Articles & Tips
Index > Mark Drela's Aegea 2m Glider
[Courtesy of Mark Drela, drela "at"
mit.edu, Nov 2003 - web presentation by Tomer Jackman, Jackman_Tomer "at" EMC.com]
Photos courtesy of Jeff Newcum
About the Aegea 2m Glider
Construction notes are included in the drawings, which you can download as
Acrobat v6 PDF documents in the links below. If you need a copy of the
Adobe Acrobat Reader, you can download it free from http://www.adobe.com/products/acrobat/readstep.html.
Aegea is a fairly unique aileron 2m glider. It has the following
* Very low weight (21 oz)
* High aspect ratio
* Moderately low wing loading (6.2 oz/ft^2)
* AG4x DLG
* Relatively generous EDA (6.0 deg)
The main design goal is
to achieve good thermalling performance via the low span loading. The AG4x DLG
airfoil series with
full-span camber control are used to give good speed
performance despite the low weight. The large flaps and ailerons, when set
about +20 degrees, give acceptable winching performance despite the unusually
small wing area of 490 in^2. The generous EDA makes
the Aegea very easy to
thermal, especially at large distances which is a major problem with 2m gliders.
The Aegea can be viewed as
a natural 2-meter implementation of the latest
The Aegea has proven to be a formidable structural
challenge, mainly due to the very thin wing and the large pitching moment
the cambered flaps and ailerons on tow. Everything is sized for stiffness. The
aileron servos don't quite fit, so a careful
fairing job is necessary. The
flap servo had to be put in the fuselage. This helps with CG, but gives a lot of
complexity due to the pushrod hookup and the flap torque rods and
The Aegea II is a redesign consisting of a simple ~10% wing
increase. This greatly improves the practicality of the design, in
that the structural constraints become much easier to meet.
The sparcaps can
be thinner, and one layer of Kevlar becomes sufficient for the center section.
The 4-servo wing is vastly
simpler than the 3-servo wing with the
fuselage-mounted flap servo. The Aegea's tail has proven to be quite generous,
so the same
tail is being used for the Aegea II. If you are considering
building this glider, the Aegea II is strongly recommended.
Fuselage pod (Left) showing servo installation and radio gear. Wing saddle
(right) showing wing connector, switch and wiring.
Pod to Wing filet showing removed from pod (left) and hatch open (right)
A view from the tip of the right wing (Left) and a view of the
wing connector (right)
Aileron servo recessed into the wing pannel (left) and top view of
the mounting bolts (right)
Tow hook options (left) as seen from bottom of pod and wing saddle
Spar and Joiners
Joiner tube, control horn and servo arm detail (left) and top view
of the joiners (right)
Pushrod detail and servo connector plug (left) and panels ready to
be joined (right)
Horizontal stab V-mount (left) and bottom view of stab (right)
Rudder control horn and pushrod fillet (left) and a view of the
pushrod tubing (right)
Building The Spar
The bend in the center panel was a bit more work than I expected, but there
were no major problems and it was manageable.
It sure gets lots of
"howd'yadothat?" questions? :-)
The first thing to make is a 5.8 deg (or
6 deg) wedge out of foam: 2.00" high, 19.0" long, and at least 9" wide. This
will be used to:
* jig up the bent center spar
* jig up the center
wing beds during core cutting
* jig up the center wing beds during core/spar
* support the core during sanding and general preparation
up the center wing beds during bagging
Use high-density foam for the
wedge if possible. It will get lots of use. You can alternatively make two 1.00"
high (3 deg) wedges if 2" dense foam is not available.
The center spar is
glued up with the bend in it using the single 6 deg wedge, or the two 3 deg
wedges. You gave to press down
extra hard right at the center bend so the
kink is "sharp". Use plenty of epoxy at the center kink, so it doesn't pop
prior to application of the glass wrap. The cap/web bond away from the
kink is not critical.
Put metal or glass plates on the foam wedge and
table to make sure things stay dead flat. My spar got a slight wave on the side
was on the foam wedge, because the foam dented slightly under the
clamping load. It still fit within the wing contour, but barely.
have significant built-in stresses at the kink, but this doesn't matter. The
spar is sized entirely for stiffness and doesn't
come close to its failure
I suggest using Kevlar joiner tubes. Very light, and they won't
nick the CF rods. If the permanent rod cracks, your wing is junked,
tubes are much safer than metal. The BD folder as the AL group has a PDF sheet
on wrapping Kevlar tubes.
