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Author Topic: Glow to Electric Conversion  (Read 1374 times)

Offline Don Jenkins

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Glow to Electric Conversion
« on: November 10, 2021, 07:00:46 AM »
I have decided to convert my Dreadnought to electric, I'm just done with IC engines.  I'm thinking the best way to mount the motor is a rear mount configuration (my other 3 electric planes are front mount) so I have no experience with this set up.  Any insight, especially photos would be greatly appreciated, if there is already a thread on this topic, I apologize for any duplication, but reference to that thread would also be appreciated.

Don

Offline Dennis Toth

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Re: Glow to Electric Conversion
« Reply #1 on: November 10, 2021, 09:12:45 AM »
Converting is a matter of getting the balance correct as you install components. One thing you can do is remove the maple mounts and install a good firewall 3/16" to mount the motor off of (use gussets to reinforce and small wood screws through the fuse plywood sides). I like front mounts but the rear mount might be easier for the conversion. I would leave a little extra space (like 1/16") between the spinner and cowl ring to allow some movement.

Best,   DennisT

Offline Dennis Toth

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Re: Glow to Electric Conversion
« Reply #2 on: November 10, 2021, 09:35:31 AM »
A flying buddy of mine had this happen a couple times. I added the wood screws (4 of them) through the fuse plywood into the motor/firewall mount and never had problems but I would make sure the prop is balanced and it runs true when spinning.

Best,   DennisT

Offline Shorts,David

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Re: Glow to Electric Conversion
« Reply #3 on: November 10, 2021, 10:13:46 AM »
One advantage of the rear mount electric is it is simple to convert to IC using an rc engine mount, as I'm doing with my oriental.

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #4 on: November 10, 2021, 12:41:41 PM »
I am a fan of the forward mount but it is so integral to the design that a rear mount is probably easier for a conversion.  I personally like the through the firewall mount where the motor slides through the firewall from the rear and mounts to the back side with blind nuts up front.  I have a pix somewhere.  I will post it if I can find it. Cooling will be your biggest problem.  Most IC noses are only concerned with cooling a cylinder head.  You now have a motor, battery, ESC, timer and the trained mouse that keeps everything running.  I found that mounting the ESC and timer somewhere in the old pipe tunnel helped use existing airflow paths.  The cowling has to come off for the battery so why not mount stuff on 't's floor. Another thing I did on one was to keep the nose uncovered until I had flown it to see if the motor offset was right. With a rear mount, the spinner moves a bunch more than with a nose mount.  That way you can blend it in no matter what.  Larger that IC spinner gap. Much of the motor's cooling is through that gap.  If you can get the motor mounts out, do it.  You don't have the vibration to deal with.  OR, better yet, chop the whole thing off and build a proper E-nose. because, if you have 3 electrics already you already know that the motor leads are too short, the timer needs to be on the other side, the battery is too long and the ESC is 1/8" wider than the space it has to go in. mw~ 

Ken

Pix - this is the BACK of the firewall.  Motor slips through the hole and bolts in from the rear.  Don't forget side screws and triangular braces on all 4 corners.
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Offline Dennis Toth

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Re: Glow to Electric Conversion
« Reply #5 on: November 10, 2021, 01:43:29 PM »
If you do the firewall mount to the fuse sides make sure that after you epoxy in the FW drill a small pilot hole for the screws then one at a time using thin CA soak the hole in the firewall to harden the FW and quickly insert and sock down the wood screw before the CA sets. Move to the next hole - repeat, etc.

Best,    DennisT

Online Ken Bird

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Re: Glow to Electric Conversion
« Reply #6 on: November 10, 2021, 04:56:45 PM »
Don,

I converted a Geo XL from a piped PA 61 to Electric with a rear mount for my first go at electric power. I did not build the original model so it was relatively easy for me to take the appropriate steps without any of the emotional challenges that might come from cutting into a functioning model. I had a few other items that needed to be addressed with the airplane so I was able to accomplish that at the same time.

I'm glad I did what I did and I have not looked back with respect to electric power. This particular plane is retired now but gave me an excellent platform to learn the steps of the power system. 

I put together a small Google photo album with the pictures of the modifications that are relatively self explanatory. You can see them here: https://photos.app.goo.gl/5T2CJBcaUgKbKao9A

Hope this helps you.

Ken 

Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #7 on: November 11, 2021, 07:18:39 AM »
Thanks for the replies.  Ken, the pictorial is very good, your craftsmanship is impressive and gives me some ideas on how to proceed.  It appears you mounted the ESC/Timer above the battery, was there enough air flow up there to keep things cool, or did I miss something in the photos?

