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View Full Version : Discussion 33% electric Ultimate Biplane, 19 pounds


blnk00
May 07, 2009, 06:02 PM
I had been looking for another large project when I ran across the Ultimate which nitroplanes has for $330.

http://www.nitroplanes.com/ul45giscrare.html

What really caught my attention is that it was tail heavy. The gas guys claimed they had to add 3 pounds in the nose just to make it balance. A light bulb went off in my head, PERFECT ELECTRIC! I was planning on using a123's which are heavier then lipos so a tail heavy plane was exactly what I needed.

The build was smooth and the plane has already flown 8 times. My setup:

-Turnigy SK 230kv motor from hobbyking.com
-two packs of 10 a123's in parallel to make 4600mah
-23x12 Xoar prop
-Sentillion 100amp 12 cell speed controller from hobbyking.com

I get a 70 amp draw with this setup. The plane flies but scale, not enough power for hard aerobatics. Stall turns, rolls, decent knife edge, that's about all you have power for with this setup. 5 minute flight. I went with this setup because I had everything at home already. Tried a 24x10 Xoar prop but she flies better with the 23x12.

She is still tail heavy. Even with the batteries placed in front of the firewall. I did not add have to add any dead weight however, wanted to keep her as light as possible. I have to tell you though, landing this thing is a joy. She settles in nicely and flares beautifully. Graceful in the air.

I am ready for more performance though so this is what I will be upgrading to:

-13 a123's
-Turnigy SK 170kv motor
-apce 24x12 prop

I ordered a Mastech variable power supply so that I can charge both packs together in 15 minutes. Who needs gas anymore when you can recharge every 15 minutes, I love a123's. During testing on my other planes I found that the apce prop gives me MUCH better performance then the Xoar props. The Xoar props give me more static thrust but the performance of the apce blows them away.

The quality of this plane is great and the wings are strong, well built. My only complaint is that the canopy came completely smashed in during shipping. I immediately called Nitroplanes and they told me that they have gotten many calls with the same problem on this kit and that they would send me a replacement when the canopies came back in stock. That was 2 over months ago. I've called 3 times since then with nothing. "We'll email you.." "We'll get back to you.." Nothing. Not even a record of the canopy order in their system. Ordering kits from nitroplanes sometimes is like russian roulette. And their customer service..

Let's just say you have a higher probability of making contact with a ufo then with a human at nitroplanes. I don't think I will ever order from them again because of this last experience but as for the plane itself, I am happy.

As for the canopy, I reinforced the inside with fiberglass and painted it black inside and out to cover the fiberglass work.

Will update this post with the performance gained using the upgraded motor and 3 cells.

NumbSkull
May 07, 2009, 09:49 PM
Beautiful looking plane!!

I'm anxious to hear how the 13S packs work out for you. I have a few 50CC sized electric setups that I would love to see in a bipe. I mostly fly 3D, so I would be very interested in how it flies inverted, and in harrier.

blnk00
May 08, 2009, 02:29 PM
Thank you buddy. Well I got the Mastech variable power supply today so chances are I will be doing the upgrade tonight. Hopefully I can fly her this weekend.

This power supply puts out 1000 watts so I can charge the 26 cells in about 14 minutes if I set it at 20 amps.

13 a123's is equivalent to about 11.6 lipos so I believe the power increase is going to be substantial. Considering she's still a bit tail heavy, the extra 6 cells in the nose should balance her out perfectly now.

Wildman777
May 08, 2009, 04:25 PM
Nice looking plane blnk! One of my buddies at the airfield has one of these flying on a DL50 gas engine. He's not to the 3D stage yet though so I haven't seen how 3D capable it is. I'm looking forward to more flight reports on yours as well.

blnk00
May 08, 2009, 06:02 PM
Thanks Dman. I'm dying to get out of work and get home to start working on it. Unfortunately, at the moment, I won't be able to give any technical data (amps, watts) after the upgrade because I switched the connectors from deans to bullet and I'm out of stock right now to switch out the connectors on the watt meter. These deans connectors were heating up pretty bad at 70 amps. After switching them to bullet connectors, no more problems.

lmopar69
May 08, 2009, 08:49 PM
What size bullets are you using on it?

