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| R&D B Division Prizes
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A Boost Glide
For NARAM-46, the Boost Glide event is for A engine class.
Boost Glide
combines the challenge of building and flying a glider which can boost
relatively well (and hold together) on rocket power, and transition to a long
gliding flight.
Boost Gliders often use a pop-pod, or sometimes are
attached to the side of a larger rocket (parasite) for the vertical boost
portion of the flight, then separate for the glide back to earth. If the entry
kicks out an engine, the engine needs to have a streamer on it. A free-falling
engine casing will be DQ'ed. The glider portion is timed. The glider must be
returned for one of the two flights allowed.
Flex-wing (Rogallo/hang glider) type gliders are not
allowed.
For the full rules for this event, please see
the Boost Glide Rules
on the NAR web page.
Scoring -
For Boost Glide, the scoring is the sum of the times from the two flights
allowed, with at least one of those flights having the glider returned.
Design considerations - Trade-offs of high glider performance, visibility,
surviving rocket boost, and shooting for a reasonable boost altitude.
It's not very practical to modify the proverbial 49
cent balsa glider to fly this event since the wings probably would rip off.
Best to go with a kit such as those below, or a plan. With experience, you
might later develop a knack for designing your own gliders, but it's best to
learn from a proven design first.
A list of plans and kits is
included further down on this page.
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Pop-Pods - Nearly
all B/G's use pop-pods. These are short finless bodies that have the engine,
launch lugs, and usually a streamer for recovery. They attach to the glider
using some sort of hook system, so they carry the glider up during boost then
at ejection kick backwards to separate from the glider. Spooler Pop-Pods - Sometimes, the shock cord or streamer
on a pop-pod gets hung up on the glider, causing a tangled "Red
Baron" descent to the ground. The "Spooler" pop-pod design
eliminates shock cords, and delays streamer deployment until the pod has left
the glider. It works by having the streamer rolled up (spooled) inside so it
cannot deploy until after the nose section has been ejected off (the nose
tumbling down safely, usually painted a fluorescent color to aid in finding
it). Click here for a drawing that
shows the Spooler pod design for 13mm engines. Pod hooks
- Various kits and plans show different types of pod hook or pod attachment
methods. Unless the glider is somewhat unique, you can usually use your
favorite pod hook method on any given boost glider plan as long as you
maintain the pylon height between the top of the fuselage and the pod tube
(on most gliders, the pylon height is 1/2"). CMR Manta Hooks - The old CMR Manta kit used a hook system
that proved to be simple and mostly universal. It is easily duplicated by
using spruce for the hooks and thin plywood or G10 fiberglass sheet for the
side plates. Click here
for a drawing showing more details than at right. Apogee Universal Glider Hooks - A single cast part
design which has a hook and a slot, which fits with an identical cast hook
and slot part (see drawing at right). One is glued to the pod, and one is
glued to the glider (these were originally developed for the Maxima glider
kits). Any glider can fit any pod, since the hooks are all identical. Click here for a drawing
showing more details than at right. The hooks are sold
by Apogee. |
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Building Gliders
- Ed LaCroix created some fantastic instructions
for the Maxima A Boost Glider kit, from the time when Ed owned and
ran Apogee. The kits are gone now, but the plans and instructions live on (a
nearly 1 meg pdf file, well worth the download). The instructions are so
in-depth that they are a must-read for anyone wanting to learn more on
how to build, trim, and fly rocket boosted gliders of any kind. And the Maxima
A also is a good contest model. Click
here for a GIF file showing the wing and tail templates more
clearly, and to exact size.
Kevin Wickart wrote a nice short article on how to do
quick and easy airfoils, on the WOOSH section's website. Click
here to read it.
A VERY nice sanding block, useful for gliders,
helicopters, and any rocket really, is an all-metal 2-piece clamp-type sanding
block made by Red Devil, carried by most Ace Hardware stores (look near where
they stock sandpaper). It has a 1/8" foam rubber backing sheet, which
should be removed since it allows rounding things too easily in 3-D when you
usually want to shape in 2-D at a given time (as with a wing). So, remove the
rubberized portion. That sanding block holds a 4.5 x 5.5" sheet of
sandpaper (quarter of a 9 x 11" sheet), with a 3.5 x 4.5" sanding
surface area on the block. This works far better in most cases than a narrow
sanding block. Of course, the wings (or fins) should be shaped and finished
before they are glued to the fuselage or model.
When doing very rough shaping for wings, 80 to 120
grit sandpaper is good for grinding off a lot of wood in a short time. Don't
over-do it though by sanding off too much. Next use a finer grit like 180 to
220 for finer shaping. Beyond that, 280/320 paper, is sort of a cross between
final shaping and setting up for a final finish. A final finish for bare balsa
is sanding with 400 grit paper. Get the "black" type wet or dry
sandpaper, it sands better and lasts longer than the reddish types. If you use
any clear dope, use 320 to 400 grit paper before and after.
Glider Finish
- Never use paint on a contest type glider. For newer fliers, no finish is
usually fine. You don 't want to weigh the model down too much and maybe having
warpage problems. If you want to improve the finish, use some thinned clear
dope in one or two light coats, sanding before and after with 240 and 400 grit sandpaper.
The idea it not to add weight or cause the wood parts to warp. Some fliers like
to use a Japanese tissue finish, but that is more for experts and to an extent
is overkill for A B/G's.