Don

Online Ken Bird

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Re: Glow to Electric Conversion
« Reply #8 on: November 11, 2021, 08:52:38 AM »
Don,

I did suspend the ESC above the battery and I opened up the front of the fuselage at the spinner area and used a smaller spinner. That provided an annular inlet primarily for the motor but does provide a little for the ESC as well. In addition, I felt that there was enough space and inlet holes in the cowling at the front of the fuselage to provide adequate circulation. I was prepared to add another inlet at the top of the  fuselage if need be as well as internal cooling baffles to redirect the flow but as it turned out, it was not required.  The Igor timer was mounted along the pipe tunnel floor.

One thing I should mention is that I fly in a more northerly latitude and the temperature at the flying field doesn’t typically exceed 85 degrees F on the hottest days, which may have bought me some grace in the cooling department.

Ken

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #9 on: November 11, 2021, 09:43:09 AM »
I found the last surviving photo of my through the firewall mount.  This plane had a pipe tunnel and I mounted the esc behind the battery in the tunnel.  I vented through huge slots in the aft fuselage bottom and by reshaping the pipe exit ala Gieseke. The timer and all of the wiring for the switches, plugs, etc was in the cowl.   This way when I opened it up to change the battery I had access to everything.
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Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #10 on: November 13, 2021, 07:05:53 AM »
Thanks again both Kens.  I think I got it figured out enough to grind out the nose of my Dreadnought, there's no turning back now!  The next time it flies will be on a battery!

Don

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #11 on: November 16, 2021, 03:57:27 PM »
I found the last surviving photo of my through the firewall mount.  This plane had a pipe tunnel and I mounted the esc behind the battery in the tunnel.  I vented through huge slots in the aft fuselage bottom and by reshaping the pipe exit ala Gieseke. The timer and all of the wiring for the switches, plugs, etc was in the cowl.   This way when I opened it up to change the battery I had access to everything.
If it is not too late, I found a better one here.  Big bottom hatch and the mount gives you a real cavern for all that wire stuff.

https://stunthanger.com/smf/index.php?action=dlattach;topic=55495.0;attach=307172;image

Ken
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Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #12 on: November 17, 2021, 06:00:35 AM »
Well, four days of work, (mostly spent staring and trying to think) and just under $200 in parts, the Dreadnought has been converted to e-power.  I programmed the ESC and Timer, now all I'm waiting for is battery hold down straps and a 2 inch CF uncut spinner, both should get delivered in a few days.  Thanks for the replies and pics from all that contributed to my quest!

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #13 on: November 17, 2021, 06:55:12 AM »
Well, four days of work, (mostly spent staring and trying to think)!
No one in my family has ever understood this part!

Really nice Job.

Just curious why you elected to go with a front mount instead of through the firewall.  Glad to see you make use of the cowl.  It has to come off to change the battery so why not make it useful!

Ken
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Offline Dennis Toth

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Re: Glow to Electric Conversion
« Reply #14 on: November 17, 2021, 09:40:57 AM »
Don,
Very nice job. Since you are almost finished remember that Thunder Power's Black Friday sale is just around the corner - basically it is two for one. They should be announcing it soon, Frank Imbriaco usually get the word out in this Forum.

Best,   DennisT

Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #15 on: November 18, 2021, 06:21:54 AM »
Quote from: Ken Culbertson link=topic=60530.msg625309#msg625309 date=1637157312

Just curious why you elected to go with a front mount instead of through the firewall. 

[/quote

I intended to go through the firewall, which looks to be more robust since the firewall is closer to the nose, but I couldn't make it happen.  I started out with a 3520 Cobra motor, but it was too large to fit in the nose with little wood left to remove to get proper clearance.  So I opted to go with a 2826 760KV Cobra which fit in the nose, but the mounting bracket it came with is really too small to use. During my mock up using a piece of 1/8 inch balsa firewall, the size of the hole to fit the motor through the firewall almost went through he mounting holes.  I then used the larger mounting bracket from the 3520 motor but it too came really close to the mounting holes, and I didn't want to run the risk of weakening the mounting set up.  It probably would have been OK, but I have little experience with e-power, so I'm still unsure what I can get away with regarding how beefy motor mounting must be.  I probably won't have to do anymore conversions, I'm building everything e-powered from now on.  All my IC planes are smaller .46 powered and don't fly that well, so they will just be wall hangers!

