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Author Topic: ELECTRIC COMBAT DEMO AT BRODAK FLY-IN  (Read 1553 times)
Dennis Adamisin
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« on: June 09, 2017, 10:17:58 AM »

Visitors to the Brodak booth in Toledo this year may have spied the prototype of a new 1/2A sized combat wing - that is designed for electric power.  John Brodak ordered a 200 unit production run plus 6 advance samples for a trial electric combat demo at the Brodak Fly-In.  I took the Toledo sample home and set it up with a similar power system from my Junior Flite Streak that earned positive reviews at the Brodak Fly In back in 2014. (See http://stunthanger.com/smf/gettin-all-amp'ed-up!/jr-flight-streak/)  Test flights show a LOT of manuverability and fair speed - more on that later.  An opportunity was noted to increase the speed and keep it more constant for the flight duration.  Brodak is also getting a special motor made up for these airplanes.  Based on tests Will Hubin has prepared some special pre-programmed timers.

Bit of background on the power system.  An off the shelf EF-1 (electric pylon) racing system will turn an 8x8 prop at around 17k - for about a mniute and a half.  That's power comparable to a 60's combat engine, bolt it into your VooDoo and it should turn around 100 mph.  Unfortunately the total RTF airframe would be close to 30 oz.  SPEED KILLS, batteries that is.  Bigger batteries will let it fly longer - but at a weight penalty.  Slowing it down enables longer flight time, but you have to go deep to save any weight.  Also if we want to maintain a CONSISTANT speed, we have to start a little slower and add throttle input to compensate for the battery voltage burning off.  Going smaller and slower should enable reductions in weight and increases in duration - to a point.  So what is the best approach to balance all the parameters?

The system here uses a 8x6 prop, turning around 11,200, and maintaining that for 3.5 minutes.  Airspeed "only" about 56 mph, so we will add "quickness" by subtracting line length.  I have been flying on 52' lines, the resulting 4 second (average) lap times seem pretty quick (to a stunt flier) and the airplane handles really well with good line tension.  BUT WAIT, it did not occur to me until later that it is a 1/2A sized airplane and I should be flying it on 42' lines, with resulting lap times of about 3.2 sec.  Sound better? The RPM is way under a screaming 1/2A but it is also turning an 8" prop which should translate into steadier speed (less bleed off) during manuvers.  If moving from 52' to 42' lines it should be possible to trade off some of the lap time for greater flight duration - if that is desirable.  The prototype is flying with a 3Sx1800 battery, it should be possible to keep the same duration but trade off some lap time in favor of a smaller/lighter battery - and improved airframe performance.  The electric power system will also be infinitely more consistant than a honking 1/2A too.  Of course it will be quiet enough to fly in a school yard.

I have no illusions that Electric Combat will appeal to EVERYONE, however I hope that those who are interested will participate in improving the project.  The goal is to put these airplanes in the hands of some of the Combat flyers at the Brodak Fly In next week and get your feedbback.  Expect it will happen on Wednesday prior to the start of the combat competition.  Hoping to even fly some matches to see how it plays out.  Questions to be answered include, how viable is the package and suggestions for further improvements?

If sucessful this could (near term) turn into a single design & power system event where all of the "hardware" is about as evenly matched as possible and flying is emphasized.  We'll see...


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Denny Adamisin
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« Reply #1 on: June 09, 2017, 10:28:06 AM »

  Cool, do they come with matching Streamers?
Al
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« Reply #2 on: June 09, 2017, 10:46:22 AM »

How do you shut them down in case of a fly away?   If I wasn't so old I would love to try it. Hoff
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« Reply #3 on: June 09, 2017, 12:16:31 PM »

What voltage and capacity lipo are you using? I love the fact that it will be a combat match and a good crash will REALLY lead to an explosion  Layingdown
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« Reply #4 on: June 09, 2017, 01:02:28 PM »

Love it! I would hope it would reach a new market of kids that would be interested, but know nothing about glow motors and fear of fingers in props. I would be interested in one just to fly in my back yard.
Does it have some kind of load protection in case you hit the ground? Ive flown some electric combat. (won 75 mph twice in Tucson with the same plane) Wife will pit that one for me since all she has to do is hit the switch. Was a lot of fun!
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Dennis Adamisin
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« Reply #5 on: June 09, 2017, 02:18:06 PM »

Al: Flyers will be able to accessorize their streamer colors at contests as they do now

