My H9 Piper J3 Cub Conversion - RC Groups
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Jul 25, 2006, 07:17 PM
Rather be Hover'n
Redbeardrc's Avatar
Discussion

My H9 Piper J3 Cub Conversion


Hi everyone.

My first plane... my first conversion.....

Hangar 9 - Piper J-3 Cub 40
E-flite Power 60 Outrunner
Phoenix 80 Controller
TP 6s2p 4200 Prolite Lipoly
APC 15 x 8E
Hitec Supreme 8 Reciever
Futaba 1500ma NiCAD Flght Pack

Hoping to maiden this week.
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Jul 26, 2006, 08:51 AM
jrb
jrb
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Very nicely done!

Here’s a shot of my H9 .40 Cub (80”); it the previous rev, been flying it for almost 5years.

Have had several motors under the cowl, and currently am flying it on the AXI equivalent or the E-Flight Power 60 – 4130/16 w/Kv=390 vs. the 400 of the 60.

Also use a 15x10E; a brown permanent marker can make it look more like a wood prop – don’t even try a wood Zinger – major waste of money.

But On closer to 5S versus you 6, and I’m flying with 16xIB4200 Zapped & Pasted NiMh.

I pull about 30amps at WOT and am off the ground before 50%!

Folks at the filed surprised to see my Electric Cub so well; specifically inverted for the full length of the field, as well as very non-Cubish rolls and loops.

Though, I really like to fly it Cubish, especially doing scale like approaches and low speed fly bys.


Couldn’t get my other combos ( https://www.rcgroups.com/forums/show...84&postcount=5 ) to slow down (rpm) enough, and didn’t like flipping from off to on as seemed to be a good way to blow a spur gear.


Do you have a 5S pack? You could use the 6S and another 60 in any of the H9 .60 warbirds.


BOL,


Jim

PS: I upgraded to the Robart landing gear (1/5th), make a huge difference; also like flying with skis in the winter.
Jul 26, 2006, 05:35 PM
Rather be Hover'n
Redbeardrc's Avatar
Thanks jrb. The landing gear looks interesting, I'll have to look them up.
Jul 27, 2006, 12:17 AM
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rc-eflyer's Avatar
It should have plenty of power for sure!!!! I just maidened mine this weekend with an EFlite 46 on 3S2P 4200 TP prolites on a 16X12 prop and it took off and climbed nicely on 1/2 throttle. It did loops, stall turns, spins, and flew it inverted and never needed more than 3/4 throttle .
Yours looks very nice BTW. One thing I did that you might want to consider is cutting out the "eyebrow" scoops to get more cooling to the motor. Also, did you say this is your first airplane?? If so I hope you have some help on that maiden. Taildraggers are a little tricky . Good Luck and let us know how it goes. I'm thrilled with mine

Steve
Jul 27, 2006, 01:18 PM
Rather be Hover'n
Redbeardrc's Avatar

Maidened Last Night


Thanks Steve. The "eyebrow" scoops are cut out. One sends cool air over the engine and heatsink mount and then out the bottom. Additionally the motor has fan blades on the front that push a lot of air thru the inside of the motor. The other eyebrow is ducted to bring cool air into the body of the plane to cool the speed controller and battery. That air exits out the rear bottom near the tail.

Yes, my first plane. I had a friend who's an great pilot maiden it for me last night. I flew it a little while it was high in the sky, but I let him handle the rest.

By the way it was 100 degs F last night and the battery was cold and the motor and speed controller where hot but not untouchable, so I don't think there's any cooling issues.

The maiden went well. She had plenty of power, enough to hang from the prop in the 100 degree heat for about 5 seconds or so! Loops, rolls, stalls, etc. were no problem for her. She also flew well at Cub levels. The only problem I have is she's either not balanced well or doesn't have enough down force. I moved the battery back and the motor down and to the right which helped a lot, but there's still some tweeking to do.

The most important thing is she's home resting and in one piece!
Jul 27, 2006, 05:23 PM
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rc-eflyer's Avatar
Congratulations on the maiden . I see now (after reviewing your pictures) how nice a job you did on routing the air flow . I left the smaller window on the port side out for an air exit and also to insert and remove the battery pack without taking the top hatch off.
I'm really tempted to buy one of the Robart functional landing gears for mine. Did you notice the tendency to want to bounce on landing? I think that would solve it and look great too. Pretty pricey though!!!
I'm going to also invest in one of the Eagletreesystems data loggers and do some experimenting with different props in the near future.

