The NSP Neon [Archive]

skranish

Aug 01, 1996, 01:00 AM

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<title>The NSP Neon</title>

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<img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/neon.jpg" align="left" hspace="5" width="326" height="172">Review
revision 5 Sep 96 

The NEON 400 is a fiberglass and foam Speed 400 class sailplane, manufactured by
Quality Fiberglass and sold by Northeast Sailplane Products (NSP). The current price is
$69.95, but you should check the NSP web page, because they often have specials (<a href="http://www.nesail.com">www.nesail.com</a>). 

I should say right up front that I really like the Neon. It is an easy plane to
fly, and as I have become more familiar with it, my flights have gotten longer. This is
not to say that I would not equally like a similar plane, but I have the Neon flying and I
do like it. Presently I am up to over 17 minutes in still early morning air, using
a 7 cell KR600AE pack. 

The Neon is not exactly a kit - it is more a collection of parts and materials, with a
partial plan and very abbreviated instructions that will only be adequate for experienced
modelers with a lot of creativity. This review is really intended to supplant the
instructions, and to permit me to share my experiences. 

The fiberglass fuselage comes completely assembled, with a separate fiberglass hatch.
The wing is a set of 4 cores, supplied with a set of combined beds - the two center panels
are cut from a single block, so there are only three bed pieces, and the same is true of
the tips. The wing sheeting is supplied as 3" wide sheets of 1/32" balsa that
must be joined together into larger sheets and bonded to the wing cores. There is barely
enough sheeting supplied - save all of the scrap pieces, and you will probably have to add
some from your scrap box. 

The tail surfaces and the internal structure of the fuselage are all cut from a single
sheet 3x36" sheet of 3/32" balsa following a dimensioned diagram in the plans.
The cuts are all straight lines, but unfortunately the dimensions don't really add up
properly, so it is hard to tell if I got some parts correct. 

<hr>

<h2>WING </h2>

Build the wing first, because you will need it to align everything else. 

The wing is a fairly conventional set of foam cores that are to be sheeted with
1/32" balsa. There is no internal spar structure, and the completed wing sections are
wrapped with fiberglass tape at the joints to hold them together. 

The provided instructions for sheeting the wing assume that you will be using contact
cement such as Corebond or Southern Sorghum. 

I decided to make the Neon my first experience with Vacuum Bagging, and I am rather
happy with both the experience and the results. I purchased the $85 Aerospace Composites
E-Z Vac kit from NSP. This kit contains a small vaccum pump, hoses, bag material (really a
very large flexible plastic tube) and bag seals. The only things not supplied in the E-Z
Vac kit are the epoxy and the mysterious Peelply, which I replaced with paper towels. I
used EZ Lam epoxy, which is available from NSP. The instructions in the E-Z Vac are ugly
but adequate; I had never seen vacuum bagging done before, and really had no problems. 

Assemble The Wing Skins 

Cut the edges of the wing skin balsa straight and assemble into skins using your
favorite glue - I still use Ambroid. I have tried both taping and pinning to hold the
sheets together while the glue dries, and I think tape works better. Use the 3M 'blue'
masking tape, which is much easier to remove, especially if left in place for a while.
Sand the completed sheets thorougly. I use a Porter Cable 330 orbital 1/4 sheet pad sander
to speed up this process. The electric sander makes quick work of sanding a large area,
and the result is a very smooth wing skin. 

