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Aug 20, 2019, 06:33 AM
Registered User
FWIW, the XL was 133% of the Polaris, and the kit plans to my knowledge were never posted. 150% is actually the size of a North Star. In general, the larger the Polaris the more sedately it flies--they become more and more a floater unless you decide to hop it up. You can always go to a larger/more powerful motor, but then you have to beef up the motor mount, add reinforcement to the pylon/fuselage, extend some doublers/braces, etc. All depends on what you are interested in...Pete M
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Aug 20, 2019, 07:25 AM
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pmdevlin's Avatar
My current Polaris (it's the 4th) is 120%
I was expecting same performance as standard size, just bigger! My previous ran on 4 cells so I moved everything over to the 120% which proportionally was a lot lighter but the end result was slower but can fly a lot more stable.
I'm sure there is an explanation for this!
Aug 21, 2019, 04:00 AM
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pmdevlin's Avatar

interesting take off!


some after quite some time, well over a year, I thought it was time to get the Polaris out. My RC Plane interest have started to lead to EDF, which is a new chapter to me, and the Polaris is an excellent platform to practise with! (And I was never that good at it!)

So, control surfaces checked, all appeared to be ok, and off I go. Flying off salt water certainly is a risk, but the scenery is to die for, and unusually ona day off work, 7.30am, tide is out, no wind, perfect! until I try and take off

depron scratch built Polaris RC waterplane (4 min 47 sec)
Aug 21, 2019, 04:14 AM
Youtube channel : solentlifeuk
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You're not only one to have that ... it only needs one sponson to dig in and WOOP's .... its one of the major reasons choppy water can flip them.... other than wind getting under one wing.

Sand ? Very abrasive but because of SW and its terrible effects on gear - I think I would have found an area of sand to take off from.
Aug 21, 2019, 05:32 AM
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pmdevlin's Avatar

rusty thumbs sorted out!


yay!

successful take off, but need more speed

Polaris leasowe beach 2 (5 min 11 sec)
Aug 21, 2019, 05:37 AM
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pmdevlin's Avatar

Need for speed!!


Quote:
I would have found an area of sand to take off from.
Just couldn't resist the call of the water!!

Ok guys, need some solid advice here,

I'm running 4 cells, ok, they are getting tired but all 3 packs delivered similar performance. Ages ago, I removed the prop it had, and it was a while before it was replaced, it might be wrong

From half throttle, I'm not going any faster, it just gets a lot noisier!. I want speed, I have torque, as can be seen by the large loops in the second video that are well into the battery use. I'm running an APC 8x4, with NTM (hobbyking) 28-36 1400kv propdrive motor, this is now 5 yrs old and has spent most of its use at a beach, or on water, so maybe this is getting on a bit?

Don't really have much more room for a larger diameter prop without surgery to move the motor mount up, do I need more pitch, or less?, or is it time for an overhaul

Ta
Paul
Aug 21, 2019, 05:38 AM
Youtube channel : solentlifeuk
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My sponsons are now taped on with cocktail stick alignment !! I've caught them so often in grass etc. - they snap off and eventually I end up using GF tape to secure.
The sticks give them rigidity to stand up to water, grass etc. ..
Aug 21, 2019, 05:56 AM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by pmdevlin
Just couldn't resist the call of the water!!

Ok guys, need some solid advice here,

I'm running 4 cells, ok, they are getting tired but all 3 packs delivered similar performance. Ages ago, I removed the prop it had, and it was a while before it was replaced, it might be wrong

From half throttle, I'm not going any faster, it just gets a lot noisier!. I want speed, I have torque, as can be seen by the large loops in the second video that are well into the battery use. I'm running an APC 8x4, with NTM (hobbyking) 28-36 1400kv propdrive motor, this is now 5 yrs old and has spent most of its use at a beach, or on water, so maybe this is getting on a bit?

Don't really have much more room for a larger diameter prop without surgery to move the motor mount up, do I need more pitch, or less?, or is it time for an overhaul

Ta
Paul
You have a standard Polaris ?? With 1400kv and 8x4 ? Even on 4S - that's a strange combo for a Polaris unless its a bit larger than the standard version.

Usual setup is 2836 2200kv with 6x4 (I now run 6x4.5 Bull prop) 2 or 3 blade prop on 3S. Its not exactly fast - but its not slow. Some people run 7x4 on these - but then you get into prop clearance factors.
I had a lot of success with 6x5 APC style prop ...

