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Author Topic: Electrocuting the Atlantis  (Read 9220 times)

Offline Randy Powell

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Re: Electrocuting the Atlantis
« Reply #150 on: October 30, 2020, 09:03:18 AM »
Tim,

I've retrofitted 2 gas powered planes to electric. As noted by many, the trick is to be sure you route enough air over the electrical bits. And also, set things up so that doing things like changing batteries isn't too onerous.
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Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #151 on: November 01, 2020, 05:12:55 PM »
Well crap!  I fried the motor.  I went out to fly today and the thing just buzzed and tried to move, but didn't.  The ESC did manage to turn an eFlight Power 15 just fine, so it's not that.

I should have noticed that the motor feels like it's got a shorted turn -- the bearings feel fine, it turns OK if you turn it slowly, but it doesn't want to spin fast.

It probably overheated, either because it was marginal in there (which I knew) and the extra load of a wire rubbing on the thing pushed it over the edge, or it's because the motor was just too dang small.

I can't know unless I go and do the same thing again.

I think I'm going to buy a 35mm motor & see if I can shoe-horn it in, and another 2826/12, and see if it'll last (and hope it doesn't cut out at the top of a loop).  I may tear down the one I have, just to see how bad it looks inside.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #152 on: November 01, 2020, 05:18:00 PM »
Or maybe a Badass 2826 -- it looks like that may be a viable choice, and they're certainly rated for higher power.  Of course, if I'm just cooking the motor that may not make a difference.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Paul Walker

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Re: Electrocuting the Atlantis
« Reply #153 on: November 07, 2020, 11:07:46 PM »
  The ESC did manage to turn an eFlight Power 15 just fine, so it's not that.

[/quote]

A power 15 is a bunch too small for that plane Tim. I was using an E-Flite 32 for that size airplane.

If you can't spin the motor freely, you burned up the windings.
It's toast!

OK, just went back and re-read your previous posts. It was not an E-flite 15 flying the plane. Never mind about that point!

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #154 on: November 10, 2020, 10:31:25 AM »
My Power 15 would bolt right in there, and fly the plane just fine.

Briefly.

At least I think it wouldn't fry until I was in the air.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #155 on: June 19, 2021, 04:02:11 PM »
Well, it's getting a Badass 2826.  Last time I installed the motor as close as I could to the front, cut off the end of the shaft, and sacrificed some cooling.  This time out I'm installing the motor so that the "stock" shaft length puts the spinner where I want fore&aft -- that moves the motor back about 3/16 of an inch.  I'll work on the cowl to get some air in there.

Also, last time out I routed the air so that it just sort of blew on the bottom front of the motor -- there was a baffle in there so that any air coming in had to go through the motor, but clearly it wasn't effective enough.  This time there's, like, holes.  I'll probably do some flights with the spinner off, then compare-contrast the motor temperature with spinner on and off.

I won't be getting appearance points for it, so aside from some inevitable comments from Paul if I make it too ugly, it's not like I'll lose anything if I bias the the cooling vs. looks fight in the direction of lower temperatures.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #156 on: June 19, 2021, 05:07:50 PM »
My usual go-to clamp when nothing else works is tape.  Someone, however, has apparently waxed this airplane a bazzilion times, not to mention letting a motor slobber castor oil all over it.  So things are wedged in place with balsa, matchsticks and (yes) Q-tips.

It'll hold until the glue sets.  Unless a moth lands on it.  A mouse running over it would definitely upset the thing.  For a mount that was put in place by fittin' and filin' the thing fits pretty good.  I'm just lining up the spinner to the front of the fuselage -- it's offset about .02" to inboard, but I think I'll accept that (no appearance points!)
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #157 on: July 25, 2021, 05:52:27 PM »
I added an outlet just for motor air, and I managed to fly yesterday and today.

With just the outlet, the motor was cooler than the Cobra, but still hot enough to be worrisome.  Based on advise from Paul Walker I added some NACA-ish inlets to the side of the cowl, blowing on the motor.  While I was adding the inlets, I noticed that I had failed to modify the baffling from the existing front scoop to match the new motor position -- so I fixed that, too.

This brought the motor temperature down to somewhere in the neighborhood of 50C.  This is according to a phenomenally cheap Harbor Freight thermometer -- so I'm not sure I believe it.  But the measurement is backed up by calibrated fingertips -- I can touch the motor and hold my finger on it, which is about 50C.  Moreover, it starts cooling immediately after the flight, where the Cobra would continue to heat up on the outside of the motor, indicating that it was _really_ hot inside.

I decided that my attempts at NACA inlets were ugly, so I made metal covers for them.  Hopefully these will generate even more airflow over the motor -- and they'll definitely cover my woodworking sins.  More testing as I get a chance.  I'm hopeful that I can start actually practicing flying with this thing, rather than just piddling with the power system.

At this point I'm going to do a few more test flights to check temperature, then start actually flying.  I have a spinner that Howard Rush made for me to fit my backplate, but I haven't yet assembled it.  I'm a bit concerned that it will block some of my cooling air, so when I do get that done I'll be testing it, and then I may end up making some holes in it for airflow.

