David,
Thanks for the reply/description. Having been an aeronautical engineer for 30
years l appreciate both the theoretical and practical analysis of a problem.
Clearly you have a heap more experience in the practical sense, especially
w.r.t.
Europa flying.
I have at hand a bunch of tools (including Fluid-Dynamic Lift and Drag by
Hoerner/Borst,
CFD programs, etc) from which l would happily spend hours/days/weeks
quantifying this discussion. But that will have to wait until l finish this
pesky A380 work on my desk right now.
A rough calc (@50kt landing to standstill), along the lines of your suggestion,
reveals a flat plate drag load of about 96 lbf for the fine (zero degrees in
fact) pitched prop prop (4lbf for the feathered prop). This will reduce quickly
with the square of the speed (@25 kts max load is approx 24 lbf). The
proportion
of total drag during the ground run will depend on a heap of stuff (tyre
pressures, ground friction), etc.
So unbraked l think you have a point. With normal (or higher) braking l think
the difference will be a lot less (as prop drag
--------
John Wighton
Europa XS trigear G-IPOD
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