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Old Oct 13, 2009, 11:27 AM
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Joined Jan 2005
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Help!
Carl Goldberg SUKHOI SU-26

I have decided to convert my Sukhoi to electric, but could sure use some help.
It had a YS 120 4 stroke that was in it an it was able to hang the prop at about 3/4 throttle. Would like to have the same performance or a little better with Electric set-up.
The plane weighs, W/O motor 8 1/4 lbs.
I know there is a formula that can help me determine motor, esc, prop, & lipo pack size.
Do you think a 6 cell lipo pack set-up with the right motor & esc will be enough? Hobby city sells 6s packs fairly reasonable.
Please forgive me for something that might allready have been answered in these forums, but just looking for some advice on this conversion.
Of course I would like to keep the expense as low as I can.
I realize there is alot to consider here, Like Getting the cg foward enough, motor mount that will extend enough to fit the cowl etc. You guys are the experts. This rookie just needs some help.
Any suggestions, I thank you for in advance.
Chris
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Old Oct 13, 2009, 12:18 PM
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appleflyer's Avatar
longmont, CO
Joined May 2006
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check out motocalc, you can get a free 30 day demo that will help you figure out with setup will work well. you will probably need around 150 watts per pound and you can figure that out by multiplying the voltage times the current. if i could have the all up weight with the engine and everything that would help a lot figuring out with setup you need
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Old Oct 13, 2009, 02:04 PM
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Letchworth, Great Britain (UK)
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I think there's a thread on it somewhere here. I'm planning to convert mine next spring, and I'm looking at an AXI5330/F3A with 10S or 12S A123s - I already use 5S and 6S in other models, so will series my existing packs.
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Old Oct 15, 2009, 09:00 AM
Xtreme Nut
Kuala Lumpur, Malaysia
Joined Oct 2005
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She will want a 10S set up. Any motor equivalent to the AXI5330 will be nice. Get one of perhaps 250KV thereabouts then prop down to a 20x10 or 18x12 even. Also Rhino 20C 5S 4,900s are very very cheap!
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Old Oct 21, 2009, 12:01 PM
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Quote:
Originally Posted by tIANcI
She will want a 10S set up. Any motor equivalent to the AXI5330 will be nice. Get one of perhaps 250KV thereabouts then prop down to a 20x10 or 18x12 even. Also Rhino 20C 5S 4,900s are very very cheap!
With this setup, your looking at 74 ounces of weight with motor, esc and batteries. You might have lots of power but your rtf weight will be around 13lbs. Maybe a bit less if you got rid of your receiver battery, but personally, I wouldn't. That will be about 2 pounds heavier than your glow setup with the YS and fuel. What is your reason for wanting to go electric? Not an improvment IMO.

If cost of glow fuel is your issue or you don't like to clean oil off your plane, then go with a gas setup. You can put a DL30 in that plane and your motor, muffler, ignition, battery and fuel will be about 50oz. A tiny bit heavier than glow, but you'll get way more power.
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Old Oct 21, 2009, 03:51 PM
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Letchworth, Great Britain (UK)
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I'm looking at it from the convenience point of view. As for weight, my OS120AX that it was flying on is listed at 650 grammes, and the possible AXI 5330 replacement is 652 grammes.

Remove the fuel tank, fuel, and throttle servo and you have about 20oz (sorry about the mixed units) for an ESC and battery.

I reckon it should come out even on take-off weight -- all my (smaller) conversions so far have done, using AXI motors and A123 batteries -- and just as good or better on performance. The only way electric will be worse than glow is on flight duration, but 8 minutes is enough for me these days.
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Old Oct 22, 2009, 11:39 AM
100% electric since 1990
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United States, MA, Ware
Joined Jul 2001
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It would fly fine with 6s or 8s setups, 10s would be heavy. Check out the threads in "giant scale" and "3d" section for the following planes: 3d hobby shop 70" slick, and extreme flight rc 78" extra. These are planes in the 9-12 lb range that fly well with 6s to 8s systems.

