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Need some help from the airplane guys....


Old 06-27-2005, 12:48 PM
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Default Need some help from the airplane guys....

So I downloaded motocalc to do some calculations on prop and gearing.

Can someone either explain in simple terms, or direct me to a site that does, the details of propulsion dynamics in regards to flight?

How many ounces of thrust compared to model weight is good for basic flight, aerobatics, or 3D flight?

How does prop speed translate into forward airspeed of the plane?

In electric flight, how many watts per pound is acceptable? Recommended?

Bigger prop with lesser pitch has the same thrust as a smaller prop with higher pitch. Whats the benifits or downside to each?


I am trying to find a prop, power, gearing combination that will provide plenty of climbing power, vertical performance and a moderate top speed.

Basically, looking for torque rather than horsepower.


Also for the electric guys, I have some 3SLipo packs that are 12C, but what amp ratings can a nimh 2/3AA pack handle?

Does Mah rating have anything to do with discharge capability, or just runtime?
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Old 06-27-2005, 08:46 PM
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Default RE: Need some help from the airplane guys....

I can't tell you the details of propulsion dynamics, but I can lead you to the "Inflight" button after "Compute Report" and then hit the "Opinion" button. This will tell you if your over or under propped, etc, etc...

Mah does have to do with discharge capability. 12C means 12 times your mah is the max amps your battery can handle, for example if your battery is 1500mah, then 12 times 1500=18000mah or 18 amps. If the prop you choose draws more then 18 amps then your battery won't be able to keep up. I know NiMh's can handle a high amp draw, I would guess you would have to find out on the manufacturers listing what kind of draw it can take. If you search for setups of the particular plane your flying, you'll see a pattern of what everyone is using, and their experiences with it. Good luck.
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