Author Topic: Sig Magnum (Read 13903 times)

MarcusCordeiro · « **on:** September 04, 2012, 02:32:25 PM »

Hi all

Got my Magnum today!!

Have always wanted to build one.
Will power it with one ST¨60.
Wondered if anyone had a tip or two for building it.
25 years in a box and still in great condition.
One thing for sure, replace the bellcrank for one 4" CF.
It's the double cored wings.
Any help will be welcomed.

Thanks

Marcus

Balsa Butcher · « **Reply #1 on:** September 04, 2012, 05:10:45 PM »

As far as the double cored wings go...cut a strip of foam (can be from the wing cradle or another project) and insert and glue it inside the rear cut-out, approximately centered. This will create a triple cored wing. It will maintain its airfoil shape better than a double cored wing as those wings tend to flatten out over time.

MarcusCordeiro · « **Reply #2 on:** September 05, 2012, 06:49:37 AM »

Thanks guys. Yes, the wings... I'll cut it from the core that comes with it. That's good advice.
Anyway, the kit seems to be just like a regular building.
My concern is sheeting the wings. I'm not really sure about the glue..
What do you guys use for that?

Marcus

john e. holliday · « **Reply #3 on:** September 05, 2012, 08:51:01 AM »

Remember to leave the cores in place while sheeting the panels. I would use the old tried and true epoxy method. Slow cure of course. Spread the epoxy as thin as you can with the credit card on the balsa sheets. When you think it is thin enough go over it again. Remember to have a flat surface to put the cradles on and most of all a flat plank on top with lots of weights. Let set for more than 24 hour curing time.

MarcusCordeiro · « **Reply #4 on:** September 06, 2012, 09:35:30 AM »

Thanks John

Epoxi could be an option. The instruction booklet says Sig Core-Bond, but it's 25 years old...

I thought by now there could be something more up to date.
I could thin the epoxi using some alcohol and spread it with a brush, couldn't I?
That way I could keep it thin and save some weight.
I'll check what else I have available before I make my mind.

Marcus

Balsa Butcher · « **Reply #5 on:** September 06, 2012, 03:07:51 PM »

If you can find some Z-Poxy, that is the epoxy of choice for most. It is a finising resin as opposed to epoxy glue. Much thinner and can be spread out very thin. If you go to the tips section of Heman Lee's "Aeromaniacs" site you will find a link to a tutorial that Bob Hunt did on sheeting foam wings. I think you will find it very helpful.

Bill Little · « **Reply #6 on:** September 06, 2012, 03:33:55 PM »

Quote from: Balsa Butcher on September 06, 2012, 03:07:51 PM

If you can find some Z-Poxy, that is the epoxy of choice for most. It is a finising resin as opposed to epoxy glue. Much thinner and can be spread out very thin. If you go to the tips section of Heman Lee's "Aeromaniacs" site you will find a link to a tutorial that Bob Hunt did on sheeting foam wings. I think you will find it very helpful.

HI Pete,

Z-Poxy also comes in a 30 min. epoxy. I made a mistake by buying the epoxy last time I needed some "Z-Poxy". Same carton, bottles and all as far as I could tell. (I wanted the finishing resin!)

BIG Bear
RNMM/AMM

MarcusCordeiro · « **Reply #7 on:** September 06, 2012, 03:52:33 PM »

Thanks people.
That's really good advice

Marcus

Jim Oliver · « **Reply #8 on:** September 12, 2012, 09:49:33 PM »

Marcus,

I would suggest that you carefully check the cores, bith wing and stab, to make sure that the cores are identical. When I built my first Magnum, I found that the wing cores were different thickness.

I didn't discover the problem until after the cores were sheeted and ready to join. I was NOT pleased

Jim

MarcusCordeiro · « **Reply #9 on:** September 13, 2012, 08:38:22 PM »

Quote from: Jim Oliver on September 12, 2012, 09:49:33 PM

Marcus,

I would suggest that you carefully check the cores, bith wing and stab, to make sure that the cores are identical. When I built my first Magnum, I found that the wing cores were different thickness.

I didn't discover the problem until after the cores were sheeted and ready to join. I was NOT pleased

Jim

Thanks, that didn't cross my mind.
First thing tomorrow morning.
Just checked and all the parts are there.
Now, a little question popped in there, if I replace the stock 3" bellcrank for one 4", should I replace anything else or can I still use the stock horns?

Marcus

john e. holliday · « **Reply #10 on:** September 14, 2012, 08:27:58 AM »

Use a little common sense here. If you change one component, it will change the movements of the other components.

MarcusCordeiro · « **Reply #11 on:** September 14, 2012, 10:34:15 AM »

Quote from: john e. holliday on September 14, 2012, 08:27:58 AM

Use a little common sense here. If you change one component, it will change the movements of the other components.

