ORIGINAL: acdii
ORIGINAL: Gray Beard
One of the kit built Dirty Birdy's from a Blue Jay kit. The design is an original Bridi and it is a old school build. No glass fuse, it's all built up. I did try to install a .91 four stroke but there was no room on the fire wall but I was able to manage to get an SK .90 two stroke in it. Low RPM and High Torque. It flew even better then my old Kaos. Due to the mid air the second time out I never got to see it's full potential but I could hold knife edge from end to end of our flying site. I was very impressed with this one. It landed so slow and stable it was easier then a trainer. I have so many planes in line for my building board right now otherwise I would be building another one. If I do build another one I will be using my spring air retracts though. Just for that clean look. I think anyone with enough trainer time could fly this plane. I haven't flown the ARF yet so can't say about how that one is?
I have been eyeing that kit for a while now. How would it fly with a magnum 52 on it? You say the 91 didn't fit, thats the other motor I have.
A .52 four stroke? Not well at all. The planes are old Class C pattern planes and designed for two stroke 61s on a pipe. Knowing ahead of time the fire wall is too small for a 91 it's easy to out think. You just make a bigger fire wall. You can recess it a bit or add a little length to the cowl area. The beauty of kit building over ARFs are the mods you can do during the build. With a nice 91 FS or like I did with a Low RPM high torque engine you can do nice, slow verticle moves like big slow loops or stall turns. During the 60s and 70s you needed to be going fast to do this. The engines you can use now makes flying them much easier, you don't need to go fast any longer. At one point I had a YS 110 in my Kaos but that was just silly. When I went down to the OS 91FS I left that engine in it for years, a perfect match for how I liked to fly. Slow and smooth but able to jink around at will.
Making changes to a kit is easy if you know things in advance, pattern planes are no different then any others. I have a number of tricks to building any planes that used round engines too. They all have a few quirks of there own.