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E-flite J-3 Cub 25 ARF

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Old 10-11-2006, 07:48 AM
  #226
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Default RE: E-flite J-3 Cub 25 ARF

OK gents, I am running the eflite ESC in my Cub and yesterday the ESC must have overheated because the Cub lost power to motor and control surfaces and crashed. I was close to the ground on approach when it happened and the crash opened a 1" gash in the leading edge and bent a wing tip. There was no prior indication of a problem. Air temp was 55 deg F and she had been flying about 5 minutes, mostly at 60% - 75% throttle... I did not think that I would be taxing the system in those conditions. I was also flying on a single 3S 2100 LiPo, which was situated close to the ESC in the battery space. That may have contributed to the crash as well. So it's time to upgrade to another ESC and fix the damage. Anyone have any hints on how to apply ultracote covering to the curved tip? I was going to replace the wing but given my skill level, I'll fix her and keep on banging it up and build another one when I've mastered her. Onward, or should I say, upward!
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Old 10-11-2006, 09:05 AM
  #227
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Default RE: E-flite J-3 Cub 25 ARF

Quote:
ORIGINAL: FlyingGuy

OK gents, I am running the eflite ESC in my Cub and yesterday the ESC must have overheated because the Cub lost power to motor and control surfaces and crashed. I was close to the ground on approach when it happened and the crash opened a 1" gash in the leading edge and bent a wing tip. There was no prior indication of a problem. Air temp was 55 deg F and she had been flying about 5 minutes, mostly at 60% - 75% throttle... I did not think that I would be taxing the system in those conditions. I was also flying on a single 3S 2100 LiPo, which was situated close to the ESC in the battery space. That may have contributed to the crash as well. So it's time to upgrade to another ESC and fix the damage. Anyone have any hints on how to apply ultracote covering to the curved tip? I was going to replace the wing but given my skill level, I'll fix her and keep on banging it up and build another one when I've mastered her. Onward, or should I say, upward!
When that happened to me (different model, same event), I immediately closed the throttle and the controls started working again. It appears that the battery may recover a bit when the motor load is removed. It's worth a try.

To get any film covering to mold to curved surfaces you get it hot enough to stretch and pull it down on the edges.

CR
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Old 10-12-2006, 10:09 PM
  #228
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Default RE: E-flite J-3 Cub 25 ARF

FlyingGuy,
Which E-Flite ESC were you running? the 40amp or a smaller one?
I run the GP Silver Series 45amp ESC on mine .. ive never had a heat issue and I like you run a single 2100mAh Lipo that sits right next to the ESC the battery in mine is only slightly warm to the touch after a 8 to 10 minute flight and the ESC is cold. I run the E-Flite Power 25 motor with a APC 11x7E prop and it only pulls 28amps at wot and i normally fly around at 1/3 to 1/2 throttle so i'm by no means over taxing the 45amp ESC
Ive come to the conclusion that the Power25 is a bit over-kill on this aircraft but im not complaining just stating an observation. Extra power is always good unless it rips the nose off the plane

I do find the E-Flite J-3 Cub 25 a very fun plane to fly. It does the most beautiful hammer head stalls. I can't get my Mini Funtana to do them anywhere near as good as the cub its just a delight to fly. Although I did have to get use to its take-off characteristics er well its more of the bad habits ive picked up flying over powered sport type planes that only take 5 feet ( or less ) of roll-out to get airborne. So a plane that requires a more gentle roll out and lift off is kinda new to me , It's also rather challenging on my rough gravel road/runway but ive begun to master it!..
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Old 10-21-2006, 01:29 PM
  #229
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Default RE: E-flite J-3 Cub 25 ARF

So what have you all done about those long ugly screws used to mount the horns on the ailerons? Looks like they would have tried to dress that up some. Aren't those things about 20mm or so?

Finally gave up on the nylon wire keepers provided, and just used Z bends, much easier and less stress on me and the hardware, especially when I decided to pick a Z bender tool.


And Tall Texan, if you are still around, where do you fly up there at Republic? I'm north of Deerpark, about 25 miles north of Spokane, HWY 395.
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Old 10-23-2006, 06:11 AM
  #230
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Default RE: E-flite J-3 Cub 25 ARF

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ORIGINAL: xrossbow

So what have you all done about those long ugly screws used to mount the horns on the ailerons? Looks like they would have tried to dress that up some. Aren't those things about 20mm or so?
I used the Dremel cutting disk to cut the screw flush to the horns.
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Old 10-23-2006, 10:39 AM
  #231
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Default RE: E-flite J-3 Cub 25 ARF

Thanks Luc. I had been thinking about the Dremel, but kept having nightmares about it slipping and taking off down the wing. :-)

Had to go to town anyway, so picked up some heavier side cutters. Those worked fine and then I worked them down a little more with the Dremel.

