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Back to the Darkside….. Where’re the cookies?!?

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Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Mon Apr 27, 2015 12:47 am

Well, on to the next thing in the queue.  Wanting something a little larger, I decided to go ahead and build the SIG Akromaster kit that I bought 35 years ago.  I was originally planning on building it with a Cox Medallion .15 in it, but decided I needed something a little quieter.  So, I sunk to committing Elektrickery.  I had an electric motor that would do, so electric it is.  I’m not going to put a whole lot of time into this one either, as I expect to be awfully hard on this one, too.  

The first thing I did was cut out a new fuselage.  I extended the tail by two inches, as the motor and battery would move the c.g. forward.  I clamped the kit fuselage to the 3/8x 3” balsa sheet and traced the outline in pencil.  Then moved things and traced again.  Then changed my mind and traced again.  I ended up raising the top of the fuse by ½” to make a little more room for the battery box.  You can see the pencil marks as I changed my mind.  You can also see the cutout for the battery box.







And the ply doublers for the front of the plane.




I built a battery box from 1/16” ply top and bottom, and a 1/8” lite ply side wall.







Here’re the doublers rough cut and the battery box sitting in place.




Jump forward ahead and the doublers and battery box are glued in place.  






I glued balsa blocks on and shaped them into a not too hideous shape behind the firewall, and in from of the firewall to provide support for the firewall fore and aft.



Jump ahead again and the wing has been built with the exception of center sheeting, and the tail surfaces are finished.  Here everything’s fit together while I take a break.








To be continued later,
The Not Too Hideous Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  getback on Mon Apr 27, 2015 8:17 am

Well Mark You have done it again LOOKS Good !! I have one of those to build as soon as I get through with the BClown , did the wing build go smooth or maybe have some pointers ? Eric
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Mon Apr 27, 2015 4:10 pm

Pointers? Yeah, don't use a 35 year old kit. After 35 years in the box, the trailing edge stock was very warped. I tried soaking it and then clamping it to dry out, but that didn't remove all of the warp. Most of it, but not all. Also, the wing rib sheets weren't stamped well, so I spent a good bit of time sanding the back to get the parts to pop out.

For building the wing, the kit includes fixtures to hold the leading edge and trailing edge in place for gluing. The ones in my kit were terrible die crushed. They were useless. So, I went back to the old fashioned method of aligning the tip ribs, and working my way along gluing ribs in towards the center.

Other than that, it's a straight forward kit. At least, I assume so. I didn't build it per the plans, naturally. I have a new Akromaster kit that I bought last year, and still plan on building for the Medallion .15, so it should go together much faster.

The Warped Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  pkrankow on Mon Apr 27, 2015 6:07 pm

batjac wrote:Pointers?  Yeah, don't use a 35 year old kit.  After 35 years in the box, the trailing edge stock was very warped.  I tried soaking it and then clamping it to dry out, but that didn't remove all of the warp.  Most of it, but not all.  Also, the wing rib sheets weren't stamped well, so I spent a good bit of time sanding the back to get the parts to pop out.

For building the wing, the kit includes fixtures to hold the leading edge and trailing edge in place for gluing.  The ones in my kit were terrible die crushed.  They were useless.  So, I went back to the old fashioned method of aligning the tip ribs, and working my way along gluing ribs in towards the center.

Other than that, it's a straight forward kit.  At least, I assume so.  I didn't build it per the plans, naturally.  I have a new Akromaster kit that I bought last year, and still plan on building for the Medallion .15, so it should go together much faster.

The Warped Mark

Maybe you should have cut yourself a new "kit" using the parts as patterns!
Phil
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Mon Apr 27, 2015 6:54 pm

pkrankow wrote:

Maybe you should have cut yourself a new "kit" using the parts as patterns!
Phil

Phil, I went to the local hobby shop to see if they had the right size t.e. material, but no good. I didn't have any in my woodpile either. For the Akromaster, SIG used non-standard sizes for the leading and trailing edge stock. I did have to cut some new ribs for the wing, as I made the longer wing version of the plane.

Eric, you do know about making the wing longer, don't you?

The No Good Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  NEW222 on Mon Apr 27, 2015 7:35 pm

Nice build. Partial to the Acromaster as well. Got me a kit here too. Bought it about 15 years ago. Used it for templates, scratched one out, got out of flying for a bit, sold it 2 years ago, and am now regretting it. Should have kept it, but at least I have the original to use again as templates. Anyways, I will be watching this one.
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Man! This thing is a PIG!