Doc: 1/2A Combat is excluded from the shut-off requirement, this is the same size, will need to determine if the same rules should apply.

badbill: 3S x 1800 and I hope not.  All seriousness aside, The motor is a 2816, typically this size is built with a 3mm or .125" motor shaft.  I asked that these motors to be built with 4mm shafts to add some durability.  The hollowed leading edge is energy absorbing EPP foam but there is a balsa web spar capping the back of the foam.  This should translate into pretty good energy absorption in a crash.  The battery will be most vulnerable to a midair collision.                                                                                                                                                

Bob: Your experience is encouraging to know. The ESC will protect itself from overcurrent, as all ESC's are supposed to do.  Another option will be to use CW rotation prop; on a serious prop strike it would loosen the prop itself up and let the motor spin free.                                        
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Denny Adamisin
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« Reply #6 on: June 10, 2017, 03:49:15 AM »

            I want to see what repeated ground strikes do. Has this been intentionally done?  How's the battery attached to the plane?  Does this now require a restraint for the battery as well as the motor? 1/2A can get pretty crazy, line wraps, mid airs, etc. It sounds as if engineering was designed into preventing a overload in the circuit, what about the circuit board on top of the motor? The circuit board  looks like it's just waiting to be broken off. It appears that there's room behind the motor mount, wouldn't the circuit board fit behind that or into the foam leading edge  offering some form of protection?  I don't get the Swiss Cheese elevator. That seems extremely weak for the hinge connections and the elevator itself.  In the event of a mild prop strike seems to me you would loose the majority of it to make it flyable.
« Last Edit: June 10, 2017, 04:41:56 AM by kenneth cook » Logged
Dennis Adamisin
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« Reply #7 on: June 10, 2017, 06:45:27 AM »

Hi Ken
Will try to take your point in order:

* I would be surprised to find any competitive combat model or power system would be capable of sustaining repeated intentional crashes - so lets make sure we have the correct expectation.

* Within the limits of this design I would expect the matches to be limited to the expected motor run - 3.5 minutes.  To restart requires at a minimum that you unplug the battery, re-plug, let the ESC initialize, then hit START.  I would also not expect to change packs or re-start in the middle of a 3.5 minute match.  Crashes happen, pilots have to be aware that a likely crash ends their match. 

* It has not been repeatedly crashed.  My expectation is that a crash of adequate severity will result in broken prop, then prop adapter and then a bent motor shaft.  These parts are all replaceable and will be stocked, but not by next week!  The motor mounting plate would probably be next to go.  No idea what would happen to the rest of the structure.  The leading edge is EPP foam with a spruce(?) insert. It has spruce(?) top and bottom spars and a vertical web spar.   The trailing edges are carbon strips.

* I think the battery is reasonably well protected in a crash.  Battery box is built in with a locking plastic retainer door.  It also has two Velcro retaining straps.  A 1/4" thick slice of foam rubber between the battery and the door will keep the pack from rattling around and keep the Velcro closed.  If the airplane gets "center punched" on the battery box on top the plastic door & foam cushion should help spread the impact some.  Same hit from the bottom of box hits a balsa floor, again should disperse the load and prevent it from being a point strike to the pack.

* The circuit board you mentioned is the Timer secured with double-backed foam tape - it is also possible to add screws to lock it into position.  An impact would likely destroy it and shut down the model.  I am a fan of KISS, as shown is as simple as it gets.  The location chosen was convenient (the little white rectangle is the start button) and very visible for the launcher.  Launcher hits the button then launches.  Of course other locations would be workable.  Internal location with a remote start switch would be possible (cost/complexity versus value?)

* Swiss cheese is attempt to control weight and balance.  I guess we'll see if it is unacceptably vulnerable.

I want to stress part of the reason for this demo is to see how Combat pilots can fly these models in interesting combat matches.  I honestly do not know how many of the concerns you raised will be a barrier to the success of this as an event.

Are you going to be at Brodak next week?
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Denny Adamisin
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« Reply #8 on: June 11, 2017, 05:28:32 AM »

             Dennis I'm not trying to be condescending in any way. I raised some questions because when I look at the plane, I see issues that certainly could quickly end the fun rapidly. In regards to Brodak's, I won't be attending this year due to my busy work schedule. I know pretty much all the pilots flying combat there. I mentioned the holes in the elevator, while this is a moot point if nothing happens certainly this is not a barrier.  I refer to this type of elevator as a whale tail. The problem with whale tail planes is the stress the elevator is put through in just flying normally, they tend to flex and dicing holes into it presents even further flex. I just feel from a sideline point of view this is a potential failure in the future.