Don
« Last Edit: November 18, 2021, 06:53:03 AM by Don Jenkins »

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #16 on: November 18, 2021, 07:31:01 AM »
[quote author=Ken Culbertson link=topic=60530.msg625309#msg625309 date=1637157312

Just curious why you elected to go with a front mount instead of through the firewall. 



I intended to go through the firewall, which looks to be more robust since the firewall is closer to the nose, but I couldn't make it happen.  I started out with a 3520 Cobra motor, but it was too large to fit in the nose with little wood left to remove to get proper clearance.  So I opted to go with a 2826 760KV Cobra which fit in the nose, but the mounting bracket it came with is really too small to use. During my mock up using a piece of 1/8 inch balsa firewall, the size of the hole to fit the motor through the firewall almost went through he mounting holes.  I then used the larger mounting bracket from the 3520 motor but it too came really close to the mounting holes, and I didn't want to run the risk of weakening the mounting set up.  It probably would have been OK, but I have little experience with e-power, so I'm still unsure what I can get away with regarding how beefy motor mounting must be.  I probably won't have to do anymore conversions, I'm building everything e-powered from now on.  All my IC planes are smaller .46 powered and don't fly that well, so they will just be wall hangers!

Don
When I first started doing Electric I assumed that airflow over the motor cooled it.  I was wrong. It is airflow through the motor so a close fit on the mounts is not critical.  I cut the hole to just barely clear the motor.  Install the blind nuts then clear away as much wood as I can on the sides and top.  There is a lot of torque when the motor starts up which can be regulated in some ESC's.  That is why I brace the mount with triangular strips.  The 2826 is a good motor, only problem is that it is regulated to 5s.  Actually a 2820 on 4s is a .46 equivalent.  You will be fine.

Ken
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Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #17 on: November 22, 2021, 06:47:08 AM »
I got in two 2 minute trim flights yesterday with the newly "electric converted" Dreadnought, added a bit of nose weight, then got in a full pattern.  Very happy with my decision to go electric, flies great, good line tension every where and turns on a dime!  Now for some practice and fine tuning!

Don

Offline Mark wood

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Re: Glow to Electric Conversion
« Reply #18 on: November 22, 2021, 07:24:51 AM »
Don,
Very nice job. Since you are almost finished remember that Thunder Power's Black Friday sale is just around the corner - basically it is two for one. They should be announcing it soon, Frank Imbriaco usually get the word out in this Forum.

Best,   DennisT

The Hobby Star 5S 3000 MAH in Don's photo is actually a super good battery and lighter than the TP 3300 which is twice the price. On sale the TP would be basically the same price as the HS battery. The HS's go on sale for $39 winning the price battle especially since the TP doesn't come with a connector. I have 7 of the same HS 5S 3000MAH battery and 5 are in the 35 charge cycle zone and still going strong. In Don's position, which I am, I would just add to my HS inventory when RC juice puts them on sale again. Reason being is that I parallel charge and that isn't something I could do with a mix of battery brands. I'm guessing through total speculation though that both the HS and TP batteries come out of the same factory and the TP 5S 2800 and the HS 5S 3000 are the same battery but I wouldn't mix them during charging.
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Offline Mark wood

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Re: Glow to Electric Conversion
« Reply #19 on: November 22, 2021, 07:35:23 AM »
Well, four days of work, (mostly spent staring and trying to think) and just under $200 in parts, the Dreadnought has been converted to e-power.  I programmed the ESC and Timer, now all I'm waiting for is battery hold down straps and a 2 inch CF uncut spinner, both should get delivered in a few days.  Thanks for the replies and pics from all that contributed to my quest!

It's hard to tell but it doesn't look like there is enough motor compartment exit. Perhaps there is a space between the mount bulkhead and the cowling which is good. The area of the outlet needs to be larger than the inlet by 1.5 times ish. There doesn't appear to be a good channel for air to get in to the ESC battery compartment either. Those will survive but the life is reduced when they get warm. As my time has progressed with build electrics I have gotten to a place where I provide two separate cooling air paths, one through the motor and one around and to the battery compartment. That's hard to do with a direct conversion though without modifications.

Overall great job. Electric is the way.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Don Jenkins

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Re: Glow to Electric Conversion
« Reply #20 on: November 23, 2021, 06:16:42 AM »
It's hard to tell but it doesn't look like there is enough motor compartment exit. Perhaps there is a space between the mount bulkhead and the cowling which is good. The area of the outlet needs to be larger than the inlet by 1.5 times ish. There doesn't appear to be a good channel for air to get in to the ESC battery compartment either. Those will survive but the life is reduced when they get warm. As my time has progressed with build electrics I have gotten to a place where I provide two separate cooling air paths, one through the motor and one around and to the battery compartment. That's hard to do with a direct conversion though without modifications.

