Magnum Flaps and Elevators

I'm currently finishing my Magnum and wanted to know if most build the builtup flaps and elevators, or replace them with solid balsa. I'm at the point of no return and was looking for help.

Thanks,
Zuriel

I used light solid "C" grain sheet stock for both. Worked fine and was light enough.
Bill <><

Mine are a bit O.T.T
1/8 balsa frame
Infill with 1/8 Depron sheet
Skinned with 1/16 balsa epoxy bonded in a press.

Light 'n' Stiff

Good Flying

>I'm currently finishing my Magnum and wanted to know if most
>build the builtup flaps and elevators, or replace them with
>solid balsa. I'm at the point of no return and was looking
>for help.
>
>Thanks,
>Zuriel

Zuriel,

The built up flaps on the Magnum work just fine if they are covered with silkspan and dope. But because they are so close to the C.G making them from light "C" grain would be OK to.

Do not make the elevators from solid sheet. They are too far behind the C.G. and may require additional nose weight to properly balance the model. There is nothing worse than adding dead weight to the any model.

One other option to consider is sheeting the flaps and the elevators with 1/32" contest balsa. This would be stiffer and lighter than solid sheet balsa.

Mikey,

I would tend to agree with you that using solid sheet Elevators on the Magnum would be a risky proposition; however, I did it and my plane balanced just slightly nose heavy - but I wouldn't recommend this method of doing it though! You need to go through the Balsa stack and find the lightest contest grade 3/8" balsa you have and then use sanding templates and taper them to a 1/8" thickness at the trailing edge. This is the one step that is not easy - it takes much sanding with an 80/100 grit sanding bar block sander, and edge templates to get everything perfect. I must have spent about 4 hours sanding on each elevator - whew! The plane flew really good though when I finally finised it!

Jim,
I, also, used sheet stock for the elevators. Also got a slightly nose heavy condition! Used the good ol' ST 51.
I, however, use the old fashioned way of carving the flaps and elevators. I am too impatient to find all the rods, etc., and with a sanding belt glued to a flat edge of the table, my Solingen razor plane, and having done it so many times that way, I can do it a lot faster.
I WOULD recommend the rod method to those that haven't had much experience carving these things. It does assure a good piece.
Bill <><

Bill,

Yeah, agree if you have a lot of experience that way it cuts down on the time. This was the plane I built in Tom Morris's shop and had access to all his tools and gadgets. The Square bar stock works better than rods, they don't roll around on you!

>Mikey,
>
>I would tend to agree with you that using solid sheet
>Elevators on the Magnum would be a risky proposition;
>however, I did it and my plane balanced just slightly nose
>heavy - but I wouldn't recommend this method of doing it
>though! You need to go through the Balsa stack and find the
>lightest contest grade 3/8" balsa you have and then use
>sanding templates and taper them to a 1/8" thickness at the
>trailing edge. This is the one step that is not easy - it
>takes much sanding with an 80/100 grit sanding bar block
>sander, and edge templates to get everything perfect. I
>must have spent about 4 hours sanding on each elevator -
>whew! The plane flew really good though when I finally
>finised it!
>
>Jim Pollock

The last Magnum I built was powered with a ST.46 and weighted in at 53 ounces. It had a tongue muffler, Bolly three blade, Veco spinner, and required a little nose weight. Replaced the tongue muffler with a Big Art expansion muffler and it balanced perfectly. That airplane was a killer and did very well for me. I still have it but all the covering has been removed waiting for a repaint.

Mikey,
Was the Magnum wing built up or foam? If it was foam, did you use slow cure epoxy for the skin application? What did you use to thin the epoxy?

I love the Magnum, I guess it is like a guy's first car, you never forget it. I built three Magnums in eight years and have two new ones sitting on the shelf.

Mike Clark
(MikeC)

Cool!!!
The Magnum kits all had foam wings. The exception to this, are the ones I built back in 79, 80, and 81 way before the kit was ever released. These were I beam models and the sizes were from 680 to 750 square inches of wing area.

Always use slow curing epoxy when attaching wing balsa skins. Sig epoxy worked really great (but you knew I had to say that) but there are other epoxy glues that work well also. It is my experience that the contact cement glues are not as good as the epoxy in the long run. The solvents from dope seep through the pours of the balsa skin and attach the contact cement, This allows the balsa skin to come loose and/or pop up. Epoxy glue makes a very affective a barrier against the dope solvents from penetrating to the foam wing.

When properly applied the epoxy used to glue balsa wing skins should only add about 1 ounce to the wing.

Yup! What Mikey said. I followed Mikeys advice and my Magnum weighs in at 54 oz.
I would have to agree, I love my Magnum, and I for one feel that the Magnum is one of the best looking C/L PA planes ever designed- it has a real classic design that will always be in style-(not to mention that it flies great too!)
Brian
PS Hi Mike! Great to hear from you!!!

>Cool!!!
>The Magnum kits all had foam wings. The exception to this,
>are the ones I built back in 79, 80, and 81 way before the
>kit was ever released. These were I beam models and the
>sizes were from 680 to 750 square inches of wing area.
>
>Always use slow curing epoxy when attaching wing balsa
>skins. Sig epoxy worked really great (but you knew I had to
>say that) but there are other epoxy glues that work well
>also. It is my experience that the contact cement glues are
>not as good as the epoxy in the long run. The solvents from
>dope seep through the pours of the balsa skin and attach the
>contact cement, This allows the balsa skin to come loose
>and/or pop up. Epoxy glue makes a very affective a barrier
>against the dope solvents from penetrating to the foam wing.
>
>When properly applied the epoxy used to glue balsa wing
>skins should only add about 1 ounce to the wing.