ORIGINAL: r-c-guy
However, in the meantime, I am waiting on the arrival of a BVM 96 from Dave Shadel of Perf Specialties which will be setup for trials on the Mustang...... It will be interesting..... They claim 26-27 k on 15% and a 10-10 or 10-11.
Well, there certainly is way too much BVM .96 HP advertised. To run a 10x10 at 27000 you need about real 14 HP!
So let’s go into detail: I own both the BVM 91 and 96 engines. These static rpm were achieved using the .96 and a MACS 1190 pipe:
7.5 x 12 custom made carbon fibre speed prop => 23200 rpm
8.0 x 12 custom made carbon fibre speed prop => 21900 rpm
9.0 x 10 carbon fibre APC 10x10 copy => 20200 rpm
These are real measurements, no claims. [sm=wink_smile.gif]
In each case there’s plenty potential for unloading, especially using that much of pitch.
But let us keep in mind a safe peak rpm of about
25000 for the .96 (more seems to be improbable) and about
real 7 HP of maximum output (even an unloading BVM 96 will not make more power).
Generally: Using props exceeding 9“ of diameter sadly will absorb too much peak rpm over 22000. We have to reduce prop diameter here to take advantage of the entire rpm peak of such an engine.
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