Cut out center of wing? OK?

[Rudy Taube]

I need to make room for the 8 1/2" long, 1 1/2" sq, battery in my Electric. powered # 2 Vector 40 (#1 will be Aero Tiger powered :-).  I want to see how the Electric power system, that has worked perfectly in my ARF P-40, stacks up against the legendary Aero Tiger. Using the same plane seemed like the most accurate way to do this.

I need to cut out the top wing sheeting between the LE and the main Wing Spar and within the insides of the fuselage. I plan on boxing in the sides and bottom of this area to help make up for the missing balsa.

I would appreciate any input you may have on the best way of doing this. ...... Should I FG the area for additional reinforcement? Will it be too weak? Or? .... TIA for your help.  :-)

Quote:  Old USAF saying: "Never fly in the same cockpit with someone braver than you" ;-)

Merry Christmas and Happy New Year to all

[frank carlisle]

You didn't say if this is an ARC-ARF or Kit built plane.

If kit built then substituting the two center ribs with 1/4" ribs and a good fit and glue joint to the fuselage will do the job.

If ARC or ARF I think that if the leading edge remains intact you witll still have good structiral strength after removing the sheeting. A bulkheaad at the spar would guarantee it.

[Bill Little]

I need to make room for the 8 1/2" long, 1 1/2" sq, battery in my Electric. powered # 2 Vector 40 (#1 will be Aero Tiger powered :-).  I want to see how the Electric power system, that has worked perfectly in my ARF P-40, stacks up against the legendary Aero Tiger. Using the same plane seemed like the most accurate way to do this.

I need to cut out the top wing sheeting between the LE and the main Wing Spar and within the insides of the fuselage. I plan on boxing in the sides and bottom of this area to help make up for the missing balsa.

I would appreciate any input you may have on the best way of doing this. ...... Should I FG the area for additional reinforcement? Will it be too weak? Or? .... TIA for your help.  :-)

Quote:  Old USAF saying: "Never fly in the same cockpit with someone braver than you" ;-)

Merry Christmas and Happy New Year to all

Hi Rudy,

Merry Christmas to you and yours!

I have seen (and done) what you are describing several times.  As long as you box in the area (no weakening of the spar, either) there has been no problems in doing that.  Evidently, there is not as much load on the LE area as there is the spar. As I've said before, I don't make science projects out of our models, I just go by what others have taught me and what works. YMMV.

Happy Holidays!
Bill <><

[RC Storick]

As I've said before, I don't make science projects out of our models, I just go by what others have taught me and what works. YMMV.

Happy Holidays!
Bill <><

What you don't use any PI X radius squared dived by the biffle plate to coincidence's to the congruity of the angle + the Reynold's numbers = Destruction of the airframe? You just go by practical experience? How could that work? I thought everyone made a science project out of it. I do       

PS. By the way I will work on your skins this week.

[Bill Little]

 


Hey, Sparky, you know me better than that!

Bill <><

P.S. Thanks on the "skins"  gonna need them soon this coming year!

[Ward Van Duzer]

Bobby Hunt taught me the most important math formula in model building.

T.L.A.R.










That Looks About Right!

[Steve Helmick]

TLAR...yeah! I don't know what the existing structure is like, but assuming it's a "C-tube" with 3/16" square spars (or bigger?), I think cutting away the center LE sheeting is a pretty serious move. I'd put a spruce doubler on the spar to make up for the loss of strength. Taper the ends over at least one rib bay, two would be better.  There's still a reduction in torsional stiffness to worry about.
Be real careful to make sure the front leg of the bellcrank can't possibly hit the battery box floor.     Steve

[Bill Little]

Hi Steve,

I guess that adding some extra reinforcements wouldn't hurt, except in the weight area, but since we overbuild so much..............

My experience in the area is under the guidance of a certain Mr. Werwage.  I had a problem getting a big enough tank into a plane and talked to him about it.  His advice was to box in the area with thin ply (1/32), and make sure the glue joint was good where the LE meets the fuse sides.  And make a good epoxy fillet.  So far, I don't know of any of his planes folding a wing, and he, and Bobby Hunt cut out the LE when necessary.  Of course, we can get much bigger clunk tanks (and custom made "plastic" tanks) in where we used to use metal tanks. 

The plane I did it on suffered no ill effects.

Bill <><

[Rudy Taube]

Thanks for the help Guys :-)

Frank:
     It is an ARF. Your right,  it would be an easier mod if it were the kit.

Bill:
     Thanks for confirming that this should be an OK mod.  In my 37% RC planes the wings only have the support of the main wing spar in the center section. There is nothing else, no LE, no rear spar, etc. And I think they take at least as much stress as our CL planes.
     If I had more energy, I would build a CL Elec. with this type of wing. Using plug in wings would free up this entire front area for a battery, and make the plane very easy to store, and transport. :-)

Steve:
     Thanks for the tip on the Bellcrank. I forgot all about that being in this space. I should have looked closer through the rear hole in the wing. It is a 4" BC, and it is neatly suspended in the very center of the wing, so it takes up a lot of room close to where I want to be. 

BTW, this is a beautifully built ARF. It is very strong in all the right places with excellent workmanship throughout.

This ARF will have the Aero Tiger. After all your comments, and looking closer at the room (or lack of?) inside the fuselage, I am going to get an ARC for the Elec. I plan on  taking a saw to the entire top of the fuselage. This will allow me to insert a 1/2", or 3/4" piece of balsa for the entire length. This should give me enough room for the battery without changing any of the planes excellent flight characteristics (I hope! ;-).
     I plan on keeping all the important factors in tact. Prop location, Wing, stab, RD all in the exact same relationship. With a little luck it should not look to dorky.
   
     I will definitely be using Roberts way cool formula to insure that I get all the flight parameters correct and keep the planes modern "High Zoot" status! I'm sure Randy used a similar formula when he designed the original.  ;-)

Thanks again for all your help.