Post  batjac on Sat May 02, 2015 5:27 pm

I don’t know if I built this too heavy, or if I’m just used to building models with a 6 or 7 ounce finished weight, but this thing feels just plain porky.  It’s ready for cover, and it already weighs 10 ounces bare bones.  I don’t know how it’s gonna fly…



The Uncertain Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  Cribbs74 on Sat May 02, 2015 5:50 pm

Not to worry Mark!

A TD can pull 9-10oz without issue. I am sure a .15 can pull 15oz or more easily.

Now.... I see you have chosen electric, that will add some weight quick. Can you muffle the medallion .15?

Ron

Edit: Mark poking around the internet I see other Akromasters that are close to 20oz and still fly well...
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  getback on Sun May 03, 2015 7:57 am

No Mark I no nothing about making the wing longer ? mine is 34" at 250sq. is that not enough ?
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Sun May 03, 2015 2:10 pm

Ron,  thanks for poking around the web.  Now I don't feel too bad.  I can probably come in close to 20.  Since it's electric, I can skimp on the fuselage finishing and paint.  It just needs to be enough to protect the balsa, not to fuel-proof the darn thing.  I guess I just need to get used to building moderate sized models. By the way, I do have another kit that I plan to build with a muffled Medallion .15 engine. Maybe I'll move that to the head of the queue once I finish this one, as the building peculiarities and new ideas are fresh in my mind.


Eric, the standard wing is 34" at 250 sq.in.  That's quite enough to fly well, as probably thousands of these have been built over the years at 34".  But, you can get a free 4" extension of the wingspan for about 280 sq.in. wing area.  In the instructions for building the Akromaster wing, they tell you to take a razor saw and cut off 1" from each end of the leading and trailing edge stock.  If you leave that in and make up two extra R3 tip ribs and two extra R1 ribs, you get some free wing.  You also have to make up a new bellcrank plate out of ply, but that's no biggie.  You only really need one extra R1 rib, but I made two.  One out of 1/16" to match the existing one, and one out of 1/4" for a center rib.  I like to have the center rib thickness close to the fuselage thickness to make it more solid in the center.  I had to get a little creative with the bellcrank location, but again it was no biggie.  If you do a search on Stunt Hangar you'll get all the info on the wing stretch.

The
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Fri May 22, 2015 2:48 am

Well, I had a little time to get back to the plane.  I started covering it with red and white Monokote in the traditional Batjac Aeroworks™ color scheme.  I got the bottom of the wing and the wing tips covered before I realized I did something wrong. I have been known to finish the plane, and then realize that I forgot to add the tip weight before closing out the wing.  So I quickly added this note:




Then I decided I might not notice the note before I started covering the wing again, so I made a bigger note.  




The instructions said to use a half ounce of weight, and that works out to three nickels.




The Forgetful Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  getback on Fri May 22, 2015 8:46 am

Now that's a 15 cent plane for sure , Mark I looked over the instructions and there is nothing there about the wing stretch ? Thanks for the info I take a look a SH and just see I will probably stay with the planes for now though // as long as it flys I will bee excited Very Happy  Heck I am already behind on winter building lol! Edit ; well I reread your post Sorry I misunderstood Embarassed I get it now man I am sloooow DAMMIT!


Last edited by getback on Fri May 22, 2015 8:50 am; edited 1 time in total (Reason for editing : to fix embarrasment)
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  batjac on Sat May 30, 2015 8:01 pm

Well, it’s not my neatest covering job, but it should do.  Standard covering scheme and all.  Easy to repair when the plane breaks.  The only things left to do are make up a pushrod and solder up the speed controller connections.  









The Unfinished Mark
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  Ken Cook on Sat May 30, 2015 8:08 pm

Mark, I think it looks great. Ken
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  rogermharris on Sat May 30, 2015 8:14 pm

Looks great from here!
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  Cribbs74 on Sat May 30, 2015 8:14 pm

Mark,

Hands down the cleanest electric installation I have ever seen on a profile. Pat yourself on the back for a job well done.

Let us know how that thing flys!

Ron
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  gcb on Sat May 30, 2015 8:30 pm

I built my last Akromaster using the increased wingspan. I think it is worth the effort. Power is a TT .10.
I would suggest for ANY kit that uses isometric instructions that you trace the parts on back of the instruction sheet so you can recreate parts if necessary.

Enjoy your Akro.

George
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Re: Back to the Darkside….. Where’re the cookies?!?

Post  getback on Sun May 31, 2015 6:41 am

That it very clean and slick with the battery installment , Does she balance out good Mark ? Good Job Man !! Very Happy Clapping
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Re: Back to the Darkside….. Where’re the cookies?!?

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