RE: E-flite J-3 Cub 25 ARF (Full Version)

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lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 1:53:56 AM)

Since I'm planning to put a pilot and some interior later, I didn't glue the canopy. Three little metal sheet screws were enough, the canopy was fitting perfectly. I decided to put two screws on the side and one on the top.




lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 1:58:10 AM)

Here's a look at the battery compartement. I like to put a foam base under the battery. To keep the battery from moving to the back I use a rubber band.




lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 2:02:32 AM)

A look a the interior and the electrical apparatus. With the receiver battery located on this spot, the plane balanced perfectly at 66mm.


Note the red, white and black colors help me plug the charger plug the right way.




lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 2:08:52 AM)

Ailerons were a breeze to put together. Contrary to certain posts in another thread about this airplane I didn't experience any problems with the struts, the holes were perfectly aligned.



lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 2:15:34 AM)

I didn't like to see the ailerons wires through the windows so I used tape to keem them up against the wing and route the wires all the way to the back.




lthibault -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 2:18:09 AM)

There she is standing pretty...this is one sweet little plane.




FlyingGuy -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 12:42:43 PM)

Excellent posts and plane, Luc! What are you using for batteries? I'm finishing up my Cub today.



makiedog -> RE: E-flite J-3 Cub 25 ARF (9/4/2006 1:59:57 PM)

I bought the Cub to primarily fly off the small lake in the back of my house. I've had close to 35 flights on it so far, trying on several different component configurations along the way. The following are some notes and suggestions:

My original eFlite 40 amp esc fried after the first flight when I made a rough landing, splashing lots of water inside thru the holes underneath. So be careful about keeping the ESC dry. I have since replaced it with a CC 45 (waterproofed by CC for $7.50), using it's BEC functions to power the 4 JR servos. Happy to report this combo is a winner, giving me trouble-free flights even in 90 deg. weather. CC's waterproof coating also proved to work great, even after my dunking the plane. Pilot-induced error made it stall, diving while spinning from about 80ft, it hit the water vertically and remain there with the tail pointing up for 10 minutes untill I retrieved it. To my surprise, everything still worked when dried! Only damage were the cowling and one float. This is one tough little bird!

When flying on floats, its important to keep the CG as far forward as possible. Initially I had bundled 2x 3s1p 1800 into an end-to-end configuration (slips in easier). While it flies fine on wheel, it was extremely pitchy when on floats. Reconfiguring the packs to side-by-side solved the problem. I have also left the vertical fin off since I couldn't detect much difference when on floats, it also helps to keep the CG forward.

Flying on floats will definitely chew up more battery since one has to keep the throttle up at 75%-90% most of the time when compared to flying on wheels (50% throttle). with the 3600 (10c) lipo, I'm getting about 11 minutes (use up 80% capacity). With a 4400 (12c) lipo, I'm getting about 14 minutes. All the packs are from 3E Models, more than 50% cheaper than TP.

When making tight turns while taxiing, the water rudder will turn left much easier than right. On take-off, minimize using the rudder to risk tipping. The 12" prop does generate a lot of torque, this is especially pronounced when on wheels. Be very careful not to accelerate too abruptly on take-off. This effect is much less pronounced when on floats.

I have to say this is a very enjoyable float plane to fly, the wonderful scale look and tough built didn't hurt either.



lthibault -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 1:33:41 AM)

Hi,

same setup as Greg, Thunder Power 3S, 4200 MHA 11.1V pack.

I had a second taught about the ESC, decided to swap with my Mini Funtana (Eflight 40 AMP) and put the Phoenix 35 AMP on the smaller plane. Don't wanna take any chance...I'm also using the Expert 4.8V 700 AMP battery to power the servos.

Later I may buy a CC 45 AMP waterproofed ESC, depending on my water take-off experience...I'm inclined to believe that I can avoid water by managing the elevator and keeping the nose of the plane up...we'll see.





Charley -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 2:05:40 AM)

quote:

ORIGINAL: lthibault

Later I may buy a CC 45 AMP waterproofed ESC, depending on my water take-off experience...I'm inclined to believe that I can avoid water by managing the elevator and keeping the nose of the plane up...we'll see.



If I ever had that Cub on floats I'd change the cooling air intake location. Whoever designed that arrangement didn't take float flying into consideration.

