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-   -   4*Star 20 EP build (http://www.Wattflyer.com/forums/showthread.php?t=69868)

Scirocco14 02-19-2013 10:13 PM

4*Star 20 EP build
 
10 Attachment(s)
Hi folks!

I'm new to Wattflyer and electric planes in general. I've been flying nitro birds for 4 years now and my interest in electrics has been growing as I've seen the ease of use by some of my flying buddies.

I like to build, so I've decided to build a SIG 4*Star 20EP as my first electric build. Power will be an OS 10 size brushless motor and CC Ice Lite 50 ESC. Futaba S3115 servos for the control surfaces, and Monokote to cover it.

Enjoy the build pics! Any suggestions & comments along the way are appreciated.

Mark

Scirocco14 02-19-2013 10:16 PM

6 Attachment(s)
More pics! As you can see I'm a fan of 'repurposing' tools. I've found that sockets make great weights as well as 90 degree tools for holding ribs square, etc. :D

I've enjoyed building the newer SIG laser cut kits. I've built a couple of SIG "Craftsman Kits" (SIG Aerobipe that is getting electrocuted and a SIG Kadet Senior), and the new kits are just so much easier!

Mark

rcers 02-19-2013 11:29 PM

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It is an awesome plane, easy build and it flies wonderfully.

Here are my tips - top battery hatch is a MUST. The bottom hatch is just baffling - and from Sig (they are usually smart!).

The S3115 servos are plenty big - Fine for the rudder and elevator but the ailerons won't need that much.

Other than that - I love mine here is a pic.

Scirocco14 02-20-2013 12:03 AM

Quote:

Originally Posted by rcers (Post 901271)
It is an awesome plane, easy build and it flies wonderfully.

Here are my tips - top battery hatch is a MUST. The bottom hatch is just baffling - and from Sig (they are usually smart!).

The S3115 servos are plenty big - Fine for the rudder and elevator but the ailerons won't need that much.

Other than that - I love mine here is a pic.

Thanks for the tips!

Another thing that I plan on doing is ditching the cowl and building 'cheeks' like the bigger 4*Star planes. I have a 4*Star 40 and love it!

Mark

CrimzonRider 02-20-2013 12:05 AM

sub'd .......Good looking a/c build, I like that socket idea too.


cr

kyleservicetech 02-20-2013 12:48 AM

Quote:

Originally Posted by Scirocco14 (Post 901262)
Hi folks!

I'm new to Wattflyer and electric planes in general. I've been flying nitro birds for 4 years now and my interest in electrics has been growing as I've seen the ease of use by some of my flying buddies.

I like to build, so I've decided to build a SIG 4*Star 20EP as my first electric build. Power will be an OS 10 size brushless motor and CC Ice Lite 50 ESC. Futaba S3115 servos for the control surfaces, and Monokote to cover it.

Enjoy the build pics! Any suggestions & comments along the way are appreciated.

Mark

Yeah, I had the 4*40, and powered it with a very heavy Astroflight geared 40 motor with 22 Nicad cells. Even with this power system, that model flew very well. Finally gave it away some years back but it was still flying well.

It would have really flew even better with the modern brushless motors and the much lighter weight LiPo or A123 cells.

One thing you might check out is one of those computer programs such as www.motocalc.com, free for 30 days, then #39. IMHO, worth every penny if you want to try different props, batteries and so on with your model.

Dereck 02-20-2013 03:12 AM

Good model Mark. I built mine just in time for 'building season' weather to hit Chicagoland, so it's still hanging on the shop wall. Mine's got an E Flite Power 15 lump, which on 3s around 2200mA and a 10 x 7 should offer 'adequate' power for starters.

My main alterations were changing to a topside battery hatch and mounting the aileron servos horizontally inside the wings.

Had a Four Star 40E for eleven years, though Maxim geared brushless inrunner motors were invented just before I got into bigger electrics. 600W out of a 20 cell nicad pack that weighed around 42 ounces. But no-one ever suggested it was boring to watch ;). Bet the new baby will be just as much fun.

My Four Star 40 had a full cowl originally. Love the 20 moulded cowling! My new baby is covered in SoLite.

Dereck

Scirocco14 02-20-2013 03:59 AM

Quote:

Originally Posted by Dereck (Post 901315)
Good model Mark. I built mine just in time for 'building season' weather to hit Chicagoland, so it's still hanging on the shop wall. Mine's got an E Flite Power 15 lump, which on 3s around 2200mA and a 10 x 7 should offer 'adequate' power for starters.

My main alterations were changing to a topside battery hatch and mounting the aileron servos horizontally inside the wings.

Had a Four Star 40E for eleven years, though Maxim geared brushless inrunner motors were invented just before I got into bigger electrics. 600W out of a 20 cell nicad pack that weighed around 42 ounces. But no-one ever suggested it was boring to watch ;). Bet the new baby will be just as much fun.

My Four Star 40 had a full cowl originally. Love the 20 moulded cowling! My new baby is covered in SoLite.

