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Old Jul 27, 2010, 12:09 PM
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Devon,UK
Joined Nov 2002
255 Posts
aerial location

I am building a Polaris and would like to know the best location for the receiver aerial run. I am only a third of the way through the posts but have seen this subject raised somewhere. I am using a 35 crystal receiver, probably located behind bulkhead F3. I am using a carbon tube main spar and will be running the power cables down one side of the hull and was wondering if there is a best route to minimise interference problems. I am not keen to run the aerial out of the back due to prop location. Can someone give me a lead on this or point me to the previous discussions. Thanks in advance for your assistance.
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Old Jul 27, 2010, 12:24 PM
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USA, CA, Novato
Joined Jul 2008
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Originally Posted by AirmanAirhead View Post
Hey Kadil.... no wonder you've never built an F-22.. you keep dinkiing around here. Got any tape??? By now you must be a pro-Polaris flier AND builder!!

I'm in the process of repairing my one and only Polaris from a year ago. (with torque rods) I had pretty bad crash last time I flew it and just set it aside. The more I looked at it, the more I realized it was salvageable. So I'm in major repair mode. I was tempted to use tape... but decide glue might be better!

AA
woohoo, great news.

my polaris has been sitting since the rudder servo crapped out. can't stand cutting into this plane again but I suppose I'll have to get to it one of these days.
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Old Jul 27, 2010, 12:27 PM
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Originally Posted by rshep View Post
jetset44. does this type of wing construction (whole Polaris is balsa structure) change where the CG should be?


wow is that all balsa? awesome job!! careful with that plane!
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Old Jul 27, 2010, 02:06 PM
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rshep,

I really like that Polaris. Awesome job you've done. How much does she weigh? Love the color scheme too!

I have a limited aeronautical engineering knowledge, but, I would wager that your CG shouldn't change as long as your flying surfaces are the same size and in the same location.

The building material won't matter. The airfoil might have some impact but I'd suspect it would be negligible compared to a flat plate at the size of this plane.
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Old Jul 27, 2010, 02:34 PM
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Seattle, WA
Joined Jun 2002
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Originally Posted by rshep View Post
jetset44. does this type of wing construction (whole Polaris is balsa structure) change where the CG should be?
Nice looking model, shep. I can't quite tell what kind of airfoil this has, but if it's symmetrical the CG should be the same as the flat wing Polaris. If cambered, you'll probably need to move the CG forward a small amount if you didn't change the wing vs tail incidence angles.
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Old Jul 27, 2010, 02:54 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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Originally Posted by rshep View Post
does this type of wing construction (whole Polaris is balsa structure) change where the CG should be?
Is that a flat-bottom wing section? For safety I'd move the CG a bit forward of the standard location for the first flight, though in the end I'd expect it to be pretty close to the normal one. My experience has been that the model can tolerate a CG 1/2" or a bit more forward and still fly well (but is nicer on the spot).
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Old Jul 27, 2010, 03:39 PM
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Longmont, Colorado
Joined Jun 2005
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Pluggable Motor Connections

Finally found time to finish my first Polaris. Here is my hop up that provides a serviceable elevator servo and a clean way to manage motor wires that allows for motor swaps and up grades.

The motor is connected to standard 3.5mm bullet connectors with the wires soldered into the vent hole in the connector side. The soldered connector is then coated with three coats of Black Brush-On Electrical Tape made by BlueMagic Inc and available from Ace Hardware. It is pretty easy to paint the stuff on free hand.

The three female connectors in the nacelle are soldered to the speed controller wires that run down the vertical fin and are held in place by a small piece of ply. The holes in the ply were drilled to be a snug fit which held the connectors in place until they could be epoxied. I ended up coating the ply with black Sharpie and CA which would have been better done before it was installed. I used 14awg wires, but next time I may look at using 16awg to save weight.

