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Old Jan 11, 2013, 09:32 PM
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Originally Posted by Lockey View Post
Great pics kingsflyer, I am envious .. wish we could get the Ultra in Oz

Thanks for sharing mate

Lockey
Just close yer eyes and click yer heals together.......
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Old Jan 11, 2013, 10:38 PM
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Even though doused in CorrosionX, I decided to keep my electronics off the floor in case of the eventual dunking and water sloshing around inside. Of course, all that goes out the window when flying inverted and attempting the inverted tail touch in water, which will probably pour all said water over my precious electronics
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Old Jan 12, 2013, 01:10 AM
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Glad you all enjoyed the pictures. I worked on my Ultra a little this evening. With the recommended weight motor (78 gm), my Ultra was very nose heavy. So I decided to change out the motor for something a little heavier and a little higher kV. With a new 100 gram motor, my 38 oz (RTF) Ultra will now balance with a 3-cell 2100 mah Lipo in the middle of the battery tray area. With the 3-cell battery, I'm getting 400 watts, or 168 watts/pound on a 3-blade 8x6 prop. I'm looking forward to trying this new setup in the morning if the wind holds off.

McD
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Old Jan 12, 2013, 08:32 AM
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hoping to maiden today also, wind fcst is 15-20 so will just have to hope the weatherman is wrong again!
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Old Jan 12, 2013, 09:36 AM
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Originally Posted by kingsflyer View Post
Glad you all enjoyed the pictures. I worked on my Ultra a little this evening. With the recommended weight motor (78 gm), my Ultra was very nose heavy. So I decided to change out the motor for something a little heavier and a little higher kV. With a new 100 gram motor, my 38 oz (RTF) Ultra will now balance with a 3-cell 2100 mah Lipo in the middle of the battery tray area. With the 3-cell battery, I'm getting 400 watts, or 168 watts/pound on a 3-blade 8x6 prop. I'm looking forward to trying this new setup in the morning if the wind holds off.

McD
That's odd because with the recommended 2810-9 motor and 3S 2200 pack I had to add 1/3 oz. of weight in the nose to get the CG correct!

Can you share what motor you are using now?

Scott

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Old Jan 12, 2013, 11:17 AM
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Very nice photos there Mike McD
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Old Jan 12, 2013, 03:14 PM
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Since I just totaled my XL, and my love for Polari is undying, the choice for me now is XL or ARF.
Is the foam on the ARF tougher than the depron?
I plan to add a light FPV set up to it. I suppose the XL would carry it better, but the ARF is smaller/easier to carry on a boat.
Decisions, decisions.
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Old Jan 12, 2013, 04:38 PM
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Originally Posted by Deadstick 8409 View Post
Since I just totaled my XL, and my love for Polari is undying, the choice for me now is XL or ARF.
Is the foam on the ARF tougher than the depron?
I plan to add a light FPV set up to it. I suppose the XL would carry it better, but the ARF is smaller/easier to carry on a boat.
Decisions, decisions.
It's hard to compare the foam. If you had a 6 mm sheet of each you would think Depron is stronger, but once the EPO is molded, I'd say the Ultra is a much stronger plane overall.

Scott
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Old Jan 12, 2013, 05:23 PM
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Depron is polystyrene based while EPO is expanded polyolefin. Styrene is a rigid brittle plastic, think disposable drink cups. PO is a cross between polythene and polypropylene, both ductile plastics. When you foam EPO in a mold you get a dense skin that is not as stiff as solid polystyrene's skin but it's much stronger.

It's interesting that EPP is pretty much the same foam but without the skin. Completely different behavior without the stiff skin.

Pete (a plastics engineer for GM in the day time)
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Old Jan 12, 2013, 10:27 PM
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Originally Posted by Petefoss View Post
Depron is polystyrene based while EPO is expanded polyolefin. Styrene is a rigid brittle plastic, think disposable drink cups. PO is a cross between polythene and polypropylene, both ductile plastics. When you foam EPO in a mold you get a dense skin that is not as stiff as solid polystyrene's skin but it's much stronger.

It's interesting that EPP is pretty much the same foam but without the skin. Completely different behavior without the stiff skin.

