinner was designed to fill the
need for a plane that could be discuslaunched
and flown in a wide range of
conditions, and survive crash landings in
rough terrain. It had to be easy to fly, easy
to build, hard to break, and easy to repair.”
Mike Garton, 2733 NE 95th Ave., Ankeny IA 50021; E-mail: [email protected]
RADIO CONTROL SOARING
The Spinner is a new durable discus-launch trainer/sport glider. The expanded
polypropylene (EPP)-foam wings and fuselage pod cushion impacts.
Spinner uses Drela airfoils and large flaperons, which gives it a wide speed range.
The Spinner kit contains wood tail parts, EPP wings, an EPP fuselage pod, four carbon
wing spars, a carbon tailboom, and complete hardware.
AVA uses composites to make “lighter than
built up” floater. You won’t find other 126-
inch-span gliders weighing 38 ounces.
94 MODEL AVIATION
Ed let me fly one of the prototypes. The
Spinner is cheap, strong, and fun to fly. It
has straight-taper wings with the AG-44
airfoil at the root and the AG-46 airfoil at
the tip. The conservative planform gives
friendly handling with no tip stall. The
Mark Drela airfoils give it a good glide
ratio and a wide speed range.
The wing construction is EPP-foam
cores with a carbon-tube spar and carbontube
sub-trailing edge. The wood supplied
in the kit for the flaperons was custommachined
to match the airfoil’s thickness.
Fiberglass strapping tape reinforces the EPP
foam, and Oracover is recommended for
covering.
The Spinner’s nominal weight is 15
ounces, which makes its sink rate higher
than the competition DLGs. On the other
hand, this may be the only discus glider
available that is inexpensive—$125—and
durable.
The Spinner kit is complete except for
glue, tape, and covering, and it comes with
a 12-page instruction manual. The EPPfoam
fuselage pod is preshaped in top and
side profiles. Most of the wood in the kit is
laser-cut. An experienced builder could
complete a Spinner in approximately 15
hours plus glue drying time.
The Spinner’s EPP wing and fuselage
pod can take a great deal of abuse. I watched
Ed crash hard enough to shear both nylon
wing bolts. He was playing around inverted
and waited too long to loop out. He dug out
the old bolts, put in new ones, and continued
flying.
The flexible wing construction does have
a downside; advanced throwers will be able
to flutter it with high-power launches. Ed
was throwing his Spinner to 80 or 90 feet
with no flutter. I usually throw my XP-3 to
roughly 140 feet. With a full launch, I did
make the Spinner flutter its wings. Ed said I
was the first to do that. I do not hold it
against the design.
The Spinner is a good option for a first
DLG, rough-terrain aerobatic Sloper, or
sport flier of any type. There is a big niche
in the market for an inexpensive DLG that
can last through a flying season. The
Spinner may be alone in that slot.
The Hyper DL (HDL) is an ARF glider
from Art Hobby. It is also inexpensive, at
$131 as I write this. The HDL has straighttaper
wings with the HN1033 airfoil thinned
to 8%. It uses four servos and has partialspan
ailerons. Flying weight is 14-15
ounces.
The HDL’s fuselage pod is white gelcoated
fiberglass. A canopy hatch provides
access to the nose. The pod is small and
sexy, but it’s difficult to install gear in. The
carbon tailboom is larger than the common
kite spars. Tail surfaces are solid balsa sheet.
The HDL wings are white foam with
black poplar-veneer wing skins. The poplar
is bonded to the cores while it’s pressed into
female wing molds. This method produces a
tough and accurate wing. I was impressed
with the amount of prefabrication in a kit
with this low of a cost.
I helped a friend test-fly his HDL. It
started out built stock. My first impression
was that it was heavy and fast, with no flaps
to slow it down. Compared to a flaperon
DLG, it lands like a jet on ice.
