Stuka Stunt Main Forum · 14 of 14 known posts recovered
What are the general thoughts on installing the bottom block?
I don't know what general practice is, but I would tend to build a Skylark the way Ed Southwick designed it.
The plans in the December '63 MAN article on the design don't specify the direction of the grain of the bottom block, however it looks like 1/16 sheet to me by comparison to the other parts. Which I would normally install with the grain crosswise.
Southwick is adamant in his article that alignment is crucial to getting a good flying airplane. He goes to some length to draw lines to line up the fuselage at 90 degrees to the spar and zero out all the incidence. (There have been those who later say that a half degree positive incidence on the stab is good, but that's another thread.)
The article says "Plank your fuselage bottom before permanently attaching your stabilizer, as the planking usually twists the fuselage slightly and this twisting will certainly tilt the stabilizer you had aligned so nicely." There is no mention in the article of which direction the grain is on the planking.
The Smith Model Products Skylark kit I have shows a 1/4 inch block of balsa on the bottom of the fuselage from the tail to the gear, the grain going lengthwise. This block is supposed to be hollowed to a 1/8th thickness. There is a somewhat cryptic note on the plans. A demarkation line about an inch forward of the trailing edge is drawn just below the bottom of the fuselage block. An arrow pointing aft is labeled "Flat" and an arrow pointing forward is labeled "Curved". Which plane is curved forward of this line is not made clear.
I'm given to understand the SMP kit was produced with Ed's approval, so I am assuming the bottom fuselage block--similar to the one you describe for the RSM kit--is the construction method he designed.
For what that is all worth.
My Tom Lay prepared ST .46 arrived today, complete with the Plasma/Ceramic piston/liner pair from Tony in OZ. I've got a virgin Froom 2 inch needle nose spinner set aside for the project so I'm about ready to go when the time comes.
Keep us posted on your progress.
Cy.
The Cat Whisperer
A few examples, the RSM kit doesn't show a rib half way out on the wing tips but the other two kits have the rib. All the pictures I have seen of early Skylarks have a built up rudder like the Sterling kit but the RSM and Smith kits have a solid rudder. The Sterling kit has a 3/32 fuselage bottom cross grain and the other two have 1/4 hollowed bottoms. Ed approved all 3 kits so one can only assume all 3 were more or less correct at the time they were produced.
I am going to add the rib in the wing tips and have built up the rudder like the Sterling kit. I also air foiled the rudder as in the Sterling and Smith kits, assuming the period rudder was air foiled, not symmetrical like the RSM kit. This will probably make trimming a bit harder but I am really trying to stay true to the original design (at least as far as outward appearance is concerned).
Sure wished Ed was still around...
Bob,
Ed planked the bottom of his Skylarks with a hollowed 1/4", 5lb., C-grain sheet. He built all of his airplanes from the beginning (1950's)with a solid 3/8" thick fin/rudder, airfoiled on the inboard side. He was adamant about installing the bottom planking prior to installing the stab as the planking will usually induce a slight twist in the fuselage.
Ed was not happy with the Sterling kit as it was not produced per the plans that Ed approved over a dinner with Ed Manulkin of Sterling. Many things were changed on the kit without Ed's approval to make it more convenient for Sterling to produce it.
The Smith and RSM kits of the Skylark were produced as Ed approved them.
Bill Byles
This helps allot. Guess I will skin my already built up rudder so it will look like a solid chunk of wood 
Naw, just an early bird, I like to tinker in the mornings before the rest of the world starts bugging me.
I grew up installing the grain crosswise, but I have seen no engineering studies that provide any conclusive evidence for one type of construction over the other. I'm sure they exist, but I never got into torsional rigidity when I worked for a structural engineering firm. (I was the Diving Supervisor.)
Unless it's a bottom block that should be hollowed out, I still cut and glue the skin crosswise.
Ron King
Excellence is born of preparation, dedication, focus, and tenacity.
Compromise on any of these and you become average.
Disclaimer: I am neither a NATS Champion, engine reworker, engine producer, column writer, Hobby Shop owner, *rockeet* scientist, nor otherwise. Just an old Advanced flier.
My planned set-up as well.
Hmm.
Maybe at VSC 2K5 we could have three of them flying.
Hmmmmm.
Formation syncronized acro anyone?
Cy
The Cat Whisperer
Disclaimer: I am neither a NATS Champion, engine reworker, engine producer, column writer, Hobby Shop owner, *rockeet* scientist, nor otherwise. Just an old Advanced flier.
Phil C
Just use a 1/16" ladder crutch in the aft part of the fuselage and then it doesn't matter how you orient the blocks. The ladder crutch will create the stiffness needed. Call Tom Morris, he can give you an idea how to do the ladder crutch. He does then on his planes so that he can use 1/16" sides. Give him a call!
Jim Pollock 