Just Bought a Sig 1/4 Scale Cub (105" w.s!) - RC Groups
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Oct 29, 2004, 08:09 PM
Acer's Avatar

Just Bought a Sig 1/4 Scale Cub (105" w.s!)

I just bought a 1/4 scale Sig Cub and was wondering what, if any, would be the right motor for this plane.

Most guys use around a 26cc gas engine in this plane. The plane has a 105" wing span and will weigh between 14-16 lbs. I was just wondering if it would be practical to make this an electric, or if I have to go to gas.

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Oct 30, 2004, 10:07 PM
Just fly,its just money.
oo well. i tihnk u could turn this plane into an electric but i wouldnt. it would cost alot more than u would want too. i think u should go with a glow. i have a the sig scale cub. not this one. but the 1/5 scale. i think u should go with glow. maybe gas. i think a saito or maybe a super tiger. those would be sweet on there. but get what u want. good luck and safe flying.
Oct 31, 2004, 01:24 AM
Registered User
Brad Trent's Avatar
I've seen a number of Cubs, SuperCubs, and similar planes, such as Taylorcraft and Aeronca K, at this size, powered with electric. All of them used the Astro 90G on 36 sub-c cells. These were built and flown before brushless and li-po cells existed, so I'm sure that there are better motors and batteries suitable for a project like this today, but the planes I saw flew very well, indeed, on the "old tech" systems. Bob Benjamin's Taylorcraft (should come up on a search in these forums) flew and looked great enough to get him invited to Top Gun more than once, and his Aeronca went to the World Scale meet in canada a couple of years ago. Randy Smitheislers large Cubs have also competed in Scalemaster events,and I think he took one to Top Gun on one occasion, also.

My own Cub is the H9 1/5 scale, about 81", at just over 10 lbs RTF, and uses An Astro 40G on 20 cells.

Last edited by Brad Trent; Oct 31, 2004 at 01:27 AM.
Oct 31, 2004, 06:13 AM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar

Some ideas for powering 1/4 Cub:
https://www.rcgroups.com/forums/show...owered+aerotow Sig 1/4 Cub

And Benīs Super Cub: https://www.rcgroups.com/forums/show...=DPM+Super+Cub


Oct 31, 2004, 07:39 AM
E-flyer since 1981
Michael in Toronto's Avatar
I have the 1/5 scale Sig Cub, and it flies superbly on electric. I'm using a Kontronik 5.2:1 geared brushless motor on a 4s4p lithium battery pack (power equal to about 14 or 15 nicads, but much less weight) and it can fly for nearly 20 minutes. It cruises easily at 1/2 throttle.

If the 1/4 scale Cub is similar, it should be a good flyer on any 20 to 30 cell motor system, say a geared Hacker B50L system or maybe an AXI 4130-20.

It is true, that your initial cost will be high (motor, speed controller, batteries- - especially lithium batteries and charger).
Oct 31, 2004, 12:21 PM
Acer's Avatar
Thanks everybody. So I guess it is possible. Now I just need to do some research and see how much of a hit to the wallet it would be and compair that the a gas setup.

-- Acer
Oct 31, 2004, 06:33 PM
Visitor from Reality
That's my 1/5th Sig Cub in my avatar - it ambles around Cublike for 15 mins on 16 3300mA cells. On 20 cells, it was hard to stretch the take off past a couple of yards and it was grossly overpowered. FWIW - 8lb 2oz with 16 cells, which is about 34oz of battery, but costs a lot less than lipo and doesn't have lipo's unfortunate failure mode of bursting into flames . Got a 16 x 8 doing something like 6,000RPM on the front.

As long as you want to make your 1/4 fly like a Cub, I think you could get by on 20 - 24 cells of the old nimh variety. The two folk who could set you on the right track are Tom Cimato at www.maxcim.com - he makes the motor in my Cub, which can handle 24 cells - or Pete Peterson at MEC - http://www.modelelectronicscorp.com/

While there are others who sell drives to favour the wizbang world of hovering and other such strange behaviour, those two have a wealth of experience in providing brushless systems for sports and scale models.

If you don't want to spring for BL, try Tom Hunt at ModelAir- Tech - http://www.modelairtech.com/ Tom's got a humunguous Cub on one of his beltdrive systems and ,again, a wealth of knowledge about this sort of model and his DeWalt drill motor on one of his beltdrives is a very reliable rig.

Thought for the day - Nothing this size comes cheap!

Nov 01, 2004, 12:59 PM
Registered User
Larry Dudeck's Avatar
What Derrick said about Tom Cimato.

Do a search on "Paul Martin" here. Has has built a number of large planes using the Maxcim motors and controllers.

Speed demons they aint but, then again, Cubs were not meant to be fast.
Nov 03, 2004, 04:22 PM
Registered User

Sure love those Cubs

I think I can help this discussion here since I have a Sig 1/4 Cub and have had 3 of the 1/6 scale Sig Cubs.

First, for Dereck, I like to fly my Cub in a scale like manner. No you cannot see the engine or muffler, and it is very easy to clean. The Super Cub cowl hides the big ugly engine. Mine is the Clipped version and it has a Quadra 35 gasser in it. It weighs 15 pounds even. I can fly it at about 1/4 to 1/2 throttle and if flown at the right distance it looks like a real one off in the distance. Even at that weight it floats on landing so care must be taken. As far as the engine, yes it is TOO LOUD! I fly at a field that is very remote but even the slimers hate it because I can fly about all day on a tank of very cheap gasoline, and they even get tired of the noise. I am getting about 6700 rpm out of an 18x8 prop so you can use this as a comparison.

Now for the reason I am writing.

I had originally decided to electrify the Cub and I still feel that I could get the same performance, and the quiet. I have weighed the electric system and I really think it would be the same as the gasser. I am talking about an Astro 60 w/superbox and 30 or so gp3300's. I am not sure but I would guess an 18 to 20 inch prop would work quite well. I love to experiment so maybe someday I will pull the gasser out and put in the Astro. Heck I might even try the same prop.

My opinon is that electric will work very well in your Cub.

Nov 03, 2004, 04:53 PM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar

My 1/4 Cub has endurance closer 40 min time with 10s2p K3270mah cells, and it weighs just 6,35 kgs, wich is not much more than it was on
Saito 120 twin on its earlier days. Also flown it with Sanyo 3000HV
30 cell pack, but switching into lipos make it work really great!

I prefer flying it mostly with Menz 19x8 wooden prop, 5700rpm/38A
While flying in scale contests against similar 4-st powered Cub,
it was quite amazing how much easier it was to reach "right scale speed",
ie I could control much more accurately rpmsīs over the glow powered.
So very linear and accurate throttle control including very high torque makes electric very
good option for scale flying. And when using outrunner, judges dont hear you pumping throttle in trickly places, so maybe it feels more accurate..?

Below some videoclips of aerotowing with my Actro 40-6 powered Sig Cub


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