 The strength lost and weight saved there is not worth all that sacrifice in my opinion. If the plane is tail heavy, slide the battery pack forward and utilize the strength. These are not stunters, tails and wingtips are subjected to a lot of damage. The first gen Gladiator was also tail heavy which made it a HUGE problem for those not familiar on how to deal with it. While this subject is not about the first one nor do I want it to be, I'm just finding it interesting that here we are again with a design that came out  tail heavy.  

          I'm not flying the plane nor do I have it in front of me I'm just offering my opinion.  The run time is concerning as well, I'm certain this is in it's early test stages, but I feel that needs to be increased. Putting a larger prop on there somewhat throws a flag because while it governs your run time, I feel it's going to adversely affect the turning rate of the plane. People today are almost governed by instant gratification . They feel if they buy it, it must work,  but  no one  likes to do  additional work to make it work.

        
« Last Edit: June 11, 2017, 06:58:44 AM by kenneth cook » Logged
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« Reply #9 on: June 11, 2017, 07:44:10 AM »

We have a pilot around here that has been converting old combat designs to electric.   He is having fun with it, but I am not sure exactly how successful he has been as far as placing. But he is flying against engines.

 I had converted a lil Satan to electric and it worked great.  I had an inrunner motor installed though, and one ground strike broke the output shaft off of the motor.   I pretty much decided then that an outrunner style would be the way to go.   In an article by Rudner, he had said he was unhappy with the way the outrunner powered planes turned.  All of that spinning mass affected the airplanes turn in one direction. 

 I will be watching this, as I am sure we will see some more activity with electric combat. Possibly a specific class.  I especially think something in the 1/2A size would be a lot of fun.   Good luck with this.
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Dennis Adamisin
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« Reply #10 on: June 16, 2017, 07:21:06 AM »

So the Combat demo at Brodak is in the books.  THANKS to all that participated.  Got some great feedback, an a mix of very good to not-so-good results.  I'd ask that any who participated add their observations:

The GOOD
The airplanes fly very well.  Had about 15-20 flyers (lost count as I kept running in to the shop to charge batteries) Did not get any negative comments about the flying - lots of grins!

Started out on .012 x 42' lines, then graduated to 30# spectra x 42' lines - better. 

Speed was a leisurely 3.7 sec per lap but with the 8" prop the thrust never quits - in tight maneuvering it will slow some but keeps digging leading to good speed retention through maneuvers.  As an example, Phil Cartier started flying maneuvers downwind, then quickly moved to upwind (albeit a pretty gentle breeze) with no loss of performance. One guy commented it was like old-time slow combat for 1/2A sized airplanes. They are slower but the keep flying.

Performance with the streamers attached did not result in any noticeable reduction in performance.

The power system consists of a simple non-governing ESC and a "throttle-up" timer which starts at a lower throttle setting then steadily increases the throttle setting to 100%.  The result is that the speed is held constant for the duration of the flight. It works very well - lap time at I minute into flight was within .05 seconds of lap time at 3 minute mark.  Several comments that speed was very constant.  Nobody said they had any problem with the 3.5 minute time limit.

Started with a 3Sx1800 pack, then determined that a 3Sx1300 was adequate - that scores about a 1.5oz weight save.  Because the 1300 battery is smaller I put a shipping peanut into the end of the battery box to shift the battery weight less outboard to mostly nullify the excess "wing tip weight" issue associated with the battery.


The NO BIG DEAL
Most were test flown on the field and found the usual issues with slight wing warps & such.  The warps did not really interfere with flying, and several airplanes got a heat-gun fix on the field.  Also determined some difference in turning inside versus outside.  Upon further review this should be trim-able by resetting the elevator neutral to assure correct throw in each direction This kind of trimming sounds like SOP for any airplane.


The NOT SO GOOD
The first crash resulted in a broken prop and dirty motor - no damage to airframe.  The next crash was a mid-air that resulted in broken wing that flew for a couple minutes before failing.  The third crash broke the spar in the center and ejected the battery box - no damage to pack.  The X-Plate to motor screws were too short (my bad but preventable) - had one failure at this interface, then a second when a prop sheared and vibrated the motor off - this is an easily fixable problem.  The motor mount & center rib structure was not damaged in any of the crashes. Still doing post mortems but it looks like none of the crashes destroyed motors, ESC's or batteries.  Might cobble pieces from two wrecks to salvage one - TBD after I decompress...


