XXL Polaris scratch build

[Otto Dieffenbach]

Will maiden tomorrow morning. Made out of 7 Chevy's take home containers.

[Larry3215]

Very nice!

That has to be about the smallest one Ive seen yet!

But - you cant get off that easy. We need more details! Motor? ESC? Batts? Servos?

You cut the tail off in the pic so I cant tell - elevons or seperate elevator and ailerons?

Your video guy will have fun keeping that one in the view finder I bet!

[Otto Dieffenbach]

The only mods to the original are 1) doubled the step to about 3/8 inch. I've found that on the micros you need more step because of water adhession. I have a micro P-82 built from two PZ P-51s on floats. 2) raised the motor a 1/4 inch for prop clearance. Otherwise standard setup. Motor is a APO5 3000kv,prop GWS 4.5x3, 7a ESC, 2s 350mah, AR6400 rcvr block up in the tail and two 1.5g spektrum servos for the ailerons. This was just a quick and dirty spy cam photo cause I was too lazy to get the good camera. Hopefully more tomorrow.

[Larry3215]

Good luck!

[Otto Dieffenbach]

Had 4 flights this AM. Flys great... stable and fast. See video and thread started in micros section of Wattflyer.

RC Micro Polaris XXS flown by Otto Dieffenbach

[Larry3215]

LOL

Outstanding!

[Otto Dieffenbach]

Thanx Larry, you turned me on to it. Very good flight characteristics but does not like inverted. Is the big one that way? A lot of elevator to keep the nose up, and I mean a lot. Also significant pitch changes with speed, not power but speed pitch changes. Nice addition to my water toys.

[Larry3215]

Ah! I forgot to mention that.

Thats mainly a CG issue. Im flying the big one way behind where Steve recomended the cg to be. I tend to like my models to be pretty close to neutral CG wise. That can make for a sensitive elevator but it really improves over all handling - especially the issues you are talking about.

If you do move the cg back, be prepared to move the step back as well or you can get severe porposing when landing at speed. if you remember in my water video that first landing at speed had multiple bounces. Thats due to the cg being well behind the step. When you hit the water, the weight pushes the tail down and causes the pitch up. Having the step further back reduces that or eliminiates it.

its not an issue if your flying the stock CG point - only if you move it back.

IIRC, I ended up about 4" to 5" behind where Steve recomended the CG to be. Thats equal to 2" behind on the original drawing. For your size - if Im doing the math correctly - that would be about 7/8" to maybe 1" behind the "stock" position if you started where Steve said to start.

I just measured and I moved the step back 4" on the XXL and I was going to move it back another 1/2" but didnt get around to it.

You need the step to be just slightly ahead of the cg. To far forward of the CG causes the porposing and to far aft makes it harder to rotate and harder maintain straight lines on the water or grass at speed. Its just like having the main wheels on a tail dragger in the wrong position.

[Otto Dieffenbach]

It flys so well upright I don't what to change it. Flew two flights in a Gym last night at 1/3 throttle, great low speed handling. Generally, I've found on the little ones that you need the extra stability due to gust/bumpy air. I am right at the suggested cg. I will try an experiment, move it back and check inverted behavior and elevator sensitivity.

[Larry3215]

Steve's recomended CG point is very nose heavy and therefore, very stable - which is exactly why you have the issues you are having.

As with most aero details - its a trade-off. To get what you want, you have to decide what you're willing to give up

You could go back in small steps.

I also use lots of expo to help with the sensitivity.

Keep in mind too, that I am using the ailerons as elevons PLUS a working elevator, so my big one has tons of elevator authority and is still a very stable flyer even at my rearward CG point.

I would move the cg back more if it wasnt too much trouble to get the packs further back

[surfer dude]

Originally Posted by Otto Dieffenbach

Had 4 flights this AM. Flys great... stable and fast. See video and thread started in micros section of Wattflyer.

RC Micro Polaris XXS flown by Otto Dieffenbach

Love it! It's so darn cute! Flys great!
I didn't hear, does it have an elevator, or elevons?
I've had the original kit version flying for over a year, and love it. I think I need to build that one.
Can you give us a snap shot of your plans, with dimensions if possible?

[Otto Dieffenbach]

Thanx. It does fly great even at low speed in a Gym. I have ailerons and elevator separate but will probably play with elevons and elevator per Larry's comments. Also I'll play with CG. But make no mistake this flys well as is but I'm an old pattern pilot and love being upside down so I will work to make that happen.

Larry, on my Sea Dart thread sent me a link to plans for the Polaris. I took this and scaled them down to a 13 inch wingspan. Only changes were to make the step 3/8" and to raise the motor pod 1/4 to a half inch to allow prop clearance. I mounted the AR6400 flat to the bottom of the stab and boxed it in after wiring and linkage connections. I mounted 2 1.5g servos flat to the wing under the fuse top. It takes 7 Chevy's containers to build. You can get one good flat 6" by 6" square out of each container. My prop, as indicated is a 4.5x3 GWS but I forgot to add that I cut it down to 3.75 inches. So it is a 3.75x3 prop. Best and good luck.

[Otto Dieffenbach]

I forgot to add that I started a Thread in the micros area with some pictures.

[Otto Dieffenbach]

First water flight of my micro Polaris. Need some suggestions on how to fix the s turning on takeoff. Best.

RC Micro Polaris XXS 1st Flight off Water flown by Otto Dieffenbach

[John_]

I'm thinking about getting the polaris for a sea plane. I saw one last week, and all the servos are buried in the foam. doesnt seem easy to get to servos, anyone rework this with hatches?

[Larry3215]

Its just as easy to cut the hatches later - IF you need them. It is a foam plane

If you cut them ahead of time, the chances of a leak are much higher.

[surfer dude]

Originally Posted by John_

I'm thinking about getting the polaris for a sea plane. I saw one last week, and all the servos are buried in the foam. doesnt seem easy to get to servos, anyone rework this with hatches?

I've been flying my Polaris for 3 years, never needed to see the servo's.
I put in good 9gm servo's, hxt900's, $3 servo's from Hobby King. They are cheap in cost, but I've used over 50 of these servo's, and never had one fail. I've striped them in a crash, but never in flight.
Larry's right, it's a foam plane, easy to make a hatch latter if you need it.
Not a single drop of water has entered my Polaris. The only hatch I have is my battery hatch which I tape all seams when flying off of water. The only other openings are the push rod guides, which I fill with grease to keep the water out.