Coronado

My mistake yes I do have the 4s packs. My setup was the turnigy motor 900w,separate ubec,esc,4s 5000mah pack,13X6.5e prop,AR6200 receiver.

I am using an 8 year old futaba 9c with the spektrum conversion. I have received many hits and almost lost a few aircraft.I think ive ignored this for to long. Im wondering if there is something wrong. Also I noticed I didnt have any expo programed in with my flying dream.

I know I had plenty of control serface throw, maybe to much. So im still trying to figure out what went wrong. I dont know if I had to aft of a cg, excess control throws with no expo diled in so it was to twitchy for me to control, or if my old futaba radio with the conversion is bad.

opjose

With your UBEC the AR6200 receiver will see more than adecuate power, so this is unlikely due to any problems with voltage.

Do you have your AR6200 and satelitte module mounted well away from the ESC and other electronics?

It should also be out of the way of pushrods and wires as much as possible.

I normally mount the main receiver low on the plane, and the satellite high and away at a 90 degree angle.

I've never seen any dropouts or signal fades.

I am using either a JR 9503 2.4gHz or a JR 2.4 JR module on a 72mhz JR TX.


I assume that range checks work fine right?

Also have you tried the flight logger? That helps to pinpoint the problem.

-

Yes the plane is twichy, especially with no expo. Dial your expo up ( it's NEGATIVE on Futaba radios for less sensitivity around stick center, and POSITIVE for most other radios... ).... to say -50% for both high and low rates, then make sure that the low rate throws are about half of your high rates.

I found that the plane does not need a lot of throw on the elevator to fly well, but since I'm always afraid of running out of UP elevator on landings I only dialed it down to about 50% of max rates.

-

Also have you checked the motor up/down thrust angle in flight?

I found mine needed even more upthrust.

Throttling up resulted in a pull down of the nose during acceleration, and throttling back ballooned the plane up.

This also makes the plane feel twitchy.

I changed out my washers at the field and I now have it so that there are FOUR washers behind my standoffs on the lower motor posts, one washer on my upper left ( as seen by a pilot ) and none on the upper right ( as seen by the pilot ) this is just about right but gives it considerably more upthrust.

Acceleration no longer causes the nose to pull down, or it does so to an amount I barely notice.

dditch

With my battery and motor, I put the ESC all the way up front under the motor in front of the firewall like Opjose posted. That gave me good CG.
I"ve been flying on low rates or the elevator is too sensitive.

Coronado

Finished the second flying dream. Airplane's cg seems to be at just over 90mm and the manual says 65-70-mm inches aft of the trailing edge. With the esc under the motor and the 4cell 5000mah pack in there it seem to be a bit tail heavy still. Where is your aircrafts cg at? With my receiver and entena where it is maybe thats making it a bit tail heavy. Although I dont believe its that heavy.I have a 13X8e on there right now. What props are you guys running. Does it look ok where I have my receiver and antena? I haven't done any expoxy reinforcement yet and the airplanes flying weight is at 6.30 lbs. Dont know why it came out that heavy. My last one had the same setup and was 5.30lbs I thought flying weight. Maybe my scale is bad. Or is that the correct flying weight.

opjose

I think you are measuring the C.G. from the wrong place...

If I recall it is from the LEADING edge ( I never seen it cited from the trailing edge but I could be wrong... ).

You have an almost identical setup as mine, and I find the C.G. to be very good, though as suggested do dial in a lot of Expo ( 50% ) on the elevator for both low and high rates.

Also make sure that the motor is angled up more than the default or the plane will pull the nose down when you advance the throttle.

I have no washers on the top standoffs and four washers on the bottom standoffs. This is about right.

Re: Weight

No that sounds right.

Take the battery pack out of the plane and hold the plane... it will seem very light for it's size.

The battery adds close to 14oz or so, so you're plane is right where it belongs...

The wing loading is VERY good, and it tends to float in for landings... the hard part is getting it to come down!