The HDL’s wingtips taper toward the
trailing edge at almost a 45° angle. These
swept Sagitta-style tips are not a good
choice for a DLG. The recommended peg
location is near the high point of the airfoil.
With each throw, the raked-back wingtip
hurt my hand as it hit the web between my
fingers. The hand strikes can be avoided by
making a more squared-off wingtip or
moving the peg to the trailing-edge tip. The
former is preferable.
I blew the wing off on one of the first
moderate-power launches. It had been held
on with one wire pin at the leading edge and
one nylon bolt near the trailing edge. The
fuselage pod gained some cracks in the
crash. After that incident we removed the
wire wing pin and added a second nylon
bolt. Later we cracked the balsa rudder with
air loads on launch. More fiberglass took
care of that. High-dollar DLGs come with
fiberglassed wooden tail surfaces.
Even with a gyro, the yaw oscillations on
launch are a little larger than on most DLGs.
This is because the relatively heavy
hardwood-sheeted wing creates more inertia
in the yaw axis. More vertical fin height
should help.
Built with the stock nearly-flat wing,
thermal turns required constant attention. If I
stopped actively controlling the model for
three seconds, it would be in a vertical dive.
A visit to the table saw and adding 6° of
dihedral per side fixed that problem. It did
require us to make a new saddle for the wing
using a bit of epoxy and cabosil filler.
Handling is much improved with the
higher dihedral. It is still difficult to get a
good thermal climb rate out of the glider.
The weight and lack of camber control force
a pilot to make large, fast circles compared
to flaperon-equipped gliders.
A redeeming quality of the Hyper DL is
the availability of (inexpensive!)
replacement parts. A new fuselage with pod
and boom is $46. Wings are $70.
I called Andre of Art Hobby and gave
him some feedback from my experience:
two bolts for the wing, flaperons, 6°-perside
dihedral, square off the wing, and more
vertical fin. Builders may also want to
fiberglass the vertical fin and rudder.
Replacing the pushrod system and not using
metal tail fasteners will reduce the need for
nose weight.
Hopefully many of the changes will
make it into production by the time you read
this. If they don’t, they are easy for the
builder to make. With the tweaks I listed,
the Hyper DL is still a good value.
The AVA is imported from Ukraine and is
made by Vladimir, maker of the graphite
and organic. As this is being written, it is
available exclusively from Barry Kennedy.
The AVA is unusual in that high-tech
materials and methods were used to make a
rudder-controlled floater. The aerodynamics
design is a direct knockoff of Mark Drela’s
Bubble Dancer. The 127-inch-wingspan
AVA weighs approximately 38 ounces
ready to fly. With 1,100 square inches of
wing area, the wing loading is just less than
5 ounces per square foot.
A detail photo of a radio installation in Jim Porter’s AVA. Notice
the unusual pushrod support. Text contains details.
The Hyper DL from Art Hobby is another inexpensive discuslaunch
glider. Text offers many suggested modifications.
Continued on page 114
RC Soaring
The AVA has a 36-inch-wide single
carbon spoiler across the center-section.
The three-piece wing is carbon/Kevlar Dbox,
Kevlar-wrapped spar, carbon-capped
ribs, and carbon trailing edge, all wrapped
in Oracover. The leading edge,
carbon/Kevlar on a 45 bias, D-box is also
made in a mold. The fuselage has a slideon
nose cone, and all are prepainted in a
mold then postcured.
The AVA is $705 shipped. Kevlar
ballast tubes are available for $10 each.
The ballast tube mounts in the fuselage
and holds 14-18 ounces. The sailplanes
are shipped in returnable Series 3 Sport
Tubes.
The generous three-panel-per-side
polyhedral makes for beautiful thermal
turns. Although the handling is
extremely good, nothing happens
quickly because of the slow
(unballasted) speed. Jim Porter had not
tried his AVA’s towhook yet because
“you don’t need to.” A firm toss was
enough launch to catch thermals each
time he went out.