Laine.

blnk00
May 11, 2009, 12:35 PM
4mm gold bullet connectors. They are great.

blnk00
May 11, 2009, 12:51 PM
I added the 3 cells on Friday for a total of 13 a123 cells. The plane flew great, more power. However, for the life of me, I don't understand how I fried both sets of 3 cells. This is the third time this occurs when running two packs of same capacity in series. In theory, you should be able to run let's say a 4 pack and a 5 pack of cells in series to make a 9 cell pack. Cells of same capacity and same brand. How would the 4 cell pack have a higher load then the 5 cell pack?

In this case I have a 10 cell pack and a 3 cell pack.

The only logical explanation is that the wire connecting both packs is causing a minimally higher resistance (even though I'm using thick 12 gauge wire) then the connectors between the cells. Whatever the reason is, in every scenario where I've used two packs in series of different cell count, the smaller pack heats up till destruction.

It doesn't make any sense but I give up trying to figure it out, it's costing too much. From now on I will only use two packs of equal cell count in series and if not, I will solder the smaller pack to the larger pack directly.

As for the biplane, I've upgraded to twin 14 cell packs. Ran a few tests through the speed controller and motor to make sure they can handle it, no problems with the apce 24x12. The sound of that prop spinning brings out the neighbors. Will have to wait till next week for a test flight. This is going to be a slow week.

Lynxman
May 17, 2009, 10:39 AM
Are you adding a 3S1P set or a 3S2P set? the rest of the pack is 10S2P right?

blnk00
May 17, 2009, 06:39 PM
I had a 3s1p connected to a 10s1p to make a 13s1p. There was no deans connector or bullet connector between the 3s1p and the 10s1p, it was a 3 inch 12 gauge cable soldered directly from one to the other.

Did the same with another pack to get two 13s1p's which I then connected in parrallel at the end to make a large 13s2p pack.

Lost the 3s1p on both 13s1p packs. I've also tried it in a different application with a single 13s1p, same thing occured to the smaller 3s1p.

In any case, I went ahead this time and soldered 4 cells directly to the 10 cell pack using copper tabs to get a 14s1p. Two of these in parrallel gave me a 14s2p. Worked perfectly. Didn't lose any cells and I flew the plane this weekend atleast 15 times.

blnk00
May 17, 2009, 07:12 PM
The best configuration for this plane is on an a123 14s2p. Plenty of power for sport aerobatics and fast on an apce 24x12. It feels like I'm flying my smaller .46 size Ultimate but on a much larger version.

Very happy with the upgrade. She flies 100% better now, there is no comparison. I couldn't get myself to leave the field. I can't stress how perfect this setup is on this plane.

With the added cells and the heavier motor, the plane is a little over 21 pounds. I'm getting about 25 pounds of thrust now, easy. If 3d is required I would put an apce 25x12.5 but you will be pushing 100 amps so the speed controller would need an upgrade, you'll need to add cooling fans and flights will be cut to less then 4 minutes. It's not worth it. Besides, she looks much nicer skimming across the field doing a low altitude knife edge.

Lynxman
May 18, 2009, 11:12 AM
Sounds great! :)

blnk00
Jun 03, 2009, 02:32 PM
I finally got some bullet connectors on my watt meter so I'm able to give power readings for this setup if anybody is interested.

Turnigy SK 170kv motor (hobbyking.com)
120 amp Sentillon speed controller (hobbyking.com)
14s2p a123 pack
apce 24x12

3500 watts clean, 3600 peak. Amp draw is 90-91 amps. This equates to a 20c draw from the a123 batteries which is nothing considering they put out 60c.

With the above setup you need to use atleast 4mm gold bullet connectors and 12 gauge wire. Try to keep the wire length as short as possible. I cut about a foot of wire from my setup and noticed a performance increase.

Also, do not test the motor for longer then a minute. It will overheat and the magnets will come off. I had about 15 five minute flights with the above setup, no problem. It took 1 one minute test run on the ground to dislodge a magnet on the motor. Epoxied it back on and let's see if it holds up. If not, I have a replacement motor on it's way while I figure out what glue I can use to affix the magnets back onto the inside motor casing.

Z06kal
Jun 03, 2009, 02:57 PM
I have an extra Turnigy SK 170kv if anyone wants one PM me I'll give it up cheap.

flystoolow
Jun 10, 2009, 12:15 AM
Use CA glue.

blnk00
Jun 10, 2009, 09:48 AM
Really? CA glue is strong enough or you just yanking my chain? Can it take the heat?

flyguide7
Jun 17, 2009, 07:34 PM
I have an extra Turnigy SK 170kv if anyone wants one PM me I'll give it up cheap.


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