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Feb 25, 2004, 07:06 PM
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exempt's Avatar
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World models Piper J-3 Cub 26 WHAT MOTOR?


I have a Piper Cub 26 that is rated for a .20 glow (2-stroke) that I recently put a Mag Mayhem in (direct) and it got it off the ground but BARELY. I know that a gear will help but would really like to go brushless with this one, what motor would be nice and strong in this bird? I was thinking an AXI 28/20/10 maybe? I am in the process of RE-covering it, the fabric type covering they have on it is nice and scale looking but man is it HEAVY! Thanks for any ideas.

Scott
__________________________________________________ _____________________




Piper J-3 Cub 26
One of the smallest ARF Cub on the market.
Covered with hand iron-on covering film.( Ultracote or Solartex )
Comes with pre-painted ABS cowling.
Top quality balsa and plywood construction.
Built-up wings.
So stable that you can fly it as a trainer.

Specifications:
Wing Span: 51 in. / 1300 mm.
Wing Area: 418 sq. in. / 27 sq. dm.
Flying Weight: 4 lb. / 1800 g.
Fuselage: 33 in. / 838 mm.
Radio: 4 channel 4 servos
Engine: 2 stroke .20
4 stroke .26 cu. in.
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Feb 25, 2004, 08:38 PM
Visitor from Reality
Sell it to one of those guys every club has, that will buy anything ready made. Probably go even quicker if you can stick a glow engine in it.

Then, if you want cheap and small, put a gearbox on your MM and build yourself a Great Planes ElectriCub, which will even fly well on all of seven cells and much better on 8.

If you want a little bigger, get that AXI and attach a Sig 1/6th long wing J3 kit to the back of it.

The GP E-Cub has a longer span than your BARF Cub, but weighs about a pound less with a battery installed - flies great, I had one when they first released this present version.

If you want bigger still - that's my 1/5th Sig Cub to the left. I can't carry a 1/4 scale Cub around in my little wagon - bummer!

D
Feb 25, 2004, 10:04 PM
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exempt's Avatar
Thread OP
Thanks for the reply Dereck, lots of ideas there! that great planes E-Cub would have been the way to go I'm sure, but seeing as this was given to me and now that I've ripped the covering off the wing and fuse I am now determined to make it electric worthy, I'll probably do some structural changes as well to make it as light as possible before I cover it, the weight savings in covering alone will be quite a bit I'm sure. (and it won't be yellow either, thinking a nice metallic green and pearl white?) But anyhow I guess I'm going with the AXI on 8 to 10 cells, or maybe something more powerful as I wouldn't mind overpowering this one.

Scott *exempt*
Feb 25, 2004, 10:32 PM
Destructive testing expert!
Bill Sanford's Avatar
I've got an AXI 2820/12 running on 10-HECELL 1800mah and it performs VERY well with a 12x6e using a Phoenix 35.

I'm using it to pull around a stick built T3D from Aero Craft (http://www.aerocraftrc.com/). It's a Tom Hunt design that weighs about 2-1/2 pounds.

With the 10 HECELLS thrust about equals weight. With a 3s2p ThunderPower pack made with 2100 mah cells, it's got lots more "get up and go"...

This would be a great motor for your cub. If you want more power you could run 12 cells, which this motor should handle with ease. Mine barely gets warm after a 15 minute flight with the 3s2p TP Li-Poly cells...

I'm thinking about a BIG cub with an AXI 4130/16. Check out my thread on this big AXI I'm also using in a Funtana 40s and you'll see it has plenty of motivation as well...

Good luck

Bill Sanford
Feb 26, 2004, 10:37 AM
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exempt's Avatar
Thread OP
Thanks Bill! I think you're right, the 12 would be better than the 10 as I can run more cells with it. OK great, I will post a pic of the cub when I get it re-covered, it will be interesting to see how much weight I can save.

Scott
Feb 26, 2004, 01:04 PM
Ay up it's warped
mtbrider's Avatar
I am surprised at the Mag Mayhem not pulling but I guess it needed gearing. My 72" Flair Piper cub flies on a geared Hurricane 650 brushed motor using 10 cells. Get 10mins out of 2400 cells on 3/4 throttle, 7 mins from 1700s
Feb 26, 2004, 04:20 PM
Registered User
exempt's Avatar
Thread OP
Well it WOULD fly but not very well, maybe 8 cells and a larger prop would have helped (I only had it on 7 SC's) I wonder how big of a prop you could manage on a mayhem direct, well I suppose I could try a gear
Feb 26, 2004, 08:51 PM
Visitor from Reality
Lucky for you - I file all my Traplet mags!

