What would the ideal electric class look like?

This is the thread to aid in development of new ideas and classes. Post working rules and gather feedback!

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wparmenter
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What would the ideal electric class look like?

Post by wparmenter »

I have messed with electrics for a while, but have not found the magic bullet to be competetive. Maybe an electric only class is the solution that a few people mentioned when I was striving to compete in the existing classes with electrics. In SSC I did come up with a competetive solution to electric power, but it proved to be too fragile which made it unmanageble in the conventional classes.
I still want to be able to use electrics so I am asking for some opinions on what YOU think might work. I will start with my thoughts on what might prove to be an enjoyable/affordable/doable framework.
1/2 A combat is probably as close as we can get in existing formats that could provide viable electric solutions. Maybe we could keep the 20 foot streamer part of 1/2 A.
The sp300/350 motors brushed motors can operate with 50-75 watts of input power, and are widely used in planes such as the slow stick and the GWS warbirds. There are also several brushless solutions that can run comfortable in this power range. I recently found a brushless motor and ESC for $50 which might be viable. That brings brushless power to an equal price point with brushed.
The GWS warbirds have a max 34" wingspan, so it might be good to allow up to 34" wingspan.
A minimum weight of 12 oz might be good.
I am not sure about cell limits, but maybe 2 lipo cells, and 6-7 nicd/nimh cells. This would keep batteries cheap, and voltages would be reasonable for any charger to handle. Maybe no battery limits if watts can successfully policed.
As far as scale/open, I don't know. I like the idea of scale planes flying combat, but that might limit the interest(it might also increase the interest). Open airframes could really open the door to cheap and disposable airframes being competetive. Fan fold foam could be an ideal cheap medium for making cheap easy to produce/build airframes. Not much on durability on its own, but with a little tape, I think it might work. I am sure though that much more durable airframes could be produced out of the typical home depot insulation.
Maybe some rpm limits would be in order to keep someone from running small diameter props to get the speed up. Maybe limit the static pitch speed to 30 MPH.

I really want to hear your thoughts if you have ever thought about this, or if you have experience in the < 1 lb. airplanes in real life flight.
thojo
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Post by thojo »

what about .15 sized stopsigns?
slam
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Post by slam »

drewjet and i have been tossing this idea for a very long time. we have been following your exploits in the existing classes.

i don't believe that electric is a viable alternative in the current classes (although i haven't really considered 1/2a).

i have always felt that a seperate class and rules would have to be created (oh no!!!!!!!!another class[:0]).

we have been flying ifo's with full contact and they are by far more durable than anything we currently fly in combat, however they only have 6oz of damage inflicting mass. i don't think ifo's would be much fun pulling streamers but they are a gas trying to hit each other with them.

we are currently looking at scale aircraft in the 36" wingspan range. 10oz +or-.

i am hoping to have a plane ready this weekend (if the holiday chores don't get in the way[:D]". it will be a scale jug. i want to take the theory to the max as far as fuse dimentions. we'll see how she looks and flys.

i like the idea of a scale electric class, if we can handle the durablility issue it would look alot cooler than a bunch of open planes and would iliminate the problem with open we have of the design of the month syndrom.

slam
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boiler
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Post by boiler »

I have watched electrics fly and considered how we might have REAL combat rather than Zagi full contact stuff. I forward prop design is a must. A smaller streamer is a must, perhaps 10-20 feet and 1/2 inch thickness on a three foot thread. I think brushless must be permitted due to the long life. The brushed motors are more common and cheap now, but in a couple of years I see that changing. I think a spec class is a good place to start. I suggest a 12-6 prop and a max rpm using a brushless 300 or 400 size motor with LIPO 3 cell packs. If a plane over-tached, the builder would slow it down with a series resistor on the motor. The wingspan could be restricted and NO STICKY STUFF. The fan-fold foamies look as good a design as possible.They are dirt cheap and dont't require a lot of building experience or exoctic materials. I saw some fly in a gym last night that had "side thrust generators" which were wing tiplets type structures in the center of each wing half.I may have suggested too much expence or power, but then I've only flown gas powered and would like to keep some similarity in the thrill factor. Just my $.02.
drewjet
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Post by drewjet »

After Discussions on the phone with Sheepy, forum discussions with Irone and while working with Slam, I feel that scale WW 2 ships (maybe even WW1) with a max of 36" and 35 to 40 watts, and maybe even spec a prop. I like a full fuselage and 10 oz minimum weight (with the low wattage I think max weight will settle all by itself). Pull a 20' streamer, allow sticky stuff and put up as many planes a s frequency control allows. I don't like the profile planes, and I don't like the idea of 1 on 1 combat.

I have built so far 2 planes, the first was too big and too fast. The next one was close in speed to where I want it to be. Next one will be closer to scale.

Image

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jj
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Post by jj »

I can see a 26-36" span limitation but I'd leave the motors open a bit. At least wait until there is some momentum. I'd like to allow as many people with electrics to try out combat as possible rather than ruling them out right off the bat.