Attach the Skin to the Wing Cores 

Vacuum the skin sheeting clean. Cut the wing skins to shape with some overhang at the
leading edge and the edges of the panels. The only 'finished' edge at this time is the
trailing edge. Attach the leading edge strips, cut from the 3/32" sheet, to the
cores. Sand the top and bottom surface of the leading edges to match the core shape. Sand
any loose 'hairs' off the wing cores, and vacuum them clean. Assemble to top and bottom
skins together at the trailing edge with a hinge made of masking tape. Measure from the
trailing edge to the location of the leading edge, and put a mark on the inside of the
skin. The cores will not reach to the absolute trailing edge, so you need to mark
where the leading edge goes. Mix the laminating epoxy and apply a glob to the inside
bottom skin. Spread it around the entire skin and scrape off as much as possible, using an
old credit card. Epoxy = weight = poor performance, so remove as much as you can. Remember
that the skins are being attached under PRESSURE, so you don't need much glue, because
there will be no gaps between the skin and the core. Now is the time to add a strip
of fiberglass to the trailing edge, to stiffen it. This is not included in the kit, but I
purchased 1" fiberglass tape from Sal at NSP for this purpose. Simply lay it along
the trailing edge of the bottom sheeting and add a little more epoxy on it. Now lay the
core on top of the bottom sheeting, and turn the assembly around to work on the top skin.
Again apply epoxy, and then fold the skin over the top of the core. Align everthing - you
may want to measure again from the leading edge of the core to the trailing edge of the
sheeting, because that is what determines the wing chord. Place the whole assembly into
the bag, put a piece of paper towel on top of the sheeting to act as Peelply, which allows
air to be removed across the wing surface, and seal the bag. Turn on the pump and wait 24
hours for the epoxy to cure. That is all there is to it! No weights, patio blocks or
whatever. You do not need a flat bu ilding surface, either. 

I bagged each of the center panels separately, and then did both tip panels together in
the same bag. If you are careful, the bags can be reused a number of times. The finished
wing is stiff, straight, and smooth. If the expense of a bagging kit seems expensive, you
can split it with some flying buddies - I highly recommend this as a building method. It
is NOT a black art, and it is NOT hard to do. It is just another modeling skill, and well
worth learning. 

The finished wing panels must be sanded on the ends for the proper dihedral. I sort of
went overboard and constructed a permanent, adjustable sanding fixture for this purpose. A
document describing this fixture can be found of the Silent Satisfaction web site; if you
cannot find it email me and I will send you a copy. 

The finished wing panels should be sanded, and the trailing edge can be sanded fairly
thin because the embedded fiberglass tape adds so much strength. I used the Porter Cable
sander with 320 and 400 grit sandpaper, which gives a VERY nice finish. 

I assembled the wing panels with a thin layer of epoxy, and then wrapped the joints
with fiberglass tape and epoxy. I used 3" in the center and 1" at the tips. Use
laminating epoxy, and make sure you spread it out THIN on the fiberglass. 

I cut a small slit in the trailing edge at the tips and inserted a small piece of
0.007" x 1/4" carbon fiber as a stiffener. It is held in place with CA, and
prevents the tip from being easily damaged. 

A wing of this size is very susceptible to hangar rash, so I made up a simple wing bag
out of a single piece of 'fleece' fabric. It costs about $5 a yard at the local sewing
center, and 2 yards will make about 3 wing bags. At some point in the near future I will
post instructions on how to make wing bags. 

<hr>

<h2>FUSELAGE </h2>

The fiberglass fuselage is made with epoxy, so I used epoxy for all joints to the
fuselage. The fuselage must be cleaned of any mould release by washing it in cold water,
and all areas to be glued should be sanded with 100 grit sandpaper. CA type glues could be
used, but I was not very happy with the resulting joints. If you are in doubt about what
sort of glue to use, experiment by gluing something to the inside of the hatch, where it
can easily be removed. 

The fuselage is actually quite sturdy and should stand up well to rough use. It is not
one of those paper thin flimsy fuselages made for competition HLGs with very short
lifetimes. 

The fiberglass fuselage comes setup to be used as either a Speed 400 sailplane or HLG,
so the nose is still intact. There is no integral firewall or motor mount. The wing saddle
and hatch openings are cut, but the stabilizer mount has not been cut out. The top of the
rear fuselage actually slopes DOWN from the wing, so the stab cannot simply be mounted on
top of the fuselage. 

