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Old Aug 27, 2014, 01:57 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
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1000 coots scurrying off (they sort of run/fly along the surface).
What a wonderful sight! Super little birds, I think.

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Old Aug 27, 2014, 04:02 AM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Originally Posted by nickchud View Post
What a wonderful sight! Super little birds, I think.

They make a super big mess
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Old Aug 27, 2014, 08:53 AM
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United States, MA, Boston
Joined Jun 2006
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Originally Posted by Extreme Sports View Post
Thinking of using an NTM Propdrive 2836 - 2200KV that I have lying around, with a 7x6 prop, 50A ESC and 2200mAh Lipo. I've got to put in a larger ESC anyway, so I may as well size up for the larger motor and go the full hog with cooling techniques etc.

But I probably won't fly off water for a while....felt a bit bad disturbing the geese and there are no other suitable sites nearby (that I know of anyway).
I have found that Geese can be very teritorial and HATE my Polaris. All other waterfowl tend to ignore it.
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Old Aug 27, 2014, 11:18 AM
This is kid stuff.
Mazzepa1's Avatar
USA, AR, Harrison
Joined Aug 2010
849 Posts
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Originally Posted by umdpru View Post
I have found that Geese can be very teritorial and HATE my Polaris. All other waterfowl tend to ignore it.
I don't think geese even like each other.
Nobody else will hang out with them, so they flock up.
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Old Aug 28, 2014, 04:44 PM
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
16,172 Posts
Polaris vs. EX -- A Review

For the past few weeks, I've been flying the new Polaris EX, sometimes with EDF, but often with the standard Polaris motor (2212-6), 6x4 prop and 2200 3s battery. I have also been flying my old original standard Polaris with the same power package over this time. So my main purpose here is to compare the two prop driven versions of Polaris.

Building
Polaris EX is almost identical to Polaris, except for the tail, motor mount and servo installation. The main difference is that the EX eliminates the slightly challenging construction of the Polaris nacelle, instead mounting the motor on plywood struts above the rear fuselage. This allows an EDF unit to be substituted very quickly. It also shortens the motor wires and improves access to the servos, which are mounted from the top. The elevator servo is mounted in the fuselage instead of the nacelle, with a pushrod running through a curved tube set into the fin.

Flying
Polaris and Polaris EX fly almost exactly the same, except that EX tracks slightly better as a result of its twin booms giving more side area aft. There is no significant difference in weight when the same power setup is used -- both come out at about 21oz ready to fly with a 2200 3s battery. Both are wonderful flying machines and miles ahead of nearly all other models when it comes to water handling.

Crashing
Happily, as far as the EX is concerned, this is hypothetical! My expectation is that a stock EX might come out better than a stock Polaris in a minor crash, as the mass of the motor and elevator servo are not in the tail. On the other hand, if there is major damage, the twin booms and central fin of the EX might be a little harder to repair. I should point out, though, that it's very easy to reinforce the regular Polaris to make it much more resistant to tail breakage, so I don't consider the EX to have a huge advantage in this area.

Conclusion - propeller flying
The Polaris EX is very much in the Polaris tradition and an excellent addition to the line. There's very little to choose when it comes to flying, and both are straightforward to build, so you can safely choose on the basis of personal preference. I have to admit a soft spot for the classic Polaris look with its nacelle mounted motor, but I like the improved accessibility of the EX servos.

EDF
Of course, if you want to fly EDF, there's no choice. The EX is the only way to go and flies superbly with the new Lander fan unit. The higher weight (around 30oz ready to fly) has less impact than I expected and the fan provides more than ample thrust for high speed flight and vertical performance.

Of course, this requires a bigger battery with high C-rating and an ESC capable of true 60A performance. And flight time is 4-5 minutes instead of 7-9 minutes with a prop. But it sure is fun while it lasts!
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Old Aug 28, 2014, 10:11 PM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Originally Posted by Daedalus66 View Post
....Crashing
Happily, as far as the EX is concerned, this is hypothetical! My expectation is that a stock EX might come out better than a stock Polaris in a minor crash, as the mass of the motor and elevator servo are not in the tail. On the other hand, if there is major damage, the twin booms and central fin of the EX might be a little harder to repair. I should point out, though, that it's very easy to reinforce the regular Polaris to make it much more resistant to tail breakage, so I don't consider the EX to have a huge advantage in this area.....
Thanks for that summary.

It would seem to me that the plywood motor struts would be quite vulnerable in any more than a mild-moderate crash and that it might be a good idea to keep a spare set on hand. Clearly you aren't going to crash on purpose to test this, but will you let us know how they fare when incidents occur?
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Old Yesterday, 02:11 AM
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Nederland, ZH
Joined Dec 2011
624 Posts
Thanks for the comparision D66.

Last but not least there is the looks.
A matter of taste really.

The lack of an outboardmotor, the buildup of the single tailboom and the soft spot for the individual scratchbuild varieties determines my preference.

Good to hear from an expert that any Polaris is way ahead when it comes to waterhandling.

Talking about waterhandling: For what it is worth: In the otherwise boring second half of this video I tried to capture different taxiturns and short taxiruns. To see differences wingtip and aileron hydrodynamics and tight turns.

