cosmic wind

[bob lindsay]

    I,have recently built the Brodak Cosmic Wind . If anyone else has built one lately, where did you set the balance . The plans call for 1 1/2 " back from the leading edge . I have done this  but I feel thi may not be right
   I flew the plane but it could be nose heavy .I have not had a lot of experience with flying or balancing
  Any comments would be appreciated
                                        thanks Bob Lindsay

[Ray]

Seems to me I recall we were setting it closer to the wing spar than 1 1/2" from the LE, unless you meant that it said from the rear edge of the shaped LE piece.  I'm betting we were looking for something closer to 2 1/4" from the front of the LE than to 1 1/2".  The worst thing about the Goldberg Cosmic Wind was the very low wing in it compared to the vertical CG.  You would get a lot of flopping around from that at the intersections of eights.

[Paul Smith]

I just test-flew mine.

It balanced at about 2-3/8".  A bit jumpy, but flyable.  I'll probably sneak it forward a bit for the next moto.

[Bill Little]

Hiw dies the Green Head run with the tongue muffler?  Any overheating issues?

[bob lindsay]

    Ray where on the leading edge did you measure from? Tip of the wing or up near the fuselage?
       



                                               Bob Lindsay

[Paul Smith]

In this case, the LE is straight, so it doesn't matter.   But I just measure the root chord at the fuse, even if it is tapered.

----break --- break --- new issue ---

The Big Art tongue muffler works great.  No loss of pwer or overheating.   I have several in use.  I have even blocked few holes to further enchance economy.  No prob-leeemm.

[wwwarbird]

Bob,

 Noseheavy is OK unless it's really extreme. Noseheavy will be more stable for you, but if it's too much so, it will hurt you in your maneuvers. I typically don't even worry about what the C.G. is on the plans for models of this type, like the Cosmic Wind.

 Here's a good way to tell where your at:

 When nearing the end of a flight, just fly nice flat level laps about 10' high or so. Flying level at this height, when the engine quits, don't do anything with the handle-LEAVE IT AT NEUTRAL-and let the plane glide. If the plane wants to drop immediately on it's own, you are noseheavy. If it seems to climb and want to stall, you are tail heavy. Beyond that, you just trim your balance to your personal liking, don't worry about what the plan says.

 

[bob lindsay]

        Thanks to all for your replies
                 Tite Lines To All   Bob Lindsay

[don Burke]

I think Keith posted the idea to use the percentage of the stablizer area to the wing area as the the position on the Mean Chord for the CG.  25% stab, 25% of the MC for a starting point.   The mean chord being the average of the tip and root chords on a straight tapered wing.

[Phil Coopy]

What Don said.........I redid both my Fancherized Twisters that way and they fly a whole lot better than where the plans had the CG. Still tweakin' on it but it's pretty close to what I like.

Phil