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The World Models Paulistinha P-56

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Old 04-25-2012, 06:01 PM
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DeaninMilwaukee
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Default The World Models Paulistinha P-56

I bought The World Models Paulistinha P-56 over a year ago with the intention of converting it to electric power and flying it at a couple of electric events last summer. I really like cubs in general and wanted to do a 40 class one. I saw an ad for it in a model aviation magazine and both liked its unusual looks and the fact that its was fairly light for a scale 40 class cub, making a good electric conversion.
The basic build was simple and routine, it was the electric conversion that got a bit fussy. While the motor mounting was no problem using a gp mount and a BP 3520-6 motor, the battery placement for balancing, plus how to mount and access the batteries was much harder.
Long story made short, the plane didn’t get done on time and wound up getting shelved until recently when I got motivated and finally got it done.
Since I didn’t want to cut up the cowling, that meant that the battery had to be in the cockpit area. Even by placing it on end andflat against the firewall, it was still tailheavy, so I added a second battery to make it balance. I am using velcro to hold them in place, and have made them accessable by making the windshield removable.
Running up the motor, my batteries held a solid 14.4v under load, ( a benefit of only drawing them at around 7.5c) which gave me 40 amps and 575 watts into the apc 12-6e prop. The balanced prop was very smooth, and pulled the plane forward about like you would expect from a 40 size glow motor. The plane came up right at 5lbs without the batteries, and 6lbs 3 oz with, for about 92 watts per lb.
I am excited that this plane is finally done and am hoping to get it airborn this weekend, and will post about how it went.
Dean

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Old 05-08-2012, 12:35 PM
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VinceHerman
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Default RE: The World Models Paulistinha P-56

Hi Dean,
How did the maiden go?
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Old 05-08-2012, 02:12 PM
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DeaninMilwaukee
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Default RE: The World Models Paulistinha P-56

Stiil hasn't.

The weather and my offdays haven't been cooperating at all. I am hoping to get it up tommorrow before work.

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Old 05-10-2012, 05:38 AM
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DeaninMilwaukee
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Default RE: The World Models Paulistinha P-56

I finally got to fly my The World Models Paulistinha P-56 after 2 weeks of waiting for decent weather and time off from work to coincide.

A storm front had just moved through, so the fields slightly long grass was completely saturated, and I knew this would make takeoff and landing tougher as the plane couldn’t roll as easily through this as it should. I was worried that the plane might try to nose over instead of taking off, but once it got moving it actually took off easily and was airborne at around 1/2 throttle in around 50 ft or so.

On the first flight, there was some significant and slightly gusty wind coming across the field at 45 degrees from the runway angle, so I was a bit nervous trying any risky moves and worked into them gradually. Trimming was not too bad. I had to correct a slight tendency to roll left and found that the throttle to down elevator mix I assumed I needed prior to flight wasn’t needed after all. The power was good with a fast climb at around 45 degrees as high as you wanted to go, but true vertical would run out of steam after 100 ft or so. After 7 minutes, I did one practice pass for landing and then did the real thing. It was controllable and greased right in untill the wheels actually touched down. Thats when the extra drag of the deep wet grass made the plane act like it had wheel brakes and the plane did a slow drawn out nose over that finally went over onto its back right as it came to a halt.

There was no damage at all so after an inspection and a battery swap I went up again.

This time the winds were a little more challenging, but now the plane was trimmed and the throttle elevator mix was removed. I did some basic aerobatics including some very nice looking stall turns, some tight and very large loops, and a little bit of inverted flight, all of which it handled well. I found that the plane would fly comfortably at 1/2 throttle even with all the wind and had quite a lot of power in reserve. Prior to flight I had been worried that the plane might have a tendency to tip stall due to it carrying the extra 10 oz battery, but it turned out to be a non issue. I did all sorts of slow, very tight turns using full rudder like you would do with a 3D plane, and it never once even hinted at dropping a wing. After 8 minutes, I again went in for the landing. I put it down a little too fast this time, bounced a bit and again, due to the wet grass, it acted like the brakes were on. This time however it merely tipped up on its nose as it stopped and didn’t go over completely.

At home, my batts all had around 3.8 volts per cell, and took 2.023 mah back into the first set and 1.982 mah into the second set of the 5300 available. This means my 8 minute flights used a bit less than 1/2 of the available juice, despite fighting the winds. In calm weather and just cruising around I should have no problem at all doing 15 minute flights.

Overall I am quite pleased at how the plane flies. It handles well using the recommended throws, has good power and flight time, and frankly looks great just flying by. I am expecting to have a lot of fun with this one this summer.

Dean

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