Best 1 second turns: on the beach pivoting on the step.
polaris77 (7 min 58 sec)
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Old Yesterday, 11:00 AM
Registered User
Switzerland, OW, Sarnen
Joined May 2014
66 Posts
hello everyone im in the process of scratch building my XL and was wondering which servos you guys recommend for this beast? thanks you very much.

great vid AK68. what an amazing lake...
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Old Yesterday, 06:37 PM
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
16,172 Posts
You need servos in the 11 to 16g range for the XL (some people use 9g servos, but I like a bit more power and gear strength). I generally use analog servos for these models and find them fully satisfactory.

One inexpensive servo that I've used with good results is this:
http://www.hobbyking.com/hobbyking/s...5kg_14sec.html

If you want higher precision and are prepared to spend more, here's a good choice:

http://hitecrcd.com/products/servos/...-servo/product

Don't jump to the conclusion that metal gear servos are necessary or even superior. Plastic gears wear less than metal and may give better precision. I find them totally adequate for elevator and aileron.

For rudder, however, metal gear servos tend to withstand landing shocks better when flying off ground. Here's one I've used:

http://www.hobbyking.com/hobbyking/s...ini_Servo.html

Something to consider with the XL is using two aileron servos. If your transmitter supports it, you can run them on separate channels and experiment with elevons coupled to elevator, flaperons/spoilerons, and aileron differential. Even if you just run them off a Y cable, you get a degree of redundancy. The XL can easily carry the extra 15g.

The precision of the elevator servo is particularly important for accurate trimming and smooth landings. Make sure yours works smoothly over its whole range before you seal it in.

If you are ordering inexpensive servos (like the $5 to $8 ones I've mentioned) always order spares to allow for the possibility of defects, crash damage, etc. If you buy from the LHS you can always go back for replacements or spare parts.

Servos generally resist water quite well except that they leak around where the cable enters. I seal this up with Goop or similar glue ever since I had a rudder servo half fill with water and cause a crash. You may also want to put some Vaseline around the output shaft. Just a little is adequate to repel any splashes.

Set up your linkages before you close things up so that 100% throw on the transmitter gives the control surface movements called for in the instructions. Then set low rate to 70% and use that initially. Don't set up huge throws mechanically and then dial down at the transmitter using end point settings or D/R as you will lose a great deal of precision.
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Old Today, 01:34 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,664 Posts
I've been scrolling back looking for plans of the XT. Are they available?

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Old Today, 05:26 AM
Registered User
Springfield, VA
Joined Feb 2000
1,151 Posts
Do you mean the XL? No, they aren't, but people just scale up the 100% Polaris to 133% if they don't want the kit. The differences between the XL and Polaris kits are basically proprietary info--Scott needs to give people SOME reasons to buy a kit
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Old Today, 10:01 AM
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
16,172 Posts
My only suggestions if you scale up Polaris to XL size (133%) or similar are:

Real 6mm Depron works well, but other material may need doubling in some areas for adequate strength.

I always add one or two extra bulkheads under the battery platform, and this is particularly important with the bigger versions.

If you use 6mm x 1mm flat CF spar material, as provided in the kit, then insert a second spar a few inches ahead of the main spar. Take a look at the kit manual to get the idea. Alternatively, you can use a more robust CF tube main spar.

Reduce the height of the top fin to just an inch or so to reduce the tendency of the model to flip when turning cross wind in a stiff breeze. Or just learn to "sail" the model backwards without turning down wind after landing. By stiff, I mean anything over about 10-12 mph.

But the best idea is to buy the kit, thus getting real Depron ready cut, as well as the spar material.
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Last edited by Daedalus66; Today at 11:57 AM.
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Old Today, 01:39 PM
Registered User
Switzerland, OW, Sarnen
Joined May 2014
66 Posts
Great info deadalus thank you very much

Quote:
Originally Posted by Daedalus66 View Post
You need servos in the 11 to 16g range for the XL (some people use 9g servos, but I like a bit more power and gear strength). I generally use analog servos for these models and find them fully satisfactory.

One inexpensive servo that I've used with good results is this:
http://www.hobbyking.com/hobbyking/s...5kg_14sec.html

If you want higher precision and are prepared to spend more, here's a good choice:

http://hitecrcd.com/products/servos/...-servo/product

Don't jump to the conclusion that metal gear servos are necessary or even superior. Plastic gears wear less than metal and may give better precision. I find them totally adequate for elevator and aileron.

For rudder, however, metal gear servos tend to withstand landing shocks better when flying off ground. Here's one I've used:

http://www.hobbyking.com/hobbyking/s...ini_Servo.html

Something to consider with the XL is using two aileron servos. If your transmitter supports it, you can run them on separate channels and experiment with elevons coupled to elevator, flaperons/spoilerons, and aileron differential. Even if you just run them off a Y cable, you get a degree of redundancy. The XL can easily carry the extra 15g.

The precision of the elevator servo is particularly important for accurate trimming and smooth landings. Make sure yours works smoothly over its whole range before you seal it in.

If you are ordering inexpensive servos (like the $5 to $8 ones I've mentioned) always order spares to allow for the possibility of defects, crash damage, etc. If you buy from the LHS you can always go back for replacements or spare parts.

Servos generally resist water quite well except that they leak around where the cable enters. I seal this up with Goop or similar glue ever since I had a rudder servo half fill with water and cause a crash. You may also want to put some Vaseline around the output shaft. Just a little is adequate to repel any splashes.

Set up your linkages before you close things up so that 100% throw on the transmitter gives the control surface movements called for in the instructions. Then set low rate to 70% and use that initially. Don't set up huge throws mechanically and then dial down at the transmitter using end point settings or D/R as you will lose a great deal of precision.
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