CR



lthibault -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 5:07:24 PM)

I'm thinking about a way to make this ESC waterproof. I'd be tempted to put silicon or marine type sealant at every end of the ESC.

Any problem with this operation? Don't think that it would create overheating.




makiedog -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 5:52:33 PM)


quote:

ORIGINAL: lthibault

I'm thinking about a way to make this ESC waterproof. I'd be tempted to put silicon or marine type sealant at every end of the ESC.

Any problem with this operation? Don't think that it would create overheating.




I have tried doing that, it kind of worked in terms of keeping water out. But the problem is water formed by condensation cannot escape, unless you have a way to create a vacuum.

For those who think the interior of the Cub will never get wet, trust me, it will, no matter how good a pilot you are. I have even coated the wood interior (front portion of fuselage) with a thin layer of epoxy to waterproof it.



Charley -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 6:12:59 PM)

quote:

ORIGINAL: lthibault

I'm thinking about a way to make this ESC waterproof. I'd be tempted to put silicon or marine type sealant at every end of the ESC.

Any problem with this operation? Don't think that it would create overheating.




I hope you aren't thinking of silicone rubber cement. The solvents in that stuff are corrosive. I wonder if the silicone sprays intended to waterproof auto ignition components would work.

CR



FlyingGuy -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 6:14:59 PM)

Hi Gents, Anyone have any take-off, flying, landing tips for the Cub? I made my first takeoff today and she rotated left and I broke a prop. No damage to the bird but now I am more apprehensive than ever and put her back in the truck. My experience thus far is about a year w/ HZ Freedom, PZ Cub, PZ P-51, Cox Spitfire, and my E-Starter on floats. I'm also confused about setting up rates and expo and control deflections with my Futaba 7C .. that may or may not be related to today's event. Thx, Harry



lthibault -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 6:27:09 PM)

FlyingGuy,

many possibilities here...did you perform a premature take-off, i.e. the plane stalled, you raised the aileron on the side of the stall, making things worse?

With tail traggers make a slow start until the tail is up, then gradually accelerate until the plane gain speed and you will be almost airborn, just a touch of up elevator. This is gained through experience and feelings. It is like the plane is already flying on the ground.

I fly another tail dragger, a warbird (P40 Warhawk by Hangar 9) and it is the same technique.


As far as the exponential goes, it is just a way to ''slow down'' or increase the servo's response to the stick, thus helping you better manage the plane. Try to fly ''scale'', i.e. decrease the response by 20% (according to the J3 Manual). You can fine tune this before doing an actual flight, just spend a little bit of time in your shop. Put the receiver of the plane on and try your radio, change the exponential and hit the switch while you move the sticks, you'll be able to see the difference by looking at the rudder, elevator or ailerons.



Charley -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 6:42:59 PM)

quote:

ORIGINAL: makiedog

I have tried doing that, it kind of worked in terms of keeping water out. But the problem is water formed by condensation cannot escape, unless you have a way to create a vacuum.

For those who think the interior of the Cub will never get wet, trust me, it will, no matter how good a pilot you are. I have even coated the wood interior (front portion of fuselage) with a thin layer of epoxy to waterproof it.



I downloaded the manual to get a look at the fuse construction. I think I'd put the ESC on top of the battery compartment, open up a couple more holes on top of the firewall and open up the front of the cowl just below the prop shaft for cooling air. And, as you said, coat the wood with thinned epoxy.

I'd make a scoop to go on the hatch and extend it forward of the holes. That should improve air flow and keep some water out. Have to be careful to see what it does to the aerodynamics. Make a rearward facing scoop for the cooling air exhaust, maybe open up that hole too.

CR




lthibault -> RE: E-flite J-3 Cub 25 ARF (9/5/2006 11:59:37 PM)

Hmmm...I've been thinking about this problem. Here's my concept:

While some folks in similar thread have mentioned that they decided to shut off the holes completely and didn't report any problems so far, I would not go that extreme. About using some kind of a fabric that would keep the water out but allow some air flow? I'd be interested to try this.

So I could use this mask filter and put it under the trap (see photos).

I don't like to mess with epoxy so I'm going to use yellow acrylic paint to protect the wood.





