camaro2007

Hi all
As most of you know im putting an OS LA .15 in a mini telemaster. Im building up the mini telemaster wing by replacing the kit 1/16 ribs with 3/32 ribs, I was wondering something about the turbulator spars, is it stronger to glue pieces of them in between each rib like the kit recomends or is it stronger if i cut notches into the ribs and glue down one continuous turbulator? Since im cutting new ribs i wouldnt think it would be much harder to cut some notches in them.

thanks
Eddie

g-rock

My Feedback: (1)

Hi,
I do not know what a turbulator spar is. But if that is just another name for the main wing spar, it is definitely stronger if continuous.
Gene

camaro2007

its those spars that go forward of the main spar, i think thats the name of them at least.

look here http://www.hobby-lobby.com/srtele.htm there are six pictures look at the one in the middle on the bottom row, thats the senior...would it be better to have continuous turbulators?

rainedave

My Feedback: (1)

Turbulators are placed in the first 15 to 20% (typically) of the chord to generate turbulance over the top surface of the airfoil. It helps the lift. I used to dope thick thread lengthwise on top of the Jap tissue on my FF models for the same purpose.

Yes, a continuous spar is necessary. If the design does not already include shear webbing between the main spars I would add that, too. At least for half the span. I'm still not sure why you want to fly 3D with a Telemaster[]

camaro2007

im not ging to be flying 3d, i just think after building it up nice a sturdy it will be around 28 oz. maybe 30 oz flying weight, I would think a .15 would fly nicely.

rainedave

My Feedback: (1)

Sorry. I get confused easily. Somewhere on this forum today someone was asking about hovering. I guess I thought it was this thread.

combatpigg

My Feedback: (3)

At that size and weight, you will end up with a pretty sporty plane! If those forward spars are made out of what I suspect is 1/8x1/8 balsa, they will be too easy to break from rough handling if the wood isn't tough. In this case I would use spruce or real hard balsa. I taught my sister the basics of flight with a plane just like this. After about an hour of air time, she was basically on her own.

camaro2007

thats ok, i bet i get confused more easily then you do.

combatpigg would you notch the ribs and use a single piece for turbulators instead cutting up pieces and gluing them in between each rib...would it offer more strength? would 1/8x1/8 hard balsa or spruse weigh much more? I was planning the sheet the forward part of the wing with some thin 1/32 balsa to offer alittle more strength

rainedave

My Feedback: (1)

Dude, it was you! But you were talking about your MUS, not the Tele. My bad.

camaro2007

see i forgot too, haha

combatpigg

My Feedback: (3)

Gluing them in pieces is ridiculous! I would use a razor saw to make the slits in the ribs, layout the marks with a fine line marker and ruler [after the wing is built] and install full length 1/8x1/8 spruce or hard balsa. The wing could be built without those little spars, I don't know if they are worth the trouble. Make sure the center section is well braced, I would use 1/16" ply for a dihedral brace, glued to the back side of the main spars, it should extend out one rib bay each side of center. You will have to cut the center rib in half to work this piece in. Then glue 1/16 balsa vertical grain to the back side of the spars out to half span. that should keep the wing from folding........but hey, if you don't fold one every now and then, you are probably building too heavy.

rainedave

My Feedback: (1)

CP is giving you great advice. And, seriously, having a model fail will teach you more about balsa construction than probably anything else. I remember putting a TD .09 on an .049/.051 FF design only to see the wings fold back. It had a geodetic wing so I figured it would be strong enough. If I'd had carbon fiber then it would have climbed like an Estes rocket.

mylamo

My Feedback: (1)

That Mini Tele has a funny wing. The 1/16 ribs are ok but like cp said the dihiedral brace needs to
go one more bay. The turbulator spar is just placed on top of the ribs.Ugly but ok. Shear web the
main spar and use a gusset on both sides of the ribs at the trailing edge. After it is covered it
becomes real sturdy

KidEpoxy

ok, I have a terminology question
Are ALL the 1/8sqr sticks that are notched into the ribs on the front slope of the wing called Turbulators?

Cause one definition I read a few posts above made them seem as additional or helpers to the foil on top. The ones I've seen notched into the rib seem just to keep the cover from caving in below foil line between the ribs for unsheeted wings. Are these covering cave-in stoppers Turbulators same as the on-top airflow disturbers?

rainedave

My Feedback: (1)

Those smaller spars that are flush with the ribs still act as turbulators to a degree because the covering stretches over them creating high points in the wing's surface. I guess technically they are spars, but if your covering is shrunk nice and tight the resulting lengthwise ridges do cause turbulance over the wing.

Take a look at Dick Korda's and Chet Lanzo's wing designs. They incorporated a series of small spars forward of the airfoil's high point. They did three things: strengthened the wing with less weight than D-tube sheeting, helped to preserve the forward curve of the airfoil, and functioned as turbulators. Actually four: they were beautiful to look at, too. Those guys had it all figured out. We just repeat what they did.

KidEpoxy

"but if your covering is shrunk nice and tight the "

That is a big IF, the way I cover

ptulmer

My Feedback: (5)

The T-spars contribute a teeny-tiny bit to the torsional rigidity, but nothing to the overall strength of the wing. To sink one in, though, you stack the ribs and cut the 1/8" square slots all at once. Put shear webs out to the wingtip if you want to. (it won't hurt) The shear web's job is to prevent the spars from sliding, preventing the wing from flexing. The more, the better when you don't have a d-tube leading edge. (which contribute quite a bit to shear prevention)

Go ahead and do it front and back of the spars. Making a box out of it will increase the torsional rigidity, too. Someone else, (Ebeneezer) PM'd me about the wing center section. That was his idea, and I plan on using it on a Surestart version. Student pilots.[&:]

BMatthews

They got the name Turbulator Spars from the free flight world. As mentioned they perform a lot of multiple functions and oddly enough only help to turbulate in special cases unless a thread or other turbulator is used as well.

Hard 1/8 square should be OK but a better option would be 3/32 by 3/16. The amount of wood is the same but the extra depth will provide more strength against accidental crushing.

Main spars on this new hotrod version should be top and bottom spruce with back and front balsa shear webs out to about the 2/3 span point and single shear webs to the tips. The center 1/3 on each side should be very hard 1/16 except the joiners at the root that should be 3/32 ply front and back. Some kevlar thread wrapping wouldn't be a bad idea either. One brace should probably run out for two rib bays and the other to about 1 or 1 1/2 rib bays. DO NOT make them the same length as that produces a rigid stress riser point. You want to build in a graduated sort of bracing so the wing can flex smoothly.

And to help support the covering better I'd also suggest an additional turbulator spar that is locaed about 3/4 or 1 inch behind the top main spar. So two turbulators on the front and one behind. That'll result in a smoother top surface that should make a noticable difference in the "hang time" in the glide or slow flight. And the spruce spars and double dihedral braces along with the webbing will provide a super strong spar.