I know a guy who runs 4S on his 6x4 and 2200kv .... but when I tried - my motor ran hotter than I care for.

First ... diameter does not give speed - it gives acceleration ... Speed comes from pitch. So your 8x4 is getting you up to flight speed quickly but pitch at 1400kv is maxing out early.

You have options :

1. Drop back in diameter and up the pitch. This then allows you to stay in similar amp / watts load on battery / motor / esc.
2. Replace motor with higher KV but to be safe - drop back in diameter but keeping same pitch. Again trying to keep amp / watts load similar.

I use a simple rough reckoner :

KV x Pitch x Battery S ...

You have 1400 KV, 4 pitch and 4S ... this gives : 22400 factor

Your speed is based loosely on that factor - so you need to increase factor by playing with the numbers while keeping all others factors same.

ie - lets say you decide to up pitch ... 1400Kv x 5 pitch x 4S = 28000

but you could have similar by reducing battery S and adjusting other :

ie - 2200KV x 4 pitch x 3S = 26400

But an 8x4 is too much for a 2826 2200kv motor.

eCalc is your friend here ... to find the prop / motor / battery combo ......

(I know some will laugh at my KV x Pitch x Battery reckoner ... but as a hobbyist - I look for practical ways to arrive at possible combo's).
Aug 21, 2019, 10:49 AM
Retired CAD guy
birdofplay's Avatar
As mentioned a few post back , I have thrown my efforts into the 150% project.
Here are some pix of intermediate build results showing parts, orientations and fit up.
I am using Gorilla White for parts assy and Gorilla Clear for CF spar installation.

So far no issues with fit-up.

I plan to add a little THIN PLY to certain critical Tail connection areas and the motor mount.

If the wing proves to be too flexible I may simply add a KF section/doubling on the top or maybe the bottom, hmmmm .... ?

More L8r

Bob @ Hoosier Cutout Service

Those pix ALL were looknig great in my File Manager view as well as the Pic Viewer.
Why they are 90 deg CW in RCG is a mystery to me.
Last edited by birdofplay; Aug 21, 2019 at 10:56 AM.
Aug 21, 2019, 06:02 PM
Registered User
pmdevlin's Avatar
I'll read all your info again nigel to digest it mine is a 120%
That combo worked very well on a standard size so yes its speed I want
Thanks
Paul
Aug 22, 2019, 02:59 AM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by pmdevlin
I'll read all your info again nigel to digest it mine is a 120%
That combo worked very well on a standard size so yes its speed I want
Thanks
Paul
I would suggest getting a 28 size motor of over 2000kv .... stick a 6x5 or the 6x6 racing prop on ...

Battery of 1800 to 2250 in 3S ...
Aug 22, 2019, 05:08 AM
watch your head
Quote:
Originally Posted by pmdevlin
some after quite some time, well over a year, I thought it was time to get the Polaris out. My RC Plane interest have started to lead to EDF, which is a new chapter to me, and the Polaris is an excellent platform to practise with! (And I was never that good at it!)

So, control surfaces checked, all appeared to be ok, and off I go. Flying off salt water certainly is a risk, but the scenery is to die for, and unusually ona day off work, 7.30am, tide is out, no wind, perfect! until I try and take off

https://www.youtube.com/watch?v=UvxUlaoFl8c
As far as i can see, you are missing one of the swimmpontons. So maybe that causes the bad starts?
Aug 22, 2019, 06:12 AM
Registered User
Agreed. I did not see that when I watched the video (I skipped to the takeoff), but that would definitely affect the takeoff--the side with the pontoon would cause more drag, cause the other wing to lift a bit letting more air get under it, and spin the model out, just like the video shows...Pete M
Aug 22, 2019, 06:53 AM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by van3st
As far as i can see, you are missing one of the swimmpontons. So maybe that causes the bad starts?
He says in the video that he lost one sponson ...

Yes the model veers towards the one sponson remaining ...
Aug 22, 2019, 08:07 AM
Registered User
pmdevlin's Avatar
At least it proves the wing floats actually have a purpose!
Not convinced 3 cells will push this larger scale Polaris faster nigel, cheapest option will be to experiment with props but as the bats are old that's another consideration I suppose


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