Nitro vs. Electric SSC

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dditch
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Nitro vs. Electric SSC

Post by dditch »

I went through my first season of SSC combat last year. In the fall, I also joined 2548 as well in 2 contests.

I started with Electric and finished using both Electric and Nitro.
I plan to maintain flying mostly Electric but will start out the year also having a Nitro as a backup.
I started out using Monster Power .15 motors and 2 3S 2200 packsand a Volcano or Plush 40A ESC but found that the efficiency of the Monster power was not that good and it was slightly heavier. The Volcano/Plush ESC at 40A rating somtimes died on me in a mid air impact that was enough to break a prop. I later switched to the Turnigy SK 35-30 1100Kv motor like most other people running electric.
I also switched to the cheap Hobby King SS 50/60 ESC and so far it has survived 2 mid airs where the props broke and the ESC is still working fine.
Motor : http://www.hobbyking.com/hobbyking/stor ... oduct=7075
ESC: http://www.hobbyking.com/hobbyking/stor ... oduct=7339
Spare Motor Shaft : http://www.hobbyking.com/hobbyking/stor ... oduct=8962
BEC : http://www.hobbyking.com/hobbyking/stor ... duct=10312

For Batteries, I have an assortment. I always use 3S 2200mAh but I"ve flown
Nanotech 25C,Gens Ace 25C,Turnigy 20C, Turnigy 30C
The advantage of the Nanotech and Gens Ace is that I can parallel charge them in 10 minutes with my iCharger 3016B and Deep cycle marine battery.
I put the Turnigy 20C batteries into my 3rd and 4th string planes as backups in the event I have something happen before launch.

My 2 favorate planes are the electric version of Kirk Adam's Rapier. What I like about it is that the batteries are in the fuselage and well protected. The foam and coroplast fuse is also very light and streamline. The wing is VERY efficient in a turn. Right now I have 2 of these fuselages.
I modified a battle axe and put the batteries into an elongated fuse but I find this plane flies slower.
I also have an eCobra (eFalcon with a horizontal stab). It flies as fast as the Rapier in straight flight, but not as well in a turn. Putting batteries in the wing leaves the battery exposed in a mid air and I battery last year in the eCobra while using it in only 5 rounds total.

I recently have been using an Eagle Tree Logger looking at RPMS and current draw in the Electric. What I found was that once in the air, the Electric may unload and increase only about 500RPMS. But the current drops 10-15% in the air. I did this test with the Good Gens Ace batteries so results may actually get BETTER with weaker batteries as they increase voltage more under a drop in load. But with the Electric, the RPMS in a climb or tight turn remain pretty consistant. At the end of 5 minutes, I was at about 17,200RPM in straight flight and 16,750RPMS static on the ground.

I also hooked up an Eagle Tree logger to my Nitro and an optical pickup. It was really cold in the morning and my engine was leaning out on me, but the RPMS started at 17,500. What I found was that in a dive it would peak out at about 19,000RPM and in straight flight, it would peak around 18500-19000RPMS. Since the engine was leaning out on me, there were periods of 17,000RPMS in tight turns of climbs.

My initial thoughs are that the Electric is "never bad" but "never great" as far as performance. If I could get an ESC/Battery/Motor combo that would "unload" in the air like a Nitro, then the Electric would be an advantage to reliability and consistancy. Governing the motor MAY help some in consistancy as which was pointed out by William Drum that with the extra load, the Electric motor will drive the current needed to maintain RPMS. One thing I can do is to compare an ungoverned motor with some streamers attached. I rarely see more than 3 streamers attached to my plane in combat :(

Most of the batteries and the charger I have were purchased for my other Electric flying so my initial costs for that were absorbed through the rest of the hobby.

Nitro:
Pros:
If you are familiar with Nitro and not Electric, there is little more to learn.
Potential to unload in the air is higher.
Once tuned properly, you are likely to get consistant flight performance
Cons:
If you have not tuned the engine properly, you will get inconsistant flight performance,maybe worse than an Electric
If your engine is not running well, you have a higher risk of not making start of combat.
You have to tune the engine each day of combat.
That oily mess to deal with.