I did expect that I'd have a learning curve switching to electric.  I did not expect that it would be this steep and this high at the beginning!
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Dennis Nunes

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Re: Electrocuting the Atlantis
« Reply #158 on: July 25, 2021, 06:31:38 PM »
I did expect that I'd have a learning curve switching to electric.  I did not expect that it would be this steep and this high at the beginning!
Welcome to the wonderful world of electric power!   LL~

Dennis

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #159 on: July 25, 2021, 07:54:50 PM »
Welcome to the wonderful world of electric power!   LL~

Dennis

 ;D

I was telling someone that those scoops look they're on the "C" model of some WW2 fighter.  The "A" model had overheating problems so they stuck the scoops on so they could stay in the fight.  Then by the time they get to the "E" model they've revamped something else, and either fixed the underlying problem or built those scoops into the "real" cooling system.

The battery and ESC is as cool as I could ever want -- and if you look at the original scoop, you'll see that horizontal divider -- the top goes to the motor, the bottom to the ESC & batteries.  So you can see that maybe a revamped cowl would have a different dividing line, and maybe more area.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Ken Culbertson

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Re: Electrocuting the Atlantis
« Reply #160 on: July 25, 2021, 08:45:21 PM »
I did expect that I'd have a learning curve switching to electric.  I did not expect that it would be this steep and this high at the beginning!
True but the view from the top is stunning.

Ken

PS:

This is a response I got from Igor a few years ago when I was having similar problems.  Read the thread it makes an important point that we are cooling the wrong part of the motor.

https://stunthanger.com/smf/gettin-all-amp'ed-up!/cooling-fan-using-rearthrough-the-bulkhead-rear-mount/msg557355/#msg557355
« Last Edit: July 25, 2021, 09:07:35 PM by Ken Culbertson »
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Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #161 on: August 08, 2021, 05:48:42 PM »
With the scoops, and more careful measurement, I'm seeing about 60 degrees C immediately after a flight.

But where the Cobra motor was hot-hot and got hotter with time after a flight, indicating that I wasn't measuring the hottest part of the motor, the Badass motor is at 60C and falling right after a flight.

Moreover, the setting I started out with was giving me lap times a bit less than five seconds.  With lap times between 5.2 and 5.5 seconds (I'm just measuring with my wristwatch, so it's not accurate) I'm seeing about 5 degrees less motor temperature, and it looks like I'm using about 2100-2200mAh.

So, I'm happy.  I just ordered a bunch more of the 3000mAh batteries; when they show up I can actually do flying sessions, and maybe start trimming this thing.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline PJ Rowland

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Re: Electrocuting the Atlantis
« Reply #162 on: August 10, 2021, 11:23:28 PM »
Quite a Saga Tim.
 That poor atlantis, Paul tortured it now your doing the same. :)


Cooling is essential.

As soon as I land ,im.at 47C. I personally dont refly until its cooled to a min of 35C which takes about 7 minutes.

Cooling around the can itself is important, then have plenty of exit cooling.
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Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #163 on: August 11, 2021, 03:40:23 PM »
I'm thinking of adding more scoops, or scooping out the insides of the scoops that I installed.

I think putting the metal scoops on actually reduced airflow to the motor :o -- that's aerodynamics for you.

I think I'll be flying this with rests between flights, unless I absolutely have to do back-to-back for a contest.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #164 on: August 21, 2021, 09:01:38 PM »
Revised power wiring to the timer.  I'd been having some strange behavior where the motor would run rough in inverted flight.  The last flight, the airplane cut out early.  I landed, and when I was almost to the plane it started up again (!).

I'm 90% sure that this was due to a power wire to the regulator breaking off inside the insulation -- that would provide a condition where the power was cutting in and out, especially in a manner dependent on the airplane attitude.  The motor rough running could easily be the wires repeatedly making and breaking contact.

So I've re-done all the pertinent connections, with extra wire length so that the wires won't be pulled, and better strain relief.

So -- fingers crossed, I'm going to go back to practicing on this thing.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Paul Walker

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Re: Electrocuting the Atlantis
« Reply #165 on: October 09, 2021, 01:17:55 PM »
Revised power wiring to the timer.  I'd been having some strange behavior where the motor would run rough in inverted flight.  The last flight, the airplane cut out early.  I landed, and when I was almost to the plane it started up again (!).

I'm 90% sure that this was due to a power wire to the regulator breaking off inside the insulation -- that would provide a condition where the power was cutting in and out, especially in a manner dependent on the airplane attitude.  The motor rough running could easily be the wires repeatedly making and breaking contact.

So I've re-done all the pertinent connections, with extra wire length so that the wires won't be pulled, and better strain relief.

So -- fingers crossed, I'm going to go back to practicing on this thing.rye

Must have worked. I saw you flew at the FallFollies recently. Did it perform as expected?

Offline Tim Wescott

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Re: Electrocuting the Atlantis
« Reply #166 on: October 09, 2021, 02:59:16 PM »
Must have worked. I saw you flew at the FallFollies recently. Did it perform as expected?

Well, no -- it was better.  I'm still delighted every time I fly it at how much I don't have to worry about the engine run.

You should have put an electric motor in it in '88 -- what were you thinking?
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.


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