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Old Oct 06, 2012, 04:12 PM
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Build Log
Sig 4*20 EP Build

Hi everyone.

Not relly doing a detailed build log here. Just thought I'd get a thread started to post some pics and have a place to ask questions as they arise.

This is actually my second kit. I have a Great Planes Electricub started. But after talking with guys at the flying field, they felt that wouldn't be a great candidate for my second plane. They recomended a Sig 4*. So this is what I have.

I've started the build and about 3 days into it. Not sure how many hours so far. But not many. Compared to the Cub, this plane is going together like a dream. The parts are great and they actually fit the plans. I"ve had no issues so far. I have the elevator and stabilizer completed and both wing halves very close to being able to join. I"m holding off on joining them until last minute. Just easier for me to have 2 small wings sitting rather than one large one.

Here is what I have to get it in the air.

Motor: Rimfire .10 350W 1250kv
ESC: Silver Series 45A
Battery: Lipo 3S 11.1V 3200mAh 25C (Not sure I can make this battery fit. May have to go a bit smaller)
Prop: 10-6
Servo: 4 Hitec HS-81

That about it for now. Hope to get it in the air before the snow flies.

Here are the pics so far.
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Old Oct 06, 2012, 07:07 PM
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Start of Fuselage

Got a little more done. I was able to get all the laminating of the fuselage parts done. Unfortunately have to give up for the weekend.

Still going smooth.
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Old Oct 07, 2012, 01:02 AM
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Joined Feb 2010
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pigcop,

Your 20 build is looking great, looking at the photos makes me miss mine. I built the kit right when it came out in 2010 as my second kit and I loved every minute of it. It flies like a proper sport plane and I was able to force it through ever maneuver I could think except flat spins (it is to stable for that ).

I posted my build pictures here and there is a main thread in the electric forum with much more info if you need to reference anything.

Keep up the good work, I am watching with interest!

Ethan
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Old Oct 07, 2012, 04:59 PM
Visitor from Reality
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http://www.rcgroups.com/forums/showt...245819&page=45 is a long running thread with much good input.

My build has, unfortunately, stagnated due to matters outside of aeromodelling - yes, they exist! Nothing bad, but all too 'interesting' in many ways.

There is plenty on that thread about Sig's unfortunate choice of battery bay and hatch, including my topside hatch and more aft battery placement alternations. In a nutshell, to swap a battery that is in a tight spot between firewall and wing LE former, the model must be held upside down, then flipped over when the new battery is connected and the model's ready to power up. Not a lot of fun...

Even so, my 2650mA 3S will be an overyly tight fit. 2300mA/3S drop in nicely. Mine's getting an E FLite 15 and around a 10 x 7 or 11 x 7 - have a 'fitting' UC that will offer more ground clearance to the prop.

D
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Last edited by Dereck; Oct 07, 2012 at 06:59 PM.
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Old Oct 08, 2012, 08:54 AM
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Ethan, I saw your video's on youtube. What happened to yours? It looked like a great flying machine. Even without landing gear. lol.

One question for you. If built to plans, do you think my power system is adequate? I'm pretty sure my motor will be ok, just think that the battery I have will be too heavy.

Dereck,
Thanks for the heads up on the thread. It'll give me something to read while at work.
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Old Oct 08, 2012, 10:07 AM
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Oops - my link is the same as Ethan's. Sorry, didn't mean to cause confustication in the thread.

As freds always look better with photos, here's my 'slightly altered' battery bay/hatch opening with two packs that could be used. Both are placed pretty much where they'll keep the CG happily located as per design.

D
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Old Oct 10, 2012, 01:31 PM
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More progress

Well, got a bit more done in the last couple of days. Havent had too much time to work on it. But its progressing pretty well. I've made a few rookie mistakes I think. I mis understood the directions and glued the fuselage doubler in a bit too low. Nothing seems unfixable without sanding though.

Other than that, I have the battery tray in. I chose to build it to plan as opposed to cutting hatch in the top. I just didn't feel comfortable doing that at this stage of my experience. Speaking of the battery, It appears that my big 3200mAh battery will fit in the designed bay. Just not sure if its going to be too heavy though. It feels like a ton. I was thinking of putting a former in the middle of the plane to act as a stop for the battery, as I was thinking of trying to put it as far back towards the CG as possible. The current set up doesn't seem like its very secure to me.

So as of date, I have the tail feathers all completed minus shaping and hinging, wings pretty much done, and fuselage very close to being completed. I have to say, while I don't have much experience in building, this kit is by far better than the GP Electrocub as far as parts fitting. This appears to be a very good kit for a first build.

Some more pics.
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Old Oct 10, 2012, 03:13 PM
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Quote:
Originally Posted by pigcop2 View Post

Other than that, I have the battery tray in. I chose to build it to plan as opposed to cutting hatch in the top. I just didn't feel comfortable doing that at this stage of my experience. Speaking of the battery, It appears that my big 3200mAh battery will fit in the designed bay. Just not sure if its going to be too heavy though. It feels like a ton. I was thinking of putting a former in the middle of the plane to act as a stop for the battery, as I was thinking of trying to put it as far back towards the CG as possible. The current set up doesn't seem like its very secure to me.