That's a sure thing John.
What I wanted to figure out was whether or not that would be a smart move.
I've been thinking about Tom Morris controls for this model.
Maybe that would be the smartest choice.

Marcus

Bill Little · « **Reply #12 on:** September 14, 2012, 10:37:32 AM »

Quote from: MarcusCordeiro on September 14, 2012, 10:34:15 AM

That's a sure thing John.
What I wanted to figure out was whether or not that would be a smart move.
I've been thinking about Tom Morris controls for this model.
Maybe that would be the smartest choice.

Marcus

HI Marcus,

I would definitely strongly consider the Tom Morris controls. Tell him want you need it for and he can give you a proper set up.

BIG Bear
RNMM/AMM

Pat · « **Reply #13 on:** September 17, 2012, 08:07:05 PM »

Marcus,

I am building a Magnum right now. I sheeted my wings with water based contact cement and it worked like a charm. I used a foam brush so it made it easy to strip any excess cement off. I used a 3 inch bell crank with carbon fiber push rods and ball ends.

Pat

Rafael Gonzalez · « **Reply #14 on:** September 18, 2012, 08:45:02 AM »

Quote from: MarcusCordeiro on September 05, 2012, 06:49:37 AM

Thanks guys. Yes, the wings... I'll cut it from the core that comes with it. That's good advice.
Anyway, the kit seems to be just like a regular building.
My concern is sheeting the wings. I'm not really sure about the glue..
What do you guys use for that?

Marcus

If you have not done the coring, the best available and lightest is Gorilla glue. Its a Poly glue that foams as it cures. It covers any valley or pore and forms a completely solid surface. Do all your prerequisite prep for the sheeting and when ready, spray the foam with a mist of water(Very, very light) wipe the foam with a dry cloth or towel just to make sure that there are no water spits from the mist. Poly uses moisture (humidity) as a catalyst. The wings will dry and be humid by the time you do the next step.

Get a squeegee and squeegee the gorilla glue on the skins to the point that there is a semi-flat shine on the balsa. Do the other skin and place on wing using the cradle. let it sit for 24-48 hrs. The glue is sandable much better than epoxy and 3 times lighter!!!

john e. holliday · « **Reply #15 on:** September 18, 2012, 09:11:39 AM »

Make sure you have something in the cradle to protect it. The Gorilla Glue will find every little pin hole and crack in the balsa sheeting no matter how thin you put it on the balsa sheet. It comes alive when the moistened foam comes in contact and starts growing. Also leave the cores in the foam wing as you will need to put lots of weights on the flat boards to keep the sheeting in contact with the foam until it cures. 24 hours minimum before removing the weights. Goes the same if you use epoxy. Wear goves and have plenty of rags as both glues are messy if you are like me. Remember the flat surface determines how straight your wing will be when the glue is cured.

MarcusCordeiro · « **Reply #16 on:** September 18, 2012, 10:34:41 AM »

Thanks guys.
Every word of advice was very helpful, and now I have options to consider.
I'll start building in a couple of weeks, so I have some time to make up my mind.
In the mean time, I'll see about the controls.
I've checked the vendor's corner and Control Line Central seems to have Tom Morris's.
The 3" bellcrank looks so tiny for the ST 60...

Pat, mind if I ask what motor you're using for yours?

I'll keep you guys updated.

Marcus

Rafael Gonzalez · « **Reply #17 on:** September 18, 2012, 11:36:15 AM »

Quote from: john e. holliday on September 18, 2012, 09:11:39 AM

Make sure you have something in the cradle to protect it. The Gorilla Glue will find every little pin hole and crack in the balsa sheeting no matter how thin you put it on the balsa sheet. It comes alive when the moistened foam comes in contact and starts growing. Also leave the cores in the foam wing as you will need to put lots of weights on the flat boards to keep the sheeting in contact with the foam until it cures. 24 hours minimum before removing the weights. Goes the same if you use epoxy. Wear goves and have plenty of rags as both glues are messy if you are like me. Remember the flat surface determines how straight your wing will be when the glue is cured.

That's right Bill!

I forgot, I use wax paper in between the cores and the wings!!! And yes lots of weight! And a straight and trued surface...

Pat · « **Reply #18 on:** September 19, 2012, 08:02:28 AM »

Marcus,

I am leaning tword the evolution .61, this is a really nice engine that is basically the physical size of a .46 or so. If I don't use that I will be going with a Super Tiger G 51, that has been worked over by Randy smith. This will be the more expensive option I am sure.

Pat

MarcusCordeiro · « **Reply #19 on:** September 19, 2012, 10:14:37 AM »

Quote from: Pat on September 19, 2012, 08:02:28 AM

Marcus,

I am leaning tword the evolution .61, this is a really nice engine that is basically the physical size of a .46 or so. If I don't use that I will be going with a Super Tiger G 51, that has been worked over by Randy smith. This will be the more expensive option I am sure.

