Sig 1/5 Piper Cub J3 converted to Super Cub

sts41 · September 21, 2012, 11:49:07 AM

Well today I ordered my winter project, a 1/5th scale Sig Piper Cub J3. This is an 84.5" wingspan and weights about 7.5 lbs...I am expecting the build to come in nearer to 9 lbs with the modifications. I selected the Sig since it is the only one I could find with split wing. And Sig quality is well known. But the price point was a lot higher than the GP plane. I was unable to find any Super Cub Kit that I liked....Would of had to stick build it from plans, and I am nowhere near having the equipment or knowledge to take on that sort of build.

I have seen a dozen colors schemes and will go with the Military colors since 1) It will work on Warbird Day, 2) Super Cub was actually more associated with the military.

I will be adding full lighting, Robart articulating landing gear, Dubro Cub wheels.

Power system is still up in the air...But I am looking at RimFire .80 with 75Amp Pheonix Ice ESC, 6S6000, spinning a 15X6 prop...This is overkill for land, but is needed if I plan to later put floats.

To modify this to a Super Cub, I will be adding Flaps to the J3 and adding the landing headlight in the cowl. I am still trying to decide if I will put the cylinder heads poking out the cowl..A J3 thing that is not on the Super Cub...But can be made to look great if you put a bit of work into it.

Both tail surfaces will be Pull-Pull with the Servos up front for weight distribution.

I welcome any input on this...I have built a few plane in my life, but nothing as big as this. I will update with Pics as the build progresses....A lot of the Idea's I will be using I saw in post on other builds.

Steve

battlestu · September 21, 2012, 12:38:55 PM

Sweet more Cubs

piker · September 21, 2012, 02:16:52 PM

Steve,

I'm not familiar with the Sig 1/5 scale Cub, but I like your choice over the Great Planes Cub as I believe the Sig Cubs are more accurate and generally much lighter.

I look forward to seeing the plane at TEMAC next summer.

Robert

Gregor77 · October 01, 2012, 08:04:53 AM

I was nice to see Glenns Yellow Sig kit, it flew great! He just needs to paint the landing gear! ha ha!

bfeist · October 01, 2012, 09:02:20 PM

Hey Steve I'm probably upgrading the motor in my revolver from a Rimfire .80 with ICE 75 to a Rimfire 1.20 with ICE 100.

If you're interested in a used Rimfire .80 and ICE 75 ESC let me know.

Ben

sts41 · October 22, 2012, 06:57:34 PM

Well It is Day 1, Oct 22, 2012...There is 180 days until I leave for Ontario...So it must be done by then.
I have checked that all the parts are in the box, and I have read the instructions for the 55th time.
I don't have the Motor or Landing gear yet, so I will start with the Stabilizers and Elevator. Yes I am deviating from the plans right from the start

that way, it will be much easier to place the blame later when something doesn't fit.

The build is pretty much divided into the 1) Fuselage 2) Wings 3) Horizontal and Vertical Stabilizer, Elevator, and Rudder. I will only be changing the order they are built in, not the way they are built.

Here are the starter pics....

Also, I have decided to leave it as a J3 cub instead of the Super... With the Yellow skin... I may need to stick with the P51 for Warbird day.

I have ordered the electronics for the strobes and lighting today...And found a nice circuit to imitate a strobe. If this is not bright enough...I may need to go with real strobes.

Other things I am pondering...And would like any input I can get to help with the decision.

5S or 6S Motor will be a RimFire .80. I can get the thrust about the same with either battery...
Pros for 5S is that I already have, and the current will be lower, even with the bigger prop.
Pros for 6S is higher RPM, a bit more thrust...But would need to buy 2 new batteries at $80 per.

That's it for tonight...Have a good one...

Steve

Michael · October 23, 2012, 09:05:03 AM

Quote from: sts41 on October 22, 2012, 06:57:34 PM

Other things I am pondering...And would like any input I can get to help with the decision.

5S or 6S Motor will be a RimFire .80. I can get the thrust about the same with either battery...
Pros for 5S is that I already have, and the current will be lower, even with the bigger prop.
Pros for 6S is higher RPM, a bit more thrust...But would need to buy 2 new batteries at $80 per.

Steve

Hi Steve.

Although a bigger battery will help balance the model (I needed to put the battery through the firewall into the cowl to balance), my model flew very well on 4S. In fact, I don't think I ever used full throttle. I used an E-Flite 46 equivalent motor.

5S should be plenty.

The most important thing to remember when flying a Cub at scale (slow) speeds, is to use rudder when turning.

flying saucer · October 23, 2012, 03:16:45 PM

Yes, you may even want to add rudder mixed in with your ailerons. Another thing I needed to do on mine was set everything to very high rates to get enough responsiveness.

sts41 · December 04, 2012, 09:11:39 AM

OK... Finished with the purchase of the new sled... Back to the build until the snow flies

I need to round off the edges of all the control surfaces. Does anyone have a neat rick to do a great job of this?

I will be trying a router bit for my Dremel, a hobby plane, and then just sandpaper....

But if anyone has a "You Just have to do it this way" trick.... Please let me know...Mostly looking for consistency.

Thanks All

Gregor77 · December 04, 2012, 09:28:59 AM

I used a great planes flat 1 foot sanding tool. But to do the edges, I was using a foam sanding block with two grits. One fine and one a bit rough. Once I cut it down to the right shape, I then just fine sand it. Seems to work fine.

battlestu · December 04, 2012, 09:40:24 AM

Steve i razor plane the edges down then sand

Papa · December 04, 2012, 10:16:40 AM

Take a block of pine. Drill a hole about 3/32" larger than the rounding you require. Cut the block on half so you have two half round grooves. Glue 150 grit in one and 220 in the other using carpenters glue and a dowel to clamp the sand paper. Use the plane to take some of the bulk off and finish with the sanding blocks. It goes very fast and you have an unbelievably uniform round edge.

Jack.

bfeist · December 04, 2012, 11:25:10 AM

Quote from: Papa on December 04, 2012, 10:16:40 AM
Take a block of pine. Drill a hole about 3/32" larger than the rounding you require. Cut the block on half so you have two half round grooves. Glue 150 grit in one and 220 in the other using carpenters glue and a dowel to clamp the sand paper. Use the plane to take some of the bulk off and finish with the sanding blocks. It goes very fast and you have an unbelievably uniform round edge.

Jack.

Excellent tip!
Don't forget that trailing edges should not be rounded. Squared off trailing edges are more aero.

Ben

piker · December 04, 2012, 01:41:19 PM

And nicely tappered to sharp edge is best (usually). The problem is, full scale have rounded TE's on their flying surfaces because of the tube contruction, although much smaller than the LE.

I always sand with a piece of 1x4x12 pine with a full sheet of 100 grit sand paper wrapped and stapled. I've used this for most of my sanding for 30+ years

For large raduis sanding (like a large LE) I shape generally with a hobby plane then sand smooth, while checking the profile. Smooth curvature transitions is the key. In other words, take the curve of the wing LE sheeting (for example) into the LE strip, then accelerate the curve around the LE. Starting by knocking off the corners to a 45 degree surface first, gets you closer to the shape you want and also provides a surface to view for consistancy along the length before finishing off the rounding (if that makes any sense at all).

Robert

sts41 · December 04, 2012, 01:47:58 PM

Some REALLY great Idea's... Will try them on some scrap wood and see what comes up.

Steve