Pete (a plastics engineer for GM in the day time)
Thanks for the GREAT explanation, Pete! I've always wondered what the difference was.

Steve
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Old Jan 13, 2013, 07:48 AM
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Originally Posted by Model Aero View Post
That's odd because with the recommended 2810-9 motor and 3S 2200 pack I had to add 1/3 oz. of weight in the nose to get the CG correct!

Can you share what motor you are using now?

Scott

www.ModelAero.com
I'm now using an HK 3530 - 1400 style motor that weighs right at 100 grams with the prop adapter and prop. With this setup I can get 400 watts with the 3-blade 8x6 prop. I was able to balance the plane on the step with a 2200 mah 3-cell pack. I've been experimenting with moving the CG back a little at a time as the Ultra still seems to be flying nose heavy. The elevator has to be trimmed so that the top surface of the elevator is slightly above the top surface of the horizontal stab for straight and level powered flight and I need to hold some up for power off and landing glide. Still needs about half stick down for inverted flight.

These are not hugh issues, just trying to find a sweet spot for my style of flying. To me, the Ultra already flies much better than my original kit Polaris. The Ultra flies very stable when balanced on the step, I'm just pushing the envelope.

I've moved the CG back about 1/2" behind the step and the battery is now at he back of the battery tray again. I've ordered a 3536-1400 (120 grams) that I may try next.

McD
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Old Jan 13, 2013, 09:29 AM
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Got to the field yessterday and a forecasted, wind was 10-15 and bumpy.
I decided to fly anyway with 3S 2200 off grass.
Take off into the wind was no problem and graceful. Got up to speed and turned downwind and noticed a bit of wing wobble probably due to wind. She required quite a bit of up elevator for level flight. I trimmed ele up and made a few passes before landing. I thought CG or motor offset to flight axis were possible causes. I moved the lipo an inch back and it improved a bit but still required up elevator for level flight. I did have to shim the motor up (washers on the bottom 2 mount holes) to get it to align into the cowl hole perfectly, that may be my problem.... Got it trimmed and thought I would take her through a few more paces. Rolled 180 degrees and flew fine for a short while, then the pilot paniked and punched out! Punching out in a plane with the prop behind the pilot can be and was hazerdous. The cockpit took a prop strike but the pilot was not injured. When installing the cockpit, I always thought there was not a lot of force holding it in so I trimmed the front and back of the windshield to see if maybe it would seat better. That did not seem to help. I need to take a closer look at it. Was wondering if maybe I deformed the base when installing the windshield, and the magnets may not be getting as close as they shoud be, just a thought, need to look! Back to the hobby table.......fcst is no wind tomarrow, need to git-r-done!
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Old Jan 13, 2013, 09:54 AM
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A friend of mine replaced the canopy side magnets with ones that were twice as thick to get more hold down force.
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Old Jan 13, 2013, 10:11 AM
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Northwest Ohio
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Originally Posted by gatorb8 View Post
Rolled 180 degrees and flew fine for a short while, then the pilot paniked and punched out! Punching out in a plane with the prop behind the pilot can be and was hazerdous. The cockpit took a prop strike but the pilot was not injured.
Ouch!!! Well at least the pilot survived.

I'll let the manufacturer know about the magnets and have them use stronger ones next time.

Pete, thanks for the explanation of the foam differences. Very helpful.

Scott
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Old Jan 13, 2013, 10:12 PM
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charlotte, nc
Joined Sep 2003
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I got to log some data on the 2810-9 motor on 4 cell 2200 and an 8-4e prop. While the maximum watts was around 400, the ultra was crusing nice at about 200 watts and 9 amps. Three minutes of mixed flight used about 600 mah of battery. See data below.

The Ultra is flying great, but I had to move the battery way back to get it balanced on the step.

I do notice that it is bouncing a little left to right like the motor thrust is fighting the rudder trim. I'm sure this is covered in the threads. Can anybody give me a summary on solutions or point me to some key posts?

Scott, thanks for locating a red paint match. I touched packing tape to the fuse like Gater did. I have been painting EPO planes for a while and it is hard to get some paints to stick. I usually put on a coat of finishing resin to protect the paint.

Heres the 4 cell data.I will post 3 cell data tomorrow.
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