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Author Topic: First Electric Model?  (Read 2231 times)

Offline Neil Rogers

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First Electric Model?
« on: September 25, 2018, 03:49:37 PM »
I'm an advanced level flier who flies large Randy SV airplanes and I've decided to switch to electric power for next year.
So my question is, what would you recommend as a first electric model to build?
I would like something that's designed for electric so that I don't have to worry about structural conversions for my first airplane, but I'm open to all suggestions.

Neil Rogers

Offline MikeCoulombe

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Re: First Electric Model?
« Reply #1 on: September 25, 2018, 04:09:39 PM »
Hi Neil
I have copies of Igors GeeBee
And Bobs Crossfire plans if you want to borrow them you are welcome to it.
I'll pm you my new cell #.

« Last Edit: September 25, 2018, 04:38:00 PM by MikeCoulombe »

Offline TDM

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Re: First Electric Model?
« Reply #2 on: September 25, 2018, 08:39:49 PM »
Make another SV and modify for electric.
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Joe Yau

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Re: First Electric Model?
« Reply #3 on: September 25, 2018, 08:43:30 PM »
I'm an advanced level flier who flies large Randy SV airplanes and I've decided to switch to electric power for next year.
So my question is, what would you recommend as a first electric model to build?
I would like something that's designed for electric so that I don't have to worry about structural conversions for my first airplane, but I'm open to all suggestions.

Neil Rogers

Hi Neil,  Are you thinking of building from a kit or an ARF/ARC kit?   Brodak has an Electric SV-11 ARF version available.   Otherwise from the top of my head.. the Thunder Gazer from the RSM kit has optional for Electric power.  or maybe Paul Walker's  Predator (plans only)   not sure if the Blue Max has the E option  or not.. but it is really not too hard to convert from IC to Electrics.

Offline Neil Rogers

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Re: First Electric Model?
« Reply #4 on: September 25, 2018, 10:25:40 PM »
Joe, I initially thought of an SV11 ARF, but I want an airplane that will get pretty points.  A kit would be nice, but I have no issues building from plans.

I would like something designed for electric so I don't have to figure out how to do the conversion the first time out.  I'm on my own here in Edmonton, although Chris has been providing some good information by phone and email.

Neil rogers

Offline Dennis Adamisin

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Re: First Electric Model?
« Reply #5 on: September 26, 2018, 07:37:31 AM »
I'm an advanced level flier who flies large Randy SV airplanes and I've decided to switch to electric power for next year.
So my question is, what would you recommend as a first electric model to build?
I would like something that's designed for electric so that I don't have to worry about structural conversions for my first airplane, but I'm open to all suggestions.

Neil Rogers

Hi Neil

Brodak offers electric conversion kits that make it pretty easy to convert almost any IC design to electric.  Some are "Universal" some re designed for specific designs.  For SV-class designs I would recommend the Universal "B" kit (#BH-1944, for rear mounted motors) or the Legacy Kit (#BH-1926, for front or rear mounted motors).  To give you an idea of what is involved I have attached a copy of the instruction manual that comes with the Legacy Conversion Kit.

As for what airplane to build - any/all are in play!
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline Joe Yau

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Re: First Electric Model?
« Reply #6 on: September 26, 2018, 10:06:58 AM »
Joe, I initially thought of an SV11 ARF, but I want an airplane that will get pretty points.  A kit would be nice, but I have no issues building from plans.
Neil rogers

Some insight.. The Legacy I flew at the WCSC was my very first Electric. It was converted from IC using Bob Hunt hardnose mount.  (for front mount) started out with the E-flite 32 motor then AXI (almost an ounce lighter).   then shortly after I converted the Saturn and also the Pathfinder.  On the Saturn, I removed the maple mount to where the batt tray will sit and added 1/32 doubler all the way to the nose ring  which the mount is secured on. I did rear mount on that one. and the Pathfinder, I used an adapter to beam mount from Arkady G,  just some slight mod on the maple mount to clear the bell, and line up the spinner to the nose ring.  all worked very well.  But it all could be a fresh scratch built with the same mount integration to get those pretty points.  :)

Quote
I would like something designed for electric so I don't have to figure out how to do the conversion the first time out.

 Igor’s Max Bee is also a good one. unfortunately the kit is no longer available. But I believe there are rib set available.  and Chris’s Hell Cat is designed strictly for Electric as well. I think his Defiant would be a very good one to get into for Electrics.
« Last Edit: September 26, 2018, 03:11:30 PM by Joe Yau »

Offline TDM

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Re: First Electric Model?
« Reply #7 on: September 26, 2018, 10:12:26 AM »
Neil you can make anything IC in to Electric. Drop the engine crutch use minimum doublers 1/64 ply is plenty add a nose ring to attach the motor to it. You do not need a nose cowl anymore but you need a way to replace the battery, also think about how to facilitate air flow over the electric components and that is it. For wing modifications I would thin out the airfoil to 15-16% and tip airfoil to 14%. Less drag means smaller battery that will save the weight and compensates for the little bit less lift. Smaller battery is good for the pocket book. So pick a plan you like and run with it.
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Neil Rogers

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Re: First Electric Model?
« Reply #8 on: September 26, 2018, 12:00:18 PM »
Hi Dennis,

That was very useful information.  Thanks!