Two formers must be cut from the supplied 3/32" sheet. The drawings are about
right, but the locations of the holes for the cable pushrod housings are wrong. Make sure
that you drill the holes for the pushrod housings EXACTLY 3/32" from the outside
edges, as this will provide the correct spacing when the pushrod housings are installed
along the wing saddle doublers. The wing hold down dowels are installed in the formers and
are positioned fore and aft. I added a disk of 1/32" plywood to stiffen the dowel
opening. The wing is held on by rubber bands over the center of the wing, like some of the
Goldberg sailplanes. Doublers for the wing saddle and hatch openings must also be cut from
the 3/32" sheet, but I found that 1/32" plywood worked better in the hatch area,
providing more clearance for the Robbe motor control, and stiffening the fuselage. 

Cutting the nose and stab platform on the fuselage CORRECTLY seemed to be a daunting
task at first, especially since no angles are specified in the plans. The prop downthrust
and wing-stabilizer incidence are really critical angles in any airplane, and I wanted to
get them right - or at least know what they were. After a lot of agonizing over how to do
it, I purchased a Speed 400 motor mount disk from Hobby Lobby (#HLSIA503, actually from
Simprop) and setup a jig to get the angles correct. I used the following tools and
fixtures:

<ul>
<li>Robart Incidence meter </li>
<li>homemade work cradle, to hold fuselage, made of 3/4" blue foam </li>
<li>small (6") torpedo level </li>
<li>1/4" threaded bolt, 6" long, nuts, and washers to fit </li>
<li>clay or silly putty </li>
<li>assorted stuff for shims and blocking. </li>
<li>the dining room table (you need a lot of room to do this) </li>
<li>Ace R/C CG Jig </li>
</ul>

The Robart incidence meter is REALLY useful for this kind of work. If you don't have
one, you really should buy one. If it seems to expensive, consider buying one collectively
with a some flying buddies, or convince your local hobby shop that they should make one
available for rent. Model Airplane News published a description of how make one; the
article can be found in Randy Randolph's book ' R/C Airplane Building Techniques'. 

Attach the wing to the fuselage using 2 #64 rubber bands. If the fit is not perfect,
now is the time to get out the sandpaper and correct the fit. You will have to sand a V
into the tops of the formers to get a good fit for the wing. I taped a piece of 220 grit
sandpaper to the underside of the wing center section, so that moving the wing side to
side sanded the wing saddle, and moving it fore and aft sanded the tops of the fuselage
formers. 

After the wing is attached, set the fuselage in the work cradle, and put the Robart
incidence meter on the WING at the root (right next to the fuselage). Add shims under the
front of the work cradle so that the fuselage is 5 degrees NOSE UP. Put some blocking
under the wing tips to hold the wing level; measure under the dihedral joints to check for
level. 

Assemble one end of the 6" x 1/4" bolt to the Speed 400 motor mount disk,
which is a fiberglass disk drilled out for the motor mount screws and ventilation. Use a
pair of nuts and several washers to get a good solid attachment. Tape the 6" level to
the bolt. Put a glob of clay or silly putty (I used homemade stuff, borrowed from the
kids) in the rear of the hatch area. Try dry-fitting the motor mount in the fuselage
first, before applying epoxy. Put the motor mount and bolt assembly in through the hatch
opening, and push the motor mount as far forward as it will go. Ajust the bolt up and down
so that it is level. The glob of silly putty should be large enough to hold the bolt in
place. Eyeball the right-to-left alignment to make sure there is no sidethrust (this may
not be perfect, I would up with a little bit of leftthrust!). When you are happy with the
arrangement, pull it out, apply slow setting epoxy, and put it back together. Let the
whole thing sit overnight. When it is dry, cut off the nose with an X -Acto saw. Don't cut
right at the motor mount; leave about 1/8" overhang. 

