Hi there all,
I'm very impressed by the level of expertise available in this community,
many thanks to each and everyone. To put my stone on the edifice, I will add
that using a C/S prop (Airmaster on 912) give an additional comfort of
flight within perturbed windy weather, as the prop variation acts as a shock
absorber. Together with the very good profile of the wing make my flight
smooth, much better than some other comparable birds like Dynamics or
Lionceaux.
Max Cointe
F-PMLH TriGear Kit #560
912ULS Airmaster 400 hours
-----Message d'origine-----
De: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] De la part de John Wighton
Envoy: mercredi 11 janvier 2012 13:32
: europa-list@matronics.com
Objet: Europa-List: Re: VP prop, good idea? which one?
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
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=363034#363034
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