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Jul 24, 2008, 08:07 PM
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#16 Trimming and Flying

Since this is a TRAINER I am going to start with basics.

This is an easy to fly beginner type plane but rarely do we get a new flyer that can fly alone on the first few flights.

If you are a truly new flyer without experience have an experienced flyer inspect and trim your plane for the first flight. If you link two transmitters in what we call a "Buddy Box" link and fly with a trainer you will learn even faster. I highly recommend you get a flight simulator and do some simulated flying before flying your plane. Flight simulators are discussed in some detail with links in my blog.

My RCG blog is dedicated to helping the new flyers get the information they need to fly with confidence. You can link to it here:

This is an easy plane to fly. It is easy to keep the plane slow and close which are two qualities of a good trainer. It can easily be flown over grass which is a safer flying area than water or pavement. You can land in any direction because of the floats/pontoons. Because of the pontoons you can take off with both hands on your transmitter. I have done several ground loops and rolls in my playing with the plane and the plane is stronger than most flatfoam planes.

The trainer and the sport versions fly much the same. I flew three batteries through each yesterday and really didn't see much difference in the flying. I recommend the trainer wing because the trainer version is easier to see and stay oriented to. Both take off the ground well with the same motor and battery. Flying weight and attention to detail is going to have more effect on how your plane flies than which wing you use.

We all need to become weight conscious. The plane is usually not the problem when it comes to weight. Most of the weight is decided by the battery, motor, speed control, servos, receiver and all the hardware. I design most of my planes around a 3 cell - 1300 mA battery, the BP21 or FC2812 sized motors, a 25A ESC (speed control), 3x HS81 servos, a Berg or Spektrum receiver and the control rods and horns and motor mount and carbon rods and glue. All of these things together weigh 9-11 oz and this does not include the plane. You can save a little weight by down grading things especially the battery, motor and servos but the power output also goes down and the risk of damaging a weaker servo goes up. This set up will give vertical performance to a plane that weighs less than 16 oz.

Center of Gravity
All planes have a point where they want to balance to fly their best. Having the center of gravity farther back makes a plane more aerobatic but decreases controllability while moving it forward may make the plane seem underpowered and decrease gliding characteristics.

Some planes are very sensitive to center of gravity. This plane is not. I recommend starting at 7" back from nose of the plane (behind the motor). The center of gravity will also help decide if this is a trainer or an aerobatic plane.

This plane is unique because it is easy to make it nose heavy probably because of the floats or pontoons. Most planes tend to be tail heavy. My sport plane with all of the silver holographic tape did come out tail heavy and it is the poorest flyer of the group. Overweight and tail heavy don't go together well.

Building techniques
Planes that are weak and flex in flight are not predictable. Flex tends to happen at higher speeds. Other factors like long pushrods that can bend or elevons that twist at high speeds also can affect controllability. These problems are common in flat foam planes.

I had to make modifications to my Capricorn to strengthen the wing. The new fanfold foam is not as strong and the old fanfold foam was. The new fanfold foam Capricorn needed a tip to tip carbon rod while the older fanfold did not. I already had a carbon rod on the front of the wing to reinforce the motor mount and a carbon rod down the inside of the center the of the wing to keep the motor from tearing out of the plane in an accident.

I added a carbon rod across the back of the wing after the wing was already built and also added some foam bracing on the bends of the wing to make the plane ridged enough for aerobatics.

We have also learned that a hinge will not work if the wing is flexed. The control surface will return to a flat position if the wing is bending and the plane will be out of control.

The push rods may also flex which may have a similar effect. Running a pushrod through a 1" piece of soda straw in the center of the pushrod that is glued to the wing may be all you need. I have also had to use heavier pushrods or move the servo closer to the flight surface in some cases. The angled wire from a central location looks better but doesn't work better. Sometimes a pushrod will flex when it is pushed but be OK when you are pulling. Make sure to check both directions.

The flat foam elevons may also twist from one end to the other. Center the control horn in the flight surface if you can. Long elevators, ailerons and elevons are more at risk than shorter ones. Luckily the Capricorn has short elevons but it may have long push rods.

Surface movement
The amount of movement in the elevons and rudder will decide if you have a trainer or a stunt plane. You have to have enough movement to put the plane through basic maneuvers but too much will make a plane with this small of a wing span snap roll. I have already said that this plane is very sensitive to the rudder.

Make sure all four elevons move the same amount. With mixing on make sure that both elevons come up when you pull back on the stick. The right elevon goes up and the left elevon goes down when you push the (right) stick to the right. The left elevons come up and the right elevons go down when you move the stick to the left. The left stick rudder should be centered. Throttle off.

Elevon Trim
Set all four of the elevons at 0 degrees, They should be the same angle as the wing which is unusual for deltas and flying wings. The up thrust of the motor makes it so it doesn't need or want the surfaces refluxed (or slightly up).

