Tip-stall and turbulators

[east6008]

I just finished an AT-6 scratchbuild that is very light and is powered by an
OS .10, span is 36"
Test glides over soft snow revealed a nasty tip stall, and I was shocked
because it has washout, proper CG, and slow elevator rates.
Is it worth my time to rig up some sort of turbulator in the tip area, such as
pieces of pin-striping?
I tried this once on a glider, and was never convinced it was any good.
More washout did the trick

[rofujiyama]

Hi
Most scale radial engined models designed before 3D models, don't like to fly or glide, like conventional streamlined [models] :mad: . Some, also had flaps. :D You could trim the trailing edges of the ailerons [up] to see if more washout will help. Keep the landing speed up, till just before touchdown, is a normal procedure to follow, so you dont swamp out your tail surfaces at slow speeds from the big nose, or running a really large diamater prop, to keep the airflow along the body.
I like the look of a big radial engined nose, also, but flying it in RC takes a little bit of adjusting, in general, when it comes to landing, or how slow you can fly it before it stalls.

Roland ;)

[BMatthews]

Unless it's no more than about 16 oz you'll have a very hard time getting it to fly fast enough from a hand toss unless you have a strong headwind to throw it into. Even then it's hard to hold a low wing model in a way that makes such a short test throw meaningful.

I'm afraid it's time to suck it up, start the engine, have a buddy launch it so you can be ready on the sticks and deal with it. Just double check the balance point and control throws to try to get all that out of the equation.

[Batmanwpg]

Some times turbs will work and other times not. It is airfoil type dependent. Some solutions to try: 1)Turbs-they will have to be some where in the first thirty % for stall control. You will have to do lots of experimenting to find the best location.
2) Add flaps to the wing.
3) Re-build the wing but use a slightly higher cambered airfoil at the tip with slight w/o.
Check your wing carefully for warps also.
What airfoil did you use?

[east6008]

-much better now, clawed about 8 oz of weight out, too much wood,
homemade muffler too heavy, it has a floating glide from handlaunch now

[BMatthews]

-much better now, clawed about 8 oz of weight out, too much wood,
homemade muffler too heavy, it has a floating glide from handlaunch now

And it'll be a far better model for all this. Well done!

And I won't even ask about the tools of torture and destruction that were used to remove that 8 oz... :D

[east6008]

....a pair of long-handled forceps and long butcher knife.
I quote from reknowned Toronto modeler Jack Mcgillvary when
somebody asked him the secret of getting a model to fly well-
"Leave out most of the wood"
And was it Geoffery DeHaviland who said, "Simplicate and add lightness" ?
Its surprising how much redundant structure you can remove
without weakening the structure.
One of my most prized workhorse models is a Goldberg Anniversary Cub
that people find it hard to believe is powered by an Enya 09
I lit my woodstove 6 mornings in a row with wood I clawed out,
and reinforced my workbench with the wingspars.