My Sig Cub - now its for real! - RC Groups
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Nov 10, 2002, 09:32 PM
Visitor from Reality

My Sig Cub - now its for real!

Hi Folks
Following a spell of housepainting - actually, watching a bunch of guys with paintbrushes who didn't speak English and didn't mind missing all sorts of things - a family visitation and some other odds and ends, I realised that I had nothing "under construction" in my shop.

So out with my Sig Cub, the 1/5th laser kit, spread it all over everything and get going.

First impressions.

If you're used to plans or "own design" building (or even some kits), this kit is a BARF with lots of parts! I clipped the fuselage together, holding it with masking tape, then checked it for truth.

It's all straight and true, sitting there waiting for me to add the thin CA. The parts fit is really that good.

The firewall is the only real work I've had to do, and that's because I have to design a way to get my chosen MaxCim 13Y out to the propface. The MaxCim on its mount is a goodly bit shorter than a glow engine, so I'm cutting out a thinner firewall - 1/8" ply will do, vice the kit's 1/4" - with a box to move the motor forward.

My dear wife Sue is insisting that I go buy a digital picture box tomorrow, so I should be able to post some build-up shots soon, if anyone gives a hoot.

The hardware list right now runs to the above MaxCim 13Y, 4:1 ratio, 20 x 2000nihm cells - I have them handy, they are lighter than big'uns and will allow me to fly the model in Cub-like fashion for around my boredom threshold level at Cub-like flying. I'll also have the power to take off Charlie "The Flying Farmer" Kulp if the urge strikes. This drivetrain was carefully decided upon after hours of confusion amongst the drivetrains used in similar sized Cubs hereabouts (12 to 21 cells, S700 to AF40 motors!) and calling Tom Cimato for help!

A side benefit is that I can even fly on a scale diameter prop!

RC gear will be Hitec 225s in the fus, ditto, or 81MGs if my nerve holds, in the wing with whatever RX allows me to use a Deans whip and mixed aileron servos.

It won't be all yellow - the odd looks of the clip-wing made me decide to go with the long wing, but I have to make mine look different from the zillions of yellowBARF Cubs. There's two candidates in Banka's range - a military green J3 and a blue/yellow USN J3. Rumour abounds in Louound County, VA of the Lenape three cylinder J3 - hopefully, they'll even build it this winter so we can have a Cub-In at the DC Metro E-vents.

The next decision - do I use the wire kit gear, or spring for an after-market sprung and more scale-like unit? Robert do one, plus there's someone who advertises in RCM - his features scale bungee covers, which Robart's lacks.

I suspect I will fall for the latter - anyone any experiences here?

I'm really going to shift it with this Cub - it's so big that it's dominating my entire shop right now!


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Nov 11, 2002, 02:37 AM
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Gerald's Avatar
What, no digital picture box? Dereck I'm shocked! How could you get by this long without one? Yes, pictures please!

It's great to hear that you are actually building from a kit like so many of us mere mortals . But I bet that you won't be able to resist the urge to leave well enough alone. Doesn't that military J3 have a great big greenhouse? I bet that would provide a little challenge .
Nov 11, 2002, 02:47 AM
Registered User
HOOT! piccies please!

Nov 11, 2002, 07:51 AM
Veni Vidi Volavi
Brian Allen's Avatar



Good to see you on Saturday at the NVRC Toys for Tots flyin. Sounds like you are indeed getting serious on the Cub. Would be interested in some photos if you can figure out the instructions on the new digital picture box. Always wonder about those since most of us can't set the clock on our VCR's!!!!!!

Interesting thought re the LG, hadn't even considered that as part of the build. Let me know what you finally decide to do if you use an aftermarket gear. Would make it lok better.

Hope to get started on mine towards the end of the year as soon as I finish a couple of other projects I have promised people. Ron will make up the new cowl and cylinders for the Papoose.

Gerald While the vast majority of the L4's had the extended greenhouse, the earilest batches of the L4 were simply stock J3-C-65 's taken from the civilian production and either painted bright yellow or OD and fitted with a radio. Wasn't until the ARmy had taken delivery of several hundred that Piper started to provide the greenhouse which obviously made observing easier!!

Brian Allen

Veni Vedi Volavi

I came I saw I flew
Nov 11, 2002, 10:38 AM
Visitor from Reality
Hi folks
There was a BARFer Cub at the Loudoun County E-Vent with a sprung aftermarket gear - sorry, can't remember the builder's name right now, but he'd done a nice job of converting the mandatory all yellow to a USN E-1, which was all yellow with stars in circles and a stripy rudder. The gear adds around $100.00 but really looks the part. As I'm aiming to put some effort into scale detailing, though much will get added post-flight testing I'm sure, this might well be worthwhile.