Jim positioned his servos at the front
of the compartment to minimize nose
weight. In the end he found that he
needed 1⁄2 ounce of weight at the tip of
the tail. In hindsight, they should have
been put rearward.
A pushrod trick is visible in the
detail photo of Jim Porter’s AVA.
Putting the servos forward left them
potentially unsupported for 4 or 5
inches. To solve this problem, Jim
drilled a small hole in the servo tray
directly under the pushrod. Then he
pushed a small carbon rod into the hole.
The carbon rod should be long
enough to extend from the floor of the
fuselage through the pushrod tray and
up to the pushrod. It is glued to the
fuselage floor and to the servo tray,
then a small piece of pushrod housing
tube is fit over the pushrod and aligned
over the carbon rod. Thread or string is
used to lash the pushrod housing piece
onto the carbon rod. Some CyA
(cyanoacrylate) glue is used to harden
the thread. The support is light and
strong.
You may also notice a pushrod
splice exposed in Jim’s AVA; 48-inch
carbon pushrods were not quite long
enough for the forward servo position
he chose. Spare nylon tail bolts are also
visible, screwed in between the servos
and the switch. MA
Sources:
Spinner:
Ed Berg
(303) 762-9085
[email protected]
http://upslopesoaring.com/
Hyper DL:
Art Hobby
(406) 256-1224
www.arthobby.com
AVA:
Barry Kennedy
(972) 602-3144
[email protected]
http://kennedycomposites.com
Edition: Model Aviation - 2003/11
Page Numbers: 93,94,114
November 2003 93
THIS MONTH I’LL give you some details
and flight impressions of three new gliders.
The Spinner is an inexpensive expanded
polypropylene (EPP)-foam discus-launch
glider (DLG) kit, the Hyper DL is an
inexpensive Almost Ready-to-Fly (ARF)
DLG, and the AVA is an ultralight ARF that
looks like Mark Drela’s Bubble Dancer.
The high-end DLGs reached maturity last
year. In other words, last year’s versions of
the XP-3, the Taboo, and the Encore are still
competitive this year. Although the contestdriven
designs have stabilized, there is still a
great deal of improvement to be made in
cost reduction and durability.
The $300-$450 DLGs are very durable.
Most of the less-expensive versions are
fragile in comparison. It is common to see
$250 imported DLGs break on the first day.
I have been hoping to find a tough, low-cost
model that I can recommend for a first
discus glider.
Ed Berg of Englewood, Colorado,
designed the Spinner. The instructions read:
“The Spinner was designed to fill the
need for a plane that could be discuslaunched
and flown in a wide range of
conditions, and survive crash landings in
rough terrain. It had to be easy to fly, easy
to build, hard to break, and easy to repair.”
Mike Garton, 2733 NE 95th Ave., Ankeny IA 50021; E-mail: [email protected]
RADIO CONTROL SOARING
The Spinner is a new durable discus-launch trainer/sport glider. The expanded
polypropylene (EPP)-foam wings and fuselage pod cushion impacts.
Spinner uses Drela airfoils and large flaperons, which gives it a wide speed range.
The Spinner kit contains wood tail parts, EPP wings, an EPP fuselage pod, four carbon
wing spars, a carbon tailboom, and complete hardware.
AVA uses composites to make “lighter than
built up” floater. You won’t find other 126-
inch-span gliders weighing 38 ounces.
94 MODEL AVIATION
Ed let me fly one of the prototypes. The
Spinner is cheap, strong, and fun to fly. It
has straight-taper wings with the AG-44
airfoil at the root and the AG-46 airfoil at
the tip. The conservative planform gives
friendly handling with no tip stall. The
Mark Drela airfoils give it a good glide
ratio and a wide speed range.
The wing construction is EPP-foam
cores with a carbon-tube spar and carbontube
sub-trailing edge. The wood supplied
in the kit for the flaperons was custommachined
to match the airfoil’s thickness.