Coloring -
OK, so bare balsa (even with clear dope) is not easy to see in the air or on
the ground. Use a large black magic marker to color the bottom of the wing and
tail surfaces black, as black shows up against the sky pretty well. Use a large
red or orange magic marker to color the top surfaces. If you can find true
fluorescent markers (not to be confused with wimpy fluorescent highlighters),
an orange or red/magenta fluorescent color is highly recommended.
Glide trimming
- It is an understatement to say that it is very important to trim the glider
to glide properly. It's not easy to describe just how to do so.
One mostly universal tip is to have the tail of the
glider and the wing to NOT be parallel to each other (there should be slight
postitive incidence). There ought to be a little bit of "up elevator"
angle in the tail, relative to the wing, to make the nose pull up a bit. Some
plans/kits may be quite specific, and in those cases go with what they say.
Note that free flight model airplane experts sometimes prefer zero incidence,
but they are deeply experienced (usually) to have just the right touch and
experience to get away with it.
The above being said, one of the simple ways to
achieve slight positive incidence (without adding too much) is to build the
model zero-zero, then warp the trailing edge of the stabilizer up. Make sure
that the fuselage itself is not warped "down" - if it is warped at
all, better to be warped "up" relative to the wing and stabilizer.
Here are a few links for trimming tips from a number
of different sources:
Estes Boost Glider Technical Report, written
by Tom Beach (pdf file from Estes Educator website). An excellent
article with many illustrations, that cover
a wide range of areas involving Boost Gliders and Rocket Gliders, including
trimming. HIGHLY RECOMMENDED.
Kevin McKiou's Basics
of Design and Trimming of B/G's and R/G's. Items 1 thru 5 are useful
only if you are designing your own, or modifying an existing plan/kit. Items 6
thru 9 are useful for trimming gliders for optimum glide performance.
Again, Ed LaCroix's instructions
for the Maxima A Boost Glider has trimming tips.
Hand
Launch Glider trimming tips for beginners, from a British Free
Flight model airplane site. The latter portions about hard throws (necessary
for contest HL gliders) is not too relevant for rocket boosted gliders (since
the F/F HL glider flyers's hard upward throws are their equivalents to our
rocket "boosts"). Note the basic glide trim info and illustrations at
the top of the page.
Launching -
Set up the glider on the pad so that it faces into the wind. This means the
wing bottom faces upwind, and the wing top faces downwind. Actually the
dihedral effect will usually try to make the glider face that way.
Apply a flag of masking tape to the launch rod, so the
flag holds the pop-pod high enough for the glider tail to not be touching the
bottom of the launcher. Some people prefer to make their own glider launcher
that has the launch rod mounted onto a 3/8" or 1/2" dowel, so that
the whole rod can be used for guidance.
A classic launch problem is for the micro-clips to
fall at ignition to grab onto the glider wing or tail, causing damage or even
disaster. Some prefer to tape the clips to the rod so they can't fall, which is
effective but a bit messy. Others like to use an umbilical approach. They
arrange for a separate launch rod, dowel, or other structure to hold the micro
clip wires away from the glider, so that when the clips fall they will not fall
straight down, but will swing away in an arc from the glider. A simple
umbilical is to use a piece of 1/4 x 1/4 spruce 18" long or so, and cut
the bottom at a very sharp angle that is about 30 degrees from vertical. Then
glue a launch lug to the angled part. That way, the spruce umbilical can be
slipped over the launch rod, umbilical angled at 30 degrees fro mthe rod, ready
for the micro-clips to be attached to it. Put your name on it, since the next
person to use that pad will probably want to remove your umbilical.
More Information:
- See
the RMR
Rocket Boosted Glider FAQ (Frequently Asked Questions). Scroll
down section 9.2 for free-flight RBG info.
- See
the "RocketBoostGliders"
Yahoogroup,which discusses Boost Gliders and Rocket Gliders.
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Engine recommendation
for A Boost Glide: |
A3-4T |
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(A slightly shorter
delay would be preferred for some larger gliders, and some old plans suggest shorter
delays. But Estes A3-2T's and Apogee micro A's have not been made for a long
time, and have lost contest certification) |
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Model Plans & Kits |
Designer |
Notes |
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Rocky
Mountain Canary II plan, (NAR website) |
Plan by Bruce Carey |
The wing should be made using 1/8" balsa, to be
strong enough for A power |
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Turnup
plan, (NAR website) |
Plan by Phil Slaymaker |
A design that has been popular in recent years |
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Plan by George Gassaway |
1/2A & A design, wing should be 1/8" for A power. |
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Deltie Boost
Glider Kit (13mm) from |
Kit designed by Rob Edmonds of Edmonds
Aerospace |
Easy to build and reliable kit. |
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Ivee2G Boost
Glider Kit (13mm) from |
Kit by Rob Edmonds of Edmonds
Aerospace |
Basic competition-style boost-glider. Not currently
on |
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QCR - "Neverloop"
B/G kit series by Ken Brown |
Kits by Ken Brown - QCR - Qualified
Competition Rockets |
Various B/G's designed for contest flying. See QCR's
website. |
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Maxima
A B/G plan (former Apogee kit) |
Basic design by George Gassaway, refined and with
great instructions by Ed LaCroix. |
Competitive plan, plus detailed info on
building/flying B/G's. Also get the wing
and tail templates |
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