Extreme Props
Hey Fast Prop People,
What's the most extreme prop situation that anyone out there has come across? As there have been some mention of planes in the ~200 mph range, it seems that those props must really be something special. As a curious guy who's always looking for the next RC project, I got to thinking about what this high speed really means.
I was looking at two specific situations with:
1) a 5 x 6 prop turning at 35.2 kRPM producing 1.81 lb of thrust at 200 mph and
2) a 5.5 x 6.5 prop turning at 33.0 kRPM producing 2.37 lb of thrust at 203 mph.
I came up with those numbers from propeller theory from one of my engineering courses but I don't think those equations were meant for such small props turning at such high RPM. Has anyone out there spun a prop this fast?
I've looked at props from Graupner, APC, and AeroNaut but haven't found either of these two. There doens't seem to be a very broad selection in the 5 - 6 in prop range. I'm also not sure what the max manufacturer RPM rating is for those props.
Has anyone clipped a high-speed prop? I suppose that I could cut down the Graupner 6.5 x 6.5 to 5.5 x 6.5 and do some precision balancing afterwards. This may cost some efficiency though...
So, for those who don't read long posts:
- Are there any 5.5 x 6.5 props out there that can take 33,000 RPM?
- Where can I get one?
-- Thanks, Ian