Before applying the glass wrap, I applied
anti-burst CF tow wrap for 3/16" at the center-panel's spar ends, saturating
The caps are first sanded down at that spot to prevent a
bump. About five 3K tow wraps are sufficient.
The spar wrap is 2.0 oz
bias glass in the center spar, overlapped about 10" in the center (two layers
there). The tip spars got 0.75 oz glass.
One extra 2.0 oz glass wrap was put
over all four joiner blocks.
All glass was applied with 3M-77, then
saturated, blotted, and bagged. No breather is necessary since compaction isn't
Make the bags come off roughly in the middle of the balsa face. Be
very careful not to nick the glass when cleaning up.
Glass failure in spar
sample tests always occurs at the edge of the carbon caps, so round off these
The bolt tab was cut from 3/16" thick PC board.
Aluminum should also work OK. Plywood will wear too much with the small bolt I
To install the bolt tab, cut a small "window" in the glass skin which
matches the tab. Using a bent piece of sharpened piano wire,
hog out the soft
balsa top to bottom and slightly wider than the tab. Make sure the spar caps are
exposed on the inside. Fill the void
with epoxy and push the tab into
position letting the displaced epoxy ooze out.
Once I had the bent spar,
the rest was nothing really special. I sliced the cores apart using the spars
themselves as slicing jigs.
Some sanding was required to minimize the gaps.
The center-panel core pieces also require fitting together at a bevel on the
Any voids can be later filled with Micro-Fill.
core pieces were glued onto the spar with a minimal amount of 15-minute epoxy.
This joint takes no load, and spotty coverage
of epoxy in the joint is OK.
The bottom beds are used for vertical alignment. Masking tape on the bottom spar
ensures that the spar
will be slightly within the foam contour. The gap is
filled with micro balloons /epoxy and sanded flush. The top of the spar is also
below the contour, and that's also filled. The filler is not easy to sand.
Micro-Fill would be a lot easier, but it's weak, and it's
solidly connect the spar to the skin. Hard balsa may be an easier alternative.
A-grain balsa is better for this, since
it's stronger through the thickness
Any remaining voids between the core and spar can be filled
with Micro-Fill. This is also effective on the inevitable dings put
foam during the assembly and preparation. Before filling, a ding should be first
mostly sprung back with steam, by covering
with a wet paper towel and
applying an iron set at about 230-250F.
For bagging the center panel, the
bottom Mylar is one piece, and the top Mylars are two pieces, all hinged
together at the
back edge. Fit the Mylar butt joint in the center as well as
possible to minimize the epoxy ridge.
Tail plan (Acrobat PDF
file CAD DXF file)
Original plans include a single flap servo in the fuselage
Aegea I Plan (Acrobat
PDF file CAD DXF
Fuselage plan I w/3
servos (Acrobat PDF file
CAD DXF file)
Spar Layup (Acrobat PDF
Joiner (Acrobat PDF
4 servo wings with recessed flap servos, and two servo fuselage, revised
skin and spar layups.
Aegea II Plan (Acrobat
PDF file CAD DXF
Fuselage plan w/2 servos
(Acrobat PDF file
CAD DXF file)
Spar Layup II (Acrobat
The Aegea I requires 5 channels, so a Hitec 555 receiver was used. JR241
servos for the tail and ailerons deliver high torque and are very light, and the
HS85MG servo for the flaps is a strong durable servo that will keep from
stripping on hard/inaccurate landings.
On the Aegea II, the flap servo was replaced with a pair of HS81MG's for the
same reasons, and the 6 channel FMA Quantum receiver covers the required six
Your transmitter should be able to handle the programming capabilities for
the version you are building.
Q: How is the wing incidence set, given that the airfoils are set to reflex?
A: Wing incidence is largely a non-issue with the Aegea's all-moving
stab. Setting the wing bottom surface parallel to the fuselage axis
is about right, but a few degrees either way shouldn't matter.
For the first toss, set the stab parallel to the nearly-flat wing
Jan 27, 2004 - JAF
Added CAD DXF files from Tomer
November 27, 2003 - TJ