To anyone who's contemplating this one, my chosen MaxCim is going to need around a one inch stand-off from the kit firewall, using the MaxCim mount, to get the right prop position. I can actually get the MaxCim into the right position using an AeroVee small mount, but motor rotation in them at 600W can be a problem. For all that, it simplifies mounting. An AF25/Superbox on an AeroVee about makes it to the right position. The artistically inclined could actually move the firewall forward in the cowl by adding on to the fuselage side lengths and doublers by however much is needed. I've started thinking about that route too.

As I have a thing about flying scale models like they did at full size, having the battery low down in the fus is no real gripe. I'm hoping that this will allow some cockpit detail to be fitted. Thank goodness for the scale opening door and window - this one has no top access like the one-piece wings of the BARFCubs, so all detail will have to be poked in through the door.

Yes, I could fit it before building the top of the fuselage but I don't know exactly where the pack will go and, more importantly, I actually want to fly her, not spend all year building the dashboard

Still have an irrational urge to convert her to a P-11 with a full cover cowl. This involves dropping the thrustline 0.8" and building the new cowl, though technically speaking, I'd have to build a larger door / window as well.

If anyone is contemplating this kit - one, it is superb. Two - the fuselage looks to be the most complex single piece, though my dithering over modifying the firewall has cost more time than assembling the rest of it. However, there are some real big bits to come (wing panels) and rigging her is probably going to be done in the garage using my Workmate and a door as a temporary facility.

It is getting more power than it needs, because I have the battery and scale models are always better for having a sensible reserve if it doesn't hammer the weight too badly. Have seen a Cub loop, roll and spin, and that loop would take a lot of grunt to do from slow flight - even if it was a "Figure 9".

Digipics? Mostly, I haven't needed to. As the mag I write for is in England, it is still easier to ship them paper prints, which they seem to prefer anyway. If I need a digital image, I just slap a print on my printer/scanner/copier (when will they incorporate a coffee pot?) and make one off that. Going digital to paper is either very expensive (to photo print standard) or time consuming. Still, wifey feels we need one and I've talked her out of the toy camera level at least.

Failed to talk her into a digital Canon SLR body though

Then there's the Cub meet down at Williamsburg, VA, September-ish ... Brian - Your Lenape and my J3 ??? would make a splash cruising around in peace and beauty at that. It's another Toys for Tots meet too!

Side note - electrics really showed up good at the NVRC Toys for Tots Saturday, and in "Mixed Company" too.


Nov 12, 2002, 09:43 AM
Visitor from Reality
Hi folks
Well, the camera shop guy did a great job of demo'ing me several digicams costing far more than Sue was contemplating, until she remembered that I have minor claims to being something of a photographer and would be unlikely to be seen dead in public carrying a "Big Box Special" happy snapper .

Shame the guy sold me on a neat Olympus that they were out of stock on. In another fit of customer service, he promised to call me as soon as they got stock, and haven't heard back since.

So no Cub piccies yet.

Points so far. Sig have you bolting the neat sprung tailwheel assembly to the balsa fuselage bottom sheet There's a ply doubler on the inside, to accept the blind nuts, but the spring is actually resting on balsa - which will squash as soon as you tighten up the tailwheel bolts. I've replaced the back end of the bottom sheet with Liteply - heavens knows, there's enough 'spare' Liteply in the kit and its all the best stuff I've seen.

The other is the old bugaboo - mounting the motor. If I use the MaxCim mount, I'll need to build a 1" deep stand-off onto the firewall's 1/8" copy.

If I use an AeroVee MM1, I can get away without a stand-off, but am wary of putting 600W into an AeroVee as there's a chance the motor can twist in the mount. Have thought of some kind of mechanical restraint against twisting from the motor front case's 'spare' 4-40 tapped hole to the mount.

So far, I have the kit firewall with lines and circles drawn all over it!

I don't plan on altering the tail feathers, but no way will my aileron servos be outside the wing.

