Hello and thank you for your comments.
Please see the attachments.
Paul,
I have many C grain planks with "contest" stamped on them. Most of them were initially reasonably straight but, after half a year in my basement, they are all bent and some are also twisted to different degrees. I gather they were sold not properly dried and only now they dried, bending in the process. It is very hard to find a good quality balsa in Toronto and the problem is growing. I may order the presumably high quality balsa from one of the warehouses in the US but only the time will show if this wood is more stable.
Everybody,
My flaps are dead straight at this moment and reasonably stiff in torsion before covering.
Unfortunately, there is no numerical criteria for this stiffness so, like in many other cases, we are left with opinions based on experience.
I have a limited experience in building the 60" wings span planes. Specifically, MP Max Bee is only my second plane of this size.
The first one (Intrepid XL called Great White) was smashed to splinters before I could fly corners and the flaps in it were probably too wide anyway for the modern stunt.
The main question again: if I remove about 15% of the flaps weight by drilling the holes (see the proposed holes pattern on the photo, please) and cover the flaps with Silkspan with Doculam on top.....Will they be stiff enough for the good quality corners? The torsional stiffness of the rectangular cross section (J) can be calculated but this number is very conservative. When the flaps are covered with Silkspan and Doculam, the diagonal tension developed in these coverings will stiffen the flaps in torsion but how much?
Are we talking 10%, 50% or more?
Again...it would be good to know the test results of similar flaps from the well flying plane to establish the numerical criteria.
Regards,
MP Stunt Academy