Fiberglass strapping tape reinforces the EPP
foam, and Oracover is recommended for
covering.
The Spinner’s nominal weight is 15
ounces, which makes its sink rate higher
than the competition DLGs. On the other
hand, this may be the only discus glider
available that is inexpensive—$125—and
durable.
The Spinner kit is complete except for
glue, tape, and covering, and it comes with
a 12-page instruction manual. The EPPfoam
fuselage pod is preshaped in top and
side profiles. Most of the wood in the kit is
laser-cut. An experienced builder could
complete a Spinner in approximately 15
hours plus glue drying time.
The Spinner’s EPP wing and fuselage
pod can take a great deal of abuse. I watched
Ed crash hard enough to shear both nylon
wing bolts. He was playing around inverted
and waited too long to loop out. He dug out
the old bolts, put in new ones, and continued
flying.
The flexible wing construction does have
a downside; advanced throwers will be able
to flutter it with high-power launches. Ed
was throwing his Spinner to 80 or 90 feet
with no flutter. I usually throw my XP-3 to
roughly 140 feet. With a full launch, I did
make the Spinner flutter its wings. Ed said I
was the first to do that. I do not hold it
against the design.
The Spinner is a good option for a first
DLG, rough-terrain aerobatic Sloper, or
sport flier of any type. There is a big niche
in the market for an inexpensive DLG that
can last through a flying season. The
Spinner may be alone in that slot.
The Hyper DL (HDL) is an ARF glider
from Art Hobby. It is also inexpensive, at
$131 as I write this. The HDL has straighttaper
wings with the HN1033 airfoil thinned
to 8%. It uses four servos and has partialspan
ailerons. Flying weight is 14-15
ounces.
The HDL’s fuselage pod is white gelcoated
fiberglass. A canopy hatch provides
access to the nose. The pod is small and
sexy, but it’s difficult to install gear in. The
carbon tailboom is larger than the common
kite spars. Tail surfaces are solid balsa sheet.
The HDL wings are white foam with
black poplar-veneer wing skins. The poplar
is bonded to the cores while it’s pressed into
female wing molds. This method produces a
tough and accurate wing. I was impressed
with the amount of prefabrication in a kit
with this low of a cost.
I helped a friend test-fly his HDL. It
started out built stock. My first impression
was that it was heavy and fast, with no flaps
to slow it down. Compared to a flaperon
DLG, it lands like a jet on ice.
The HDL’s wingtips taper toward the
trailing edge at almost a 45° angle. These
swept Sagitta-style tips are not a good
choice for a DLG. The recommended peg
location is near the high point of the airfoil.
With each throw, the raked-back wingtip
hurt my hand as it hit the web between my
fingers. The hand strikes can be avoided by
making a more squared-off wingtip or
moving the peg to the trailing-edge tip. The
former is preferable.
I blew the wing off on one of the first
moderate-power launches. It had been held
on with one wire pin at the leading edge and
one nylon bolt near the trailing edge. The
fuselage pod gained some cracks in the
crash. After that incident we removed the
wire wing pin and added a second nylon
bolt. Later we cracked the balsa rudder with
air loads on launch. More fiberglass took
care of that. High-dollar DLGs come with
fiberglassed wooden tail surfaces.
Even with a gyro, the yaw oscillations on
launch are a little larger than on most DLGs.
This is because the relatively heavy
hardwood-sheeted wing creates more inertia
in the yaw axis. More vertical fin height
should help.
Built with the stock nearly-flat wing,
thermal turns required constant attention. If I
stopped actively controlling the model for
three seconds, it would be in a vertical dive.
A visit to the table saw and adding 6° of
dihedral per side fixed that problem. It did
require us to make a new saddle for the wing
using a bit of epoxy and cabosil filler.
Handling is much improved with the
higher dihedral. It is still difficult to get a
good thermal climb rate out of the glider.
The weight and lack of camber control force
a pilot to make large, fast circles compared
to flaperon-equipped gliders.