Back to really working

Nov 12, 2002, 11:15 PM
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Gerald's Avatar
Dereck, I use an Aerovee mount in my Kadet Senior at up to more than 800W with a big 16"x10" prop. I had to take some measures to prevent the motor from turning and twisting in the mount. The "Vee" in the Aerovee is not very deep so it is possible for the motor to twist from side to side. I epoxied a pair of 1/4" hardwood rails to the mount alongsides the motor to keep it pointing straight ahead. Then before tying the motor down I placed a couple squares of servo tape between the motor and mount to help keep it from rotating in the mount. The straps and cable ties alone weren't enough. Finally, I made a strut from a length of brass tubing tying the front of the gearbox back to the firewall. It's worked out quite well and seems to be holding up fine for over a year now of flying it nearly every weekend.

Click on this picture to see a larger image.

Here's a homemade mount I used on a Super Stearman. This was also used to handle the power of an Aveox installation at about 650 watts. If you could combine the "V" geometry double strut as shown here with the Aerovee mount then it would be even sturdier.
Click for larger image.
Nov 13, 2002, 09:28 AM
jrb's Avatar
Dereck, here's a shot of my Cub mount (and used on 2 other planes) for the MEC Super Box & 16" prop.

This keeps the prop centered regardless of ratio or motor changes.

Two mods were made subsequent to the photo: front plate is now aluminum and a 1/8" plywood stiffener (with holes) has been added above the top two dowels.

The aluminum front plate is required; the stiffener was tried 1st with no effect.

Basically, since the prop and motor are canterlevered off oposite sides, the front plate (though only 2.2"x2.2") flexed at high power loads -- Static. In the air it seemed fine.

I now have many flights on them with 15 and 16 inch props on 16 and 21 cell set-ups.
Nov 13, 2002, 09:55 AM
Involuntary Beta Tester

Re: My Sig Cub - now its for real!

Originally posted by Dereck

My dear wife Sue is insisting that I go buy a digital picture box tomorrow, so I should be able to post some build-up shots soon, if anyone gives a hoot.

Please document the whole build with pictures if you can. I learn a lot with pictures. "A picture is worth a thousand words".
This is what Ezone and the internet is all about.

Nov 13, 2002, 11:01 AM
Visitor from Reality
Hi folks
Unfortunately, the guy at the camera shop either didn't get stock or doesn't work on commission, so photos are still being done my favourite way Once I get this digital camera thing, I will post some additional shots, though the whole ball of wax should end up in a QEFI review article.

On the motor mount. I've gone with an AeroVee. The MaxCim 13Y fits it just fine, and I think I've figured out a way to keep the motor from twisting in the mount, with a tastefully bent piece of wire, a short 4-40 bolt and a couple of screws!

So far, it would have been too much work to strip a few gm out the balsa frame, the canopy is all ply and somewhat strategic (it supports the wing!) though I have knocked the firewall down from 50gm to under 40gm. I used the kit's 1/4" ply firewall rather than make a 1/8" ply copy - it's all cut far too accurately to go using knife-cut replacements willy-nilly.

The top decking from firewall to canopy will be made removeable. I figure the fuselage is stiff enough without it as permanent structure, given my vibe-free power, and it will provide usefull access to the ESC. That's sitting on the handy fuel tank plate, BTW.

I am changing the fuselage servo mounting. The kit has three standards servos mounted upright in the bottom rear of the cabin. These would stretch patience getting to them and are mounted on a lot of ply. I'm probably going to mount mine inverted in the back of the cabin, accessed from underneath. There's only two fuselage servos of course - though mounting the rudder servo centrally does make it easier to hook up the closed loop rudder cables.

The kit supplies all pushrod / pull/pull hardware, though I'll use kevlar thread vice the kit's wire, to allow for using a Dean's whip aerial fitted internally in the aft fuselage.

Next decision! Do I use a couple of handy standard servos on rudder & ele, with Hitec 225s on the ailerons, or get brave and use 225s in the fus, with HS81MGs on the ailerons?

I'm getting one of the aftermarket sprung UC assemblies for her. There's a choice of Robart's or one from a William Wallace who has advertised his wares in RCM for some years. The latter unit comes with bungee covers, Robart's doesn't. Anyone got any experiences of these sprung undercarriages ?

[B] Observations so far ? [B]

You'd have to look very hard to find a better quality of cutting and wood selection in a kit.

The instructions are fine - as long as you read them carefully, then carefully read the step ahead, just in case, and take equal care in assembly. They are describing how to assemble a big 3-D jigsaw puzzle in the case of the fuselage and many pieces might not fit if left until later.

You could build the model right out the box and it would make a fine electric scale model.