Neil Rogers

Online Howard Rush

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Re: First Electric Model?
« Reply #9 on: September 26, 2018, 12:07:22 PM »
For wing modifications I would thin out the airfoil to 15-16% and tip airfoil to 14%.

I wouldn't.
The Jive Combat Team
Making combat and stunt great again

Offline Crist Rigotti

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Re: First Electric Model?
« Reply #10 on: September 26, 2018, 12:11:46 PM »
Crist
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Waxahachie, TX
Electric - The Future of Old Time Stunt

Online Howard Rush

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Re: First Electric Model?
« Reply #11 on: September 26, 2018, 12:20:46 PM »
Chris is a good source.  He has built several good electric airplanes. 

I have a couple observations.  First, if you do the modification from an existing acoustic-airplane design yourself, when you calculate CG, assume that it will be an inch or so forward of the original CG. Second, you are no longer constrained to have engine mounts glued to the fuselage side, so you can make the fuselage wider.  This enables it to be lighter for a given strength or rigidity and allows more room for the electrickery and cooling thereof. 
The Jive Combat Team
Making combat and stunt great again

Offline Crist Rigotti

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Re: First Electric Model?
« Reply #12 on: September 26, 2018, 03:14:14 PM »
...snip...

I have a couple observations.  First, if you do the modification from an existing acoustic-airplane design yourself, when you calculate CG, assume that it will be an inch or so forward of the original CG. Second, you are no longer constrained to have engine mounts glued to the fuselage side, so you can make the fuselage wider.  This enables it to be lighter for a given strength or rigidity and allows more room for the electrickery and cooling thereof.

Howard is exactly right!
Crist
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Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline TDM

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Re: First Electric Model?
« Reply #13 on: September 27, 2018, 06:10:07 AM »
Howard Crist why is that? You should back up your claim. We need a reason why. And "because you have always done it like that" is not a reason. Sorry I always question why, and that is because I need to understand the reasoning behind it?
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Crist Rigotti

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Re: First Electric Model?
« Reply #14 on: September 27, 2018, 07:20:06 AM »
I built a model using the "standard" width of a IC engine and the electric system ran rather warm.  The next model was IIRC 3/8 or 1/2 wider, the same electric system ran much cooler.

I also had a model with a "reduced" thickness airfoil and one with a "standard" thickness airfoil.  IMHO the thicker airfoil had a better quality flight to it.
Crist
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Electric - The Future of Old Time Stunt

Online Howard Rush

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Re: First Electric Model?
« Reply #15 on: September 27, 2018, 12:24:19 PM »
Howard Crist why is that? You should back up your claim. We need a reason why. And "because you have always done it like that" is not a reason. Sorry I always question why, and that is because I need to understand the reasoning behind it?

You want me to do the work, but would you read it?  See again https://stunthanger.com/smf/gettin-all-amp'ed-up!/thinking-elelctric/msg505607/#msg505607 .  Section drag doesn't vary much with airfoil thickness, although people intuit that it's proportional.  If you thin the section from what's optimal, you'll reduce max lift coefficient--hence weight-carrying capacity-- faster than you'll reduce battery weight.   You are better off keeping the optimal airfoils folks have evolved over the years.  If you want less drag, make the airplane smaller. 

I had a discussion with a famous stunt flier this past weekend that got me thinking.  To wit, I think that stunt airfoil selection involves a trade between max lift coefficient and flap hinge moment coefficient.  I don't think drag is involved.

I fly an Impact, an old pipe-engine design, electrified.  It works a treat.  I am contemplating changing the airfoil to something plumper if analysis indicates it would be better.
The Jive Combat Team
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Offline GerryG

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Re: First Electric Model?
« Reply #16 on: September 27, 2018, 03:19:12 PM »
Here is a real live test of what you say Howard. The past winter I built two Cardinals. The first was a standard Brodak profile Cardinal powered by an Arrowind 2826. The second was a Dixon full fuse Cardinal powered by an E-Flite 25. It turns out that the wings of the two are not the same as they first appear. The Dixon Cardinal has a foam wing that is thicker and with a blunter leading edge than the profile Cardinal. The full fuse plane weighs only about an ounce more than the profile. The profile is turning out to be a real chore to trim. I shocked my flying buddy by doing close to a full pattern on the first flight with the Dixon Cardinal. The Dixon Card with the thicker airfoil is a lot more pleasant to fly. A couple of construction notes. The profile fuse was hollowed and sheeted with 1/64 plywood and is quite stiff. Both planes have their flaps pruned by 3/8 inches.


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