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Old Mar 14, 2004, 10:53 PM
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Joined Sep 2003
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Combat Electric vx Glow Combat

Ok, it's finally happened! The "Glow Fuel" guys are getting together a couple of combat planes for the fun of it. They've laid down the challenge for me to build an electric combat plane that can "hang" with them. They think they're being cute, but I would really love to give them a good butt-kickin'.

Does anyone have any ideas or plans for a 15-25 sized combat plane with a motor/gearbox/battery combination that would work. I think a couple of lithium packs and a brushless motor would be able to drag a streamer quite well.

Just think, while they're fueling up, cranking and trying to get off the ground, I'll be already in the air, waiting for them!
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Old Mar 14, 2004, 11:44 PM
I hate waiting for parts
Mike_Then's Avatar
United States, NC, Garner
Joined Apr 2001
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.....and you won't make it to the end, as you're plane will run out of juice halfway through the round. One of our club members tried electric combat with us, and had a hard time making it work. No slight on his skills, of course, it's just that the plane becomes too heavy to be competitive for an e-power system equivalent of a .25-sized glow engine. And by the time you stick the equipment in the plane to make it as fast and maneuverable as a .25 glow combat plane (such as a LiPo pack, ESC, brushless motor, and gearbox), you'll have $250 invested. That is way too much in a plane that will most likely not go home in one piece that day, IMHO.

Most of us buy Battle Floyd or Predator kits, and stick in used engines and radio equipment. Assuming the engine and radio survives the crash (which it does 9/10 times), I'm out a $40 plane but have everything else that I need to stick in another airframe. Our club's objective was to have fun at the lowest possible cost, and you just can't do that with an electric combat plane that's going to mix it up with glow planes. They have to be able to shrug off hits in the air, as well as tow a 20' streamer with a 10' string.

If your club is going to follow the AMA/RCCA rules for combat, the weight limit for the planes is 3.5 pounds for glow and 4 pounds for electric (glow is weighed dry, while electric is weighed with batteries in place). Heats are 5 minutes each, with a 90-second launch window - the round is started once all planes are in the air or the 90 seconds expire, whichever occurs first. Keep that in mind when putting together your power system.

I'm not knocking you or trying to discourage you; merely telling you of my friend's experience. Good luck, and I hope you make it work!
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Old Mar 15, 2004, 06:41 AM
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Glow electric

You've got a good point. I might not want to spend that much money, just to prove a point. I know that I can get the performance, and probably have longer duration with lipo batteries, but that's a lot of money to spend and risk tearing it up.

To give you an example, I installed a HiMaxx brushless motor and 3-cell lipo pack in an old Wattage Impress the other day. Except for the fact that there was no noise, you couldn't tell that it was electric.! It really performed that well. But I have $200 in the power system! That's ok for sport and fun, but not to destroy in a combat situation.

Thanks for the advice.
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Old Mar 15, 2004, 11:56 AM
I'd rather be Flying
davecee's Avatar
Nashville, NC, USA
Joined Mar 1999
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It can be done...but

I'm the guy Mike was talking about. Here's my experience.
Our heats are 5 minutes, I always wait till the launch window is almost closed before I launch, that saves a few ma. You really need to fly the whole heat at WOT to be competitive. You need to balance your amp draw and battery capacity to finish the heat.
I first did a Battle Floyd on 8 cells (sub C) with a geared MMR. I could get the duration (4 minute heats then), but the speed was not competive. Went to 10 cells and the plane was fast enough but with the small wing area of the Battle Floyd tight turns and loops were fraught with peril, the plane would snap out of too tight maneuvers.
Built a balsa flying plank, 600 sq. in. Speed and climb were competitive, turned OK, but not the best. Used a 10 cell geared Endoplasma. Plane was too fragile though and was lost when I launched once with the CG too far back.
Bought a used Sig Ninja, put the geared Endo on the front, mounted the 10 cell Sanyo 2600 pack on top of the wing. Plenty fast, great climb, best turning plane so far, very competive.Too fragile, torn up in a midair.
Bought a Predator, fast enough, but at the weight it just wouldn't turn or loop well, snapped at the touch of the elevator. Lost when an aileron was torn off. I think part of the handling problem was that I didn't really get the plane set up right in relation to CG, control surface movement and battery pack placement. I decided to give the electric a rest, due to frustration.
I've ordered a Slasher, and I picked up an MDS 28 to go with it. I'll stick with glow for combat for now. The Slasher looks, however, like it would do well as an electric conversion. Maybe I'll rethink this a bit later.
You can certainly do it. You probably won't fly as fast or turn and loop as well as the lightest and best of the glow planes, but you can certainly be competitive. Keep the gear cheap. I'd use a geared Endoplasma, use the Great Planes box and a 10 tooth pinion at 4.6:1. Have an extra box and spur gears on hand. Prop it to get about 5.5 minutes at WOT, use 10 GP3300 cells. With these cells you can prop for 30 amps and get 6 minutes of full throttle. Use a clean airframe that will turn well, plenty of wing area will help. Wait to launch at the last minute, throttle back ,if possible, at every opportunity.
Go get 'em!