I would be using a 2015 brushless and would prefer a foamy.
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Post by wrnstockwel »

Ive put a little effort into trying to come up with a cheap 2548 electric plane. The BF-110 turned into a nice flying plane, not as fast and but only 2 oz heavier than an equivelant gas version, my FW-190 profile is close in weight. Neither plane is as fast, however they are both good flying planes, will do loops and rolls and are just as durable (airframe wise) as the 2548 gas planes.

Here is my suggestion. Take the 2548 rules, replace the .25 engine with a 7.2 volt speed 600, 2.5:1 gear box, APC 11x8.5 prop and 10 2500mAH A cells or 3s 2400 lipo batteries.Limit the prop rpm to 8K or less and allow burshless, if someone wants to spend the extra dollars for durablilty.
I have some 1800 and 2200 CBP batteries that Im experimenting with for time and performance. For the twins, use 3s2p 2400s or something in NmiH. You can use existing airframes designed for Gas, the same weight minimum, the speed would be ~6-10 mph less, so less damage from impact, and have a really nice plane. I have had a couple of gas combat pilots fly my planes and they were impressed that it could be as close as it was, without brushless or lipos. The battery packs are cheap and can be charged at 1C safetly. If you luse a larger than necessary Lipo Pack, all you will have to do is top it off between rounds.
Ill post pics of my planes here, since I now have a digital camera, and you can check out the 2548 thread for some pics that have already been posted.

If someone would like a set of wings and fuse to duplicate my experiments, or just try them out, let me know and I can cut you some.

Scott
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Post by jpmorere »

Not a bad plan Scott. Using the CBP 2500 A cells, prebuilt packs look like less than $40 each. Allow 10 NiCd or NiMh, or 3s LiPo. 600 can motors are cheap, and Great Planes (ugh!) has a really nice cheap gearbox.

The 2548 airframes do seem to be good performers, and appear to do quite well with the 600 power package. We will have to experiment a bit to further nail down the specs, but I think this proposal is pretty close.

Spec prop & RPM is a relatively easy way to check/limit power, although battery/motor/gearbox combos could be selected to unload more in the air. This is limited by the 600 can motor requirement. Maybe use a clamp on ammeter and limit the max amps? With the cell count (voltage) limit this would automatically limit watts. Not too tough to check, and would limit the systems that are set up to be overloaded static in order to unwind to much higher RPM in the air.

Several things to think about, but overall, a very good start. Maybe not THE electric class, but an idea worth checking out.
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Post by wparmenter »

I have been messing with the endoplasma, and it looks promising as well. One advantage is it has bigger and replacable brushes. I have run it with a 2.5:1 gb and a 10x6, and it was able to handle it fine. I believe the static rpm was around 9500. Watts were around 350. This was with gp3300 8 cell packs. I need to run it again to get definite figures. This makes 2548 look even more attractive.
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Post by wrnstockwel »

The numbers do look good, in motocalc. My luck with 550 car motors has not been that great, it seams the commutator gets fried pretty quickly when you exceed 30 amps current draw. MotoCalc predicts 40+ on the motor. Not saying it wouldnt work, but would have to see it flown a few times.
Try this on for size, bump your cell count to 9, change the prop to an IC 10x3. This will up the thrust and lower the current draw. Looks like I need to get my hands on an Endoplasm and give this a try! Moto calc, if your using it, will tell you the airspeed of the plane will only be 20 MPH, however the prop speed is 24mph faster than that and the prop rpm is 15K, which is in line with the IC prop rpm. None of the IC planes I have seen fly have exceeded 14,500 rpm on the ground and most were closer to 14,000 rpm and flew great!
I had dozens of flights on my BF-110 with 9xGP3300, 2.5:1 gearbox and 11x8.5 prop and 2 cheap speed 600 motors in parallel. They were still going strong. As a side note the gear boxes from Great Planes (the electrifly GD600s) have proven very reliable and durable. Worst Ive been able to do after many test crashes (to many) is strip the spur gear once, because I did not cut the throttle in time. Its a $3.50 part and takes about 5 minutes to replace. If you would like I can email you my motocalc results on your setup and mine as well. If the endoplasm would hold up 350 watts it is close to competitive with a gas plane, very close.

Obviously simpler is better, if a prop is spec'd with max static RPM, and a total cell count like 3s for lipo and 10 for Nicad or NiMH then there would be some flexibility for those who wish to invest in brushless or newer battery technology, but no major advantage.
Let me know if you would like an airframe, I can send you one of my P-51B/C fuses and wings that are already cut, with some rough instructions.

Scott
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Post by drewjet »

Scott and Wes. Those do look promising. I think in the end, no matter what you try, the power to weight ratio will never meet what the nitro planes are doing, then factor in the durability issue and there is just no way you are going to be equal to Nitro. I wish it was different, but I don't think it can be. I really believe we need to start with a clean slate. Take the existing flight rules and start a whole new electric only class.

To keep electric affordable you need to stay small, under 15ozs. Slam and I have proved that it can be done. We still have some refining to go, but we are zeroing in on some great airplanes, that are good looking, light, cheap, and durable.
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Post by wrnstockwel »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by drewjet</i>
<br />Scott and Wes. Those do look promising. I think in the end, no matter what you try, the power to weight ratio will never meet what the nitro planes are doing, then factor in the durability issue and there is just no way you are going to be equal to Nitro.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

I will agree with the fact that the performance will not be equal in the near future, run time at reduced performance and inexpensive yes, 5 minutes can be achieved with $37 battery pack and $35 worth of motor and gearbox.