I fly a glo-converted 1/4" staudacher with 8s lithium and a geared astro brushless 60- 2300 watts with 8s rhino packs and 75 amps, 20-12 prop. WOrks awesome in this 11.5 lb former gasser. More cells would just be more weight.
TYler
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Old Oct 26, 2009, 10:36 AM
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Have you thought about how you will access the batteries without having to take the wing or cowl off? Your batteries will probably have to go pretty far forward so you might find a problem with that.
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Old Oct 26, 2009, 04:09 PM
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Letchworth, Great Britain (UK)
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Quote:
Originally Posted by A_Pilot
Have you thought about how you will access the batteries without having to take the wing or cowl off? Your batteries will probably have to go pretty far forward so you might find a problem with that.
For me it's only a distant dream at the moment -- the model is sitting engine-less in the shed, and I'm waiting for our local hobby store to have their next special sale for local model clubs so I can order a motor and ESC cheap -- so nothing will happen until next spring, and then I'll start sorting out the detail problems and look at other threads about converting this model

I'm aware that battery is going to be a challenge because of the cowl design, but I envisage having to make an access hatch in the cowl because taking it off is not a simple matter.
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Old Oct 25, 2010, 05:38 AM
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Letchworth, Great Britain (UK)
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My local hobby shop is having a club night shortly, with good discounts, so I'm about to resurrect my Sukhoi conversion project for this winter. I'm still aiming for the AXI 5330 motor, and am leaning towards the 5330/18 at the moment because of its slight amps advantage over the 5330/F3A.

Any ideas (facts?) about why AXI produce two such similar motors, please? The difference in kv (235, 259) doesn't seem to be enough to make it worth having the two different versions.
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Old Nov 07, 2010, 07:00 AM
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long island ny
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i,m just thinking of converting one i,ve had in the rafters for 15yrs.thinking of axi 5320-18 and a 6 cell lipo. prop will be a 20x8. the only problem i see is designing a darn hatch to access the battery. btw, this is the orignal with the gear in the wing.
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Old Nov 07, 2010, 03:18 PM
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Letchworth, Great Britain (UK)
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bobt2, since I last posted in this thread I've actually taken the plunge and bought a Hyperion ZS-4045/12 motor and Atlas 90 ESC for my model. They're about 30%, or more, cheaper than the corresponding AXIs, Scorpions, or E-Flites here in the UK, and they have a good reputation. My initial thoughts for power were 10S A123 (because I've got several 5S packs), but I'll probably end up with 10S LiPo about 4000mAh to get extra flight duration and to keep the amps down to 60 or so, for about 2,000 watts for scale flying.

I've got other projects on the bench at the moment, so the motor won't be going in until later this winter. I envisage cutting a large access hatch in the top of the engine cowl, and I might replace the cowl with a fibreglass one to make it a bit stiffer.

My Sukhoi also has the gear in the wing -- sounds like the same vintage as yours.
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Old Nov 08, 2010, 06:41 AM
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long island ny
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interesting. i almost have to stay 6 cell, because i want to use the same battery as my trex550 heli. i also stole the motor idea from the extream flight 70" extra. almost the same specs as the sukhoi.
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Old Nov 08, 2010, 01:53 PM
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Letchworth, Great Britain (UK)
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I figured I want 2000 watts -- that's about 150 watts per pound for a 12.5lb model. I've got a T-Rex 500, so my first thought was 6S LiPo too, but that would need about 90 amps, which is way over the AXI 5330's capability. Also, as a matter of principle, I'd rather use more volts and keep the amps down to get the watts I need.

Then I saw the Hyperion ZS-4045/12 at 2/3 the price of the AXI and others. It'll handle 12S LiPo and 85 amps continuous.
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Old Nov 08, 2010, 07:14 PM
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long island ny
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nice motor, but again, i will be using 6 cell/ 5000 packs in the 550. that means in the long run the axi is more cost effective to me.
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