Pat

Pat

I've heard good comments on the Evolution, though never had one.
I have a big stunter here, about 67 ounces, and it's hauled by one ST 51.
Very powerful and easy to handle. Mine is stock, so one by Randy...

Marcus

Pat · « **Reply #20 on:** September 19, 2012, 11:17:21 AM »

I plan on getting the plane almost complete, and then weighing it before making my final decision. But I do like the idea of the Evo .61. As a drag racer I subscribe to the "you can never have to much power" theory...

Bill Little · « **Reply #21 on:** September 19, 2012, 11:58:18 AM »

Hi Pat,

I think either engine would be very close in performance. The ST .51 is a strong stunt engine, especially set up correctly. I have a NIB Evo .60 that I will test and probably fly in the "redone" SV-11.

Bill

Pat · « **Reply #22 on:** September 19, 2012, 08:10:01 PM »

Bill,
It all goes back to the "No replacement for displacement" thought!

MarcusCordeiro · « **Reply #23 on:** October 16, 2012, 07:02:24 AM »

Well

I have started...

Airacobra · « **Reply #24 on:** October 16, 2012, 06:00:24 PM »

There is fellow in our club that has been using one of the Evo .61. The engine is in a Time Machine. Probably not the lightest plane as he will attest, but the Evo has no problem hauling that plane through the air. It seems to run a bit smoother than the ST 60 and starts very easy. Seems to me there is no way you could go wrong with the Evo. It has me wanting one as I write this.

MarcusCordeiro · « **Reply #25 on:** October 16, 2012, 06:55:02 PM »

Quote from: Airacobra on October 16, 2012, 06:00:24 PM

There is fellow in our club that has been using one of the Evo .61. The engine is in a Time Machine. Probably not the lightest plane as he will attest, but the Evo has no problem hauling that plane through the air. It seems to run a bit smoother than the ST 60 and starts very easy. Seems to me there is no way you could go wrong with the Evo. It has me wanting one as I write this.

I agree totally. heard good results from the people who have been using it.

Marcus

MarcusCordeiro · « **Reply #26 on:** October 21, 2012, 06:04:51 PM »

I'm not a fast builder, but there's been a little progress.

Marcus

MarcusCordeiro · « **Reply #27 on:** October 23, 2012, 07:00:49 PM »

Got the elevators almost finished.
While I wait for thr Z-POXY resin to arrive, let's advance whatever I can

Marcus

MarcusCordeiro · « **Reply #28 on:** October 26, 2012, 08:45:09 PM »

The flaps. There've been numerous comments about sheeting those flaps...

Marcus

RC Storick · « **Reply #29 on:** October 26, 2012, 10:04:00 PM »

Heck I am not a fast builder anymore

billbyles · « **Reply #30 on:** October 30, 2012, 07:08:41 PM »

Quote from: Robert Storick on October 26, 2012, 10:04:00 PM

Heck I am not a fast builder anymore

Riiiigghhht, Robert...since you build at the speed of heat I'm surprised that you haven't found a way to spray on the finish while the wing is still in the jig!

MarcusCordeiro · « **Reply #31 on:** October 30, 2012, 07:57:00 PM »

A little more done...
Hope to have that nose done by the end of the weekend, there's a lot of carving to do

Marcus

MarcusCordeiro · « **Reply #32 on:** November 01, 2012, 06:43:49 PM »

I'll have to work on the top block and think I'll go with a cockpit... Never liked it, but after seeing Derek's thread, I got motivated to do one.
I think a cockpit weakens the area 'cause you cut the top block.
Gotta find a nice pilot...

Marcus

MarcusCordeiro · « **Reply #33 on:** November 04, 2012, 05:19:03 PM »

I'm a man of my word...

Marcus

Avaiojet · « **Reply #34 on:** November 06, 2012, 09:52:36 PM »

Marcus,

Nice build so far. Looks like you know what you're doing.

Did you sheet those wings yet?

Charles

MarcusCordeiro · « **Reply #35 on:** November 07, 2012, 03:11:29 AM »

Charles

I'm about to. My local model shop got the resin, but it's not the ZPOXY, it's Brodak's, so I needed to check if it would be ok to use it. It is, so next week I.ll be working on all the sheeting, there's the stab too, which I'll do first. Gotta finish the fuselage this week..

Marcus

RandySmith · « **Reply #36 on:** November 07, 2012, 11:50:36 PM »

Quote from: Ty Marcucci on September 04, 2012, 03:25:27 PM

Foam wings? Wow. The one I built in 1974 was all balsa and at the time the biggest plane I had ever built. Keep it light.

