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Old Mar 14, 2011, 01:00 PM
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United States, TN, Jackson
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Originally Posted by Dangaras View Post
Someone asked me for a diagram of the electronics with multiple parallel lipo packs, here it is.
How would you do this if you don't use a separate BEC???...Do you have to cut one of the red wires on one of the stock ESC's???...I've had many electric models but this is my first electric twin...

Kevin
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Old Mar 14, 2011, 01:22 PM
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Owatonna MN 55060
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Mine flew fine with counter rotating GWS HD 9X5X3. No cowl changes. Not stock motors.
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Old Mar 14, 2011, 02:08 PM
Dont be divided from the truth
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Canada, ON, Toronto
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Quote:
Originally Posted by Kevin Greene View Post
How would you do this if you don't use a separate BEC???...Do you have to cut one of the red wires on one of the stock ESC's???...I've had many electric models but this is my first electric twin...

Kevin
Kevin,

what dont you understand??? Look at the diagram, read the text. It explains exactly what is required.
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Old Mar 14, 2011, 02:48 PM
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Los Angeles
Joined Feb 2004
376 Posts
Guys,

I got this little gem at the AMA show a few months ago. I could not conceive trying to fit it into my Flex with 10 other planes while in one piece. This thing is bulky and fragile. No worries. I put 2 carbon (front and back) spars in the center that separate with a few magnets in the main fuse to hold the joint together. The tail booms I added a tab of ply and use some quick release pins to hold the tail together. It holds together just fine in the air (many flights now) and easily comes apart and goes together. If any one wants more pics and details, no problem, just ask. I donít know if it can be done to an already built P-38, but for the guys who want to put it together with this mod in mind, it's worth it.
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Old Mar 14, 2011, 04:27 PM
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Monahans TX
Joined Sep 2010
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Quote:
Originally Posted by Kevin Greene View Post
If you do counter rotating props you do know that you will have to change the right motor mount drastically, don't you???
I sure do...it's going to take some work on my part.
My thoughts are that both motor mounts will need to be altered.
The reasoning is that with the props rotating the same direction, a small amount of right angle is used on both.
I could use the exact opposite angle on the other side, but that wouldn't accomplish anything but a loss of thrust.
The motors themselves will counteract their own torque, no need to add even more countermeasures.

Some would argue that an engine out will benefit from the way it's set up now, but after two engine outs I have experience that says otherwise.
When you lose an engine, there is no go-around with partial throttle and lots of opposite rudder.
You chop the throttle right then and dead stick the rest of the way.
This P-38 simply won't fly with that much differential thrust, no matter how much built in angle you have.
...well, practical angles anyway
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Old Mar 14, 2011, 05:00 PM
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"When you lose an engine, there is no go-around with partial throttle and lots of opposite rudder.
You chop the throttle right then and dead stick the rest of the way."

I agree. Although I have not tried to fly it on one engine. I lost one, killed the power (to both), hit throttle hold so I would not accidentally advance the power on the good engine, then landed safely (oddly enough, one of the best landings I have ever made).

It might be interesting to try flying on one engine at high altitude (assuming one sets it up to be able to cut only one engine).
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Old Mar 14, 2011, 05:13 PM
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Monahans TX
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Tried it with my last few flights, it's impossible to control.
I use the three position switch to disable the throttle/rudder mixing and use the throttle hold to shut one engine off.
That way I had the ability to use opposite rudder to counteract torque.
It was way worse than differential thrust and I almost didn't pull out of the spin because I accidentally hit the rudder d/r switch thinking it was the throttle hold while trying to fight it.
With the differential thrust set up at full throttle, the opposite engine doesn't completely shut off but rather only goes to about 50%.
Even at that, holding knife edge flight with full aileron deflection it lost altitude and eventually nosed up in knife edge attitude and went into a spin.
Once you get into a spin with one engine going, there's no getting out unless you chop the throttle and have the altitude to recover.
Low throttle settings aren't quite as bad in terms of yaw, but remember that half throttle with an engine out is like having 1/4th the thrust.
With little propwash and low airspeeds, the rudder loses effectiveness.
You won't have enough power to sustain level flight, and if you try to hold it up to reach the field it'll stall and enter a spin.
Any which way you look at it, losing one motor effectively means you just lost both.
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Old Mar 14, 2011, 05:28 PM
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United States, TN, Jackson
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Originally Posted by Dangaras View Post
Kevin,