As to the durability, these planes that I am flying, are built exactly like the gas version, but they fly 10-15% slower, so survivability actually improves!

Ive got nothing against using the GWS 350 gear boxes and building smaller, lighter planes, I'd like to see the results as I have had many discussions with people about a WWI class based on the same power system and 36" span.

The 2548 class was written with the hope that electrics could compete, but without throwing a large amount of money at it, you just cant quite get there. I intend on competing in 2548 this year, with electric planes, its all just for fun.

My thought for basing a class on existing rules, creating a 2548 Electric Only or 2548E class, would be the existance of kit manufacturers and kits, who through increasing their volume and constant improvement via "real world testing" could afford to supply us with really nice, durable, kits.

Scott
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Ed Kettler
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Post by Ed Kettler »

I can see an electric-only version of 2548 working pretty well. The planes are large enough that they fly on the wing instead of the prop, and they are pretty durable. Scott has a Me-110 that is a sister ship of my twin OS .15LA powered ship, and I'm quite envious of his starting procedure. We can also reduce the Start Engines - Start Combat cycle time down to about 30 seconds if we get everybody on the line, possibly increasing the combat time to be closer to the 5 minutes ICs use.

I've also thought aloud about a WW I combat class ... this would be ideal for electrics, especially fan folds. Speeds are not too high, and the wing area could support a modest power plant.

I see electric combat as a broadening of the participation in combat, and a broadening of the membership in RCCA.

Happy Holidays!
Ed
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Post by jpmorere »

Drewjet: Scott's intent a couple of posts up WAS to introduce an electric only class based upon the soon to be popular 2548 class. Replace the glow engines with electric power systems within limited specs and fly! I think that the 2548 airframes should adapt well to this change - that has certainly been our experience so far. This might manage to increase the intrest in the 2548 airframes (and kit manufacturers).

I also like the idea of the GWS-350 class planes. I think that something in the 32-34 inch range with a 350 B or C gear ratio and flying weight in the 11-12 ounce range might be pretty good. That would give a thrust:weight ratio close to 1:1 and wing loading low enough to make reasonably slow and easily flown planes. Might need to seperate monoplanes and biplanes (ww-I and ww-II), but that is yet to be seen. If the wing areas and weights are the same (same wing loading) then performance should be pretty similar. These planes would be cheap to make and to maintain. $30 of blue fanfold foam will make 18-24 models, and they can be built quickly and easily.

Let's play!
J.P.
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Post by Rabbit Leader »

My buddy Brooks and his wife Amy came over tonight. After dinner he and went into the 12th Pursuit R&D works to discuss modeling, cars, etc, and electric combat was one of our discussions. He's been flying electrics for some years npw, he's the "official" Zagi demo pilot at Mike's Hobbies. He started flying about a year after I did, and has flown a lot of slope, electric, and high speed on the edge IC models. He thinks that a 2548 plane, running a good .25 at over 14,000 with a 10-3 ist putting out somewhere near 600 watts..little over half a horsepower. Only way to get there with an electric single is to go brushless and Li-po, and that's way too expensive to put in harms way, plus you add a good hit in the right place and you might have a lipo cell short, and although it would make a cool video, a smoking 2548 bird coming in IFE would probably dampen your spirits. Now, I've flown a bit of electric, but not much. Guess I'm a die-hard "slimer". I flew scott's FW-190, and it was okay, but I didn't get a good idea of what it could really do due to a bad pack, but I think he's close. I really want to see what his bird will do with an Endoplasm up front. It would be really cool to see an e-bird that could fly with the current crop of 2548 planes, be competitve and relativly inexpensive to outfit. Anyway, I've been thinking about this for some time, and Brooks and I came to some interesting conclusions..

1. Keep it cheap. No brushless, hot setups, Lipos, etc. Keep the learning curve resonable for those pilots who have not yet been introduced to E-power..I know they're rare, but they are out there.

2. Use the same basic scoring system used in all the RCCA classes to date. No use reinventing the wheel, same scores for cuts, flight time, etc. Keep it easy..

3. Get some designs built and flying, using off the shelf components that are readily available, and for now, build an open-style combat bird with cell, motor, and possibly gearbox and prop restrictions. SSC without the IC.

4. Pimp these planes wherever you can, take a couple and tie on streamers at the lunch break at an RCCA event, fun flies and electric only events. I can not stress this enough, when I built the first prototype 2548 plane, we didn't have much interest till it was flown by several members of the local combat community. It didn't REALLY take off till Ed took his fleet and handed them out and said "have fun!" People need to see tangible evdence of what your promoting with there own eyes..not on video, but right there in front of them.

I really think a good e-class would draw more members into the RCCA, as I have talked with members of the DEAF club, and they like the idea of combat, but not with glow engines. Give 'em an e-class, we just might end up with more combat pilots to fill our ranks.

Cash
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