Good luck, Dave Chewning Sr.
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Old Mar 15, 2004, 02:36 PM
I hate waiting for parts
Mike_Then's Avatar
United States, NC, Garner
Joined Apr 2001
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I was hoping you were going to see this thread, Dave, and tell of your experience. And Dezynco, please don't take what I said the wrong way; I'd just hate to see you drop that kind of money into a hot e-setup, and lose the plane (and the e-setup, most likely) 3 minutes into the round.

If you're lucky, maybe your glow guys will be using old O.S. FP engines or engines with bushings rather than bearings. If that's the case, then they are usually quite sluggish and maybe you'll be able to eat 'em up with the proper brushed motor/gearbox combo.

Good luck, and please keep us informed of your progress!
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Old Mar 21, 2004, 02:02 AM
Dizzying Heights
SargeNZ's Avatar
New Zealand, Southland, Invercargill
Joined Feb 2003
1,063 Posts
reviving the thread here.

If u guys are worried about fragility in your aircraft then build the wings from foam and the fuse from coroplast if you wish. A foam wing will never break if its properly done and this type of construction is dirt cheap for crashes or prototyping your designs.
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Old Mar 21, 2004, 08:46 AM
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We're not really worried about the fragility of the aircraft, that is easily replaced. The problem with building a electric combat plane that will keep up with the "glow guys" is the cost of the electric gear. Brushless motors, speed controllers, and batteries are expensive. Would'nt want to damage them in a collision, and the plane will probably go down - in flames - if the battery shorts out!

As far as sport flying and 3D stuff, I'm an avid electric man. No messy fuel, and in the no-so-long run, it saves money.
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Old Mar 21, 2004, 08:51 AM
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Bye the way, I told the local hobby shop owner about the idea. He is also an electric fan. He's thinking about taking up the challenge to prove that it can be done. Says he doesn't care about damaging the gear. And it would be good advertisment for his eflight merchandise.

We'll see!
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Old Mar 21, 2004, 09:02 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
4,828 Posts
Hi

yes, I have ideas! I use the international rules, they have no special limit for motor or battery as I understand it, only that the prop must be dia + pitch =13 so 7x6 it is

plane must me 1935-1945 1/12 scele.

I use a spitfire, mega 16/15/3 and 2s2p oldie kokam 3300. AUW 850grams (700g lower limit)

I can easily get down to 700g just no time at the moment.

I get 17min flights on full power, which is more then enough for the 7min heats.

useing new 10C cells and the new glassfibre spit I think I can out power the .15 easy. but I se no reson to pull away too much, that only means the rules will change to my disadvantage.

not to forget that I will get a couple of extra points for flight time as I can get in the air atleast 8sec earlier then the others useing catapult

Spitfire late summer 2003 >>>

/Henke
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Old Oct 03, 2004, 10:39 PM
Does anyone hear a cat?
headless's Avatar
Tallahassee, FL
Joined Sep 2003
4,380 Posts
Heylo Henke. I'm looking into trying to get a Slasher conversion into the air here to fly with the local glow guys. I have a mega 16/15/3 here that i was going to use, so i was interested to see the video of your setup fly. Could you tell me a few things?
(A) prop diameter, pitch
(B) RPM's, amp draw, and total capacity of your pack (is it 3300mAh or 2s2p = 6600mAh)
(C) what gear ratio you are using

Thanks for the help!
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Old Oct 04, 2004, 11:05 AM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
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Do a search for user "Sheepy" or "sheepy". He has built a successful SSC Class electric combat plane that will fly for an entire heat.
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Old Oct 05, 2004, 02:42 PM
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Joined Sep 2003
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Glow vs Electric Combat

The problem, again, is not power, endurance, or weight. With the proper brushless motor and lithium batteries, I could outperform ANY glow plane. The problem is cost, and the fact that if the lithium batteries are damaged during the inevitable crash, they could set the field on fire.
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Old Oct 05, 2004, 02:58 PM
Does anyone hear a cat?
headless's Avatar
Tallahassee, FL
Joined Sep 2003
4,380 Posts
I've pretty much come to that conclusion. To fly for 1 hour straight i'd need about 700$ of (easily damaged) lipo's. It'd CRANK the power but hour long charge times mean multiple chargers, big lipo packs mean a large investment of $$. On the plus side, i could buy the packs in smaller chunks that would also power (ALL OF) my other planes... If lipo's drop in price by... oh.. say 40% it would be feasible for me.
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Old Oct 05, 2004, 06:32 PM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
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If you are just out flying combat against your buddies that might be a problem, but at a combat meet you usually just fly (1) 5 min. heat per round. Depending on the number of pilots at the meet, you may not fly more than once every 45 min to an hour (8 to 10 rounds is quite a bit of combat in a day). So for competition combat you would have plenty of charge time with just a couple or 3 packs.
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Old Oct 05, 2004, 07:05 PM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
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I was useing a directdrive motor with 7x6APC

now switched to TP 2s2p 4200mAh and a 7x5 APC prop. weight is 701grams got the same or a tad better power then the glow guys,,, so it is a fair race! really fun
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