Well here is another post in the continuing effort to "quantify" what our engines are doing.
I think the data is pretty good, however my interpretation of what a "Stunt Motor" is gets fuzzier with each new engine I test.
So this is a setup I must have been running some years back--an "original" TopFlite Nobler Arf with a Brodak 40. This was put together within the first month (or even faster) of when this first, of the modern era of Arf's, became available. I actually wrote a review of this plane and engine and posted it on SSW many years ago. Unfortunately the post was lost in one of the crashes SSW suffered back in that era. I don't even recall how long ago that was! Fortunately someone picked up the review and put it in Stunt News. I remember how surprised I was when I was reading SN and thinking how familiar the review was. When I saw my name at the end was when I realized it was my post!
That's the lead in for this data. After my difficulty with the side-mounted Fox35, I thought (haa!) that the B40 might provide a better example of a 4-2-4 engine, simply because it was mounted in a full fuse plane, and because it was always a good runner. And actually this was a pretty easy subject to resurrect from my "Boneyard"--up in the attic. Although the thought crossed my mind whether the hot-melt glue of this Chinese ARF was still up to the job after a number of summers in the attic (just as I
was getting ready to pull out of the wingover!!).
So the actual numbers---this is also an early Brodak 40, that I am running with a Tongue muffler to keep the weight down. All up weight is a little shy of 40oz (no fuel). I am running a un-obtanium Black Tornado Magnum 11-4 prop. Fuel tank is a 4 oz round clunk tank. Fuel is some %Nitro Sig 50-50 castor/synthetic fuel. I am not sure of the % because the label has fallen off the old fuel bottle. I am guessing it is 10% or so.
What follows is a selection of maneuvers. The technique to get the rpm is described here.
http://stunthanger.com/smf/index.php?topic=14196.0The B40 was pretty clean in terms of the sound--especially with the tongue muffler. Wow that sounded loud--I guess I am really use to electric power these days. Only issue was that a full scale plane flew overhead during the inside loops and interfered with the data. As a result, I reflew the inside loops at the end after the clover.
Also I note that the wind was almost non-existent.