Originally Posted by
vertical grimmace
I wonder how a little ASP .12 would do on the Akromaster? I do have a BB Fox .15 I could use, or maybe the older Magnum .15, but it sounds like if you wanna keep this plane light, you need a light engine as well.
Hi Vert, If the ASP .12 is under 3.75ozs , it should keep the wing loading at an acceptable
level. The point of all my blabbing is that wing loading is the key factor for changing
directions; in essence; the ability for the model to "pop" a tight corner. Airfoil thickness
is not the most important factor. I'll just let that point sink in for now.
As for the Fox .15BB being suitable, it is not. The engine is way too heavy and way too
thirsty, and all the power that engine delivers is wasted on the Akromaster's small
wing area(240 sq"). Before the rule change that restricted venturi intake area;
many USA FAI Combat flyers were using modified Fox .15BB with lotsa Nitromethane
to be competitive with very high performance European(and Nelsons). Tom Fluker
a Texan, used modified Foxes to win the FAI World Combat championship in the late
1980s.
My Fai Combat models were powered by the Fox .15BB, they had 400 sq" wings, and
were capable of 89-93 mph, depending on nitro %. Stock Fox 15BBs would fly the
same model design 81-82 mph. So...Lighter engine, a displacement providing adequate
power loading; yields a model with a lighter wing loading, easier to meet the proper CG
without adding much tail ballast and if a smaller displacement engine is used, then the fuel
tank capacity is also smaller. I had to shorten the nose of my scratch built Akromaster
because of the smaller fuel tank. Going back to your Fox .15BB, you might have a great
flying model if you mount it in a 390 sq" FliteStreak! Top Flite actually showed a suggested
engine range of .15 cu" - .35 cu" engines in their early magazine advertising. If you think it
cannot possibly work; a no longer with us friend, built and flew a 'Streak with an MVVS
.12 cu" plain bearing diesel.
Tony