ORIGINAL: RVman
ORIGINAL: opjose
ORIGINAL: j.duncker
Training schools often use Graupner grey series props.
The Graupner props are the only ones that I've ever seen that had a warning about keeping the prop hydrated.
The warning states something along the lines of, if the prop is left in a too dry environment the plastic will dry out and become brittle over time. They advise re-hydrating the props.
This threw me for a loop! I had never heard of anything like this and I'm still wondering about it.
I see no other manufacturer include anything like this in their documentation or warnings.
Any idea as to what this is all about?
I had one (15-8 3 blade) that threw a blade in flight and caused the plane to crash. Maybe there is something in that warning?
I did not know that Graupner still included that warning.
Yes, boiling them will reduce the chance of breakage. In the days when I flew U control diesel combat with Tornado 8x6 [ Bright yellow anybody else remember them?] if you got old stock that had been sitting in the shop for months this was essential if they were to survive a crash.