When the nose has been cut off, the 1/4" nut is exposed, so it can be removed,
releasing the bolt and level through the hatch opening. Place small strips of fiberglass
and epoxy at the fuselage to motor mount joint to stiffen it and fill any voids. Don't
laugh; this rather complicated jigging arrangement really worked out well. Sand the nose
to match a spinner mounted to the motor; I still have about 1/16" of fuselage
overhanging the motor mount. 

The stabilizer platform was setup similarly. Set up the wing and fuselage again so that
the wing is 2 degrees nose up. Take 1/2 of the Ace CG jig, and put a felt tip pen where
the crossbar would be. It will be used as a marking gauge. You can now slide the base of
the jig around on the table to draw a perfectly horizontal line. Adjust the crossbrace
holder (now a pen holder) up and down to get the appropriate point on the rear fuselage.
Move the jig along the fuselage to draw horizontal lines on each side. Cut along the sides
with the X-Acto saw, and presto, 2 degrees of incidence. Again, don't laugh - it works,
and the plane glides beautifully with no elevator trim required. 

I actually made the stabilizer platform a bit more complex - I installed 2 spruce
crossbraces, and then covered the platform with 1/32" plywood. The stab/fin assembly
is held on by two nylon 4-40 screws that go in at about a 30 degree from vertical angle.
Looks odd, works well. My intent was actually to make the tail REPLACEABLE, rather than
removable. 

<hr>

<h2>EMPENNAGE (TAIL SURFACES) </h2>

The horizontal and vertial stabilizers and associated control surfaces are cut from the
single piece of 3/32" balsa. The shape of the tail surfaces requires that they be
glued up from several pieces; there is almost NO scrap. I used CA to assemble the
surfaces, although it is difficult to sand properly. I added some narrow strips of carbon
fiber on the bottom of the stab to make it harder to break in a bad landing. 

I went to the trouble of making up stab-fin fairings that match the fuselage by making
up a spacer of 3/32" balsa to hold the fairing blocks in place on the fuselage while
they were sanded. These were probably more work than necessary, but they do stiffen the
stab-fin joint. 

The fin and fairings were attached to the stab using epoxy. This is a high stress joint
if the plane flips over - and in general handling - so I wanted to make it strong. Again,
use a slow setting epoxy so it soaks in well. 

I use the covering material as the hinge. I taper the edge of the control surface from
one side, and then use a 3/4" wide strip of covering material to hold the control
surface to the fixed surface. The covering on the other side completes the hinge. I have
been doing this for years, and have never had a failure. 

The plans indicate 1/32" plywood control horns. The material must come from your
scrap box. I cut a slot 1/3 to 1/2 of the way through the control surface, and epoxied the
horns into the slots. 

<hr>

<h2>RADIO GEAR REQUIREMENTS </h2>

The fuselage is just barely large enough for the radio gear and drive train. This is
not bad, as it means that the frontal area is minimized. It does, however, limit the
choice of radio gear and drive train. I used the gear described below and a KR600AE 7 cell
pack in the traditional flat pack arrangement: 

<pre> -- -- -- |
-- -- -- |
</pre>

I also installed the radio a little differently from the installation shown on the
plans: 


<pre> . wing . hatch .
rx battery servos motor
</pre>

There is a little space left between the servos and the motor/controller. There is
enough vertical space in the fuselage to run the battery wires and servo conncetors under
the servos without having any problems with clearance between the servos arms and the
hatch. The area under the wing is completely filled, and I don't see any way to fit a
larger battery pack. 

<hr>

<h2>FMA DIRECT MICRO 2000 RX </h2>

I used the recently released Micro 2000 Rx from FMA Direct (www.fmadirect.com) with my
JR XF622 transmitter. Sal at NSP sells these in all of their flavors, and if he doesn't
have it in stock, FMA will drop ship it direct to you. The Micro 2000 is a very nice
little package with only two problems: The servos connectors are completely exposed, so
they are easy to bend and potentially short out. The weight appears to have been measured
in the graviational field of another planet, because FMA claims 0.6 oz, and mine weighs
0.9oz, with antenna and the integral aileron extension. 

