Gryphon
Posts: 1918
Joined: 7/11/2003
From: Charlotte,
NC, USA
Status: online
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chippedprop,
I believe you will agree that paying attention is the most important thing and will help being safe a lot more than any assisted launch device.
I launch 37-45 o.z. 1100W-1800W Stryker while at full throttle by myself. The key is paying attention.
Just before each single launch I go through the steps in my mind. I do not rush.
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One mistake that I've seen on various forums is seeing too small a prop. That will seriously hurt acceleration and launch capabilities.
Often you can listen to a guy's video and hear that the poor prop is not fully biting into the air and the watts are being wasted.
Given any number of cells, the prop size should be big enough to draw at least mid level amps.
Keeping the amps to a minimum could be a mistake, and that is even a bigger mistake as the volts go up given any particular motor.
Given any particular motor as the volts go up, the prop size goes down to maintain same amps, but then at some point the prop size is too small given the speed/drag/thrust combination. At those times increase in diameter will help the situation.
If such a situation arises with 5X5, a person should try 5.25X4.75, or even 5.5X4.5. Increased static amps will drop some at high speed when the pitch is less than diameter.
For 4.7X4.7, I would look for a prop in the 5X4.5 size (not sure who might make that size), or take the 5.5X4.5 and cut it down some.
With the bigger diameter props, the plane will have better flying characteristics, easier launch and better climbing and acceleration.
Too high a KV, voltage, or RPM noise (wow factor) or pitch speed is not always the key. With a perfectly matched setup a plane will fly much better and will be much more enjoyable.
Class is in session (for newbies):
Assuming a person wants to have a setup at 40A but prop size is too small. They can move away from 1:1 diameter to pitch ratio prop. They can choose a prop that has lower pitch number than diameter. They can prop for 42-45A static, but knowing that in flight they will drop to 40A. This way during launch or hard climbing, they will have little more power and a better prop that can also bite more/better into air, and then during the rest of the flight they can be down to 40A range (level wide open throttle at high speed).
Don't get me wrong there is nothing wrong with 1:1 props when they are of sufficient diameter size for an airframe and speed range. But copying mistakes of other rookies does not make it a good combination.
The above post is assuming sufficient breathing room left as far as MOTOR/ESC and battery goes.
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I look forward to seeing you at the Joe Nall fly in.
Is it a B-Y-O-B? 
Gryphon
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RE: FUNJET - 
