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Aug 20, 2018, 02:58 AM
Thread OP

"Extra time", with "Eflite360"/6Kw/12S set up. 'Extra size prop'

After the check of my log book, it is 10 years since my first flight with this "Extra 300" quarter scale model originally fitted with "DA 50 cc" motor, Pitt style exhaust and Emcotec electronics. At ~8.6 kilo AUW it was pretty lively model, capable of some basic 3/D aerobatics with the use of Wess 23A/8 prop. Over the years I had some great enjoyment and also few lows, with 3 engine stoppages recorded, two due for not using the header tank and ones engine quitting while running little too hot on very warm summers day, unfortunately this time resulting in some frame damage, which was easilly fixed and model returning back to action running slightly richer.

With the times and all the improvement in electrics I'm getting involved in, mainly EDF powered jets I have accumulated nice collection of high voltage and capacity lipo batteries and recently though of, why not to "elektrofly" this model. Almost identical, but only 2 meter size model with the much smaller EF50/20, electric motor running on 10S, proved to be the most reliable after hundreds of flying sessions to date, so after little search I have discovered there is a huge range of electric motors available to power this larger size of models and decided to go for it.

Selling my IC set up didn't take that long, basically giving it away at peanuts but close enough to purchase the new "Eflite 360", 6 Kilowatt electric motor, after having such a great experience with this brand in smaller 10, 32 and 46 sizes to power variety of my own design fun-fly models. With the wide range of high voltage electronic speed controllers available as part of my EDF fleet I decided to use modified "Sun Rise 180" amp one. Recommended max. peak of 150 amps for this motor at 12/S, seem the right combo but unfortunately ESC comes only wraped up in heat shrink which is a "no-no" as far as I'm concerned for HV power unit, so minor moddifiation by adding extra cooling heat sinks to Fets on each side proved to run it reliably over the years in some of my high current draw electric jets.

The ESC was placed in the position to minimize the length of the power leads just at the entrance of fuselage air tunnel. I have also added extra set of capacitors to the slightly longer than recommended battery leads which is a norm in all my high power electric set ups. Large 6.5 mm gold bullet connectors were used to hook it all up. There was a great surprise after receiving the motor, fitting perfectly to my DA 50 stand offs inside the covel of the engine box compartment. After simple power unit installation with couple of degree down thrust I have experimented with various capacity batteries to find the best placement position for correct centre of gravity. Minor changes were done with the use of balsa sheeting to create new vains to direct air flow over the motor and the speed controller for cooling. I purposely emit use of the prop spinner in this model to maximize the air intake and flow over my battery compartment inside the fuselage and also to minimize the load on ball bearings plus eliminate any possibility of motor vibration. Small 5 ch. Power Box system replaced my original Emcotec electronic set up with 5000mA, 6 volt battery supply, providing power to all high torque operating servos.

With the mid range battery capacity at 5200mA, (1750Grams) the AUW of the model came up some 750 grams more than the full internal combustion wet set up which I have expected for this electric conversion.
After my first static run with the use of light electric prop I have replaced it for more efficient one but still less loaded than recommended one to start with. The quick static pull check was just around one to one power to weight, (~9.5kg) rather impressive for e-powered model of this size on light loaded prop. Since I have build this model it was operating on 36 meg. frequency using 9Ch. SPCM receiver, but after this conversion the change was necessary to 2.4 gig. to eliminate any possibility of interference so new Spektrum 8ch. receiver with Sattelite antenna was hooked up to my Power Box and the whole system re-bind.

Few more static check runs to simulate the flight time was performed to see how it loads the motor, ESC and the two 5.2Ah batteries hooked up in series as 12S/5200/60C. There was no excessive heat recorded with all units running rather cool.
The thorough range check was performed next, with the model running at various throttle settings at some 300+ meters distance showing all positive result. The process of this conversion was lot simpler than I have actually expected and I'm most delighted creating a new model I can now enjoy flying at the sites where I did not dare to do with the very noisy internal combustion power unit.
All ready and impatient for the maiden flight is interupted as usually with the horrendous southerly cold and extreme windy conditions which is a typical scenario in most cases I complete some new project, but being a winter time in Souther Hemi the one has to put up with it.
Stay tune for the further report, JF.
Last edited by jofro; Oct 05, 2019 at 02:38 AM.
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Aug 28, 2018, 02:02 AM
Thread OP
Quick check with the clamp meter confirms very low current draw on full stick of less than 90 Amps, with 23x8 prop. Not surprise the motor/ESC and batt. stay so cool, giving me lot of room to play with more aggressive props if needed.
Aug 28, 2018, 11:49 PM
Thread OP
After the first flight today in rather nice conditions I only regret I haven't done this conversion earlier.
Aug 30, 2018, 09:17 PM
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scirocco's Avatar
Were you satisfied with the speed with the 8" pitch prop?

