Looking ahead to something to build to get the juices flowing.  I want something Classic and I have never built a swept wing I-Beamer.  Wanting to know if anyone out there has built the Demon?  Or did anyone see Jack's fly?  I plan on powering it with a HP .40.  I have the original magazine and plans.  And a 1/72 scale plastic model to help me with the shapes and such.

One thing puzzles me a little, how to figure out the lead out position with that swept back wing. ??

Thanks!
Bill

Bill
  Having built a few swept wing stunt models I can tell you the bellcrank location is the problem most off the time with a poor flying model. A friend Mr Waldorf back in the early 1950's built a swept wing model. I have that model. He put the bellcrank in the normal location and ran the leadouts in the normal position,for those days. It pulled excessive and flew pointed out. I built my "JET" in 1965 that I still have and put the bellcrank far back in the wing so the leadouts come out at 90 degrees to the body right at the leading edge. There have been many articles on bellcrank location not making a difference but they are wrong in this situation. The leadouts need to come out at 90 degrees to the body. I talked to Jack about this when he was a Tampa Bay member and he agreed. When he first built his swept wing models he placed the bellcrank in the then normal position and had to bring the leadouts out forward of the leading edge to keep the model from hinging in turns. He later made changes to some older models and they then flew better. My JET has extreme sweep back and fly like a normal stunter.
 I moved the leadouts forward some on the old Waldorf jet but without taking it apart I could not move the bellcrank and it flew better but not great.
 This old jet of Waldorf's is old time legal so it would be worth building with a better control system.
    Several have asked for plans of the Waldorf jet  but I have not drawn them and have no plans to do so at this time. I have agreed with the family not to loan the model to anyone. If some one wanted to spend the day here and draw plans of the model that would be fine.
Ed

I am not trying to beat a dead horse.  But some things need to be clarified here regardless of what has been said on this thread and other comments about the Sheeks' swept wing stunter.

As with any stunter, the position of the bellcrank can be anywhere.  However, there is good reason to place the bellcrank somewhere near the CG.  There may be some structural limitations that do not permit the location to be right on the CG, but whatever the design, it is still desirable to place the bellcrank near the CG.

Given the leadout position relative to the CG, it is desirable to have the bellcrank near that CG to reduce to some practical limit the angle the leadouts must take at the exit point of the leadout guides.

So, where does the CG belong on a swept wing model?  There are already some recent posts that show how to determine the mean aerodynamic chord (MAC) of a wing and its location relative to the root of the wing.  A beginning point for the CG of the model would be probably between 22% to 25% of that MAC.  That will place the CG well behind the  LE of the wing at the root, depending on the amount of sweep back.

Then, there are other programs available, some referenced in other threads as well as the calculations/nomographs by Bill Netzeband years ago that show where to place the leadouts relative to that CG.  (The suggestion that the leadouts should be 90^o to the fuselage for the swept back wing only works if the bellcrank is already in a position maybe slightly behind the correct CG.)

Figures published years ago, supported by Bill Netzeband's nomographs and many computer programs later from these forums show (most derived from the work of Bill Netzeband and Peter Soule) that for a .35 size stunt ship, weighing in the neighborhood of 40 to 45 oz, on 60', 0.015" dia lines, a good starting place to locate the leadouts will be about 2^o aft of the 90^o position from the CTG published at the same time as those nomographs is to locate the leadouts behind the CG on that .35 size model about 0.36" for every 10" span of the inboard wing.  Different models with different weights and different lines will all change that initial line rake position.

These calculations for MAC, the determination of the CG  and the calculations for the line rake relative to that CG all work to determine a good starting point to locate the leadouts.  It is not different for a tapered swept back wing.

Keith