They made an all balsa kit??? I would like to find one of those

Randy

Brett Buck · « **Reply #37 on:** November 09, 2012, 07:22:53 PM »

Quote from: RandySmith on November 07, 2012, 11:50:36 PM

They made an all balsa kit??? I would like to find one of those

Randy

I think Ty is confusing this with something else, I think the Magnum was first produced in the mid-80s, not 1974.

Brett

MarcusCordeiro · « **Reply #38 on:** November 10, 2012, 05:10:55 AM »

Quote from: Brett Buck on November 09, 2012, 07:22:53 PM

I think Ty is confusing this with something else, I think the Magnum was first produced in the mid-80s, not 1974.

Brett

It was released in 1986, I have the FM issue...

Marcus

MarcusCordeiro · « **Reply #39 on:** November 21, 2012, 01:47:18 PM »

I got the bottom fuse sheeting done. The cowl will get an exhaust for the hot air.
Gonna start sheeting...

Marcus

MarcusCordeiro · « **Reply #40 on:** November 25, 2012, 02:00:18 PM »

I wish I could move faster with this bird...
Anyway, i got the stab sheeted.

Marcus

Avaiojet · « **Reply #41 on:** November 25, 2012, 07:41:22 PM »

Marcus,

Looks good so far!! It's shaping up so keep up the pace!

I know absolutely nothing about the model you're building, but looks like you have it under control.

What did you wind up using for an adheasive to sheet with?

I did google to see what the model looks like.

It's a great looking model! Sig has their's painted in sky blue.

Ideas for color yet?

Charles

MarcusCordeiro · « **Reply #42 on:** November 26, 2012, 01:51:29 AM »

Charles

I used Brodak's Finish Resin. I couldn't get the ZPOXY, but it is said to be good too.
It was my first time sheeting foam, then later I'll get them out of the cradles and see the result.
I followed Bob Hunt's tutorial and it was kind of easy.
The resin is easy to spread and there's plenty of time to place the skin on the foam.
The wings to come soon...

Marcus

Avaiojet · « **Reply #43 on:** November 26, 2012, 08:22:43 AM »

Marcus,

This is not advice.

I used to cut foam wings years ago. Sheeted plenty of them also.

Tried all kinds of adhesives. Near the end, when I had just about stopped doing foam wings, I found myself taking the skins and wings to my local Woodcraft Shop.

They would spray the surfaces with the glue they used, "commercial grade," for laminating Formica and veneers.

They never charged me because I would bring in coffee and donuts. Actually true.

These wings were sheeted exactly that way, in the 90's, and show no evidence of separation. Light too.

Worked for me on a bunch of foam wing cores.

This wing, the last of my foam wing models, and will be the last, is for an electric DF jet I'll eventually get around to completing. Eventually.

Charles

MarcusCordeiro · « **Reply #44 on:** November 28, 2012, 03:20:45 AM »

Charles

That's great advice. I sheeted the stab using finish resin and liked the result.
It was kind of easy to do. Just didn't like the fact that the stab cores were a little different from one another
and that made it a little difficult to get them aligned. I'm considering building a new stab, but a build up one
so I can get it straight.
That sucks...

Marcus

Jim Oliver · « **Reply #45 on:** November 28, 2012, 05:23:57 AM »

Quote from: Jim Oliver on September 12, 2012, 09:49:33 PM

Marcus,

I would suggest that you carefully check the cores, bith wing and stab, to make sure that the cores are identical. When I built my first Magnum, I found that the wing cores were different thickness.

I didn't discover the problem until after the cores were sheeted and ready to join. I was NOT pleased

Jim

MarcusCordeiro · « **Reply #46 on:** November 28, 2012, 08:23:29 AM »

Quote from: Jim Oliver on November 28, 2012, 05:23:57 AM

Yeah... Dumb dumb here only checked the wing cores...

At least, the wings seem to be ok...

No biggie though...

Marcus

MarcusCordeiro · « **Reply #47 on:** November 30, 2012, 09:28:47 AM »

Dumb dumb

is going to build a buildup estab...
No way to save the foam one.
Well, let's have some fun cutting some balsa.

Marcus

MarcusCordeiro · « **Reply #48 on:** December 18, 2012, 06:50:59 AM »

Back in action.
I'm sure I can get the sheeting on those wings done today.
By the way, what a poor cutting job Sig did with the wings...

And got started on the new stab...

Marcus

MarcusCordeiro · « **Reply #49 on:** December 19, 2012, 09:44:23 AM »

Wings sheeted as per Bob Hunt's tutorial, Though I didn't have 200 pounds of weight, so had to satisfy myself with around 60...
The only way to get 200 lbs over those wings would be me sitting on top of them...

For a first timer, I guess it is very good!!

Marcus