Dereck

Thanks for the ideas, Dereck. :D

Your Four Star 40 had a full cowl? Was it an ARF or did you build it with a cowl? I kind of like the looks of the cheeks on the 4*Stars.

Mark

Al_M 02-20-2013 12:34 PM

Don't ever ask Dereck if it was an arf again. That term will give him fits!

Dereck 02-20-2013 03:44 PM

Quote:

Originally Posted by Scirocco14 (Post 901319)
Thanks for the ideas, Dereck. :D

Your Four Star 40 had a full cowl? Was it an ARF or did you build it with a cowl? I kind of like the looks of the cheeks on the 4*Stars.

Mark

I built mine back in 1998 - not even sure if Sig BARF'ed (Bought Almost Ready to Fix - Olde English FLA [four letter abbreviation] ) back then.

I electrocuted the kit for a magazine article on converting it to quiet power. Even though the motor was the hottest electric drivetrain on the US market back then - a geared MaxCim 'inrunner' with five extra thin wires to control the motor speed - I built a full cowling around the motor, based on the remains of the liteply fuselage sides ahead of the firewall and my balsa scrap box. The aim was to firstly make it look a little different and possibly have less front end drag, secondly to create directed cooling into the cowl and around the motor.

The original cheeks were the easy way around fitting a wide range of slimers, plus they're much easier to both 'kit' and 'build' than a cowling - moulded cowls around slimers are a lot of fun when it comes to cutting out holes for cylinders, silencers and so on. As I'm sure you know, coming from oily models ;) Save you wondering - I flew oily RC for a fair while before going all electric. Spousal Unit's dislike of how I smelled after flying sessions had a large part in my switching over...

Why Sig went with that bottom battery hatch on the 20E escapes me, other than it's cheap. Nearly every electrocuted 4* I've seen or heard of has had some kind of top hatch, as have the BTE Venture 60 electrics. It's not only ease of battery swapping with a top hatch, their forward underside hatch tends to make the model nose-heavy and also demands you stick with one size of battery that fits in there. If you used different sizes/weights of pack, its forward location could mess up the model's CG somewhat

We can safely ignore a clubmate of mine some time back who built a Four Star 40 completely stock, lashed a geared Astro 25 cobalt into the glow engine mount with a hose clamp and whose 'battery hatch' involved taking the wing off, stuffing a foam wrapped 16 cell nicad battery into the hole where the fuel tank went through and bolting the wing back on... It flew pretty good too.

If you want to revert to the historical 4* side cheeks, you'll need to mount the motor further forwards to maintain the traditional shape - outrunners are shorter than slimey lumps.

Keep on gluing

D

Dereck 02-20-2013 09:07 PM

Somehow duplicated...

Dereck 02-20-2013 09:15 PM

2 Attachment(s)
Okay, let's add a little colour as Chicago waddles along with temps well under 20 degrees and enough wind to make hypothermia a popular option :(

Here's my battery hatch. It's a snip as the top deck is of parallel section for its length - the 4*40 front top deck tapers in height towards the firewall. All you need do is build the model pretty much fully, bar the top decking ahead of the cockpit. Guesstimate the CG position by putting it all together with the expensive bits in place and trying out the battery.

Now make the hatch an inch or so longer than your longest battery. Mine has a former at either end of the hatch, one in the middle and an 1/8" square top longeron in the middle of the formers, which sit on light-ish 1/16" balsa with its grain across the fuselage. You can make the formers by using one of the kit's top deck formers as a pattern, adjusting for the hatch bottom sheeting, of course.

Ply tab at the front, rare earth magnet in the former at the rear of the hatch and front of the fuselage top decking aft of the hatch. The top deck sheeting came out of the kit box, the 1/8" for the extra formers came out of my well-stocked scrap box.

Afterthoughts? I should have put the fuselage servos aft of the former at the wing TE and scooted the battery forwards a little. That would have allowed me to easily use a 2650ma 3S LiPo I have, as well as my somewhat shorter 2200's. The servos are right aft in the overwing bay, along with the RX and it's a little scrunched in there, though it will work.

I also tossed the kit wire fuselage control pushrods for my usual Sullivan 'Goldenrods'. The aileron servos are mounted inside the wing, not hanging out in the slipstream like the kit mountings. Both can be attached to my pet likes and dislikes over suchlike. ALtering the servo mounts and the battery location and hatch probably took me longer than assembling the rest of the kit!

If you're wondering why the cowling is white, I was still trying to find a small can of matching red spray paint. At the time, little did I know that Chicago's political IAms had, some years ago, banned the sale of spray can paint in the windy city. Which means that I had to drive 40-odd miles to buy a can of paint, as do the street trash that continously spray paint over wherever they fancy in Chicago...

Hope that helps

D

Scirocco14 02-20-2013 09:47 PM

Thanks for the ideas, Dereck. I'm glad I started this build thread! :D

Mark

tobydogs 02-20-2013 10:40 PM

looking good mark! count another as subscribed and looking foward to seeing your build thru....[popcorn]

Scirocco14 02-21-2013 01:33 AM

3 Attachment(s)
Got some more gluing done today. Firewall glued in, as well as the battery tray. I am going to add some lightweight tri-stock behind the firewall to help reinforce it.