Rudder Trim
This plane is unusually rudder sensitive. The updated new smaller rudder is very adequate and would still work well if it was cut down even more. This design is also stronger than the larger rudder.

I found that even a couple of clicks of rudder trim effects the elevon trim. I can snap roll just with the rudder. Rotation stops instantly when I release the sticks. On the ground the plane steers easily with the rudder.

Motor Angle

The motor angle helps the plane fly the same with different throttle settings. I have the motor set at about 4 degrees up thrust. If your plane pulls up with a throttle increase the motor is aimed too high. If the plane pulls down the motor is aimed too low.

Motor Power
I have a real scientific way to test the motor. First I try the hover factor of holding the plane in the vertical position go WOT (wide open throttle) and feel if the plane has power to hover, then I just go out and try to fly the plane. All planes don't have to hover to fly well but I have a quick idea of what the plane will do when out flying.

I first tried this plane with a BW 1300 and was seriously disappointed. The BP21 and FC28-12 brought the plane to life.

You notice that I only recommend two motors. That is because I design most of my planes around them based on the weight and speed of the plane. There will always be new motors and batteries. If you find something that works better please tell us and we will add it to the list.

LOG - Lift Off Ground
This plane is easy to take off. It is easier to take off with both hands on the transmitter. You must make sure you use the (left) rudder stick to steer on the ground. This plane is sensitive to cross wind so start with taking off directly into the wind. The elevons will drop a wing and may roll the plane over if you try to steer with the right stick. You need the rudder on the ground but have to make the mental switch to the elevons for most of the flying in the air then back to the rudder on landing. I remember reminding myself on final approach to switch to the rudder on landing. Now it is just a reflex but it is something that needs to be learned.

I hope you enjoy this plane as much as I do. I have been very pleased with the performance and controllability in the small field environment.
Last edited by Lee; Aug 31, 2008 at 01:26 PM.
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Jul 24, 2008, 08:08 PM
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#17 Modifications

Gene Bond a well known plane designer drew plans for a variety of modifications to the SMART DART on post #60 of the Smart Dart thread. Just looking at these modifications makes me wonder what could be done with the Capricorn.

Let's see what you can come up with.

Last edited by Lee; Aug 10, 2008 at 04:53 PM.
Jul 24, 2008, 08:09 PM
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I'm building some more light sets for the warm summer nights. This thread is a tutorial for LED wiring I did last year. I copied the information but for pictures and more information look at the links.

The Pinata and the Assassin are sister planes. The ROSWELL is a 36" delta design I have been playing with for 20 years. This video shows the Pinata and Roswell night flying with Christmas lights. The LEDs I use now are brighter. I need to shoot more night video

Nightflying with Pinata flying wing 11-07 (4 min 20 sec)


Many flyers are building their lights into their planes but often I want a set of lights to tape to a plane for that occasional night flight. I don't want to have to commit a receiver, ESC, servos and plane to a plane I fly only occasionally at night. I want the plane to also be able to be flown in the day. I don't fly often at night but want to be able to go with very little notice.

I wanted a more durable set of lights that wouldn't short out and could take some abuse. The sets shown here meet that criteria.

The lights are amazingly bright, far brighter than the glow wire, glow tape or glow sticks and probably brighter than Christmas lights at their best. I took them in a 20'x16' family room and they put lights on all 4 walls. These reds and blues are as bright as the whites.

These lights are like a flashlight and can be aimed so you don't have to cover the plane with lights to cover the plane with light. I taped the lights down the center from nose to tail and then back under the center of the plane on the bottom. I then went through the lights and aimed them at the outer wing so they gave maximum light and put a small dab of hot glue from a hot glue gun to keep them pointing in the right direction. They are amazingly effective and are bright enough that I can see the ground on approach which makes landing much easier.

You can color white LEDs with permanent markers to get a desired color. It seems to work for the desired effect if you can't get the color you want.

When you put a resistor on each LED and wire the lights in parallel you may lose one light but the entire set will not fail unless the wire breaks. It's more work but worth the effort. These LEDs come with the resistors anyway.

I bought MEGA BRIGHT RED, WHITE AND BLUE 5 mm lights from the following vendor on Ebay. Because he is on Ebay his prices expire but you can go to his store on Ebay and look at his present listings at:

I bought three colors (white, blue, red) of LEDs of the bright 14k-18k LEDs which are also available at other vendors.

All of the LEDs came from the seller with resistors to run them off 12V. They all look the same color and only show their color when they are on. I marked them with the a permanent marker when I took them out of the packages so I could tell them apart while building.

LEDs have different brightness ratings usually between 3000 and 18000 mcd. Some also have options for different angles of focused light. I'm not an expert in LEDs and so took the advice from a friend and got the lights listed. I also heard the brightness ratings may be misleading because the more focused lights have a higher mcd rating but not produce more light. Many flyers are satisfied with the 5000 mcd lights in their planes.