Re: Prop

Remember that your 13x8e prop will draw more power than the 12x8e prop I'm using.

With that motor ( I'm running the same thing ) I'm quite happy with a 12x8e prop.

Pick up a 12x8e prop and try flying with that... You can always switch up later if you find you want more thrust ( which I doubt! ).

The 12x8e also keeps the motor cooler... though I always wait 5 minutes between flights to let it cool down.

Nice setup you have there if I do say so... heh...

Coronado

My mistake yes I am measuring from the leading edge. I had a typo. Do you think where my receiver and antenna is located is ok?

opjose

Their placement is fantastic.

Try to straighten the small grey wires as much as you can, without hurting them.

This helps further improve the signal.

The two wires form a 1/4 wave of the 2.4gHz wavelength.

-

I also notice in the photos that the rudder servo is backwards.

It will work the way you have it, but the wires are offset slightly. This will cause more travel in one direction than another.

I'd flip it around to get the servo horn/wheel more in the center of the fuselage.

-

Do you also have the ESC under the motor?

Is there anything else in the rear of the plane adding weight?

The receivers only affect the C.G. minimally so they are not problematic.

Coronado

I flew the plane yesterday for the first time. My cg was around 90mm aft leading edge, yes the esc is directly under the motor. Expo at -70 for futaba. Plane was Identical interms of the twitchyness like the last one. Just crazy tail heavy. I think what I did was put to much expoxy on the stab section while building. I was able to land it, just broke the prop. Found a master airscrew (scimitar profile) prop it is 1360S (3315S). Thats the numbers on it. Is that a 13X6 by chance? Its a much beefier prop than the apc. I need to figure out how to bring the cg forward today and fly it.

Hey how would this motor do? The weight up front would help me out...

http://www.hobbycity.com/hobbyking/s..._650Kv_/_1150w

opjose

That motor will do fine, but because it has a lower KV rating you'll need to go with the suggested prop sizes for that motor. You may not have the necessary clearance for a 14" prop.

I'm still confused as to why you find it pitch sensitive or tail heavy.

I have the same setup as you, and I can roll the plane WITHOUT any pitch change when it goes inverted.

This makes the C.G. spot on for 3D stuff, but it can be perceived as tail heavy by anyone not used to an almost neutral balance point...

Do you have your expo turned up to 50%?

What type of TX do you have? Could it be that you have the Expo reveresed? ( Futaba needs negative Expo while JR and other radios need positive expo to deaden the controls around stick center... )

Also instead of replacing the motor consider doing this.

Tower sells a 2 & 3oz prop weight, which you can install before the prop.

Since this is as far forward as you can get, the effect is more dramatic than adding more weight elsewhere.

Give that a try... it's trivial to install and will pull the C.G. forward.

Coronado

Ill try that.

Also do you know if its ok to reverse the turnigy motor shaft? I broke the part that comes with the motor that bolts on for the prop. And the replacement part is on back order. So I just figured I can losen the set set screws on the motor and reverse the shaft so I can put on a normal prop adapter.

I did notice again that indeed I may have used to much expoxy on the stab section while building. Thus resulting in my cg being off (90mm) instead of the 65-70mm cg the manual calls for. I am stumped as to what else it could posibly be. My expos for my futaba 9c are at -65.

On takeoff and during flight the airplane's tail noticeably drops and just drags along not wanting to fly.

opjose

Re: Prop Adapter

Go here: [link=http://www.maxxprod.com/mpi/mpi-291.html]Click me![/link]

Look for a 5mm Prop Adapter... that's all you need.

Re: Epoxy

There's practically no way that adding epoxy as you did, would throw the C.G. off very far.

Once dry epoxy weights far less than when wet.

I would add the spinner/prop weight to move the C.G. forward.

-

"Dragging" along is NOT necessarily an indication of a tail heavy plane, but may reflect more of an incidence or uptrhust problem.

Have you adjusted the motor upthrust as I indicated?

If so try the prop/spinner weight.

Coronado

Got the plane flying good. Just need a prop sugestion. Ran a 13x6 didnt have much power. What are you running?