Electric:
Pros:
Consistant performance during combat provided a consistant battery charge.
Likelyhood of making "start combat" is extreamly high if you test your equipment 5 minutes before hand.
You can test the motor at home in your basement with proper saftey precautions.
If you bury a motor into the ground, your going to lose a cheap $16 motor (with proper protection of the ESC).
Quick to repair at the contest if you have swap parts (ESC, MOTOR)

Cons:
In a mid air, you may lose the motor ($16 loss and repairable between combat rounds) and not be able to re-enter combat even if you can swap the prop in time.
Your Peak RPM during combat will not match the Nitro.
You need to invest in experiance of Electric flight as well as charging equipment

Last year in 30 rounds, I burnt up 2 ESCs and 2 motors. Those 2 ESCs were the original Volcanos or Plush ESCs. for a replacement cost of $60. The motors were the Monster Power. I also took out a Nitro Carb in the fall for a cost of $35. We'll see what happens this year.
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Dane McGee
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Re: Nitro vs. Electric SSC

Post by Dane McGee »

dditch wrote:............................... using an Eagle Tree Logger................... I found was that once in the air, the Electric may unload and increase only about 500RPMS. But the current drops 10-15% in the air. I did this test with the Good Gens Ace batteries so results may actually get BETTER with weaker batteries as they increase voltage more under a drop in load. But with the Electric, the RPMS in a climb or tight turn remain pretty consistant. At the end of 5 minutes, I was at about 17,200RPM in straight flight and 16,750RPMS static on the ground.

.................... an Eagle Tree logger........ RPMS started at 17,500. What I found was that in a dive it would peak out at about 19,000RPM and in straight flight, it would peak around 18500-19000RPMS. Since the engine was leaning out on me, there were periods of 17,000RPMS in tight turns of climbs.

.
Thank you for posting this info. That is excactly the information I was wanting. :D
Dane "Mad Max" McGee
Greenville, Texas
RCCA Vice President 684
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

I got a better data recording now.
This is my Hobbypartz .15 Nitro. It crashed in combat last fall and I put a Magnum carb on it (kind with the blue insert).
Winds were 10mph when I got the recording so that may have affected the high G banked turns.
The Eagletree sensor is optical. Natural light messes it some so I have it sheltered but you can see one sensor drop out on the recording when the sun came out of the clouds.
There is still some variation to the readings where in the cloudy light, it jumps some 2-300RPMS, but I feel they are pretty accurate compared to my Tach.
I started the engin in a sheltered area and set the needle valve, then took it to the flight line. Held it up for a bit (I was downwind at the time).
Then hand launched and did:
Flat altitude soft oval circuits
High G Loops
(dropped throttle to mark position on log)
High G Banked turns
High Speed Dives(Reverse Cuban 8's) You can see the peaks of over 19K RPM during the dives
Land
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

I designed a circuit that will measure current like a WattMeter then adjust the throttle to keep it constant.
Unlike governing RPM, this will allow an electric motor to hopefully unload in the air like a Nitro.
The firmware is not done yet but I'm working feverishly to have it ready to try out saturday morning at our clubs SSC / 2548 contest.
When I have it done I'll Eagletree log it to compare RPMS in flight to the Nitro Logs I took.
the circuit goes in between the RX and ESC as well as between the Battery and ESC.
Hat Trick
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Re: Nitro vs. Electric SSC

Post by Hat Trick »

Doesn't sound legal to me? How would a CD know that it's not set to tach 17,5 on the ground and be 19 in the air?
Mike Fredricks
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

I'll be showing to the Club CD (Kirk) before the contest. I hope to get an eagle tree log so I can compare it to the Nitro.
It should be very close.

The Nitro unloads to near 19K in the air and I think other people's Nitros unload more than mine.
IT will tach at 17,500 on the ground and be at or below that when I land while taching on the ground.

I just finished up the firmware tonight (midnight) and tested it on a pack. It held nearly the same Wattage during 5 minutes of run time. It dropped a few % but nothing like when running straight. The RPMS static whent from 17500 down to 17200 by the end of the pack.