I'm tossing up between 149 rpm/V and 192 rpm/V for an 8kg 78" CMPRO Extra. Leaning towards the lower Kv due motor rpm on 12S and as long as I run at least 10" pitch I should achieve similar pitch speed to your setup. Power will be only about 2500W but will be plenty for what I want to do.

Appreciate any thoughts you may have as many of my setups are biased towards higher speeds.
Aug 31, 2018, 03:03 AM
Thread OP
Hi Body, with my current prop I got some 6600 RPM on full stick, if you are after speed you are naturally better off with higher pitch, just opposite to what I like, slower speed but more torque with this type of model.
I only had one short 4 min. flight , it seemed just right for any pattern type of aero routine, but next session I'll push it bit harder to see if it hangs on and pull out of hover with this light load prop. At later stage I'll try 23x10 Hawk prop I have in stock but will have to order Wess 24xB/10 which might probably be the best for my set up.
To get my full confidence with this model I have to see how the ESC will handle it over the next few test flights when I push it little harder, also after all these years flying it as an " IC - vibrator", the frame is not really design for hard flying, it could easily fall apart so nice and smooth touch is my idea to enjoy it, Cheers.
I got a little footage of the flight but the quality of my videos are real crap, I got some issue with my converting.
2016 1119 173758 046 (3 min 53 sec)
(Extra time maiden)
Sep 06, 2018, 02:34 AM
Thread OP
Took it out for few flights this morn, rather nice day before the cold windy snap showed up again! Pretty happy with the performance so far.
2016 1127 163334 042 (5 min 31 sec)
(Extra time)
Sep 13, 2018, 03:25 AM
Thread OP
After bit of initial radio binding problem she was up again in perfect conditions.
Next flight will be with larger 25x8 prop.
Sep 15, 2018, 02:57 AM
Thread OP
Still waiting for the larger prop by snail's mail to compare.
2016 1204 163517 0422 (4 min 25 sec)
- another sunny day.
Sep 19, 2018, 12:56 AM
Thread OP
Just received new 25x8 prop, but before testing it I checked again static pull of the 23x8 I had 5 flights with, so far. I was quite surprised when the pull increased from my first test few weeks ago which was recorded at ~9.5 kilos.
Today test recorded 12.2 kg. confirmed with the use of digital and manual scale. I'm not sure if this dramatic increase is due to the well run in motor or slightly warmer, but identical set of batteries I have used in both tests, (12S/5200/60C).
After prop balance check I have installed this larger diameter 25x8 and recorded 15.75 kilogram static pull at some 6.7K/RPM. After 4 minute ground test run on 1/2 to full power throttle setting simulating short flight the ESC barely warmed up and motor was slightly warmer but comfortably held in hand to no more than 50deg. C.
Rather impressed with these figures, but noticing dramatic noise difference with this larger prop, and looking forward to my next flying action which might take few more days due to some horrendous windy conditions we are currently experiencing.
Sep 20, 2018, 03:24 AM
Thread OP
For safety I painted the prop tips, it's nice to see the white circle rather than nothing at this power level.
Sep 22, 2018, 03:29 AM
Thread OP
Another great day out with Extra this time testing new 25x8 prop, lot quieter than static testing in my backyard, great power and very little heat recorded in motor and ESC after easy flying.
I have also used lighter set of 12S/5000/60+C batteries in one of the flights but I do notice it lands heavier than my old 2 pound lighter IC set up.
While testing bit of hover my Elevator needs change of the links geometry with not enough travel authority. Love it!
Sep 23, 2018, 01:32 AM
Thread OP
One of the test flights using the larger prop.
2016 1213 163213 0441 (5 min 25 sec)
Sep 26, 2018, 01:45 AM
Thread OP
While recharging my batteries for the next flying session , the 6S/5200 took some 2850mA and 6S/5000 , 3250 after my last flying sessions with the new 25/8 prop.
So when I'll start pushing it through some harder 3/D sessions I might expect only some 3-4 min. flight time just about the same as any of my high powered EDF jet as I never like to go bellow 30% capacity of my packs.
Sep 28, 2018, 01:58 AM
Thread OP
Bad luck today, driven all the way to the Club, but no fly, too windy 90 deg across the strip.
Took reading of the new prop power set up , pic.
Oct 01, 2018, 02:13 AM
Thread OP
Much nicer day today, the public holiday with light Southerly, even managed collision with the ibis, tho flying a jet model.
2016 1222 161836 047 (5 min 12 sec)

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