I have experienced no problems with interference, and I have flown with multiple planes
in the air, and at quite a distance out. I should note that the Robbe motor controller is
a relay ON/OFF controller, so I do not currently have any experience with interference
caused by speed control pulse width modulation switching. 

<hr>

<h2>DAD TINA SERVOS </h2>

Sal at NSP likes to push the DAD servos. I had previously purchased and returned
several, but he convinced me to give them another try. The TINA servos are the same size
as the Futaba S133 and Hi-Tec HS-80. They run better than they sound, and I am happy with
their performance. Running off a BEC they are downright snappy. 

The only problem with the servos is that none of the supplied servo arms are
appropriate for a plane of this size - they are all to large. I used a pair of the Futaba
() cut down to only one arm. These a good but not perfect fit, as the Tina output shaft is
a little shorter than the Futaba, and if the output shaft screw is tightened the servo arm
will bind on the case. 

I made a set of offset servo rails from spruce to hold the servos, so that the controls
horns would not interfere. 

I wrapped the servos in wax paper and screwed them to the rails. I then epoxyed the
whole assembly into the fuselage, being careful not to glue the servos in. Then I removed
the servos and added strips of fiberglass and epoxy to strengthen the rail-to-fuselage
joint. 

<hr>

<h2>ROBBE 7753 SPEED 400/45 CLASS MOTOR WITH ATTACHED RSC 210 RELAY CONTROL </h2>

Sal at NSP is also pushing these integrated motor units from Robbe. They consist of a
motor that appears to be the equivalent of a 7.2 Speed 400 and a 10 amp relay control that
is mounted directly to the back of the motor. The circuit includes a BEC and low voltage
cutoff. Also included is the Robbe 6x3.5 folding prop. This is a very nice, simple
combination, and is adequate for the plane. I cut off most of the battery wiring and
spliced on silicon insulated wires with an Astro Flight connector. The holes in the PCB
probably will not take a larger size (smaller gauge number) wire. 

The controller is a simple analog ON/OFF control, and has no smarts or interlock
switch. If your transmitter is set to high throttle when you attach the flight pack, the
motor will turn on after a delay of about 1 second. You have to be VERY careful, because
this type of controller can be dangerous. Fortunately, the Speed 400 motor has so little
power that it is unlikely to cause an injury if started accidently. 

The low voltage cutoff works acceptably with a 7 cell pack. As an experiment I have
flown the plane until the motor cuts off, and then landed and put the pack on the
discharge cycle of my Robbe Infinity charger, with the discharge current set at 0.5A and
the cutoff voltage at 6.0V (likely cutout voltage for the BEC). The remaining capacity is
consistently 35 to 70 mAh, which translates to at least 15-30 minutes of flying time. 

If you are wondering about voltage drop for the relay controllers, I measured a drop
across the controller ONLY of 50mV at about 7A. This was actually near the end of the
discharge cycle, so the drop during most of the cycle will be HIGHER. 

<hr>

<h2>LINKAGES </h2>

A pair of cable pushrods are supplied. These appear to be the smallest gauge Sullivan
cable pushrods. No additional linkage material is supplied. I purchased 0.032 music wire
and mating brass tubing to make the pushrod ends. Soldering the first end of each cable is
easy, because it can be done with the cables removed from the plane. I pin everything down
onto a piece of homasote so that it will not move while being soldered. The second end of
each cable must be done in the plane, so I used forceps as heat sinks so that the cable
housing would not be damaged by the heat of the soldering iron. Roughen up the wire and
brass tubing and use silver solder with flux. I did not make my linkages adjustable, and I
don't think there is room for any other sort of linkage ends. 