CONCLUSIONS
Everyone agreed they could fly combat with these airplanes.  The crashes revealed some durability issues - the airplanes do not bounce very good!  The power system worked very well and could be used on similar sized airplanes with good results.  These airplanes also should not be mixed with high performance nitro 1/2A's - but that was not an expectation in the first place...


Once again, THANKS to all who participated and offered their feedback.


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Denny Adamisin
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« Reply #11 on: June 16, 2017, 10:49:44 AM »

Sounds like Brodak may have something for a one design/motor combo for us to play with.   I guess they all ran about same air speed.  Has he listed them on the site yet?
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« Reply #12 on: June 16, 2017, 02:13:20 PM »

             Upon my initial reading of this, I really wasn't certain as to what audience this new plane was designed to capture. Now reading the posts it sounds like this is certainly not something that could be used on a competitive level.  One thing that we still don't know and it would be the first question anyone would ask is how much does this cost? RSM sells a .061 equivalent complete system which is $140. If your saying that these planes have a lesser equivalent in power, one could only assume the system is less expensive?  Ken
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« Reply #13 on: June 16, 2017, 06:51:28 PM »

How do you shut them down in case of a fly away?   If I wasn't so old I would love to try it. Hoff

They fly well under 75 MPH so flyaway shutoffs are not an issue.
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« Reply #14 on: June 16, 2017, 07:05:20 PM »

I flew one of these and it was very nice.

The current quoted price was  $75 for the airframe and $75 for the motor & electronics.  Batteries & charger are more.  So it costs about $200 all up for Unit One. It won't be cheap combat.

The Brodak combat demos busted up a lot of stuff.

In practice, the Small Electric airplane could be built for $20 and patched-up when damaged.  Some of the electrics might be salvaged after a collision.

A current Ukrainian F2d costs about $350 all up.  Of this about $60 is lost in a crash. 

A Speed Limit Combat plane with an OS 25 is worth about $160 and the minor crash cost is about $20.

The Small Electric has the advantage of known performance even in the hands of a beginner.

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« Reply #15 on: June 17, 2017, 05:18:21 PM »

Thanks for the info, I can't wait to try one.  Like everything else, this will get better with time. More airspeed, more airtime, better flyability, better crash survival will all come if we start to play around with the setups and technology.

How loud is the setup? The thing that makes me most interested is the possibility to fly in my backyard again without disturbing the entire neighborhood.
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« Reply #16 on: June 18, 2017, 07:50:40 AM »

Thanks for the info, I can't wait to try one.  Like everything else, this will get better with time. More airspeed, more airtime, better flyability, better crash survival will all come if we start to play around with the setups and technology.

How loud is the setup? The thing that makes me most interested is the possibility to fly in my backyard again without disturbing the entire neighborhood.
  Very quiet Dave. No problem flying in most backyards I would imagine. I have 2 of the prototypes and will be bringing them to the Nats for people to try.
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« Reply #17 on: June 18, 2017, 12:00:32 PM »

I'll add a couple of pennies here.  Dennis and I talked several times when he was setting this up.

I tried two planes, both flew just fine.  He made a good choice with the 5mm shaft and the 1300mah battery- stronger and lighter setup.They were nice and maneuverable, and except for minor trimming issues were perfect.  They weren't upset by some of the gusts, maybe  10 mph.  The strong pull from a relatively large prop makes big difference.  The design of an electric motor- diameter, length, how its wound, coils, etc. determine the speed a motor tries to run on a given voltage.  The more load applied the more current it draws so in a plane like this it keeps a pretty steady speed instead of slowing down in maneuvers.  The variable power speed control, rather than  a much more complicated governor, worked well.  The performance is very predictable from flight to flight without the complications intuning a governor just right.  I've worked with PhD electrical engineers that couldn't tune a feedback circuit like that.

These first planes would be just fine for training and sport flying.  They can't take as much punishment as a Euro style or foam wing plane.  The turf at Brodak's was cut very short and the ground hard.  Flown over decent turf 3-4in. high and with softer, damper- soil they'll be fine.  The only real problem I noticed was that they didn't turn as tight as most of us are used to- maybe 1/3 larger loops than most glow powered planes can do.