A redeeming quality of the Hyper DL is
the availability of (inexpensive!)
replacement parts. A new fuselage with pod
and boom is $46. Wings are $70.
I called Andre of Art Hobby and gave
him some feedback from my experience:
two bolts for the wing, flaperons, 6°-perside
dihedral, square off the wing, and more
vertical fin. Builders may also want to
fiberglass the vertical fin and rudder.
Replacing the pushrod system and not using
metal tail fasteners will reduce the need for
nose weight.
Hopefully many of the changes will
make it into production by the time you read
this. If they don’t, they are easy for the
builder to make. With the tweaks I listed,
the Hyper DL is still a good value.
The AVA is imported from Ukraine and is
made by Vladimir, maker of the graphite
and organic. As this is being written, it is
available exclusively from Barry Kennedy.
The AVA is unusual in that high-tech
materials and methods were used to make a
rudder-controlled floater. The aerodynamics
design is a direct knockoff of Mark Drela’s
Bubble Dancer. The 127-inch-wingspan
AVA weighs approximately 38 ounces
ready to fly. With 1,100 square inches of
wing area, the wing loading is just less than
5 ounces per square foot.
A detail photo of a radio installation in Jim Porter’s AVA. Notice
the unusual pushrod support. Text contains details.
The Hyper DL from Art Hobby is another inexpensive discuslaunch
glider. Text offers many suggested modifications.
Continued on page 114
RC Soaring
The AVA has a 36-inch-wide single
carbon spoiler across the center-section.
The three-piece wing is carbon/Kevlar Dbox,
Kevlar-wrapped spar, carbon-capped
ribs, and carbon trailing edge, all wrapped
in Oracover. The leading edge,
carbon/Kevlar on a 45 bias, D-box is also
made in a mold. The fuselage has a slideon
nose cone, and all are prepainted in a
mold then postcured.
The AVA is $705 shipped. Kevlar
ballast tubes are available for $10 each.
The ballast tube mounts in the fuselage
and holds 14-18 ounces. The sailplanes
are shipped in returnable Series 3 Sport
Tubes.
The generous three-panel-per-side
polyhedral makes for beautiful thermal
turns. Although the handling is
extremely good, nothing happens
quickly because of the slow
(unballasted) speed. Jim Porter had not
tried his AVA’s towhook yet because
“you don’t need to.” A firm toss was
enough launch to catch thermals each
time he went out.
Jim positioned his servos at the front
of the compartment to minimize nose
weight. In the end he found that he
needed 1⁄2 ounce of weight at the tip of
the tail. In hindsight, they should have
been put rearward.
A pushrod trick is visible in the
detail photo of Jim Porter’s AVA.
Putting the servos forward left them
potentially unsupported for 4 or 5
inches. To solve this problem, Jim
drilled a small hole in the servo tray
directly under the pushrod. Then he
pushed a small carbon rod into the hole.
The carbon rod should be long
enough to extend from the floor of the
fuselage through the pushrod tray and
up to the pushrod. It is glued to the
fuselage floor and to the servo tray,
then a small piece of pushrod housing
tube is fit over the pushrod and aligned
over the carbon rod. Thread or string is
used to lash the pushrod housing piece
onto the carbon rod. Some CyA
(cyanoacrylate) glue is used to harden
the thread. The support is light and
strong.
You may also notice a pushrod
splice exposed in Jim’s AVA; 48-inch
carbon pushrods were not quite long
enough for the forward servo position
he chose. Spare nylon tail bolts are also
visible, screwed in between the servos
and the switch. MA
Sources:
Spinner:
Ed Berg
(303) 762-9085
[email protected]
http://upslopesoaring.com/
Hyper DL:
Art Hobby
(406) 256-1224
www.arthobby.com
AVA:
Barry Kennedy
(972) 602-3144
[email protected]
http://kennedycomposites.com