<hr>

<h2>COVERING AND FINISHING </h2>

I covered the wing with a mix of Oracover Lite for color (transparent yellow) and
Oracover (Blue and Fluorescent Orange) for trim. The covering added about 1 ounce to the
wing; I think that regular Oracover for the entire wing would have added 2oz (1 oz more).
I don't think there is any need to extoll the virtues of Oracover here; the Lite version
was new to me, and seems well suited to covering a sheeted wing. Be careful about the
temperature; a Coverite iron is recommended because of its precise and predictable
temperature control. 

By the way, it appears that Ultracover Lite is NOT the same material as Oracover Lite. 

The Neon comes with some instructions from Quality Fiberglass about finishing
fiberglass fuselages. I followed these instructions and found them to be pretty useful. In
a nutshell: clean the mould release off the fuselage with cold water. Sand it lightly.
Clean and spray on a coat of primer. Wet san off most of the primer. The pinholes in the
epoxy should now be visible. This is not bad; it means that there is NOT an excess of
epoxy in the fuselage. Fill the holes and other defects with filler from NHP, Tower,
Goldberg or whoever. Sand and reprimer. I actually used my Porter Cable 330 pad sander
with 220 grit sandpaper to clean up the seams by removing a lot of epoxy, rather than
trying to fill in the seam. 

My Neon is now flying in two shades of primer. An attempt at painting the fuselage with
Oracover matching paint from Simprop failed miserably and was sanded off. I am not sure
what the problem was; perhaps it did not like the primer I was using. 

Final colors will probably be Testors spray Enamel, when I feel like emptying the plane
out for a few days. 

<hr>

<h2>SUBASSEMBLY WEIGHTS </h2>

<ul>
<li>7 x KR600AE pack from New Creations 5.0oz </li>
<li>Robbe 7753 with prop and wiring 4.1oz </li>
<li>FMA Direct Micro 2000 RX 0.9oz </li>
<li>Tail complete and covered 0.8oz </li>
<li>Fuselage without pushrods, servo rails, paint 2.5oz </li>
<li>Fuselage with pushrods, primed 3.2oz </li>
<li>Wing, ready for covering 4.7oz </li>
<li>Wing covered 5.7oz </li>
<li>Total ready to fly 21.5oz </li>
</ul>

<hr>

<h2>FLYING </h2>

The Neon is very lightly loaded compared to a lot of electric planes (21.5oz on 390 sq
in = 7.9 oz/sq foot!) which makes for easy flying. I found that full down trim is required
to maintain a stable climb, and the trim MUST be removed as soon as the power is turned
off. This may be somewhat alleviated by planned power train changes, but I expect that a
trim change at power off will always be required. As the battery runs down, less downtrim
is required. Other than the trim change, flying is really very easy. The Neon will circle
tightly without losing much altitude, and will climb in the lightest of thermals. 

On one recent flight I brought the plane down in back of the launch area to circle
tightly and burn off the remaining altitude. As I watched the plane circle, I realized
that THIS WAS NOT WORKING! I had picked up a light thermal at less than 25 feet of
altitude and was going UP. I spent more than 3 minutes in this little thermal. Sometimes I
think you could keep it up by eating broccoli and circling over your head. 

Give the Neon a power-on gentle toss straight ahead and it will climb right out! Give
it a toss with the power OFF and you may be surprised at how far it will go! 

My only real complaint about flying is that the plane gets bounced around a lot in the
wind. I think this is just typical of a plane of this size and light wing loading, rather
than some problem with the plane. I actually fly the Neon in wind that would keep my UHU
on the ground - it really handles well in a breeze, and I will probably use as a light
lift sloper. As a sloper it will have the ability to limp home under power if the lift
dies - a real plane saver for flying over water! 

<hr>

<h2>COPYRIGHT </h2>

The document is copyrighted (c) 1996 by Steven Kranish, and may be used in other forms
of publication (electronic or paper) only with written permission. 

<hr>

<h2>CONTACTS </h2>

If you have any questions, please feel free to contact me at skranish(at)world.std.com
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