Found out I had a bad TX module.

opjose

I initially tried a 6 pitch prop like you have, and found that the plane seemed anemic.

It had PLENTY of "power" ( as yours should and probably does ) but it all manifests as slow speed thrust... like driving a car in low gear.

The plane seemed to accelerate slowly and felt as if it had no power in the air.

I then switched to a seven then eight pitch prop, which is why I've mentioned to you to start out with one of these.

e.g. a 12x8e or a 13x8e.

Start out with a 12x8e prop. If you elect to move up, to a 13x8e prop, test your system with a watt meter before flying.

Put the watt meter in line between the battery and ESC and then with it on, run the throttle up to 100%. After 2 seconds look at the watt meter reading and record/remember it, then throttle off.

What does it report back?

If over 880 watts by a BIT, you should probably stick with the smaller diameter prop, or be careful to use full throttle very sparingly and then not for long.

Coronado

Excellent thanks. Yeah I was disappointed with the power on the 13X6.5e prop I was running. Very poor climb performance.

Also the plane wanted to easily snap roll with minimum elevator movement so im still a bit off on the cg. nI switched to more right/up thrust on the motor as well.

Do you remember off hand how to turn the brake off on this 100A esc I got?

opjose

Turn the plane on and pull the throttle up so the prop spins, then back to idle.

Turn the prop over by hand. If it feels like there is just a very small bit of resistance you are probably OK as is.

If it seems like it will not turn freely, the brake may be on, and it should be disabled.

Which ESC did you use?

Coronado

This is the one I went with

http://www.hobbycity.com/hobbyking/s...idProduct=7341

opjose

Use the 70A ESC programming guide to set the brake...

[link=http://www.suppomodel.com/ESC/escmenu.html]Found here - Click me![/link]

dditch

I broke the plastic stock landing gear a couple weeks ago landing on the clumpy grass before they mowed or rolled the field. I made a pair of aluminum gear using a stick from Home Depot. If I would have been able to find thinner aluminum

I also threw on an MKS292 gyro onto the ailerons, now this will be my windy day plane. I flew this morning in 10-15mph winds. Wind was not all that bad but the ailerons tracked like it was a calm day.

One other mod I did was to put some foam adhesive on the inside of the place where the top hatch pin goes into the front of the fuse. There is side to side play and that rattles in the air. It gets really loud and I worry about something fatiguing. Someone commented and asked how I got the Electric plane to sound like a Nitro. It was the rattling. With the foam, it's quiet again.

I have a 13x8 on it now, I broke my 14x7 prop when I broke the landing gear. I ordered another. Once again, I have a 6S 2650mAh setup and Monster Power 60 motor. The ESC is all the way up front just under the motor and my CG is pretty much perfect per the instructions. A few weeks ago, I noticed that tendancy to roll as I add alot of elevator but w/ the gyro, that's pretty much gone now.

opjose

With that motor you're probably getting alot of torque being transferred back to the airframe.

Does the roll tendancy disappear or lessen if you take the plane high, then back off throttle completely and go straight nose down?

If so, engine torque is doing it.

dditch

I only have it propped for about 800W.
The roll is only when I pull alot of elevator.
Don't recall which direction.

opjose

Next time you have a chance try pulling hard out of a throttle off dive and see if it rolls.

dditch

I did it this morning. It rolled right on me.

Coronado

Guys broke the fuselage on landing a dust devil came in and when it hit the plane kind of cartwheeled. How well do you think thin fiberglass sheeting will hold up on the structural integrity?

opjose

Yup, just put a piece of tape on the outside of the fuselage, to hold things together, then put a sheet or two of fiberglass on the inside and epoxy it...

You'll not even notice the crack once dry.

opjose

Check your control surfaces at their extremes, one control may top out higher than the other.

Also check your wing and elevator alignments.

Also remember that if you have any trims on the plane to prevent a roll when flying normally, this will cause the plane to roll on a power off pitch up.