I set up two configurations for testing. One set has 2 X 60" wires. I built R and L sides and 10 LEDs on each string. I have 4 colored and six white on each side. I used the LEDs listed above. My other set has 4 X 24" strands of 6. All 6 lights in each strand are the same color with one strand of red, one of blue and two of white.

I built my LED light sets with heavier wire to make them more durable. I used 24g speaker wire that has single strand wires. I cut down the wire on the resisters and LEDs and soldered them about 3/8" apart then put heat shrink over the resister and both sides of the wire connections and solder joints on the LEDs. I can roll up the set with the lights on without risk of shorting them out.

All speaker wire is not the same. The solid core or single strand wire is so much easier to work with on this project. The multi strands would sometimes separate and were hard to fix once they came apart. I used the 24 gauge, two conductor solid core clear speaker wire from Radio Shack. One side of the wire is marked with a white line to mark polarity. A smaller gauge wire would do. The heat shrink is a hassle but well worth the effort. These lights can be rolled and twisted together and won't short out.

I put my 30 W soldering iron in a vise to leave my two hands free to make the mini solder joints. It is much easier and faster than holding the soldering iron. I used flux and pre-tinned the leads so I could keep the soldering time and temperature down while working with such small leads on the resistors and the LEDs since both can be ruined with too much heat. I did destroy two of the bulbs I was working with by overheating the wires while soldering. Considering I soldered 48 bulbs and am learning to work with LEDs I thought this wasn't too bad.

It is time consuming but worth the effort to get the sets of lights to lay flat. It is also a good idea to put the power plug in the middle of the light set and have 2 or 4 wires exiting the power plug for easier attachment on the plane.

This is the process

I cut 20 pieces of 5" wire.
I found the polarized mark on the speaker wire
I soldered the marked polarized wires to the red battery lead plug and heatshrinked the connections
I repeated with the ground or black battery wire and the other side of the speaker wires.

At this point I have 2 speaker wire leads out of a plug.

I prepared the all of the LEDs before starting to wire them by:

Bend the LED leads out in opposite directions
identify the flat side of the LED and cut off the other side to about 3/8"
Cut one side of a resistor wire down to 3/8"
poke both wires to be soldered into the flux
Pre-tin the wires by briefly touching them each to the tip of the soldeing iron with a small amount of solder on it
solder the resistor to the LED.

I then would work on one side at a time and I would:

slide on a 3/4" piece of heat shrink tubing
then cut the length of each side of the speaker wire so the LED wires could lay flat.
strip off 1/4" of insulation on each side of the speaker wire.
flux and pre-tin the speaker wire
cut the wires to the desired length on the resistor and LED
flux and pre-tin the wires.
then would solder the resistor side of the LED to the positive or red battery side of the wire
then repeat with the flat side of the LED wire to the black battery lead side of the wire
I would then cut the next 5" wire end lengths so the LED wires would lay flat making sure to maintain polarity
I would then solder it to the next 5" extension of wire and
slide on a 1/2" piece of heat shrink for the flat side connection.
I pushed the 3/4" heat shrink over the resistor and
the 1/2" heat shrink against the flat side of bulb
using a lighter shrink the heat shrink.

Repeat until desired set is built. Last bulb is on the end without an extension wire.

Once I got up to speed I would twist the wires together before soldering the source and extension wires to the resistor and LED ends which was much easier. The most difficult parts are to get the wires the right length and remember to put the heatshrink on the wire before soldering.

As a comparison the 20 Christmas lights as discussed in other posts, that I used in the past, would weigh 1.8 oz and would require 1.4 A and are more fragile so the LEDs outshine them in most ways.

It was a enjoyable project but with all of the soldering and heat shrink it took me 2-3 hours to solder it all up.

Total weight with the plug, 10' of speaker wire, 20 x 5mm LEDs, 20 resistors and 40 pieces of heat shrink is 1.0 oz. The set uses 0.34 A. I am pleased.

Late Note:

Went night flying agiain last night. I am really enjoying the night flying. It's cooler at night even when it's hot in the day and the local ball fields are available after dark.

I have learned that having a complex pattern a colors isn't always good for orientation. On my fist attempt I have red white and blue on both top and bottom. At a distance it is hard to tell the difference although it is obvious close up. After getting slightly disoriented in snap rolls and rainbow rolls I put just red and blue on the top and white on the bottom on the second plane I set up.

I like the white on the bottom because it helps me to see the ground on approach and take off. This plane does not have the obvious plane shape to help with orientation at night. The lights are in a box shape no matter what angle you look at the plane from.

This is still my favorite night flyer and I do wild aerobatics even in the dark which most night flyers won't do because they are more sane than I am.

The worst problems I have had is forgetting to turn off my head lamp when taking off and having a whole flock of moths and bugs in my face while I am trying to both fly the plane and turn off the headlamp.

Last edited by Lee; Jul 07, 2009 at 01:01 AM.
Jul 24, 2008, 08:10 PM
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#19 Reserved
Jul 24, 2008, 08:11 PM
Lee's Avatar
#20 This is a copy of post 527 from the Capricorn thread in Wattflyer.