Going to a smaller 1000mah battery would save another ounce or more and give a 2.5min. flight.  That could make for a pretty clean match with both flyers taking a pit stop to change batteries in the middle of the match.
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« Reply #18 on: June 18, 2017, 02:01:33 PM »

Phil... as I follow this I had the same idea when I read about only 3~3.5 min flights

like you said and I agree..."Going to a smaller 1000mah battery would save another ounce or more and give a 2.5min. flight.  That could make for a pretty clean match with both flyers taking a pit stop to change batteries in the middle of the match"

looking forward to see these for sale,  on line----- soon??

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« Reply #19 on: June 18, 2017, 04:49:24 PM »

I would be interested in the power system at least, as I have a model that I designed for this size, but it is a foamy.   My thoughts were to use it as a demo, but I like the direction this is going.   This size could really generate some interest for combat.
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« Reply #20 on: June 19, 2017, 06:41:23 AM »

THANKS for all the commentary.  I thought it worked pretty well but what the heck, I'm a STUNT flyer!

The ESC is 30A - oversize but no difference in weight in size/weight versus a 20A - I figured extra capacity would come in handy in overload conditions.  It is a simple ESC, that's where the "throttle up" timer comes in. The timer starts at a reduced setting, but adds throttle in several steps as the flight goes on to compensate for reduction in battery voltage.  At 3 minute mark it is at 100% throttle. I started with a 1800 mah pack but determined that my 1300's were acceptable.  The 1300's were the smallest I had, but now with lots of charge data on hand it looks like a 900 mah pack should be the minimum that would work within normal Lipo guidelines (i.e., using about 75% of capacity).  The weight savings should translate into a bit more maneuverability and less energy to dissipate in a crash - both good things.

I think I mentioned this before, the timers are programmed with NO adjustable features.  The motors are all 1200 kv.  The performance of airplanes & power systems should be as close to identical as you can get.  The power system could be used on other similar sized birds - would be interesting to see; will higher performance result?

Regarding flight duration.  My goal was to fly without the need to change packs during a match and (arbitrarily) used 3.5 minutes as the minimum acceptable time for such a match.  With a "guaranteed" start and identical run duration for all, the 3.5 minutes would all be "quality" time.  I also wanted to AVOID battery change-outs made in the heat of battle - which could be done badly.  Ejecting poorly changed-out batteries is no fun.

However, if you only want to fly a 5 minute match flown in two 2.5 minute increments with a pit stop that is certainly possible.  I never timed any of them but I speculate that with the system as designed a battery change-out could probably be made in about 20 seconds.  Two possible pay-offs, with a shorter flight time it should be feasible to either further shave a little off the flight pack size (700 mah?) OR it should be feasible to start at a slightly faster throttle setting and sustain that over a shorter period.  The ability to develop good battery pit stop systems and techniques would also be an enabler for other larger classes by reducing the size of the pack needed for higher performance birds. 


Let me toss this out there.  Several comments have been made about these airplanes and power systems being usable for an entry level "trainer" kind of event - since the airplanes fly well at the current speed as is I am not sure more speed is needed.(?)  Similarly, with flight duration, for a newbie, 3.5 minutes could seem longer than it is.(?)  The power system would also be in effect "locked-down" with no field changes possible - that's good for a one-design event but bad for further development.


I think it was Bob Mears mentioned he had success with electric powered Speed Limit combat system, maybe that should be the next place to put development?  Again I am worried about battery weight and retention, but it might be workable if limited to a 2.5minute run with a pit stop.  With a speed limit, it may also be possible for electric airplanes to go head to head with IC?

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« Reply #21 on: June 19, 2017, 10:38:35 AM »



 I got to be test monkey for 4 of little critters .as said they had some small warps but it did not affect the flights at all .they were fun to fly .fully capable of doing anything you wanted to do Deff fun to fly.they will keep u on your toes
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« Reply #22 on: June 19, 2017, 11:05:35 AM »

There's nothing sacred about 5, 4, or 3 minutes.  If they run two minutes just fly two minutes.  In the absence of engine issues like starting and bad needle settings, two minutes is plenty of time to fly a match.