March 2001 "Electric Flight International" (before it caught g!*#@rs). My review of the GP E-Cub - the present kit with ailerons.

This kit is touted as flying on either a DD or geared ferrite as peddled by GP. DD is good for a paperweight in this type's case IMO. It needs a lot of slow moving prop shifting a lot of slow moving air back, and DD can't cope. An 8 x 4 could be close to converting your MM to a paperweight, a 9 x 4 almost guarantees it.

The GP E-Cub is 59" span, and IIRC, mine ambled off the deck at around 54oz, maybe a hair less. I used both the GP ferrite as they offer for this model, and a Mag Mayhem reverse - not a lot to choose from, but the MM has a nicer lable This used the GP gearbox - not bad for the price, don't catch a prop tip or you'll find out why early E3D pilots all went flying with this box and several spare spur gears ...

Used a 2.5:1 ratio, 10 x 8 MA prop - now would use APC-E for flying - and seven cells - probably SCRC 1700 (there was a goodly supply of ex gov't 1700s around at an irresistable price back then ).

It acted like a Cub but an extra cell would have improved matters considerably. Aerobatically, it was Cub-like - odd shaped loops, a roll if you persisted and it would reach vertical for a stall turn if one persisted. The wing was technically cantilever and the struts sort of part decoration/part handy - but I would not fly one without them, as they do a little to keep the ultralight wing from flapping around.

You might be able to download the kit's manual off GP's website - it has an ingenious solution to loading the battery pack through the bottom, for one good idea. If you could incorporate this into your ready-built, it would save a lot of grief over a 'top loading' solution. There's probably quite a few other tricks you might find handy if you can get a copy of the manual.

A geared ferrite, 8 jugs, around a 10 x 8 or 11 x 7, lighter covering, a hot number played by Mr. Dremel and his Little Sanding Drums, you could have a fast-ish, but otherwise Cub-ish flier on your hands.

Minor "snag city" - the MM comes in forwards and reverse models. If you put a gearbox on a 'forwards', and run it what amounts to backwards, you will soon experience Severe Grief in the brushes and not all that much in the "Go" dept beforehand.

Sorry.

You can re-time a MM forwards into a backwards, but it struck me as complicated ... Alternate is a 'box or beltdrive that doesn't reverse the prop rotation from the motor rotation. If Hobby Lobby still sell the "Olympus" beltdrive, this could be what you want - it's cheap-o and works.

As is often the case in e-flight, you can either get ingenious or spend a lot ...

Regards

Dereck
Feb 26, 2004, 10:10 PM
Registered User
exempt's Avatar
Thread OP
"As is often the case in e-flight, you can either get ingenious or spend a lot ..."

Yes Dereck you're so right! that should be inscribed on a plaque somewhere. I do have a pretty strict budget so tend to get creative quite a bit, although I did splurge a bit on my Dynamic (the one in my avatar) I think I will try one of the Olympus drives before going to brushless just for curiosities sake. My cat decided she wanted to try RC and knocked the plane off my work bench! just slightly broke the horizontal stab, but an easy enough fix. Thanks for all your input, pics are coming soon.

oh yea, I LOVE Traplet mags! I just wish it was cheaper to subscribe here in the US. (the US mags should really take a hard look at how the Europeans do it, much better in my opinion.) Great article on float design in the Jan 04 issue of Model World!

Ok, off now to find a copy of the GP E-cub instructions.

Scott
Feb 27, 2004, 08:09 AM
Speed Demon
GregG's Avatar
Quote:
Originally posted by Dereck
.......

As is often the case in e-flight, you can either get ingenious or spend a lot ...

Regards

Dereck
Well put Dereck!
Feb 27, 2004, 10:06 AM
Visitor from Reality
TVM guys! I'm trying hard to revert these days...

Not sure why the difference in mags. I can recall when I started flying "full size" in the RAF that all aeromodellers on base where about required to pick up any US mags going on trips overseas - thankfully, every US base has a "Stars and Stripes" bookstore which carried amazing magazine selections.

We all thought that the plans in the US mags - RCM was the easiest to get - were great. Usually two, sometimes three of them.

The annoying part was how the articles were split up around the ads! Funnily enough, all the established mags have pretty much quit that, but the newer ones seem prone to it ...?

