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Old Apr 24, 2014, 08:58 AM
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United States, MI, Grand Ledge
Joined Jan 2013
146 Posts
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Pica Duelist Conversion

As the title implies, I am seriously considering converting a Duelist to electric. This will be my first serious conversion, and am curious about each component in the powertrain, motor, esc, and battery. For those not familiar with the Duelist, it was designed to be flown with a pair of 2 stroke 40's.Its a sleek plane, well adapted to pattern style aerobatics. As you may image, all sorts of power has been stuffed into the nacelles. Speeds of well over 100 mph have been comfortably achieved with this airframe.

In my case I am leaning toward a more "stock" power range, somewhere in the 3/4 hp range, swinging a 11-6 to a 10-8 prop. Rather than speed I would like to have a nice vertical, but way less than a 1:1 thrust to weight ratio. I want the plane to eventually stall during a steep climb. No 3D flying for this plane.

Having determined motor, how about esc ? Is it desirable to over rate the esc for cooling? I understand the esc in the airstream, but what happens to linearity of rpm range with a too big an esc? How about battery time?

Speaking of batteries, do I use 1 or 2? If two, I see need to sync for powerout on one side or the other. I really am not a fan of yaw induced crashes. How do I determine the discharge rating for the battery? I'm sure that it all hinges around the max current discharge rate, possibly the capacity as well. Maybe a rule of thumb here?

Any advice will be seriously considered. May pose a "what if" type of response to help me understand better. Realize from the get go that I DO ask questions, but NOT to be argumentative. I see electrics as being my power choice for the future, therefore I need to learn as much as possible.
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Last edited by sdad; Apr 24, 2014 at 09:09 AM.
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Old Apr 24, 2014, 09:20 AM
Registered User
United States, MI, Grand Ledge
Joined Jan 2013
146 Posts
Just looked up specs on an OS40FSR, an engine that might have powered the Duealist. I found a HP rating of 1.2 HP, though I didn't see a rpm associated with the hp. Weight of the plane is in the 10# range. Want retracts, so 9" prop will be it (ground clearance issues), maybe a 3 blade?

At the low end of the design power, an OS25FSR produced about .8HP.
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Last edited by sdad; Apr 24, 2014 at 09:48 AM.
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Old Apr 24, 2014, 08:57 PM
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United States, GA, Valdosta
Joined Sep 2007
128 Posts
Will be watching this been thinking a long this line to. Problem is prop clearance when you have retracts I was thing about two inrunners with batteries were gas tanks were like the Deuce wild by eflite I can only fit a 11 in. Prop if I remember.
It be a different and a good flying plane I have to get mine out.
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Old May 02, 2014, 06:46 PM
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Lake Orion, MI
Joined Jul 2004
91 Posts
See this thread for my experience:

http://www.rcgroups.com/forums/showt...t#post12619505

Robyn
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Old May 02, 2014, 07:29 PM
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United States, MI, Grand Ledge
Joined Jan 2013
146 Posts
I like your thread. You say that about 400 watts per motor, and spun an 11x8 3 blade. Recall rpm wot static by any chance? Just curious.

Back to the ic power, the 40fsr produces about 900w each, while the 25fsr produces about 600w each. Again, I am not sure what the other parameters were to derive these power values. Your 800w total, has me wondering how I relate these ic engines to the electrics. Perhaps there is some verbage out there that will allow me to not scratch all my hair away?
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Old May 02, 2014, 07:58 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,758 Posts
Umm- I did this airplane a few years back too. Here's my thread. I came up with a setup that I think is a bit closer to what you're looking for. These days, I've got some new batteries to try- 5s 3300 which are a lot lighter and should actually hold higher voltage.

If you've got more questions- feel free to fire away.

http://www.rcgroups.com/forums/showt...ist+fli&page=2

Sam
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Old May 02, 2014, 08:47 PM
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United States, MI, Grand Ledge
Joined Jan 2013
146 Posts
Megowcoupe.... Thanks for your post. You're right, your motor selection is a bit more in line with what I would expect. I did run across a "sticky" that guides an idiot such as myself in selecting a motor. Be interesting to see what the application says to use. Be a couple of days before I do that, however.

So what's with this brake thing? I remember seeing a you-tube video of a plane that hit prop reverse a bit early. That was ugly. Hopefully the brake thing isn't the same, maybe more it emulates the ic engine braking effect? That I'd like. Have you tried mixing brake with throttle position? (assuming a seperate input for brake)
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Old May 02, 2014, 08:56 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,758 Posts
I must admit- I haven't bothered with the brake thing at all- I think it's an issue of pilot error.

Please note- some folks go cheap with motors and ESCs- I don't. In a twin, this is really critical because if the motors run up unevenly, you can get a nasty swing on takeoff. I've had lousy luck with Chinese stuff- especially motors being closely matched- and I've never bothered with HK ESCs.

You may want to try a single rather than a twin for your first conversion- it's a bit less nerve wracking and there are some things like motors coming on if you turn off a Tx that can be unsettling. You really have to treat the motors as live the minute the batteries are plugged in.

HTH

Sam
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Old Oct 28, 2014, 08:55 PM
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United States, FL, Port St Lucie
Joined May 2012
7 Posts
I built the duelist last year using 2xpower up sport 46 outrunners, 80 amp esc,and 2 x 4s 3300 batteries mounted under the canopy, using 13 x 6.5 counter rotating props. I modified the fuse to make the canopy lift off.

She flies well, 45 degree climb is no problem. Flies well at half throttle, nice aircraft. I glassed and painted entire ship, total weight ready to fly 9.5 lbs.

Shows 650w per motor, 9400 rpm. 7+ minutes flight time, everything stays cool.
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Old Oct 29, 2014, 07:49 AM
I just want to go fly!
walter3rd's Avatar
United States, MD, Towson
Joined Aug 2012
2,496 Posts
im going to run power 32 in mine with 3 blade and 4s batts to start. 75 amp esc cc. having alot of fun so far. first conversion and 2nd, kit build. love her. p.s. the fuse is now covered in the brushed aluminum ultracoat in sections to look like aluminum panels! looks fantastic but my camera is acting up.
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