Given the slower speed, wider turning and reliable motor runs, there was no excuse for so much destruction at The Brodak.
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« Reply #23 on: June 19, 2017, 12:10:15 PM »

You know, it might be great having 2 1/2 minute matches.  Especially for those of us that are getting up in years. Hoff
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« Reply #24 on: June 19, 2017, 12:51:44 PM »

I like to think some of the getting them to run for a full 5 min combat match has a lot to do with all the grief anytime some one wants to change a current long standing AMA contest rule

jest sayin

and of course all LOCAL beginner or higher combat matches want to deviate from THE RULES....this is OK with me

While there are still many venues where full scream loud IC motors can exist for some time in the future....the much quieter electric power has the potential to be used at places where noise is a serious concern.... like my front yard where I do respect MY neighbors
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« Reply #25 on: June 19, 2017, 03:03:12 PM »

            It sounds too over priced for a beginner . One crash and the amount of crap that breaks makes it a no go for Joe the beginner. I'm also amused by the warp comments. I find it very funny how many  recognized the warps but they were never a serious problem.  Paul, I would like to hear your input on this if you saw them or even flew one yourself.
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john e. holliday
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« Reply #26 on: June 19, 2017, 05:54:24 PM »

See reply #14.
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John E. "DOC" Holliday
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« Reply #27 on: June 19, 2017, 08:00:11 PM »

I dont think these are at all for  the real combat pilots. BUT, they are for combat pilots grand kids and friends! Many kids are afraid of these super loud combat planes and shy away from them. Although electric is still dangerous, its not as intimidating. Not to mention if they are readily available, there might be some outside interest that we need so bad. Newbies cant even buy combat stuff in hobby shops anymore. We get all our stuff from outside the USA now. And its not easy. Its no big deal for kids today to spend hundreds on drones or helicopters they crash in minutes and throw away. Why wouldn't they try this? And just maybe with the power plant being the big expense, they just might purchase more airplanes to use the power plant on. I wouldnt even try to make it competitive with fuel models. Make it more of a toy. And a two minute flight is plenty of time. Keep working on the idea. I think it has merit
!
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« Reply #28 on: June 19, 2017, 10:34:42 PM »

What are the specifications on the plane? (wingspan, area, etc.)
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« Reply #29 on: June 20, 2017, 04:27:15 AM »

Other than Stunt, I've only flown Speed Limit Combat with the Massachusetts gang (Formula GX) back in the 90's.
I wouldn't mind dabbling in SL Combat again, but I have no desire to dabble with fuel again.
Although you can have a ton of fun in 2.5 minutes, it seems like 5 minutes makes for a good match.
I would think the ideal way to set these up would be for a 2.5 minute run. Perfect for the new guys, just turn and burn for 2.5 minutes and then go laugh and watch the next pair.
For a competition where you want 5 full minutes, you have a mandatory NO PRESSURE pit stop where each crew swaps the battery. Once both crews are ready the horn blows and you're off again. No need to hurry and cut corners on battery restraints.
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« Reply #30 on: June 20, 2017, 08:08:07 AM »

There's nothing sacred about 5, 4, or 3 minutes.  If they run two minutes just fly two minutes.  In the absence of engine issues like starting and bad needle settings, two minutes is plenty of time to fly a match.

Given the slower speed, wider turning and reliable motor runs, there was no excuse for so much destruction at The Brodak.
  Two of the airplanes were destroyed due to a failed launch. A pitman launched an airplane directly into another. I know because I was flying one of the planes.
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mlondke
« Reply #31 on: June 20, 2017, 08:13:57 AM »

People keep referring to Speed Limit Combat. Read the OP, These are 1/2A combat wings we are discussing here.
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« Reply #32 on: June 20, 2017, 09:33:56 AM »

Thanks for the info, I can't wait to try one.  Like everything else, this will get better with time. More airspeed, more airtime, better flyability, better crash survival will all come if we start to play around with the setups and technology.

How loud is the setup? The thing that makes me most interested is the possibility to fly in my backyard again without disturbing the entire neighborhood.