Trial fitted the vertical fin and horizontal stabilizer.

I work almost exclusively with aliphatic wood glue, so there's a lot of drying time in between gluing. ;)

kyleservicetech 02-21-2013 01:51 AM

Quote:

Originally Posted by Scirocco14 (Post 901395)

I work almost exclusively with aliphatic wood glue, so there's a lot of drying time in between gluing. ;)


Yeah, probably 95% of my model gluing is also done with aliphatic or Titebond yellow wood glue. This stuff allows time to make certain everything is straight, and is STRONG. Plus if you need to sand the glue joint, this stuff sands like balsa wood. Several years ago I did some tests with glue joint weights using a gram scale, comparing CA against Titebond. After the Titebond has cured for 24 hours, the Titebond is actually a little bit lighter than the CA joint. Apparently the liquid in Titebond evaporates leaving only the adhesive itself. The CA type glues, everything you put on, stays in the glue joint.

I've got several bottles of thin and thick CA, several bottles of various types of epoxy, but still that yellow glue wins out for me.

Scirocco14 02-21-2013 02:00 AM

I can't really stand the fumes of CA and I'm not really in a hurry when I build so Aliphatic wood glues are fine. I've used Elmer's wood glue, Titebond, SIGBond, and like them all. You're right, it gives you a little time to assemble and check the parts when you're gluing. Also it's CHEAP!

I use epoxy in high strength applications and when laminating. The epoxy doesn't warp the wood like wood glues can when laminating. The key for me is to use a credit card to spread the epoxy VERY thin, removing almost all of the epoxy. Then when clamped together, very little oozes out and the resulting piece is very light. Since epoxy isn't water-based, it doesn't warp the pieces as easily.

CA? I use it on hinges and for repairs when I cannot get a clamp on it or is in an inaccessible spot.

Mark

Dereck 02-21-2013 09:01 PM

Mark
Idle thought looking at your photos. If you're going with a top hatch, I made a few changes like losing the kit's battery tray and much of that top fuselage sheeting - the flat part under the curved top - to fit my battery tray just above the wing seating. Being a tightwad, the kit battery tray kept its job, but moved house some.

Have a think about where you want to put stuff like battery, servos and RX before you get too far in. Unfortunately, as I was just building this kit for the fun of it, I didn't bother keeping many of my building shots.

However, some of them and a bunch of other good stuff from the World Famous 'FSOC' (Four Star Owners Club) are on the opposition at:

http://www.rcgroups.com/forums/showt...t=four+star+20

http://www.rcgroups.com/forums/showt...t=four+star+20

D

Scirocco14 02-22-2013 12:34 AM

Hi Dereck,

I'm going to build it per the plans, my batteries fit fine in the OEM battery space. I might add a tray extension behind the former, and build a small box there to retain the battery.

I appreciate your advice though!

Mark

rcers 02-22-2013 12:43 AM

Well mine is WAY nose heavy in the stock location. Thus my recommendation for a top hatch.

:)

Mike

Scirocco14 02-22-2013 12:57 AM

Quote:

Originally Posted by rcers (Post 901508)
Well mine is WAY nose heavy in the stock location. Thus my recommendation for a top hatch.

:)

Mike

Hence why I'm going to try and extend the stock battery tray past the former. There's room for it about the wing. If it doesn't work, then I'll be making a top hatch. :D

Mark

rcers 02-22-2013 01:26 AM

Well understood. You asked for advice so I gave some.

Every time you flip it over to change the batteries you will remember me and think I should have listened to that guy.

Mark my words. :)

The bottom hatch was a real doink by SIG.

Scirocco14 02-22-2013 01:44 AM

Quote:

Originally Posted by rcers (Post 901519)
Well understood. You asked for advice so I gave some.

Every time you flip it over to change the batteries you will remember me and think I should have listened to that guy.

Mark my words. :)

The bottom hatch was a real doink by SIG.

I'll put your name on the hatch, just in case I forget. ;)

Mark

Henry Sistrunk 02-22-2013 02:00 PM

Quote:

Originally Posted by rcers (Post 901519)
Well understood. You asked for advice so I gave some.

Every time you flip it over to change the batteries you will remember me and think I should have listened to that guy.

Mark my words. :)

The bottom hatch was a real doink by SIG.

Another vote for a hatch on top. Hatches on the bottom are a PITA. Just my 2 cents worth.
Henry

Scirocco14 02-22-2013 02:46 PM

1 Attachment(s)
I appreciate the advice guys. I'm just hard-headed and am going to build it per the plans. I like the clean look of the fusealage w/o the hatch on top. If it doesn't work out, I can always go in later and install the hatch.

When I'm at the field, i always bring one of these stands to assemble my planes, and it'll make changing the battery less painful...



Nose-heavy? Hah...I can build 'em tail heavy with the best of them. :D

Mark


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