Steve
Jul 27, 2006, 05:53 PM
Registered User
JRB,
Why didn't you like the Zinger prop??
Jul 28, 2006, 12:30 AM
jrb
jrb
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There is definitely a difference in the blade shape of the E versus a Zinger!

Was too fast at flight idle with 15x10 E; wanted less speed looked long and hard at the Zinger before plunking down $10 for a 15x8.

Pulled nearly theamps of the 15x10 E but had now power/thrust at flight speeds!


Got the 15x8 E and a brown Sharpie and couldn’t be happier!
Jul 28, 2006, 07:00 AM
Rather be Hover'n
Redbeardrc's Avatar

Confusion


Folks,

Maybe it's me, but I'm having problems determining the correct line to balance her on and what the motor down angle should be on this plane. Any advice would be appreciated. The instruction manual doesn't really go into any detail on this. I've been told that it should balance to a line between the prop and the elevator hindge, but that doesn't look right either.

Please help level me out.
Jul 28, 2006, 11:05 AM
Registered User
JRB,

You said that the Zinger 15X8 pulled the same amps as the 15X10 APCE but had the power/thrust at flight idle. What do you mean by that.

I'm using an AXI 4120/18 and have a 14X10 APC E and a Master Airscrew 14X8 which pull the same amps on the ground. I haven't flight tested these yet. I also have a 14X8.5 APC 3 and a 13X8 Zinger which I plan to try. I want a scale looking prop that flies scale speeds.

I now have tests with the above props:

14X10 APC E-1093 watts at 57 amps
14X8 Master Airscrew wood-1090 watts at 55 amps
14X8.5 APC E-845 watts at 45 amps
13X10 Zinger wood-855 watts at 44 amps

I've flown the 14X8.5 and the 13X10 Zinger and the in flight performance seems the same. I don't want or need to put any more current through the motor. With these props, the plane is overpowered and I only fly 2/3 throttle at most. I've finally settled on the 13X10 Zinger only because it's wood and has scale appearance. The H9 Cub is a beautiful flyer.
Last edited by Eplane65; Aug 22, 2006 at 04:06 PM. Reason: New data
Jul 28, 2006, 11:39 AM
jrb
jrb
Member
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“now” is typo for no!

The Zinger ran out of thrust quickly as the flight speed increased – worst take-off I ever had with my cub.

Glow turns up at roughly twice the rpm of E; probably why Fred/APC has such a different blade shape for E vs. G.

I actually think the brown of the Sharpie looks more scale when walking the flight line and during a fly by than the Zinger too!
Jul 28, 2006, 07:02 PM
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rc-eflyer's Avatar
Quote:
Originally Posted by Redbeardrc
Folks,

Maybe it's me, but I'm having problems determining the correct line to balance her on and what the motor down angle should be on this plane. Any advice would be appreciated. The instruction manual doesn't really go into any detail on this. I've been told that it should balance to a line between the prop and the elevator hindge, but that doesn't look right either.

Please help level me out.
Usually you want to use a line from the trailing edge to the middle of the leading edge of the main wing as a reference for CG. Mine balanced about a 1/4" behind the suggested 3 1/4" mark and it seems fine. No noticable trim needed for level flight. Not sure what you mean about motor down angle but the firewall is your reference there. If you noticed, the stock glow engine motor mount had no built in thrust angles.

Steve
Jul 28, 2006, 11:01 PM
Rather be Hover'n
Redbeardrc's Avatar
Thanks Steve, that helps give me a guide line to follow.

I did notice the stock mount was 90 degrees to the firewall and the mount I made was done the same way. However, when we tried a washer on each of the top bolts, the down and to the right thrust angle that created definately improved the handling.

-Dave
Jul 30, 2006, 02:41 PM
Registered User

Scale functioning J3 gear


I just put a set of these on my Hangar 9 40 Cub. They are excellent quality and cheaper than Robarts.

http://www.piperj3gear.com
Jul 30, 2006, 11:26 PM
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rc-eflyer's Avatar
Quote:
Originally Posted by red apache
I just put a set of these on my Hangar 9 40 Cub. They are excellent quality and cheaper than Robarts.

http://www.piperj3gear.com
I'm considering those myself. Were the axles the right diameter and length to fit the wheels that came with the kit and also what did you use to paint the gear? Thanks

Steve


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