Thread: Discussion 200mph with 70mm
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Old Oct 31, 2012, 10:59 AM
Jwmflying14 is online now
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United States, CA, Lompoc
Joined Nov 2010
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Sorry Rocket boy, weight has little to do with speed. We need to look at aerodynamics, followed by power. At 200 mph it doesn't matter much about weight, it will pretty much fly wings or not. Its landing and taking off where you run into problems with weight....

Mudrnunoc;
I agree the most aerodynamic airfoil is generally symetrical, as the by product of lift is drag. You should check out Laminar flow airfoils such as the NLF0414 used in full scale. very interesting stuff...

I simply was suggest the MH30 or 43 because this would probably be the EASIEST to shave the Zephyr wing down to if that makes sense....If you glass it (or carbon fiber), reinforce the wing, do some minor airfoil/wing reshaping and cut out the foam in the fuselage/pod area after glassing, you should have plenty of room for power, and the aerodynamics to push it. Heck you could even redo the entir forward fuselage to be cleaner. The added weight of the composite covered tail will even help with balancing when you have heavy power system up front!

I agree with the CS90 Idea, it will definitely be more pitch. Downfall, thicker root on the blades, thicker blades, heavier rotor, and it still might not be strong enough... But only testing could tell.

Keep in mind with 3kw in a 70mm EDF and the goal of speed an exhaust of about 70-73% FSA will be faster then the common 80%. We aren't concerned with thrut, but more so Efflux speed, and volume. At 200 mph venturing into reduce inlet area can help as well. Essentially reducing inlet area down to 90% or so allows for a lower pressure zone inside the inlet, it also allows a slightly higher RPM in the Fan itself. The vaccum created will be more than enough and it shouldn't starve the fan at all.

Once again, these are just my (slightly) educated opinions.
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