russwyte

Hello ferro heads.

I bought 2 hanger 9 cubs a few years back. One I built with a saito 65 4 stroke engine, and the other I had been saving until I could find an electric package which was attractive to me. Well that time has come.

I saw the AXI 4120-18, and thought that it fit the bill perfectly for my 80" span (850 sq in) cub.

I ordered the motor and the 70 amp Jeti opto isolated ESC along with the radial motor mount for that motor. I also order an ultimate BEC for the receiver power.

I am going to use 18 cells in two series wired nine cell packs.

All in all I expect the weight to be about 8 to 8-1/2 lbs.

Everything is going together great, and I am very happy with all of it so far, but I have a couple of questions.

1) What prop would work best? I ran some mototcalc numbers and thought that it should fly great with 14x8 and 14x10 props, but since this is my first electric I thought I would ask if anyone else has run a combo like mine with a similar prop. The ModelMotors site shows a 13x11 prop for that combo, but I like to go with larger props on a plane like the cub especially because scale appearance is important to me.

2) How do I route the wires and connector from the battery to the ESC in such a way that I do not have to take everything apart to unplug the battery and charge it at the field. Are there any cool ways to do this that don't look too sloppy?

3) Should I install a power sitch either between the battery and the ESC or possibly between the UBEC and the reciever?

If these are incredible newbish questions which are answered in detail someplace I would appreciate a kind pointer to some good howtos and tips.

Thanks,
Russ

Greg Covey

Hi Russ,

A 14x8 prop should work great. You'll have good take-off power and can throttle back to half stick when in the air.

Wire your setup as shown in the photo. Use a "Y" adapter to connect your two packs in series and then to the ESC.

The On/Off enable switch goes between the UBEC output and the receiver. Note that the UBEC output can connect to any spare channel on the receiver and the ESC control line must connect to the throttle channel.

Good luck!

russwyte

Greg,

Thanks for the pointers!

How do you handle charging at the field? Could I just wire an additional connector in parralel with the wires going to the ESC and then leave that charging connector exposed? Is there some kind of cool flush mounted charging recepticle? I am using deans ultra plugs.

Thanks,
Russ

Greg Covey

Russ,

You've touched upon one area of glow-to-electric conversions still in it's infancy. You can't just parallel a charging connector because you need to disconnect the ESC when charging. On some models, I have easy hatch access to the Dean's connection and pull it apart to re-charge. On others, it is sealed inside.

One modification I did to several of my glow conversions was to add a MaxCim Charging Harness to allow me to re-charge while keeping the wing on and the batteries installed. I have found this feature to be invaluable for full day events. You can set up your planes in the morning and keep flying or recharging all day. You simply taxi into the pits and plug in your charger after a cooling period.

So far, only MaxCim Motors seems to offer this convienience. SR Batteries also sells the PowerPole-style fuseholders but not as a complete assembly for charging.

These pictures show my modified MaxCim Charging Harness for using Dean's Ultra connectors. I simply plug the harness in between my controller and battery. The 40amp ATO-style fuse can be moved from a "RUN" position to a "CHARGE" position that disconnects the controller while charging.

Plug-n-play! Yeah, that's what I like.

Greg Covey

Here is another look at a charging harness on my Hangar 9 Corsair e-conversion.

Once again, I modified a MaxCim Charging Harness to use Dean's Ultra connectors, a 40-amp ATO-style fuse, and a single battery connection. My hope is that someday this type of charging harness will be sold to R/Cers for easy recharging of the battery packs in the plane. The ATO fuse moves from the 'Operate' to the 'Charge' position to connect the charge jack and disconnect the battery from the controller. This assembly allows me to mount my wing once in the morning of an R/C event and simply taxi into the pits for a recharge after a proper cooling period. It is a true convenience.

russwyte

Greg,

Wow!!! Thanks for so much help.

That looks like a great way to set it up. Do you have a link for the MaxCim harness?

You have been very helpful, I have have learned a lot today.

Thanks,
Russ

Matt Kirsch

My Feedback: (21)

Where'd you find the 40 Amp fuses? The largest ATO type of fuses I can find at parts stores are 25 or 30 Ampers.

russwyte

I was thinking about a SPDT switch wired so the the battery and the charge rececpticle shared a common pole and one throw created a circuit to the charge connector and the other to the ESC.

The highest rated SPDT rocker switch I can find is 20A. But that would probably be ok wouldn't it?

I could do that for less then $5.

Greg Covey

Russ,

Here is the link to the [link=http://www.maxcim.com/]MaxCim Motors[/link] site. Go into the "Ordering Information" section for pricing. Prepare yourself first because they are not cheap!

You'll have to find the DC voltage and current ratings of the switch because you'll be running 40amps at 22volts through it.

Matt,

Many places sell them on-line. [link=http://www.midwayautosupply.com/detailedproductdescription.asp?4570]Midway Auto Supply[/link] is one of them. Locally, you may have to go to a boating center or rural auto parts store.

russwyte

It's flying!

I will post some pics later when I get a chance to pull them off the camera, but construction was very straight forward. I mounted my motor controller so that it mostly protrudes into the cowl, and that allows for excellent cooling. This was accomplish by spending a few moments with the dremel making a hole in the firewall. I also made a few more holes to allow cooling air into the cabin.