It is a 1/5th scale model, not an "IMAA Legal (just)" Cub shaped high winger. The wing span is spot on for 1/5th scale and it incorporates a lot of detail touches - the skylight in the roof is incorporated, though a tad under-width, for example.

"Piper's Golden Age", by Alan & Drina Abel, with Paul Matt, is invaluable reading for Cub-ites. Photos might be clearer, and colour info and more photos on the J3 shown dropping a guy off onto a truck would be invaluable (probably yellow / black). There's also a L4 with a trike gear and those who don't fancy painting a dummy engine might look at a conversion to a J-11 Cub Special (I'm tempted!).

Next comes the rear decking, fuselage doublers and stringers


Nov 14, 2002, 09:41 PM
Visitor from Reality
Okay, I've been slacking. Have stuck a lot of bits of wood around the fuselage, but it doesn't look much different yet.

For light relief, I "assembled" the fin and rudder. Took longer to find the pieces than glue them together, and that includes cutting some lengths of stick for the ribs. All the laser cut pieces have some form of jig cut into them, so they just lock up naturally, and the 'ribs' fit into notches (which were all the right size) cut so all the stick ends are square cuts. The tailplane is pretty much ditto of course.

It's nearly un-natural building like this!

I actually bought me a digicam today - an Olympus 730. Once I have figured out enough of its zillion features to reliably take a photo and get it to a directory on my computer, you might get lucky and see how this beast falls together.

For anyone hoping for a conversion revelation - this one is another Sig electric model, with only the alternate glow power plant drawn on the plan. Looks like the only big changes will be the firewall, radio fit - fus and wing - and I might redo the ailerons to make myself feel better. The kit's ailerons are fine for E-power but I have to mess with something ...

My wife's taking me to San Francisco Sunday, back next Wednesday. Real bummer Building will stagnate...


Nov 14, 2002, 10:25 PM
Veni Vidi Volavi
Brian Allen's Avatar

Sig Cub


Enjoy your trip to San Fran, hope you and Sue have a good time. Should give you enough time to fiddle with and learn how to use the Digital Camera.

We expect a bunch of photos of the Cub when you get back.

Really need to get started on mine!!!!!

Brian Allen

Veni Vedi Volavi

I came I saw I flew
Nov 15, 2002, 05:17 AM
Registered User
Dereck, good choice on the Olympus 730. I have the 700, and was sold on its 10x optical zoom, just about everything else I looked at was only 2 or 3 x optical. I had a 3 x optical, and found it just wasn't good enough for model aeroplane piccies.

Just another lot of money model aeroplanes have cost me


Peter from the state of Tas in the land of Oz
(Ex AF40G powered J3 owner)
Nov 15, 2002, 11:39 AM
Visitor from Reality
Hi Peter
Thank you for the confidence boost on my choice! So far, I've been through one set of AA's, haven't actually taken what could be called a photograph yet and have mastered turning it on and off, I think.

My Olympus OM2n was at least understandable. Do I need five fully customisable "personal picture modes" in addition to the usual array of program modes, plus the real photo modes. Did I spend all that, and it still has a real manual mode buried down there?

Still, Sue's happy - we now have a digital camera

Just built the top hatch on the Cub, fits inbetween the centre ribs what eventually take the wing joiner tubes. So far, about everything has fitted way above what I could dream about hand-cutting.

Have ordered a Banka Photopaak of a blue fus/yellow winged "US military J3". I aren't going to get overly passionate about going "scale", but want it to look something like a "real one". It'll all be Monokote, as I figure I'll end up painting some fiddly bits, plus the cabin interior, cowl and suchlike so compatible paint will come in real handy.

I think I'm going to get some waterbased clear poly varnish and seal all the woodwork to be painted, so one coat of paint should do it. Wish I'd had that thought earlier - there's a hint to anyone contemplating this sort of model.

I'd liked to have done the cabin first, but am not sure where the batteries will end up. Suspect the pilot will be cut off at the pass, can't see there being room for full seats and a full length pilot over the battery somehow.

Have to be strong - this model is intended to fly and be a little more stand-out than the hordes of yellow 81" Cub-ish devices, not something to attack Top Gun with.


Nov 15, 2002, 12:24 PM
jrb's Avatar
A CG thought:

Servos aft out of cabin, at least under the seat. Also use a separate bellcrank for the pull-pull; make servo changes easier.

Cells ahead of dash.

What type of pack configuration do you have in mind?

Here's a photo from a Kadte owner with an idea on how to get the cells further forward:

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