EAM marvel User manual

EAM
MARVEL
A medium/small electric sport aircraft with a wide speed range and smooth flying characteristics.
Wing span: 38 in. / 965 mm
Wing area: 356.25 s . in. / 22.98 dm2
Length: 20.4 in. / 518 mm
Weight: 28 – 36 oz / 790 – 1020 g
Power: 125 – 250 Watts

EAM Marvel kit instructions.
The Marvel kit is a product of
Electro Aero Modeling, USA
http://www.eam.net/
e-mail: [email protected]
Power package and radio:
Recommended power is an electric motor in the 150 to 250 watt range. We have used Speed 600
brushed motors, Medusa and Lehner brushless motors so far. A Kv range of 1000 to 1400 is good for
sport flying, and up to 2000 for speed freaks. The Speed 600 power packages are ade uate for good
sport flying performance, and are very inexpensive. Still, we suggest even an inexpensive 150 watt
brushless motor for better power, lighter weight and better efficiency. For light weight and slow sport
flying, you might get away with a good brushless motor as low as 100 watts.
Batteries used so far are Lithium Polymer 3s 2000 mAH to 3s 4000 mAH. Small power systems might
go as small as 3s 1200 mAH LiPoly if you are trying to go featherweight.
Flying weights have ranged from:
28 ounces with the Medusa 028-040-1200 motor and 3s 2000 LiPoly battery to
36 ounces with the Lehner brushless motor and 3s 4000 LiPoly battery and
35 ounces with the Speed 600 motor and 3s 2000 LiPoly battery.
You could probably shave another 3 or 4 ounces off of that with a light weight power package if you
prefer a more sedate flying style, or flying in smaller spaces.
Recommended servos are the BlueBird BMS-371, BMS-380 and BMS-380 MAX. We have found the
BlueBird line of servos to be of excellent uality and a very good value.
Receiver and ESC are up to the builder, as this aircraft will happily fit and carry almost any full size to
micro receiver currently on the market. The Hitec Electron 6 is a good choice, as is almost any good
uality small dual conversion receiver available these days. There are viable single conversion
alternatives too, particularly the Castle Creations/Berg 4 and the Mikrodesigns SPF-5-RXO, both
weighing in at about 5 grams! I would avoid almost all other micro single conversion receivers, as most
are limited range, designed for parkflyer/slowflyer aircraft only, and have very poor noise rejection and
R/F performance to go with their light weight and low price. Spend the extra $20 or so and get a good
uality receiver. You might also consider one of the current crop of loaded antennas to keep from
having antenna wire trailing all about the sky.
Some recommended e uipment and links to the manufacturer websites:
Medusa brushless motor 028-040-1200 http://www.medusaproducts.com/motors/motor-main.htm
Cool Running A-25 brushless ESC http://www.coolesc.com/
Castle Creations Phoenix 25 brushless ESC http://www.castlecreations.com/
Commonsense RC lithium battery packs http://www.commonsenserc.com/page.php?page=intro.htm
Hitec Electron 6 receiver http://www.hitecrcd.com/
Mikrodesigns SPF-5-RXO http://www.mikrodesigns.com/
BlueBird BMS-371 and BMS-380 servos available through EAM