what dont you understand??? Look at the diagram, read the text. It explains exactly what is required.
You've been a smart aleck to me now on two posts...Listen---The pic shown has a separate BEC...How are the motors wired WITHOUT THE SEPARATE BEC...Why don't you read my question THROUGHLY before giving a knee jerk smart aleck response....Better yet, Don't respond to me at all and let someone else that wants to teach someone how to do something instead of being a smart aleck.......

Kevin
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Last edited by Kevin Greene; Mar 16, 2011 at 05:15 PM.
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Old Mar 14, 2011, 05:32 PM
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Owatonna MN 55060
Joined Sep 2005
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Quote:
Originally Posted by Kevin Greene View Post
You've been a smart a$$ to me now on two posts...Listen---The pic shown has a separate BEC...How are the motors wired WITHOUT THE SEPARATE BEC...Why don't you read my question THROUGHLY before giving a knee jerk smart a$$ response....Better yet, Don't respond to me at all and let someone else that wants to teach someone how to do something instead of being a smart a$$ jerk off like yourself.......

Kevin
How many servo's are you using in yours? I don't think one stock ESC will run all 10 the RTF comes with.
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Old Mar 14, 2011, 05:46 PM
Dont be divided from the truth
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Canada, ON, Toronto
Joined Mar 2010
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Quote:
Originally Posted by Kevin Greene View Post
You've been a smart a$$ to me now on two posts...Listen---The pic shown has a separate BEC...How are the motors wired WITHOUT THE SEPARATE BEC...Why don't you read my question THROUGHLY before giving a knee jerk smart a$$ response....Better yet, Don't respond to me at all and let someone else that wants to teach someone how to do something instead of being a smart a$$ jerk off like yourself.......

Kevin
Looks like you need to relax & stop being the local jack, this is a hobby. Dont have BW to respond from phone. Answer question asked & will get you the answr, better yet maybe you shld find anothr hobby, this one's not workng for you.

There is more than one post that indicates people are moving towards a separate BEC as the single or even double ESC BEC wont meet the needs of the servo loading.
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Last edited by Dangaras; Mar 17, 2011 at 09:31 AM.
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Old Mar 14, 2011, 07:25 PM
add lightness
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Big time Minneapolis, Good Ol' St Paul
Joined Oct 2007
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I highly recommend you run a sep. UBEC. they are like $6-$8 (you don't need to use a $20 CC 10amp). just like a 5-6 amp UBEC.
There are 10 servos on this plane and it's a twin, so I'd use one. it's no fun when too much load overloads your built in BEC and your flying along and suddenly you have NO control and it goes in. going to be a lot more work and $ to fix it and it won't look as good as new.
get a UBEC.

also, I pull the red wires from both escs, not just the wire to the radio. as in, do not connect the red wires from the two esc's together.
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Old Mar 14, 2011, 08:27 PM
as much as I can
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NZ
Joined Jan 2010
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I'm having a problem understanding why you can't run the two linear BEC's in parallel. They do it in the ESC's BEC anyway (multiple 5V regulators in parallel).

Are people having problems with this kit, when using both BEC's in parallel? Probably just a large capacitor (4700uf), would be all that is needed.
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Old Mar 14, 2011, 09:51 PM
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Monahans TX
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I'm having a problem understanding why the factory setup is inadequate for you guys.
Never once had a problem with it and I use max throws on all my controls.
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Old Mar 14, 2011, 09:53 PM
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Last edited by Kevin Greene; Mar 17, 2011 at 11:04 AM.
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Old Mar 14, 2011, 09:54 PM
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United States, TN, Jackson
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Quote:
Originally Posted by WestTexasKing View Post
I'm having a problem understanding why the factory setup is inadequate for you guys.
Never once had a problem with it and I use max throws on all my controls.
DITTO!!!!

Kevin
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