I have a little bit of alignment problem on the horizontal between the wing and horizontal stablilizer right now, so trying to work out the best solution on it. The horizontal stab is slightly higher on one side and then the situation is aggravated a little more with the wing.

Finding enough time to stay with it is the big problem. Winter coming and trying ot get everything ready for it. Wonder why I didn't do all these things during the summer.
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Old 10-30-2006, 08:28 PM
  #232
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Default RE: E-flite J-3 Cub 25 ARF

Xrossbow,

I live right on Lake Curlew. We have a house on a point so that is where I fly. Otherwise, I fly at the Republic airport which is about 2 mi from me. Haven't been on this fourm much latley as I am now building the TopFlite Beech Staggerwing.
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Old 11-01-2006, 10:49 PM
  #233
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Default RE: E-flite J-3 Cub 25 ARF

just a few questions please, I am ordering a 6 ch radio that is being sent with futaba 3110's. They say they are rated at 22 oz. Will this be enough for the cub? If not what would be good? One more thing, the thunder power lipo that is recommended with the kit is rated at much more than 40A. How is this not frying the esc. I will prob run 2 2200 lipos together just dont want to pay for the 40A if I need something bigger, gonna run the power 25. Not planning on the floats for right now but you never know....
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Old 11-02-2006, 05:46 AM
  #234
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Default RE: E-flite J-3 Cub 25 ARF

The servos may be a little on the light side for the Cub. I run Hitec 81's in mine, 36 oz of power. As for the battery, 40 amps is it's max out put, the most it can put out with out damage to the pack. No concern with the esc, it will only pull what it's rated for, if the motor demands more the esc is going to shut down. The two 2200 paralleled should work out ok. The 2 packs paralleled even if they are only 10c rated is going to give you 44 amps of available power.

EDIT: Just thought of something, you didn't mention what size esc you are using. If it's rated higher then the packs capabilities then yes you could run into a situation where due to set up problem or motor problem you could over tax the pack.
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Old 11-02-2006, 06:47 AM
  #235
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Default RE: E-flite J-3 Cub 25 ARF

UPDATE: Something to look out for. Mine met the ground a lot harder then planned last night. Rear strut on the landing gear decided to let go. Post landing inspection showed it was just barely connected to the main strut, really poor solder/braze job. Results: Tire rotated backwards, broken wing strut, broken prop, boogered up cowling and spaghetti landing gear. [:@]
Might want to look at yours, I'm going to rebraze my new ones just to be sure.
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Old 11-02-2006, 11:28 AM
  #236
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Default RE: E-flite J-3 Cub 25 ARF

Thanks for the info, ordering the 81 metal gears now. I have ordered the power 25 and the e-flight 40a esc with the 12x6 prop. Gonna re solder the landing gear also now. Thanks for the tip as Im sure I will have some harder than wanted landings
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Old 11-03-2006, 06:55 AM
  #237
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Default RE: E-flite J-3 Cub 25 ARF

Crazy 8,
Just remember the warnings on the esc!!!!!!!!!!!!!!!!! They don't like to get hot.
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Old 11-11-2006, 10:45 PM
  #238
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Default RE: E-flite J-3 Cub 25 ARF

Ready for Maiden Flight

But awfully windy, so another day.

Finally got the J3 ready. Added some of the mods discussed in the thread.

Paul and Luc, I added the bungee struts, but slightly different in securing the strut wires under the fuse. Shaped some plastic pieces to the same size as the landing gear nylon straps, left a slot between them for the bungee strut wires.

Customized the front of the cowl area for cooling. Raided the wife’s sewing room for some small pins to add around the center air hole to sim bolts.

A little pin striping for door area.

Props……………… currently have the recommended 12x6. Any reason to drop down to a 11x7 or 10x6. Current draw seems to be in ok range during a bench test with the 12x6.
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Old 11-11-2006, 10:51 PM
  #239
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Default RE: E-flite J-3 Cub 25 ARF

Tall Texan

That's a pretty area up there. I go that route once in while on my way to Okanogan to visit folks.

What do you have for hobby stores up that way? Many fliers in the area?
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Old 11-13-2006, 10:42 PM
  #240
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Default RE: E-flite J-3 Cub 25 ARF

Hi,

Update: Had to order a new cowling and front windshield, broke a couple of props. Reinforced the wing area where the screws meet the blindnuts. Structure is very fragile and will brake if one of the wing tips hit the ground.

I must say: I own quite a few airplanes, both electric and gas, many warbirds. This one is a real challenge for take-off.

As I had a day off today I went to the club and used a single 4200 MHA Lipo to practice take-off. It is an asphalt runway.

Finally got the plane airborned after about 7-8 trials. With the second Lipo, I tried a more agressive approach, i.e. adding power while I was slowly releasing the elevator...looked like it was ok but suddenly snapped to the right and went nose down in the mud.

I'm beginning to be suspicious about the fact that you can't find any ground take-off video of this product [>:].