This is a summary of what Larry has said in 527 posts by DBacon. Go to the above thread to open the attachments. There is a great schematic drawing there. Go read their thread it has great information there.

You will notice some differences from some of my suggestions. Maybe their way is better than mine. Don't hesitate to experiment.

DBacon's Avatar

Join Date: Jun 2006
Location: Shelby Twp, MI USA
Posts: 54

Default DBacon version

I will post my accumulated notes, all copies of what you have said, so it should sound familiar. I added some notes, and edited things, but it is true plagiarism at it's finest. As Sir Francis Bacon said "plagiarism is the most sincere form of appreciation" (NOT AN EXACT QUOTE...) Here is the notes:



If you plan to fly off water - get some CorrosionX water proofing stuff. They have it at the Ace hardware/lumber yard next door to the hobby shop. It can be found in most Ace hardware stores and many Marine supply stores.
Get the standard (NOT the heavy duty) Marine or Aviation CorrosionX. I prefer the pump spray bottle and not the aerosol spray can, but either will work. The pump spray is a lot easier and neater because you can take the lid off to poor it into a jar for use. The aerosol can is a lot of trouble to get some into a jar for dunking. You will waist a lot.
This stuff is like medium weight oil - about 20-30 weight or so.

Pour some into a large mouth glass jar or small deep bowl. Make it enough to completely cover the parts. Dunk the rx, speed control and motor into the jar and swish it around so that the stuff penetrates all the nooks and crannies. Take the rx case off, if you can, so the gunk can get to the electronics easily. It needs to contact and coat the electronic circuit boards.
Make sure it gets inside the heat shrink on the speed controller too. Get all the air bubbles out. Also be sure all the connectors get a dose.
Once the part is all coated remove it from the oil - I use long nose pliers - and let most of the stuff drip back into the jar. I then put the parts onto several layers of paper towels and let them drain over night. Turn the stuff a couple of times to try to get as much of the oil to drain out as possible. Wipe the outsides of everything off as best you can with more paper towels. Then wipe it again - then wipe it again - then wipe it again and again etc.

Be warned - this stuff stinks some (my wife hates it) and if you get any onto something else you will never get glue or tape or paint to stick to that place again. Its a good idea to wash your hands very very well after using it and before touching anything else. Its persistent stuff!
You may think you have drained the part very very well and then lay it down on your wife's pretty new kitchen table - your doomed because another drop will decide to drain out just then
If you want to use sticky back Velcro on the rx or speed controller, you will need to wipe the outside of the case or shrink tubing down with alcohol to get it as clean as possible or the sticky will never stick. Don't get the alcohol on the electronics as that will remove the waterproofing. It also may kill the circuit.
Sounds like a lot of trouble but it will save you blowing up a speed controller or rx if (when) it gets dunked under water. Believe me - if you fly off water it will end up upside down at some point!

I have deliberately run treated motors and controllers and rx's while they were completely under water. Amazing stuff. The TV commercial shows them treating a TV set then tossing it into a swimming pool and watching TV under water.
I put a lid on the used CorrosionX left in the jar and keep using it till its gone. Keep a lid on it as it stinks and may evaporate over time. If you can get the bottle instead of the can you can poor it back in.
I re-treat my stuff once a year and it is doing great. The only things that it didn't work well on were servos. 1 out of 3 or 4 went bad when treated.

On my Capricorn, itís not unusual for the plane to get blown over upside down in the water. (itís the wind - not dumb thumbs.) More often than not, that same wind will catch it and blow it right side up again. So far, I have been able to wait a few moments and fly off the water again as if nothing had happened. I have had the plane upside down for as long as 15-20 minutes with the receiver, controller and motor completely submerged the entire time. When it flips back upright again - off I go with no issues. I have found that sometimes it doesn't work. If water is touching the pins on the receiver crystal it will de-tune the receiver and it wonít work until the water drains off the crystal. If that happens, just remove the crystal and blow on the socket and you good to go again.

I do NOT treat servos as mentioned above. Too many of them die on me. I also do NOT treat my batteries. There is tape covering the electrical contacts on most all battery packs. The CorrosionX causes the tape to stop sticking and uncovers the contacts. Not a good thing.
After a dunking I do NOT use that battery pack again that day. I take it home and put the battery in front of a fan to dry it out as best I can. I leave it there for at least a day before re-charging. So far, after many many dunkings, I have had no battery problems.

Do NOT fly off salt water. It will kill the battery packs in just a few minutes and I don't know how well the CorrosionX would work on protecting the esc's and RX's in salt conditions. They use it for Marine electronics, but they don't normally expect a complete dunking in salt water.
CorrosionX is truly amazing stuff.

P.S. Do NOT be tempted to run your motor while its under water with a prop attached to try to 'motor boat' back to shore. The water has soooo much extra resistance compared to air that the motor will draw huge currents and over load. You will probably kill the controller or battery if you try it.
As always with electrics - the FIRST thing to do if you crash - on water or land - is kill the throttle.