Some more pics.
Doing well, keep on going, it'll be fine. Sig kits are great. Seldom anything exciting about them, but rock solid and well engineered.

Watch that battery size for balance. The builders manual recomends 1800 - 2400 mA 3S packs, which for convenience these days settles nicely on the very common 3S 2200mA pack. That size will fit in the battery bay as per the kit, but puts the pack well ahead of the CG.

I must confess that my battery experience goes back into the dim mists of time, when the aim was to get a hefty pack over the CG and moving it a half-inch made the CG pack up and move real quick. Hence my 'slight alteration' to the kit's battery bay - which is a development of what I used on the Four Star 40 electrocution I did back around 1998.

With the kit battery bay, the easy way out would be to buy two or three identical packs, so you could swap packs and fly without having to worry over a shifting CG.

You could, with little extra effort, move the rudder and elevator servos to somewhere aft of the wing to help balance a forward battery pack. Early indications are that my model will balance with the battery as per my photos, so I've put the rudder and elevator servos in pretty much the kit position. In other models, I've put them aft of the wing with access through a bottom hatch in the fuselage - I have a serious allergy to servos hanging out in the breeze for some odd reason.

D
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Old Oct 10, 2012, 09:10 PM
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Quote:
Originally Posted by pigcop2 View Post
Ethan, I saw your video's on youtube. What happened to yours? It looked like a great flying machine. Even without landing gear. lol.

One question for you. If built to plans, do you think my power system is adequate? I'm pretty sure my motor will be ok, just think that the battery I have will be too heavy.
I sold it last year to some guy in Idaho who totaled it the next week when he tried putting a 2 pound camera under the wing I really miss it now. Someday I will build another one!

I built it to the plans but I used a .15 sized motor to get the vertical performance I wanted. I was a power freak at that time so I think your .10 350 watt motor will be plenty considering the designers used a much small Himax motor. Try and get a 1800-2200mah battery though or you will have to add tail weight. I used a 3S 2200mah battery and had to put about 2 oz. of lead in the tail.

The fuselage is looking good!

Ethan
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Old Oct 11, 2012, 09:27 AM
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D and Ethan. Thanks for the battery info and encouragement. I think 'll be looking to get a couple of 2200 packs.

Got the stringers for the turtle deck and top of the nose completed last night. Now to get the little things buttoned up and hopefully can start covering next week.

Thanks again
John
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Old Oct 24, 2012, 12:48 PM
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Well, my timeline wasnt quite what I had hoped for (wanted to be done by now). Still havent started covering, as I havent been able to work as much as I would like. I figured that I should probably do yard work and this other thing called work has gotten in the way. And Im trying to close on some property.

But Ive been slowly pushing on and have the wing 99% done, as is the fuselage. Tail surfaces are ready for covering.

I have some questions as far as radio/ motor set up. My plans do not show where the ESC goes. Any suggestions for this? I know it should go somewhere that it will get some airflow to stay cool. But other than that, no idea.

I plan on putting the reciever as far back as possible, depending on the CG. Any suggestions on mounting that?

Also what are the opinions on cutting hinges? I mean, my plans show that they should be cut after shaping the surface and covering, while the plans for my Cub say that they should be cut before shaping and covering. Opinions? I cut mine before shaping and covering. Seemed to me that it would be easier that way. Only thing I can see being a problem is locating the slots after covering.

Thats about it for now.

John
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Old Oct 25, 2012, 11:50 AM
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HI John
Hinges. I've always gone with trial-fitting even mylar hinges before covering. So, despite the instructions in my kit, I did it like I usually do. Found that the fuzzy covering on the kit hinges will only stand being pushed into the hinge slots once. Pull them out, put them back in, the fuzzy covering (there must be a more technical term - sorry!) peeled off the hinge plastic/mylar/whatever.

At which point, I tossed the kit hinges and used the ones I have a lot of in my building supplies. Suspect if you followed the instructions, the kit hinges will work fine though.

Receiver positioning. General groundswell these days suggests 2.4GHz receivers like to be well away from motors, ESCs, servos, wires and about anything else vaguely metallic. I'll probably put mine aft of the wing TE former, with a 'hatch' made from the balsa that fell out the first hole in the fuselage bottom sheet. Though I did toss the fuselage wire control runs in favour of my usual Sullivan 'Goldenrod' pushrods, which are all plastic.

Life does get in the way, doesn't it?

D
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Old Oct 26, 2012, 09:09 PM
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Progress

Thanks for the thoughts D.

I was thinking of putting the reciever as far back as I could. Depending on the CG.

I have some more progress. I have about a 95% mock up done. And I have weighed all the parts. It looks like Im going to come in uncovered right at 32oz. This is with the big 3200mAh battery.

Here are the latest.
John
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Old Oct 27, 2012, 02:59 PM
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progress

Got a bit more done today. Started to get the motor set up. Nothing is permanant yet.

The pics are what I came up with. I plan on using epoxy to glue the spacer to the firewall, and then epoxy the standoffs into the spacer.

Does anyone see any issues with doing it this way?

Thanks
John
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Old Oct 27, 2012, 03:28 PM
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Through bolt the motor mount and standoffs.
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