Inside the nacelle, the wires drape neatly to one side of the servo control arm. I used a z-bend to attach to the arm. Not shown is another z-bend on the elevator. The two z-bend wires are roughed and "spliced" together near the elevator control horn with a small piece of hollow carbon fiber tube. If the push rod needs to be serviced, it is easy to crush the carbon tube with a pair of vice grips and pull the z-bend wires apart. If I was to do it again, I would probably try to drop the servo down a bit lower and use an EZ control rod connector on the arm. Also not shown is a foam hatch cover that gets taped in place over the elevator servo. I used tempered stainless steel wire for the control rods for rust resistance. They seem to have a more finished smoother surface than plain steel music wire. I'd also make the plastic tube that the control rod rides in a bit longer on the inside of the nacelle to make it easier to insert the z-bend wire.
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Old Jul 27, 2010, 04:01 PM
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Brisbane north, Australia
Joined Feb 2009
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Originally Posted by Daedalus66 View Post
No. I had one minor and two major misadventures caused by radio failure (see link).

http://www.rcgroups.com/forums/showp...postcount=6068

As well, a year of flying off not only grass and water but gravel, stubble fields, and the like has taken its toll. The old one will serve nicely as a test bed and trainer (right now it has an FrSky telemetry radio in it).
I guess that is about as much bite as I can hope for. If your capability as a pilot is anything like the knowledge you share on this forum, you are probably an excellent pilot.
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Old Jul 27, 2010, 04:12 PM
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Brisbane north, Australia
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Originally Posted by AirmanAirhead View Post
Hey Kadil.... no wonder you've never built an F-22.. you keep dinkiing around here. Got any tape??? By now you must be a pro-Polaris flier AND builder!!

I'm in the process of repairing my one and only Polaris from a year ago. (with torque rods) I had pretty bad crash last time I flew it and just set it aside. The more I looked at it, the more I realized it was salvageable. So I'm in major repair mode. I was tempted to use tape... but decide glue might be better!

AA
It has been a long time AA. In that time tape technology has advanced so much. Careful you might get left behind.

I myself am about to buy some foam board today for some new models. Featuring in these builds will be:
-concealed contol rods and torque rods (my own adaptation)
-main spar on the hinge line (I had no cautions when I first suggested this???)
-tape z hinges (thanks Tom)
-splash proof hatch (Thanks Mark)
-flush mounted, sealed esc, IN heatshrink (thanks Daedalus)
-........... and............TAPE (no thanks AA )

cheers,
Kim
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Old Jul 27, 2010, 05:36 PM
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Ontario, Canada
Joined May 2008
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OK gang, thanks for the responses ... I sure wish I was responsible for the construction of this plane but it was made by Al, a good friend of mine who has built from balsa for about 70 years. He was asked by me to build one so we could fly together at the lake. He didn't want to try the foam and produced this lovely balsa version.

umdpru, AUW is almost 28oz (covered with Century 21 fabric) and assembled with LePages waterproof glue.

jetset44, airfoil is a modified Clark Y (flat bottomed) with no change in wing vs tail incidence. She flies with CG at ~1" in front of the step (porpoised on grass) but here at the lake it seems to want to fly requiring a lot of up elevator. Do you think that instead of the 2 degrees it should be parallel to the wing?

Daedalus66, It handles well in the air (except for the elevator trim) after Al set low rates on elevator. Prior to that it was almost uncontrollably twitchy (Al's word). His 1/64" ply on the bottom (back to the step) has helped with his 3 (so far) pelican dives.
He has no middle "wing platform" and thus has a huge volume for his electronics installation (making me envious - mine is Performance board foam).
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Old Jul 27, 2010, 06:48 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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Originally Posted by MileHiFlight View Post
Finally found time to finish my first Polaris. Here is my hop up that provides a serviceable elevator servo and a clean way to manage motor wires that allows for motor swaps and up grades.
Some really interesting ideas there, including putting the elevator servo well forward where it can be accessed without messing up the stabilizer. I'd be inclined just to glue down the top, as I don't expect to have to service it, but I'd know that if I did it would be painless.

By the way, you're right, 16g wire is plenty.
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Old Jul 27, 2010, 06:58 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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Originally Posted by rshep View Post
jetset44, airfoil is a modified Clark Y (flat bottomed) with no change in wing vs tail incidence. She flies with CG at ~1" in front of the step (porpoised on grass) but here at the lake it seems to want to fly requiring a lot of up elevator. Do you think that instead of the 2 degrees it should be parallel to the wing?