Greg Covey -> RE: E-flite J-3 Cub 25 ARF (9/9/2006 6:57:55 PM)

We finally tested the J3 Cub 25 on water and it performed very well. The high power level of the E-flite 25 outrunner motor and the very rigid design of the float cage allows you to take-off and land even in small areas. The video was taken on a single charge of the ThunderPower 3s2p 4200mAh Lithium pack option. Even with the flying part mostly cut out of the video, we only used 60% of the pack as displayed on the Cellpro 4s Balancing Charger.

I simply covered the bottom holes with masking tape on the inside and removed it when we were finished flying. Some water does splash up on the bottom of the fuselage but probably not enough to cause a problem.

J3 Cub 25 Video 3 (12meg)



lthibault -> RE: E-flite J-3 Cub 25 ARF (9/10/2006 1:55:59 AM)

That's great news! Looking at the video I'm pretty sure that I can use the airplane at the location I was planning, it is a small lake but will have plenty enough space.

To protect the fuselage Instead of masking tape I will use some fabric that my daughters use for arts projects. It will allow enough air flow and I found some that was colored yellow so the look will be OK. Will cut the piece to cover just enough space on top of the 4 holes.

What about the CG? Did you have to make any adjustments at all?



Greg Covey -> RE: E-flite J-3 Cub 25 ARF (9/10/2006 2:21:03 PM)

Luc,

No adjustments were made to the CG and it was flying slightly tail-heavy...which is just how we like it for slower landings.



Charley -> RE: E-flite J-3 Cub 25 ARF (9/11/2006 3:19:15 AM)

quote:

ORIGINAL: Greg Covey

Luc,

No adjustments were made to the CG and it was flying slightly tail-heavy...which is just how we like it for slower landings.



Some nice flying there, congrats.

Obviously the model is very "wet" when the R's are brought up, so the bottom of the fuse needs to be covered, as you did. Lots of spray there.

It's also obvious that the incidence between the floats and wing need to be adjusted. When I saw your video of the TO from grass, I noted that the pilot had to yank it off before it ran out of runway. I figured that the model's wing might have a bit more positive AoA
when it was taking off from water. Nope, same zero AoA. You guys need to put spacers in the front of the float mounts.

My friend brought his over so we could balance it and photograph it, maiden yet to come.

Other than those suggestions, pretty little model, Guys!!

CR








lthibault -> RE: E-flite J-3 Cub 25 ARF (9/11/2006 9:18:18 PM)

Although I've been successfully flying warbirds and 3-D airplanes, I just realized that a Cub was a total different beast...

Gave it a try on wheels yesterday. On the runway the plane would always turn in one direction or another, finally tried to take-off but premature...too much up elevator, snapped and landed on the nose. To my total surprise nothing was broken except the prop. Also found an incorrect setting on my radio: exponential on the rudder was supposed to be -20% and it was +20%!

Will try to fly the tail and raise it earlier while slowly increasing throttle. Mind you we have an asphalt runway and that is not helping either.





FlyingGuy -> RE: E-flite J-3 Cub 25 ARF (9/11/2006 10:39:21 PM)

So... is the concensus that the expos are to be set to the negative values, -10% and -20%?



FlyingGuy -> RE: E-flite J-3 Cub 25 ARF (9/11/2006 10:45:54 PM)

Had my second flyimg session with the Cub this morning, she's a beauty but a handful for me (someone just graduating from the smaller park flyer world). Again, she has a tendency to track and depart to the left ... even tho I am adding R rudder on takeoff, and then she has a tendency to want to roll L in flight as well. The control surfaces don't seem to have any L bias in them so I'm a bit confused (understatement). I'm happy to say that the stock setup has the power to pull out of the takeoff problem (as I create it), but it makes for some hairy takeoffs!



Greg Covey -> RE: E-flite J-3 Cub 25 ARF (9/12/2006 1:29:24 PM)

The use of exponential is purely an individual taste. It simply softens the stick center to your preference. Whether it is positive or negative depends upon it being a JR or Futaba radio, respectively.

Keep practicing take-offs with your Cub and it will become easier. Based upon your brief description of events, you may want to check where the control surfaces reside when you think it is trimmed for level flight. It is a common mistake to offset a rudder deflection with aileron or visa versa.

Good luck!



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