Here is the run down for my setup:

AXI 4120-18 motor with radial mount

JETI 70 amp opto isolated ESC

18 GP 3300 NiMH cells in two 9 cell packs.

Ultimate BEC

Hitec QPCM receiver

All up weight is a shade over 8 pounds.

I have tried two props so far.

14 x 9.5 APC electric thin (very good but very fast)

15 x 8 APC electric standard (even better, but still way to fast)

Motor thrust is over 100 oz, way more then a cub really needs, but very reassuring to have that "get out of trouble" power.

Make sure you use the hard timing setting on the JETI controller and deactivate the brake. Power seemed mch better with hard timing enabled.

I was very nervous about the first flight since it had been about 8 years since I had flown a power plane or anything with a wing loading of more the 15oz per Sq. foot. I have been flying sailplanes exclusively for that period of time (mostly RES, but some full house). I got tired of cleaning slime off of my glow planes, so I simply got rid of them. I got the itch to do some power stuff again, thus this project. I am totally sold on electrics, and I honestly don't see myself building an internal combustion powered plane ever again.

Since I was a little shakey at the prospect of flying my new beauty myself after so much time allowing rust to gather on my left thumb (You don't have to do much throttle work with sailplanes) and I just didn't trust myself to be the test pilot. So I trusted my cub to "Bo" I am not sure his last name, but I was told by everyone at the field that he could fly any ship, and from what I saw him doing with his bird I knew it was true. Well, Bo agreed to test fly my bird, and after our pre flight we tested the motor and he was amazed at the pull this cub had.

There was a pretty good crosswind (5-10 MPH) and Bo elected to take off across the runway. I was a little worried about that, since the runway is just about 50 feet wide. But, I trusted his instinct. As it turned out my fear was baseless. The cub lept of the runway with only a very short roll, maybe 15-20 feet and proceeded to climb like a rocket. Bo laughed and said, "Well she has plenty of power! I was really expecting sluggish performance when you told me it was electric." Bo flew the plane in slow flight, and power off and power on stalls, and confirmed that it behaved excactly as it should. He did one half turn spin after a power on stall and said I was not off the hook. I would have to fly soon. Well after he confirmed that the control throws were sane and the plane seemed well balanced and behaved I took over the controls. My smile was from ear to ear. Wow! The plane was very realistic at about 1/3 throttle and was way faster than scale at 3/4. At 100% you could pull 60 to 70 degrees, no problem. I was still a little shakey and honestly flew pretty badly, but in control, this is a very forgiving ship. I was completeing the 7-8 minute flight with what was shaping up to be a decent wheel landing when I pulled the ever embarrassing -nose over at the end- trick. No damage done to the plane, just my ego. Lesson learned. Keep that elevator up on roll-out!!!

Sunday I flew again this time fully solo, I made one small change to my setup by adding about 3 degrees of down thrust to make the ship less pitchy with throttle. The wind was not being kind again today, if anything it was stronger, so I decided that while I would take off on the tarmac, I would land on the grass since it is well kept, and I could land directly into the wind. Well this flight was much better. I did a couple of nice large loops from level flight, one very lazy roll, and several low and slow passes. I may try a slightly finer pitch on the prop since mid throttle setting seem just too fast. A cub just should fly that fast at half throttle! I will shoot some video next time out.

Well thanks to all who contributed to the success. Especially to Greg whose AXI projects were a large part of my inspiration.

Cheers!
Russ white

russwyte

Pics:

Pleas ignore the messy shop.

I will post some flight pics and a link to flight video when I get a chance.

Greg Covey

Russ,

It looks like you're having fun with the Cub conversion.

Thanks for posting some pictures.

It seems that you have good power with your setup. You can probably see now in hindsight that perhaps the 4120-14 on only 14-cells would still likely be sufficient power and drop your flying weight by 1/2 pound.

Try to test your CG by moving it back 1/4" after a few flights. This should help slow you down when cruising around and landing. I suspect that you are a little nose heavy yet.

Good luck!

russwyte

Update:

Greg: I think you may have misunderstood me a little. The cub will slow down very well, but it only flies slow at about 1/4 to 1/3 throttle. Which feels a little wierd. I solved this by going to a 15x6 prop which is fantastic! Take-off roll is even shorter now, and climb is improved. 1/2 throttle looks and sound very satisfying in the air. 100% throttle throws this pup around with authority. From horizontal it will pull vertical for proabably 250 feet, then does nice hammerhead stalls.

I also tried 15 cells with a 16x8 prop and REALLY like that combo. It has just slightly less top end, but sounds very realistic. The only "problem" - if you want to call it that is that - is that I like the extra weight of the 18 cell package. Cubs like to float in ground effect a lot, and with 18cells it settles a little quicker. But I was very excited to see that performance was still much better than it was with a Saito .65 4 stroke even on 15 cells. On 18 cells its not even close. My soaring friends are now trying to talk me into setting up the cub for glider towing. I really don't think I will, but I am considering getting the Hanger9 super cub for just such a purpose, for that I will get the 4130 motor. I would like to have flaps

gyronuts

Hi,
I was also considering a hanger 9 conversion but procurred a Thunder Tiger 84" artf cub. Very similar to hanger 9 one. Fitted with a Maxim, 3:1 superbox and a 14 x 10 APCE prop on 17 x 4/5 Pansonic 2000 NIMH cells. Flies well. Bill