The Brit mags - the cost is down to having to haul them over the Big Wet Bit. I'm guessing we're not quite at where a mag could be electronically transmitted from England to the US and printed here, or at least it's not financially viable.

Two small units of currency? The better mags have a higher proportion of active model fliers in their genre, from editor to columnists. Start bringing in businessmen who don't know a tailfin from a nosewheel and there goes the neighbourhood.

Scott - the Oly beltdrive has a long history and a dedicated following - must make it worth its fairly trivial cost by modern standards. I've flown a friend's Sig LT25 on ten sub-c cells and a geared MM, and that's about the same amount of model as your Cub.

I'd be inclined to suggest you look at 1950 FAUP or those HECELL mentioned above, as they cut down on pack weight enough to make one pay attention. LiPo are a neat trick, but I'm sitting on that particular fence for a while longer until they settle down some.

Good luck with your project.

Regards

Dereck
Feb 27, 2004, 04:26 PM
Ay up it's warped
mtbrider's Avatar
quote:
--------------------------------------------------------------------------------
Originally posted by Dereck
.......

As is often the case in e-flight, you can either get ingenious or spend a lot ...

Regards

Dereck

The Hurricane motor costs about 6.50 and the MPJ gearbox about 15, I don't like the price of the batteries but they are cheaper at the moment to Li=po/poly. Must admit that I do not expect a long life from the motor. When it dies I am considering one of Fanfare's buggy type motors. Apparently wound by a chap who lives in Chesterfield. Which is nice.
Feb 27, 2004, 05:36 PM
Visitor from Reality
You have to be philosophical about batteries...

Either divide the cost of your pack(s) by the cost of your favourite / previous alternate fuel (glow or diesel, petrolgas is cheating!) per gallon - or forget about it!

I get 15 mins of Cub like flying from 16 3000 mA nimh in that monster I'm holding to the left of this lot. By then, am bored silly.

Add to that, I land, throw my cooling fan (ex-antique computer) into the fuselage to cool 'em off, hook up either of the chargers I've owned for well over three years now, and let it get on with recharging them at 3 - 5C. Then, I eithe rgo fly something exciting or have a cuppa and pick holes in someone else's flying.

With LiPos, I'd have to pull them out of the model, sit them in a fireproof container and stare at them while a charger I'd have to buy dribbles electricity in at 1C.

I ask myself - do I need to spend another 300 - odd clams to be able to fly her for 25 mins?

Not on your nelly

Based on the cost of ferrites, and how long Astro's last, I'd be inclined to keep my eyes open for used, low mileage AF cobalts - either the 035G or 05G replace your average 500 -600 ferrite, with the added bonus of being very close to everlasting. My 035 has been caned something wicked for the last six years or so, on ten cells and 30A - not a cheap motor, but surely an economical one.

We had a real wally in our club a while back. He carried his collection of ferrite motor flux rings around with him! Every time he melted a cheap ferrite, he'd add its flux ring to the collection and mail-order another. We think he passed the cost of an Astro 035 at around ferrite #4 - he had 6 flux rings last I heard. Pre-common breathless motor prices, BTW.

Sooner or later, will be off on another 8 - 10 cell close-ish to scale sports model - it'll have one of my AF cobalts in it, yet again.

But I wouldn't buy a new one, just in case you're wondering ...

"Over Here", the CP2400 is about as cheap as sub-C has ever been for new cells. Not as sexy as the current rash of 3K nimh, but no mean cell at all.

D
Feb 28, 2004, 08:24 PM
I think if you just gear it on 7 cells it will surprise you. mine leaps off the ground in 30 feet on a green speed gems on a greatplanes geardrive and seven kan 1800 hitec 81's light reciever. some lightening. I think it weighs just over 3 lbs.
Mar 01, 2004, 03:17 AM
Ay up it's warped
mtbrider's Avatar
Dereck, I am with you on the battery issue. I had a glance at fireproof safes the other day. I has not impressed with having to pay out for one of them, a charger and new batteries even though I understand the benefits of LI-po/poly. I like my hobby but I love my family and rather fond of my car. It gets me to work to pay for it all! The Fanfare motors are in the mid 30's which I do not mind, as you say 6 ferrite motors or so. Will keep a look out for an astro until I am ready to re-motor though, the Buxton swap meet is in a month, see what I can find there.
The Cp2400 had more power than the 1700s that I borrowed of a friend to see if it flew better on a lighter battery so I purchased some more of them.
Cheers
Mark


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