Any small brushless will work fine if it can put out 100 watts or more peak and you could probably fly "sport" with as little as 60 watts.
The wing loading of a typical shock flyer is about 4.5 ounces per sq foot. A Tensor 4D is down to about 3.5 oz/ft. The Capricorn is about 2.5 oz/ft at the lightest.
My latest version weighs around 16-18 ounces all up and I like flying it on a Mikrodan 2505 motor with a 3S TP 1320 pack. It draws about 9 amps for around 100 watts peak with a GWS 9x5 prop. Itís more than light enough to fly in the smallest spaces or indoors yet still has plenty of power for wild maneuvers and water or wet grass takeoffs and is a hoot to fly outdoors in the wind.
The vast majority of each flight is spent well under 1/2 throttle.

3. CG

I like flying with my CG about 9-10 inches back from the leading edge. I have flown it as far as 15" back but thatís a bit much.
Jed and most other folks prefer being about 7-8 inches back - right at the rear of the sponsons. Itís a lot more stable and tracks better with it at that point.
However, if you want to do those super tight loops you need it back about 9".

When your flying off water and the model gets wet, the CG moves back a good bit. Again because most of the surface area is behind the CG anything added to the entire surface moves the CG rearward.
Itís more noticeable the further back your CG us to start with. If you have your cg around 7" back it wont be a problem, but be prepared for a more sensitive elevator response.


Specific Control Hardware

1. AXI 2212/26 motor ( or a torque t22/930 from (
2. APC 11x4.7 prop--towerhobbies
3. Berg 4 receiver----towerhobbies
4. Thunderbird 36 speed control---towerhobbies
5. 1800-2600 3 cell lipo
6. Velcro to stick everything together
7. Blenderm tape for hinges.. top and bottom----medical store or on line
8. HS 55 servos or HS 65 servo---towerhobbies
9. Krylon H2O paint...It must be H2O or it will eat the foam----Walmart
10. Dubro 930 horns---towerhobbies
11. Durbro easy connecter---towerhobbies
Controls - General

HS55's servos seem to have plenty of power. I have stripped out several of them after crashes though. I like the '55's because they are cheap and have enough power, but also because if you bump a surface while loading etc it will NOT automatically strip the gears like some of the small servos do.

Original has enough ground clearance for a 16" prop so on my next one I will mount the motor down lower - even with the top of the main wing. That will reduce the need for so much UP thrust .

HEAT SHRINK - I haven't had any fail in flight, but I have had a couple tear after hard crashes that also stripped out the servo gears.
Some heat shrink seems to be better than others though. I had some that was kind of stiff before shrinking. Felt more like drinking straw plastic rather than the usual rubbery stretchy kind. That stuff didn't work at all. It tended to break after just a couple of bends once it cooled.
Just remember to sand the ends of the carbon rods smooth so they are not sharp and have no rough edges. Also bend the joint 90 degrees as you shrink it - in the direction its going to be working once its installed - and let it cool in that position.

The elevon push rods were made from 1/8" carbon tube split down the middle. The last inch or so is not split and has an outer sleeve to stop the split at that point. The back of the push rods have 1" bits of threaded rod lashed and glued in place. The clevises go on the threaded rod and allow individual adjustment of each elevon.

Pull-pull could be tried as per design on ďPull-pull.dwgĒ

I decided to do all the hinges and servo work before putting the W into the wing; much easier to work with everything flat. The wing panels are joined with tape at this time to allow them to hinge and form the W easily.
Added water rudder area is glued on bottom of fin for better water steering.

The only other change I make in the tx is to run a lot of expo. I generally use around 60%-70% expo on elevator and aileron. Zero on rudder. I dont use dual rates - Im maxed out all the time.

However, thats because of the way I like to fly.

How you set up the controlls as far as throws, expo, dual rates, etc depends mostly on how you like to fly.

I like to fly on the ragged edge with this thing - very tail heavy and as much throw as physically possible. The rudder goes about 60 degrees either way and the elevons go around 50 degrees up/down on mine.

Thats what you need if your going to do wild manovers one second then slow to a crawl the next and cruise 1 inch off the water or drag one sponson around the circle. Thats also why I fly with 60%-70% expo so I can keep it stable and smooth at slow speeds and still do wild stuff without having to flip a switch.

Most people have a hard time with that, but its what Im used to.

I would recommend you start off with a mild set-up to get started unless you are a wild 3D junkie who like to do low inverted spins and tumbles at hi speed.

I would set things up with about 45 degrees of throw on hi rates and mabey 15-20 degrees on low rates and set the CG at around 7 inches from the pointed nose to start.

Fly it and see how you like it. Adjust the throws and cg to taste as you get used to it.

This thing flys a bit differently than most any other plane out there and it takes a bit of adjusting.