Or should I put on the floats and use it mainly on water?

- An RC pilot who's starting to become frustrated with this J3-Cub lesson...
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Old 11-16-2006, 08:58 AM
  #241
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Default RE: E-flite J-3 Cub 25 ARF

Having flown this thing both on land and water, I agree, its much more tricky to take off on land, probably due to the short tail. It is much more managable if power is applied very gradually, as well as holding some right rudder (using exponential helps). Otherwise, it will snap to the left. On water, it is much easier, since the floats keeps it fairly straight. I find no difference in flight characteristics when the plane is flown with the extra vertical tail fin, therefore I leave it off- helps keep the CG forward.

I do have an issue with the covering, which seems to wrinkle up every so often, requiring me to use a heat gun to keep it taut. Anyone has this problem?
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Old 11-16-2006, 01:24 PM
  #242
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Default RE: E-flite J-3 Cub 25 ARF

Makiedog,

thanks for the info, you're confirming my assumptions. I'm also suspecting that the short tail is a major factor for those habits.

I don't really mind because the first reason to choose this product was to add a seaplane to my collection. So far my plan was to practice as much as possible on ground before moving on but I find it useless to persevere and run the risk of other snaps and crashes. Will then put on the floats and use it mainly at the lake.

Concerning covering, I didn't really notice that but I'm used to fixing up covering on my planes with the heat gun / iron.

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Old 11-17-2006, 01:29 AM
  #243
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Default RE: E-flite J-3 Cub 25 ARF

Relax the elevator as soon as the tail begins to fly, slowly, smoothly building speed until you reach flying speed. Stay on the rudder. Cubs fly much better when you use the rudder. Especially when taking off. Cubs require good tail dragger skills.
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Old 11-18-2006, 12:05 AM
  #244
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Default RE: E-flite J-3 Cub 25 ARF

Gents,

My cub has now ended his land-based activities and is beeing permanently converted to a seaplane.

Some of you folks starting to build this kit or having to replace the cowling may appreciate this technique. By simply drilling two holes at the location shown on the photos, adding blind nuts with a tiny bit of epoxy to fix them good, I was able to use only two screws to hold the cowling and it is very strong and solid.

Also decide to use yellow tissue to protect ESC and electronics from water. Still allows some air to flow.



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Old 11-23-2006, 02:23 AM
  #245
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Default RE: E-flite J-3 Cub 25 ARF

Finally choose another way to isolate the battery compartment. Used covering on the hatch, added a screw and voila.

Also used covering to hide the landing gear slot. This little buddy will be on floats for the rest of his career.

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Old 11-23-2006, 03:50 AM
  #246
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Default RE: E-flite J-3 Cub 25 ARF

Luc, nice job on her. Question though. Don't you think that's a little hard on the motor shaft and mount hanging that way? I suspend mine off the wings, as they were designed to hold her weight.
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Old 11-23-2006, 12:41 PM
  #247
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Default RE: E-flite J-3 Cub 25 ARF

Good point. I use bungee cords as you can see and beeing gentle when I handle it, I don't fear any problem, never had any so far. The mount and motor shafts are very solid.

I see that you also have the E-flite P47 in your collection. One sweet little plane!

You might like to see my mods (battery hatch, landing gear reinforcement and steerable tailwheel):

[link]http://www.rcuniverse.com/forum/fb.asp?m=4687260[/link]

http://www.rcuniverse.com/forum/fb.asp?m=4753813
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Old 11-24-2006, 06:21 AM
  #248
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Default RE: E-flite J-3 Cub 25 ARF

Cool thanks Luc, the Jug is a sweet flying bird, no evil tendencies like the Mustang.
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Old 11-24-2006, 06:02 PM
  #249
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Default RE: E-flite J-3 Cub 25 ARF

You bet!

That's why I'm not interested for any Mustang RC airplanes below the .60 size.

Tried many of them, especially the Alfa products (styrofoam crap); they're just too flimsy and sensible.

I'm actually planning to maiden my World Models P-51 Petie 2nd .60 plane tomorrow morning. This is a glow to electric conversion project. You can see it on another thread:

[link]http://www.rcuniverse.com/forum/fb.asp?m=4908272[/link]
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Old 12-01-2006, 08:03 AM
  #250
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Default RE: E-flite J-3 Cub 25 ARF

Hello everybody,

I'am new here. Excuse my english, i write from french-part of switzerland. I ordered yesterday a J-3 from e-flite at my local dealer. I almost can't wait building and flying this wonderfull plane. As my car is not so hudge I will be forced to
unmont the wing and the struts for transportation.
My questions to you all J-3 gurus:
- will the unmont of the wing and struts be a problem ?
- How long will it take till the screw won't bite anymore in the wood ?
- Do the struts have any functionality in the J-3 or are they only a kind of scale good looking finish ?

Thank you for your answers and good flying

Lambertino
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