Here is my 35 size combat converted to elect. This the plane I wont in Tucson with twice. Just wanted you to hear how quiet it is. All you can hear in a match is the streamer flappin'

https://www.rcgroups.com/forums/showthread.php?1795742-Elect-speed-limit-combat#post23626167
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john e. holliday
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« Reply #33 on: June 20, 2017, 11:02:35 AM »

May get planes flying in parks/ball diamonds where people can see them and not complain about the noise.  Is there a post on here of your set up? Hoff
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« Reply #34 on: June 20, 2017, 01:05:01 PM »

May get planes flying in parks/ball diamonds where people can see them and not complain about the noise.  Is there a post on here of your set up? Hoff

Theres a picture of it on a blog      https://www.rcgroups.com/forums/member.php?u=387956    have to scroll down to find it. I have all that info somewhere but cant find it now. Havent messed with it for a couple of years. I'll get it out and jog my memory and post it back here.
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« Reply #35 on: Yesterday at 01:00:13 AM »

Hi Dennis,

As always..........you did a great job of electrifying something new! I played with this last year, but have not had a chance to pursue it much more. I have a vertigo issue and get rather disorientated when attempting combat! I had an old Baliev wing to play with and tried quite a few motors, props and batteries. The most success that I had was with a 1250 Kv motor running on 4 cells with an APC 7 x 6 E prop. I tried 8 x 6 as well but it slowed down the turn rate a lot and used more power. The motor I used is a MVVS 2,5/1250 that is basically a .15 (2,5 cc) size motor with a 1250 Kv. It is an IN/OUT runner that has the spinning drum inside a casing. This is really well suited to harsh combat conditions, BUT..........it comes with a high price tag. I had a few from when I was the local MVVS agent and they are gems! You may want to try my motor mounting method which I simply made to fit the existing combat wing engine mount. This protects the motor in a prang quite well, and I think that it could be better shaped to protect the motor even more. Its made from some 1/8" aluminum and simple to make. I hit the deck doing a Fig. 9 into hard ground while flying against a proper combat pilot, and the motor just got dirty and broke the prop. The wing has had its days!

I used 2 x 1300 mAh 2-cell lipo's instead of one 4 cell. It is a bit of a schlepp, but this way I balanced the weight evenly. I stick them into the foam leading edges. I still found the wing to be tail heavy and if you look at the pics, I taped some lead weights around the motor mounts. I've already drawn a plan to make a narrower wing with a higher aspect ratio, but other projects got in the way, and I'm no combat flier anyway. I'm getting a lap time of 3.5 seconds and a 4 minute flight but we are up at 5800 ft. so that helps a bit. I can get the speed to 3.0 secs/lap but then it obviously flies a shorter time. I agree with others that 4 minutes is actually a bit long. Three minutes or even 2.5 minutes would be good for a decent bout. The other thing I tried was to use the Hobby King APC "look-alike" props. They are dirt cheap and more flexible than APC. You do need some more rpm but they work just fine. I do have a video of one of my test flights so I'll try to post it on Youtube.

I used my own KR governor timer (obviously!) and it keeps the speed better in sharp turns than an esc without a governor. I hit the deck a lot if I fly combat and as you all know my system shuts down if the rpm drops suddenly. It does not have to wait for the current to go up suddenly. This saves burning out esc's for sure. These days with much better batteries with lower internal resistance, this is not too bad without a governor.............as you have found out. I would think that the way forward for e-combat is to use no timer at all, and just use a simple 2.4 GHz R/C system with a kill switch for prangs and fly-away's. You can get fairly cheap esc's with heli governor's in them and you don't need to have the motor brake work either. If you try one without and then directly afterwards try with governor, you can feel the difference, so I believe that it is worth it.

I'm building myself a cnc foam cutter right now (well.....trying to!) and then I need to make some simple stunt trainers for our club that has had a lot of interest in C/L since last year. When this is all going, I'll get back to the combat wings. I did in the meantime make an electric Hellcat for some WW 2 combat and that is working very well. I'll post something on that later.

Keith R


* Electric combat 1.jpg (226.22 KB, 786x482 - viewed 10 times.)

* electric combat 2.jpg (246.14 KB, 759x593 - viewed 17 times.)

* electric combat 3.jpg (331.69 KB, 813x589 - viewed 21 times.)
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« Reply #36 on: Yesterday at 11:19:36 PM »

Here is a video of one of the tests with the 8 x 6 prop. I ran it for 1 minute and the lap time on this flight was 3.8 seconds. As you can hear, the wind was pumping but it did not bother the wing much at all. I did fly it against a similar wing with a MVVS .15 glow engine and matched the speed with streamer to the glow model which was the same 3.8 seconds. It was fun while it lasted and the electric wing in my humble opinion did better because the speed was more consistent. That is until I did the figure 9 move! 



Keith R
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