Old J-3 cub Build Old Power System/New Twists

[E-Challenged]

I'm gathering up stuff to finish my Sig 1/6 Scale J-3 Cub that I started over 30 years ago. I'm going to try to use an Astro Flight Geared 25 Cobalt and old AF 211 speed control ( no BEC), a Kool Flight UBEC to power the servos and powering the servos separately via the SPC port on the Hitec Optima 6 receiver. Battery packs will be two 2200mah 3S packs in series for around 25 volts. This motor and battery packs are heavy but the 6 foot wing will probably make this a scale-like flier. I am also building a clip wing for the model. I am attaching a rough schematic showing the motor/esc/bec/receiver hookup as coordinated with "Alan T" Hitec guru.
I am covering this model with Solartex from Balsa USA and using the E-Flite Super Cub 25 G articulated bungee landing gear, perfect size.

Detailed build thread here: http://www.rcgroups.com/forums/showthread.php?t=1754853

[kyleservicetech]

Originally Posted by E-Challenged

I'm gathering up stuff to finish my Sig 1/6 Scale J-3 Cub that I started over 30 years ago. I'm going to try to use an Astro Flight Geared 25 Cobalt and old AF 211 speed control ( no BEC), a Kool Flight UBEC to power the servos and powering the servos separately via the SPC port on the Hitec Optima 6 receiver. Battery packs will be two 2200mah 3S packs in series for around 25 volts. This motor and battery packs are heavy but the 6 foot wing will probably make this a scale-like flier. I am also building a clip wing for the model. I am attaching a rough schematic showing the motor/esc/bec/receiver hookup as coordinated with "Alan T" Hitec guru.
I am covering this model with Solartex from Balsa USA and using the E-Flite Super Cub 25 G articulated bungee landing gear, perfect size.

Detailed build thread here: http://www.rcgroups.com/forums/showthread.php?t=1754853

Yeah
I've had a number of those Astroflight brush type motors ranging from their 05, 15, 25, 40 and 90 motors. All were geared.

One of my models has had a variety of motors starting with the geared 40 Astro motor and 22 2400 mah Nicad cells to the current Hacker A50-12S motor with a 6S2P A123 pack. The Hacker is a direct drive, no gears to wear out in one years flying time.

Going from the Astro geared 40 to the Hacker A50 motor resulted in much more power at the prop, ALONG WITH near double flying times. Seems impossible, but that's what I got.

The Astro 40 Geared motor was used with a 13X10 APC-E prop, the Hacker is used with a 15X10 APC prop. The Hacker turns its 15 inch prop near 1000 RPM faster than the Astro motor and its 13 inch prop. The Hacker motor hauls my scratch built 8 pound model straight up out of sight.

Nuff said.

[E-Challenged]

If using the AF25 geared etc is too heavy for scale-like flying, short duration, etc. I'll change to much lighter brushless power. Plenty of room to achieve proper cg without adding nose weight.

[kyleservicetech]

Originally Posted by E-Challenged

If using the AF25 geared etc is too heavy for scale-like flying, short duration, etc. I'll change to much lighter brushless power. Plenty of room to achieve proper cg without adding nose weight.

That's what I'd do. It's not a matter of power, you can always put a smaller diameter lower pitch prop on a brushless motor to get the scale like power you are after. And, that results in a much longer flying time than the same system with the brush type motor. (Been there, done that. My first Astroflight motors were purchased in the mid 1980's)

[BradT]

E-Challenged, I used a similar setup in the D VII seen in my avatar, back in 2000. The model weighed 10 lbs, span 75", WL about 16 oz/sqft. I used the Astro 25, with a custom fitted MEC 4:1 gearbox, 20x2400 nicads, and a 22x10 wood prop. The model was not over powered, but had more than enough oomph to do scale loops and rolls, and an easy 8 min. flight time, with enough left for a go-round, if needed. A meltdown of the esc (not from overload) caused a fly-away and crash in 2002, and the plane still awaits a rebuild and updated power.

Brad

[E-Challenged]

If interested here is my build finishing thread on RCG:

http://www.rcgroups.com/forums/showthread.php?t=1754853

Have been mounting servos in wing and fuselage, trial fitting the E-Flite Super Cub bungee landing gear and getting ready to lay out wiring and panel the cabin, make seats, etc. Expect model will weigh about 6 lbs and fly like a Cub based on all the input I've been getting.

PS: Caution! Don't plug power into Optima receiver SPC port with wrong polarity, almost fried my Kool Flight UBEC!!!

[E-Challenged]

Deleted accidental duplicate post

[E-Challenged]

Update: I have the false floor with seats, sticks, rudder and brake pedals finished plus I have throttles, trim, carb heat and fuel controls installed in side panelling. I'm going on to finish external fuselage and tail feather work and wing stuff in preparation for covering and final assembly ( I made a long list of inter-dependant things to do in sequential order so I won't have to undo and redo ( hate that!!) Looks like another month of stick to it work. The E-Flight Super Cub 25 bungee landing gear ($18) looks like it was made for this model. I have a Carl Goldberg scale-type sprung tailwheel assembly on order, looks like the picture. ($20)

BTW: This 6-foot span Sig RC-3 Cub kit still costs only $88 on Sig's website. The kit is quite complete including hardware, decals, etc. Does not come with dummy engine, it's a true traditional scale stick-model builder's kit, originally designed by Chuck Hollinger and sold by Berkeley. Chuck passed away last year, was a member of Harbor Soaring Society, club in Costa Mesa, CA.If you build it, might want to build it as a 2-piece wing version. Sig also sells a "clip-wing" version for $96 and a kit to build an optional clip-wing for the stock Cub for $29. I have the clip wing kit and will build it later