If the rain does not hold me back tomorrow, I'll get an eagletree log of it. If not then, Sat morning and I'll bring my Laptop to show the CD.
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Don Holmes
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Re: Nitro vs. Electric SSC

Post by Don Holmes »

[quote="dditch"]I'll be showing to the Club CD (Kirk) before the contest. I hope to get an eagle tree log so I can compare it to the Nitro.
It should be very close.

The Nitro unloads to near 19K in the air and I think other people's Nitros unload more than mine.


What makes you think that David ?
Is someone going a lot faster then you ? :~)
Don Holmes RCCA #957
Mid Atlantic Combat
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

HAHAHA,
Everyones going faster than me except when I'm running to my charger :)
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

I test flew my circuit that regulates the current to the motor brefore the Frenzie at Freestate.
Test aircraft was a Texas Flugewerks eCobra (eFalcon with a horizontal stab)
I was using weaker 20C batteris and the batteries were not enough to keep up with the current regulation.
http://www.mycoolheli.com/PICS/sscregwe ... ytest1.jpg
Amps while setting 17500RPM were around 16 and Watts around 365 but during flight, the Amps never really kept up.
RPMS were around 18000-18500 during the flight. Low C value of the batteries were evident in the over 2V drop under initial load.

I then ran some strong Gens Ace Batteries on test #2.
Results were much better and I did that flight at the same time that another Pilot had his Battle Axe in the air running Nitro.
His engine was running Rich he said so he was running a tad lower RPMS than he should. After I took off I was doing low passes in an oval circuit, then I was trying to fly just above him and level as he was flying parallel with the runway. We both agreed that my plane was flying faster but only slighty. I estimate that I was closing about 2-4' across the 300' runway.

The current regulation software was not running as tight as I want it to run, it was allowing too many peaks and valleys as you'll see in the log. At the end I did some continuous tight turns to see how the RPMS matched when flew the Nitro.

All in all, I"m happy with the first test. I want to get the regulation tighter which will keep some of the peaks and valleys out and a more consistant run. I'm confident that this circuit puts the performance of the Electric on Par with a good running Nitro in terms of how its unloading in the air.
My test setup was using a FlySky Tx/RX setup, I had problems with the circuit working on a Spektrum Rx so I did not fly the circuit in the contest.

In the log files, you can see me setting 17500 at the beginning, then after launch (I launch at about 3/4 throttle), the RPMS unloading. When I landed, I ran the plane up when I picked it up from the field to log the static RPMS (about 17,250). Then I took it to the flight line and tached it at about 17,200. Note that the Eagletree logger picks up RPM spikes. Those spikes are not real, but it logs it that way so you kind of have to look at the average when you see those spikes.

http://www.mycoolheli.com/PICS/sscregst ... ry1ALL.jpg
http://www.mycoolheli.com/PICS/sscregst ... ry1RPM.jpg
http://www.mycoolheli.com/PICS/sscregst ... ery1AW.jpg

The contest CD saw the log files and he approved it for use in the contest, but I decided it was not ready for use in a contest. I ended up flying 4 rounds with my Nitro setup and 2 rounds with my standard Electric setup.
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cherokee180c
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Re: Nitro vs. Electric SSC

Post by cherokee180c »

Dave, I think the circuit works well, but is set about 500 rpms high currently if you look at the graph. If you remember in our test flight down low you were just slightly faster than me, which was probably that difference. You have done a lot of work to get a reliable system. Great contest by the way!

Dave
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dditch
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Re: Nitro vs. Electric SSC

Post by dditch »

yes it does look like I was at 18000 on launch, but I don't launch at full throttle with the electrics, so you may not see it run up at 17500 before take off. the logger does jump around alot thus I still have to test with a tach.

I think I need to do the test again. Next time I'll run up to 17500 with a tack just before launch to verify.

I think I may hit exit instead of menu on that cheap radio which negates the travel adjust settings.
That's not the normal radio I fly with.
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cherokee180c
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Re: Nitro vs. Electric SSC

Post by cherokee180c »

Are you feeling any better?
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