Howard Rush is the guy to ask. He's been doing flaps with carbon tubes for a bit.

If I recall the vector 40 uses solid flaps. The ones that came in my kit were just fine as is. Once you cover them they stiffen up just fine. They are not large enough to stress over. If you still wish to stiffen them cover them with Carbon Fiber veil instead of silkspan. That will be more than stiff enough for a Vector 40. CF tubes are more for built up, large model flaps with high loadings. Complete overkill on the vector.

Thanks guys, thats all I needed to know. I will not use this method on the Vector. Yes the flaps have been glassed, but using dope, very soft. i will remake them in C grain. I wish I would have used CF veil, but still not sure it would be stiff enough.

Thanks guys, thats all I needed to know. I will not use this method on the Vector. Yes the flaps have been glassed, but using dope, very soft. i will remake them in C grain. I wish I would have used CF veil, but still not sure it would be stiff enough.

It would be easy enough to strip the dope/fiberglass off the existing flaps. Use thin epoxy finishing resin with either .75 oz fiberglass (on a 45 deg. bias), or .5 oz CF mat. If one layer isn't stiff enough to suit you, add another.

FWIW, Howard was not satisfied with torsional stiffness of the usual unidirectional CF tubes, so rolled his own with the CF on a 45 degree bias. That's Howard for you. When PW test flew Howard's plane, he reportedly said the flaps were too stiff.   Steve

Here are some pictures:

1. A roll of carbon-epoxy prepreg from the local airplane factory surplus store and aluminum arrow shafts from Lancaster Archery.
2. Wrapping a strip of prepreg on the arrow shaft.  Width is calculated to make a 45-degree wrap. 
3. Wrapping a ply in the opposite direction.  This time I left the backing paper on until I did the wrapping.
4. Wrapping the tube with polyester shrink tape.  The pink stuff on the tube is .001" Teflon to keep the shrink tape from sticking to the part.
5. Putting the tubes after cooking in the autoclave into the Reactor.  Note the authentic chemical ring stand. 
6. Adding water to the Reactor.
7. Add acid to water, not the converse.  Remember that?
8. After a little time, the reaction starts to go fast.  I shoulda used a bigger diameter Reactor.

But no operational stunt planes like this shop:

Five months on, I've made a little more flap progress.  Here are pictures:

1. Slitting the tubes for nylon hinges.  This is a Dremel Dangerous Disk mounted in a router on a router table.  The block, rod, and arrow shaft segment taped to the carbon tube hold the tube orientation so the slits line up.
2. Using a plug cutter to cut balsa dowels for hinge anchors.
3. Cutting the dowels in two with a band saw.  A piece of 1 x 2 with a hole the size of the dowel is clamped to the saw table in front of the blade.  A ramrod pushes the dowels through the blade. 
4. Cramming the split dowels into the torque tube using the other end of the ramrod, which has an old X-Acto blade glued to it to align the splits in the dowels with the slits in the tube.
5. When the split-balsa-dowel hinge anchors are in place in the tube, I use a piece of Teflon to hold the split open while I Hot Stuff them in place. 
6. You can see the end anchor.  I finish the flap before installing hinges.

Did you make the hole in the foam first, then stick in the tube, then cut the flap? 

Howard ;

Sheeted the flap, made a front LE from 1/4 - bevelled out the balsa leading edge to accommodate the carbon torque tube - which is precut for my hinge slots ( which is a pain to do! ). Epoxy it in, epoxy that to the foam finish as per normal.

To cover the flaps, I lay .58oz Glass cloth over the whole flap, then .3 oz carbon veil - standard PTG finishing method from there on.

VERY stiff flaps.

With the addition of my Rush boost tabs of course!