The best advice I can give you is:

1) dont fly at full throttle all the time. This thing will take off and cruise around nice and easy at very low throttle settings. Its a ***** cat at slow speeds. It can get a little psychotic at hi speeds and a rear CG

2) Use the left stick.

I do 90% of my turning with the rudder. When Iím low-n-slow I control altitude with throttle and use the elevator to set the angle of attack and steer with rudder.

I have use several different things for color. The sponsons are painted - mostly with Krylon H2O but Iíve used other latex paints as well. On the wing I am currently using some low temp covering material - I think its UltraCoat but canít remember for sure - the labels are long gone I have also done hand painted stripes with craft paint and a foam brush when I was in a hurry.

Regular Monocoat is not a good idea as the shrink temps are too hi and the foam will melt. Make sure what you use says 'low temp' somewhere on the label.


Be careful with paint. If you paint the entire thing it adds a LOT of weight. Thatís a lot of area and it adds up. It also tends to make the model more tail heavy so keep that in mind too as most of the paint added will be behind the CG.


On thrust angles - how much up thrust you need varies depending on how hi the motor is mounted above the top V joint.
The taller the motor mount, the more up thrust you need.
On my small version, I was able to mount the motor very low - right on the V. That one didnít need any up thrust.
Lowering the motor height caused more of a change than I expected in the thrust line. I think Iím going to have to add some DOWN thrust.
I wonít make that decision until I get a chance to fly it outdoors and do some more trimming flights. I need to get the CG right before I mess with the thrust angle. I think the CG needs to go back more too, but I need some more room to test that properly. Our indoor space is just too small to allow for proper trimming. Youíre constantly turning to miss the walls!
Also got to do some trimming flights. I think the thrust line is fine. The CG just needed to go back a good ways. Iím almost perfect now.
Right thrust isnít critical. This isnít a pattern plane and I doubt you'd notice if it was set to zero. I wouldnít bother trying to cut the slots on an angle.
What I do is just glue the stick on slightly cocked to one side, then add a side brace in Depron. Sometimes I have done a brace on both sides when Iím running larger motors.
All of mine do have a small amount of right thrust. I donít measure it - its TLAR


For glue on the main wing joints - Gorilla brand glue or any similar expanding Polyurethane type glue will work best by far. I like the Sumo brand because its white and looks the best. It has the worst bottles though. Very tough to squeeze. I have used CA and epoxy but they seem to be more brittle and the joints have broken easier.
I usually use foam safe CA on the motor mount and to glue in the rudder but the PU or epoxy will work as well.
My current favorite for the wing joints - by far - is the new Gorilla Fast Cure clear polyurethane glue that dries white. I also like the Sumo brand but the bottles are tough to squeeze. I use some foam safe CA here and there when Iím in a hurry.
I just found some new Gorilla glue.
It looks clear in the bottle and says "Quick Cure/Dries White".
I just tried some and it does dry faster and ends up white.
The bottle is much easier to work with than the Sumo glue too.
I like it a lot so far.


I found out that the blue is Styrofoam and the pink is the cyanosomething?
That means that the blue would be relatively safe to cut with a hot wire, but the pink will put out very very nasty fumes.

1) After you cut the main wing parts out, bevel them for joints and for hinges. Since Blenderm tap slowly ďcreepsĒ, use modified Monocote hinges, requiring two V-shaped mating edges, ===><===.

2) Start with the 2 panels on one side and bevel then tape the outside of the joint while its laying flat.
3) Turn it over and add glue to the joint.
4) Weight the inside piece and prop up the outside tapered piece 4" to 5" off the table. That will give the proper angle. Brace it some way so it canít move while the glue cures. I use scraps of Depron and some pins.
5) As the polyurethane glue cures, it will expand up out of the joint. During the first 1/2 hour or so you can run a Popsicle stick over the joint and scrape off the excess as it comes out. You will end up with a nice joint if you stay after it from the beginning. Wait too long and you'll have to sand it or try to cut it off. Mix the glue with water first to speed it up.

Once the outer panels are done, you can do the center joint the same way. Pre-cut the slots for rudder then put glue in the joint then flip it right side up and put braces at each end then let the glue cure. I donít bother scraping out the excess as it foams up because it will not show and its impossible to get to using this method anyway

A note on the angle of the outer panels - it doesnít matter
I just checked and I have 3 different bend angles on various versions. Prop up the outer panels anywhere from 4" to 5". They all fly fine ")

The sponsons are made from 2" thick pink building insulation board. I get mine from Home Depot in 2' wide x 8' long sheets for about $20 or so
I have also used pool toy "Noodle board" foam for the sponsons. It has the advantage of being similar to EPP foam in that it bends and springs back after a crash. The down side is that is a pain to work with as far as getting glues to stick and it only comes in ugly colors.

Try painting or low temp iron-on covering to waterproof the foam, if it absorbs water (Blue, Pink, Expanded bead, Styrofoam all absorb water.) This is still an unconquered problem. May try Depron in an inverted ďTĒ or a channel with an open back for drainage.