Overall great job. Electric is the way.

Thanks Mark.  I think I have sufficient air flow to keep the ESC and Timer cool, but I am concerned about motor cooling.  I'm having a difficult time finding either uncut spinners or pusher prop spinners to improve air flow.  Gator RC has slotted spinners with slotted backplates for electrics but only for counter clockwise rotation.  I am sold on the F2B APC 12 X 6 pusher prop and will stay with it.  I was thinking about using a smaller 1.75 inch spinner and opening the nose ring, but I just don't like the look.  (The aluminum spinner and tractor prop in the pics was just for the pics.)  I'll keep trying to fix the air flow issue, but for now I got some cooler temperatures to fly in which should help!

Don

Online Ken Culbertson

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Re: Glow to Electric Conversion
« Reply #21 on: November 23, 2021, 07:05:54 AM »
I was thinking about using a smaller 1.75 inch spinner and opening the nose ring, but I just don't like the look.  (The aluminum spinner and tractor prop in the pics was just for the pics.)  I'll keep trying to fix the air flow issue, but for now I got some cooler temperatures to fly in which should help!

Don
I once tried to find a cooling fan for the motor and searched the RC sites.  What I found out was that nobody uses them anymore.  If I am wrong, I hope someone will straighten me out but there are two places a motor needs cooling.  Inside and out.  The Cobra and BadAss from what I learned draw air through the motor by design.  The can is spinning at whatever RPM you are at so there really is no "Top" or "Bottom" to the motor and airflow on either side will carry away the heat.  You just need to vent that air.  Again, I am going on what I learned on my RC site search.  The motor pulls air through in one direction and it matters whether you have a front or rear mount and the direction of rotation.  If your motor is venting forward a slotted  spinner backplate may be blocking the flow.  A wider than you would use for IC spinner gap (I use 1/16") will work.  I agree, on your plane, for a smaller spinner would need a nose job.  Baffles work wonders in directing air and purging dead spots.  One place that will help the overall flow is to put an angled baffel in the rear of the cavity.  When I converted my Nobler it had a nose very similar to yours.  I ended up putting two suction vents on the side at the very end of the cavity.  Mine already had the "over the crankcase" hole.  Both of those helped in venting after the motor quit.  This may sound dumb but you might have too much venting on the bottom.  It is hard to tell if that large bottom is intake or exit.  "Perfect" cooling is in the design and an IC design will never do the same job so all we can hope for is cool enough to not do damage. A lot of that is matching the prop and battery to the motor.  A higher "s" will run cooler.  I am as far as you can get to being expert in this area but others here are.

Good luck and again - Great Job!

Ken
PS: sorry to be so long winded.  Two other observations.  Is there any gap between the battery and the floor to carry off battery heat?  I use 1/4" tall basswood strips on the floor to give it a gap.  Second, is there a hole in the motor mount near the top?  I think you are creating a dead zone around the motor.
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Offline Mark wood

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Re: Glow to Electric Conversion
« Reply #22 on: November 23, 2021, 07:38:50 AM »
Thanks Mark.  I think I have sufficient air flow to keep the ESC and Timer cool, but I am concerned about motor cooling.  I'm having a difficult time finding either uncut spinners or pusher prop spinners to improve air flow.  Gator RC has slotted spinners with slotted backplates for electrics but only for counter clockwise rotation.  I am sold on the F2B APC 12 X 6 pusher prop and will stay with it.  I was thinking about using a smaller 1.75 inch spinner and opening the nose ring, but I just don't like the look.  (The aluminum spinner and tractor prop in the pics was just for the pics.)  I'll keep trying to fix the air flow issue, but for now I got some cooler temperatures to fly in which should help!

Don

I personally like the annular inlet for the motor cooling. I plagiarized Tom Morris's mount that Russ sells and us it in my airplanes. By itself maybe I don't care for it but when combined with some cheek cowling and stuff it works. It is the simplest way to get the air going in to the motor. A 1/16 gap between spinner and ring is enough to feed the motor with a front mount. With a conversion like you are doing, simply pushing the spinner out that 1/16 would do. That's what I did on my SV and it seems to be doing fine. Here's some photo's. I am a fan of how the horizontal engine cowling looks on airplanes and how it is adaptable to our models for cooling so it has become a bit of a trademark for me
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman


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