Tools:
Ruler or other straight edge
Clamps
Knife (hobby knife, razor knife or similar – even a box knife or razor blade in a pinch...)
Screwdrivers - various..
Awl (or bamboo skewer – good as a tool and even reinforcement as necessary)
3/16” drill bit
Window screen bead roller (a cheap plastic one can be had at most hardware stores for about $2) or
1/4” dowel with one end rounded off.
Rubber bands
Masking tape
Sandpaper
Materials:
Plastic sheeting (poly drop cloth) for use while gluing to keep parts from sticking to whatever you don't
want them to stick to.
Reinforced strapping tape. Preferably 2” wide, but 3/4” will work too. Used to reinforce the spar and
leading edge of the wing and to hold servos in place.
Covering. Whatever low temperature covering to go over the bare foam wing. We have used packing
tape (Zagi tape), Econokote and Ultarcote. Use what you like, as long as it is a low temperature
covering suitable for use over foam.
Glue.. Our recommended glues are:
Polyurethane glue(Gorilla glue or similar – hereafter referred to as PU). Very good for Coroplast.
Excellent for foam, wood and fiberglass. The advantage and disadvantage of PU is that it foams up as it
cures. This is good in that it fills the joints and bonds really well with the styrofoam wing core, but it
can (and will) ooze out of the joints and is a pain to clean up. Also its amber color is a bit of a problem
unless whatever you use for covering/finishing is really good at covering up the underlying colors.
Goop (Household, Plumbers, Marine, Whatever Goop, Shoe Goo, E-6000 – whichever of these you
pick up first). Our recommended glue for most of this project. Goop adheres very well to the Coroplast
– much better on Coroplast than is epoxy. It takes a tack and skins over fairly uickly, but takes
several days to cure to maximum strength. Once cured it sticks to Coroplast better than any other glue
we have tried except Medium CA. The major advantage of Goop over CA is that it will fill and fillet
the joint, providing more gluing area and a stronger joint on most edge joints. This glue remains
slightly flexible once cured (a bit like silicone) and this helps maintain the integrity of the joint with
flexible materials like Coroplast. Goop will melt the styrofoam wing core, so you cannot use it on the
wing.
Epoxy – good for everything, but PU, CA and Goop adhere better to the Coroplast. Epoxy is good for
the wing assembly.

CA – Medium CA adheres well to Coroplast if the surface is freshly cleaned and/or sanded. Regular
CA is plenty good, but the special plastic CA glues are the best that I have tried. The rubber toughened
may be at least as good, or possibly even better, as they can do some gap filling and they remain
slightly flexible once cured.
Also suggested but not re uired is a 1 3/4” (45mm) spinner. Pick your favorite color...
OK, so much for the preamble, now to the actual assembly.
Our suggest build order is:
Fuselage followed by the
Tail and then the
Wing.
Final assembly and
Flight setup wrap it up.
It should be fairly easy to build this model in three days. Day one would be the Fuselage and Tail, and
starting the Wing. Day two would be finishing the wing and attaching the tail to the fuselage. Day
three would be finishing details like covering and trimming, motor installation, radio installation and
final setup.
Marvel kit and build information is available from:
EAM
http://www.eam.net/
http://eam.net/EAMRC/Marvel/eam_marvel.htm
and also on RC Groups
http://www.rcgroups.com/
http://www.rcgroups.com/forums/showthread.php?t=524984 (pre-release tickler thread)
http://www.rcgroups.com/forums/showthread.php?t=542813 (build thread)

Fuselage:
Inspect the edges of Coroplast pieces for scrap, lumps, etc. Clean up the edges if necessary.
Generally, one side of the Coroplast will be smoother than the other. Pick whichever side you prefer for
the outside, and lay that side down on the workbench. You will crush the fold lines with a blunt tool,
like the end of a dowel – rounded off, or better yet the window screen bead roller. You can even use a
ball point pen cap or any other similar object that will not cut or tear the Coroplast when you drag it
along the fold line to crush it.
Lay your ruler across the fuselage at the nose fold. Align with the back end of the nose section and
using your crushing tool make a single sharp crease across the fuselage. Keep the ruler on the crease
and fold the sections back sharply to make a neat crease for the nose fold. Repeat with the tail fold.
Lay your ruler along the fuselage at one side crease. Using your crushing tool, crush the fold line to a
width of about 1/4” - about the width of the relief notches. This is best done using several passes,
moving the straight edge slightly with each pass. This wide fold crease will help keep the bottom edges
a bit more rounded rather than making a sharp fold.