Larry covers the bottoms of his sponsons with plastic cut from large jugs of cat litter. Glued on with 3M 77 spray adhesive. It lasts forever and is very slick. Works better on grass and snow than duct tape, though Duct tape will work and is cheep and easy. It wears out fast on pavement but is easy to replace.
Others have had good luck with the thin baking sheets from Target. They are Teflon or something similar. Very slick and tough but pricey.

Put the electrical components in the space between the deck and the under brace - you will have to make the brace width to fit. Lay this out first and cut the fin slot before final assembly
Seal up the front unless you suspect overheating is a problem.
In the winter it would probably help keep the packs warmer so you would actually get better performance on very cold days.
Be sure to leave the back end open so any water that does get inside can drain out.

To mount the sponsons cut a 'v' shaped notch in the top and then glue them to the outer joints of the 'w'. The angles donít have to be perfect - the Gorilla glue will expand to fill in any gaps.

Servos - wrap with masking tape glue them down, on top of the wing.
Donít cut a hole in the deck for servos; mine have been filing up with water since I did that.

Wing strength, two choices:
1. Double up the layers in the front, for strength. It also makes the plane stiffer so it rolls better. It keeps the main wing from breaking at the join line where the under brace glues to the wing deck.
On hard landings the sponsons tend to spread outward. That puts a bending moment on the center wing panels and it tends to break along the line where the brace is glued on.
2. A dowel running between the sponsons works well. It can get caught on tall weeds It is a lot stronger though.

My doubled-up section holds up fairly well but it still can break along that joint on a rough landing. Last time I broke it I glassed the joints about 4" back with .5 oz glass and water based varathane.
Keep in mind I tend to be rough on mine. I like to fly close to the ground/water and many of my low loops tend to bottom out an inch or so below ground level. The "spring action" of this design allows it to flex and come back - but only so far
This thing is long and flexible as far as twisting. When you give it a roll command the fuse has a tendency to twist in the opposite direction which tends to counter act your roll command. The bottom brace was originally added to fight that, then made larger.
When I added the top front layers that really helped a lot. I suspect a wider bottom brace would have the same effect.

I donít like using hollow LE mounted tubes in this situation. The structure needs to be able to flex or it wonít last long. On the 6MM version I think 2.5mm or 3MM rod would be fine.
I still prefer the doubled front edge because it serves a dual purpose - it reduces the wing twist and helps roll rate at the same time.
If you do use carbon - remember I donít have any really good reason NOT to - it needs to be at the front as I mentioned before. Thatís where most of the weight is going to be carried.


By the way - here is how I test for correct thrust angles.
First you must get the CG set correctly. If itís too far forward or too far back, the up thrust cant be set as well.
Again, this isnít a pattern plane so itís not all that critical.
Get the CG where you want it, the closer to ďneutralĒ the better (but twitchier) it will be.
Neutral CG requires no trimming for level flight between inverted and upright.

Next, trim the model so it flies straight and level at full throttle. Then abruptly cut the throttle.
If the model climbs when you chop the throttle, then you have too much down thrust.
If the model abruptly dives, then you have too much UP thrust.
Ideally, the model should start a slow decent with no abrupt up or down pitches when the throttle is cut.
You can also check by starting at low speeds and abruptly go to full power. If the model climbs radically = too much UP thrust.
If it dives = too much down thrust.
Be aware that climbing/diving with throttle changes can also be caused by nose/tail heavy condition so thatís why you set the CG first.

To check right thrust, first go high then point the model at you and dive at about a 45 degree angle - power off.
Trim the rudder for a straight 45 degree glide with no side to side turning. By the way - this is also another way to check for issues - the glide should be dead flat on the 45 with no climb or diving away from the 45 degree line.
Once the rudder trim is set, then do the same thing but do it climbing away going UP on a 45 with power on. Does the model pull to either side? Adjust side thrust as needed.
You can also check by climbing straight up and see which way it pulls, but the 45 degree climb is going to be closer to your normal flying speed, so I like it better.

I also copied your drawing, converted it to inches, and lowered the motor, I will get that added to this post too.

Attached Files
File Type: pdf Capricorn y08m07d24.pdf (19.8 KB, 11 views)
File Type: pdf Monocote Hinges.pdf (14.0 KB, 8 views)
Last edited by Lee; Jul 27, 2008 at 04:34 AM.
Jul 25, 2008, 05:09 PM
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Lee has done an excellent job with his LED lighting tutorial up in post 18. Well done, Lee, not just on that but your entire Capricorn tutorial.

LED soldering tutorial

Lee had originally asked me to post pictures showing the build process for LED lights, but since I never got around to it, and since his pictures are much better and more complete than mine would have been anyway, I won't duplicate any of that. Instead, here's a link to an LED light soldering build log I made last year. There's also a video tutorial, in case anyone finds that helpful.

LED light soldering tutorial (This has some play by play commentary for the video below.)

