ticketec

My Feedback: (2)

Well we're back home and I've got another week off from work so I've dived straight into the hawk.

id lost my modelling mojo towards the end of last year start of this one but I'm back on the bandwagon and loving playing with the hawk finally.

As the hawk was purchased second hand, I had decided that I would fully strip, inspect and reassemble everything on the model that was practical. I started on the L/H wing.

A problem/area of concern was the flaps. I noticed when I was buying the model that there was quite a lot of play in the flaps with the servo powered. When I looked into the setup. I saw that from the faired position to fully deployed flap was less than 5mm of servo travel. The flap would also sag when not powered. First problem I spoted was that when he was epoxied the horn to the flap he had sunk it too far down into the flap, so very little moment arm on the flight control and so very little movement required for full deflection. The second problem was that in order to clear the lower wing skin the way the servos are positioned the guy had used over 1.5" of servo arm extension which definitely didn't help the situation.

I made a new control horn out of carbon sheet and hysol'd it to the original horn. This doubled the distance from the hinge point to the attachment point. Then using some old thread rod I experimented with being able to use a smaller servo arm to use more servo travel, and therefore increase the resolution, and to get significantly more mechanical advantage. The picture shows what I ended up with. Now using about 3-4 times more servo movement which is still not a lot (about 45 degrees) but much much better than the previous setup.

I am am using these pushrods from secraft that I picked up from the big aerobat specialist hobby shop (DA Australia actually) and are turnbuckle styled so you can do some very minor adjustments of them, and the look just like full sized pushrods! i also used them on the ailerons and had to replace the aileron servo arms because instead of drilling and tapping the arm for the 4-40 bolts, ole mate just drilled them out oversized. Slop central!

thanks

dave