Using the above techni ues make a sharp crease for the wing bolt tabs. This crease should be across the
ends of the relief notches - parallel to and about 1/8” (3mm) below the edge of the wing seat. Use a bit
of care here, as folding the Coroplast at a shallow angle across the flutes is a bit tricky, and the cleaner
the fold is here, the stronger the wing mounting will be. With the fuselage sheet laying flat on the
bench, you can lay your ruler along the fold line and bend the tab up against the edge. If you have the
manual dexterity, it is better to hold a small piece with a hard straight edge (like the motor mount – use
the top edge) on the tab with the edge lined up on the fold line and lift the straight edge and tab up as a
unit to make the fold. Probably a better fold, but it is trickier to do.
Also using the above techni ues make a sharp fold line on the servo tray / aft
bulkhead. There are small notches on the edges 1” from the back end of the
tray indicating the fold line location. We have found that with most transmitter
and servo combinations, mounting the servo on the right side of the fuselage
results in correct elevator movement without having to reverse the elevator
channel. You should check the fit of your elevator servo in the cutouts and
arrange for the one with the best (snug) fit to be on the right side, with the
back end of the servo tray bent down. The servo try has cutouts to match the
BMS-371 and BMS-380 servos. You may need to adjust one of the cutouts to
match your choice of servo. If you do, try to make sure that the servo is a snug
fit in the cutout.
You can sand the surface of the Coroplast in the areas of all of the glue joints. This is most easily done
before you start gluing. This step is optional but recommended. While PU and Goop adhere well to
Coroplast, every little bit helps. Whether you sand or not, it is a good idea to clean the Coroplast before
gluing.
Fold the fuselage sides up and check the fit with the firewall, the top front / hatch, and the servo tray.
Check that all tabs and slots fit easily, or at least neatly.
If you work uickly, it is easy to get all of the fuselage glue joints done in one session, and they can all
cure at the same time. This makes the major fuselage assembly pretty much a one day process. I find
that the following se uence works best.

Put glue along the bottom front joints and the motor mount joint line. Apply glue to the bottom and
sides of the motor mount too. Key the motor mount into one of its associated slots. Fold the sides up,
bring the sides and bottom together. Make sure that the motor mount keys into all of its slots. Tape the
bottom joints together. Also place a strap of tape across the top over the motor mount to hold the motor
mount joint for the moment.

Put glue along the servo tray joint line. Put glue along the sides and back end (bottom) of the servo tray
/ aft bulkhead. Spread the fuselage sides a bit and put the servo tray in place. Put a strap of tape across
the wing saddle toward the front end of the tray to hold it in place. Put a strap of tape across the back
end of the wing saddle, above the back end of the servo tray too. You may wish to put a light clamp
across each end of the servo tray just to make sure this joint stays tight. The problem with a clamp is
that it may get knocked loose during the following steps.

Find the four nylon wing bolts. Cut 1/2” off of two of them to give them a shaft length of 1”.
Take one of the wing mount spreaders, apply a bit of glue to the tee nuts, fit into the holes in the
spreader and press them into place. Put a generous amount of glue on the top face of the spreader where
the wing mount tabs will fold over and cover, and on the ends as well. Do not get glue in the threads of
the tee nuts! Apply a generous amount of glue to the aft mount tab fold lines. Spread the fuselage sides
slightly and put the spreader in place. Fold the tabs down and screw the short wing mount bolts down
to hold the tabs and spreader in place. MAKE SURE THAT THERE IS NO GLUE IN THE
THREADS OF THE TEE NUTS OR ON THE BOLTS, OR IT WILL BE VERY DIFFICULT TO
GET THE BOLTS OUT AFTER THE GLUE CURES. Place a strap of tape across the mount too, just
to make sure things stay in place while the glue cures.
Repeat the above process for the front wing mount, using the long bolts to hold this end together. It is
somewhat easier to do this before the following step is completed, but if you have already done it, no
big deal...

Remove the piece of tape across the top of the motor mount. Put glue along the top front joints and the
top of the motor mount. Put the top on and tape in place.
Spread the aft sections out a bit and apply glue along the joints. Bring the aft joints together and tape in
place.
Check the fuselage for alignment – that all sides are s uare and that it is not twisted – and set aside for
the glue to cure.
Remove the bolts from the wing mount plates once the glue has properly cured.