Daedalus66, It handles well in the air (except for the elevator trim) after Al set low rates on elevator. Prior to that it was almost uncontrollably twitchy (Al's word). His 1/64" ply on the bottom (back to the step) has helped with his 3 (so far) pelican dives.
The CG sounds quite far forward and the need for up trim seems to confirm it. I'd move it back cautiously and use whatever trim is necessary to get level flight (don't worry about the stab setting for now -- if you end up with a lot of trim one way or the other you can adjust it later).

Make sure you are using moderate amounts of elevator (and some expo doesn't hurt) so you don't confuse overcontrol with lack of longitudinal stability. Also make sure the elevator linkage works smoothly and the elevator returns consistently to its neutral position -- hysteresis in the controls can look like instability too.

When you get the CG right, the model should be responsive in pitch but not twitchy. It should fly about level at medium throttle, not drop the nose much in turns, and transition smoothly into a glide without dropping the nose too much. With the flat bottom wing, you will, of course, get climb at full throttle. This is just the nature of the beast (you could use a mix to introduce a smidgen of down at full throttle but that would detract from the charm of flying such a model). If you go too far back with the CG the model will become very sensitive in pitch -- some people like this and use it to play in high alpha mode, but I like a more sedate setup.
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Last edited by Daedalus66; Jul 27, 2010 at 07:05 PM.
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Old Jul 28, 2010, 01:01 AM
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Brisbane north, Australia
Joined Feb 2009
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Paper on foam core board

I am getting to the stage where my scratch building skills are getting up there on par with the average scratch builder...maybe... .........with the exception of paper removal from (Quill) foam core board. I have successfully removed all the paper off 3 boards, the fourth is just so stubborn.

Also, by the time I pay for all that rubbing alcohol to loosen the glue, I may have well paid for hobby depron. Board is $10 each and it takes 2 bottles ($8 each) of rubbing alcohol for 4 boards. That adds up to $56 for 4boards of 800x500x5 depron (and only 3 were successful so far)

I am thinking of using a caustic or acid solution to eat the paper leaving the glue on the paper. This area has to improve. If any one in Australia has suggestions with locally available and affordable solutions, please share
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Old Jul 28, 2010, 01:10 AM
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United States, MA, Walpole
Joined Dec 2003
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Originally Posted by kadil View Post
I am getting to the stage where my scratch building skills are getting up there on par with the average scratch builder...maybe... .........with the exception of paper removal from (Quill) foam core board. I have successfully removed all the paper off 3 boards, the fourth is just so stubborn.

Also, by the time I pay for all that rubbing alcohol to loosen the glue, I may have well paid for hobby depron. Board is $10 each and it takes 2 bottles ($8 each) of rubbing alcohol for 4 boards. That adds up to $56 for 4boards of 800x500x5 depron (and only 3 were successful so far)

I am thinking of using a caustic or acid solution to eat the paper leaving the glue on the paper. This area has to improve. If any one in Australia has suggestions with locally available and affordable solutions, please share
WOW! Is that the only brand of foam board you can get there? Here it's about $3 for a sheet that size by a couple different manufacturers, and we also have some "dollar" stores that sell it for... you guessed it.... $1 a sheet!

I can usually get the paper off simply by soaking in water hot water for about 10 minutes or so, then peeling off the major layer of paper and "rolling" off the residue by rubbing with my fingers.
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Old Jul 28, 2010, 01:27 AM
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Brisbane north, Australia
Joined Feb 2009
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Originally Posted by Tom Frank View Post
WOW! Is that the only brand of foam board you can get there? Here it's about $3 for a sheet that size by a couple different manufacturers, and we also have some "dollar" stores that sell it for... you guessed it.... $1 a sheet!

I can usually get the paper off simply by soaking in water hot water for about 10 minutes or so, then peeling off the major layer of paper and "rolling" off the residue by rubbing with my fingers.
This is the cheap stuff over here (only because it is in the department stores)

Art stores have other brands for more money. And the glue thickness & quality varies.
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