Soldering LED Lights (4 min 15 sec)
Last edited by Darth_Elevator; Oct 21, 2008 at 11:01 PM.
Aug 07, 2008, 08:44 AM
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And here's a video of my Capricorn night flying test.
Capricorn night flying test (1 min 35 sec)
Last edited by Darth_Elevator; Oct 21, 2008 at 11:02 PM.
Aug 07, 2008, 08:45 AM
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#23 Reserved for LED setup instructions.
Aug 07, 2008, 08:47 AM
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#24 Reserved for LED setup instructions.
Aug 07, 2008, 08:47 AM
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#25 Reserved for LED setup instructions.
Aug 15, 2008, 11:32 PM
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Your write-up in post #16 is excellent and thoughtful, it should be required reading for all foamy and park fliers. Many things in there to guide the new builder, and with each one I read, I would say to myself; "How many times have I seen that overlooked?"

For you new pilots out there, you are valuable to us, we want our hobby to get bigger, better and stronger, and if you get discouraged that makes us one less strong. Please join a club and you will get expert advice like this, although maybe not as clear and concise as this.

When a seasoned RC'er inspects your plane, he will see these things, even if it is not in such a well organized manner as this. He may discourage you from flying that day, but he doesn't want you to be discouraged from the hobby.

It is obvious to me that Lee feels the same way, so please read his write-up carefully and don't skip a single detail. All it takes is one malfunction to crash the plane.
Sep 13, 2008, 11:32 AM
Registered User
Plumbers flux is absolutely the WRONG flux to use. It is acid core and will destroy the connections. The proper solder is electronic solder, can be obtained at radio shack or the like, and has the proper flux built-in (rosin core). Never use anything other than rosin core solder for electronics.

"[B]I prepared the all of the LEDs before starting to wire them by:[/B]

Bend the LED leads out in opposite directions
identify the flat side of the LED and cut off the other side to about 3/8"
Cut one side of a resistor wire down to 3/8"
poke both wires to be soldered into the flux
Pre-tin the wires by briefly touching them each to the tip of the soldeing iron with a small amount of solder on it
solder the resistor to the LED."

I then would work on one side at a time and I would:

slide on a 3/4" piece of heat shrink tubing
then cut the length of each side of the speaker wire so the LED wires could lay flat.
strip off 1/4" of insulation on each side of the speaker wire.
flux and pre-tin the speaker wire
cut the wires to the desired length on the resistor and LED
flux and pre-tin the wires.
then would solder the resistor side of the LED to the positive or red battery side of the wire
then repeat with the flat side of the LED wire to the black battery lead side of the wire
I would then cut the next 5" wire end lengths so the LED wires would lay flat making sure to maintain polarity
I would then solder it to the next 5" extension of wire and
slide on a 1/2" piece of heat shrink for the flat side connection.
I pushed the 3/4" heat shrink over the resistor and
the 1/2" heat shrink against the flat side of bulb
using a lighter shrink the heat shrink.

Last edited by arniep; Sep 14, 2008 at 07:44 AM.
Sep 13, 2008, 02:39 PM
Lee's Avatar
I agree with you and realize the rosin flux is the preferred solder to use because of the acid in the plumbers flux. It is what is recommended by the electronics industry as the best flux to use.


I have never had a joint or wire fail that has been soldered with the plumbers flux. Close inspection of many solder joints that are years old that were made using plumbers flux show no obvious solder deterioration or wire weakness. I have used this flux for hundreds if not thousands of solder joints

The plumbers flux is faster, makes less of a mess and sucks up the solder better than the rosin flux. Having both rosin core and plumbers flux side by side and using them on several different wires and repeating the tests before writing this entry confirms the plumbers flux gives what appears to be cleaner and more precise solder joints and doesn't leave the greasy mess on the soldering iron or the part and wire being soldered.


I updated post #18. Go ahead and use the rosin flux.

Last edited by Lee; Sep 13, 2008 at 03:06 PM.
Sep 13, 2008, 04:26 PM
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dbacon's Avatar
Maybe its a myth about the flux, I have never used anything but rosin on electronics, and it always worked well, but I have never seen corrosion on soldered pipes either.

The corrosion I have seen on wires is the dreaded black wire disease on older NiCad packs, and there never was any flux involved. I think it was thought to be the PVC insulation...

Does anybody have supporting data?

Wait, Lee does, I should have asked for data that supports the "don't use acid" side of the equation... Otherwise I would have to believe Lee.
Sep 13, 2008, 06:01 PM
Lee's Avatar
Here is a link that states what has been discussed.

"The choice of solder is also important. One of the things to remember is to never use acid core solder. Acid core solder will corrode component leads, board traces and form conductive paths between components. The best solder for electronics work is a thin rosin core solder. I prefer a thickness of 0.75mm, but other thicknesses will also work. Just remember not to get anything too thick."

I am not building circuit boards that may be etched by the solder and the fact that I haven't had trouble may be luck.

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