Modify four-star 40
 

I am thinking about building a four-star 40 over the winter, and was thinking about doing some modifications to it. I was planning on a balsa cowl, the reversed canopy , and a sheeted turtle deck, all of which I have seen done, and like the way they look. I was also thinking about adding counter-balanced to the elevator and rudder, see diagram below. I was wondering what the experts in the forums thought about doing this.

Thanks,

Jacob

RE: Modify four-star 40
 

There are quite a few threads on this

Here is a good one by Swager

http://www.rcuniverse.com/forum/m_18..._1/key_/tm.htm

http://www.galip.net/Sig4Star

and a really good one

http://www.renderwurx.com/rc/sig4star/

RE: Modify four-star 40
 

I have actually already reat all three of thos posts, and that is were I got some of the ideas, but what I was really looking for is more information about others adding counterbalances to the Elevator and Rudder, I was also thinking about increasing the Aeleron(sp?) size.

Thanks,

Jacob

RE: Modify four-star 40
 

Something I would have done was add more support in the area in front of the canopy, mabey get some of that foam in a can at home-depot and sand it to shape. Iv already cracked the balsa and i think mabey one of the supports because thats where i pick it up from.

John

RE: Modify four-star 40
 

Why do you want to add the rudder/elev balance tabs -- are you experiencing flutter? That mod is a fair bit of work & unless well engineered, it can weaken the assemblies. There is less lateral space for hinges, & the unsupported outboard sections will try to flex -- thus loading up the outermost hinges & possibly leading to premature failure. If it is just for appearance, I wouldn't bother.

RE: Modify four-star 40
 

britbrat,

I have not even built this plane yet, but was looking at doing it to increase control, and possibly make it a little more aerobatic.

Jacob

RE: Modify four-star 40
 

Jacob, the 4*40 flies great stock. You may want to add 1/2-1 inch to the rudder for better knife edge

RE: Modify four-star 40
 

When enlarging the rudder, should I just leave it square, or make it more pointed at the bottom like that on the Extra.

Thanks,

Jacob

RE: Modify four-star 40
 

I enlarged the rudder on my 4* I simply added 1" and then traced the original shape of the rudder.

Sanded it and put it on.

However I have noticed one trait that I do not like when I now use rudder on to turn the nose goes down.

Easy enough to take care of but annoying none the less.

Has anyone else noticed this? Or is it just me!!! (Which is a destinc possibility!)

Mike

RE: Modify four-star 40
 

Justa add 1" to rudder, I have the stock and it might need some more rudder, but the elevator is plenty enough but rudder could use more.

Also adding counterbalances is not worth the trouble as they are not huge surfaces and they are solid balsa.

If I would do againg I would put two aileron servos to the wings and forget the tarque rods. That would be all the mechanical changes.

It flies nice and fun plane. Put a nice .46BB engine and you will have plenty of power.

RE: Modify four-star 40
 

That's normal for the 4* It pulls a little to the belly but nothing a little up elevator can't fix

RE: Modify four-star 40
 

This is a typical thing with the 4*...Mine pulls to the belly just a little bit but nothing some up elevator mix can't handle

RE: Modify four-star 40
 

See this plane is so easy to fly I did not even notice the plane going belly down before I modded the rudder.

I also did a 1/2" on the elevator, big difference snaps real nice now!!!!

Mike

RE: Modify four-star 40
 

It's so slight that at first I thought it was wind or me dumb thumbing it.

If you really want it to snap well, chop a bay of each wing. Even on the ARF, it's not that hard to do. It will still fly well and roll and snap much better.

I know guys that did 2 bays on each wing. Rolls and snaps really went through the roof but low speed handling went south.

RE: Modify four-star 40
 

Also add 5/8" to the ailerons and elevator.......1" to the rudder seems like a lot.....mine has 5/8" added to the rudder, and it pitches down sharply in level flight with rudder application.....took me by surprise on my first landing with it! It was easy to get used to, but wouldn't 1" added to the rudder make that tendency even worse?

RE: Modify four-star 40
 

It really did.. I about jumped the first time I gave it some rudder... did not touch it for 3 flights after that.....

Now it does not bother me much.... Might take some off... see how it does....

Mike

RE: Modify four-star 40
 

If you put a reverse taper on the rudder when you add material (make the bottom wider than the top) it should reduce the pitch-to-belly trim change with rudder input.

RE: Modify four-star 40
 

Cool... did not know that.. how much are you talking about? would it be a gradual taper through the whole rudder, Top to Bottom? Or just a mass of material at the bottom?

Mike

RE: Modify four-star 40
 

Very interesting, brit....I didn't know that either!